JP2011137083A - Metallic pigment and ultraviolet-curable composition obtained by compounding the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metallic pigment inhibiting the occurrence of gelation even when being compounded with an ultraviolet-curable composition such as a UV metallic coating composition or a UV metallic ink composition, and not accompanying the risk of ignition, explosion or the like. <P>SOLUTION: The metallic pigment to be compounded in the ultraviolet-curable composition includes metal particles and a first film covering the surfaces thereof, wherein the first film comprises amorphous silica. Preferably, the surface of the first film is treated with a silane coupling agent. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a metal pigment capable of improving stability with time and obtaining a good metallic feeling when blended in an ultraviolet curable composition, and an ultraviolet curable composition blended with the metal pigment.

  In recent years, metallic paints and metallic inks containing metal pigments have been used in many fields such as automobile exteriors, electrical equipment, buildings, stationery, office equipment, communication equipment, cosmetics, etc. due to their unique and excellent design. Has been used in.

  A coating film formed using a metallic paint reflects the incident light from the outside with a scaly metallic pigment (that is, a metal pigment) contained in the coating film, and exhibits a sparkling design. The reflection of light, combined with each color tone of the coating film, exhibits a unique appearance excellent in design. These effects are the same also in the printed matter formed using metallic ink.

  Aluminum is excellent in metallic luster, inexpensive and easy to handle because of its low specific gravity. For this reason, metallic pigments composed mainly of metal particles, typically aluminum flakes, are used in metallic designs in general automotive paint finishes, plastic paint finishes, printing inks, resin moldings, and the like.

  On the other hand, in the paint field, a large amount of carbon dioxide is emitted due to scattering of VOC (volatile organic compounds) during painting and energy consumption during drying of the paint. These are generally well known as photochemical oxidant causative substances and substances that cause global warming, and countermeasures are urgently needed. Among them, the use of so-called UV paints and UV inks using an ultraviolet curable resin that is advantageous in terms of high-speed curability, low pollution, and energy saving without using an organic solvent is increasingly used. Therefore, the demand for metal pigments including aluminum flakes that can be suitably blended in UV paints and UV inks is also increasing.

  The UV paints and UV inks containing the metal pigments are known as UV metallic paints and UV metallic inks, respectively. In order to meet the growing demand for such UV metallic paints and UV metallic inks, When an aluminum pigment is used as a metal pigment used in paints or UV metallic inks, an aluminum pigment in which the surface of the aluminum flake is coated with a higher saturated or unsaturated fatty acid such as stearic acid or oleic acid and its derivatives has been used. It was.

  However, such an aluminum pigment has a problem in that it has poor storage stability when it is blended in a UV metallic paint or a UV metallic ink, and causes gelation. In other words, in UV metallic paints and UV metallic inks containing aluminum pigments, the monomer and oligomer components in UV metallic paints and UV metallic inks are activated by aluminum ions on the surface of aluminum pigments during storage, and radical polymerization is promoted. Therefore, problems such as the gelation or solidification of the paint or ink in the container have occurred. Such a problem has also occurred in metal pigments other than aluminum pigments. For this reason, in the field of UV metallic paints and UV metallic inks, generally, metal pigments such as aluminum pigments are hardly used.

  In order to solve this gelation problem, Patent Document 1 (WO 2005/090487 pamphlet) is suitable for UV metallic inks or UV metallic paints containing metal flakes and nitrocellulose as essential components. Metallic pigment compositions have been proposed. Although the gelation can be suppressed to some extent by the proposal, further improvement in stability over time is required. In addition, the nitrocellulose used according to the proposal easily ignites and explodes, and is dangerous in the production of the metallic pigment composition. Therefore, its use is restricted from the viewpoint of safety.

  On the other hand, the nitrocellulose in the above proposal is considered to prevent gelation by coating the surface of the metal flakes. As materials for coating the surface of metal pigments including aluminum pigments, for example, various resins , Coupling agents, phosphoric acid compounds, molybdenum compounds, chromic acid compounds, silica (Patent Documents 2 and 3), and combinations thereof are known.

International Publication No. 2005/090487 Pamphlet JP 2003-147226 A International Publication No. 2004/096921 Pamphlet

  In order to solve the gelation problem that occurs when a metallic pigment is blended with a UV metallic paint or UV metallic ink, it is conceivable to coat the surface of the metallic pigment with another substance. As materials for coating the surface of the metal pigment, for example, various resins, coupling agents, phosphoric acid compounds, molybdenum compounds, chromic acid compounds, silica, and combinations thereof are known as described above.

  Among these substances, various resins are expected to generate gelation similar to the above, as the unreacted monomer component contained therein reacts with the monomer component or oligomer component in the UV metallic paint or UV metallic ink. Is done. In addition, coupling agents, phosphoric acid compounds, molybdenum compounds, and chromic acid compounds cannot sufficiently cover the surface of the metal pigment with a continuous film, and therefore, the influence of metal ions existing on the surface of the metal pigment is affected. It is considered that the occurrence of gelation cannot be sufficiently prevented since it cannot be sufficiently suppressed.

  On the other hand, since the coating of a metal pigment with silica is originally intended to improve the stability of the metal pigment in an aqueous medium, the metal pigment coated with silica is excellent in dispersibility in an aqueous medium, but UV It was considered difficult to disperse in oily media such as metallic paints or UV metallic inks. Moreover, since silica has a high affinity with water and the surface is thought to be hydrated, the effect of moisture and the residual hydrolysis catalyst used during the synthesis of silica hinders the curing of UV curable resins. It is also expected.

  Therefore, it is impossible to prevent the above gelation from occurring while satisfying the normal use conditions of the UV metallic paint or UV metallic ink by coating the metal pigment with these materials, particularly silica. It was thought to be.

  The present invention has been made under such circumstances, and even when blended with an ultraviolet curable composition such as a UV metallic coating composition or a UV metallic ink composition, the occurrence of gelation can be suppressed. An object of the present invention is to provide a metal pigment that can be produced and does not involve dangers such as ignition and explosion.

  The present inventor has conducted extensive studies to solve the above-mentioned problems, and has obtained a surprising finding that a favorable result can be obtained with a metal pigment coated with silica contrary to the conventional expectation. As a result of repeated studies, the present invention has finally been completed.

  That is, the metal pigment of the present invention is a metal pigment for blending into an ultraviolet curable composition, and includes metal particles and a first film that covers the surface of the metal pigment. It is characterized by comprising crystalline silica.

  Here, the surface of the first coating is preferably treated with a silane coupling agent. Moreover, it is preferable that the said metal pigment contains 0.01-100 mass parts of silicon with respect to 100 mass parts of metal particles.

  Moreover, this invention relates also to the ultraviolet curable composition which mix | blended said metal pigment, It is preferable that this ultraviolet curable composition is a UV metallic coating composition or a UV metallic ink composition.

  The metal pigment of the present invention can suppress the occurrence of gelation even when blended with an ultraviolet curable composition such as a UV metallic paint composition or a UV metallic ink composition, and has a risk of ignition and explosion. It has an excellent effect of not being accompanied.

The present invention is described in further detail below.
<Ultraviolet curable composition>
The ultraviolet curable composition in the present invention is a composition that is cured by ultraviolet rays to produce a resinous product (that is, a film or a molded product). Specifically, a conventionally known so-called UV monomer or UV oligomer is used. First, it is a composition containing a photopolymerization initiator and various additives.

  Specific examples of such an ultraviolet curable composition include a UV metallic coating composition and a UV metallic ink composition.

<Metal pigment>
The metal pigment of the present invention is for blending in the ultraviolet curable composition as described above, and includes metal particles and a first film that covers the surface of the metal particle. It is characterized by comprising amorphous silica.

  Since the metal pigment of the present invention has this first coating, when this is blended with the UV curable composition, the UV monomer or UV oligomer in the UV curable composition is in direct contact with the surface of the metal pigment. Therefore, the monomers and oligomers are not activated during storage of the ultraviolet curable composition, and radical polymerization is not promoted, so that the ultraviolet curable composition during storage gels or solidifies. There is no problem.

  In addition, when the surface of the first coating is further treated with a silane coupling agent, the metal pigment of the present invention contains components other than the metal pigment contained in the ultraviolet curable composition (particularly a resin cured by ultraviolet rays) and the metal. The effect of improving the adhesion with the pigment is obtained.

  Such a metal pigment of the present invention is usually blended in an ultraviolet curable composition in an amount of 0.1 to 50% by mass, preferably 1 to 30% by mass, and more preferably 3 to 20% by mass.

<Metal particles>
Examples of the metal particles constituting the metal pigment of the present invention include aluminum, zinc, copper, silver, nickel, titanium, stainless steel, or metal particles made of an alloy containing at least one of these metals. Among these metal particles, aluminum particles, copper particles, and alloy particles of copper and zinc are particularly suitable because they are excellent in metallic luster and are inexpensive and relatively easy to handle.

  The shape of such metal particles is not particularly limited and may take various shapes such as granular, plate-like, massive, and flake-like (scale-like), but gives excellent metallic feeling and brightness to the coating film and printed matter. For this purpose, a flake shape is preferred.

  The average particle size of the metal particles is preferably in the range of 0.1 to 100 μm, and more preferably in the range of 0.5 to 60 μm. When the average particle diameter of the metal particles is 0.1 μm or more, the metallic feeling or the glitter feeling is good. In addition, when the average particle size of the metal particles is 100 μm or less, the metal particles can be prevented from sticking out to the surface of the coating film or the ink film, and there is little risk that the smoothness or sharpness of the surface is lowered. This is also advantageous in terms of cost. The average particle diameter of such metal particles can be obtained by calculating the volume average from the particle size distribution measured by the laser diffraction method.

  When flaky metal particles are used, the average thickness of the metal particles is preferably in the range of 0.001 to 5 μm, and more preferably in the range of 0.005 to 2 μm. When the average thickness of the metal particles is 0.001 μm or more, since the metal particles have sufficient strength, the workability during the manufacturing process is good. When the average thickness of the metal flakes is 5 μm or less, there is little risk that the smoothness or sharpness of the coating film or ink film is lowered, and it is advantageous in terms of production cost.

The thickness is obtained by the following calculation.
Average thickness (μm) = 10000 / 2.7 (g / cm ³ ) × WCA (cm ² / g)
(Average thickness (μm) = 4000 / WCA (cm ² / g) can also be simply expressed)
WCA in the above formula represents a water surface diffusion area (cm ² / g), which can be measured according to JIS K5906.

  In order to produce flakes as metal particles, a metal powder as a raw material and a grinding aid are usually used in an organic solvent using a grinding device having grinding media such as a ball mill or an attritor. Are pulverized and the metal powder is flaked to produce flaky metal particles. The grinding aid suppresses unnecessary oxidation of the metal flake surface and has an effect of improving gloss. The grinding aid is not particularly limited, and conventionally known ones can be used. For example, fatty acids such as oleic acid and stearic acid, fatty acid amines, fatty acid amides, aliphatic alcohols, ester compounds and the like are preferable. Can be used.

  The organic solvent used at the time of grinding with the metal powder and the grinding aid is not particularly limited, and conventionally known ones can be used. For example, hydrocarbon solvents such as mineral spirits, solvent naphtha, alcohols, etc. , Ether solvents and ester solvents can be used. In general, a hydrocarbon solvent with a high boiling point is suitably used in consideration of safety problems such as the flash point of the solvent during grinding. After grinding, the material to be ground passes through a screen to remove coarse powder, and then the organic solvent and metal particles are separated into solid and liquid using a filter press or the like, whereby flakes having a metal content of about 50 to 80% by mass are obtained. A paste of metal-like metal particles is obtained. The content of the organic solvent in the paste is preferably as small as possible from the viewpoint of ensuring high-speed curability of the coating film or ink film.

<First coating>
The first film of the present invention is made of amorphous silica. The first coating covers the surface of the metal particles, but may be formed so as to be in direct contact with the surface of the metal particles, or may be formed via an underlayer described later. In the present invention, even when the first film is formed through the underlayer (that is, on the underlayer) as described above, it is expressed as “cover the surface of the metal particles”.

Here, the amorphous silica means amorphous silica having no crystal structure, specifically, siloxane (H ₃ SiO (H ₂ SiO) _m SiH ₃ ), silica hydrate (SiO ₂ .mH). ₂ O), silica hydroxide (SiO _n (OH) _4-2n ) and the like. In the above formula, m represents an arbitrary positive integer, and n represents a number in the range of 0 ≦ n ≦ 2.

  Amorphous silica has a very dense layer structure and is very stable with respect to UV monomers and UV oligomers contained in the ultraviolet curable composition. Further, the metal particles are formed from the amorphous silica. The metal pigment of the present invention is very stable in the ultraviolet curable composition because it is completely covered with the first coating.

  Further, the first film of the present invention does not need to be a film made of only amorphous silica, and may contain other additives and impurities as long as the effects of the present invention are not impaired. That is, in the present invention, “consisting of amorphous silica” includes not only the case of consisting of amorphous silica but also the case of including other components in this way.

  As a method of forming such a first film of the present invention, by adjusting the pH of a dispersion solution containing metal particles, an organic silicon compound, and a hydrolysis catalyst having or not having a base layer described later, A method of hydrolyzing the organosilicon compound to deposit the first coating on the surface of the metal particles or the surface of the underlayer can be exemplified, but is not limited thereto, and any known method A method may be used. When employing the method exemplified above, it is preferable to uniformly disperse or dissolve each component by stirring the dispersion solution at an appropriate speed.

  In the above method, it is preferable to adjust the pH value of the dispersion solution by adding a hydrolysis catalyst for simplification of the production process, but the method of adjusting the pH value of the dispersion solution is as described above. The method is not limited only to the method of adding a hydrolysis catalyst to the solution, and the pH of the dispersion solution may be adjusted using other acidic compounds and / or alkaline compounds.

  Here, in this specification, the “organosilicon compound” is a concept including both an organosilicon compound and a condensate of an organosilicon compound.

  The organosilicon compound used in the present invention is not particularly limited, and by adjusting the pH of a dispersion solution containing metal particles having or not having an underlayer, the organosilicon compound, and a hydrolysis catalyst, A known organosilicon compound and its condensate that can hydrolyze the organosilicon compound to form the first film on the surface of the metal particles or the surface of the underlayer can be mentioned.

  Specific examples of such an organosilicon compound include tetraethoxysilane, tetramethoxysilane, tetraisopropoxysilane, and their condensates. These organosilicon compounds may be used alone or in combination of two or more.

  The hydrolysis catalyst used in the present invention is not particularly limited, and by adjusting the pH of a dispersion solution containing metal particles with or without a base layer, an organosilicon compound, and the hydrolysis catalyst, the hydrolysis catalyst is used. A known hydrolysis catalyst that hydrolyzes the organosilicon compound by the action of the decomposition catalyst and forms the first film on the surface of the metal particles or the surface of the underlayer can be used.

  Specific examples of such hydrolysis catalyst include monoethanolamine, diethanolamine, triethanolamine, ammonia, ethylenediamine, t-butylamine, 3-aminopropyltriethoxysilane, n-2-aminoethyl-3-aminopropyltrimethyl. Basic hydrolysis catalysts such as ethoxysilane, n-2-aminoethyl-3-aminopropylmethyldimethoxysilane, urea, sodium silicate, sodium hydroxide, and acids such as oxalic acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, phosphonic acid Examples include hydrolysis catalysts.

  Here, from the viewpoint of the reaction rate in the hydrolysis step, it is preferable to use a basic hydrolysis catalyst rather than an acidic hydrolysis catalyst. Among the basic hydrolysis catalysts, triethanolamine, ammonia, ethylenediamine, 3-aminopropyltriethoxysilane, and the like are particularly preferable from the standpoint of quality.

  Moreover, it is preferable to use a hydrophilic solvent as the solvent of the dispersion solution containing the metal particles with or without the base layer, the organosilicon compound, and the hydrolysis catalyst. Specific examples include 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, acetone, or the like can be used, but in particular, when aluminum particles are used as the metal particles, it is preferable in that an abnormal reaction between the aluminum particles and water is avoided.

  However, water may be contained in these hydrophilic solvents. When aluminum particles are used as the metal particles, the content of water in the hydrophilic solvent is particularly preferably 20% by mass or less from the viewpoint of avoiding an abnormal reaction between the aluminum particles and water.

  Further, in the dispersion solution containing the metal particles with or without the underlayer, the organosilicon compound, and the hydrolysis catalyst, 100 parts by mass of the metal particles (in the present invention, only the metal particles are included even when the underlayer is provided). The content of the organosilicon compound is preferably 2 parts by mass or more, and more preferably 5 parts by mass or more. Moreover, it is preferable that content of this organosilicon compound is 200 mass parts or less, and it is more preferable if it is 100 mass parts or less.

  When the content of the organosilicon compound is less than 2 parts by mass, the first coating tends to be insufficiently formed to cover the surface of the metal particles, and the content of the organosilicon compound exceeds 200 parts by mass. Then, there is a tendency that the aggregation of the metal particles and the reduction of the glitter feeling become remarkable. In addition, when adding an organosilicon compound, you may add gradually and may add at once.

  In addition, in the dispersion solution containing the metal particles with or without the base layer, the organosilicon compound, and the hydrolysis catalyst, the content of the hydrolysis catalyst is 0.1 parts by mass or more with respect to 100 parts by mass of the metal particles. It is preferable that it is 0.5 mass part or more. The content of the hydrolysis catalyst is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less.

  When the content of the hydrolysis catalyst is less than 0.1 parts by mass, the amount of precipitation of the amorphous silica constituting the first film tends to be insufficient, and the content of the hydrolysis catalyst is 20 masses. When it exceeds the part, the aggregation of the metal particles tends to be remarkable.

  Further, in the dispersion solution containing the metal particles with or without the underlayer, the organosilicon compound, and the hydrolysis catalyst, the content of the hydrophilic solvent is 500 parts by mass or more with respect to 100 parts by mass of the metal particles. It is more preferable that it is 1000 parts by mass or more. Further, the content of the hydrophilic solvent is preferably 10,000 parts by mass or less, and more preferably 5000 parts by mass or less.

  When the content of the hydrophilic solvent is less than 500 parts by mass, the viscosity of the slurry tends to be high and stirring tends to be difficult. When the content of the hydrophilic solvent exceeds 10,000 parts by mass, the treatment liquid is recovered, Regeneration costs tend to increase.

  Further, in the step of forming the first film on the surface of the metal particles having or not having the underlayer, the temperature of the dispersion solution in the step is preferably 20 ° C. or higher, and 30 ° C. or higher. More preferably. Moreover, it is preferable that the temperature of the dispersion solution in this process is 90 degrees C or less, and it is more preferable if it is 80 degrees C or less.

  When the temperature of the dispersion solution during this step is less than 20 ° C, the formation rate of amorphous silica tends to be slow and the treatment time tends to be long, and the temperature of the dispersion solution during this step exceeds 90 ° C. The risk of reaction runaway tends to increase.

  In the step of forming the first film on the surface of the metal particles with or without the underlayer, the reaction time is preferably 1 hour or longer, more preferably 3 hours or longer. The reaction time is preferably 48 hours or shorter, more preferably 24 hours or shorter. When this reaction time is less than 1 hour, the formation of the first film tends to be insufficient, and when this reaction time exceeds 48 hours, the processing cost tends to increase.

  Here, in the step of forming the first film on the surface of the metal particles having or not having the base layer, the pH value of the dispersion solution changes during the reaction, and therefore it is necessary to adjust the pH value appropriately. is there. At that time, it is desirable to adjust the pH value by adding a hydrolysis catalyst, but it is dispersed using other acidic and / or alkaline compounds as long as the effects (characteristics) of the metal pigment of the present invention are not impaired. The pH of the solution may be adjusted.

  In the dispersion solution containing the metal particles with or without the underlayer, the organosilicon compound, and the hydrolysis catalyst, the pH is preferably 7 or more when the basic hydrolysis catalyst is used. .5 or more is more preferable. Further, the pH of this dispersion solution is preferably 11 or less, and more preferably 10 or less.

  If the pH of this dispersion is less than 7, the formation rate of amorphous silica tends to be low, and if the pH of the dispersion in this process exceeds 11, the aggregation of metal particles and the reduction of glitter Tend to be larger.

  In the step of forming the first film on the surface of the metal particles having or not having the base layer, it is more amorphous to use a basic hydrolysis catalyst than to use an acidic hydrolysis catalyst. This is preferable because the formation rate of silica is fast and the productivity is good.

  On the other hand, in the dispersion solution containing the metal particles with or without the base layer, the organosilicon compound, and the hydrolysis catalyst, the pH is preferably 1.5 or more when the acidic hydrolysis catalyst is used. Two or more are more preferable. The pH of the dispersion is preferably 4 or less, and more preferably 3 or less.

  If the pH of the dispersion is less than 1.5, the risk of runaway reaction tends to increase. If the pH of the dispersion in this process exceeds 4, the deposition rate of amorphous silica increases. There is a tendency to become smaller.

  The thickness of the first coating film of the present invention is preferably in the range of 1 to 500 nm. In the case of 1 nm or less, it becomes difficult to suppress the reaction to the UV monomer and UV oligomer in the ultraviolet curable composition, and the storage stability is lowered. On the other hand, when the thickness is 500 nm or more, the color tone of the coating film is lowered and the hiding power is lowered. A more preferable thickness of the first coating is 10 to 350 nm, and a more preferable thickness is 20 to 200 nm.

  The thickness of the first coating can be measured by observation with a TEM (transmission electron microscope), but when the thickness is 50 nm or less, it should be measured by XPS (X-ray photoelectron spectroscopy). Is preferred.

<Treatment with silane coupling agent>
In the metal pigment of the present invention, the surface of the first coating can be treated with a silane coupling agent. That is, the surface of the first coating of the present invention may be treated with a silane coupling agent. By treating the surface of the first film with the silane coupling agent in this manner, the reactivity with respect to the monomer and oligomer in the ultraviolet curable composition can be further suppressed, and adhesion (metal pigment and resin and Various effects can be expected, such as improvement of physical properties of the coating film such as adhesion of the resin and adhesion to the object to be coated, improvement of dispersibility in the ultraviolet curable composition, and improvement of the orientation of the metal particles.

  When the surface of the first coating is treated with a silane coupling agent, the surface of the first coating may be in a state where it is coated with a single coating made of a silane coupling agent. The ring agent reacts with the amorphous silica constituting the first coating or the organosilicon compound remaining in the first coating to form a composite coating of the first coating and the silane coupling agent. It may be in such a state.

  Such a treatment with a silane coupling agent is generally considered to be performed by hydrolyzing the silane coupling agent and reacting with a hydroxyl group in the amorphous silica constituting the first film.

  Examples of the silane coupling agent include methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, 3-aminopropyl-trimethoxysilane, n-methyl-3- Aminopropyl-trimethoxysilane, 3-aminopropyl-triethoxysilane, 3-aminopropyl-tris (2-methoxy-epoxy-silane), n-aminoethyl-3-aminopropyltrimethoxysilane, n-aminoethyl- 3-aminopropyl-methyl-dimethoxysilane, 3-methacryloxypropyl-trimethoxysilane, 3-methacryloxypropyl-methyl-dimethoxysilane, 3-acryloxypropyl-trimethoxysilane, 3- Lysidyloxypropyl-trimethoxysilane, 3-glycidyloxypropyl-methyl-dimethoxysilane, 3-mercaptopropyl-trimethoxysilane, 3-mercaptopropyl-triethoxysilane, 3-mercaptopropyl-methyldimethoxysilane, vinyltrichlorosilane , Vinyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris (2-methoxyethoxy) silane, vinyltriacetoxysilane, 3- (3,4-epoxycyclohexylethyltrimethoxy) silane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-anilidepropyltrimethoxysilane 3- (4,5-dihydroimidazolepropyltriethoxy) silane, n-phenyl-3-aminopropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, trifluoropropyltrimethoxysilane 3-isocyanatopropyltriethoxysilane, p-styryltrimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, octadecyltriethoxysilane, phenyltrimethoxysilane, phenyltri Examples include ethoxysilane and diphenyldiethoxysilane.

Particularly preferable silane coupling agents include the following compounds.
R _A —Si (OR _B ) ₃ or R _A —SiR _B (OR _B ) ₂ or R _A —SiR _A (OR _B ) ₂
R _A : C 2-18 alkyl group, aryl group, or alkenyl group R _B : C 1-3 alkyl group Specifically, the following compounds are exemplified.

  For example, n-propyltrimethoxysilane, isobutyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, octadecyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane and the like can be mentioned.

  The method of treating the surface of the first coating of the present invention with a silane coupling agent is almost the same as the method of forming the first coating, and can be performed by hydrolyzing the silane coupling agent. And a silane coupling agent will react with the hydroxyl group in the amorphous silica normally contained in a 1st film.

  More specifically, the organosilicon compound and the silane coupling are adjusted by adjusting the pH of the dispersion solution containing the metal particles with or without the base layer, the organosilicon compound, the silane coupling agent, and the hydrolysis catalyst. The agent is hydrolyzed to form a first coating on metal particles with or without a base layer, and the surface is treated with a silane coupling agent.

  In this case, in order to perform stepwise the formation of the first film by hydrolysis of the organosilicon compound and the treatment by hydrolysis of the silane coupling agent, the silane cup is formed after the first film is once formed by hydrolysis. It is preferable to treat the surface of the first film with a silane coupling agent by adding a ring agent and further hydrolyzing it.

  In addition, various conditions, such as the reaction solvent for processing with a silane coupling agent, temperature, a hydrolysis catalyst, are the same as the conditions at the time of forming the said 1st film.

  The amount of the silane coupling agent is 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the metal particles. When the amount of the silane coupling agent is less than 0.1 parts by mass, the desired effect tends not to be obtained. When the amount exceeds 20 parts by mass, the amount of unreacted silane coupling agent increases and the physical properties of the coating film decrease. Tend to.

  After the base layer (only when formed) and the first film are formed on the metal particles, and after the treatment with the silane coupling agent is completed, the dispersion solution is prepared using the above hydrophilic solvent not containing water. After washing, it is preferable to remove water and unreacted substances from the cake containing the metal pigment of the present invention by filtration using a filter.

  Moreover, you may heat-process the cake containing the metal pigment of this invention at the temperature of the range of 100-500 degreeC after that as needed.

  In addition, the step of forming the base layer, the step of forming the first coating, and the step of treating with the silane coupling agent may be performed in different dispersion solutions on the surface of the metal particles, or It is also possible to carry out continuously after appropriately adjusting the components in the same dispersion solution.

<Silicon content>
The metal pigment of the present invention preferably contains silicon in the range of 0.01 to 100 parts by mass with respect to 100 parts by mass of the metal particles. Here, the silicon content (parts by mass) indicates the amount of silicon element contained in the first film (ie, contained in the amorphous silica), but the surface of the first film is silane. In the case of being treated with a coupling agent, the amount of silicon element contained in the silane coupling agent is also added. The silicon content is more preferably 0.1 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the metal particles.

  When the silicon content is less than 0.01 parts by mass, the stability of the metal pigment in the ultraviolet curable composition tends to decrease, and when the silicon content exceeds 100 parts by mass. In some cases, the metal pigment aggregates, the concealability is lowered, and the color tone such as metallic luster is impaired.

<Underlayer>
The metal pigment of the present invention can form a base layer on metal particles, and can form a first coating on the base layer. This underlayer has a function of accelerating the formation of the first film as a nucleus for the deposition of the first film when the first film is formed. Thereby, the thickness of the first coating becomes uniform, and the reaction with the UV monomer or UV oligomer contained in the ultraviolet curable composition can be more sufficiently suppressed.

  As an example of such an underlayer, a layer made of a single film or a mixture film composed of at least one of oxides, hydroxides, and hydrates containing molybdenum (hereinafter referred to as “a layer containing molybdenum”). Examples thereof include layers containing metal element oxides constituting metal particles, but are not limited thereto.

  A method for forming a layer containing molybdenum as a base layer on the surface of the metal particles is not particularly limited, but preferred methods include, for example, the following methods. That is, a metal particle and a solution containing a molybdenum compound as described below are mixed in a slurry state or a paste state and stirred or kneaded to form a hydrated film containing molybdenum on the surface of the metal particle, and then heated. The method of using an oxide film is mentioned. As a method for forming such a layer containing molybdenum, a conventionally known method disclosed in, for example, Japanese Patent Application Laid-Open No. 09-328629 can be employed.

Molybdenum compounds used for forming a layer containing molybdenum include a composition formula Mo _x O _y · mH ₂ O ₂ · nH ₂ O (where x is 1 or 2, y is an integer of 2 to 5, m and n are Examples thereof include polymolybdic acid peroxide, ammonium molybdate, phosphomolybdic acid and the like represented by any arbitrary positive number). For example, polymolybdic acid peroxide can be prepared by dissolving metal molybdenum powder, molybdenum oxide or the like in an aqueous hydrogen peroxide solution (concentration 5 to 40% by mass). These molybdenum compounds are 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 Dissolve in a hydrophilic solvent such as glycol monopropyl ether or acetone to obtain a treatment solution. The treatment solution may contain water.

  The amount of molybdenum in the layer containing molybdenum is preferably 0.01 to 3.0 parts by mass, more preferably 0.05 to 2.0 parts by mass with respect to 100 parts by mass of the metal particles. The amount of molybdenum is desirably changed according to the specific surface area of the metal particles to be treated. It is preferable that the amount of molybdenum is increased for metal particles having a large specific surface area and decreased for metal particles having a small specific surface area. When the amount of molybdenum is 0.01 parts by mass or more with respect to 100 parts by mass of the metal particles, the thickness uniformity of the first coating and the chemical stability of the metal particles when forming the first coating are good. Yes, when it is 3.0 parts by mass or less, for example, the color tone of metal particles such as metallic luster and the like are prevented from agglomerating and the coating film properties such as moisture resistance, adhesion and weather resistance are good. Maintained.

  On the other hand, a method for forming a layer containing an oxide of a metal element constituting a metal particle as a base layer on the surface of the metal particle is not particularly limited, but a preferable method is, for example, treating the surface of the metal particle with hydrogen peroxide The method of forming the said oxide can be mentioned. By treating the surface of the metal particle with hydrogen peroxide, the fatty acid adsorbed on the surface of the metal particle is removed, and the surface of the metal particle is oxidized to include an oxide of a metal element constituting the metal particle. A layer is formed. As a result, the surface of the metal particles is brought into a surface state in which the first film is easily grown starting from the layer.

  The above-described method will be described more specifically. By mixing metal particles and a solution containing hydrogen peroxide in a slurry state or a paste state and stirring or kneading, the metal particles constituting the metal particles are included on the surface of the metal particles. Examples thereof include a method of forming a hydrated film and then converting the hydrated film into an oxide film by heating. For example, when aluminum particles are used as metal particles and the aluminum particles and a solution containing hydrogen peroxide are mixed in a slurry state or a paste state and stirred or kneaded, a hydrated film containing aluminum is formed on the surface of the aluminum particles, By further heating this, an oxide film such as an aluminum oxide film or a boehmite film is formed.

  As the solution containing hydrogen peroxide in the above, a solution obtained by dissolving hydrogen peroxide in a solvent can be typically used. As the solvent, in addition to water, alcohol, glycol, glycol ether, ketone organic solvents and the like can be used, and a mixed solvent of water and organic solvent can also be used. The hydrogen peroxide concentration in the solution is preferably in the range of 0.0001 to 45% by mass.

<Applications>
The metal pigment of this invention is for mix | blending with an ultraviolet curable composition. The present invention relates not only to such a metal pigment but also to an ultraviolet curable composition containing the metal pigment. And it is preferable that the ultraviolet curable composition of this invention is a UV metallic coating composition or a UV metallic ink composition.

  When the metal pigment of the present invention is blended with an ultraviolet curable composition, the UV monomer or UV oligomer in the ultraviolet curable composition is not activated, and radical polymerization is not accelerated. There is no problem of gelation or solidification.

  In general, the components of the UV metallic coating composition and the UV metallic ink composition are mainly composed of a resin component, a photopolymerization initiator, and the like. Here, the UV metallic ink composition is mainly composed of a component that does not contain an organic solvent and solidifies 100% in principle. On the other hand, a UV metallic coating composition may use a 10 to 20% diluent to lower the viscosity due to leveling problems.

  In the UV metallic coating composition and the UV metallic ink composition, the metal pigment of the present invention is blended in the UV metallic coating composition and the UV metallic ink composition so as to be in the range of 0.1 to 50% by mass. Is preferred. When the compounding amount of the metal pigment is 0.1% by mass or more, a sufficient metallic effect is obtained, and when it is 50% by mass or less, the physical properties and weather resistance of the UV metallic coating composition and the UV metallic ink composition. There is little risk of adversely affecting performance, corrosion resistance, mechanical strength, etc.

  As the resin component of the UV metallic coating composition and the UV metallic ink composition, those that are cured by ultraviolet rays are generally used. Examples of the resin component that is cured by ultraviolet rays include those composed of reactive monomers (that is, UV monomers) and reactive oligomers (that is, UV oligomers). These monomers and oligomers are cured (polymerized) by ultraviolet rays to become resinous, but the UV metallic coating composition and the UV metallic ink composition may contain a polymer.

  Although it does not specifically limit as a reactive monomer, For example, the acrylate of 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl acryloyl phosphate, tetrahydrofurfuryl acrylate, a tetrahydrofurfuryl derivative, etc. Monofunctional monomer, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, dipentaerythritol hexaacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, Diethylene glycol diacrylate, neopentyl glycol diacrylate, hydroxybivalate ester neopentyl glycol dia Relate, bifunctional monomers such as tripropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, include trifunctional monomers such as dipentaerythritol hexaacrylate.

  Examples of the reactive oligomer include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate (for example, diglycerin polyglycidyl ether acrylate) and the like. In addition, the polymer is not particularly limited. For example, an acrylic resin, an alkyd resin, a polyester resin, a polyurethane resin, a polyvinyl acetate resin, a nitrocellulose resin, a fluororesin, and the like having an unsaturated double bond. Can be suitably used.

  In recent years, UV curable water-soluble resins and emulsion resins may be used as the resin component, but they may be contained. Moreover, as a diluent (solvent), if it is a small amount, you may contain a general organic solvent and water.

  Although it does not specifically limit as a diluent, For example, a phthalic acid compound, a monomer, etc. are illustrated. As phthalic acid compounds, phthalic acid monomethyl ester, phthalic acid monoethyl ester, phthalic acid monophenyl ester, phthalic acid monobenzyl ester, phthalic acid monocyclohexyl ester, phthalic acid dimethyl ester, phthalic acid diethyl ester, phthalic acid methyl ethyl ester Phthalic acid dibutyl ester, phthalic acid dioctyl ester, phthalic acid dihexadecyl ester, phthalic acid dicyclohexyl ester, phthalic acid diphenyl ester, phthalic acid di-α-naphthyl ester, phthalic acid dibenzyl ester and the like. Monomers such as 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl acryloyl phosphate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl derivative acrylate, dicyclopentenyl Acrylate, dicyclopentenyloxyethyl acrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, hydroxybivalic acid Bifunctional monomers such as ester neopentyl glycol diacrylate and tripropylene glycol diacrylate, Chi triacrylate, pentaerythritol triacrylate, include trifunctional monomers such as dipentaerythritol hexaacrylate.

  On the other hand, examples of the photopolymerization initiator include, but are not particularly limited to, radical photopolymerization initiators. Examples of the radical photopolymerization initiator include the following. For example, as an alkylphenone photopolymerization initiator, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propane -1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2 -Hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one, 2-methyl-1- (4-tylthiophenyl) -2-morpholinopropan-1-one, 2 -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2- (dimethylamino) -2-[(4-methylphenyl) methyl -1- [4- (4-morpholinyl) phenyl] -1-butanone and the like, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis ( 2,4,6-trimethylbenzoyl) -phenylphosphine oxide and the like, and titanocene photopolymerization initiators include bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro). -3- (1H-pyrrol-1-yl) -phenyl) titanium and the like. As other photopolymerization initiators, 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], which is an oxime ester compound, ethanone, 1- [9-ethyl-6- (2-Methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime) or oxyphenylacetic acid ester compound 2- [2-oxo-2-phenylacetoxyethoxy] ethyl Examples thereof include esters and oxyphenylacetic acid 2- (2-hydroxyethoxy) ethyl ester. In general, these radical photopolymerization initiators are usually mixed and used, and sometimes used in combination with benzophenone or the like.

  In addition, the UV metallic coating composition and the UV metallic ink composition of the present invention include, as necessary, organic pigments such as quinacridone red, phthalocyanine blue, phthalocyanine green, isoindolinone yellow, carbon black, perylene, azo lake, oxidation Inorganic pigments such as iron, titanium oxide, cobalt blue, zinc white, ultramarine, chromium oxide, mica, yellow lead, anti-settling agent, thickener, static eliminating agent, dispersant, antioxidant, polish, surface activity Agents, synthetic preservatives, lubricants, fillers (reinforcing agents), waxes, antifoaming agents, leveling agents, stabilizers and the like may be added. Furthermore, an acidic phosphate ester, nitrocellulose, a carbodiimide compound, or the like may be added.

  Examples of the method of applying or painting using the UV metallic coating composition include a method of applying with a brush, a doctor blade, a roll coater, a bar coater or the like, a method of applying with a spray or the like.

  Examples of the printing method using the UV metallic ink composition include known printing methods such as intaglio printing such as gravure printing, offset printing (transfer printing), screen printing, flexographic printing, other letterpress printing, and lithographic printing. Etc. Moreover, the UV metallic ink composition of the present invention can also be suitably used for inkjet printing.

  About the coating film by UV metallic paint composition and UV metallic ink composition which mix | blends the metal pigment of this invention, it may be formed on the undercoat layer or intermediate coating layer by electrodeposition coating etc. A top coat layer may be formed on the film. The top coat layer may be of any type, such as UV, solvent, and water.

  Although the thickness of the said coating film is not specifically limited, In general embodiment, it is preferable that it is 1 micrometer or more, and if it is 5 micrometers or more, it is more preferable. The thickness is preferably 100 μm or less, more preferably 30 μm or less.

  When the thickness is less than 1 μm, the concealing effect of the base by the ink or paint tends to be insufficient, and when the thickness exceeds 100 μm, the transmission of ultraviolet rays becomes insufficient, and the site is weakly cured in the coating film. There is a risk of occurrence. In addition, since drying becomes difficult, defects such as armpits and sagging tend to increase.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Example 1>
A solution obtained by reacting hydrogen peroxide with metallic molybdenum by adding 0.3 g of metallic molybdenum powder to 3 g of hydrogen peroxide containing 30% by mass of hydrogen peroxide little by little was added to isopropyl alcohol (hereinafter abbreviated as IPA). ) Dissolved in 500 g. Furthermore, 40 g of aluminum particles (trade name: “5422NS”, manufactured by Toyo Aluminum Co., Ltd., solid content: 75 mass%, average particle size: 19 μm) as metal particles were added to this solution as a slurry, This slurry was stirred and mixed at 75 ° C. for 1 hour to form an underlayer, which is a layer containing molybdenum, on the metal particles.

  Thereafter, ammonia water and 80 g of water were added to the slurry, and the pH of the slurry was adjusted to 10. To this slurry whose pH was adjusted, 40 g of tetraethoxysilane (hereinafter referred to as TEOS) dissolved in 40 g of IPA was gradually added dropwise, and further stirred and mixed at 75 ° C. for 2 hours. Next, the obtained slurry is subjected to solid-liquid separation with a filter, and further, the remaining IPA and ammonia are removed, and the slurry is dried at 120 ° C. for 12 hours in order to dehydrate the hydrate in the amorphous silica. Then, a powdery metal pigment (aluminum pigment) in which the surface of the metal particles having the base layer was coated with amorphous silica (first coating) was obtained (solid content: 100 parts by mass). As a result of quantifying the silicon content of the obtained metal pigment by plasma emission analysis, the silicon content was 15.7 parts by mass with respect to 100 parts by mass of the metal particles (aluminum particles). Moreover, it was about 60 nm when the thickness of the 1st film was measured by direct observation by TEM.

  Using the metal pigment thus obtained, a UV metallic coating composition was prepared in accordance with “Composition of UV metallic coating composition” described later, and storage stability was evaluated. The results are shown in Table 1.

<Example 2>
In the same manner as in Example 1, a slurry in which an underlayer that is a layer containing molybdenum was formed on metal particles was obtained. Monoethanolamine was added to this slurry to adjust the pH value of the slurry to 8.5.

  Next, the slurry adjusted to pH was stirred at 50 ° C. for 6 hours while slowly adding dropwise 40 g of TEOS dissolved in 40 g of IPA. Next, 2 g of decyltrimethoxysilane was added to the slurry, and the mixture was further stirred at 50 ° C. for 4 hours. The pH value of the slurry was checked every 2 hours along the way, and the pH value was adjusted to 8.5 by adding monoethanolamine.

  After completion of the above reaction, the slurry is subjected to solid-liquid separation with a filter, and the resulting slurry containing the metal pigment is dried at 120 ° C. for 12 hours, whereby the surface of the metal particles having the base layer is made of amorphous silica (first And a surface of the first film was treated with a silane coupling agent to obtain a powdered metal pigment (aluminum pigment) (solid content: 100 parts by mass). As a result of quantifying the silicon content of the obtained metal pigment by plasma emission analysis, the silicon content was 14.5 parts by mass with respect to 100 parts by mass of the metal particles (aluminum particles). Moreover, it was about 55 nm when the thickness of the 1st film was measured by direct observation by TEM.

  Using the metal pigment thus obtained, a UV metallic coating composition was prepared in accordance with “Composition of UV metallic coating composition” described later, and storage stability was evaluated. The results are shown in Table 1.

<Comparative Example 1>
As a metal pigment, commercially available aluminum particles (trade name: “5422NS”, manufactured by Toyo Aluminum Co., Ltd., solid content: 75% by mass, average particle size: 19 μm) were used, according to “Composition of UV metallic coating composition” described later. UV metallic coating compositions were prepared and evaluated for storage stability. The results are shown in Table 1.

<Comparative example 2>
With respect to 133 g (100 g as an aluminum content) of commercially available aluminum particles (trade name: “5422NS”, manufactured by Toyo Aluminum Co., Ltd., solid content: 75 mass%, average particle size: 19 μm), 2 g of butyl acid phosphate as a surface treatment agent The mixture was added and mixed for 30 minutes with a kneader mixer to prepare a surface-treated aluminum paste.

  30 g of a solution obtained by dissolving 10 parts by mass of nitrocellulose in 90 parts by mass of acrylic acid-2-hydroxy-3-phenyloxypropyl is mixed with 135 g of the obtained surface-treated aluminum paste, and mixed with a kneader mixer for 30 minutes. An aluminum pigment composition (metal content 60 parts by mass) was obtained.

Using the obtained aluminum pigment composition (the surface of aluminum particles coated with nitrocellulose) as a metal pigment, a UV metallic paint composition is prepared and stored in accordance with “Composition of UV metallic paint composition” described later. Stability was evaluated. The results are shown in Table 1.
<Formulation of UV metallic coating composition>
Ingredient Mass part Oligomer (EA-5720) 30
2. DPHA 20
3. TMPTA 30
4). Irgacure 184 3
5. Irgacure 754 2
6). Irgacure 819 1
7). Metal pigment (solid content) 14
Details of each component during the blending are as follows.

1. Oligomer (EA-5720): trade name “NK Oligo EA-5720” (diglycerin polyglycidyl ether acrylate), manufactured by Shin-Nakamura Chemical Co., Ltd. 2. DPHA: dipentaerythritol hexaacrylate, manufactured by Kyoeisha Chemical Co., Ltd. 3. TMPTA: trimethylolpropane triacrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd. 4. Irgacure 184: hydroxycyclohexyl phenyl ketone, manufactured by Ciba Specialty Chemicals Co., Ltd. Irgacure 754: Mixture of oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2- (2-hydroxyethoxy) ethyl ester, manufactured by Ciba Specialty Chemicals Co., Ltd. Irgacure 819: Phenylbis (2,4,6-trimethylbenzoyl) -phosphine oxide, manufactured by Ciba Specialty Chemicals Co., Ltd. Metal pigment: Metal pigment obtained in Examples and Comparative Examples In the above, 1 is a UV oligomer, 2 and 3 are UV monomers, and 4 to 6 are photopolymerization initiators.

In Table 1, “paint dispersibility” is a visual evaluation of the dispersibility immediately after production of the UV metallic paint composition. The evaluation criteria are as follows.
A: The metal pigment is well dispersed in the paint and the paint surface has a strong metallic luster.
B: The metal pigment is dispersed in the paint, and the paint surface has a metallic luster.
C: The metal pigment is temporarily dispersed in the paint, but it is not so familiar and the paint surface has no metallic luster.
D: The metal pigment does not completely match the paint, and the paint surface has a gray color.
That is, “A” indicates the best dispersibility, and “D” indicates the worst dispersibility.

  “60 ° C. × 3 days” and “60 ° C. × 7 days” are both evaluations of the storage stability of the UV metallic coating composition, and at 60 ° C. for 3 days and 60 ° C. after the production, respectively. The result when stored (stored) for 7 days is shown. “Solidification” refers to a state in which “gelation” further proceeds and does not exhibit fluidity at all.

  As is apparent from Table 1, the metal pigments of Examples 1 and 2 according to the present invention exhibit better storage stability than the comparative metal pigments, and can be applied without any problem even after storage for a certain period of time. / I was able to paint.

  In other words, the metal pigment of the present invention can suppress the occurrence of gelation even when blended with an ultraviolet curable composition such as a UV metallic paint composition or a UV metallic ink composition, and can be used as a nitrocellulose. It is clear that it has an excellent effect of not involving danger such as ignition and explosion because it does not contain dangerous substances.

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims (5)

A metal pigment for blending into an ultraviolet curable composition,
Metal particles and a first coating covering the surface,
The first film is a metal pigment made of amorphous silica.   The metal pigment according to claim 1, wherein a surface of the first coating is treated with a silane coupling agent.   The said metal pigment is a metal pigment of Claim 1 or 2 with which silicon is contained in 0.01-100 mass parts with respect to 100 mass parts of said metal particles.   The ultraviolet curable composition which mix | blended the metal pigment in any one of Claims 1-3.   The ultraviolet curable composition according to claim 4, wherein the ultraviolet curable composition is a UV metallic coating composition or a UV metallic ink composition.