Coated zinc particles, method for manufacturing coated zinc particles, and rust preventive coating composition

Abstract

Provided are coated zinc particles, a method for manufacturing coated zinc particles, and a rust preventive coating composition, wherein at least a portion of the surfaces of (A) zinc particles and / or zinc alloy particles is coated with (B) a vanadium-containing particulate deposit, and the ratio of the content of vanadium atoms to the total amount of the content of component (A) and the content of component (B) is 7000-25000 mass ppm.

Description

Coated zinc particles, method for producing coated zinc particles, and anti-rust paint composition

[0001] The present invention relates to coated zinc particles, a method for producing coated zinc particles, and an anti-rust coating composition.

[0002] In recent years, metal anticorrosion paints containing metal powders such as zinc pigments and aluminum powder as anticorrosion pigments have been used for painting automotive fasteners, etc. Such anticorrosion paints are expected to have the advantage of being highly safe, as they do not suffer from the risk of hydrogen embrittlement in the painted object during the painting process that occurs with conventional zinc plating.

[0003] Anti-rust paints include solvent-based paints containing organic solvents as solvents and water-based paints containing water, but water-based paints are preferred from the viewpoints of preventing accidents caused by ignition of organic solvents, reducing worker exposure, and reducing the environmental load. Furthermore, even in water-based paints, there is a trend toward reducing the organic solvent content.

[0004] Regarding such technology, for example, Patent Document 1 discloses a resin-coated metal powder in which at least a portion of the surface of a metal powder is coated with a hydrolyzable resin as an additive for an aqueous coating composition.

[0005] Patent Document 2 discloses a method for producing a metal-containing powder water-based paint, which contains a substance obtained by hydrolyzing a silane oligomer having both an epoxy group and an alkoxy group in the presence of a catalyst.

[0006] JP 2022-7869 A International Publication No. 2007 / 111769

[0007] However, resin-coated metal powders, in which the surface of metal powder is coated with a hydrolyzable resin, have the problem that the hydrolyzable resin may peel off from the metal surface after a certain period of time.

[0008] Furthermore, in order to prepare a coating material containing a substance obtained by hydrolyzing a silane oligomer having both epoxy and alkoxy groups in the presence of a catalyst, it is necessary to perform complicated operations such as hydrolyzing the silane using a catalyst, separating the catalyst component after hydrolysis, and continuously removing the alcohol by-product of the hydrolysis reaction.

[0009] On the other hand, as mentioned above, aqueous coating compositions are being developed to reduce environmental impact, but there is room for improvement. For example, the present inventors have hypothesized that the reaction between zinc, zinc alloys, etc. and water may increase the amount of hydrogen gas generated during storage of aqueous coating compositions containing metal particles such as zinc and zinc alloys. The present inventors also hypothesized that an increase in the amount of hydrogen gas generated could lead to deterioration of the anti-rust pigment contained in aqueous coating compositions containing metal particles such as zinc and zinc alloys before application. Furthermore, the present inventors have hypothesized that the generated hydrogen gas could increase the internal pressure of containers storing aqueous coating compositions containing metal particles such as zinc and zinc alloys, thereby raising safety concerns. This problem is particularly pronounced in aqueous coating compositions with a high water content. Based on this insight, the present inventors have attempted to develop an anti-rust pigment that is stable in solvents containing water.

[0010] The present invention has been made in view of the above circumstances, and aims to provide coated zinc particles that have excellent stability and dispersibility in aqueous solvents, a method for producing coated zinc particles, and an anti-rust coating composition.

[0011] As a result of intensive research into achieving the above-mentioned object, the present inventors have discovered the use of coated zinc particles in which at least a portion of the surface of zinc particles and / or zinc alloy particles is coated with a particulate deposit containing vanadium, and have completed the present invention.

[0012] <1> Coated zinc particles, in which at least a portion of the surface of (A) zinc particles and / or zinc alloy particles is coated with (B) a particulate deposit containing vanadium, and the ratio of the content of vanadium atoms to the total content of the (A) component and the (B) component is 7,000 to 25,000 ppm by mass. <2> Coated zinc particles according to the above item <1>, in which the average particle size of the (B) component is 20 to 100 nm. <3> A method for producing coated zinc particles according to the above item <1> or <2>, comprising the step of contacting at least a portion of the surface of the (A) zinc particles and / or zinc alloy particles with an aqueous solution containing (C) at least one compound selected from the group consisting of metavanadate, vanadate, and vanadium oxysulfate, thereby coating at least a portion of the surface of the (A) component with (B) a particulate deposit containing vanadium. <4> The method for producing coated zinc particles according to the above item <3>, wherein the content of the compound in the component (C) is 0.28 to 1.6 mol / L in terms of vanadium atoms. <5> The method for producing coated zinc particles according to the above item <3> or <4>, wherein the pH of the aqueous solution is 2 to 12. <6> An anti-corrosion coating composition comprising the coated zinc particles according to the above item <1> or <2>, a binder, and water. <7> The anti-corrosion coating composition according to the above item <6>, further comprising an organic solvent. <8> The anti-corrosion coating composition according to the above item <6> or <7>, wherein the binder comprises at least one selected from the group consisting of silane-based binders, titanium-based binders, zirconium-based binders, and organic binder resins. <9> The anti-corrosion coating composition according to any one of the above items <6> to <8>, wherein the total content of solvents in the anti-corrosion coating composition is 30 to 85 mass%. <10> The anticorrosive coating composition according to any one of <6> to <9> above, wherein the content of the water in the anticorrosive coating composition is 25 to 70 mass %.

[0013] According to the present invention, it is possible to provide coated zinc particles having excellent stability and dispersibility in aqueous solvents, and an anticorrosive coating composition containing the coated zinc particles. Furthermore, according to the present invention, it is possible to provide a simple method for producing the coated zinc particles.

[0014] FIG. 1 is a graph showing the results of EDS measurement of the coated zinc particles of Example 1.

[0015] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0016] Furthermore, in this specification, terms with "abbreviation" attached indicate the meaning of the term excluding "abbreviation" within the scope of common technical knowledge of a person skilled in the art, and also include the meaning itself excluding "abbreviation."

[0017] <Coated zinc particles>

[0018] The coated zinc particles according to the present embodiment comprise (A) zinc particles and / or zinc alloy particles, at least a portion of whose surface is coated with (B) a particulate deposit containing vanadium, and the ratio of vanadium atoms to the total content of the (A) component and the (B) component is 7,000 to 25,000 ppm by mass. The use of such coated zinc particles can impart excellent stability and dispersibility when the coated zinc particles are incorporated into water or an aqueous solvent. For example, when zinc particles are incorporated into water or an aqueous solvent, problems such as hydrogen gas generation due to reaction with water and poor dispersibility in water can occur. However, the coated zinc particles according to the present embodiment are believed to be able to effectively suppress hydrogen gas generation due to reaction between zinc particles and / or zinc alloy particles and water, and to exhibit high dispersibility in water, even when incorporated into water or an aqueous solvent. As a result, an anti-corrosion coating composition containing these coated zinc particles can exhibit excellent anti-corrosion performance (although the effects and advantages of the present embodiment are not limited to these).

[0019] The inventors also noted that zinc particles and / or zinc alloy particles may ignite when airborne, and that their sacrificial corrosion protection function may be reduced due to air oxidation during storage. Regarding this issue, some highly active zinc particles and / or zinc alloy particles have their surfaces coated with non-hydrophilic organic substances having long-chain hydrocarbon groups, such as fatty acids, or mineral oil. However, the inventors realized that zinc particles and / or zinc alloy particles coated with such organic substances or mineral oils tend to repel water, and therefore require further improvement in order to be efficiently dispersed in aqueous solvents. The coated zinc particles according to this embodiment have excellent dispersibility and can meet such demands for improvement.

[0020] In the coated zinc particles according to this embodiment, at least a portion of the surface of the zinc particles and / or zinc alloy particles (A) is coated with a particulate deposit containing vanadium (B). For example, it is preferred that the particulate deposit containing vanadium (B) is attached to at least a portion of the surface of the zinc particles and / or zinc alloy particles (A). In the coated zinc particles according to this embodiment, it is preferred that at least a portion of the surface of the component (A) is coated with a coating formed by a particulate deposit containing vanadium. It is also preferred that the coated zinc particles according to this embodiment have a coating formed by the attachment of a plurality of particulate deposits containing vanadium to at least a portion of the surface of the component (A).

[0021] In the coated zinc particles according to this embodiment, the ratio of vanadium atoms to the total content of the (A) component and the (B) component is 7,000 to 25,000 ppm by mass. The lower limit is preferably 8,000 ppm by mass or more, more preferably 9,000 ppm by mass or more, and even more preferably 11,000 ppm by mass or more. The upper limit is preferably 24,000 ppm by mass or less, more preferably 21,000 ppm by mass or less. When the ratio of vanadium atoms is within this range, the (A) zinc particles and / or zinc alloy particles can be sufficiently coated with the (B) vanadium-containing particulate deposit. This more effectively suppresses the generation of hydrogen gas due to the reaction between the coated zinc particles and water when the coated zinc particles are added to water or a solvent containing water, and the coated zinc particles have better dispersibility in water.

[0022] The ratio of vanadium atoms to the total content of the component (A) and the component (B) was calculated from the concentration of vanadium atoms in a solution obtained by dissolving the coated zinc particles in nitric acid, which was determined by ICP emission spectroscopy.

[0023] The particulate deposit containing vanadium (B) that coats the surfaces of the zinc particles and / or zinc alloy particles (A) only needs to coat at least a portion of the zinc particle surface, and the thickness of the coating layer formed by component (B) does not need to be uniform.

[0024] Hereinafter, each component of the coated zinc particles according to this embodiment will be described.

[0025] ((A) Zinc particles and / or zinc alloy particles)

[0026] Component (A) contains zinc particles and / or zinc alloy particles. Examples of zinc particles and / or zinc alloy particles include pulverized, crushed, and particulate zinc and / or zinc alloy particles. The shape of the particles is not particularly limited, and examples include substantially spherical and flaky shapes, with flaky shapes being more preferred. Two or more types of zinc particles or zinc alloy particles with different shapes can also be used in combination.

[0027] When the zinc particles and / or zinc alloy particles are substantially spherical, their average particle size is preferably 20 μm or less, although there are no particular limitations on this. The lower limit is preferably 1 μm or more. The upper limit is more preferably 15 μm or less. This average particle size can be determined by the D50 value of the particle size distribution measured with a laser diffraction particle size distribution analyzer. For example, the average particle size can be measured using a laser diffraction / scattering particle size distribution analyzer "Partica LA-960V2" manufactured by Horiba, Ltd., or a particle size distribution analyzer "Microtrac (registered trademark) MT3000II" manufactured by Microtrac-Bell.

[0028] When the zinc particles and / or zinc alloy particles are not substantially spherical (e.g., when they are flaky), their maximum length (or "major axis" in the case of flakes) is not particularly limited, but it is preferable that at least 50% by mass of the particles of component (A) be 1 μm or more and less than 25 μm. It is also preferable that at least 90% by mass of the particles of component (A) be less than 50 μm. The D50 value of the particle size distribution measured with a laser diffraction particle size analyzer can be used for the maximum length (or "major axis" in the case of flakes). For example, the laser diffraction particle size analyzer can be the one described above.

[0029] Furthermore, when the zinc particles and / or zinc alloy particles are not substantially spherical (for example, when they are flaky), the average thickness of the particles is not particularly limited, but is preferably 0.05 to 1 μm. The lower limit is more preferably 0.1 μm or more. The upper limit is more preferably 0.5 μm or less. This thickness can be measured using an electron microscope.

[0030] The surface condition of zinc particles and / or zinc alloy particles is not particularly limited. For example, the surface of zinc particles and / or zinc alloy particles may be smooth or uneven. For example, the surface of zinc particles and / or zinc alloy particles may be uneven. For example, the surface of zinc particles and / or zinc alloy particles may be subjected to physical treatment such as unevenness formation or rolling, or chemical treatment such as oxidation. By subjecting the zinc particles and / or zinc alloy particles to such physical or chemical treatment, the physical properties of the particles can be modified. For example, the color can be changed, such as blackening, or gloss can be imparted.

[0031] The content of zinc atoms in the zinc particles is not particularly limited, but is preferably high purity, more preferably 99% by mass or more.

[0032] The zinc alloy particles are not particularly limited, and may be particles of an alloy containing zinc. Examples of metals other than zinc that form zinc alloys include aluminum, tin, magnesium, nickel, cobalt, and manganese. Preferred examples of zinc alloys include alloys of zinc and aluminum, alloys of zinc and tin, and alloys of zinc, aluminum, and tin. More preferred examples of the zinc alloy particles according to this embodiment include flakes of a zinc alloy of zinc and aluminum, flakes of a zinc alloy of zinc and tin, and the like.

[0033] The zinc atom content in the zinc alloy particles is not particularly limited, but is preferably 50 mass % or more, more preferably 80 mass % or more, and even more preferably 85 mass % or more. When the zinc atom content in the zinc alloy particles is within this range, the rust-preventing performance of the rust-preventing coating can be further improved.

[0034] More specifically, for example, in a zinc alloy of zinc and aluminum, the zinc atom content is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. Furthermore, in a zinc alloy of zinc and aluminum, the mass ratio of zinc atoms to aluminum atoms (zinc atoms:aluminum atoms) is preferably 80:20 to 99:1, more preferably 85:15 to 99:1, even more preferably 90:10 to 99:1, and even more preferably 95:5 to 99:1. As another specific example, for example, in a zinc alloy of zinc and tin, the zinc atom content is preferably 70% by mass or more, more preferably 80% by mass or more. Furthermore, in a zinc alloy of zinc and tin, the mass ratio of zinc atoms to tin atoms (zinc atoms:tin atoms) is preferably 70:30 to 99:1, more preferably 80:20 to 99:1. When the content of zinc atoms in the zinc alloy particles is within this range, the rust-preventing performance of the rust-preventing coating can be further improved.

[0035] ((B) Particulate deposits containing vanadium)

[0036] Component (B) is a granular deposit containing vanadium. The granular deposit containing vanadium is preferably, for example, a substantially spherical deposit containing vanadium provided on the surface of zinc particles and / or zinc alloy particles. It is also preferable that a plurality of granular deposits containing vanadium adhere to at least a portion of the surface of component (A), thereby forming a coating. Component (B) coats at least a portion of the surface of component (A) (however, the form of component (B) in this embodiment is not limited to these).

[0037] The coated zinc particles preferably have an average particle size of component (B) of 20 to 100 nm. The lower limit of the average particle size of component (B) is more preferably 35 nm or more, and even more preferably 40 nm or more. The upper limit of the average particle size of component (B) is more preferably 80 nm or less, and even more preferably 60 nm or less. This is expected to make it even less likely that hydrogen gas will be generated by reaction with water when the coated zinc particles are added to water or a solvent containing water, and to have better dispersibility in water (however, the effects of this embodiment are not limited to these).

[0038] The average particle size of component (B) was determined by photographing the cross sections of 10 different coated zinc particles by STEM-EELS, measuring the particle sizes of all particulate deposits containing vanadium that were attached to the zinc particles and / or zinc alloy particles within the cross-sectional images, and then averaging the results.

[0039] <Method of manufacturing coated zinc particles>

[0040] A preferred example of the method for producing coated zinc particles according to this embodiment is a production method comprising the step of contacting at least a portion of the surface of (A) zinc particles and / or zinc alloy particles with (C) an aqueous solution containing at least one compound selected from the group consisting of metavanadate, vanadate, and vanadium oxysulfate, thereby coating at least a portion of the surface of component (A) with (B) a particulate deposit containing vanadium.

[0041] ((C) Aqueous Solution Containing at Least One Compound Selected from the Group Consisting of Metavanadate, Vanadate, and Vanadium Oxysulfate)

[0042] Component (C) is an aqueous solution containing at least one compound selected from the group consisting of metavanadate, vanadate, and vanadium oxysulfate. As the vanadium compound, it is preferable to use one or more compounds selected from metavanadate, vanadate, and vanadium oxysulfate, which are water-soluble vanadium compounds. Among these, it is more preferable to use metavanadate.

[0043] Examples of metavanadates include ammonium metavanadate, tetra(n-butyl)ammonium metavanadate, lithium metavanadate, sodium metavanadate, potassium metavanadate, rubidium metavanadate, cesium metavanadate, magnesium metavanadate, calcium metavanadate, strontium metavanadate, barium metavanadate, etc. Among these, it is preferable to use at least one selected from the group consisting of lithium metavanadate, sodium metavanadate, potassium metavanadate, rubidium metavanadate, and cesium metavanadate, and it is more preferable to use sodium metavanadate.

[0044] Examples of vanadates include ammonium vanadate, tetra(n-butyl)ammonium vanadate, lithium vanadate, sodium vanadate, potassium vanadate, rubidium vanadate, cesium vanadate, magnesium vanadate, calcium vanadate, strontium vanadate, barium vanadate, etc. Among these, it is preferable to use at least one selected from the group consisting of lithium vanadate, sodium vanadate, potassium vanadate, rubidium vanadate, and cesium vanadate, and it is more preferable to use sodium vanadate.

[0045] (Method for producing coated zinc particles)

[0046] A preferred example of the method for producing coated zinc particles according to this embodiment includes a production method comprising the steps of contacting at least a portion of the surface of (A) zinc particles and / or zinc alloy particles with an aqueous solution containing (C) at least one compound selected from the group consisting of metavanadate, vanadate, and vanadium oxysulfate, thereby coating at least a portion of the surface of component (A) with (B) a particulate deposit containing vanadium. Stirring or kneading is preferably performed to efficiently contact component (A) with component (C). Examples of methods for this include stirring or kneading using a magnetic stirrer, a stirring blade, a mortar, a water stream, an air stream, or the like. By stirring or kneading, at least a portion of the surface of the zinc particles and / or zinc alloy particles can be coated with a particulate deposit containing vanadium. Therefore, the method for producing coated zinc particles according to this embodiment is simpler than conventional methods. However, the method for contacting component (A) with component (C) is not limited to this method.

[0047] The time (contact time) for contacting component (A) with component (C) is not particularly limited, but is preferably 5 to 180 minutes. The lower limit of the contact time is more preferably 30 minutes or more, and even more preferably 60 minutes or more. The upper limit of the contact time is more preferably 90 minutes or less. By keeping the contact time within this range, at least a portion of the surface of the zinc particles and / or zinc alloy particles can be effectively coated with a particulate deposit containing vanadium. As a result, when these coated zinc particles are added to an aqueous solvent, it is expected that the amount of hydrogen gas generated will be effectively suppressed. Furthermore, these coated zinc particles have better dispersibility in aqueous solvents.

[0048] When the zinc particles and / or zinc alloy particles used as component (A) are coated with a water-repellent substance, the aqueous solution of component (C) preferably contains a hydrophilic organic solvent, a surfactant, etc. Adding a hydrophilic organic solvent, a surfactant, etc. to the aqueous solution can more effectively bring component (A) and component (C) into contact with each other. However, the method for coating the zinc particles and / or zinc alloy particles is not limited to this method.

[0049] The content of the compound in component (C) is preferably 0.28 to 1.6 mol / L in terms of vanadium atoms. The lower limit of the compound content is more preferably 0.41 mol / L or more. The upper limit of the compound content is also preferably the saturation concentration of component (C). For example, when a saturated aqueous solution of sodium metavanadate is used as component (C), the content (saturation concentration) of sodium metavanadate in component (C) is, for example, 1.6 mol / L in terms of vanadium atoms. Furthermore, when a saturated aqueous solution of sodium vanadate is used as component (C), the content (saturation concentration) of sodium vanadate in component (C) is, for example, 1.2 mol / L in terms of vanadium atoms. Furthermore, when a saturated aqueous solution of vanadium oxysulfate is used as component (C), the content (saturation concentration) of vanadium oxysulfate in component (C) is, for example, 3.3 mol / L in terms of vanadium atoms. When a saturated aqueous solution of component (C) is used and precipitation of a water-soluble vanadium compound occurs due to the effects of pH adjustment, etc., it is preferable to remove the precipitate by appropriate procedures such as filtration. By ensuring that the content of the compound in component (C) is within the above range, the surfaces of the zinc particles and / or zinc alloy particles can be more effectively coated with a particulate deposit containing vanadium.

[0050] The pH of the aqueous solution of component (C) is not particularly limited, but is preferably 2 to 12. The pH of the aqueous solution of the water-soluble vanadium compound used to form a coating on the surface of zinc particles can be adjusted as needed, as long as precipitation of the vanadium compound in the aqueous solution does not occur. The upper limit of the pH of the aqueous solution of component (C) is more preferably 10 or less, even more preferably 8 or less, even more preferably 6 or less, and even more preferably 4 or less. When the pH of the aqueous solution is within this range, the resulting coated zinc particles, when incorporated into water or an aqueous solvent, are particularly unlikely to generate hydrogen gas due to reaction with water, and have particularly good dispersibility in the solvent. Furthermore, an anti-corrosion coating composition containing these coated zinc particles has even better corrosion resistance.

[0051] Examples of pH adjusters used to adjust the pH of an aqueous solution include inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, and boric acid; carboxylic acids such as formic acid, acetic acid, propionic acid, citric acid, oxalic acid, lactic acid, malic acid, tartaric acid, and maleic acid; sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid; lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, tetramethylammonium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide. and the like; carbonates such as lithium carbonate, lithium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, rubidium carbonate, rubidium hydrogen carbonate, cesium carbonate, cesium hydrogen carbonate, magnesium carbonate, magnesium hydrogen carbonate, calcium carbonate, calcium hydrogen carbonate, strontium carbonate, strontium hydrogen carbonate, barium carbonate, and barium hydrogen carbonate; and organic amine compounds such as isopropylamine, triethylamine, tripropylamine, tributylamine, and triethanolamine.

[0052] The pH adjusters may be used alone or in combination of two or more.

[0053] In this way, zinc particles and / or zinc alloy particles having a coating of particulate deposits containing vanadium on at least a portion, preferably the entire surface, can be obtained as coated zinc particles. The coated zinc particles can be obtained, for example, as a composition containing coated zinc particles, a hydrophilic organic solvent, a surfactant, water, etc. This composition can be obtained, for example, as a paste. For example, the coated zinc particles can be separated from the obtained paste or composition by filtration or the like, washed with water, and dried for use. Furthermore, for example, the obtained paste or composition containing the coated zinc particles can be used as is in an anti-corrosion coating composition, or, if necessary, after removing the solvent or adding a new solvent.

[0054] <Anti-rust coating composition>

[0055] The anti-rust coating composition according to this embodiment preferably contains coated zinc particles, a binder, and water. The solvent contained in the anti-rust coating composition may be water alone, but preferably further contains an organic solvent. That is, the anti-rust coating composition according to this embodiment is preferably an aqueous coating composition containing water and one or more organic solvents. In this case, the organic solvent is more preferably a hydrophilic organic solvent.

[0056] The organic solvent contained in the anticorrosive coating composition may be the same as that used in the production of the coated zinc particles, i.e., the hydrophilic organic solvent may be contained in a paste or composition containing the coated zinc particles obtained by the production of the coated zinc particles.

[0057] The organic solvent that can be used in the anticorrosive coating composition is not particularly limited, but examples thereof include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, etc., glycol ethers such as monomethyl ether, monoethyl ether, dimethyl ether, diethyl ether of these glycols, alcohols such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, diacetone alcohol, etc., ketones such as acetone, methyl ethyl ketone, etc. Among these, glycols and glycol ethers are preferred.

[0058] The organic solvent may be used alone or in combination of two or more kinds.

[0059] The total content of solvents in the anticorrosive coating composition is preferably 30 to 85% by mass. The lower limit of this content is more preferably 50% by mass or more. The water content in the anticorrosive coating composition is preferably 25 to 70% by mass. The lower limit of the water content is more preferably 30% by mass or more, and even more preferably 35% by mass or more. The upper limit of the water content is more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less. When the solvent contains water and an organic solvent, the water content in the solvent is preferably 50% by mass or more, and the organic solvent content is preferably 50% by mass or less.

[0060] The anticorrosive coating composition preferably further contains a binder. The binder is not particularly limited, and preferably contains, for example, at least one binder selected from the group consisting of silane-based binders, titanium-based binders, zirconium-based binders, and organic binder resins.

[0061] The silane binder is not particularly limited, but examples thereof include silane coupling agents, silicates such as sodium silicate, potassium silicate, and lithium silicate, and alkoxysilanes such as tetramethylsilane and tetraethoxysilane. Among these, silane coupling agents are preferred as the silane binder. Examples of the silane coupling agent include vinylsilane coupling agents such as vinyltrimethoxysilane, acrylicsilane coupling agents such as methacryloxypropyltrimethoxysilane, aminosilane coupling agents such as 3-aminopropyltrimethoxysilane, and epoxysilane coupling agents such as β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane.

[0062] The titanium-based binder is not particularly limited, but examples thereof include polymers such as titanic acid, tetraethyl titanate, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, 2-ethylhexyl titanate, and tetra-n-butyl titanate, and titanium dioxide particles.

[0063] The zirconium-based binder is not particularly limited, but examples thereof include tetrapropoxyzirconium, zirconium tributoxystearate, and zirconium tributoxymonoacetylacetonate.

[0064] The organic binder resin is not particularly limited, but examples thereof include acrylic resin, epoxy resin, phenol resin, polystyrene resin, polyurethane resin, oxazoline group-containing polymer, polyvinylpyrrolidone, and the like.

[0065] The above-mentioned binders may be used alone or in combination of two or more.

[0066] The content of the binder in the anticorrosive coating composition is not particularly limited, but is preferably 3 to 35% by mass. The lower limit of the binder content is more preferably 9% by mass or more, and even more preferably 12% by mass or more. The upper limit of the binder content is more preferably 30% by mass or less, even more preferably 25% by mass or less, and even more preferably 20% by mass or less. By setting the binder content within this range, the coating film of the anticorrosive coating composition exhibits better adhesion to the substrate, and the sacrificial corrosion protection effect of the coated zinc particles in the anticorrosive coating composition works more effectively.

[0067] When a silane-based binder is used, the content of the silane-based binder in the anticorrosive coating composition is not particularly limited, but is usually preferably 3 to 20 mass %. The lower limit is more preferably 4 mass % or more, and the upper limit is more preferably 16 mass % or less.

[0068] The anticorrosive coating composition contains coated zinc particles, but may further contain other metal particles.

[0069] Metal particles other than coated zinc particles (hereinafter sometimes referred to as "other metal particles") are not particularly limited, and examples thereof include metal particles or alloy particles such as aluminum particles or aluminum alloy particles, manganese particles or manganese alloy particles, nickel particles or nickel alloy particles, titanium particles or titanium alloy particles, tin particles or tin alloy particles, iron particles or iron alloy particles, magnesium particles or magnesium alloy particles, cobalt particles or cobalt alloy particles, tungsten particles or tungsten alloy particles, vanadium particles or vanadium alloy particles, molybdenum particles or molybdenum alloy particles, tantalum particles or tantalum alloy particles, niobium particles or niobium alloy particles, and stainless steel particles. The other metal particles may be used alone or in combination of two or more types.

[0070] The shape of the other metal particles is not particularly limited, but is usually preferably approximately spherical or flaky, more preferably flaky. In addition, the other metal particles may have at least a portion of their surface treated with, for example, silica or an aliphatic carboxylic acid.

[0071] The total content of the coated zinc particles and the other metal particles in the anticorrosive coating composition is not particularly limited, but is preferably 10 to 50 mass %.

[0072] The anticorrosive coating composition may further contain, for example, a metal oxide pigment or an organic pigment.

[0073] The metal oxide pigment is not particularly limited, but examples thereof include manganese oxide, molybdenum oxide, tungsten oxide, tin oxide, antimony oxide, iron oxide, aluminum oxide, zinc oxide, magnesium oxide, niobium oxide, vanadium oxide, tantalum oxide, silica, titania, zirconia, silica alumina, silica titania, silica magnesia, etc. The shape of these pigments is not particularly limited, but they are preferably particles (particulate).

[0074] The organic pigment is not particularly limited, but examples thereof include β-naphthol-based pigments, β-oxynaphthoic pigments, pyrazolone-based pigments, acetoacetate arylide-based monoazo pigments, acetoacetate arylide-based disazo pigments, benzimidazolone-based monoazo pigments, isoindolinone-based pigments, styrene-based pigments, isoindoline-based pigments, and phthalocyanine-based pigments.

[0075] The anti-rust coating composition may also contain additives, such as surfactants, thickeners, repair agents (inhibitors), lubricants, dispersants, wetting agents, leveling agents, rheology modifiers, pH adjusters, pH stabilizers, film-forming aids, stabilizers, thixotropes, antifoaming agents, ultraviolet absorbers, flame retardants, preservatives, antistatic agents, and colorants, as required.

[0076] In addition, when coated zinc particles are used to prepare a water-based paint, the dispersibility is excellent and it is usually expected that a practical effect can be obtained without adding a dispersant, but in some cases it is preferable to use a dispersant to stably disperse other metal pigments and additives. For example, by adding a surfactant to the anticorrosive paint composition, the adhesion and leveling properties of the obtained anticorrosive coating can be improved.

[0077] The surfactant is not particularly limited, but examples thereof include nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkylamides, polyoxyethylene higher alcohol ethers, polyoxyalkylene alkyl ethers, polyoxyethylene polyoxypropylene glycols, polyethylene glycol fatty acid esters, glycerin fatty acid esters, propylene glycol fatty acid esters, alkyl glyceryl ethers, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters; cationic surfactants such as mono-, di-, or trialkylamine salts, alkyltrimethylammonium halides, dialkyldimethylammonium halides, and alkyldimethylbenzylammonium chloride; and anionic surfactants such as mono- or dialkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkylphenyl ether phosphates, and dialkyl sulfosuccinates. Among these, nonionic surfactants are preferred as surfactants for use in the anticorrosive coating composition. The surfactants may be used alone or in combination of two or more. Furthermore, the surfactant contained in the anticorrosive coating composition may be a surfactant used during the production of coated zinc particles and contained in the resulting composition.

[0078] The content of the surfactant in the anticorrosive coating composition is not particularly limited, but is usually preferably 0.01 to 10 mass %.

[0079] To adjust the viscosity of the anticorrosive coating composition, for example, a thickener may be added.

[0080] The thickener is not particularly limited, but examples thereof include cellulose-based thickeners such as ethers (cellulose ethers) such as methyl cellulose, hydroxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, ethylhydroxyethyl cellulose, methyl ethyl cellulose, and hydroxypropyl cellulose, cellulose nanofibers, xanthan gum, urethane-based thickeners, acrylic-based thickeners, modified clay, fatty acid salts, and fatty acid amides. Among these, cellulose ethers are preferred as thickeners for use in anticorrosive coating compositions. The thickeners may be used alone or in combination of two or more.

[0081] The content of the thickener in the anticorrosive coating composition is not particularly limited, but is usually preferably 0.005 to 2% by mass.

[0082] The anticorrosion coating composition preferably contains a repair agent (inhibitor). The repair agent that can be added to the anticorrosion coating composition is a compound that can react with the exposed metal or alloy surface of the coated zinc particles of this embodiment or other metal particles when the metal or alloy surface is exposed in the composition to form a coating or modify the surface (repair).

[0083] The repair agent is not particularly limited, but examples thereof include boron compounds such as boric acid, magnesium compounds such as magnesium oxide and magnesium hydroxide, aluminum compounds such as aluminum hydroxide, gallium compounds such as gallium hydroxide, silicon compounds such as sodium silicate, indium compounds such as indium hydroxide, tin compounds such as tin hydroxide, bismuth compounds such as bismuth hydroxide, vanadate compounds such as lithium vanadate, tungstate compounds such as lithium tungstate, molybdate compounds such as potassium molybdate, cerium compounds such as cerium nitrate, phosphates such as potassium phosphate, amine compounds such as polyethyleneimine, silicon compounds such as tetraethoxysilane and silane coupling agents, etc. The repair agents may be used alone or in combination of two or more.

[0084] The method of adding the repair agent is not particularly limited, and it is preferable to add, for example, an anti-rust pigment containing the above-mentioned compound. It is also preferable to add a compound impregnated in or supported by zeolite, cellulose nanofiber, or the like, or a compound encapsulated and enclosed within the compound.

[0085] In addition, the excess water-soluble compound of vanadium used in the production of the coated zinc particles and contained in the resulting paste or composition also functions as a repair agent in the anticorrosive coating composition.

[0086] The content of the repair agent in the anticorrosive coating composition is not particularly limited and can be selected appropriately, but it is usually preferably 10 mass % or less.

[0087] For the purpose of adjusting the coefficient of friction of the surface of the anti-rust coating obtained from the anti-rust coating composition, for example, a lubricant can be added to the anti-rust coating composition of this embodiment.

[0088] The lubricant is not particularly limited, but examples thereof include polyolefins and modified polyolefins (polyethylene, modified polyethylene, polypropylene, modified polypropylene, etc.), waxes such as paraffin, carnauba waxes, fluororesins, melamine cyanurate, hexagonal boron nitride, etc. The lubricants may be used alone or in combination of two or more.

[0089] The content of the lubricant in the anticorrosive coating composition is not particularly limited and can be appropriately selected so as to obtain the desired surface friction coefficient, but it is usually preferably 20 mass % or less.

[0090] The anti-rust coating composition according to this embodiment can be produced by uniformly stirring and mixing the coated zinc particles, or a paste or composition containing the coated zinc particles, with water, a binder, and other coating components, using a commonly used known method.

[0091] (Anti-rust coating and article having anti-rust coating)

[0092] The anticorrosive coating composition according to this embodiment can be suitably used for anticorrosive coatings and articles having the same. Specifically, it is preferable to prepare an anticorrosive coating by drying and / or baking the anticorrosive coating composition according to this embodiment. It is also preferable to prepare an article having an anticorrosive coating on its surface by, for example, applying the anticorrosive coating composition according to this embodiment to an article to be coated, followed by drying and / or baking.

[0093] Metal or alloy materials to which the anticorrosive coating composition can be applied are not particularly limited, but preferred examples include aluminum, aluminum alloys, iron, iron alloys, carbon steel, alloy steel, and stainless steel. Furthermore, preferred substrates for the anticorrosive coating composition include metal or alloy surfaces that have been subjected to surface treatments such as plating, chemical conversion treatments such as oxidation, nitriding, and carbonization, and dry plating. Among these, it is more preferred that the substrate contains iron or an iron alloy, or has a film or layer containing iron or an iron alloy on its surface. Providing such a substrate with an anticorrosive coating further improves corrosion resistance. The substrate to be coated is not particularly limited, and may be a raw material (the metal or alloy material itself), an intermediate product, a final product, or the like.

[0094] The method for applying the anticorrosive coating composition to the substrate is not particularly limited, and any known method can be used. For example, application by a dipping method (immersion method), a dip spin method (immersion method accompanied by centrifugal shaking), a spray coating method, a spin coating method, or the like is preferred. Application using a roller, a doctor blade, a bar coater, a brush, or the like is also preferred. The application conditions are not particularly limited, and are preferably selected appropriately.

[0095] It is also preferred that the anticorrosive coating composition of the present embodiment is applied to an object to be coated, and then dried and / or baked to form an anticorrosive coating. In this case, the composition may be dried at a relatively low temperature and then baked at a higher temperature.

[0096] The drying and baking method and conditions are not particularly limited, but it is usually preferable to heat the anti-rust coating composition applied to the substrate to 60 to 400°C to remove the solvent and form an anti-rust coating. The lower limit of the heating temperature is more preferably 150°C or higher. The upper limit of the heating temperature is more preferably 350°C or lower. The heating method is not particularly limited, and is preferably any known method such as convection heating, infrared heating, or induction heating. The heat treatment conditions, such as the heating time and heat treatment atmosphere, are also not particularly limited and can be selected appropriately. For example, baking may be performed in air or in an inert gas such as nitrogen gas.

[0097] Before applying the anticorrosive coating composition to an object to be coated, the object may be subjected to degreasing and / or water washing, etc., as necessary. The method for such degreasing and / or water washing is not particularly limited, and can be performed by a known method. Examples of degreasing include solvent degreasing using a hydrocarbon-based degreasing agent. Examples of water washing include water washing using an alkaline aqueous degreasing agent, and cleaning using supercritical water.

[0098] The amount of application of the anticorrosive coating composition of this embodiment is not particularly limited. In general, the average thickness of the anticorrosive coating after drying is preferably 1 to 50 μm. The lower limit of the average thickness is more preferably 5 μm or more. The upper limit of the average thickness is more preferably 30 μm or less. The application amount is 3 to 200 g / m2, in terms of the amount of zinc in the anticorrosive coating after drying. ２ The lower limit is more preferably 20 g / m ２ The upper limit is more preferably 120 g / m ２ The following is the result.

[0099] The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples. Unless otherwise specified, percentages and parts are based on mass. Furthermore, the following experiments were carried out at room temperature and atmospheric pressure unless otherwise specified.

[0100] 1. Production of coated zinc particles

[0101] Example 1

[0102] First, sodium metavanadate (NaVO) was added to a solution prepared by mixing 49.5% by mass of deionized water with 0.8% by mass of a surfactant (manufactured by Kao Corporation, trade name: Emulgen 104P, polyoxyethylene (4) lauryl ether). ３ 3.4% by mass of sodium metavanadate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added and dissolved. Nitric acid at a concentration of 20% by mass was then added to the resulting aqueous solution so that the pH of the solution became 4, yielding an aqueous sodium metavanadate solution. The content of sodium metavanadate in component (C) was 0.56 mol / L in terms of vanadium atoms.

[0103] Next, 43.1% by mass of zinc particles (component (A)) (manufactured by ECKART, product name: STAPA (registered trademark) Zinc 4) having an average particle size of 14.0 μm and 3.2% by mass of dipropylene glycol (DPG, manufactured by Merck) as an organic solvent were mixed to prepare a paste, to which 53.7% by mass of the sodium metavanadate aqueous solution obtained above was added and stirred with a magnetic stirrer for 1 hour. After stirring, the zinc particles were filtered, washed with deionized water until the washings became colorless, and dried in an oven at 100°C to obtain coated zinc particles.

[0104] (Examples 2 and 3)

[0105] Coated zinc particles were obtained in the same manner as in Example 1, except that the pH of the aqueous sodium metavanadate solution was adjusted to pH 2 (Example 2) or pH 6 (Example 3) using nitric acid with a concentration of 20% by mass.

[0106] Example 4

[0107] Coated zinc particles were obtained in the same manner as in Example 1, except that the pH of the aqueous sodium metavanadate solution was adjusted to 10 using sodium carbonate.

[0108] Example 5

[0109] Coated zinc particles were obtained in the same manner as in Example 1, except that the pH of the aqueous sodium metavanadate solution was adjusted to 12 using sodium hydroxide.

[0110] (Examples 6 to 8)

[0111] Coated zinc particles were obtained in the same manner as in Example 1, except that the amounts of component (A), DPG, and component (C) added were changed to the amounts shown in Table 1. The content of sodium metavanadate in component (C) in Example 6 was 0.28 mol / L in terms of vanadium atoms. The content of sodium metavanadate in component (C) in Example 7 was 0.41 mol / L in terms of vanadium atoms. The content of sodium metavanadate in component (C) in Example 8 was 1.13 mol / L in terms of vanadium atoms.

[0112] Example 9

[0113] First, 0.75 g of a surfactant (manufactured by Kao Corporation, product name: Emulgen 104P) was mixed with 48 g of deionized water, and sodium metavanadate (NaVO ３ 7.30 g of nitric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added and stirred overnight to prepare a saturated aqueous solution of sodium metavanadate. The remaining sodium metavanadate was filtered, and then 20% by mass of nitric acid was added to adjust the pH of the aqueous solution to 6, yielding an aqueous solution of sodium metavanadate (note: lowering the pH any further resulted in the formation of a red precipitate). The concentration of the saturated aqueous solution of sodium metavanadate was 1.56 mol / L. That is, the content of sodium metavanadate in component (C) was 1.56 mol / L in terms of vanadium atoms. The concentration of this saturated aqueous solution was determined by the following procedure: First, sodium metavanadate was added to deionized water and stirred overnight. The insoluble matter was filtered off, and then the insoluble matter was washed and dried. The mass of the insoluble matter after drying was measured, and the mass of the insoluble matter was subtracted from the mass of sodium metavanadate added to the deionized water to determine the saturated concentration of sodium metavanadate in the aqueous solution.

[0114] Next, 40.0% by mass of zinc particles (component (A)) (manufactured by ECKART, trade name: STAPA (registered trademark) Zinc 4) and 3.0% by mass of dipropylene glycol (DPG, manufactured by Merck) were mixed to prepare a paste, to which 57.0% by mass of the sodium metavanadate aqueous solution obtained above was added, followed by stirring with a magnetic stirrer for 1 hour. After stirring, the zinc particles were filtered, washed with deionized water until the washings became colorless, and dried in an oven at 100°C to obtain coated zinc particles.

[0115] Examples 10 to 12

[0116] Coated zinc particles were obtained in the same manner as in Example 1, except that the stirring time of the aqueous solution containing zinc particles was changed to 5 minutes (Example 10), 30 minutes (Example 11), and 3 hours (Example 12), respectively.

[0117] Example 13

[0118] Coated zinc particles were obtained in the same manner as in Example 1, except that the amounts of component (A), DPG, and component (C) added were changed to those shown in Table 1. No surfactant was used in Example 13. The content of sodium metavanadate in component (C) was 0.56 mol / L in terms of vanadium atoms.

[0119] Example 14

[0120] Coated zinc particles were obtained in the same manner as in Example 1, except that the step of adjusting the pH of the aqueous sodium metavanadate solution was not performed. The pH of the aqueous sodium metavanadate solution was 8.

[0121] (Examples 15 and 16)

[0122] Coated zinc alloy particles were obtained in the same manner as in Example 1, except that the (A) component was changed to zinc alloy particles containing zinc and tin (manufactured by ECKART, product name: STAPA (registered trademark) 4 ZnSn15 Zinc Paste), and the amounts of the (A), DPG, and (C) components added were changed to the amounts shown in Table 2. STAPA (registered trademark) 4 ZnSn15 Zinc Paste is a mixture of zinc alloy particles and dipropylene glycol (DPG), and the mass ratio of the zinc alloy particles to DPG was approximately 91:9. Furthermore, the mass ratio of zinc atoms to tin atoms in the zinc alloy particles that are STAPA (registered trademark) 4 ZnSn15 Zinc Paste was approximately 85:15. That is, the zinc atom content in these zinc alloy particles was approximately 85% by mass. As a compound containing vanadium, sodium metavanadate (NaVO ３ (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) The content of sodium metavanadate in component (C) of Example 15 was 0.41 mol / L in terms of vanadium atoms. The content of sodium metavanadate in component (C) of Example 16 was 0.28 mol / L in terms of vanadium atoms.

[0123] (Examples 17 and 18)

[0124] Coated zinc alloy particles were obtained in the same manner as in Example 1, except that the (A) component was changed to zinc alloy particles containing zinc and aluminum (manufactured by ECKART, product name: STAPA (registered trademark) 4 ZnAl3 Zinc Paste), and the amounts of the (A), DPG, and (C) components added were changed to those shown in Table 2. STAPA (registered trademark) 4 ZnAl3 Zinc Paste is a mixture of zinc alloy particles and dipropylene glycol (DPG), and the mass ratio of the zinc alloy particles to DPG was approximately 84:16. Furthermore, the mass ratio of zinc atoms to aluminum atoms in the zinc alloy particles that are STAPA (registered trademark) 4 ZnAl3 Zinc Paste was approximately 97:3. That is, the zinc atom content in these zinc alloy particles was approximately 97% by mass. Furthermore, sodium metavanadate (NaVO ) was used as a vanadium-containing compound.３ (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used. The content of sodium metavanadate in component (C) of Example 17 was 0.52 mol / L in terms of vanadium atoms. The content of sodium metavanadate in component (C) of Example 18 was 0.35 mol / L in terms of vanadium atoms.

[0125] Example 19

[0126] Coated zinc particles were obtained in the same manner as in Example 1, except that the sodium metavanadate of component (C) was changed to vanadium (IV) oxysulfate hydrate (manufactured by Tokyo Chemical Industry Co., Ltd.), and the amounts of component (A), DPG, and component (C) added were changed to those shown in Table 2. The content of vanadium oxysulfate in component (C) was 1.50 mol / L in terms of vanadium atoms.

[0127] (Comparative Example 1)

[0128] An experiment was carried out in the same manner as in Example 1, except that the amounts of component (A), DPG, and component (C) added were changed to the amounts shown in Table 1. In Comparative Example 1, sodium metavanadate was not added.

[0129] (Comparative Examples 2 to 6)

[0130] Coated zinc particles were obtained in the same manner as in Example 1, except that the amounts of component (A), DPG, and component (C) added were changed to the amounts shown in Table 1. The amount of sodium metavanadate added was changed to 0.2% by mass (Comparative Example 2), 0.5% by mass (Comparative Example 3), 0.6% by mass (Comparative Example 4), 0.8% by mass (Comparative Example 5), and 1.0% by mass (Comparative Example 6), respectively. The contents of sodium metavanadate in component (C), calculated in terms of vanadium atoms, were 0.03 mol / L (Comparative Example 2), 0.08 mol / L (Comparative Example 3), 0.1 mol / L (Comparative Example 4), 0.13 mol / L (Comparative Example 5), and 0.15 mol / L (Comparative Example 6), respectively.

[0131] (Comparative Example 7)

[0132] Coated zinc alloy particles were obtained in the same manner as in Example 15, except that the amounts of component (A), DPG, and component (C) added were changed to the amounts shown in Table 2. In Comparative Example 7, no vanadium-containing compound was added.

[0133] (Comparative Example 8)

[0134] Coated zinc alloy particles were obtained in the same manner as in Example 17, except that the amounts of component (A), DPG, and component (C) added were changed to the amounts shown in Table 2. In Comparative Example 8, no vanadium-containing compound was added.

[0135] Table 1 shows the production conditions for the coated zinc particles of Examples 1 to 14 and Comparative Examples 1 to 6. Table 2 shows the production conditions for the coated zinc particles of Examples 15 to 19 and Comparative Examples 7 and 8.

[0136]

[0137] 2. Evaluation of coated zinc particles

[0138] (Measurement of hydrogen gas generation amount)

[0139] Five grams of sample coated zinc particles were weighed into a gas collection bottle, and 90 grams of deionized water and 1 gram of surfactant (Kao Corporation, trade name: Emulgen 104P) were added and stirred until uniform. Stirring was then stopped, and the gas collection bottle was immersed in a water bath at 20°C. Hydrogen gas generated by the water displacement method was collected over 24 hours each day on the test start date (Day 1), Day 2, Day 3, Day 4, and Day 5. The amount of hydrogen gas collected each day was then divided by the time spent collecting hydrogen gas to determine the amount of hydrogen gas generated per hour by the coated zinc particles. The amount of hydrogen gas generated per hour on Days 1 through 5 was then summed and multiplied by 24 to determine the cumulative amount of gas generated over the five days. Table 3 shows the measurement results for Examples 1 to 14 and Comparative Examples 1 to 6. Table 4 shows the measurement results for Examples 15 to 19 and Comparative Examples 7 and 8.

[0140] (Evaluation of dispersibility of coated zinc particles in water)

[0141] Five grams of sample coated zinc particles were weighed into a 100 mL plastic container, and 50 grams of deionized water was added. The mixture was stirred for 5 minutes at 500 to 1,000 rpm using a high-speed disperser (manufactured by Primix Corporation, trade name: Homo Disper 2.5). The stirred suspension was then visually inspected for the presence of coated zinc particles that had not dispersed in the deionized water and had formed agglomerates. The results were evaluated as "good" when the coated zinc particles were dispersed in the deionized water, and as "poor" when agglomerates of coated zinc particles were observed in the deionized water. Table 3 shows the evaluation results for Examples 1 to 14 and Comparative Examples 1 to 6. Table 4 shows the evaluation results for Examples 15 to 19 and Comparative Examples 7 and 8.

[0142] (Measurement of the amount of vanadium atoms contained in coated zinc particles)

[0143] Approximately 0.5 g of the coated zinc particles serving as a sample was weighed out, and 10 mL of deionized water and 5 mL of concentrated nitric acid were added thereto and heated to dissolve the coated zinc particles. Subsequently, 1 mL of concentrated hydrochloric acid was added to this solution, and further deionized water was added to make up to 50 mL. This aqueous solution was appropriately diluted according to the vanadium concentration, and the vanadium concentration of the diluted solution was measured using an Agilent ICP mass spectrometer (manufactured by Agilent Technologies, trade name: Agilent 7850 ICP-MS). This allowed the ratio of vanadium atoms (ppm by mass) relative to the total content of zinc particles and the content of vanadium-containing particulate deposits was analyzed. Table 3 shows the measurement results of the vanadium atom ratios for Examples 1 to 14 and Comparative Examples 1 to 6. Table 4 shows the measurement results of the vanadium atom ratios for Examples 15 to 19 and Comparative Examples 7 and 8.

[0144] (Observation of the shape of vanadium-containing particulate deposits and analysis of the average particle size)

[0145] The surfaces of the coated zinc particles used as samples were photographed using a STEM (product name: JEM-ARM200F, spherical aberration corrected scanning electron microscope, manufactured by JEOL Ltd.) at an acceleration voltage of 200 kV and a beam diameter of approximately 0.2 nmΦ, and the cross sections of 10 coated zinc particles were photographed. The photographed cross-sectional images of the coated zinc particles confirmed that a coating was formed by the adhesion of multiple particulate deposits containing vanadium to at least a portion of the surface of the zinc particles. The particle sizes of all the particulate deposits containing vanadium attached to the zinc particles in these cross-sectional images were measured, and the arithmetic mean of these values ​​was taken to analyze the average particle size (nm) of the vanadium particles present on the surfaces of the coated zinc particles. Table 3 shows the analysis results of the average particle sizes of the particulate deposits containing vanadium in Examples 1 to 14 and Comparative Examples 1 to 6. Table 4 shows the analysis results of the average particle sizes of the particulate deposits containing vanadium in Examples 15 to 19 and Comparative Examples 7 and 8.

[0146]

[0147]

[0148] As shown in Tables 3 and 4, it was confirmed that all of the coated zinc particles of Examples 1 to 19 were able to efficiently suppress the amount of hydrogen gas generated when contained in water, and also had good dispersibility in water.

[0149] (Analysis of the components of vanadium-containing particulate deposits)

[0150] The components contained in the vanadium-containing particulate deposits (vanadium particles) on the surface of the coated zinc particles as samples were analyzed using an energy dispersive X-ray spectrometer (EDS) (manufactured by JEOL Ltd., trade name: JED-2300T [100 mm ２ The EDX measurement results were analyzed using an EDS analysis system (manufactured by JEOL Ltd., trade name: Analysis Station).

[0151] Vanadium was also detected from the vanadium particles on the surface of the coated zinc particles of Examples 1 to 19 and Comparative Examples 2 to 6. As an example, Figure 1 shows the EDS spectrum of the vanadium particles on the surface of the coated zinc particles of Example 1. The molybdenum peak in Figure 1 originates from the setup of the measurement device (the grid on which the thin film sample is fixed). Therefore, the molybdenum peak does not originate from the measurement sample.

[0152] (Preparation of Anti-Rust Paint Composition and Evaluation of Anti-Rust Coating)

[0153] 20 g of the coated zinc particles of Example 1, 3.6 g of dipropylene glycol (manufactured by Merck) as a solvent, and 9.0 g of a silane binder (manufactured by Momentive Performance Materials Japan, trade name: SILQUEST A-187 (registered trademark) silane) were added and mixed. Furthermore, using a high-speed disperser (manufactured by Primix Corporation, trade name: Homodisper 2.5 type), the mixture was stirred at 500 to 1000 rpm until a paste with a uniform appearance was obtained. 40 g of deionized water, the pH of which had been adjusted to 4 using phosphoric acid as a pH adjuster, was added to the resulting paste, and the mixture was stirred for an additional 5 minutes. Thereafter, 0.2 g of a thickener (manufactured by Sansho Co., Ltd., trade name: KELZAN AR) was added to this aqueous solution, and the mixture was stirred overnight to obtain an anti-corrosion coating composition.

[0154] The obtained anti-rust coating composition was applied to the entire surface of one side of an iron plate (5 cm x 15 cm) using a bar coater (#14) (manufactured by RD Specialties) to a wet film thickness of approximately 32 μm, dried at 100°C for 10 minutes, and then baked at 350°C for 30 minutes. Another anti-rust coating composition was applied onto this coating using the bar coater (#14), and dried and baked under the same conditions to obtain an anti-rust coating. A rust-preventive coating was also prepared by the same method using the coated zinc particles of Example 1, but at a baking temperature of 220°C.

[0155] In addition, in the same manner as above, anti-rust coatings (baking temperatures: 350°C, 220°C) were produced using the coated zinc particles of Examples 9, 15, and 17, and anti-rust coatings (baking temperatures: 350°C, 220°C) were produced using the coated zinc particles of Comparative Examples 1, 2, 7, and 8, respectively.

[0156] For the obtained anti-rust coatings (baking temperatures: 350°C, 220°C) of the anti-rust paint compositions of Examples 1, 9, 15, and 17, and the anti-rust coatings (baking temperatures: 350°C, 220°C) of the anti-rust paint compositions of Comparative Examples 1, 2, 7, and 8, an X-shaped notch was made in the lower half of each coating with a utility knife. (The upper half of the coating without the notch is referred to as the flat portion, and the lower half with the notch is referred to as the cut portion.) A neutral salt spray test in accordance with JIS Z-2371 was then conducted, and the rust-preventive performance was evaluated by observing the development of red rust. In the neutral salt spray test, first, a salt solution to be used in the neutral salt spray test was prepared. A salt solution was obtained by mixing and dissolving special-grade reagent sodium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and deionized water having an electrical conductivity of 20 μS / cm or less in a polyethylene plastic container at 25°C ± 2°C to a concentration of 50 g / L ± 5 g / L and a pH of 5.0 to 8.0 at 25°C ± 2°C as measured with a pH meter (Horiba, Ltd., Handy pH Meter D-51). The salt solution was then poured into the spray chamber of a neutral salt spray test machine (Suga Test Instruments, STP-90V) at a concentration of 80 cm. ２ The spray was continuously conducted so that the average collection rate of the spray solution per horizontal collection area was 1.5 mL / h ± 0.5 mL / h. A 0.1 mol / L sodium hydroxide solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to the salt solution prepared above so that the pH of the spray solution collected in the spray chamber would be in the range of 6.5 to 7.2 at 25°C ± 2°C, thereby preparing a salt solution for the neutral salt spray test. Next, a neutral salt spray test was conducted. First, an iron plate having a rust-preventive coating of the anticorrosive paint composition was placed in the spray chamber of a testing machine for the neutral salt spray test, with the surface having the rust-preventive coating facing upward, so that the angle between the iron plate and the vertical line was 15°. The temperature in the spray chamber was set to 35°C ± 2°C, and the water temperature in the air saturator of the testing machine for the neutral salt spray test was set to 47°C ± 2°C. The salt solution for the neutral salt spray test was then poured into 80 cm ２ The spray liquid was continuously sprayed onto the rust-preventive coating so that the average collection rate from the horizontal collection area was 1.5 mL / h±0.5 mL / h.

[0157] The coating film was evaluated four days after the start of the neutral salt spray test. Specifically, the amount of red rust generated was visually confirmed and the rust prevention performance was evaluated according to the following criteria: A: Four days after the start of the test, almost no red rust was visually confirmed on either the flat or cut portions of the coating. B: Four days after the start of the test, red rust was visually confirmed on either the cut or flat portions of the coating. C: Four days after the start of the test, red rust was visually confirmed on both the cut and flat portions of the coating.

[0158] The anticorrosive coatings (baking temperatures: 350°C, 220°C) of the anticorrosive paint compositions of Examples 1, 9, 15, and 17 all received an evaluation result of "A" in the salt spray test, confirming at least that they have excellent anticorrosive performance. On the other hand, the anticorrosive coatings (baking temperatures: 350°C, 220°C) of Comparative Examples 1, 2, 7, and 8 all received an evaluation result of "C" in the salt spray test, confirming at least that they have poor anticorrosive performance.

[0159] From the above, it was at least confirmed that the coated zinc particles of this example have excellent stability and dispersibility in aqueous solvents, and that the coating film obtained from them has excellent rust-preventing properties.

[0160] This application claims priority based on Japanese Patent Application No. 2023-198117, filed with the Japan Patent Office on November 22, 2023, the contents of which are incorporated herein by reference.

Claims

1. Coated zinc particles, in which (A) zinc particles and / or zinc alloy particles have at least a portion of their surfaces coated with (B) a particulate deposit containing vanadium, and the ratio of the vanadium atom content to the total content of the (A) component and the (B) component is 7,000 to 25,000 ppm by mass.

2. The coated zinc particles according to claim 1, wherein the average particle size of component (B) is 20 to 100 nm.

3. A method for producing coated zinc particles according to claim 1, comprising the step of contacting at least a portion of the surface of zinc particles and / or zinc alloy particles (A) with an aqueous solution containing at least one compound (C) selected from the group consisting of metavanadate, vanadate, and vanadium oxysulfate, thereby coating at least a portion of the surface of the component (A) with a granular deposit containing vanadium (B).

4. The method for producing coated zinc particles according to claim 3, wherein the content of the compound in the component (C) is 0.28 to 1.6 mol / L in terms of vanadium atoms.

5. The method for producing coated zinc particles according to claim 3 or 4, wherein the pH of the aqueous solution is 2 to 12.

6. An anti-rust paint composition comprising the coated zinc particles according to claim 1 or 2, a binder, and water.

7. The anticorrosive coating composition according to claim 6, further comprising an organic solvent.

8. The rust-preventive coating composition according to claim 6, wherein the binder comprises at least one selected from the group consisting of silane-based binders, titanium-based binders, zirconium-based binders, and organic binder resins.

9. The anti-rust coating composition according to claim 6, wherein the total amount of the solvent in the anti-rust coating composition is 30 to 85 mass %.

10. The anti-rust coating composition according to claim 6, wherein the content of said water in said anti-rust coating composition is 25 to 70 mass %.

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