Coating material

Abstract

To provide a coating material which enables formation of a coating film excellent in weather resistance.SOLUTION: A coating material contains a resin component and zinc powder, wherein the coating material contains a flat extender pigment, and an average particle diameter of the flat extender pigment is larger than an average particle diameter of the zinc powder.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a novel coating material.

Background Art

[0002] As an anticorrosive base for heavy anticorrosive coatings, mainly coating materials containing a large amount of zinc powder, such as zinc-rich paints, are used. As zinc-rich paints, organic zinc-rich paints having an organic resin as a binder component and inorganic zinc-rich paints having an inorganic resin as a binder component are known. Organic zinc-rich paints are superior to inorganic zinc-rich paints in terms of adhesion to substrates such as iron. However, the coating films formed by organic zinc-rich paints may be inferior in weather resistance to long-term exposure.

[0003] On the other hand, Patent Document 1 describes an anticorrosive coating in which a specific undercoat layer, intermediate coat layer, and topcoat layer are laminated on a coating film (zinc-rich coating film) layer formed by a zinc-rich paint for the purpose of improving weather resistance. As described in Patent Document 1 above, it is possible to enhance weather resistance by laminating various coating film layers on a zinc-rich coating film.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems 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. If damage such as cracks occurs in the coating film, the corrosion protection may decrease. Therefore, it is also important to improve the weather resistance of the zinc-rich coating film. In particular, organic zinc-rich paints are more likely to cause such a decrease in corrosion protection compared to inorganic zinc-rich paints, and there was room for improvement in enhancing the weather resistance of organic zinc-rich coating films.

[0006] The present invention has been made in view of such points, and an object thereof is to provide a coating material capable of forming a coating film excellent in weather resistance.

Means for Solving the Problems

[0007] In order to solve such problems, as a result of intensive studies, the inventors of the present invention came up with the idea of blending a specific flat pigment into a coating material containing zinc powder, and completed the present invention.

[0008] That is, the present invention has the following features. 1. A coating material containing a resin component and zinc powder, and containing 70% by mass or more of zinc powder in the heat residue, the above coating material contains a flat extender pigment, A coating material characterized in that the average particle diameter of the above flat extender pigment is larger than the average particle diameter of the above zinc powder. 2. The coating material according to 1, wherein the content of the flat extender pigment with respect to the zinc powder is 0.1 to 10% by mass.

Effects of the Invention

[0009] According to the coating material of the present invention, the weather resistance of the formed coating film can be enhanced, and corrosion protection can be exhibited over a long period of time.

Modes for Carrying Out the Invention

[0010] Hereinafter, modes for carrying out the present invention will be described.

[0011] The present invention relates to a coating material containing a resin component and zinc powder. The resin component is not particularly limited, and various resins can be used. As for the form of the resin component, it may be any of an aqueous resin (for example, a water-soluble resin, a water-dispersible resin (resin emulsion)), a solvent-based resin (for example, a solvent-soluble resin, a non-aqueous dispersion resin, etc.), and a solvent-free resin. Examples of the type of resin include vinyl acetate resin, polyester resin, alkyd resin, vinyl chloride resin, epoxy resin, acrylic resin, urethane resin, acrylic silicone resin, fluororesin, or composite resins thereof. Among these, one or more selected from acrylic resin, epoxy resin, urethane resin, etc. are preferable. In the present invention, it is preferable to use an epoxy resin as the resin component, and particularly, it is suitable to contain an epoxy resin and an amine curing agent as the resin component.

[0012] As the epoxy resin, those having two or more epoxy groups in one molecule can be used. For example, bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, phenol novolak type bisphenol A epoxy resin, phenol novolak type bisphenol F epoxy resin and other phenol novolak type epoxy resins, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin and other novolak type epoxy resins, alicyclic epoxy resin, hydrogenated bisphenol A type epoxy resin, glycidyl ether type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, dicyclo type epoxy resin, naphthalene type epoxy resin, etc. can be mentioned. These can be used alone or in combination of two or more. Among these, bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin are preferable.

[0013] In the present invention, a modified product of the above epoxy resin (hereinafter, also referred to as "modified epoxy resin") 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, fatty acid modified epoxy resins, and the like. These can be used alone or in combination of two or more. Among these, fatty acid modified epoxy resins are preferred.

[0014] The fatty acid modified epoxy resin is obtained by subjecting an aliphatic polybasic acid compound to an addition reaction with an epoxy resin. For the addition reaction, for example, an esterification reaction or the like can be used. Examples of the aliphatic polybasic acid compound used herein 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-dodecanedioic acid, dimer acid, and the like. Among these, dimer acid is preferred.

[0015] Dimer acid is a dimer of unsaturated fatty acids. Examples of the unsaturated fatty acids constituting the dimer acid include oleic acid, elaidic acid, cetoleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, soybean oil fatty acid, tall oil fatty acid, linseed oil fatty acid, and the like.

[0016] The epoxy resin used in the present invention preferably has an epoxy equivalent (per solid content) of 300 to 3000 g / eq, more preferably 400 to 2000 g / eq, still 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".

[0017] Examples of the amine curing agent include polyamine compounds such as aliphatic polyamines, alicyclic polyamines, aromatic polyamines, heterocyclic polyamines, aliphatic polyamides, alicyclic polyamides, aromatic polyamides, aliphatic polyamide amines, alicyclic polyamide amines, and aromatic polyamide amines. 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 polyamide amines can be preferably used.

[0018] In the present invention, modified products (modified amine compounds) of the above polyamine compounds are preferred. Examples of such modified amine compounds include those obtained by reacting the above aliphatic polyamine with a compound obtained from phenols and formaldehyde (Mannich-modified product), adduct-modified products obtained by previously reacting a part of the amino groups in the aliphatic polyamine with an epoxy compound, and cyanoethylated products obtained by reacting the aliphatic polyamine with acrylonitrile. These can be used alone or in combination of two or more. Among these, adduct-modified products and Mannich-modified products are preferred, and they can further enhance the curability and weather resistance of the formed coating film and exhibit corrosion resistance over a long period. In the present invention, in particular, Mannich-modified epoxy adduct amine is preferred.

[0019] 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 still more preferably 60 to 200 g / eq. By the active hydrogen equivalent being within the above range, sufficient effects can be obtained in terms of adhesion and the like. The active hydrogen equivalent is a value obtained by dividing the molecular weight of the amine curing agent by the number of hydrogen atoms of the amino group.

[0020] The mixing ratio of the epoxy resin and the amine curing agent is preferably 0.3 to 2.0, more preferably 0.5 to 1.8, and even more preferably 0.6 to 1.5, where [(the amount of amine curing agent / the active hydrogen equivalent of the amine curing agent) / (the amount of epoxy resin / the epoxy equivalent of the epoxy resin)]. Note that the amount of the amine curing agent and its active hydrogen equivalent, as well as the amount of the epoxy resin and its epoxy equivalent, are all based on the solid content. When the mixing ratio of the epoxy resin and the amine curing agent satisfies the above range, it has excellent curability, is suitable in terms of adhesion to the substrate, etc., and can exhibit more excellent weather resistance and corrosion resistance.

[0021] The content of the resin component is preferably 3 to 35% by mass, more preferably 5 to 30% by mass as the resin solid content in the heat residue of the coating material. Note that the "heat residue" in the present invention is a value measured by the method of JIS K5601-1-2, the heating temperature is 105 °C, and the heating time is 60 minutes. Also, the content of the resin component is preferably 2 to 30% by mass, more preferably 3 to 25% by mass as the resin solid content in the total amount (100% by mass) of the coating material.

[0022] The coating material of the present invention contains 70% by mass or more, preferably 70 to 90% by mass of zinc dust in the heat residue of the coating material, and is a zinc-rich paint. Note that the content of zinc dust is preferably 60 to 90% by mass, more preferably 65 to 90% by mass in the total amount (100% by mass) of the coating material.

[0023] The zinc dust is not particularly limited as long as it is used in ordinary zinc-rich paints and can be used. The average particle diameter 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 diameter of the zinc dust satisfies the above range, more excellent corrosion resistance and weather resistance can be exhibited. Also, the zinc dust preferably has particles that are substantially spherical. In this case, the effects of the present invention are easily obtained. Note that the average particle diameter of the zinc dust is a value measured by a laser diffraction particle size distribution analyzer.

[0024] In addition to the above resin component and zinc powder, the coating material of the present invention further contains a flat extender pigment, and is characterized in that the average particle diameter of the flat extender pigment is larger than the average particle diameter of the zinc powder. In such a case, the weather resistance, particularly the crack resistance, of the coating film (hereinafter, also simply referred to as "coating film") formed by the coating material can be enhanced. The mechanism of action is not limited to the following, but since the average particle diameter of the flat extender pigment is larger than the average particle diameter of the zinc powder, the flat extender pigment randomly exists between the zinc powders, so that a coating film layer with elasticity or flexibility is formed, and cracks and the like in the coating film can be suppressed, and it is presumed that excellent weather resistance can be exhibited. Further, due to the presence of the flat extender pigment, the intrusion of oxygen and moisture into the coating film can be suppressed, and since the flat extender pigment has little possibility of inhibiting the electrical short circuit between the zinc powder and the substrate, a sufficient effect can also be obtained in terms of corrosion protection.

[0025] The average particle diameter of the flat extender pigment may be selected to be larger than the average particle diameter of the zinc powder used according to the average particle diameter of the zinc powder used. Preferably, it is 2 to 40 μm, more preferably 3 to 30 μm, and still more preferably 7 to 20 μm. More specifically, about 1.2 to 5 times, and further preferably about 1.5 to 3 times the average particle diameter of the zinc powder is suitable. When such a range is satisfied, excellent weather resistance and corrosion protection can be exhibited. On the other hand, when the average particle diameter of the flat extender pigment is smaller than the average particle diameter of the zinc powder, the coating film is likely to crack, which is not preferable.

[0026] In addition, the flat extender pigment in the present invention is an extender pigment having an aspect ratio [average particle diameter / thickness] preferably of 2 to 100 (more preferably 3 to 80). In addition, the average particle diameter of the flat extender pigment is a value measured by a laser diffraction particle size distribution measuring device. Further, the thickness refers to the average value of these thicknesses when the thicknesses of 50 are measured with a scanning electron microscope.

[0027] Further, the flat extender pigment preferably has a specific gravity smaller than that of zinc dust. Furthermore, the Mohs hardness of the flat extender pigment is preferably 5 or less, more preferably 3 or less, and even more preferably 2.5 or less, which is suitable in terms of the manifestation of the effects of the present invention.

[0028] Examples of such flat extender pigments include talc, mica, glass flakes, etc. In the present invention, it is preferable to contain talc as the flat extender pigment. Thereby, the above effects can be further enhanced.

[0029] The mixing ratio of the flat extender pigment is preferably 0.1 to 10% by mass, more preferably 0.3 to 8% by mass, and even more preferably 0.5 to 5% by mass with respect to the above zinc dust. In such a case, the above effects can be further enhanced. Also, the content of the flat extender pigment is 0.1 to 10% by mass, more preferably 0.2 to 8% by mass, in the heat residue of the coating material. Furthermore, in the total amount of the coating material (100% by mass), it is preferably 0.05 to 10% by mass, more preferably 0.1 to 10% by mass, and even more preferably 0.2 to 8% by mass. In such a case, the above effects can be further enhanced.

[0030] In addition to the above components, various components can be mixed into the coating material of the present invention to such an extent that they do not affect the effects of the present invention. Examples of such components include coloring pigments, extender pigments, solvents, plasticizers, preservatives, fungicides, algicides, rust preventives, defoamers, leveling agents, pigment wetting and dispersing agents, thickeners, viscosity modifiers, anti-settling agents, anti-dripping agents, anti-skinning agents, dehydrating agents, matting agents, ultraviolet absorbers, light stabilizers, antioxidants, catalysts, curing accelerators, silane coupling agents, etc.

[0031] In the present invention, it is preferable to contain a curing accelerator. As the curing accelerator, a tertiary or quaternary amine compound is suitable. For example, quaternary ammonium salts such as tetramethylammonium bromide and tetrabutylammonium bromide, diazabicyclo compounds such as DBU (1,8-diazabicyclo[5.4.0]undecene-7), DBN (1,5-diazabicyclo[4.3.0]nonene-5), DBU-phenol salt, DBU-octylate, DBU-p-toluenesulfonate, DBU-formate, DBU-phenol novolak resin salt, tertiary amines such as benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol (TAP) and their salts, dimethylurea compounds such as aromatic dimethylurea and aliphatic dimethylurea, etc. can be mentioned. These can be used alone or in combination of two or more. The content of the curing accelerator is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass in the total amount of the coating material (100% by mass).

[0032] In the present invention, it is preferable to contain a silane coupling agent. Thereby, the adhesion of the coating film is enhanced, and the effect of the present invention can be further enhanced. Furthermore, by using the silane coupling agent in combination with the above-mentioned flat extender pigment, the silane coupling agent acts on the surface of the flat extender pigment, so that the effect of the present invention can be further enhanced more.

[0033] Examples of the silane coupling agent 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, mercapto group-containing silane coupling agents, etc. These can be used alone or in combination of two or more. In the present invention, in particular, an epoxy group-containing silane coupling agent is suitable.

[0034] Examples of the epoxy group-containing silane coupling agent 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, 8-glycidoxyoctylmethyldiethoxysilane, and the like.

[0035] 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 coating material. Also, the mixing ratio of the silane coupling agent is preferably 1 to 60% by mass, more preferably 5 to 50% by mass, based on the above-mentioned flat-plate-shaped pigment. In such a case, the above effects can be further enhanced.

[0036] In the present invention, it is preferable to contain a thickener. Examples of the thickener include, for example, organic bentonite, fine silica, surface-treated calcium carbonate, amide wax, hydrogenated castor oil wax, benzylidene sorbitol, metal soap, oxidized polyethylene, polymerized vegetable oil, polycarboxylic acid amine salt, and the like. These can be used alone or in combination of two or more. In the present invention, it is preferable to contain one or more selected from organic bentonite, amide wax, and oxidized polyethylene.

[0037] The content of the thickener is preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, based on the total amount of the coating material (100% by mass). In such a case, the dispersion stability of the zinc powder can be enhanced, and sufficient viscosity can be imparted, which is advantageous for coating workability such as thick coating property and resistance to sagging. As a result, a uniform coating film can be formed, and it is also advantageous in terms of coatability to bolt joints and the like, and more excellent anticorrosive property and corrosion resistance can be exhibited.

[0038] In the present invention, it is preferable to contain a pigment wetting and dispersing agent. As the pigment wetting and dispersing agent, it is preferable to contain a pigment wetting and dispersing agent having an acid value. It is preferable that the acid value of such a pigment wetting and dispersing agent is preferably 10 to 200 mgKOH / g, more preferably 30 to 150 mgKOH / g. Furthermore, it is preferable that the pigment wetting and dispersing agent has an amine value of preferably 100 mgKOH / g or less, more preferably 0 to 30 mgKOH / g. In such a case, the wetting effect on the zinc powder is enhanced, the zinc powder can be uniformly dispersed, and the paint viscosity can be stabilized. As a result, the coating workability is improved, a uniform coating film can be formed, and excellent anticorrosive property and corrosion resistance can be exhibited. The content of the pigment wetting and dispersing agent is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, based on the total amount of the coating material (100% by mass).

[0039] The coating material of the present invention is preferably a multi-component type (for example, two-component type, three-component type, etc.) having a main agent containing an epoxy resin and an amine curing agent. That is, during distribution, the main agent and the curing agent are stored in separate packages, and they may be mixed during use (coating). Also, the above zinc powder and the above flat flaky pigment may be mixed with at least one of the main agent and the curing agent, or may be added when the main agent and the curing agent are mixed. In the present invention, it is preferable to mix with the main agent. Furthermore, the various additives may be mixed with at least one of the main agent and the curing agent according to various purposes.

[0040] The coating material of the present invention is suitable as an anticorrosive primer material applied to the surface coating of structures that require corrosion protection, such as buildings and civil engineering structures. Specifically, for example, roads, bridges, railways, harbors, buildings, factories, prefabricated houses, power plants, iron towers, amusement parks, swimming pools, and other entertainment and amusement facilities can be mentioned.

[0041] When applying (painting) the coating material of the present invention to a substrate, for example, coating tools such as sprayers, rollers, and brushes can be used. The coating amount during painting is preferably 30 to 500 g / m 2 and more preferably 50 to 300 g / m 2 . Also, the dry film thickness is preferably 30 to 100 μm. The number of coating times can be set as appropriate, but is preferably 1 to 2 times.

[0042] It is preferable to form an anticorrosive coating film structure by further applying various coating materials (for example, undercoating materials, intermediate coating materials, top coating materials, etc.) on the anticorrosive primer formed by the coating material of the present invention. Such coating materials include, for example, those containing a resin component and various pigments (one or more selected from coloring pigments, extender pigments, and rust preventive pigments). Such coating materials are suitable in terms of improving anticorrosion properties, weather resistance, etc., and imparting aesthetic properties with various colors.

[0043] As the resin component in the above coating materials (undercoating materials, intermediate coating materials, top coating materials), various resins can be used. Examples of the types of resins 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 preferable. Also, 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 film can be improved.

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

[0045] As the coloring pigment, known coloring pigments can be used. For example, titanium oxide, zinc oxide, carbon black, graphite, black iron oxide, copper chromium black, cobalt black, copper manganese iron black, red iron oxide, molybdate orange, permanent red, permanent carmine, anthraquinone red, perylene red, quinacridone red, yellow iron oxide, titanium yellow, fast yellow, benzimidazolone yellow, chrome green, cobalt green, phthalocyanine green, ultramarine blue, navy blue, cobalt blue, phthalocyanine blue, quinacridone violet, dioxazine violet, etc. can be mentioned. By appropriately using one or more of these coloring pigments, the color tone of the coating film can be adjusted.

[0046] Examples of the extender pigment include heavy calcium carbonate, light calcium carbonate, kaolin, clay, pottery clay, china clay, diatomaceous earth, hydrated fine silica powder, barite powder, barium sulfate, precipitated barium sulfate, barium carbonate, magnesium carbonate, silica powder, aluminum hydroxide, etc. One or more of these can be used.

[0047] Examples of the rust preventive pigment include phosphate compounds such as zinc phosphate, iron phosphate, aluminum phosphate, calcium phosphate, and magnesium phosphate; phosphite 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; molybdate compounds such as zinc molybdate, aluminum molybdate, calcium molybdate, barium molybdate, and aluminum phosphomolybdate; vanadium compounds such as vanadium oxide; borate compounds such as barium borate, barium metaborate, and calcium borate; cyanamide compounds such as zinc cyanamide and calcium zinc cyanamide. One or more of these can be used. The rust preventive pigment preferably has an average particle diameter of 10 μm or less (more preferably 0.05 μm or more and 5 μm or less, still more preferably 0.1 μm or more and 3 μm or less).

[0048] Such coating materials may contain various components other than the above components as long as the effects of the present invention are not significantly impaired. Examples of such components include thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreezing agents, pH adjusters, antiseptics, antifungal agents, algicides, antibacterial agents, dispersants, defoamers, adsorbents, fibers, crosslinking agents, ultraviolet absorbers, antioxidants, low-pollution agents, water repellents, catalysts, solvents, water, and the like. The coating materials can be produced by uniformly mixing the above resin components, pigments, and various components as required by a conventional method.

[0049] In the application of each coating material, known coating tools can be used. Examples of the coating tools include sprays, rollers, brushes, and the like. The coating amount of each coating material may be appropriately set according to the coating material, but is preferably 50 to 500 g / m 2 , more preferably 80 to 400 g / m 2 . During coating, it can be appropriately diluted as required. The number of coating times of the coating material is preferably 1 to 2 times.

Examples

[0050] Examples and comparative examples are shown below to clarify the features of the present invention.

[0051] ·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 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) 125 g / eq ·Amine curing agent 2: Mannich-modified epoxy adduct amine, solid content 100% by mass, active hydrogen equivalent (solid content) 85 g / eq ·Zinc powder 1: Granular zinc powder (average particle diameter 5 μm, specific gravity 7.1) ·Zinc powder 2: Granular zinc powder (average particle diameter 8 μm, specific gravity 7.1) ·Flat-plate extender pigment 1: Talc (average particle diameter 10 μm, specific gravity 2.7, Mohs hardness 1) ·Flat-plate extender pigment 2: Talc (average particle diameter 15 μm, specific gravity 2.7, Mohs hardness 1) ·Flat-plate extender pigment 3: Talc (average particle diameter 3 μm, specific gravity 2.7, Mohs hardness 1) ·Pigment wetting and dispersing agent: Copolymer having an acidic group (acid value 101 mgKOH / g) ·Silane coupling agent: γ-Glycidoxypropyltriethoxysilane ·Curing accelerator: 2,4,6-Tris(dimethylaminomethyl)phenol (Others) ·Additive 1: Thickening agent (amide wax, organic bentonite, polyethylene oxide), defoaming agent, etc. ·Additive 2: Thickening agent (amide wax, organic bentonite), defoaming agent, etc. ·Additive 3: Thickening agent (amide wax), defoaming agent, etc. ·Solvent: Aromatic hydrocarbon solvent, alcohol solvent, etc.

[0052] (Examples 1 to 16, Comparative examples 1 to 4) According to the formulations shown in Tables 1 and 2, after preparing the main agent and the curing agent, these were mixed to produce zinc-rich paints 1 to 20. For each of the produced zinc-rich paints, the following evaluations were carried out. The results are shown in Table 3.

[0053] <Curability> Zinc-rich paint was spray-coated on a grid-blasted steel plate SS400 (300 mm × 150 mm × 3.2 mm) so that the coating amount was 300 g / m 2 and dried at 23°C for 6 hours. The resulting product was used as a test specimen. Using the prepared test specimens, a curing and drying test was carried out according to JIS K 5600-3-3:1999, and the occurrence state of abnormalities (scratches or marks on the coating film) was confirmed. The evaluation criteria were set as a four-level system (a > b > c > d), where those without abnormalities were rated as "a" and those with obvious abnormalities were rated as "d".

[0054] <Weather resistance (outdoor exposure weathering test)> Zinc-rich paint was spray-coated on a grid-blasted steel plate SS400 (300 mm × 150 mm × 3.2 mm) so that the coating amount was 300 g / m 2 and dried at 23°C for 24 hours. Then, the sides and back of the test piece were coated with the same paint and dried at 23°C for 6 days. The resulting product was used as a test specimen. The prepared test specimens were exposed outdoors (for 2 years) at a 45-degree inclination facing south in Ibaraki City, Osaka Prefecture, and the occurrence state of abnormalities (rust, swelling, cracking, and peeling) was confirmed. The evaluation criteria were set as a four-level system (a > b > c > d), where those without abnormalities were rated as "a" and those with obvious abnormalities were rated as "d".

[0055] <Corrosion resistance (salt spray test)> Zinc-rich paint was spray-coated on a grid-blasted steel plate SS400 (300 mm × 150 mm × 3.2 mm) so that the coating amount was 300 g / m 2 and dried at 23°C for 24 hours. Then, the sides and back of the test piece were coated with the same paint and dried at 23°C for 6 days. The resulting product was used as a test specimen. The fabricated test specimens were subjected to a neutral salt spray resistance test in accordance with JIS K5600-7-1:1999, and the occurrence status of abnormalities (rust, swelling, cracking, and peeling) was confirmed. The evaluation criteria were divided into four levels (a > b > c > d), where "a" indicates no abnormalities were observed, and "d" indicates obvious abnormalities were observed.

[0056] Next, in Examples 1 to 16, the thick coating property and sag resistance were evaluated. The results are shown in Table 3. <Thick coating property> Zinc-rich paint was spray-coated on a grid-blasted steel plate SS400 (300 mm × 150 mm × 3.2 mm) so that the coating amount was 300 g / m 2 and, while it was still undried, the same paint was spray-coated again so that the coating amount was 300 g / m 2 After drying at 23°C for 48 hours, the occurrence status of coating film abnormalities (sagging, cracking, and peeling) was confirmed. The evaluation criteria were divided into four levels (a > b > c > d), where "a" indicates no abnormalities were observed, and "d" indicates obvious abnormalities were observed.

[0057] <Sag resistance> A base material was prepared by curing the lower end 50 mm of an iron plate (300 mm × 225 mm × 0.3 mm). On the above base material, zinc-rich paint was applied with an applicator so that the wet film thickness was 300 μm. Immediately after application, the curing was removed, the test specimen was held vertically, dried at 23°C for 24 hours, and the length of the sag to the uncoated part was measured. The evaluation criteria are as follows. a: 0 mm b: More than 0 mm and 1.5 mm or less c: More than 1.5 mm and 2.5 mm or less d: More than 2.5 mm

[0058]

Table 1

[0059]

Table 2

[0060]

Table 3

Claims

1. A coating material containing a resin component and zinc powder, and containing 70% by mass or more of zinc powder in the heat residue, wherein the coating material contains a flat-plate extender pigment, and the average particle diameter of the flat-plate extender pigment is larger than the average particle diameter of the zinc powder.

2. The coating material according to Claim 1, wherein the content of the flat-plate extender pigment with respect to the zinc powder is 0.1 to 10% by mass.

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