JP5242290B2 - Resin-coated aluminum pigment, metallic paint and ink - Google Patents

Description

  The present invention relates to a resin-coated aluminum pigment used as a metallic luster component in metallic coating or ink, and a metallic paint and ink containing the aluminum pigment.

  In this specification and claims, the term “monomer” is used to include monomers and oligomers.

  In recent years, due to growing environmental problems, high solid type paints, water-based paints, powder paints, and the like that have reduced the use ratio of organic solvents have attracted attention as alternatives to conventional solvent-type paints. These paints are also popular in metallic tone, and high quality and high performance are demanded especially as water-based metallic paints.

  However, in the case of a water-based metallic paint, the aluminum pigment blended as a metallic luster component easily reacts with water, so that the aluminum pigment is altered during storage and cannot exhibit a good metallic color tone. There is also a concern that the generated hydrogen swells and deforms or explodes due to the generated hydrogen. On the other hand, from the position as an alternative to solvent-based paints, various properties including chemical resistance, which have been required for solvent-type metallic paints, are also required for water-based metallic paints.

  Means for improving the storage stability of the aqueous metallic paint include, for example, a method using an organic phosphate (Patent Document 1), a method of covering the surface of aluminum pigment particles with a coating of molybdic acid (Patent Document 2), and aluminum pigment particles. A method of coating the surface of this with silica (Patent Document 3) has been proposed. However, with these methods, the storage stability of the water-based metallic paint is certainly increased, but the aluminum pigment lacks chemical resistance.

  On the other hand, as means for improving the chemical resistance of metal pigments such as aluminum pigments, a method of applying resin coating to pigment particles is generally used (Patent Documents 4 and 5). However, the resin-coated metal pigment has sufficient chemical resistance when used in a solvent-type paint, but has insufficient storage stability when used in an aqueous paint.

  For example, (A) radically polymerizable unsaturated carboxylic acid and / or radically polymerizable double bond can be used as a technique for achieving both the stability in water-based paint and the chemical resistance of the metal pigment in the coating film. At least one selected from phosphoric acid or phosphonic acid mono- or diester and / or a coupling agent having a radical polymerizable double bond, and (B) a single amount having three or more radical polymerizable double bonds And (C) a polymerization initiator, first (A) is added to treat the metal material, and then at least one of (B) and (C) is gradually added to polymerize the resin layer. A resin-coated metal pigment formed on the surface has been proposed (Patent Document 6).

  However, this resin-coated metal pigment cannot be said to be sufficient because the storage stability is evaluated at 50 ° C. and the amount of gas generated for about one day, and in the first place, a highly hydrophilic component is selected as the component (A). In this case, since it is very difficult to dissolve in a hydrophobic solvent, there is a problem that unreacted components remain as a residue and the design of the final coating film is greatly deteriorated. Of course, if a hydrophilic solvent is used, the above-mentioned problem does not occur. However, if the polymerization solvent used in the resin coating step is hydrophilic, precipitation polymerization cannot be performed well, so that the resin coating cannot be sufficiently applied to the surface of the metal pigment. That is, it is necessary to use a hydrophobic solvent in order to successfully perform resin coating by precipitation polymerization, and as a result, the above method cannot balance the chemical resistance and the storage stability in the aqueous metallic paint.

  In addition, as another technique for achieving both the stability in water-based paints and the chemical resistance of the metal pigment in the coating film, a phosphate ester adsorbing metal pigment is brought into contact with a metal pigment in a solution or dispersion of the phosphate ester component. An adsorption step for preparing a polymerization slurry, a preparation step for a slurry for polymerization in which the phosphate adsorbing pigment is dispersed in a polymerization solvent and a polymerization component having a polymerizable double bond is dissolved, and the polymerization component is polymerized. There has been proposed a method for producing a resin-coated metal pigment comprising a coating step of forming a resin coating layer on the surface of a phosphate ester-adsorbed metal pigment (Patent Document 7).

However, this method for producing a resin-coated metal pigment is very disadvantageous in terms of cost because the production process is very long, and the phosphate ester is basically very insoluble in hydrophilic and hydrophobic solvents. Unevenness due to aggregation occurs on the surface of the coating film. If a hydrophilic solvent is used, the phosphate ester is completely dissolved. However, when a hydrophilic solvent is added to the hydrophobic solvent in the resin coating step, reaggregation occurs in the phosphate ester, and the above-mentioned irregularities are generated. It will be. Also, even if no flaws occur, storage stability is insufficient due to insufficient adsorption of phosphate ester to the surface of the metal pigment, or precipitation polymerization is difficult to proceed, and a solid resin coating is applied to the surface of the metal pigment. It has a problem that it cannot be formed.
JP 61-47771 A International Publication No. WO02 / 031061 Japanese Patent Laid-Open No. 2004-124069 Japanese Patent Laid-Open No. 64-40566 JP 2005-146111 A International Publication WO 96/38506 JP 2007-119671 A

  The present invention solves the above-mentioned problems, has excellent storage stability (storage stability) when used in a metallic paint such as a water-based paint and chemical resistance of the paint film, and has a good metallic paint film appearance. It aims at providing the resin coating aluminum pigment which can be provided.

  As a result of intensive studies to achieve the above object, the present inventors have coated the surface of aluminum pigment particles with a copolymer containing a specific organophosphate component as one of the copolymer components, and Then, the water-based metallic paint using the resin-coated aluminum pigment exhibits excellent storage stability, and the coating film exhibits a good metallic tone and can exhibit high chemical resistance. It came to make. That is, the present invention provides the following means.

  [1] The particle surface of the aluminum pigment has the following general formula (I) as one of the copolymer components:

(Wherein R ₁ and R ₂ represent a hydrogen atom or a methyl group, and n is a number average in the range of 3 to 40) and are coated with a copolymer containing a phosphate ester component A resin-coated aluminum pigment.

[2] The resin-coated aluminum pigment according to item 1, wherein R ₁ and R ₂ in the general formula (I) are both methyl groups.

  [3] The resin-coated aluminum pigment according to item 1 or 2, wherein the copolymer contains, as a copolymerization component, the phosphate ester component and a monomer having at least one radical-reactive double bond. .

  [4] A metallic paint comprising the resin-coated aluminum pigment according to any one of items 1 to 3.

  [5] An ink comprising the resin-coated aluminum pigment according to any one of items 1 to 3.

  According to the invention of [1], it can be used for both solvent-based paints and water-based paints, and when used in water-based paints, it has excellent storage stability, coating film adhesion, chemical resistance, Thus, it is possible to provide a resin-coated aluminum pigment capable of forming a metallic paint film having a very high design property. The resin-coated aluminum pigment can be easily obtained at low cost by applying a normal resin coating method to the aluminum pigment without requiring any special device, stage, or equipment for its production.

According to the invention of [2], the phosphoric acid ester component as a copolymerization component of the coating resin in the resin-coated aluminum pigment is an acid phosphooxypolyoxypropylene glycol monoester wherein R ₁ and R ₂ in the general formula are methyl groups. Since it consists of methacrylate and is easily soluble in a hydrophobic polymerization solvent, the metallic coating film is excellent in design with no defects.

  According to the invention of [3], the coating resin (copolymer) contains, as a copolymerization component, the phosphate ester component and a monomer having at least one radical-reactive double bond. The chemical resistance and design properties (appearance) of the coating film can be further improved.

  According to the invention of [4], a metallic paint that is excellent in adhesion and chemical resistance of a coating film and can form a metallic paint film having extremely high design properties is provided.

  According to the invention of [5], an ink which is excellent in ink adhesion and chemical resistance and capable of performing metallic tone printing with extremely high design properties is provided.

  As the aluminum pigment used in the present invention, any of conventionally known pigments for metallic paints can be used, but in general, flakes are used.

  As the flaky aluminum pigment, those having an average particle diameter of 2 to 80 μm and an average thickness of 0.03 to 3 μm are suitable for forming a metallic coating film excellent in brightness and denseness. is there. However, when the average particle diameter exceeds 80 μm, an aluminum pigment protrudes from the coating film, or pigment particles in the coating film are conspicuous, and good metallic design is liable to be impaired. The average particle size of the aluminum pigment is usually determined by a laser diffraction method. The thickness of the particle is calculated from WCA [water surface diffusion area (square meter / gram)] and the average particle diameter.

  The aluminum pigment used in the present invention is generally supplied as an aluminum paste flaked by ball milling. This aluminum paste contains fatty acids such as oleic acid and stearic acid added as grinding aids, but these fatty acids maintain the surface gloss as an aluminum pigment and facilitate resin coating by appropriate precipitation polymerization. Therefore, the content is preferably 2% by mass or less based on the aluminum metal. In addition, various colorants such as quinacridone, diketopyrrolopyrrole, and perylene may be attached to the surface of the aluminum pigment for surface coloring.

  In the present invention, in order to uniformly adsorb the phosphate ester component containing a reactive phosphate mono- and / or diester having a radical polymerizable double bond serving as an anchor of the coating resin on the surface of the aluminum pigment particle, It is characterized by using a phosphate ester component having a long ester chain, which is easily soluble in a hydrophobic organic solvent by increasing the molecular weight, instead of the phosphate ester component that is hardly soluble or insoluble in the organic solvent. This can provide a resin-coated aluminum pigment that can maintain a good balance of water resistance, chemical resistance, adhesion, and design (excellent appearance) when formed into a paint or coating film.

  That is, in the present invention, the phosphate group of the phosphate ester uniformly adsorbed on the surface of the aluminum pigment particles functions to prevent corrosion of aluminum in the aqueous paint, and the ester group of the phosphate ester is based on the long ester chain. It is presumed that the steric hindrance due to flexibility suppresses the penetration of the corrosive liquid into the surface of the aluminum pigment particles. Also, phosphoric acid ester molecules with long ester chains and large molecular weights are increased in hydrophobicity and easily dissolved in hydrophobic organic solvents, thus preventing aggregation of unreacted components. Therefore, metallic paints using this resin-coated aluminum pigment are used. The coating film of this will express the outstanding design property. In addition, the resin coating layer of the aluminum pigment improves the chemical resistance of the aluminum particles in the coating film, and adheres between the binder component of the coating film and the aluminum pigment particles due to the flexibility based on the long ester chain. Has the role of strengthening sex.

  The phosphate ester component used in the present invention functions as an anchor for resin coating on the surface of the above-described aluminum pigment particles, and at the same time constitutes a part of the resin that coats the aluminum pigment particles as a copolymerization component, The following general formula (I);

(Wherein, R ₁ and R ₂ represent a hydrogen atom or a methyl group, and n is a number average in the range of 3 to 40) and a phosphoric acid monoester having a radical polymerizable double bond represented by: / Or a diester.

Typical examples of such a phosphate ester component include acid phosphooxypolyoxyethylene glycol monomethacrylate and acid phosphooxypolyoxypropylene glycol monomethacrylate. Among these, acid phosphooxypolyoxypropylene glycol monomethacrylate, in which R ₁ and R ₂ in the general formula (I) are methyl groups, is a chemical resistance, adhesion, and design property ( It is particularly preferable because it is more excellent in appearance.

  When n in the general formula (I) is less than 3, it becomes hardly soluble in the hydrophobic solvent used during the polymerization of the coating resin, and a large amount of unreacted phosphoric acid ester remains and becomes a surface of the metallic coating film. Adversely affect. This is presumably because the hydrophilicity of the phosphate group is too strong. On the other hand, if n in the general formula (I) exceeds 40, the molecular weight as the phosphate ester component is too large, and the phosphate concentration is relatively lowered, so that sufficient anchoring effect to develop water resistance is obtained. There is a problem that the molecular weight of the ester chain is increased and the adhesion to the coating film is deteriorated. In order to obtain a particularly excellent coating film appearance, n in the general formula (I) is preferably in the range of 3 to 30 on the number average, and more preferably in the range of 4 to 20 on the number average.

  The phosphoric acid ester component of the general formula (I) may be one kind or a mixture of two or more kinds. Moreover, it may contain a small amount of phosphoric acid mono- and / or diester which does not have a radical polymerizable double bond as a normal impurity or a new additive component.

  In order to obtain the resin-coated aluminum pigment of the present invention, the phosphate ester component represented by the above general formula (I) is used as it is, mixed with a solvent, or first emulsified with a surfactant in an aluminum pigment slurry. A resin layer that is tightly adhered to the surface of the aluminum pigment particles by using the double bond of the phosphate ester component and copolymerizing with another copolymerizable component having a radical reactive double bond. To form.

  In addition, the appearance of the metallic coating film is better when the phosphate ester component represented by the general formula (I) is mixed with a surfactant in advance and emulsified, rather than mixed with a solvent as it is. This is preferable. If this emulsion is further diluted with a solvent and used, the stability of the liquid is improved, and the handleability is markedly improved due to a decrease in the viscosity of the liquid. The introduction into the aluminum pigment slurry is not particularly required to take time, and may be performed at once.

  The amount of the phosphoric acid ester component of the general formula (I) is preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the aluminum pigment. If the amount used is less than 0.1 parts by weight, the storage stability of the metallic paint is lowered. On the other hand, if the amount used exceeds 10 parts by weight, the storage stability of the metallic paint is sufficient, but aggregation of the aluminum pigment tends to occur and the design of the coating film tends to deteriorate.

  As the other copolymerization component that forms a copolymer of the coating resin together with the phosphate ester component of the general formula (I), a monomer (including an oligomer) containing at least one radical-reactive double bond is preferable. Specific examples thereof include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, benzyl methacrylate, glycidyl methacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane trimethacrylate, lauryl acrylate, butoxyethyl acrylate, Methacrylic acid esters such as 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, acrylic acid esters, Ren, alpha-methyl styrene, divinylbenzene, polybutadiene, epoxidized polybutadiene and the like, used as a mixture of two or more thereof.

  Moreover, it is preferable that the coating resin layer in the resin-coated aluminum pigment of the present invention has a three-dimensional crosslinked structure. Therefore, it is preferable to select one having at least two reactive double bonds in the molecule as at least one copolymerization component.

  The coating amount of the copolymer is preferably 0.5 to 40 parts by weight with respect to 100 parts by weight of the aluminum pigment. If the coating amount is less than 0.5 parts by weight, it is difficult to sufficiently improve the adhesion and chemical resistance. Conversely, if it exceeds 40 parts by weight, the design properties of the metallic coating film deteriorate.

  When performing resin coating by copolymerization on the particle surface of the aluminum pigment, it is desirable to use a polymerization initiator in order to increase reaction efficiency. As the polymerization initiator, those generally used for radical polymerization can be used. For example, peroxides such as isobutyl peroxide and lauroyl peroxide, azobisisobutyronitrile, azobisdimethylvaleronitrile and the like can be used. Representative examples include azo compounds.

  The amount of the polymerization initiator used is required to be 0.1 parts by weight or more, more preferably 0.4 parts by weight or more with respect to 100 parts by weight of the total amount of the copolymerization components. However, when it is used in an amount of 100 parts by weight or more, the polymerization proceeds rapidly but the tendency of the resin coating layer to become weak is remarkable.

  In order to produce the resin-coated aluminum pigment of the present invention, first, an untreated aluminum pigment is uniformly dispersed in a hydrophobic polymerization solvent, and then has a radical polymerizable double bond represented by the general formula (I). Phosphoric acid ester component containing phosphoric acid mono and / or diester, or its diluted mixture with hydrophobic solvent, or its emulsion containing surfactant, and other copolymer containing at least one radical reactive double bond One or more components are added almost simultaneously and the system is heated to a predetermined polymerization temperature while stirring and mixing, or the former containing the phosphate ester component represented by the general formula (I) is added first, After raising the system to the polymerization temperature, the other other copolymer components are added, and the polymerization is started by adding a polymerization initiator to precipitate the copolymer resin on the surface of the aluminum pigment particles. Bayoi.

  When the untreated aluminum pigment is dispersed in the polymerization solvent, the aluminum concentration in the aluminum pigment slurry is desirably 1 to 30% by mass. If the aluminum concentration is less than 1% by mass, a uniform slurry can be obtained, but the amount of the polymerization solvent to be handled is enormous, which is undesirable in terms of both cost and labor. Conversely, when the aluminum concentration exceeds 30% by mass, it is difficult to obtain a uniform pigment slurry.

  In general, the polymerization temperature in the resin coating step is suitably from 60 ° C to 150 ° C. In this polymerization step, in order to maintain an efficient polymerization reaction, it is recommended to replace the air in the polymerization system with an inert gas such as nitrogen. The polymerization time is preferably 1 to 24 hours, and more preferably 2 to 8 hours in terms of cost.

  Preferred solvents used for the polymerization include alkanes such as hexane, heptane, octane, and nonane, isomers thereof, cycloalkanes, isomers thereof, mixtures thereof, and the like, and may contain aromatic compounds. good. Industrially desirable polymerization solvents are industrial gasoline No. 4 and industrial gasoline No. 5 specified in JIS K2201, and aliphatic hydrocarbons called mineral spirits are used because of cost, ease of precipitation polymerization, safety, and the like. Is preferred.

  Thus, the slurry containing the aluminum pigment coated with the resin by copolymerization is made into a paste by removing the solvent to some extent by an appropriate method such as filtration.

  To the obtained resin-coated aluminum pigment paste, additives such as pigments, dyes, wetting agents, dispersants, anti-coloring agents, leveling agents, slip agents and the like that are generally used in the paint field can be added. Further, in order to further increase the storage stability, general phosphate esters may be added.

  The resin-coated aluminum pigment paste may be replaced with a hydrophilic solvent from one containing a polymerization solvent by general solvent replacement. Examples of the hydrophilic solvent include butyl carbitol, isopropyl alcohol, butyl cellosolve, propylene glycol monomethyl ether, diacetone alcohol and the like.

  The coating film of the metallic paint using the resin-coated aluminum pigment of the present invention exhibits extremely excellent chemical resistance. This is presumably because the particle surface of the aluminum pigment is coated with a strong resin layer, so that it is difficult to reach the aluminum surface even when the chemical solution enters the coating film.

  The resin-coated aluminum pigment of the present invention can be applied to water-based paints in combination with a resin for water-based paints. Here, the resin for water-based paints means a water-soluble resin, a water-dispersible resin, and an aqueous emulsion resin, and generally includes a resin for water-based paints such as acrylic, acrylic-melamine, polyester, and polyurethane.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited to the structure of these Examples. In the following, “%” means mass%.

[Calculation of WCA (water surface diffusion area: m ² / g)]
It was measured by the method described in 8.6 of JIS K5906-1998.

[Method of evaluating storage stability (storage stability)]
The obtained paste containing the resin-coated aluminum pigment was reslurried with butyl carbitol having three times the nonvolatile content contained in the paste, and filtered to replace the aluminum pigment with butyl carbitol having a nonvolatile content of 50%. A paste was prepared, and 6.5 g of butyl cellosolve was further mixed with 6.5 g of this paste. Next, a mixture of 50 g of acrylic emulsion paint (Polysol AP7010N manufactured by Showa Polymer Co., Ltd.), 7.5 g of dipropylene normal butyl ether and 12.5 g of deionized water is added to this aluminum pigment paste and stirred well. A water-based paint was prepared by 25 g of this water-based paint was put in a test tube, a gas collecting tube was attached to the test tube, and this was set in a constant temperature water bath at 50 ° C., and the cumulative amount of hydrogen gas generated after 336 hours (14 days) (cm ³ / Aluminum 1g) was measured. And the thing whose hydrogen gas accumulated generation amount (cm < ³ > / aluminum 1g) is less than 10 was set as the pass.

[Preparation method of painted plate]
Using Kansai Paint's automatic coating machine Resicoater and Iwata's spray gun WA-100, water-based paint was spray-coated on an ABS resin plate to a dry film thickness of 15 μm, and allowed to stand at room temperature for 20 minutes. It dried for 20 minutes in the 60 degreeC air oven, and obtained the coating board.

[Method for evaluating surface condition (design) of coating film]
Visually observe the above-mentioned coated plate, `` ○ '' if there is no solid on the painted surface, `` △ '' if there is a slight but not a problem, `` × '' It was evaluated in three stages.

[Adhesion evaluation method]
The cellophane tape made by Nichiban Co., Ltd. having a width of 24 mm was applied to the coating film of the above-mentioned coated plate, and then peeled off. In accordance with the cellophane tape peeling operation, the adhesion of the coating film was evaluated in the following three stages according to the amount of the aluminum pigment in the peeled coating film. That is, “◯” indicates that it is not peeled off at all, “Δ” indicates that it is slightly peeled, and “x” indicates that it is peeled off entirely.

[Chemical resistance evaluation method]
A part of the coated plate was immersed in a 5% aqueous sodium hydroxide solution at room temperature for 24 hours. The color difference between the immersed part and the non-immersed part was measured with a spectrocolorimeter CM-3700d manufactured by Minolta. When this value exceeds 0.5, it is a discoloration that can be visually confirmed, and chemical resistance is insufficient.

(Preparation of resin-coated aluminum pigment)
<Example 1>
214 g of aluminum pigment paste containing aluminum flakes and mineral spirits (Sap CS430, nonvolatile content 70.0%, average particle size 9.0 μm, WCA: 15000 m ² / g manufactured by Showa Aluminum Powder Co., Ltd.) is placed in a 2000 mL separable flask and minerals An aluminum pigment slurry was dispersed in 1050 g of spirit. On the other hand, in a 50 mL beaker, 7.5 g of polyoxyethylene lauryl ether (trade name Emulgen E108 manufactured by Kao Corporation) was added to acid phosphate phosphooxypolyoxypropylene glycol monomethacrylate (n in the above general formula (I)). No. 5-6, Unichemical Corporation trade name Phosmer PP) 1.5 g, stirred using a glass rod, and 9.0 g of mineral spirit was added and stirred to obtain an emulsion. This emulsion was added to the aluminum pigment slurry, and further 12.2 g of epoxidized polybutadiene (trade name Adekaiser BF-1000 manufactured by Adeka Co., Ltd.), trimethylolpropane triacrylate (trade name Light Acrylate TMP- manufactured by Kyoeisha Chemical Co., Ltd.) A) 7.0 g and divinylbenzene (trade name DVB-570 manufactured by Nippon Steel Chemical Co., Ltd.) 2.0 g are added, and azobisbutyronitrile (trade name ABN-R manufactured by Nihon Finechem Co., Ltd.) 0 .75g was added, the temperature was raised to 80 ° C while flowing a small amount of nitrogen gas inside, stirring was continued for 6 hours, the reaction was completed, the cake was washed with filter paper and mineral spirit, the concentration was adjusted with mineral spirit, aluminum A paste containing 49.9% was obtained. The resin yield was 80.5%.

<Example 2>
Except that 1.5 g of acid phosphooxypolyoxypropylene glycol monomethacrylate (n in the general formula (I) is 10 to 14, trade name Shipomer PAM200 manufactured by Rhodia Nikka Co., Ltd.) was used as the phosphate ester component. In the same manner as in Example 1, a paste containing 50.1% aluminum was obtained. The resin yield was 82.0%.

<Comparative Example 1>
Except for using 1.5 g of 2-methacryloyloxyethyl acid phosphate (the one in which n is 1 in the general formula (I), trade name Light Ester P-1M manufactured by Kyoeisha Chemical Co., Ltd.) as the phosphate ester component In the same manner as in Example 1, a paste containing 50.6% of aluminum was obtained. The resin yield was 81.3%.

  As is apparent from the results in Table 1, the resin-coated aluminum pigments of the present invention (Examples 1 and 2) have sufficient storage stability even in water-based paints. Furthermore, the adhesion, surface state, Excellent in both chemical properties.

  On the other hand, even when a phosphate ester is used as the copolymerization component of the coating resin, when the ester chain is short (Comparative Example 1), the hydrophilicity of the phosphate ester is too strong to disperse sufficiently. It can be seen that the phosphoric acid ester of the reaction becomes dull and the surface state of the metallic coating does not reach a satisfactory level.

Claims (5)

The particle surface of the aluminum pigment has the following general formula (I) as one of the copolymerization components:

(Wherein R ₁ and R ₂ represent a hydrogen atom or a methyl group, and n is a number average in the range of 3 to 40) and are coated with a copolymer containing a phosphate ester component A resin-coated aluminum pigment. The resin-coated aluminum pigment according to claim 1, wherein R ₁ and R ₂ in the general formula (I) are both methyl groups.   The resin-coated aluminum pigment according to claim 1 or 2, wherein the copolymer contains, as a copolymerization component, the phosphate ester component and a monomer having at least one radical-reactive double bond.   A metallic paint comprising the resin-coated aluminum pigment according to any one of claims 1 to 3.   An ink comprising the resin-coated aluminum pigment according to any one of claims 1 to 3.