Rust-preventive paint composition, painted article, and method for manufacturing a painted article

Abstract

The present invention provides a rust-preventive coating composition that can impart excellent rust prevention properties even to steel materials with residual rust or salt. [Solution] A rust-preventive paint composition comprising an epoxy resin (a), a polyamine (b), a powder (c), and a thickener (d), wherein the powder (c) comprises a metal sulfate (c-1) whose solubility in 100 g of water at 5°C is 0.1 g or more, and a zinc compound (c-2) whose solubility in 100 g of water at 20°C at pH 7.0 is less than 0.03 g, and whose solubility in 100 g of water at 20°C at pH 4.0 is 0.03 g or more, wherein the content of the metal sulfate (c-1) is 0.2% by mass or more and 70% by mass or less based on 100 parts by mass of the resin solids of the rust-preventive paint composition, and the content of the zinc compound (c-2) is 10% by mass or more and 200% by mass or less based on 100 parts by mass of the resin solids of the rust-preventive paint composition.

Description

Technical Field

[0001] The present invention relates to a rust preventive paint composition, a painted article, and a method for manufacturing a painted article.

Background Art

[0002] Patent Document 1 discloses a paint containing a metal sulfate and at least one metal powder selected from the group consisting of zinc and zinc alloys.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When repainting steel materials, first, surface treatment such as pickling is performed on deteriorated paint films and corroded parts. In particular, sufficiently removing rust from corroded parts is important for rust prevention management. However, rust in complex structural parts such as around bolts or at welded intersections, or on structures at high altitudes or on the ocean, may be difficult to remove sufficiently. Therefore, there is a demand for a paint that can provide high rust prevention even when applied to steel materials with remaining rust.

[0005] Also, in areas where salt (sea salt) drifts, such as coastal areas, salt accelerates the corrosion of steel materials. Therefore, it is desirable to repaint after sufficiently removing the salt. However, removing the salt adhering to structures installed outdoors requires a great deal of labor. Therefore, there is a demand for a paint that can provide high rust prevention even when applied to steel materials with remaining salt.

[0006] An object of the present invention is to provide a rust preventive paint composition that can impart excellent rust prevention to steel materials with remaining rust or salt.

Means for Solving the Problem

[0007] The present invention provides the following aspects. [1] An anti-rust paint composition containing an epoxy resin (a), a polyamine (b), a powder (c), and a thickener (d), wherein the powder (c) contains a metal sulfate (c-1) having a solubility of 0.1 g or more in 100 g of water at 5°C, and a zinc compound (c-2) having a solubility of less than 0.03 g in 100 g of water at 20°C and pH 7.0, and a solubility of 0.03 g or more in 100 g of water at 20°C and pH 4.0, the content of the metal sulfate (c-1) is 0.2% by mass or more and 70% by mass or less based on 100 parts by mass of the resin solid content of the anti-rust paint composition, the content of the zinc compound (c-2) is 10% by mass or more and 200% by mass or less based on 100 parts by mass of the resin solid content of the anti-rust paint composition. [2] The anti-rust paint composition according to [1] above, wherein the mass ratio (c-1 / c-2) of the content of the metal sulfate (c-1) to the content of the zinc compound (c-2) is from 0.08 / 99.92 to 90.00 / 10.00. [3] The anti-rust paint composition according to [1] above, which is for steel materials having rust on the surface. [4] The anti-rust paint composition according to [1] above, which is for steel materials having salt on the surface. [5] The anti-rust paint composition according to [1] above, wherein the metal sulfate (c-1) is a salt of a polyvalent metal cation and a sulfate ion. [6] The rust-preventive coating composition of [1] above, wherein the metal sulfate (c-1) comprises at least one selected from the group consisting of nickel sulfate, aluminum sulfate, magnesium sulfate, zinc sulfate, cobalt sulfate, chromium sulfate, copper sulfate, titanium sulfate, tin sulfate, zirconium sulfate, vanadium sulfate, and manganese sulfate. [7] The rust-preventive coating composition of [1] above, wherein the zinc compound (c-2) comprises at least one selected from the group consisting of zinc oxide, zinc hydroxide, and zinc carbonate. [8] The rust-preventive coating composition of [1] further comprises, the powder (c) a rust-preventive coating composition of the above [1], wherein the powder (c) further comprises an alkaline earth metal compound (c-3) which is at least one of an alkaline earth metal oxide and an alkaline earth metal hydroxide. [9] The rust-preventive paint composition according to [8] above, wherein the content of the alkaline earth metal compound (c-3) is 0.15% by mass or more and 40% by mass or less based on 100 parts by mass of the resin solids of the rust-preventive paint composition.

[10] The rust-preventive coating composition according to [8] above, wherein the alkaline earth metal compound (c-3) comprises at least one selected from the group consisting of calcium oxide, calcium hydroxide, barium oxide, and barium hydroxide.

[11] The rust-preventive paint composition according to [1] above, wherein, under conditions of a solid content concentration of 69% by mass and a temperature of 25°C, the viscosity measured using a rheometer is 0.1 Pa·s or more and 1.2 Pa·s or less after 1 minute when shear stress is applied at a shear rate of 1000 (1 / s), and the viscosity measured at 40 Pa·s or more and 500 Pa·s or less after 1 minute when shear stress is applied at a shear rate of 0.1 (1 / s).

[12] Steel material with rust on the surface, A painted article comprising a rust-preventive coating film formed on the steel material with any of the rust-preventive coating compositions [1] to

[11] above.

[13] The painted article according to

[12] above, wherein the thickness of the rust on the surface of the steel material is 10 μm or more and 200 μm or less.

[14] The painted article

[13] wherein the rust-preventive coating covers the rust on the surface of the steel material.

[15] Steel material having salt on its surface, A painted article comprising a rust-preventive coating film formed on the steel material with any of the rust-preventive coating compositions [1] to

[11] above.

[16] A method for manufacturing a painted article, comprising applying one of the rust-preventive paint compositions [1] to

[11] above onto a steel material having rust on its surface.

[17] A method for manufacturing a painted article, comprising applying one of the rust-preventive paint compositions [1] to

[11] above onto a steel material having salt on its surface. [Effects of the Invention]

[0008] The present invention provides a rust-preventive coating composition that can impart excellent rust prevention properties even to steel materials with residual rust or salt. [Modes for carrying out the invention]

[0009] The rust-preventive coating composition of this disclosure comprises an epoxy resin (a), a polyamine (b), a powder (c), and a thickener (d). The powder (c) comprises a metal sulfate (c-1) whose solubility in 100 g of water at 5°C is 0.1 g or more, and a zinc compound (c-2) whose solubility in 100 g of water at 20°C at pH 7.0 is less than 0.03 g, and whose solubility in 100 g of water at 20°C at pH 4.0 is 0.03 g or more.

[0010] The content of metal sulfate (c-1) is 0.2% by mass or more and 70% by mass or less per 100 parts by mass of resin solids in the rust-preventive coating composition. The content of zinc compound (c-2) is 10% by mass or more and 200% by mass or less per 100 parts by mass of resin solids in the rust-preventive coating composition.

[0011] Metal sulfate (c-1) dissolves in aqueous solution, eluting metal ions and sulfate ions. Subsequently, hydrogen ions are generated due to the acidic action of the eluted sulfate ions and the hydrolysis of the metal ions. The generated hydrogen ions dissolve zinc compound (c-2), generating zinc ions. The generated zinc ions react with chloride ions contained in airborne salt, rainwater, or rust present on the surface of the substrate, trapping (capturing) the chloride ions. During this reaction, compounds such as basic zinc chloride are produced by the reaction between zinc ions and chloride ions. These products form a water-stable film (hereinafter referred to as the "rust-preventive layer") in the coating. This rust-preventive layer provides a rust-preventive effect.

[0012] Zinc compound (C-2) exhibits rust-preventive effects even when used alone. This is because zinc ions leached from zinc compound (C-2) contribute to rust prevention. On the other hand, it is known that the amount of zinc compound (C-2) present does not correlate with the rust-preventive effect. This is because there is a limit to the amount of zinc ions that can be leached.

[0013] It was found that the metal sulfate (C-1) promotes the elution of zinc ions from the zinc compound (C-2). In other words, more zinc ions can be eluted when combined with the metal sulfate (C-1) than when the zinc compound (C-2) is used alone, promoting the formation of a rust-preventive layer and improving rust prevention. Therefore, the rust-preventive coating composition of this disclosure can be used on steel materials that have rust or salt on their surface. High rust prevention can be imparted to such steel materials.

[0014] (Rust-preventive paint composition) The rust-preventive paint composition may be a two-component type comprising a main component containing epoxy resin (a) and a curing agent containing polyamine (b). The powder (c) may be contained in the main component, in the curing agent, or in both. The powder (c) may be contained in the main component.

[0015] Below, epoxy equivalent is determined based on the solid content mass. Epoxy equivalent is determined in accordance with JIS K 7236:2009.

[0016] The weight-average molecular weight is measured by gel permeation chromatography (GPC).

[0017] The active hydrogen equivalent of polyamines is determined based on the solid content mass. The active hydrogen equivalent of polyamines is determined in accordance with JIS K 7237:1995.

[0018] The solid content of a rust-preventive paint composition is the total components of the paint composition excluding volatile components (typically the solvent). The solid content concentration of a rust-preventive paint composition can be calculated from the residue after heating the paint composition at 105°C for 1 hour, in accordance with the JIS K 5601-1-2:2008 heating residue measurement method.

[0019] The solid content concentration of the rust-preventive coating composition is not particularly limited. For example, the solid content concentration of the rust-preventive coating composition may be 60% by mass or more and 75% by mass or less. The solid content concentration of the rust-preventive coating composition may be 65% by mass or more and 68% by mass or more. The solid content concentration of the rust-preventive coating composition may be 73% by mass or less and 71% by mass or less.

[0020] • Epoxy resin (a) The epoxy resin (a) is a film-forming component. The epoxy resin (a) cross-links with the polyamine (b) to form a cured coating film.

[0021] The epoxy resin (a) is not particularly limited. Examples of epoxy resin (a) include aromatic epoxy resins such as bisphenol type, novolac type, biphenyl type, and naphthalene type; and aliphatic epoxy resins such as dicyclopentadiene type and glycidyl ethers of polyhydric alcohols. These can be used individually or in combination of two or more. Epoxy resin (a) may be a modified form of the above-mentioned epoxy resin. In terms of moisture resistance and toughness, it may be an aromatic epoxy resin or a novolac type epoxy resin.

[0022] Examples of bisphenol-type epoxy resins include bisphenol A, bisphenol F, bisphenol S, bisphenol AD, diglycidyl ethers of alkylene oxide adducts of these bisphenol-type epoxy resins, and hydrogenated bisphenol types obtained by adding hydrogen to these bisphenol-type epoxy resins. These can be used individually or in combination of two or more types.

[0023] Examples of novolac-type epoxy resins include phenol novolac type, cresol novolac type, and bisphenol A novolac type. These can be used individually or in combination of two or more types.

[0024] Examples of biphenyl, naphthalene, and dicyclopentadiene types include resins in which one or more glycidyl ether groups are substituted at any position on biphenyl, naphthalene, or dicyclopentadiene. These can be used individually or in combination of two or more.

[0025] The solid content of epoxy resin (a) is, for example, 15% by mass or more and 60% by mass or less of the solid content of the rust-preventive coating composition. When the above content of epoxy resin (a) is 15% by mass or more, the curability may be improved. When the above content of epoxy resin (a) is 60% by mass or less, the relative proportion of pigment in the coating film increases, and therefore the opacity may be improved. The above content of epoxy resin (a) may be 20% by mass or more, and may be 25% by mass or more. The above content of epoxy resin (a) may be 50% by mass or less, and may be 40% by mass or less.

[0026] The weight-average molecular weight of epoxy resin (a) is not particularly limited. The weight-average molecular weight of epoxy resin (a) may be between 6500 and 10000, in that it enhances curability (especially curability at low temperatures of 5°C or below). The weight-average molecular weight of epoxy resin (a) may be 8500 or more. The weight-average molecular weight of epoxy resin (a) may be 10000 or less.

[0027] The epoxy equivalent of epoxy resin (a) is not particularly limited. The epoxy equivalent of epoxy resin (a) may be 1000 g / eq or more and 1400 g / eq or less, in order to improve curability at low temperatures. The epoxy equivalent of epoxy resin (a) may be 1100 g / eq or more.

[0028] Examples of commercially available novolac-type epoxy resins (a) include the product name "EPICLON 5970-60" (phenol novolac-type epoxy resin, weight-average molecular weight 9500, solids content 60% by mass, epoxy equivalent 1000 g / eq or more, manufactured by DIC Corporation). Examples of commercially available bisphenol A-type epoxy resins (a) include the product name "EPICLON 1040-70X" (bisphenol A-type epoxy resin, solids content 70% by mass, epoxy equivalent 1300 g / eq, manufactured by DIC Corporation).

[0029] • Polyamine (b) Polyamine (b) is the curing component. Polyamine (b) crosslinks with epoxy resin (a) to form a cured coating film.

[0030] Polyamine (b) is not particularly limited. Polyamine (b) may be an alicyclic polyamine (b-1) having a cyclic aliphatic hydrocarbon group to which an amino group is bonded, or a non-alicyclic polyamine (b-2) not having a cyclic aliphatic hydrocarbon group to which an amino group is bonded, or it may contain both. When alicyclic polyamine (b-1) and non-alicyclic polyamine (b-2) are used in combination, when another coating is laminated on the rust-preventive coating formed by the rust-preventive coating composition, the dissolution and lifting of the rust-preventive coating is more easily suppressed.

[0031] Examples of alicyclic polyamines (b-1) include 1,4-cyclohexanediamine, 4,4'-methylenebiscyclohexylamine, 4,4'-isopropylidenebiscyclohexylamine, norbornadiamine, bis(aminomethyl)cyclohexane, diaminodicyclohexylmethane, isophoronediamine, mensendiamine (MDA), and 1,3-bis(aminomethyl)cyclohexane. These can be used individually or in combination of two or more.

[0032] The active hydrogen equivalent of alicyclic polyamine (b-1) is, for example, 30 g / eq to 150 g / eq. When the active hydrogen equivalent of alicyclic polyamine (b-1) is 30 g / eq or higher, the curability may be improved. When the active hydrogen equivalent of alicyclic polyamine (b-1) is 150 g / eq or lower, the barrier function may be improved. The active hydrogen equivalent of alicyclic polyamine (b-1) may be 32 g / eq or higher, or 33 g / eq or higher. The active hydrogen equivalent of alicyclic polyamine (b-1) may be 100 g / eq or lower, or 50 g / eq or lower. Barrier function refers to the ability to prevent corrosive factors such as water, oxygen, and ions from reaching the surface of the metal substrate.

[0033] Examples of non-alicyclic polyamines (b-2) include linear aliphatic polyamines, polyamines having an aromatic ring to which an amino group is attached (aromatic polyamines), and polyamines having a heterocyclic ring to which an amino group is attached (heterocyclic polyamines). These can be used individually or in combination of two or more.

[0034] Examples of linear aliphatic polyamines include alkylene polyamines and polyalkylene polyamines. Examples of alkylene polyamines include H2N-R 1 -NH2(wherein, R 1is a divalent hydrocarbon group having 1 to 12 carbon atoms, which may be substituted with one or more hydrocarbon groups having 1 to 10 carbon atoms, and may be branched. ) is represented as ). Examples of alkylene polyamines include methylenediamine, ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, and 1,10-diaminodecane. Examples of polyalkylene polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and hexamethylenetetramine. These can be used individually or in combination of two or more.

[0035] Other examples of linear aliphatic polyamines include tetra(aminomethyl)methane, tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2'-aminoethylamino)propane, triethylene-bis(trimethylene)hexamine, bis(3-aminoethyl)amine, and bishexamethylenetriamine [H2N(CH2)6NH(CH2)6NH2]. These can be used individually or in combination of two or more.

[0036] Examples of aromatic polyamines include bis(aminoalkyl)benzene, bis(aminoalkyl)naphthalene, and compounds having two or more primary amino groups bonded to a benzene ring. Examples of aromatic polyamines include bis(cyanoethyl)diethylenetriamine, o-xylylenediamine, m-xylylenediamine (MXDA), p-xylylenediamine, phenylenediamine, naphthylenediamine, diaminodiphenylmethane, diaminodiethylphenylmethane, 2,2-bis(4-aminophenyl)propane, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylsulfone, 2,2'-dimethyl-4,4'-diaminodiphenylmethane, 2,4'-diaminobiphenyl, 2,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, bis(aminomethyl)naphthalene, and bis(aminoethyl)naphthalene. These can be used individually or in combination of two or more types.

[0037] Examples of heterocyclic polyamines include N-methylpiperazine [CH3-N(CH2CH2)2NH], morpholine [HN(CH2CH2)2O], 1,4-bis-(8-aminopropyl)-piperazine, piperazine-1,4-diazacycloheptane, 1-(2'-aminoethylpiperazine), 1-[2'-(2''-aminoethylamino)ethyl]piperazine, 1,11-diazacycloeicosane, and 1,15-diazacyclooctacosane. These can be used individually or in combination of two or more.

[0038] The active hydrogen equivalent of non-alicyclic polyamine (b-2) is, for example, 30 g / eq or more and 550 g / eq or less. The active hydrogen equivalent of non-alicyclic polyamine (b-2) may be 32 g / eq or more, and may be 35 g / eq or more. The active hydrogen equivalent of non-alicyclic polyamine (b-2) may be 250 g / eq or less, 100 g / eq or less, and may be 50 g / eq or less.

[0039] The solid content of polyamine(b) is, for example, 0.6% by mass or more and 15% by mass or less of the solid content of the rust-preventive coating composition. When the above content of polyamine(b) is 0.6% by mass or more, the curability may be improved. When the above content of polyamine(b) is 15% by mass or less, the barrier function may be improved. The above content of polyamine(b) may be 0.8% by mass or more, or 0.9% by mass or more. The above content of polyamine(b) may be 10% by mass or less, 5.0% by mass or less, or 2.0% by mass or less.

[0040] The solid content of alicyclic polyamine (b-1) is, for example, 0.5% by mass or more and 10% by mass or less of the solid content of the rust-preventive paint composition. When the above content of alicyclic polyamine (b-1) is 0.5% by mass or more, curability at low temperatures may be improved in particular. When the above content of alicyclic polyamine (b-1) is 10% by mass or less, the tackiness (adhesion) of the resulting coating film may be reduced and the traction may be improved. The above content of alicyclic polyamine (b-1) may be 0.6% by mass or more, 0.7% by mass or more, or 0.75% by mass or more. The above content of alicyclic polyamine (b-1) may be 8.0% by mass or less, 6.0% by mass or less, or 2.0% by mass or less. Traction refers to the performance in which, when a worker walks on the coating film, it is difficult for shoe marks to be formed on the coating film and the peeling of the coating film is small.

[0041] The solid content of the non-alicyclic polyamine (b-2) is, for example, 0% by mass or more and 10% by mass or less of the solid content of the rust-preventive coating composition. When the above content of non-alicyclic polyamine (b-2) is 10% by mass or less, the tackiness of the resulting coating film at low temperatures may be reduced and the traction may be improved. The above content of non-alicyclic polyamine (b-2) may be 0.1% by mass or more, or 0.15% by mass or more. The above content of non-alicyclic polyamine (b-2) may be 6.0% by mass or less, 3.0% by mass or less, 2.0% by mass or less, or 1.0% by mass or less.

[0042] • Alkylphenol The curing agent may further contain alkylphenols. Alkylphenols further improve curability (especially low-temperature curability).

[0043] Examples of alkylphenols include monohydric phenols such as methylphenol (o,m,p-cresol), ethylphenol, butylphenol, tert-butylphenol, octylphenol, nonylphenol, dodecylphenol, and dinonylphenol. These can be used individually or in combination of two or more. The number of carbon atoms in the alkyl group of an alkylphenol is, for example, 1 to 10. The above number of carbon atoms may be 5 or less.

[0044] The solid content of alkylphenol is, for example, 0.05% by mass or more and 5.0% by mass or less of the solid content of the rust-preventive paint composition. The above content of alkylphenol may be 0.1% by mass or more, or 0.15% by mass or more. The above content of alkylphenol may be 3.0% by mass or less, 2.0% by mass or less, 1.0% by mass or less, or 0.4% by mass or less.

[0045] ·Powder (c) Powder (c) contains a rust inhibitor. By using a combination of a specific metal sulfate (c-1) and a zinc compound (c-2) as rust inhibitors, excellent rust prevention properties can be obtained as described above.

[0046] The average particle size of powder (c) is, for example, 0.1 μm or more and 40 μm or less. The average particle size of powder (c) may be 5 μm or more. The average particle size of powder (c) may be 20 μm or less.

[0047] The average particle size of powder (c) is calculated as follows: A composition containing epoxy resin (a), polyamine (b), and metal sulfate (c-1) in predetermined proportions is applied to a polished steel plate to form a dry coating film of 100 μm or more, and then dried. The resulting coating film is observed in a cross-section in the thickness direction using a scanning electron microscope (SEM). The maximum diameter in a specific direction of 200 metal sulfate (c-1) particles observed in the image is measured, and the average value is calculated. This average value is the average particle size of the metal sulfate (c-1). The average particle sizes of zinc compounds (c-2) and alkaline earth metal compounds (c-3), described later, can be determined in the same manner.

[0048] • Metal sulfate (c-1) The metal sulfate (c-1) has a solubility of 0.1 g or more in 100 g of water at 5°C. Because metal sulfate (c-1) dissolves readily in water even in low-temperature environments, it can promote the formation of a rust-preventive layer. The above solubility of metal sulfate (c-1) may be 5.0 g or more, or 10.0 g or more.

[0049] The metal sulfate (c-1) may be a salt of a polyvalent metal cation and sulfate ions. When the polyvalent metal cation (hereinafter referred to as polyvalent cation) coexists with iron ions generated from the metal substrate, a dense and electrochemically stable corrosion-preventive layer is formed.

[0050] Examples of metals that constitute metal sulfates (C-1) include alkaline earth metals, transition metals, and post-transition metals. These generate polyvalent cations. They can be used individually or in combination of two or more.

[0051] Alkaline earth metals are elements in Group 2 of the periodic table. Specific examples of alkaline earth metals include magnesium (Mg), calcium (Ca), and strontium (St). Transition metals are metallic elements located between Group 3 and Group 11 of the periodic table. Specific examples of transition metals include scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), and rhodium (Rh). Examples of post-transition metals include palladium (Pd), silver (Ag), cadmium (Cd), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg), rusthordium (Rf), dubnium (Db), seaborgium (Sg), bohrium (Bh), and hassium (Hs). Post-transition metals are metallic elements located in the P block of the periodic table. Specifically, examples of post-transition metals include aluminum (Al), gallium (Ga), indium (In), tin (Sn), thallium (Tl), lead (Pb), bismuth (Bi), polonium (Po), and astatine (At). From the viewpoint of solubility, the metal may be magnesium (Mg), aluminum (Al), nickel (Ni), or zinc (Zn). These can be used individually or in combination of two or more types.

[0052] Examples of metal sulfates (c-1) include nickel sulfate, aluminum sulfate, magnesium sulfate, zinc sulfate, cobalt sulfate, chromium sulfate, copper sulfate, titanium sulfate, tin sulfate, zirconium sulfate, vanadium sulfate, and manganese sulfate. These can be used individually or in combination of two or more.

[0053] The content of metal sulfate (c-1) is 0.2% by mass or more and 70% by mass or less per 100 parts by mass of resin solids in the rust-preventive coating composition. When the above content of metal sulfate (c-1) is 0.2% by mass or more, the effect of metal sulfate (c-1) is exerted. When the above content of metal sulfate (c-1) is 70% by mass or less, the barrier function is further improved, and the physical properties of the coating film are also improved.

[0054] The above content of metal sulfate (c-1) may be 1.0% by mass or more, 2.0% by mass or more, or 4.0% by mass or more. The above content of metal sulfate (c-1) may be 40.0% by mass or less, 20.0% by mass or less, or 15.0% by mass or less.

[0055] • Zinc compounds (c-2) The zinc compound (c-2) donates zinc ions to the coating film. The zinc compound (c-2) has a solubility of less than 0.03 g in 100 g of water at pH 7.0 and 20°C, and a solubility of 0.03 g or more in 100 g of water at pH 4.0 and 20°C.

[0056] The zinc compound (c-2) gradually dissolves in the coating film as the pH changes due to the progression of corrosion of the coated object, forming basic zinc chloride together with chloride ions and other elements. Since zinc chloride is a dense and highly corrosion-resistant compound, it forms a corrosion-preventive layer with high barrier function. In this disclosure, because it is used in combination with metal sulfate (c-1), more zinc ions can be eluted, further promoting the formation of the corrosion-preventive layer.

[0057] Zinc compound (C-2) has low solubility in 100g of water at 20°C in the nearly neutral to alkaline range. Therefore, in environments where corrosion is less likely to occur, the dissolution of zinc compound (C-2) is suppressed. On the other hand, in the acidic range, zinc compound (C-2) has high solubility in 100g of water at 20°C. Zinc compound (C-2) dissolves and exerts its effect when the pH decreases due to the dissolution of metal sulfate (C-1).

[0058] Conventional zinc powders and zinc alloy powders dissolve rapidly due to sacrificial corrosion protection. As a result, the amount of zinc ions in the coating decreases, and sufficient zinc chloride is not formed. In particular, when rust or salt is present on the steel surface, the sacrificial corrosion protection function of the zinc powder or zinc alloy powder is more easily activated due to the supply of moisture from the crystal water contained in the rust or the dissolution (deliquescent) of salt. Therefore, the zinc in the coating is consumed for sacrificial corrosion protection rather than for the formation of zinc chloride, and high rust prevention cannot be obtained.

[0059] Examples of zinc compounds (c-2) include zinc oxide, zinc hydroxide, and zinc carbonate. These can be used individually or in combination of two or more. Zinc oxide may be included for its opacity. Zinc compounds (c-2) do not include metallic zinc, zinc alloys, or zinc sulfate.

[0060] The zinc compound (C-2) may be white. In this case, the color of the finish coating is not restricted, thus increasing the freedom in designing the color of the coating film.

[0061] The content of zinc compound (c-2) is 10% by mass or more and 200% by mass or less per 100 parts by mass of resin solids in the rust-preventive coating composition. If the above content of zinc compound (c-2) is 10% by mass or more, the effect of zinc compound (c-2) is fully exhibited. If the above content of zinc compound (c-2) is 200% by mass or less, the film-forming properties are not impaired.

[0062] The above content of zinc compound (c-2) may be 15.0% by mass or more, 20.0% by mass or more, or 50.0% by mass or more. The above content of zinc compound (c-2) may be 150.0% by mass or less, 120.0% by mass or less, or 110.0% by mass or less.

[0063] The mass-based ratio (c-1 / c-2) of the content of metal sulfate (c-1) to the content of zinc compound (c-2) may be, for example, 0.08 / 99.92 to 90.00 / 10.00. This further promotes the ionization of zinc compound (c-2), allowing for the efficient production of zinc chloride. The ratio (c-1 / c-2) may be 2.50 / 97.50 to 25.00 / 75.00, or 4.00 / 96.00 to 15.00 / 85.00.

[0064] • Alkaline earth metal compounds (c-3) Powder (c) may contain an alkaline earth metal compound (c-3). The alkaline earth metal compound (c-3) is at least one of an oxide and / or hydroxide of an alkaline earth metal. The alkaline earth metal compound (c-3) dissolves in water, eluting alkaline earth metal ions and their counterions. The alkaline earth metal ions react with sulfate ions to form salts that are sparingly soluble in water.

[0065] As mentioned above, sulfate ions promote the formation of a rust-preventive layer, but if they act directly on the coated object, they can promote its corrosion. By combining an alkaline earth metal compound (C-3) with a metal sulfate (C-1), corrosion of the coated object by sulfate ions is suppressed, and the occurrence of red rust is inhibited.

[0066] The amount of alkaline earth metal compound (c-3) that can be dissolved is not particularly limited. The amount of alkaline earth metal compound (c-3) that can be dissolved in 100g of water at 20°C may be 0.05g or more. The above amount of alkaline earth metal compound (c-3) that can be dissolved may be 0.1g or more, or 1.0g or more. From the viewpoint of suppressing the generation of voids due to rapid dissolution, the above amount of alkaline earth metal compound (c-3) that can be dissolved may be 5.0g or less, or 4.0g or less.

[0067] The alkaline earth metal is not particularly limited and may be any of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), or radium (Ra). The alkaline earth metal may be at least one selected from the group consisting of Ca, Sr, and Ba.

[0068] Specific examples of alkaline earth metal compounds (C-3) include calcium oxide, barium oxide, strontium oxide, calcium hydroxide, barium hydroxide, and strontium hydroxide. The alkaline earth metal compound (C-3) may contain at least one selected from the group consisting of calcium oxide, calcium hydroxide, barium oxide, and barium hydroxide. In particular, it may contain calcium oxide.

[0069] The content of alkaline earth metal compound (C-3) is not particularly limited. For example, the content of alkaline earth metal compound (C-3) is 0.15% by mass or more and 40% by mass or less per 100 parts by mass of resin solids in the rust-preventive coating composition. When the above content of alkaline earth metal compound (C-3) is 0.15% by mass or more, the effect of alkaline earth metal compound (C-3) is easily exerted. As alkaline earth metal compound (C-3) dissolves, the coating film may become alkaline. When the above content of alkaline earth metal compound (C-3) is 40% by mass or less, deterioration of the coating film due to an increase in pH is suppressed.

[0070] The above content of alkaline earth metal compound (C-3) may be 0.2% by mass or more, 0.5% by mass or more, or 1.0% by mass or more. The above content of alkaline earth metal compound (C-3) may be 15.0% by mass or less, or 12.0% by mass or less.

[0071] The ratio (c-1 / c-3) of the content of metal sulfate (c-1) to the content of alkaline earth metal compound (c-3) is not particularly limited. The ratio (c-1 / c-3) may be, for example, 4 / 96 or more and 96 / 4 or less on a mass basis. This may further improve corrosion resistance. The ratio (c-1 / c-3) may be 23 / 77 or more, 33 / 67 or more, or 50 / 50 or more. The ratio (c-1 / c-3) may be 94 / 6 or less, 91 / 9 or less, or 86 / 14 or less.

[0072] • Other rust inhibitors (c-4) The powder (c) may contain other rust inhibitors (c-4). Other rust inhibitors (c-4) are not particularly limited, as long as they do not interfere with the effects of the present disclosure. Examples of other rust inhibitors (c-4) include those commonly used as rust inhibitors. Examples of other rust inhibitors (c-4) include zinc, zinc alloys, calcium phosphite, aluminum phosphate, zinc phosphate, zinc molybdate, aluminum molybdate, and aluminum powder. These may be used individually or in combination of two or more.

[0073] The content of other rust inhibitors (c-4) is, for example, 8% by mass or less of the solid content of the rust-preventive paint composition. The above content of other rust inhibitors (c-4) may be 5% by mass or less, 3% by mass or less, or 0% by mass.

[0074] • Thickening agent (d) The thickener (d) adjusts the viscosity of the rust-preventive coating composition (including high shear viscosity and low shear viscosity as described below). The thickener (d) includes thixotropic agents, thixotropic agents, rheology control agents, and viscosity modifiers.

[0075] The content of the thickener (d) is set appropriately according to the other components contained in the rust-preventive paint composition and their amounts. For example, the content of the thickener (d) may be 0.2% by mass or more and 2.5% by mass or less of the solid content of the rust-preventive paint composition. The above content of the thickener (d) may be 0.4% by mass or more and 0.6% by mass or more. The above content of the thickener (d) may be 2.0% by mass or less and 1.0% by mass or less.

[0076] The thickening agent is not limited as long as it is a non-aqueous thickening agent. Examples of thickening agents include inorganic, organic, and composite systems thereof. These can be used individually or in combination of two or more.

[0077] Examples of inorganic thickeners include fine-particle silica, clay-based minerals, and ultrafine-particle precipitated calcium carbonate. These form a finely dispersed colloidal structure.

[0078] Examples of organic thickeners include metal soaps, hydrogenated castor oils, polyamide waxes, oxidized polyethylenes, vegetable oils / polymerized oils, and surfactants. These form network structures, colloidal dispersion structures, or aggregated structures through adsorption to pigments, etc.

[0079] Examples of organic-inorganic composite thickeners include organic bentonite-based and surface-treated calcium carbonate-based thickeners. These form a finely dispersed colloidal structure.

[0080] In particular, polyamide wax-based thickeners are suitable because they easily provide optimal thixotropy. Thixotropy is the property of readily developing viscosity at low shear and less readily developing viscosity at high shear.

[0081] Pigments Rust-preventive paint compositions may contain pigments. Examples of pigments include those commonly used in paint compositions, without limitation. Examples of pigments include extender pigments and coloring pigments. These may be used individually or in combination of two or more.

[0082] The rust-preventive paint composition may contain a white pigment. The white pigment improves the opacity of the rust-preventive paint composition while minimizing its effect on the hue of the topcoat. If the rust-preventive paint composition has sufficient opacity, the white pigment does not need to be included. Titanium dioxide is a typical example of a white pigment. The amount of white pigment is not particularly limited. For example, the amount of white pigment may be 5% by mass or more and 60% by mass or less of the solid content of the rust-preventive paint composition. The above amount of white pigment may be 10% by mass or more, 15% by mass or more, or 20% by mass or more. The above amount of white pigment may be 40% by mass or less and 30% by mass or less.

[0083] • Body pigments Examples of extender pigments include talc, clay, calcium carbonate, magnesium carbonate, barium sulfate, silicic acid, silicates, aluminum oxide hydrate, calcium sulfate, gypsum, mica-like iron oxide (MIO), glass flakes, szolite mica, and clarite mica. These can be used individually or in combination of two or more. The content of extender pigments is not particularly limited.

[0084] • Colored pigments other than white Examples of coloring pigments include carbon black, graphite, zinc sulfide, chromium oxide, yellow nickel titanium, yellow chromium titanium, yellow iron oxide, red iron oxide, black iron oxide, phthalocyanine blue, phthalocyanine green, ultramarine blue, quinacridones, and azo red and yellow pigments. These can be used individually or in combination of two or more. The content of the coloring pigments is not particularly limited.

[0085] The total content of powder (C) and various pigments is, for example, 30% to 60% as pigment volume concentration (PVC). This ensures opacity while suppressing the occurrence of cracking in the coating and a decrease in adhesion. PVC is the volume percentage (%) of the total amount of powder (C) and various pigments relative to the volume of solids in the rust-preventive coating composition.

[0086] Other resins The rust-preventive paint composition may contain resins other than epoxy resin (a). Examples of other resins include xylene resin, acrylic resin, and polyester resin. These may be used individually or in combination of two or more.

[0087] ·solvent The rust-preventive paint composition may contain a solvent. The solvent content is, for example, 5% by mass or more and 50% by mass or less of the total mass of the rust-preventive paint composition.

[0088] Examples of solvents include those commonly used in the field. These include toluene, xylene, isobutyl alcohol, methyl ethyl ketone, and weak solvents. These can be used individually or in combination of two or more.

[0089] The rust-preventive paint composition may contain a weak solvent. The amount of the weak solvent is, for example, 5% by mass or more and 50% by mass or less of the total mass of the rust-preventive paint composition.

[0090] Weak solvents are aliphatic hydrocarbon compounds. Examples of weak solvents include single-component systems such as n-butane, n-hexane, n-heptane, n-octane, isononane, n-decane, n-dodecane, cyclopentane, cyclohexane, and cyclobutane; and mixed systems such as mineral spirits, white spirits, mineral turpentine, isoparaffin, solvent kerosene, aromatic naphtha, VM&P naphtha, and solvent naphtha. These can be used individually or in combination of two or more.

[0091] Examples of commercially available weak solvents include "Solvesso 100," "Solvesso 150," and "Solvesso 200" (all brand names, manufactured by Esso Petroleum Co., Ltd.), and "Swazol 310," "Swazol 1000," and "Swazol 1500" (all brand names, manufactured by Cosmo Oil Co., Ltd.).

[0092] ·others The rust-preventive paint composition may contain other components. Examples of other components include silane coupling agents and various additives.

[0093] Silane coupling agents improve the adhesion between the rust-preventive coating film and the metal substrate. Silane coupling agents may have at least one of a trimethoxysilyl group and a triethoxysilyl group. The content of the silane coupling agent may be 0.5% by mass or more and 5% by mass or less based on the total mass of the rust-preventive coating composition.

[0094] Examples of additives include anti-sagging agents, anti-settling agents, anti-color separation agents, defoaming agents, anti-smudging agents, leveling agents, and matting agents.

[0095] ·Preparation method A two-component rust-preventive paint composition is prepared by mixing a main component, a hardener, and, if necessary, diluents, etc., in the manner described above. The mixing of the main component and the hardener is usually done immediately before use (for example, within 60 minutes after mixing each component). The solvents described above can also be used as examples of diluents.

[0096] The main component is prepared by mixing the above-mentioned components in a manner known to those skilled in the art. For mixing, commonly used mixing equipment such as a paint shaker or mixer is used. The method for preparing the hardener is similar.

[0097] Shear viscosity The rust-preventive coating composition of this disclosure may have a viscosity of 0.1 Pa·s or more and 1.2 Pa·s or less after 1 minute when shear stress is applied at a shear rate of 1000 (1 / s) under conditions of a solid content concentration of 69% by mass and a temperature of 25°C, as measured using a rheometer, and may also have a viscosity of 40 Pa·s or more and 500 Pa·s or less after 1 minute when shear stress is applied at a shear rate of 0.1 (1 / s).

[0098] The shear rate of 1000 (1 / s) is set based on the assumed shear stress applied to the rust-preventive paint composition during painting. A viscosity of 1.2 Pa·s or less one minute after applying shear stress at a shear rate of 1000 (1 / s) to the rust-preventive paint composition (hereinafter referred to as "high shear viscosity") indicates that the rust-preventive paint composition has sufficiently low viscosity during painting. Therefore, the rust-preventive paint composition can penetrate even into the depressions on the steel surface. A high shear viscosity of 0.1 Pa·s or more indicates that the rust-preventive paint composition has appropriate viscosity during painting. Therefore, the rust-preventive paint composition can adhere to and remain on the protrusions on the steel surface.

[0099] The shear rate of 0.1 (1 / s) is set based on the assumed shear stress applied to the rust-preventive coating composition during leveling after painting. A viscosity of 40 Pa·s or higher one minute after applying shear stress at a shear rate of 0.1 (1 / s) to the rust-preventive coating composition (hereinafter referred to as "low shear viscosity") indicates that the rust-preventive coating composition has appropriate viscosity during leveling. Therefore, the rust-preventive coating composition can harden while covering the protrusions on the steel surface without flowing off them. A low shear viscosity of 500 Pa·s or lower indicates that the rust-preventive coating composition has a low viscosity sufficient for leveling. Therefore, a smooth rust-preventive coating film can be obtained with the rust-preventive coating composition, improving the appearance.

[0100] Because the rust-preventive paint composition has an appropriate viscosity during both application and leveling, it can, for example, cover recesses and protrusions on the surface of steel materials. As a result, further rust formation is suppressed, and rust prevention is further improved.

[0101] High and low shear viscosities are measured using a rheometer (e.g., Anton Paar, product name "MCR-302") at a temperature of 25°C (liquid temperature of 25°C ± 3°C) with a rust-preventive coating composition adjusted to a solid content concentration of 69% by mass. Concentration adjustment is performed by adding an appropriate solvent or removing any solvent already present.

[0102] The high-shear viscosity is the viscosity (Pa·s) after 1 minute from the start of applying shear stress to the rust preventive coating composition after concentration adjustment at a shear rate of 1000 (1 / s). The high-shear viscosity may be 0.2 Pa·s or more, and may be 0.40 Pa·s or more. The high-shear viscosity may be 1.00 Pa·s or less, and may be 0.90 Pa·s or less.

[0103] The low-shear viscosity is the viscosity (Pa·s) after 1 minute from the start of applying shear stress to the rust preventive coating composition after concentration adjustment at a shear rate of 0.1 (1 / s). The low-shear viscosity may be 70 Pa·s or more, and may be 100 Pa·s or more. The low-shear viscosity may be 250 Pa·s or less, and may be 150 Pa·s or less.

[0104] The high-shear viscosity and the low-shear viscosity can be adjusted by the above thickener.

[0105] ·Hue The rust preventive coating composition is usually used as a primer (rust prevention). In recent years, due to the diversification of uses and preferences and the pursuit of originality, the designs required for finish coating cover a wide range. The ability to select the design of the finish coating without being limited to the rust preventive color is one of the important selling points for consumers.

[0106] The L of the rust preventive coating film with a thickness of 60 μm formed by the rust preventive coating composition of the present disclosure * a * b * value in the colorimetric system, the L * value, a * value and b * value are L * ≧70, 0≦a * ≦5.0, and 0≦b * ≦5.0 may satisfy.

[0107] Rust-preventive coatings that meet the above criteria have a hue that can accommodate light-colored topcoats. In other words, they offer a high degree of freedom in color design, allowing the finish coat to have the desired design. For example, by using a white zinc compound (C-2), the hue of the rust-preventive coating can be adjusted to the above range.

[0108] The above L * value, a * Value and b * The values ​​represent the rust-preventive coating obtained by spraying the rust-preventive coating composition onto degreased SPCC-SB (cold-rolled steel sheet with bright finish as defined in JIS G 3141:2017) to a dry film thickness of 60 μm, and then drying it at 23°C for one week. * value, a * Value and b * The values ​​can be obtained using a spectrophotometer (e.g., Konica Minolta CR-400). The rust-preventive paint composition may contain a white pigment (typically titanium dioxide).

[0109] (Painted items) A painted article according to one embodiment of the present disclosure comprises a steel material having rust on its surface and a rust-preventive coating film formed on the steel material with the rust-preventive coating composition of the present disclosure.

[0110] ·Steel material Steel materials may be primary steel products formed and / or processed by rolling (rolled steel products), forging (forged steel products), casting (cast steel products), etc. Typical examples of steel materials include sheet steel (steel plates). Specific examples of steel plates include cold-rolled steel plates, hot-rolled steel plates, electro-galvanized steel plates, hot-dip galvanized steel plates, zinc-aluminum alloy plated steel plates, zinc-iron alloy plated steel plates, zinc-magnesium alloy plated steel plates, zinc-aluminum-magnesium alloy plated steel plates, aluminum plated steel plates, aluminum-silicon alloy plated steel plates, and tin plated steel plates. Steel materials may also be secondary steel products such as painted color steel plates and coated steel plates with a resin layer.

[0111] Examples of objects to be coated include ships, vehicles (e.g., railway cars, heavy vehicles), aircraft, bridges, offshore structures, plants, tanks (e.g., oil tanks), pipes, steel pipes, cast iron pipes, steel structures, and buildings.

[0112] The steel material may have been blast-treated, rust-preventively painted, coated with a shop primer, or coated with an organic or inorganic zinc-rich primer. The steel plate may have a previous coating (a coating other than the rust-preventive coating that was formed before the above-mentioned rust-preventive coating was formed).

[0113] The rust-preventive paint composition having the above-described shear viscosity is particularly suitable for steel materials having surface irregularities due to rust. Since the rust-preventive paint composition has appropriate viscosity during both application and leveling, the rust-preventive coating can cover the recesses and protrusions formed by rust on the surface of the steel material, i.e., the entire rust on the surface of the steel material.

[0114] When a rust-preventive coating covers rust on the surface of steel, it means that rust is not directly visible when the painted item is viewed from above.

[0115] The thickness of the rust is not particularly limited, but may be between 10 μm and 200 μm. Even if the rust thickness is 10 μm or more, the rust-preventive coating can be formed to cover the entire rust on the surface of the steel material. From the viewpoint of rust prevention, the rust thickness may be 200 μm or less. The rust thickness may be 100 μm or less, or 50 μm or less. The rust-preventive coating composition of this disclosure exhibits high rust prevention even for steel materials with rust 200 μm thick.

[0116] The thickness of rust is measured using an electromagnetic induction type thickness gauge (for example, Kett's "LZ-370") as follows: First, zero-point calibration is performed on a portion of the rusted steel material from which the rust has been thoroughly removed. Then, the thickness is measured at five arbitrary locations where rust is present, and the average value is taken as the rust thickness. If steel material before rusting is available, zero-point calibration may be performed at any point on the steel material before rusting.

[0117] Rust is a corrosive substance produced by the oxidation-reduction reaction of metal atoms contained in steel. Rust includes corrosion products such as precipitated films, oxide films, hydroxide films, and oxyhydroxide films. Rust usually exists as a film on the surface of steel, and may also exist in the form of pitting corrosion. The surface of steel refers to, for example, the surface exposed to the outside air, and may include parts that cannot be seen or touched. The main components of rust include iron compounds such as iron oxide, iron hydroxide, iron oxyhydroxide, and iron carbonate. Rust may also contain salts consisting of non-ferrous metal cations such as zinc and anions such as phosphoric acid, molybdate ions, and sulfate ions. Resin layers or coatings may remain on the surface of the rust.

[0118] Another embodiment of the painted article of this disclosure comprises a steel material having salt on its surface, and a rust-preventive coating film formed on the steel material with the rust-preventive coating composition of this disclosure. The steel material may have the above-mentioned rust along with the salt. Details of the steel material are the same as above.

[0119] The salt concentration on the surface of the steel material is not particularly limited. For example, the salt concentration on the surface of the steel material may be 5 mg / m³. 2 The above is acceptable, or 30 mg / m² 2 The above is acceptable, or 50 mg / m² 2 The above is sufficient; 75 mg / m² 2 The above is sufficient, and 100 mg / m² 2 The above is sufficient, and 200 mg / m² 2 The above is sufficient. The rust-preventive coating composition of this disclosure exhibits high rust prevention even against steel materials with high concentrations of salt.

[0120] The salt concentration on the surface of the steel material is obtained as follows: First, pure water is injected into the measuring cell in which the object to be measured is fixed. After injection, the stirring function of the device is started. This start of stirring is taken as the measurement start point. The electrical conductivity of the water is measured one minute after the start of measurement. The value obtained by converting this measurement to the water-soluble salt concentration or sodium chloride concentration is taken as the salt concentration (mg / m³) on the surface of the steel material. 2 The salinity can be obtained, for example, using a surface salinity meter manufactured by Sanko Electronics Laboratory, named "SNA-3000".

[0121] • Anti-corrosion coating The rust-preventive coating composition forms a rust-preventive coating film with excellent rust-preventive properties. The thickness of the rust-preventive coating film is not particularly limited and can be set appropriately depending on the type of object to be coated, its application, etc. The dry film thickness of the rust-preventive coating film is, for example, 30 μm to 300 μm. The rust-preventive coating composition may be applied multiple times to form a layered rust-preventive coating film.

[0122] The dry film thickness of the rust-preventive coating may be 60 μm or more, or 120 μm or more. The dry film thickness of the rust-preventive coating may be 240 μm or less, or 180 μm or less.

[0123] The dry film thickness of the rust-preventive coating is measured using an electromagnetic induction type film thickness gauge (for example, Kett's "LZ-370") as follows: First, zero-point calibration is performed at an arbitrary point on the steel material before rust occurs, or at a part of the painted steel material where the rust-preventive coating has been sufficiently removed. Then, the thickness is measured at five arbitrary points on the rust-preventive coating, and the average value is subtracted from the rust thickness obtained by the above method to obtain the dry film thickness of the rust-preventive coating.

[0124] The dry film thickness may also be theoretically calculated using the following formula, based on information regarding the application amount, specific gravity, solid content, and specific gravity of volatile components of the rust-preventive coating composition.

[0125] y=x×[(1 / dt)-{(100-NV) / (100×ds)}] x: Application amount [g / m 2 ] y: Dry film thickness [μm] z: Wet film thickness [μm] dt: Specific gravity of paint [g / cm³] 3 ] NV: Heat residue of paint [wt%] ds: Specific gravity of volatile components (solvent content in the paint) [g / cm³] 3 ]

[0126] Furthermore, the thickness of the rust-preventive coating before drying (wet film thickness) z (μm) can be calculated using the formula z = x / dt.

[0127] Other coatings Other coatings may be formed on top of the rust-preventive coating. These other coatings may be formed, for example, by so-called topcoats and / or functional coatings.

[0128] Examples of topcoat paint compositions include oil-based paints, long-oil phthalic acid resin paints, silicone alkyd resin paints, phenolic resin paints, chlorinated rubber resin paints, epoxy resin paints, modified epoxy resin paints, tar epoxy resin paints, vinyl chloride resin paints, polyurethane resin paints, fluororesin paints, and silicone-modified resin paints. Examples of functional paints include photocatalytic paints that exhibit a self-cleaning function against pollutants, and antifouling paints that prevent the adhesion of marine organisms.

[0129] (Method of manufacturing painted articles) The painted articles of this disclosure are manufactured by a method comprising applying the rust-preventive coating composition of this disclosure to steel having rust or salt on its surface.

[0130] • Painting method The painting method is not particularly limited. The rust-preventive paint composition is applied to the steel material by common methods such as brushes, rollers, or sprays.

[0131] The rust-preventive coating composition can be air-dried. Air-drying may take place at room temperature (23°C ± 3°C) for 2 hours or more, 24 hours or more, or even 1 week or more. [Examples]

[0132] The embodiment will be described in more detail below using examples, but the embodiment is not limited in any way by these examples. In the examples, "parts" and "%" are based on mass unless otherwise specified.

[0133] [Manufacturing Example 1] Preparation of epoxy resin (a) In a 2L reactor equipped with a thermometer, stirrer, and condenser, along with a water separator, 250g of p-tert-butylphenol novolac resin (product name: Hitanol #1133, manufactured by Hitachi Chemical Co., Ltd.), 250g of octylphenol novolac resin (product name: Hitanol #1501, manufactured by Hitachi Chemical Co., Ltd.), and 1440g of epichlorohydrin were charged and stirred to form a homogeneous solution. Next, 268g of 48% by mass sodium hydroxide was added dropwise at 60-110°C over 2 hours. During this time, the water generated in the system was removed from the system by azeotropic reaction with the epichlorohydrin using the water separator, while the epichlorohydrin was refluxed in the system. After the dropwise addition was complete, the system was aged at 100-120°C for 2 hours, and the reaction was terminated when the theoretical amount of water had been drained.

[0134] The obtained epoxy compound was treated with an epichlorohydrin solution to which 150 g of xylene was added and washed with a large amount of water. After removing the generated sodium chloride and excess sodium hydroxide, the mixture was neutralized with a 3% by mass aqueous phosphoric acid solution. Then, the epichlorohydrin and xylene were removed under reduced pressure, and 460 g of a high-boiling point paraffinic solvent (trade name: Swazole 310, manufactured by Cosmo Oil Co., Ltd.) was added to obtain liquid epoxy resin (a) (novolac-type epoxy resin). The weight-average molecular weight of epoxy resin (a) was 8500, the epoxy equivalent was 1010 g / eq, and the solids content was 60% by mass.

[0135] [Examples 1-108, Comparative Examples 1-47] The main component and hardener were prepared according to the formulations shown in Tables 1 to 13. The main component and hardener were mixed to prepare the rust-preventive paint composition. Unless otherwise specified, the amounts in Tables 1 to 13 represent the mass percentage relative to the solid content of the rust-preventive paint composition.

[0136] The details of each component shown in Tables 1-13 are as follows: Polyamine (b) • Alicyclic polyamine (b-1): 1,3-bis(aminomethyl)cyclohexane, manufactured by Tokyo Chemical Industry Co., Ltd., active hydrogen equivalent 34.2 g / eq, weight-average molecular weight 142.24 • Non-alicyclic polyamine (b-2): m-xylylenediamine, manufactured by Tokyo Chemical Industry Co., Ltd., active hydrogen equivalent 35.5 g / eq, weight-average molecular weight 136.19

[0137] Alkylphenol ·o-tert-butylphenol Thickening agent • Product name "F-9050", manufactured by Kusumoto Chemical Co., Ltd., a mixture of aliphatic amide wax and oxidized polyolefin wax. defoaming agent • Product name: "Disparon 1958", manufactured by Kusumoto Kasei Co., Ltd. Weak solvent • Product name: Solvesso 100, manufactured by Exxon Mobil.

[0138] Metal sulfate (c-1) The amount of water that dissolves in 100g of water at 5°C is shown in parentheses. Aluminum sulfate (32.2g) Nickel sulfate hexahydrate (39.1g) Magnesium sulfate (25.4g)

[0139] Zinc compound (c-2) The values ​​in parentheses indicate the amount of solution that dissolves in 100g of water at pH 4.0 and pH 7.0 at 20°C. Zinc carbonate (pH 4.0: >8.13g, pH 7.0: 0.000470g) Zinc oxide (pH 4.0: >12.5g, pH 7.0: 0.000394g) Zinc hydroxide (pH 4.0: >13.1g, pH 7.0: 0.000425g)

[0140] Alkaline earth metal compounds (c-3) The amount of water that dissolves in 100g of water at 20°C is shown in parentheses. Calcium oxide (0.112g) Barium oxide (3.48g) Calcium hydroxide (0.173g) Barium hydroxide (3.89g)

[0141] The average particle size of each type of powder (c) was 0.1 to 40 μm.

[0142] [Measurement method] (i) High shear viscosity and low shear viscosity Using the product name "Solvesso 100," the solid content concentration (NV) of the rust-preventive paint composition was adjusted (diluted) to 69.0% by mass to obtain a sample for shear viscosity measurement. Under conditions of 25°C, the viscosity (Pa·s) was measured using a rheometer (Anton Paar, product name "MCR-302") after 1 minute had elapsed since the start of shear stress application at a shear rate of 1000 (1 / s), and after 1 minute had elapsed since the start of shear stress application at a shear rate of 0.1 (1 / s).

[0143] (ii) Thickness of rust on the surface of the steel plate Using an electromagnetic induction type film thickness gauge (manufactured by Kett, product name "LZ-370"), zero-point calibration was performed at an arbitrary point on a TP Giken SS400 grid-blasted steel sheet before rust occurred. Then, the thickness was measured at five arbitrary points where rust was present, and the average value was taken as the rust thickness.

[0144] (iii) Thickness of the rust-preventive coating An electromagnetic induction type film thickness gauge (Kett Corporation, product name "LZ-370") was used to perform zero-point calibration at arbitrary points on TP Giken's SS400 grid-blasted steel plate before rust formation. After painting, the thickness of the rust-preventive coating was measured at five arbitrary points, and the average value minus the rust thickness obtained using the method described above was used as the dry film thickness of the rust-preventive coating.

[0145] [evaluation] The rust-preventive coating compositions were evaluated using the following method. The evaluation results are shown in Tables 1 to 13.

[0146] (1) Rust prevention A (Rust prevention of steel plates with rust) TP Giken's SS400 grid-blasted steel sheets were exposed to the coastal area of ​​Tamano City, Okayama Prefecture for three months to obtain rusted steel sheets. Four types of surface preparation treatments were applied to the rusted sheets to obtain rusted sheets with a thickness of 30 μm. Next, the salt concentration on the surface of the steel sheets was adjusted by washing with deionized water or with a sodium chloride aqueous solution. As a result, seven types with different surface salt concentrations (5 ± 5 mg / m²) were obtained. 2 , 30±5 mg / m² 2 , 50±5 mg / m² 2 , 100±30mg / m² 2 , 200±30mg / m² 2 , 500±100mg / m² 2 , 1000±200mg / m² 2 A test plate was obtained. The surface salinity was measured using a surface salinity meter SNA-3000 manufactured by Sanko Electronics Laboratory, and the salinity (mg / m³) was measured 1 minute after the start of measurement. 2 The value of ) was adopted.

[0147] After spraying each test plate with the rust-preventive coating composition, the plates were dried at 23°C for one week to produce coated plates with a rust-preventive coating film 60 μm thick.

[0148] The obtained painted boards (75 mm x 150 mm) were subjected to a combined cyclic corrosion test in accordance with Cycle A (CCT) of the cyclic corrosion test method specified in JIS K5600-7-9:2006. Specifically, a 150-cycle accelerated corrosion test was performed using a combined cyclic corrosion tester (Suga Test Instruments Co., Ltd., model CCT-1). The number of pitted rust spots that occurred after the test was evaluated. If all seven types of test boards were at level 7 or higher, they were considered to have high corrosion resistance.

[0149] (Evaluation Criteria) 10:0 pieces 9: Less than 10 8: 10 or more, less than 20 7: 20 to less than 50 items 6: 50 to less than 100 items 5: 100 or more but less than 200 4: 200 or more, less than 400 3: 400 or more, less than 600 2: 600 or more, less than 800 1:800 pieces or more

[0150] (2) Rust prevention B (rust prevention of steel plates containing salt) TP Giken's SS400 grid-blasted steel plates were exposed to the coastal area of ​​Tamano City, Okayama Prefecture for 12 months to induce rust formation. Partial rust removal was performed using nonwoven abrasive material (product name "Magiclon," manufactured by Sankyo Rikagaku Co., Ltd.) as needed, resulting in the preparation of five types of steel plates with rust thicknesses of 30±2μm, 40±5μm, 60±5μm, 80±5μm, and 100±10μm. Next, the salt concentration on the steel plate surface was adjusted to 50±5mg / m² using a sodium chloride aqueous solution. 2 I adjusted it to that.

[0151] Except for using the steel plates described above, painted panels were prepared in the same manner as for rust prevention level A, and corrosion acceleration tests and evaluations were conducted. If all five types of test panels achieve level 7 or higher, they possess high rust prevention properties.

[0152] (3) Hue A rust-preventive coating composition was spray-applied to degreased SPCC-SB (cold-rolled steel sheet with a bright finish as specified in JIS G 3141:2017), and then dried at 23°C for one week to produce a coated board with a rust-preventive coating film 60 μm thick. The L of the obtained painted board * a * b * L in color systems * value, a * Value and b * The values ​​were measured using a spectrophotometer (Konica Minolta CR-400). A rating of A means the rust-preventive paint composition is white to light-colored, indicating a high degree of freedom in color design. A rating of B means the rust-preventive paint composition is colored.

[0153] (Evaluation Criteria) A:L * ≥70, -5.0 ≤ a * ,b * ≤5.0 B:L * <70, -5.0>a* ,b * a * ,b * >5.0

[0154] Table 1

[0155] Table 2

[0156] Table 3

[0157] Table 4

[0158] Table 5

[0159] Table 6

[0160] Table 7

[0161] Table 8

[0162] Table 9

[0163] Table 10

[0164] [Table 11]

[0165] [Table 12]

[0166] [Table 13]

[0167] The rust-preventive coatings formed using the rust-preventive paint compositions of Examples 1 to 108 completely covered the rust on the steel plate, and both rust prevention level A and rust prevention level B were level 7 or higher. In particular, at 100 mg / m² 2 It exhibited high rust prevention properties even against rusted steel plates with the above surface salt content.

[0168] Regarding examples with low zinc compound (C-2) content, the rust-preventive coatings formed using the rust-preventive coating compositions of Comparative Examples 1, 6, 36, and 41 had a content of 100 ± 30 mg / m². 2 The rust-preventive properties of the rust-covered steel plate with the above surface salt content were inferior to those of Comparative Example A. The rust-preventive coating film formed using the rust-preventive coating composition of Comparative Example 11 was 200±30 mg / m². 2 The rust prevention performance against rusted steel plates with the above surface salt content was inferior to that of A.

[0169] Regarding examples with a high content of zinc compound (C-2), the rust-preventive coating formed using the rust-preventive coating composition of Comparative Example 2 had a content of 100 ± 30 mg / m². 2 The rust-preventive properties of the rust-covered steel plates with surface salt concentrations above were inferior to those of A. The rust-preventive coatings formed using the rust-preventive coating compositions of Comparative Examples 7, 12, 37, and 42 had a rust-preventive coating density of 200 ± 30 mg / m². 2 The rust prevention performance of this material was inferior to that of rusted steel plates with the above surface salt concentrations (compared to A).

[0170] Regarding examples that do not contain zinc compound (c-2) and use zinc powder, the rust-preventive coating formed using the rust-preventive coating compositions of Comparative Examples 3-5, 38-40, and 43 had a concentration of 100 ± 30 mg / m². 2 The rust-preventive properties of the rust-covered steel plates with surface salt concentrations above were inferior to those of A. The rust-preventive coatings formed using the rust-preventive coating compositions of Comparative Examples 8-10, 13-15, 30, and 44 had a surface salt concentration of 200 ± 30 mg / m². 2 The rust prevention performance against rusted steel plates with the above surface salt concentration was inferior to that of A. Comparative Example 45 showed that the rust-preventive coating film formed using the rust-preventive paint composition was 50±5 mg / m². 2 The rust prevention performance against rusted steel plates with the above surface salt content was inferior to that of A.

[0171] Comparative Examples 5, 40, and 45, which had particularly high zinc powder content, also exhibited poor rust prevention (C) on steel plates with rust thicknesses of 60±5 μm or more. Comparative Examples 4, 10, 15, 30, and 44 showed poor rust prevention (C) on steel plates with rust thicknesses of 80±5 μm or more. Comparative Examples 9, 14, and 39 showed poor rust prevention (C) on steel plates with rust thicknesses of 100±10 μm or more. This is thought to be due to the low shear viscosity of the paint being less than 50 Pa·s, which resulted in thinner paint film thickness on the raised areas of rust. Furthermore, these examples did not meet the target hue standard.

[0172] Regarding examples that do not contain zinc compounds (C-2) but contain alkaline earth metal compounds (C-3), Comparative Examples 16, 18-21, 23-26, 28, and 29 have a concentration of 100 ± 30 mg / m². 2 The rust-preventive properties A of the rusted steel plates with the above surface salt concentrations were inferior. Comparative Examples 17, 22, and 27 had a salt concentration of 200 ± 30 mg / m². 2 The rust-resistant steel plates with the above surface salt concentrations exhibited poor rust prevention properties (A).

[0173] Comparative Examples 31-35, which do not contain metal sulfate (C-1) and contain only zinc compound (C-2), have a concentration of 100±30 mg / m². 2 The rust-resistant steel plates with the above surface salt concentrations exhibited poor rust prevention properties (A).

[0174] Comparative Examples 46 and 47, which had a high content of metal sulfate (c-1), showed a concentration of 100 ± 30 mg / m². 2The rust prevention performance of these coatings was inferior to that of coating A against rusted steel plates with surface salt concentrations exceeding 60±5 μm. Furthermore, their rust prevention performance was also inferior to that of coating B against steel plates with rust thicknesses of 60±5 μm or more. This is thought to be because the zinc compound dissolved rapidly due to the excessive amount of metal sulfate present, reducing the barrier function of the coating film.

[0175] The present invention provides the following embodiments. [1] epoxy resin (a) and Polyamine (b) and, Powder (c) and, A rust-preventive paint composition comprising a thickening agent (d), The aforementioned powder (c) is A metal sulfate (c-1) whose solubility in 100g of water at 5℃ is 0.1g or more, A zinc compound (c-2) having a solubility of less than 0.03 g in 100 g of water at pH 7.0 and 20°C, and a solubility of 0.03 g or more in 100 g of water at pH 4.0 and 20°C, is included. The content of the metal sulfate (c-1) is 0.2% by mass or more and 70% by mass or less, based on 100 parts by mass of the resin solids of the rust-preventive coating composition. The content of the zinc compound (c-2) is 10% by mass or more and 200% by mass or less based on 100 parts by mass of the resin solids content of the rust-preventive paint composition. [2] The rust-preventive paint composition according to [1] above, wherein the mass-based ratio (c-1 / c-2) of the content of the metal sulfate (c-1) to the content of the zinc compound (c-2) is 0.08 / 99.92 to 90.00 / 10.00. [3] A rust-preventive coating composition according to [1] or [2] above, for use with steel materials having rust on their surface. [4] A rust-preventive coating composition for steel materials having salt on their surface, as described in any of the above [1] to [3]. [5] The rust-preventive paint composition according to any of the above [1] to [4], wherein the metal sulfate (c-1) is a salt of a polyvalent metal cation and a sulfate ion. [6] The rust-preventive coating composition according to any of the above [1] to [5], wherein the metal sulfate (c-1) comprises at least one selected from the group consisting of nickel sulfate, aluminum sulfate, magnesium sulfate, zinc sulfate, cobalt sulfate, chromium sulfate, copper sulfate, titanium sulfate, tin sulfate, zirconium sulfate, vanadium sulfate, and manganese sulfate. [7] The aforementioned zinc compound (c-2) comprises at least one selected from the group consisting of zinc oxide, zinc hydroxide, and zinc carbonate, wherein the rust-preventive coating composition is any of the above [1] to [6]. [8] The rust-preventive coating composition according to any of the above [1] to [7], wherein the powder (c) further comprises an alkaline earth metal compound (c-3), which is at least one of an alkaline earth metal oxide and an alkaline earth metal hydroxide. [9] The rust-preventive paint composition according to [8] above, wherein the content of the alkaline earth metal compound (c-3) is 0.15% by mass or more and 40% by mass or less based on 100 parts by mass of the resin solids of the rust-preventive paint composition.

[10] The rust-preventive coating composition according to [8] or [9] above, wherein the alkaline earth metal compound (c-3) comprises at least one selected from the group consisting of calcium oxide, calcium hydroxide, barium oxide, and barium hydroxide.

[11] A rust-preventive paint composition according to any of the above [1] to

[10] , wherein, under conditions of a solid content concentration of 69% by mass and a temperature of 25°C, the viscosity measured using a rheometer is 0.1 Pa·s or more and 1.2 Pa·s or less after 1 minute when shear stress is applied at a shear rate of 1000 (1 / s), and the viscosity measured at 40 Pa·s or more and 500 Pa·s or less after 1 minute when shear stress is applied at a shear rate of 0.1 (1 / s).

[12] Steel material with rust on the surface, A painted article comprising a rust-preventive coating film formed on the steel material with any of the rust-preventive coating compositions [1] to

[11] above.

[13] The painted article according to

[12] above, wherein the thickness of the rust on the surface of the steel material is 10 μm or more and 200 μm or less.

[14] The painted article according to

[12] or

[13] , wherein the rust-preventive coating covers the rust on the surface of the steel material.

[15] Steel material having salt on its surface, A painted article comprising a rust-preventive coating film formed on the steel material with any of the rust-preventive coating compositions [1] to

[11] above.

[16] A method for manufacturing a painted article, comprising applying one of the rust-preventive paint compositions [1] to

[11] above onto a steel material having rust on its surface.

[17] A method for manufacturing a painted article, comprising applying one of the rust-preventive paint compositions [1] to

[11] above onto a steel material having salt on its surface. [Industrial applicability]

[0176] The present invention provides a rust-preventive coating composition that can impart excellent rust prevention properties even to steel materials with residual rust or salt. The rust-preventive coating composition according to the present invention is particularly suitable for priming steel materials used in large structures such as plants, bridges, transmission towers, and buildings.

Claims

1. epoxy resin (a) and Polyamine (b) and, Powder (c) and, A rust-preventive paint composition comprising a thickening agent (d), The aforementioned powder (c) is A metal sulfate (c-1) whose solubility in 100 g of water at 5°C is 0.1 g or more, The present invention contains a zinc compound (c-2) whose solubility in 100g of water at pH 7.0 and 20°C is less than 0.03g, and whose solubility in 100g of water at pH 4.0 and 20°C is 0.03g or more, The content of the metal sulfate (c-1) is 0.2% by mass or more and 70% by mass or less, based on 100 parts by mass of the resin solids of the rust-preventive coating composition. The content of the zinc compound (c-2) is 10% by mass or more and 200% by mass or less based on 100 parts by mass of the resin solids content of the rust-preventive paint composition.

2. The rust-preventive coating composition according to claim 1, wherein the mass-based ratio (c-1 / c-2) of the content of the metal sulfate (c-1) to the content of the zinc compound (c-2) is 0.08 / 99.92 to 90.00 / 10.

00.

3. The rust-preventive coating composition according to claim 1, for use with steel materials having rust on their surface.

4. The rust-preventive coating composition according to claim 1, for use with steel materials having salt on their surface.

5. The rust-preventive coating composition according to claim 1, wherein the metal sulfate (c-1) is a salt of a polyvalent metal cation and a sulfate ion.

6. The rust-preventive coating composition according to claim 1, wherein the metal sulfate (c-1) comprises at least one selected from the group consisting of nickel sulfate, aluminum sulfate, magnesium sulfate, zinc sulfate, cobalt sulfate, chromium sulfate, copper sulfate, titanium sulfate, tin sulfate, zirconium sulfate, vanadium sulfate, and manganese sulfate.

7. The rust-preventive coating composition according to claim 1, wherein the zinc compound (c-2) comprises at least one selected from the group consisting of zinc oxide, zinc hydroxide, and zinc carbonate.

8. The rust-preventive coating composition according to claim 1, wherein the powder (c) further comprises an alkaline earth metal compound (c-3) which is at least one of an alkaline earth metal oxide and an alkaline earth metal hydroxide.

9. The rust-preventive paint composition according to claim 8, wherein the content of the alkaline earth metal compound (c-3) is 0.15% by mass or more and 40% by mass or less with respect to 100 parts by mass of the resin solids content of the rust-preventive paint composition.

10. The rust-preventive coating composition according to claim 8, wherein the alkaline earth metal compound (c-3) comprises at least one selected from the group consisting of calcium oxide, calcium hydroxide, barium oxide, and barium hydroxide.

11. The rust-preventive coating composition according to claim 1, wherein, under conditions of a solid content concentration of 69% by mass and a temperature of 25°C, the viscosity measured using a rheometer is 0.1 Pa·s or more and 1.2 Pa·s or less after 1 minute when shear stress is applied at a shear rate of 1000 (1 / s), and the viscosity measured at 40 Pa·s or more and 500 Pa·s or less after 1 minute when shear stress is applied at a shear rate of 0.1 (1 / s).

12. Steel material with rust on the surface, A painted article comprising a rust-preventive coating film formed on the steel material with a rust-preventive coating composition according to any one of claims 1 to 11.

13. The painted article according to claim 12, wherein the thickness of the rust on the surface of the steel material is 10 μm or more and 200 μm or less.

14. The painted article according to claim 13, wherein the rust-preventive coating covers the rust on the surface of the steel material.

15. Steel material having salt on its surface, A painted article comprising a rust-preventive coating film formed on the steel material with a rust-preventive coating composition according to any one of claims 1 to 11.

16. A method for manufacturing a painted article, comprising applying a rust-preventive paint composition according to any one of claims 1 to 11 to a steel material having rust on its surface.

17. A method for manufacturing a painted article, comprising applying a rust-preventive paint composition according to any one of claims 1 to 11 to a steel material having salt on its surface.

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