Film-forming method

Abstract

To provide a film-forming method in which a coating film having excellent weather resistance can be formed.SOLUTION: Provided is a film-forming method of forming a coating layer after forming an anticorrosive ground layer on a metal base, where the anticorrosive ground layer contains resin component and zinc powder, and is formed by coating an anticorrosive ground material containing zinc powder in heating residue by 70 mass% or more, the anticorrosive ground material contains flat extender pigment, and the average particle diameter of the flat extender pigment is larger than the average particle diameter of the zinc powder.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel method for forming a coating. [Background technology]

[0002] As the anticorrosion base for heavy-duty anticorrosion coatings, anticorrosion base materials containing a large amount of zinc powder, such as zinc-rich paints, are mainly used. Known zinc-rich paints include organic zinc-rich paints that use organic resins as binder components and inorganic zinc-rich paints that use inorganic resins as binder components. Organic zinc-rich paints have superior adhesion to substrates such as iron compared to inorganic zinc-rich paints. However, coatings formed by organic zinc-rich paints may have poor weather resistance when exposed to the elements for long periods of time.

[0003] In contrast, Patent Document 1 describes a corrosion-resistant coating method in which a specific primer layer, intermediate layer, and top coat layer are laminated on a coating film (zinc-rich coating film) formed from a zinc-rich paint, with the aim of improving weather resistance. As in Patent Document 1, it is possible to improve weather resistance by laminating various coating film layers on the zinc-rich coating film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-314596 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, in order for a zinc-rich coating film to exhibit effective corrosion protection against a substrate such as iron, a continuous electrical short circuit between the zinc powder and the substrate is necessary, and since damage such as cracking in the coating film may result in a decrease in corrosion protection, it is important to improve the weather resistance of the zinc-rich coating film even when various coating film layers are laminated on top of the zinc-rich coating film. In particular, organic zinc-rich paints are more likely to experience such a decrease in corrosion protection than inorganic zinc-rich paints, and there is room for improvement in improving the weather resistance of organic zinc-rich coating films.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to provide a film forming method that can form a coating film having excellent weather resistance. [Means for solving the problem]

[0007] In order to solve these problems, the inventors conducted extensive research and came up with the idea of a coating formation method that uses a corrosion-resistant primer containing zinc dust and a specific flat pigment, thereby completing the present invention.

[0008] That is, the present invention has the following features. 1. A coating forming method for forming a coating layer on a metal substrate after forming a corrosion-resistant base layer, The corrosion-resistant base layer is formed by applying a corrosion-resistant base material containing a resin component and zinc powder, the zinc powder content of which in the heating residue is 70% by mass or more, The corrosion-resistant primer contains a flat extender pigment, A method for forming a coating, characterized in that the average particle size of the flat extender pigment is larger than the average particle size of the zinc dust. 2. The method for forming a coating according to 1., wherein the content of the flake extender pigment relative to the zinc powder is 0.1 to 10% by mass. [Effects of the Invention]

[0009] According to the coating film forming method of the present invention, the weather resistance of the formed coating film can be improved and corrosion prevention can be maintained for a long period of time. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described.

[0011] [Metal base material] The coating target in the coating formation method of the present invention is a structure requiring corrosion protection, such as a building or civil engineering structure, and specific examples include roads, bridges, railways, ports, buildings, factories, prefabricated houses, power plants, steel towers, amusement parks, swimming pools, and other amusement and recreational facilities. Examples of metal substrates include iron, cold-rolled steel, aluminum steel, stainless steel, copper steel, hot-dip galvanized steel, hot-dip zinc-aluminum alloy-plated steel, electrogalvanized steel, electroalloy-plated steel, alloy-plated steel, copper-plated steel, tin-plated steel, and the like, as well as metal substrates obtained by subjecting these metal substrates to a surface treatment such as a phosphate-based or chromate-based treatment. If these metal substrates have various existing coatings (e.g., alkyd resin, chlorinated rubber, acrylic resin, urethane resin, acrylic silicone resin, fluororesin, etc.), it is desirable to remove these existing coatings by scraping, etc. It is also desirable to remove rust from the metal substrate.

[0012] [Corrosion-resistant base layer] The anticorrosion base layer of the present invention is a layer formed by applying an anticorrosion base material containing a resin component and zinc dust. The resin component is not particularly limited, and various resins can be used. The resin component may be in the form of an aqueous resin (e.g., a water-soluble resin, a water-dispersible resin (resin emulsion)), a solvent-based resin (e.g., a solvent-soluble resin, a non-water-dispersible resin, etc.), or a solventless resin. Examples of resin types include vinyl acetate resin, polyester resin, alkyd resin, vinyl chloride resin, epoxy resin, acrylic resin, urethane resin, acrylic silicone resin, fluororesin, etc., or composite resins thereof. Among these, one or more resins selected from acrylic resin, epoxy resin, urethane resin, etc. are preferred. In the present invention, it is preferable to use an epoxy resin as the resin component, and it is particularly preferable to include an epoxy resin and an amine curing agent as the resin component.

[0013] Epoxy resins having two or more epoxy groups per molecule can be used, including bisphenol-type epoxy resins such as bisphenol A epoxy resins and bisphenol F epoxy resins; phenol novolac-type epoxy resins such as phenol novolac-type bisphenol A epoxy resins and phenol novolac-type bisphenol F epoxy resins; novolac-type epoxy resins such as cresol novolac-type epoxy resins and bisphenol A novolac-type epoxy resins; alicyclic epoxy resins; hydrogenated bisphenol A epoxy resins; glycidyl ether-type epoxy resins; bisphenol S-type epoxy resins; biphenyl-type epoxy resins; dicyclo-type epoxy resins; and naphthalene-type epoxy resins. These can be used alone or in combination. Among these, bisphenol-type epoxy resins such as bisphenol A epoxy resins and bisphenol F epoxy resins are preferred.

[0014] In the present invention, modified products of the above epoxy resins (hereinafter also referred to as "modified epoxy resins") can also be used. Examples of such modified epoxy resins include aliphatic modified epoxy resins, butadiene-based epoxy resins, ε-caprolactone-modified epoxy resins, thiol-based epoxy resins, amine-modified epoxy resins, rubber-modified epoxy resins, urethane-modified epoxy resins, polyol-modified epoxy resins, and fatty acid-modified epoxy resins. These can be used alone or in combination of two or more. Among these, fatty acid-modified epoxy resins are preferred.

[0015] Fatty acid-modified epoxy resins are obtained by subjecting an aliphatic polybasic acid compound to an epoxy resin by addition reaction. The addition reaction can be, for example, an esterification reaction. Examples of the aliphatic polybasic acid compounds used here include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, cyclohexanedicarboxylic acid, succinic acid, malonic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, 1,12-docanoic acid, and dimer acid. Among these, dimer acid is preferred.

[0016] Dimer acids are dimers of unsaturated fatty acids. Examples of unsaturated fatty acids that constitute dimer acids include oleic acid, elaidic acid, cetoleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, soybean oil fatty acids, tall oil fatty acids, and linseed oil fatty acids.

[0017] The epoxy resin used in the present invention has an epoxy equivalent (based on the solid content) of preferably 300 to 3000 g / eq, more preferably 400 to 2000 g / eq, even more preferably 450 to 1500 g / eq, and particularly preferably 500 to 1300 g / eq. In the present invention, "α to β" is synonymous with "α or more and β or less."

[0018] Examples of amine curing agents include polyamine compounds such as aliphatic polyamines, alicyclic polyamines, aromatic polyamines, heterocyclic polyamines, aliphatic polyamides, alicyclic polyamides, aromatic polyamides, aliphatic polyamidoamines, alicyclic polyamidoamines, and aromatic polyamidoamines. These can be used alone or in combination of two or more. In the present invention, among these, one or more aliphatic amine curing agents selected from aliphatic polyamines, aliphatic polyamides, and aliphatic polyamidoamines can be preferably used.

[0019] In the present invention, modified products of the above polyamine compounds (modified amine compounds) are preferred. Examples of such modified amine compounds include those obtained by reacting the above aliphatic polyamines with compounds obtained from phenols and formaldehyde (Mannich-modified products), adduct-modified products obtained by preliminarily reacting a portion of the amino groups in the aliphatic polyamines with epoxy compounds, and cyanoethylated products obtained by reacting the above aliphatic polyamines with acrylonitrile. These can be used alone or in combination. Among these, adduct-modified products and Mannich-modified products are preferred, as they further enhance the curability and weather resistance of the formed coating film and can provide long-term corrosion protection. In the present invention, Mannich-modified epoxy adduct amines are particularly preferred.

[0020] The amine curing agent used in the present invention preferably has an active hydrogen equivalent (per solid content) of 40 to 300 g / eq, more preferably 50 to 250 g / eq, and even more preferably 60 to 200 g / eq. By having the active hydrogen equivalent within the above range, sufficient effects can be obtained in terms of adhesion, etc. The active hydrogen equivalent is the value obtained by dividing the molecular weight of the amine curing agent by the number of hydrogen atoms in the amino group.

[0021] The compounding ratio of the epoxy resin to the amine curing agent, [(amount of amine curing agent / active hydrogen equivalent of amine curing agent) / (amount of epoxy resin / epoxy equivalent of epoxy resin)], is preferably 0.3 to 2.0, more preferably 0.5 to 1.8, and even more preferably 0.6 to 1.5. The amount and active hydrogen equivalent of the amine curing agent, and the amount and epoxy equivalent of the epoxy resin are all based on the solid content. When the compounding ratio of the epoxy resin to the amine curing agent satisfies the above range, the composition is excellent in curability, is suitable in terms of adhesion to substrates, and exhibits better weather resistance and corrosion resistance.

[0022] The content of the resin component in the heating residue of the coating material is preferably 3 to 35 mass %, more preferably 5 to 30 mass %, as resin solid content. Note that the "heating residue" in the present invention is a value measured by the method of JIS K5601-1-2, and the heating temperature is 105°C and the heating time is 60 minutes. The content of the resin component is preferably 2 to 30 mass %, more preferably 3 to 25 mass %, in terms of resin solid content, based on the total amount (100 mass %) of the coating material.

[0023] The corrosion-resistant base of the present invention is a zinc-rich paint containing zinc powder in an amount of 70 mass % or more, preferably 70 to 90 mass %, based on the heating residue of the corrosion-resistant base. The content of zinc powder is preferably 60 to 90 mass %, more preferably 65 to 90 mass %, based on the total amount (100 mass %) of the corrosion-resistant base.

[0024] The zinc powder is not particularly limited as long as it is one that is used in ordinary zinc-rich paints. The average particle size of the zinc dust is preferably 1 to 15 μm, more preferably 1.5 to 12 μm, and even more preferably 2 to 10 μm. When the average particle size of the zinc dust satisfies the above range, better corrosion resistance and weather resistance can be exhibited. Furthermore, the zinc dust is preferably made of particles with a nearly spherical shape. In this case, the effects of the present invention are more easily achieved. The average particle size of the zinc dust is a value measured using a laser diffraction particle size distribution analyzer.

[0025] The corrosion-protective primer of the present invention is characterized in that, in addition to the resin component and the zinc dust, it further contains a flaky extender pigment, the average particle size of which is larger than that of the zinc dust. In this case, the weather resistance, particularly crack resistance, of the corrosion-protective primer layer formed by the corrosion-protective primer can be improved. The mechanism of action is presumably, but not limited to, that the average particle size of the flaky extender pigment is larger than that of the zinc dust, so that the flaky extender pigment is randomly present among the zinc dust particles, resulting in the formation of a corrosion-protective primer layer with elasticity or flexibility, which can suppress cracking of the corrosion-protective primer layer and provide excellent weather resistance. Furthermore, the presence of the flaky extender pigment can prevent oxygen and moisture from penetrating into the corrosion-protective primer layer, and the flaky extender pigment is less likely to inhibit electrical short-circuiting between the zinc dust and the substrate, thereby achieving sufficient corrosion protection.

[0026] The average particle size of the flaky extender pigment may be selected to be larger than the average particle size of the zinc dust used, but is preferably 2 to 40 μm, more preferably 3 to 30 μm, and even more preferably 7 to 20 μm. More specifically, it is preferably about 1.2 to 5 times the average particle size of the zinc dust, and even more preferably about 1.5 to 3 times. When this range is satisfied, excellent weather resistance and corrosion resistance can be exhibited. On the other hand, if the average particle size of the flaky extender pigment is smaller than the average particle size of the zinc dust, the coating film becomes prone to cracking, which is undesirable.

[0027] The flat extender pigment in the present invention is an extender pigment having an aspect ratio [average particle diameter / thickness] of preferably 2 to 100 (more preferably 3 to 80). The average particle size of the flat extender pigment is a value measured using a laser diffraction particle size distribution analyzer, and the thickness is the average value of 50 thicknesses measured using a scanning electron microscope.

[0028] The specific gravity of the flaky body pigment is preferably smaller than that of zinc powder. Furthermore, the Mohs hardness of the flaky body pigment is preferably 5 or less, more preferably 3 or less, and even more preferably 2.5 or less. In this case, it is advantageous in terms of manifesting the effects of the present invention.

[0029] Examples of such flat extender pigments include talc, mica, and glass flakes. In the present invention, it is preferable to include talc as the flat extender pigment, which can further enhance the above-mentioned effects.

[0030] The mixing ratio of the flaky extender pigment to the zinc powder is preferably 0.1 to 10 mass %, more preferably 0.3 to 8 mass %, and even more preferably 0.5 to 5 mass %, which can further enhance the above-mentioned effects. The content of the flake extender pigment in the heating residue of the anticorrosion primer is 0.1 to 10 mass%, more preferably 0.2 to 8 mass%. Furthermore, the content of the flake extender pigment in the total amount of the anticorrosion primer (100 mass%) is preferably 0.05 to 10 mass%, more preferably 0.1 to 10 mass%, and even more preferably 0.2 to 8 mass%. In such cases, the above-mentioned effects can be further enhanced.

[0031] In addition to the components described above, the anticorrosion base of the present invention can also contain various other components to the extent that they do not affect the effects of the present invention. Examples of such components include color pigments, extender pigments, solvents, plasticizers, preservatives, antifungal agents, antialgae agents, rust inhibitors, antifoaming agents, leveling agents, pigment wetting and dispersing agents, thickeners, viscosity adjusters, anti-settling agents, anti-sagging agents, anti-skinning agents, dehydrating agents, matting agents, UV absorbers, light stabilizers, antioxidants, catalysts, curing accelerators, and silane coupling agents.

[0032] The anticorrosion base material of the present invention preferably contains a curing accelerator. Suitable curing accelerators include tertiary or quaternary amine compounds, such as quaternary ammonium salts (e.g., tetramethylammonium bromide, tetrabutylammonium bromide, etc.); diazabicyclo compounds (e.g., DBU (1,8-diazabicyclo[5.4.0]undecene-7), DBN (1,5-diazabicyclo[4.3.0]nonene-5), DBU-phenol salt, DBU-octylate salt, DBU-p-toluenesulfonate, DBU-formate, and DBU-phenol novolac resin salt); tertiary amines (e.g., benzyldimethylamine, 2-(dimethylaminomethyl)phenol, and 2,4,6-tris(dimethylaminomethyl)phenol (TAP)) and their salts; and dimethylurea compounds (e.g., aromatic dimethylurea, aliphatic dimethylurea, etc.). These compounds can be used alone or in combination. The content of the curing accelerator is preferably 0.01 to 5 mass %, more preferably 0.05 to 3 mass %, based on the total amount (100 mass %) of the anticorrosion base material.

[0033] The anticorrosion base material of the present invention preferably contains a silane coupling agent. This improves the adhesion of the anticorrosion base layer, further enhancing the effects of the present invention. Furthermore, by using the silane coupling agent in combination with the above-mentioned flat body pigment, the silane coupling agent acts on the surface of the flat body pigment, thereby further enhancing the effects of the present invention.

[0034] Examples of silane coupling agents include vinyl group-containing silane coupling agents, epoxy group-containing silane coupling agents, amino group-containing silane coupling agents, methacryl group-containing silane coupling agents, chloropropyl group-containing silane coupling agents, and mercapto group-containing silane coupling agents. These can be used alone or in combination of two or more. In the present invention, epoxy group-containing silane coupling agents are particularly preferred.

[0035] Examples of epoxy group-containing silane coupling agents include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyldimethylmethoxysilane, γ-glycidoxypropyl(ethyl)dimethoxysilane, β-3,4-epoxycyclohexylethyltrimethoxysilane, β-3,4-epoxycyclohexylethyltriethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 8-glycidoxyoctylmethyldimethoxysilane, and 8-glycidoxyoctylmethyldiethoxysilane.

[0036] The content of the silane coupling agent is preferably 0.05 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total amount (100% by mass) of the anticorrosive primer. The mixing ratio of the silane coupling agent to the flat extender pigment is preferably 1 to 60% by mass, more preferably 5 to 50% by mass. In this case, the above-mentioned effects can be further enhanced.

[0037] The corrosion-resistant base material of the present invention preferably contains a thickener. Examples of thickeners include organic bentonite, finely divided silica, surface-treated calcium carbonate, amide wax, hydrogenated castor oil wax, benzylidene sorbitol, metal soap, polyethylene oxide, polymerized vegetable oil, and polycarboxylic acid amine salts. These can be used alone or in combination. In the present invention, it is preferable to contain one or more selected from organic bentonite, amide wax, and polyethylene oxide.

[0038] The content of the thickener is preferably 0.05 to 15 mass %, more preferably 0.1 to 10 mass %, of the total amount of the coating material (00 mass %). In such a case, the dispersion stability of the zinc powder is improved and sufficient viscosity can be imparted, which is advantageous for coating workability, such as thick coating. As a result, a uniform anticorrosion base layer can be formed, and even better anticorrosion properties and corrosion resistance can be exhibited.

[0039] The anticorrosion primer of the present invention preferably contains a pigment wetting / dispersing agent. The pigment wetting / dispersing agent preferably contains a pigment wetting / dispersing agent having an acid value. The acid value of such a pigment wetting / dispersing agent is preferably 10 to 200 mgKOH / g, more preferably 30 to 150 mgKOH / g. Furthermore, the pigment wetting / dispersing agent preferably has an amine value of 100 mgKOH / g or less, more preferably 0 to 30 mgKOH / g. In such cases, the wetting effect on zinc dust is enhanced, allowing for uniform dispersion of the zinc dust and stabilizing the paint viscosity. As a result, coating workability is improved, a uniform anticorrosion primer layer can be formed, and excellent anticorrosion properties and corrosion resistance can be achieved. The content of the pigment wetting / dispersing agent is preferably 0.01 to 5 mass%, more preferably 0.05 to 3 mass%, based on the total amount (100 mass%) of the anticorrosion primer.

[0040] The anticorrosion base material of the present invention is preferably a multi-component type (e.g., two-component, three-component, etc.) having a base agent containing an epoxy resin and an amine curing agent. That is, during distribution, the base agent and the curing agent are stored in separate packages, and they are mixed at the time of use (application). The zinc powder and the flaky extender pigment may be mixed with at least one of the base agent and the curing agent, or may be added when the base agent and the curing agent are mixed. In the present invention, it is preferable to mix them with the base agent. Furthermore, various additives may be mixed into at least one of the base agent and the curing agent depending on various purposes.

[0041] When applying (painting) the anticorrosive base material of the present invention to a metal substrate, an application tool such as a spray, roller, or brush can be used. The amount of application when painting is preferably 30 to 500 g / m 2 , more preferably 50 to 300 g / m 2 The thickness (dry film thickness) of the anticorrosion base layer is preferably 30 to 100 μm. The number of times of application may be set appropriately, but is preferably 1 to 2 times.

[0042] (covering layer) In the coating formation method of the present invention, various coating materials (e.g., primer, intermediate, top coat, etc.) are further applied on top of the corrosion-resistant base layer formed by the above-mentioned corrosion-resistant base material to form a coating layer (primer layer, intermediate layer, top coat layer, etc.), thereby forming a corrosion-resistant coating film structure. Examples of such coating materials include those containing a resin component and various pigments (one or more selected from color pigments, extender pigments, and anti-rust pigments). Such coating materials are suitable in terms of improving corrosion resistance, weather resistance, and the like, and imparting aesthetic appeal through various colors.

[0043] Various resins can be used as the resin component in the above coating materials (undercoat material, intermediate coating material, topcoat material). Examples of resin types include vinyl acetate resin, polyester resin, alkyd resin, vinyl chloride resin, epoxy resin, acrylic resin, urethane resin, acrylic silicone resin, fluororesin, etc., or composite resins thereof. Among these, one or more selected from epoxy resin, acrylic resin, urethane resin, acrylic silicone resin, fluororesin, etc. are preferred. In addition, these resin components may have crosslinking reactivity. When a resin component having crosslinking reactivity is used, the durability, water resistance, weather resistance, chemical resistance, adhesion, etc. of the coating can be improved.

[0044] Examples of the form of the resin component include water-soluble resins, water-dispersible resins (resin emulsions), solvent-soluble resins, solventless resins, non-aqueous dispersion resins, and powdered resins. Among these, one or more resins selected from the group consisting of water-soluble resins, water-dispersible resins, solvent-soluble resins, and non-aqueous dispersion resins are preferred.

[0045] As the pigment, known color pigments, extender pigments, and anti-corrosion pigments can be used. Among these, examples of color pigments include inorganic color pigments such as titanium oxide, zinc oxide, carbon black, lamp black, bone black, graphite, black iron oxide, cobalt black, copper chromium black, copper manganese iron black, ferric oxide (red iron oxide), molybdate orange, yellow iron oxide, titanium yellow, ultramarine, Prussian blue, cobalt blue, cobalt green, iron chromium composite oxide, manganese bismuth composite oxide, manganese yttrium composite oxide, and manganese iron cobalt composite oxide; organic color pigments such as azo, naphthol, pyrazolone, anthraquinone, perylene, quinacridone, disazo, isoindolinone, benzimidazole, phthalocyanine, and quinophthalone; and functional pigments such as pearl pigments, fluorescent pigments, phosphorescent pigments, and metallic pigments. By using one or more of these color pigments, any hue can be obtained.

[0046] Examples of extender pigments include heavy calcium carbonate, light calcium carbonate, kaolin, clay, china clay, diatomaceous earth, hydrous finely powdered silicic acid, barite powder, barium sulfate, precipitated barium sulfate, barium carbonate, magnesium carbonate, silica powder, and aluminum hydroxide, and one or more of these can be used.

[0047] Examples of anti-rust pigments include phosphate compounds such as zinc phosphate, iron phosphate, aluminum phosphate, calcium phosphate, and magnesium phosphate; phosphate compounds such as zinc phosphite, iron phosphite, aluminum phosphite, calcium phosphite, and magnesium phosphite; polyphosphate compounds such as zinc polyphosphate, iron polyphosphate, and aluminum polyphosphate; molybdic acid compounds such as zinc molybdate, aluminum molybdate, calcium molybdate, barium molybdate, and aluminum phosphomolybdate; vanadium compounds such as vanadium oxide; boric acid compounds such as barium borate, barium metaborate, and calcium borate; and cyanamide compounds such as zinc cyanamide and zinc calcium cyanamide. One or more of these can be used. The anti-rust pigment preferably has an average particle size of 10 μm or less (more preferably 0.05 μm to 5 μm, and even more preferably 0.1 μm to 3 μm).

[0048] Such coating materials may contain various components other than the above-mentioned components, as long as the effects of the present invention are not significantly impaired. Such components include, for example, thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreeze agents, pH adjusters, preservatives, antifungal agents, anti-algae agents, antibacterial agents, dispersants, antifoaming agents, adsorbents, fibers, crosslinking agents, UV absorbers, antioxidants, anti-pollution agents, water repellents, catalysts, solvents, water, etc. In addition, coating materials can be produced by uniformly mixing the above-mentioned resin components, pigments, and, if necessary, the above-mentioned various components, using conventional methods.

[0049] Specifically, as the resin component of the primer, epoxy resin is suitable. Also, as the epoxy resin, it is preferable to include a fatty acid-modified epoxy resin, more preferably a dimer acid-modified epoxy resin. These may be one-component or multi-component (two-component, etc.), but it is preferable to be a two-component resin containing a curing agent component. Also, as the form of the resin component, solvent-soluble resin, non-aqueous dispersion resin, etc. are suitable. Furthermore, it is preferable that the primer contains the above-mentioned rust-preventive pigment. As the resin component of the intermediate coating material, urethane resin, acrylic silicone resin, etc. are suitable. These may be one-component or multi-component (two-component, etc.), but two-component resins containing a curing agent are preferred. Furthermore, the form of the resin component is preferably a solvent-soluble resin, a non-aqueous dispersion resin, etc. As the topcoat material, acrylic silicone resin and fluororesin are suitable as the resin component. These may be one-component or multi-component (two-component, etc.), but two-component resins containing a hardener component are preferred. In addition, the form of the resin component is preferably a solvent-soluble resin, a non-aqueous dispersion resin, etc.

[0050] A known application tool can be used to apply each coating material. Examples of application tools that can be used include a spray, roller, and brush. The amount of each coating material to be applied can be determined appropriately depending on the coating material, but is preferably 50 to 600 g / m. 2 , more preferably 80 to 500 g / m 2 When applying, the coating material can be diluted as needed. The coating material is preferably applied once or twice.

[0051] (Anti-corrosion coating structure) As an embodiment of the corrosion-resistant coating film structure formed by the coating film forming method of the present invention, for example, An embodiment having a corrosion-resistant base layer and a top coat layer, An embodiment having a corrosion-resistant base layer, a primer layer, and a top coat layer; An embodiment having a corrosion-resistant base layer, a primer layer, an intermediate coat layer, and a top coat layer; In the present invention, an embodiment having a corrosion-resistant base layer, a primer layer, an intermediate coat layer, and a top coat layer is preferred. In such a case, it is preferred in terms of improving corrosion resistance, weather resistance, etc., and imparting aesthetic appeal through various colors. [Example]

[0052] Examples and comparative examples will be given below to clarify the features of the present invention.

[0053] <Corrosion prevention base material> The base agent and curing agent were prepared according to the formulations shown in Tables 1 and 2, and then mixed to produce anticorrosion primers 1 to 19 (zinc-rich paints 1 to 19). The raw materials used are shown below. Epoxy resin 1: Dimer acid-modified bisphenol A epoxy resin solution, solid content 60% by mass, epoxy equivalent (solid content) 750 g / eq Epoxy resin 2: Bisphenol A type epoxy resin solution, solid content 60% by mass, epoxy equivalent (solid content) 840 g / eq Amine curing agent 1: Modified polyamine, solid content 70% by mass, active hydrogen equivalent (solid content) 125g / eq Amine curing agent 2: Mannich-modified epoxy adduct amine, solid content 100% by mass, active hydrogen equivalent (solid content) 85g / eq Zinc powder 1: Granular zinc powder (average particle size 5 μm, specific gravity 7.1) Zinc powder 2: Granular zinc powder (average particle size 8 μm, specific gravity 7.1) Flat extender pigment 1: Talc (average particle size 10 μm, specific gravity 2.7, Mohs hardness 1) Flat extender pigment 2: Talc (average particle size 15 μm, specific gravity 2.7, Mohs hardness 1) Flat extender pigment 3: Talc (average particle size 3 μm, specific gravity 2.7, Mohs hardness 1) Pigment wetting and dispersing agent: copolymer with acidic groups (acid value 101 mg KOH / g) Silane coupling agent: γ-glycidoxypropyltriethoxysilane Curing accelerator: 2,4,6-tris(dimethylaminomethyl)phenol (others) Additive 1: Thickeners (amide wax, organic bentonite, polyethylene oxide), defoamers, etc. Additive 2: Thickeners (amide wax, organic bentonite), defoamers, etc. Solvents: aromatic hydrocarbon solvents, alcohol solvents, etc.

[0054] <Undercoat material 1> The primer material was prepared by mixing 25 parts by mass of an amine curing agent {aliphatic polyamidoamine, solids content 70% by weight, active hydrogen equivalent (solids content) 180 g / eq} with a base agent containing 200 parts by mass of epoxy resin {dimer acid-modified bisphenol A-type solid epoxy resin solution, solids content 60% by weight, epoxy equivalent (solids content) 750 g / eq}, 100 parts by mass of titanium oxide, 75 parts by mass of heavy calcium carbonate, 50 parts by mass of talc, 3.5 parts by mass of polyphosphate-based rust preventive pigment, solvent, and additives (thickener, dispersant, defoamer, etc.). <Intermediate coating material 1> The base material was made by mixing 200 parts by mass of soluble acrylic polyol (hydroxyl value 50 KOH mg / g, solid content 50 mass%, mineral spirit solution), 125 parts by mass of titanium oxide, and 100 parts by mass of precipitated barium sulfate with polyisocyanate (NCO content 21 mass%) so that the NCO / OH ratio relative to the hydroxyl groups of the acrylic polyol was 1.0, to create the intermediate coating material. <Top coating material 1> The topcoat material was prepared by mixing a base material containing 160 parts by mass of fluorine-containing polyol (hydroxyl value 35 KOHmg / g, fluorine content 20% by mass, solid content 50% by mass), 40 parts by mass of acrylic polyol (hydroxyl value 35 KOHmg / g, acid value 3 KOHmg / g, solid content 50% by mass), 85 parts by mass of titanium oxide, solvent, and additives (thickener, dispersant, defoamer, etc.) with polyisocyanate (NCO content 21% by mass) so that the NCO / OH ratio relative to the total hydroxyl groups of the fluorine-containing polyol and acrylic polyol was 1.0.

[0055] (Examples 1 to 21, Comparative Examples 1 to 4) 300g / m of anti-corrosion base material (zinc-rich paint) was applied to grid-blasted steel plate SS400 (300mm x 150mm x 3.2mm). 2 After drying at 23°C for 24 hours, the sides and back of the test piece were further coated with the same paint and dried at 23°C for 6 days to form a corrosion-resistant base layer. Next, coating layers (primer layer, intermediate layer, and top coat layer) were formed on the anticorrosion base layer as shown in Table 2. The primer layer is applied to the anticorrosion base layer at a coating weight of 250g / m 2After drying for 24 hours at 23°C, apply the primer again at a rate of 250g / m 2 The coating was sprayed onto the surface so that the coating was as follows: and then dried at 23°C for 24 hours. The intermediate coating layer is applied to the underlayer (anticorrosion base layer or primer layer) at a rate of 150 g / m 2 The coating was sprayed onto the surface so that the coating was as follows: and then dried at 23°C for 24 hours. The top coat layer is applied to the undercoat (anticorrosion base layer, primer layer, or intermediate coat layer) at a rate of 150 g / m 2 The coating was sprayed onto the surface so that the coating was uniform, and then dried at 23°C for 24 hours. The test specimens thus prepared were evaluated as follows. The results are shown in Table 3.

[0056] <Weather resistance (outdoor exposure weather resistance test)> The test specimens were exposed outdoors (for two years) in Ibaraki City, Osaka Prefecture, facing south and tilted at a 45-degree angle, and the occurrence of abnormalities (rust, swelling, cracking, and peeling) was confirmed. The evaluation criteria were a five-point scale (aa>a>b>c>d), with "aa" indicating no abnormalities and "d" indicating obvious abnormalities. <Corrosion resistance (salt spray test)> The prepared specimens were subjected to a neutral salt spray resistance test in accordance with JIS K5600-7-1:1999, and the occurrence of abnormalities (rust, swelling, cracks, and peeling) was confirmed. The evaluation criteria were a five-point scale (aa>a>b>c>d), with "aa" indicating no abnormalities and "d" indicating obvious abnormalities.

[0057] [Table 1]

[0058] [Table 2]

[0059] [Table 3]

Claims

1. A coating forming method for forming a coating layer on a metal substrate after forming a corrosion-resistant base layer, comprising: The corrosion-resistant base layer is formed by applying a corrosion-resistant base material containing a resin component and zinc powder, the zinc powder content of which in the heating residue is 70% by mass or more, The corrosion-resistant primer contains a flat extender pigment, A coating forming method characterized in that the average particle size of the flat extender pigment is larger than the average particle size of the zinc dust.

2. 2. The method for forming a coating film according to claim 1, wherein the content of said flake extender pigment relative to said zinc dust is 0.1 to 10% by mass.

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