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

Abstract

Provided is a coated zinc particle, a method for producing a coated zinc particle, and an antirust coating composition, in which at least a part of the surface of (A) a zinc particle and / or a zinc alloy particle is coated with (B) a particulate adherent containing vanadium, and the proportion of the content of vanadium atoms with respect to the total content of the content of the (A) component and the content of the (B) component is 7000 to 25000 mass ppm.

Description

Technical Field

[0001] This invention relates to a zinc-coated particle, a method for manufacturing the zinc-coated particle, and a rust-preventive coating composition. Background Technology

[0002] In recent years, metal rust-preventive coatings used in applications such as coating fasteners for automobiles have incorporated metal powders containing zinc or aluminum as rust-preventive pigments. These coatings offer the advantage of high safety, eliminating concerns about hydrogen embrittlement of the coated object that occurs during the traditional galvanizing process.

[0003] Furthermore, rust-preventive coatings can be categorized into solvent-based coatings containing organic solvents and water-based coatings containing water. However, from the perspective of preventing accidents caused by the ignition of organic solvents, reducing operator exposure, and lowering environmental impact, there is a growing trend towards water-based coatings. Furthermore, even within water-based coatings, there is a trend towards reducing the proportion of organic solvents.

[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 in a water-based coating composition.

[0005] Patent document 2 discloses a method for manufacturing an aqueous coating containing metal powder, wherein the coating contains a substance obtained by hydrolyzing a silane oligomer having both epoxy and alkoxy groups in the presence of a catalyst.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2022-7869.

[0009] Patent Document 2: International Publication No. 2007 / 111769. Summary of the Invention

[0010] The problem the invention aims to solve

[0011] However, the following problem exists: the surface of the metal powder is coated with hydrolyzable resin, and sometimes the hydrolyzable resin peels off the metal surface after a certain period of time.

[0012] Furthermore, in order to prepare a coating containing a substance obtained by hydrolyzing silane oligomers with both epoxy and alkoxy groups in the presence of a catalyst, the following complex operations are required: hydrolyzing the silane using a catalyst, separating the catalyst components after hydrolysis, and continuously removing the alcohols produced as a byproduct of the hydrolysis reaction.

[0013] On the other hand, as mentioned above, from the viewpoint of reducing environmental impact, there is a tendency towards water-based coating compositions, but there is room for improvement. For example, the inventors considered that if zinc and zinc alloys react with water, the amount of hydrogen generated in the water-based coating composition containing zinc and zinc alloy particles during storage may increase. Furthermore, the inventors also considered that increased hydrogen generation may cause the rust-preventive pigments contained in the water-based coating composition containing zinc and zinc alloy particles to deteriorate before application. Further, the inventors considered that the generated hydrogen may increase the internal pressure of the container storing the water-based coating composition containing zinc and zinc alloy particles, thereby increasing safety concerns. Such problems become particularly pronounced in water-based coating compositions with high water content. Based on this consideration, the inventors attempted to develop rust-preventive pigments stable in water-containing solvents.

[0014] The present invention was made in view of the above circumstances, and its object is to provide a coated zinc particle with excellent stability and dispersibility in aqueous solvents, a method for manufacturing the coated zinc particle, and a rust-preventive coating composition.

[0015] Solution to the problem

[0016] To achieve the above-mentioned objectives, the inventors conducted in-depth research and, as a result, obtained insights into coated zinc particles, in which at least a portion of the surface of zinc particles and / or zinc alloy particles is coated with vanadium-containing granular adhering substances, thereby completing the present invention. That is, the present invention is as follows.

[0017] <1> A zinc-coated particle, wherein (A) at least a portion of the surface of the zinc particle and / or zinc alloy particle is coated with (B) a vanadium-containing granular adhering substance, the vanadium atom content being in a ratio of 7000 to 25000 ppm by mass relative to the total content of the (A) component and the (B) component.

[0018] <2> According to the above <1> The coated zinc particles, wherein the average particle size of component (B) is 20-100 nm.

[0019] <3> A method for manufacturing zinc-coated particles, comprising the above-mentioned... <1> or <2> The method for manufacturing the coated zinc particles includes the following steps: by 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 metavanadate, vanadate and vanadium oxysulfate, at least a portion of the surface of the (A) component is coated with (B) a vanadium-containing granular adhering material.

[0020] <4> According to the above <3> In the method for manufacturing the coated zinc particles, the content of the compound in component (C) is 0.28 to 1.6 mol / L, calculated in terms of vanadium atoms.

[0021] <5> According to the above <3> or <4> In the method for manufacturing the coated zinc particles, the pH of the aqueous solution is 2 to 12.

[0022] <6> A rust-preventive coating composition comprising the above-mentioned... <1> or <2> The zinc particles are coated with an adhesive and water.

[0023] <7> According to the above <6> The rust-preventive coating composition further contains an organic solvent.

[0024] <8> According to the above <6> or <7> The rust-preventive coating composition, wherein the adhesive contains at least one selected from silane-based adhesives, titanium-based adhesives, zirconium-based adhesives, and organic adhesive resins.

[0025] <9> According to the above <6> ~ <8> The rust-preventive coating composition described in any one of the following examples, wherein the total content of the solvent in the rust-preventive coating composition is 30-85% by mass.

[0026] <10> According to the above <6> ~ <9> The rust-preventive coating composition according to any one of the following, wherein the water content in the rust-preventive coating composition is 25-70% by mass.

[0027] Invention Effects

[0028] According to the present invention, a zinc-coated particle and a rust-preventive coating composition containing zinc-coated particles with excellent stability and dispersibility in aqueous solvents can be provided. Furthermore, according to the present invention, a simple method for manufacturing zinc-coated particles can be provided. Attached Figure Description

[0029] Figure 1 This is a graph showing the EDS measurement results of the zinc-coated particles in Example 1. Detailed Implementation

[0030] The following is a detailed description of a method for carrying out the present invention (hereinafter referred to as "this embodiment"). This embodiment is merely an example for illustrating the present invention and is not intended to limit the invention to the following content. The present invention can be implemented with appropriate modifications within its scope.

[0031] Furthermore, in this specification, the term “approximately” indicates the meaning of the term after removing the “approximately” within the scope of the technical common sense of those skilled in the art, and also includes the meaning of the term after removing the “approximately”.

[0032] <Coated Zinc Particles>

[0033] The coated zinc particles of this embodiment are particles in which at least a portion of the surface of (A) zinc particles and / or zinc alloy particles is coated with (B) a vanadium-containing granular adhering substance, and the ratio of vanadium atoms to the total content of (A) and (B) components is 7000 to 25000 ppm by mass. By using these coated zinc particles, excellent stability and dispersibility can be imparted when they are contained in water or aqueous solvents. For example, when zinc particles are contained in water or aqueous solvents, problems such as hydrogen generation due to reaction with water or low dispersibility in water may occur. However, it is considered that the coated zinc particles of this embodiment can effectively suppress the generation of hydrogen due to the reaction of zinc particles and / or zinc alloy particles with water, even when contained in water or aqueous solvents, and can exhibit high dispersibility in water. As a result, the anti-rust coating composition containing these coated zinc particles can exhibit good anti-rust performance (but the effects / functions of this embodiment are not limited to these).

[0034] Furthermore, the inventors also considered the fire hazard of zinc particles and / or zinc alloy particles when dispersed in air, or the potential reduction in sacrificial anticorrosion function due to oxidation during storage. Regarding this, for highly reactive zinc particles and / or zinc alloy particles, there are particles whose surface is coated with non-hydrophilic organic substances or mineral oils containing long-chain hydrocarbon groups, such as fatty acids. However, the inventors considered that zinc particles and / or zinc alloy particles coated with such organic substances or mineral oils tend to repel water, thus requiring further improvement to effectively disperse them in aqueous solvents. The coated zinc particles of this embodiment, due to their excellent dispersibility, are also able to meet such improvement requirements.

[0035] The coated zinc particles of this embodiment are (A) zinc particles and / or zinc alloy particles whose surfaces are coated with (B) vanadium-containing granular adhering material. For example, it is preferable to attach vanadium-containing granular adhering material as component (B) to at least a portion of the surface of the zinc particles and / or zinc alloy particles as component (A). Preferably, the coated zinc particles of this embodiment have at least a portion of the surface of component (A) covered by a film formed from vanadium-containing granular adhering material. Furthermore, the coated zinc particles of this embodiment are also preferably coated by attaching a plurality of vanadium-containing granular adhering materials to at least a portion of the surface of component (A) to form a film.

[0036] In this embodiment, the ratio of vanadium atoms to the total content of component (A) and component (B) in the coated zinc particles 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. Furthermore, the upper limit is preferably 24,000 ppm by mass or less, more preferably 21,000 ppm by mass or less. With the vanadium atom ratio within the above range, the vanadium-containing granular adhering material (B) can sufficiently coat the zinc particles (A) and / or zinc alloy particles. Therefore, when the coated zinc particles are added to water or an aqueous solvent, the generation of hydrogen gas caused by the reaction of the coated zinc particles with water can be further effectively suppressed, and the coated zinc particles exhibit further good dispersibility in water.

[0037] The ratio of vanadium atoms to the total content of component (A) and component (B) was obtained by determining the concentration of vanadium atoms in the solution after dissolving the zinc-coated particles in nitric acid using ICP emission spectroscopy and then calculating from that value.

[0038] It should be noted that the vanadium-containing granular adhering material (B) covering the surface of (A) zinc particles and / or zinc alloy particles only needs to cover at least a portion of the surface of the zinc particles. Furthermore, the thickness of the coating layer composed of component (B) may be uneven.

[0039] The components of the zinc-coated particles in this embodiment will now be described.

[0040] (A) Zinc particles and / or zinc alloy particles)

[0041] (A) The composition contains zinc particles and / or zinc alloy particles. Examples of zinc particles and / or zinc alloy particles include: pulverized zinc and / or zinc alloy, fragments, granules, etc. The shape of the particles is not particularly limited, and examples include: approximately spherical, flake, etc., with flakes being more preferred. It may also be noted that two or more zinc particles or zinc alloy particles with different shapes may be used in combination.

[0042] When the zinc particles and / or zinc alloy particles are approximately spherical, although not particularly limited, their average particle size is generally preferably 20 μm or less. 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 using the D50 value of the particle size distribution measured using a laser diffraction particle size distribution apparatus. For example, it can be measured using a laser diffraction / scattering particle size distribution measuring apparatus such as the "Partica LA-960V2" manufactured by Horiba Manufacturing Co., Ltd., or a particle size distribution measuring apparatus such as the "Microtrac (registered trademark) MT3000II" manufactured by MicrotracBEL Co., Ltd.

[0043] When the zinc particles and / or zinc alloy particles are not approximately spherical (e.g., in the case of flakes), their maximum length ("major diameter" in the case of flakes) is not particularly limited, but preferably at least 50% by mass of the particles in component (A) are 1 μm or more and less than 25 μm. Further, preferably at least 90% by mass of the particles in component (A) are less than 50 μm. The aforementioned maximum length ("major diameter" in the case of flakes) can be expressed as the D50 value of the particle size distribution measured using a laser diffraction particle size distribution apparatus. For example, the laser diffraction particle size distribution apparatus can be the apparatus described above.

[0044] Furthermore, when the zinc particles and / or zinc alloy particles are not substantially spherical (e.g., in the case of flakes), 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.

[0045] 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 can be smooth or uneven. For example, the surface of zinc particles and / or zinc alloy particles can also be irregularly shaped. For example, zinc particles and / or zinc alloy particles can also be particles whose surfaces have undergone physical treatments such as surface roughening or rolling, or chemical treatments such as oxidation. By performing such physical or chemical treatments, the physical properties of the particles can be modified. For example, blackening, changing the hue, or imparting a glossy finish can be achieved.

[0046] There is no particular limitation on the zinc atom content in the zinc particles, but high purity is preferred, and more preferably 99% by mass or more.

[0047] The zinc alloy particles are not particularly limited, as long as they are particles of an alloy containing zinc. Examples of metals other than zinc that form the zinc alloy include aluminum, tin, magnesium, nickel, cobalt, and manganese. For example, zinc-aluminum alloys, zinc-tin alloys, and zinc-aluminum-tin alloys are preferred. More preferably, sheets of zinc-aluminum alloys or zinc-tin alloys can be used as the zinc alloy particles in this embodiment.

[0048] The zinc atom content in the zinc alloy particles is not particularly limited, but it is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more. By keeping the zinc atom content in the zinc alloy particles within this range, the rust-proof performance of the rust-proof coating can be further improved.

[0049] 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, further preferably 90% by mass or more, and even more preferably 95% by mass or more. Furthermore, in the 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, further 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 the 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. By having the zinc atom content in the zinc alloy particles within this range, the rust-preventive performance of the rust-preventive coating can be further improved.

[0050] (B) Vanadium-containing granular deposits

[0051] (B) is a vanadium-containing granular adhering substance. The vanadium-containing granular adhering substance is preferably, for example, a vanadium-containing, generally spherical adhering substance present on the surface of zinc particles and / or zinc alloy particles. Furthermore, the vanadium-containing granular adhering substance is also preferably formed into a film by multiple adhering to at least a portion of the surface of component (A). Component (B) covers at least a portion of the surface of component (A) (but the manner in which component (B) is formed in this embodiment is not limited to these).

[0052] In the coated zinc particles, the average particle size of component (B) is preferably 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. Therefore, when the coated zinc particles are added to water or an aqueous solvent, it is expected that hydrogen gas generated due to reaction with water will be less likely to be generated, and that the particles will have better dispersibility in water (but the effects of this embodiment are not limited to these).

[0053] (B) The average particle size of the components is as follows: cross-sections of 10 different coated zinc particles were photographed by STEM-EELS (scanning transmission electron microscopy-electron energy loss spectroscopy). Within these cross-sectional images, the particle size of all vanadium-containing granular attachments on the zinc particles and / or zinc alloy particles was measured and the average value was taken.

[0054] <Manufacturing Method of Coated Zinc Particles>

[0055] As a preferred example of the manufacturing method of the coated zinc particles in this embodiment, a manufacturing method including the following steps can be listed: by 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 metavanadate, vanadate and vanadium oxysulfate, at least a portion of the surface of (A) is coated with (B) a vanadium-containing granular adhering material.

[0056] (C) An aqueous solution containing at least one compound selected from metavanadate, vanadate, and vanadium oxysulfate.

[0057] (C) The composition is an aqueous solution containing at least one compound selected from metavanadate, vanadate, and vanadium oxysulfate. Preferably, the compound used is one or more compounds selected from metavanadate, vanadate, and vanadium oxysulfate, which are water-soluble compounds of vanadium. Among these, metavanadate is more preferred.

[0058] Examples of metavanadates include: ammonium metavanadate, tetra(n-butylammonium) metavanadate, lithium metavanadate, sodium metavanadate, potassium metavanadate, rubidium metavanadate, cesium metavanadate, magnesium metavanadate, calcium metavanadate, strontium metavanadate, and barium metavanadate. Among these, at least one selected from lithium metavanadate, sodium metavanadate, potassium metavanadate, rubidium metavanadate, and cesium metavanadate is preferred, and sodium metavanadate is more preferred.

[0059] Examples of vanadates include: ammonium vanadate, tetra(n-butylammonium) vanadate, lithium vanadate, sodium vanadate, potassium vanadate, rubidium vanadate, cesium vanadate, magnesium vanadate, calcium vanadate, strontium vanadate, and barium vanadate. Among these, at least one selected from lithium vanadate, sodium vanadate, potassium vanadate, rubidium vanadate, and cesium vanadate is preferred, and sodium vanadate is more preferred.

[0060] (Method for manufacturing zinc-coated particles)

[0061] As a preferred example of the method for manufacturing coated zinc particles according to this embodiment, a manufacturing method including the following steps can be listed: At least a portion of the surface of (A) zinc particles and / or zinc alloy particles is contacted with (C) an aqueous solution containing at least one compound selected from metavanadate, vanadate, and vanadium oxysulfate, and at least a portion of the surface of component (A) is coated with (B) a vanadium-containing granular adhering material. To ensure effective contact between component (A) and component (C), stirring or mixing is preferred. Methods for this purpose include, for example, using a magnetic stirrer, stirring blades, a mortar, water flow, airflow, etc. By stirring or mixing, at least a portion of the surface of the zinc particles and / or zinc alloy particles can be coated with a vanadium-containing granular adhering material. Therefore, the method for manufacturing coated zinc particles according to this embodiment is simpler than conventional methods. However, the method of contacting component (A) with component (C) is not limited to this method.

[0062] The contact time between component (A) and 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. Furthermore, the upper limit of the contact time is more preferably 90 minutes or less. With a 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 the vanadium-containing granular adhering material. Therefore, when this coated zinc particle is added to an aqueous solvent, it is expected to effectively suppress the generation of hydrogen gas. In addition, the coated zinc particle exhibits better dispersibility in aqueous solvents.

[0063] When zinc particles and / or zinc alloy particles used as component (A) are coated with a hydrophobic substance, the aqueous solution of component (C) preferably contains a hydrophilic organic solvent, surfactant, etc. By adding the hydrophilic organic solvent, surfactant, etc. to the aqueous solution, component (A) and component (C) can be brought into contact more effectively. However, the method for processing the coating layer of zinc particles and / or zinc alloy particles is not limited to this method.

[0064] The content of the compound in component (C) is preferably 0.28 to 1.6 mol / L, calculated in atomic amounts of vanadium. The lower limit of the compound content is more preferably 0.41 mol / L or higher. The upper limit of the compound content is also preferably the saturation concentration of component (C). For example, when using a saturated aqueous solution of sodium metavanadate as component (C), the content (saturation concentration) of sodium metavanadate in component (C) is, for example, 1.6 mol / L, calculated in atomic amounts of vanadium. Furthermore, when using a saturated aqueous solution of sodium vanadate as component (C), the content (saturation concentration) of sodium vanadate in component (C) is, for example, 1.2 mol / L, calculated in atomic amounts of vanadium. Further, when using a saturated aqueous solution of vanadium oxysulfate as component (C), the content (saturation concentration) of vanadium oxysulfate in component (C) is, for example, 3.3 mol / L, calculated in atomic amounts of vanadium. If a precipitate of a water-soluble vanadium compound is formed by using a saturated aqueous solution of component (C) under the influence of pH adjustment, etc., it is preferable to remove the precipitate by appropriate operations such as filtration. By ensuring that the content of the compound in component (C) is within the above-mentioned range, it is possible to more effectively coat the surface of zinc particles and / or zinc alloy particles with vanadium-containing granular adherings.

[0065] (C) The pH of the aqueous solution in 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 the zinc particles can be appropriately adjusted as long as it does not cause precipitation of the vanadium compound in the aqueous solution. The upper limit of the pH of the aqueous solution in component (C) is more preferably pH 10 or below, further preferably pH 8 or below, even more preferably pH 6 or below, and even more preferably pH 4 or below. With the pH of the aqueous solution within such a range, when the obtained coated zinc particles are contained in water or an aqueous solvent, hydrogen gas generated by the reaction with water is particularly unlikely, and the particles exhibit particularly good dispersibility in the solvent. Furthermore, the anti-rust coating composition containing these coated zinc particles has further improved corrosion resistance.

[0066] pH adjusters used in adjusting the pH of aqueous solutions include, for example: 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; hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, tetramethylammonium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide; carbonates such as lithium carbonate, lithium bicarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, rubidium carbonate, rubidium bicarbonate, cesium carbonate, cesium bicarbonate, magnesium carbonate, magnesium bicarbonate, calcium carbonate, calcium bicarbonate, strontium carbonate, strontium bicarbonate, barium carbonate, and barium bicarbonate; and organic amine compounds such as isopropylamine, triethylamine, tripropylamine, tributylamine, and triethanolamine.

[0067] pH adjusters can be used alone or in combination with two or more.

[0068] In this way, zinc particles and / or zinc alloy particles with a coating formed of vanadium-containing granular adhering material on at least a portion of the surface (preferably the entire surface) can be obtained by coating zinc particles. Further, the coated zinc particles can be obtained, for example, as a composition containing coated zinc particles, a hydrophilic organic solvent, a surfactant, and water. 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, washing with water, and drying for use. Furthermore, for example, the obtained paste or composition containing coated zinc particles can be used directly in an anti-rust coating composition, or the solvent can be removed or newly added as needed, for use in an anti-rust coating composition.

[0069] <Rust-preventive coating composition>

[0070] The rust-preventive coating composition of this embodiment preferably contains coated zinc particles, a binder, and water. Furthermore, the solvent contained in the rust-preventive coating composition may be water only, but it is preferable to also contain an organic solvent. That is, the rust-preventive coating composition of 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.

[0071] The organic solvent contained in the rust-preventive coating composition may also be the organic solvent used in the manufacture of zinc-coated particles. That is, it may also be a paste containing zinc-coated particles obtained by manufacturing zinc-coated particles or a hydrophilic organic solvent contained in the composition.

[0072] The organic solvents that can be used in anti-rust coating compositions are not particularly limited, but examples include: glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol; diol ethers such as monomethyl ether, monoethyl ether, dimethyl ether, and diethyl ether of these glycols; alcohols such as ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, and diacetone alcohol; and ketones such as acetone and methyl ethyl ketone. Among these, glycols and diol ethers are preferred.

[0073] Organic solvents can be used alone or in combination of two or more.

[0074] The total solvent content in the rust-preventive coating composition is preferably 30-85% by mass. The lower limit of this content is more preferably 50% by mass or more. Further, the water content in the rust-preventive coating composition is preferably 25-70% by mass. The lower limit of the water content is more preferably 30% by mass or more, and more preferably 35% by mass or more. Furthermore, the upper limit of the water content is more preferably 65% ​​by mass or less, and more preferably 60% by mass or less. When the solvent contains both 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.

[0075] The rust-preventive coating composition also preferably contains an adhesive. The adhesive is not particularly limited, but for example, it is preferred to contain at least one selected from silane-based adhesives, titanium-based adhesives, zirconium-based adhesives, and organic adhesive resins.

[0076] There are no particular limitations on silane-based adhesives, but examples 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 silane-based adhesives. Examples of silane coupling agents include: vinyl silane coupling agents such as vinyltrimethoxysilane, acrylic silane coupling agents such as methacryloyloxypropyltrimethoxysilane, amino silane coupling agents such as 3-aminopropyltrimethoxysilane, epoxy silane coupling agents such as β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane.

[0077] As a titanium-based adhesive, there are no particular limitations. Examples include: titanium acid, tetraethyl titanate, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, 2-ethylhexyl titanate, tetra-n-butyl titanate, and other polymers, as well as titanium dioxide particles.

[0078] As a zirconium-based adhesive, there are no particular limitations; examples include: zirconium tetrapropoxy, zirconium tributoxystearate, zirconium tributoxymonoacetylacetonate, etc.

[0079] As an organic adhesive resin, there are no particular limitations. Examples include: acrylic resin, epoxy resin, phenolic resin, polystyrene resin, polyurethane resin, oxazoline-containing polymers, polyvinylpyrrolidone, etc.

[0080] The adhesives mentioned above can be used alone or in combination of two or more.

[0081] The content of the binder in the rust-preventive 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. Furthermore, the upper limit of the binder content is more preferably 30% by mass or less, even more preferably 25% by mass or less, and still more preferably 20% by mass or less. By setting the binder content within such a range, the coating film of the rust-preventive coating composition exhibits better adhesion to the coated object, and the sacrificial corrosion protection provided by the zinc particles coated in the rust-preventive coating composition functions more effectively.

[0082] It should be noted that when using silane-based adhesives, the content of the silane-based adhesive in the anti-rust coating composition is not particularly limited, but is generally preferred to be 3 to 20% by mass. The lower limit is more preferably 4% by mass or more, and the upper limit is more preferably 16% by mass or less.

[0083] The rust-preventive coating composition contains coated zinc particles, but may also contain other metal particles.

[0084] The term "other metal particles" (hereinafter sometimes referred to as "other metal particles") is not specifically limited to zinc-coated particles and includes, for example: 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, stainless steel particles, and other metal particles or alloy particles. Other metal particles may be used alone or in combination with two or more.

[0085] The shape of other metal particles is not particularly limited, but they are generally preferred to be approximately spherical or sheet-like, more preferably sheet-like. Furthermore, other metal particles may also be metal particles whose surface is treated, for example, with silica or aliphatic carboxylic acids.

[0086] The total content of coated zinc particles and other metal particles in the anti-rust coating composition is not particularly limited, but is preferably 10 to 50% by mass.

[0087] Rust-preventive coating compositions may also contain, for example, metal oxide pigments or organic pigments.

[0088] As metal oxide pigments, there are no particular limitations, but examples 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, silicon dioxide, titanium oxide, zirconium oxide, silicon oxide aluminum oxide, silicon oxide titanium oxide, silicon oxide magnesium oxide, etc. Their shape is not particularly limited, but particles (particulate form) are preferred.

[0089] As organic pigments, there are no particular limitations. Examples include: β-naphthol pigments, β-hydroxynaphthoic acid pigments, pyrazolone pigments, aryl acetoacetic acid monoazo pigments, aryl acetoacetic acid diazo pigments, benzimidazolone monoazo pigments, isoindolineone pigments, styrene pigments, isoindoline pigments, phthalocyanine pigments, etc.

[0090] Rust-preventive coating compositions 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, thixotropic agents, defoamers, ultraviolet absorbers, flame retardants, corrosion inhibitors, antistatic agents, and colorants, as needed.

[0091] It should be noted that when using water-based coatings with zinc-coated particles, the dispersibility is excellent, and generally, even without the addition of a dispersant, it is expected to achieve a level of performance beneficial to practical use. However, in order to stably disperse other metallic pigments or additives, the use of a dispersant is sometimes preferred. For example, by adding a surfactant to the rust-preventive coating composition, the adhesion or leveling properties of the resulting rust-preventive coating can be improved.

[0092] The surfactant is not particularly limited, but examples include: nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkylamides, polyoxyethylene higher alcohol ethers, polyoxyethylene alkylene alkyl ethers, polyoxyethylene polyoxypropylene glycol, polyethylene glycol fatty acid esters, glycerol fatty acid esters, propylene glycol fatty acid esters, alkyl glycerol ethers, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters; cationic surfactants such as mono-, di-, or trialkylamine salts, alkyl trimethyl ammonium halides, dialkyl dimethyl ammonium halides, and alkyl dimethyl benzyl ammonium chloride; and anionic surfactants such as mono- or dialkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkylphenyl ether phosphates, and dialkyl sulfosuccinates. Nonionic surfactants are preferred as surfactants used in rust-preventive coating compositions. A single surfactant or two or more surfactants can be used. Furthermore, the surfactant contained in the rust-preventive coating composition may also be a surfactant used in the manufacture of zinc-coated particles and thus present in the resulting composition.

[0093] The content of surfactant in the anti-rust coating composition is not particularly limited, but is generally preferred to be 0.01 to 10% by mass.

[0094] To adjust its viscosity, a thickener may be added to the rust-preventive coating composition, for example.

[0095] There are no particular limitations on the type of thickener, but examples include: cellulose-based thickeners such as ethers (cellulose ethers) of methylcellulose, hydroxymethylcellulose, hydroxypropyl methylcellulose, hydroxyethylcellulose, ethyl hydroxyethylcellulose, 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 used in rust-preventive coating compositions. A single thickener or a combination of two or more can be used.

[0096] The content of thickener in the anti-rust coating composition is not particularly limited, but it is generally preferred to be 0.005 to 2% by mass.

[0097] The rust-preventive coating composition preferably contains a repair agent (inhibitor). The repair agent that can be added to the rust-preventive coating composition is a compound that can react with the exposed metal or alloy surface to form a film or modify the surface (repair) when the metal or alloy surface coated with zinc particles or other metal particles in this embodiment is exposed in the composition.

[0098] As a repair agent, there are no particular limitations. Examples include: boron compounds such as boric acid, magnesium oxide, magnesium hydroxide and other magnesium compounds, 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, and silicon compounds such as tetraethoxysilane or silane coupling agents. A single repair agent can be used, or two or more can be used in combination.

[0099] Furthermore, there are no particular limitations on the method of adding the repair agent; for example, it is preferable to add a rust-preventive pigment containing the aforementioned compound. Additionally, it is also preferable to add materials such as those in which the aforementioned compound is infiltrated or supported in zeolite or cellulose nanofibers, or materials in which the aforementioned compound is encapsulated and contained.

[0100] It should be noted that water-soluble compounds containing excess vanadium in the paste or composition obtained from the manufacture of coated zinc particles also function as a repair agent in the rust-preventive coating composition.

[0101] The content of the repair agent in the anti-rust coating composition is not particularly limited and can be appropriately selected, but it is generally preferred to be less than 10% by mass.

[0102] For the purpose of adjusting the coefficient of friction of the rust-preventive coating surface obtained from the rust-preventive coating composition, a lubricant may be added, for example, to the rust-preventive coating composition of this embodiment.

[0103] As a lubricant, there are no particular limitations; examples include: polyolefins and modified polyolefins (polyethylene, modified polyethylene, polypropylene, modified polypropylene, etc.), waxes such as paraffin wax, carnauba wax, fluoropolymers, melamine cyanurate, hexagonal boron nitride, etc. A single lubricant can be used, or two or more can be used in combination.

[0104] The content of lubricant in the anti-rust coating composition is not particularly limited and can be appropriately selected to obtain the desired surface friction coefficient, but it is generally preferred to be less than 20% by mass.

[0105] The rust-preventive coating composition of this embodiment can be manufactured by uniformly stirring / mixing zinc-coated particles or a paste or composition containing zinc-coated particles with coating components such as water and adhesives using a commonly known method.

[0106] (Rust-proof coating and items with rust-proof coating)

[0107] The rust-preventive coating composition of this embodiment is preferably used for rust-preventive coatings and articles having such rust-preventive coatings. Specifically, it is preferable to prepare the rust-preventive coating by drying and / or calcining the rust-preventive coating composition of this embodiment. Furthermore, for example, it is preferable to prepare an article with a rust-preventive coating by applying the rust-preventive coating composition of this embodiment to a coated object, followed by drying and / or calcining.

[0108] The metal or alloy material suitable for use in the rust-preventive coating composition is not particularly limited, but aluminum, aluminum alloys, iron, ferroalloys, carbon steel, alloy steel, and stainless steel are preferred. Furthermore, the substrate to which the rust-preventive coating composition is applied is preferably a substrate that has undergone surface treatments such as plating, chemical conversion treatments (oxidation / nitriding / carburization), or dry plating. More preferably, the substrate contains iron or a ferroalloy, or has a film or layer containing iron or a ferroalloy on its surface. By providing a rust-preventive coating on such a substrate, corrosion resistance is further improved. It should be noted that the object to be coated or the substrate is not particularly limited; it can be a raw material (the metal or alloy material itself), an intermediate product, a final product, etc.

[0109] There are no particular limitations on the method of applying the rust-preventive coating composition to the object to be coated, and any known method can be used. For example, it is preferable to apply the coating by dip coating, dip-rotary coating (dipping with centrifugal removal), spraying, spin coating, etc. In addition, it is also preferable to use rollers, doctor blades, bar coaters, brushes, etc. It should be noted that there are no particular limitations on the coating conditions, and it is preferable to select appropriate ones.

[0110] Furthermore, it is preferable to apply the rust-preventive coating composition of this embodiment to the object and then dry and / or calcine it to form a rust-preventive film. In this case, it is also possible to dry it at a lower temperature and then calcine it at a higher temperature.

[0111] The drying / calcination method and conditions are not particularly limited, but it is generally preferred to heat the anti-rust coating composition applied to the object to 60–400°C to remove the solvent and form an anti-rust film. The lower limit of the heating temperature is more preferably 150°C or higher, and the upper limit is more preferably 350°C or lower. The heating method is not particularly limited, and any known method such as convection heating, infrared heating, or induction heating is preferred. The heat treatment conditions, such as heating time or heat treatment atmosphere, are not particularly limited and can be appropriately selected. For example, calcination can be performed in the atmosphere or in an inert gas such as nitrogen.

[0112] Before applying the anti-rust coating composition to the object, the object may be degreased and / or washed as needed. There are no particular limitations on the method of degreasing and / or washing; known methods can be used. Examples of degreasing include solvent degreasing using hydrocarbon-based degreasing agents. Examples of washing include washing using alkaline aqueous degreasing agents or cleaning using supercritical water.

[0113] The coating amount of the rust-preventive coating composition in this embodiment is not particularly limited. Generally, the average film thickness of the dried rust-preventive coating is preferably 1 to 50 μm. The lower limit of the average film thickness is more preferably 5 μm or more. The upper limit of the average film thickness is more preferably 30 μm or less. Furthermore, the coating amount is preferably 3 to 200 g / m² based on the amount of zinc in the dried rust-preventive coating. 2 The preferred lower limit is 20 g / m³. 2 The above. Its upper limit is more preferably 120g / m³. 2 the following.

[0114] [Example]

[0115] The invention is further illustrated in detail by the following examples and comparative examples, but the invention is not limited to the following examples. It should be noted that, unless otherwise specified, % and parts are based on mass. Furthermore, the following experiments were conducted at room temperature and atmospheric pressure, unless otherwise specified.

[0116] 1. Manufacturing of zinc-coated particles

[0117] (Example 1)

[0118] First, sodium metavanadate (NaVO3, manufactured by Fujifilm and Koko Pure Chemical Industries Co., Ltd.) was dissolved in a solution containing 0.8% by mass of surfactant (manufactured by Kao Corporation, trade name: EMULGEN 104P, polyoxyethylene (4) lauryl ether) in 49.5% by mass of deionized water. Then, nitric acid with a concentration of 20% by mass was added to make the pH of the aqueous solution 4, resulting in an aqueous solution of sodium metavanadate. Note that, based on vanadium atomic conversion, the sodium metavanadate content in component (C) is 0.56 mol / L.

[0119] Next, a paste was prepared by mixing 43.1% by mass of zinc particles with an average particle size of 14.0 μm (component A) (manufactured by ECKART, trade name: STAPA (registered trademark) Zinc 4) and 3.2% by mass of dipropylene glycol (DPG, manufactured by Merck) as an organic solvent. 53.7% by mass of the sodium metavanadate aqueous solution obtained above was then added to the paste, and the mixture was 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.

[0120] (Examples 2 and 3)

[0121] Except that the pH of the sodium metavanadate aqueous solution was adjusted to pH2 (Example 2) and pH6 (Example 3) respectively using 20% ​​by mass nitric acid, zinc-coated particles were obtained in the same manner as in Example 1.

[0122] (Example 4)

[0123] Except that the pH of the sodium metavanadate aqueous solution was adjusted to pH 10 using sodium carbonate, zinc-coated particles were obtained in the same manner as in Example 1.

[0124] (Example 5)

[0125] Except that the pH of the sodium metavanadate aqueous solution was adjusted to pH 12 using sodium hydroxide, zinc-coated particles were obtained in the same manner as in Example 1.

[0126] (Examples 6-8)

[0127] Except for changing the amounts of components (A), DPG, and (C) to those shown in Table 1, coated zinc particles were obtained in the same manner as in Example 1. It should be noted that, in atomic conversions of vanadium, the sodium metavanadate content in component (C) of Example 6 was 0.28 mol / L. In atomic conversions of vanadium, the sodium metavanadate content in component (C) of Example 7 was 0.41 mol / L. In atomic conversions of vanadium, the sodium metavanadate content in component (C) of Example 8 was 1.13 mol / L.

[0128] (Example 9)

[0129] First, 7.30 g of sodium metavanadate (NaVO3, manufactured by Fujifilm and Koko Pure Chemical Industries, Ltd.) was added to a solution containing 0.75 g of surfactant (manufactured by Kao Corporation, trade name: EMULGEN104P) in 48 g of deionized water. The solution was stirred overnight to prepare a saturated aqueous solution of sodium metavanadate. Further, the residual sodium metavanadate was dissolved by filtration, and then 20% by mass nitric acid was added to adjust the pH of the aqueous solution to 6, yielding a sodium metavanadate aqueous solution (note that if the pH is lowered further, a red precipitate is formed). The concentration of the saturated aqueous solution of sodium metavanadate was 1.56 mol / L. That is, in terms of vanadium atomic conversion, the content of sodium metavanadate in component (C) was 1.56 mol / L. The concentration of this saturated aqueous solution was determined by the following steps: First, sodium metavanadate was added to deionized water, stirred overnight, and after filtering out insoluble components, the insoluble components were washed and dried. Weigh the mass of the dried insoluble component, subtract the mass of the insoluble component from the mass of sodium metavanadate added to the deionized water, and thus determine the saturation concentration of sodium metavanadate in the aqueous solution.

[0130] 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) as an organic solvent were mixed to prepare a paste. 57.0% by mass of the sodium metavanadate aqueous solution obtained above was added to the paste, and the mixture was stirred with a magnetic stirrer for 1 hour. After stirring, the zinc particles were filtered, washed with deionized water until the washing solution became colorless, and dried in an oven at 100°C to obtain coated zinc particles.

[0131] (Examples 10-12)

[0132] Except for changing the stirring time of the aqueous solution containing zinc particles to 5 minutes (Example 10), 30 minutes (Example 11), and 3 hours (Example 12), the zinc particles were coated in the same manner as in Example 1.

[0133] (Example 13)

[0134] Except for changing the amounts of components (A), DPG, and (C) to those shown in Table 1, coated zinc particles were obtained in the same manner as in Example 1. No surfactant was used in Example 13. Note that, based on vanadium atomic conversions, the sodium metavanadate content in component (C) is 0.56 mol / L.

[0135] (Example 14)

[0136] Except for the absence of the step of adjusting the pH of the sodium metavanadate aqueous solution, zinc-coated particles were obtained in the same manner as in Example 1. It should be noted that the pH of the sodium metavanadate aqueous solution was 8.

[0137] (Examples 15 and 16)

[0138] Except for changing component (A) to zinc alloy particles containing zinc and tin (manufactured by ECKART Corporation, trade name: STAPA (registered trademark) 4 ZnSn15 Zinc Paste) and changing the amount of each component (A), DPG, and (C) to the amounts shown in Table 2, coated zinc alloy particles were obtained in the same manner as in Example 1. It should be noted that STAPA (registered trademark) 4 ZnSn15 Zinc Paste is a mixture of zinc alloy particles and dipropylene glycol (DPG), with a mass ratio of zinc alloy particles to DPG of approximately 91:9. Furthermore, the mass ratio of zinc atoms to tin atoms in the zinc alloy particles of STAPA (registered trademark) 4 ZnSn15 Zinc Paste is approximately 85:15. That is, the zinc atom content in these zinc alloy particles is approximately 85% by mass. It should be noted that sodium metavanadate (NaVO3, manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.) was used as the vanadium-containing compound. Based on vanadium atomic conversions, the sodium metavanadate content in component (C) of Example 15 is 0.41 mol / L. Based on vanadium atomic conversions, the sodium metavanadate content in component (C) of Example 16 is 0.28 mol / L.

[0139] (Examples 17 and 18)

[0140] Except for changing component (A) to zinc alloy particles containing zinc and aluminum (manufactured by ECKART Corporation, trade name: STAPA (registered trademark) 4 ZnAl3 Zinc Paste) and changing the amount of each component (A), DPG, and (C) to the amounts shown in Table 2, coated zinc alloy particles were obtained in the same manner as in Example 1. It should be noted that STAPA (registered trademark) 4 ZnAl3 Zinc Paste is a mixture of zinc alloy particles and dipropylene glycol (DPG), with a mass ratio of zinc alloy particles to DPG of approximately 84:16. Furthermore, the mass ratio of zinc atoms to aluminum atoms in the zinc alloy particles of STAPA (registered trademark) 4 ZnAl3 Zinc Paste is approximately 97:3. That is, the zinc atom content in these zinc alloy particles is approximately 97% by mass. It should be noted that sodium metavanadate (NaVO3, manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.) was used as the vanadium-containing compound. Based on vanadium atomic conversions, the sodium metavanadate content in component (C) of Example 17 is 0.52 mol / L. Based on vanadium atomic conversions, the sodium metavanadate content in component (C) of Example 18 is 0.35 mol / L.

[0141] (Example 19)

[0142] Except for replacing sodium metavanadate in component (C) with vanadium oxysulfate (IV) hydrate (manufactured by Tokyo Chemical Industry Co., Ltd.) and changing the amounts of components (A), DPG, and (C) to those shown in Table 2, coated zinc particles were obtained in the same manner as in Example 1. It should be noted that, based on vanadium atomic conversion, the content of vanadium oxysulfate in component (C) is 1.50 mol / L.

[0143] (Comparative Example 1)

[0144] Except that the amounts of components (A), DPG, and (C) were changed to those shown in Table 1, the procedure was carried out in the same manner as in Example 1. It should be noted that sodium metavanadate was not added in Comparative Example 1.

[0145] (Comparative Examples 2-6)

[0146] Except for changing the amounts of components (A), DPG, and (C) as shown in Table 1, coated zinc particles were obtained in the same manner as in Example 1. It should be noted that 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. It should be noted that, based on vanadium atomic conversion, the sodium metavanadate content in component (C) was 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.

[0147] (Comparative Example 7)

[0148] Except that the amounts of components (A), DPG, and (C) were changed to those shown in Table 2, coated zinc alloy particles were obtained in the same manner as in Example 15. It should be noted that no vanadium-containing compounds were added in Comparative Example 7.

[0149] (Comparative Example 8)

[0150] Except that the amounts of components (A), DPG, and (C) were changed to those shown in Table 2, coated zinc alloy particles were obtained in the same manner as in Example 17. It should be noted that no vanadium-containing compounds were added in Comparative Example 8.

[0151] Table 1 shows the manufacturing conditions for the coated zinc particles of Examples 1-14 and Comparative Examples 1-6. Table 2 shows the manufacturing conditions for the coated zinc particles of Examples 15-19 and Comparative Examples 7-8.

[0152] [Table 1]

[0153]

[0154] [Table 2]

[0155]

[0156] 2. Evaluation of Zinc-Coated Particles

[0157] (Determination of hydrogen production)

[0158] Weigh 5g of coated zinc particles (as sample) into a gas collection bottle, add 90g of deionized water and 1g of surfactant (manufactured by Kao Corporation, trade name: EMULGEN 104P), and stir until homogeneous. Then, stop stirring and immerse the gas collection bottle in a water bath at 20°C. On the first day of the experiment (Day 1), Day 2, Day 3, Day 4, and Day 5, collect the generated hydrogen gas for 24 hours each day using the water displacement method. Further, divide the amount of hydrogen gas collected each day by the time of hydrogen collection to determine the amount of hydrogen gas produced per hour by the coated zinc particles. In addition, sum the hourly hydrogen gas production from Day 1 to Day 5, and multiply this sum by 24 to obtain the cumulative gas production over 5 days. Table 3 shows the measurement results for Examples 1-14 and Comparative Examples 1-6. Table 4 shows the measurement results for Examples 15-19 and Comparative Examples 7-8.

[0159] (Evaluation of the dispersibility of zinc-coated particles in water)

[0160] Weigh 5g of coated zinc particles (as sample) into a 100mL plastic container, add 50g of deionized water, and stir for 5 minutes at 500-1000rpm using a high-speed disperser (PRIMIX, trade name: Homodisper 2.5). Then, visually inspect the suspension for any undispersed coated zinc particles that have formed aggregates in the deionized water. A "good" rating is given when the coated zinc particles are dispersed in the deionized water, and a "poor" rating is given when aggregates of coated zinc particles are observed in the deionized water. Table 3 shows the evaluation results for Examples 1-14 and Comparative Examples 1-6. Table 4 shows the evaluation results for Examples 15-19 and Comparative Examples 7-8.

[0161] (Determination of the amount of vanadium atoms contained in zinc-coated particles)

[0162] Approximately 0.5 g of coated zinc particles, to be used as a sample, was weighed, and 10 mL of deionized water and 5 mL of concentrated nitric acid were added. The mixture was then heated to dissolve the coated zinc particles. Next, 1 mL of concentrated hydrochloric acid was added to the solution, followed by deionized water, and the volume was adjusted to 50 mL. The aqueous solution was appropriately diluted according to the vanadium concentration, and the vanadium concentration of the diluted solution was determined using an Agilent ICP mass analyzer (manufactured by Agilent Technologies, trade name: Agilent 7850 ICP-MS). The ratio (mass ppm) of vanadium atoms relative to the zinc particles and the total content of vanadium-containing particulate matter was analyzed. Table 3 shows the determination results of the vanadium atom ratio for Examples 1-14 and Comparative Examples 1-6. Table 4 shows the determination results of the vanadium atom ratio for Examples 15-19 and Comparative Examples 7-8.

[0163] (Observation of the shape and analysis of the average particle size of vanadium-containing granular deposits)

[0164] The surface of the zinc-coated particles used as samples was imaged using a STEM (JEOL Ltd., trade name: JEM-ARM200F, aberration-corrected scanning electron microscope) with an accelerating voltage of 200 kV and a beam diameter of approximately 0.2 nmΦ. Cross-sectional images of 10 zinc-coated particles were captured. In the captured cross-sectional images of the zinc-coated particles, it was confirmed that a coating was formed by the attachment of multiple vanadium-containing granular deposits to at least a portion of the surface of the zinc particles. Within these cross-sectional images, the particle size of all vanadium-containing granular deposits attached to the zinc particles was measured, and the arithmetic mean of these values ​​was taken to analyze the average particle size (nm) of vanadium particles present on the surface of the zinc-coated particles. Table 3 shows the analysis results of the average particle size of the vanadium-containing granular deposits in Examples 1-14 and Comparative Examples 1-6. Table 4 shows the analysis results of the average particle size of the vanadium-containing granular deposits in Examples 15-19 and Comparative Examples 7-8.

[0165] [Table 3]

[0166]

[0167] [Table 4]

[0168]

[0169] As shown in Tables 3 and 4, it was confirmed that the coated zinc particles of Examples 1 to 19 could effectively suppress the amount of hydrogen produced when in water, and also had good dispersibility in water.

[0170] (Analysis of the components contained in vanadium-containing granular deposits)

[0171] The zinc-coated particles used as samples were analyzed using an energy-dispersive X-ray spectroscopy (EDS) apparatus (manufactured by JEOL Ltd., product name: JED-2300T [100mm]). 2 A silicon drift detector (SDD) was used to analyze the composition of vanadium-containing granular deposits (vanadium particles) coating the surface of zinc particles. Furthermore, the results of the EDX measurements were analyzed using an EDS analysis system (manufactured by JEOL Ltd., trade name: AnalysisStation).

[0172] Vanadium was also detected in the zinc-coated particles from Examples 1-19 and Comparative Examples 2-6. As an example, Figure 1 The EDS spectrum of vanadium particles coated on the surface of zinc particles in Example 1 is shown. Figure 1The molybdenum peak originates from the setup of the measuring apparatus (the grid that fixes the thin film sample). Therefore, the molybdenum peak does not originate from the measured sample.

[0173] (Preparation of anti-rust coating composition and evaluation of anti-rust coating)

[0174] Add and mix 20g of the zinc-coated particles from Example 1, 3.6g of dipropylene glycol (manufactured by Merck) as a solvent, and 9.0g of a silane-based binder (manufactured by Momentive Performance Materials Japan, trade name: SILQUEST A-187 silane). Further, using a high-speed disperser (manufactured by PRIMIX, trade name: Homodisper 2.5), stir at 500-1000 rpm until a homogeneous paste is formed. Add 40g of deionized water (pH adjusted to 4 using phosphoric acid as a pH adjuster) to the resulting paste and stir further for 5 minutes. Then, add 0.2g of a thickener (manufactured by Sanshoku Corporation, trade name: KELZAN AR) to this aqueous solution and stir overnight to obtain the anti-rust coating composition.

[0175] Using a bar coater (#14) (manufactured by RD Specialties), the obtained rust-preventive coating composition was applied to the entire single side of an iron plate (5cm × 15cm) to a wet film thickness of approximately 32μm. It was dried at 100°C for 10 minutes, followed by calcination at 350°C for 30 minutes. The rust-preventive coating composition was then applied again to this film using the bar coater (#14), and dried and calcined under the same conditions to obtain a rust-preventive coating. Using the same method, a rust-preventive coating was also prepared at a calcination temperature of 220°C using the coated zinc particles from Example 1.

[0176] In addition, using the same method as described above, anti-rust films using zinc-coated particles from Examples 9, 15 and 17 (calcination temperatures: 350°C and 220°C) and anti-rust films using zinc-coated particles from Comparative Examples 1, 2, 7 and 8 (calcination temperatures: 350°C and 220°C) were prepared respectively.

[0177] The rust-preventive coatings (calcination temperatures: 350°C and 220°C) of the rust-preventive coating compositions obtained in Examples 1, 9, 15, and 17, and the rust-preventive coatings (calcination temperatures: 350°C and 220°C) of Comparative Examples 1, 2, 7, and 8, were respectively made with an X-shaped cut on the lower half of the coating using a cutting tool (the upper half of the coating without cuts is called the flat part, and the lower half with cuts is called the cut part). Furthermore, a neutral salt spray test according to JIS Z-2371 was conducted to observe the formation of red rust, thereby evaluating the rust-preventive performance. In the neutral salt spray test, firstly, the salt solution used in the neutral salt spray test was prepared. In a polyethylene plastic container, at 25°C ± 2°C, a solution of super-grade sodium chloride (manufactured by Fujifilm and Kojun Chemical Co., Ltd.) and deionized water with a conductivity of less than 20 μS / cm was mixed and dissolved 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 by a pH meter (Horiba Manufacturing Co., Ltd., handheld pH meter D-51). Further, in the spray chamber of a neutral salt spray tester (SUGA Tester Co., Ltd., STP-90V), the solution was sprayed at an 80 cm⁻¹ spray rate. 2 The salt solution was continuously sprayed at an average collection rate of 1.5 mL / h ± 0.5 mL / h over a horizontal collection area. A 0.1 mol / L sodium hydroxide solution (manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.) was added to the prepared salt solution to bring the pH of the spray collected in the spray chamber to a range of pH 6.5–7.2 at 25°C ± 2°C, thus preparing a neutral salt spray test solution. Next, a neutral salt spray test was conducted. First, an iron plate with a rust-preventive coating composition was placed in the spray chamber of the neutral salt spray tester with the rust-preventive coating surface facing upwards and the vertical line forming an angle of 15° with the iron plate. The temperature inside the spray chamber was set to 35°C ± 2°C, and the water temperature in the air saturator of the neutral salt spray tester was set to 47°C ± 2°C. The spray was then sprayed at an angle of 80 cm... 2 A neutral salt solution for spraying tests was continuously sprayed onto the anti-rust coating at an average collection rate of 1.5 mL / h ± 0.5 mL / h across a horizontal collection area.

[0178] The coating was evaluated 4 days after the start of the neutral salt spray test. Specifically, the amount of red rust formation was visually confirmed, and the rust-preventive performance was evaluated according to the following criteria.

[0179] A: Four days after the start of the test, almost no red rust was visually detected on either the flat or cut part of the film.

[0180] B: Four days after the start of the test, red rust was visually confirmed on one of the cut or flat parts of the film.

[0181] C: Four days after the start of the test, red rust was visually confirmed on either the cut or flat surface of the film.

[0182] The rust-preventive coatings of Examples 1, 9, 15, and 17 (calcination temperatures: 350°C and 220°C) received an "A" rating in the salt spray test, confirming excellent rust-preventive performance. Conversely, the rust-preventive coatings of Comparative Examples 1, 2, 7, and 8 (calcination temperatures: 350°C and 220°C) received a "C" rating in the salt spray test, confirming low rust-preventive performance.

[0183] As shown above, it has been confirmed that the coated zinc particles of this embodiment have excellent stability and dispersibility in aqueous solvents, and the resulting coating film has excellent anti-rust properties.

[0184] 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. A zinc-coated particle, characterized in that, In the coated zinc particles (A) At least a portion of the surface of zinc particles and / or zinc alloy particles is coated with (B) vanadium-containing granular deposits. The ratio of the vanadium atom content to the total content of component (A) and component (B) 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 20–100 nm.

3. A method for manufacturing coated zinc particles, which is the method for manufacturing coated zinc particles as described in claim 1, characterized in that, The process includes the following steps: At least a portion of the surface of component (A) is coated with vanadium-containing granular adhering material by 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 metavanadate, vanadate and vanadium oxysulfate.

4. The method for manufacturing coated zinc particles according to claim 3, wherein, Based on the atomic conversion of vanadium, the content of the compound in component (C) is 0.28 to 1.6 mol / L.

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

6. A rust-preventive coating composition, characterized in that, The rust-preventive coating composition contains the coated zinc particles as described in claim 1 or 2, as well as a binder and water.

7. The anti-rust coating composition according to claim 6, wherein, It also contains organic solvents.

8. The anti-rust coating composition according to claim 6, wherein, The adhesive contains at least one selected from silane-based adhesives, titanium-based adhesives, zirconium-based adhesives, and organic adhesive resins.

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

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

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