Anticorrosive coating composition

Abstract

This anticorrosive coating composition comprises an epoxy resin (a), a polyamine (b), and powder (c), wherein: the powder (c) contains a metal sulfate (c-1) with a dissolution amount of 0.1 g or more with respect to 100 g of water at 5°C, and a white zinc compound (c-2) having a dissolution amount of 0.005 g or less with respect to 100 g of water at 20°C at a pH of more than 5.0 and having a dissolution amount of 0.05 g or more with respect to 100 g of water at 20°C at a pH of 5.0 or less; the content of the metal sulfate (c-1) is 0.05%-20% by mass of the solid content of the anticorrosive coating composition; and the content of the zinc compound (c-2) is 5%-60% by mass of the solid content of the anticorrosive coating composition.

Description

Anticorrosion coating composition

[0001] The present invention relates to an anticorrosion coating composition.

[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.

[0003] Japanese Patent Application Laid-Open No. 2021-167379

[0004] Paints containing zinc and zinc alloys have high corrosion resistance, but zinc and zinc alloys are generally not white, limiting the design of the finish.

[0005] An object of the present invention is to provide an anticorrosion coating composition which has excellent anticorrosion properties and allows for a high degree of freedom in color design.

[0006] The present invention provides the following aspects: [1] An anticorrosion coating composition comprising an epoxy resin (a), a polyamine (b), and a powder (c), wherein the powder (c) comprises: a metal sulfate (c-1) having a solubility of 0.1 g or more in 100 g of water at 5°C, and a white zinc compound (c-2) having a solubility of 0.005 g or less in 100 g of water at a pH greater than 5.0 and at 20°C, and a solubility of 0.05 g or more in 100 g of water at a pH of 5.0 or less and at 20°C, wherein the content of the metal sulfate (c-1) is 0.05% by mass or more and 20% by mass or less of the solid content of the anticorrosion coating composition, and the content of the zinc compound (c-2) is 5% by mass or more and 60% by mass or less of the solid content of the anticorrosion coating composition. [2] The anticorrosion coating composition of [1] above, wherein the powder (c) further contains an alkaline earth metal compound (c-3) which is at least one of an alkaline earth metal oxide and an alkaline earth metal hydroxide. [3] The anticorrosion coating composition of [2] above, wherein the content of the alkaline earth metal compound (c-3) is 0.05 mass% or more and 20 mass% or less of the solid content of the anticorrosion coating composition. [4] The anticorrosion coating composition of [2] or [3] above, wherein the alkaline earth metal compound (c-3) contains at least one selected from the group consisting of calcium oxide, calcium hydroxide, barium oxide, and barium hydroxide. [5] The anticorrosion coating composition of any of [1] to [4] above, wherein the metal sulfate (c-1) is a salt of a polyvalent metal cation and a sulfate ion. [6] The anticorrosion coating composition of any one of [1] to [5] 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 anticorrosion coating composition of any one of [1] to [6] above, wherein the zinc compound (c-2) comprises at least one selected from the group consisting of zinc oxide, zinc hydroxide, and zinc carbonate.

[0007] According to the present invention, there is provided an anticorrosion coating composition which has excellent anticorrosion properties and allows for a high degree of freedom in color design.

[0008] The anticorrosion coating composition of the present disclosure comprises an epoxy resin (a), a polyamine (b), and a powder (c), wherein the powder (c) comprises a metal sulfate (c-1) having a solubility of 0.1 g or more in 100 g of water at 5° C., and a white zinc compound (c-2) having a solubility of 0.005 g or less in 100 g of water at a pH greater than 5.0 and at 20° C., and a solubility of 0.05 g or more in 100 g of water at a pH of 5.0 or less and at 20° C.

[0009] The content of the metal sulfate (c-1) is from 0.05 to 20% by mass of the solid content of the anticorrosion coating composition, and the content of the zinc compound (c-2) is from 5 to 60% by mass of the solid content of the anticorrosion coating composition.

[0010] The metal sulfate (c-1) dissolves in water, eluting metal ions and sulfate ions. The zinc compound (c-2) dissolves due to the action of sulfate ions and the generation of hydrogen ions through hydrolysis of the metal ions, generating zinc ions. The zinc ions react with chloride ions (contained in airborne salt, rainwater, or rust on the surface of the substrate, which promote corrosion) and trap the chloride ions. The reaction between zinc ions and chloride ions generates, for example, basic zinc chloride. Reaction products such as basic zinc chloride form a water-stable coating (hereinafter referred to as the "anti-corrosion layer") within the coating. The anti-corrosion layer provides high corrosion protection.

[0011] Anticorrosion coating compositions are usually used as undercoats (primers). In recent years, due to the diversification of applications and preferences and the pursuit of originality, the designs required for finish coatings have become more diverse. Because the zinc compound (c-2) is white, the finish coating can be designed to have a desired design (particularly, a desired hue). The ability to select the design of the finish coating without being limited by the color of the primer is one of the important appealing points to consumers.

[0012] The L of a 60 μm thick primer coating formed from the anticorrosion coating composition of the present disclosure ＊ a ＊ b ＊ L in color system ＊ Value, a ＊ value and b ＊ The value is L ＊≧70, 0≦a ＊ ≦5.0, and 0≦b ＊ This primer coating film has a hue that can be used for a light-colored top coat. In other words, there is a high degree of freedom in color design, and the finish coating can be designed as desired.

[0013] The above L ＊ Value, a ＊ value and b ＊ The values ​​are the values ​​of the primer coating film obtained by spraying the anticorrosion coating composition onto degreased SPCC-SB (cold rolled steel plate with a bright finish as specified 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 value can be obtained by a spectrophotometer (for example, CR-400 manufactured by Konica Minolta, Inc.) The anticorrosion coating composition may contain a white pigment (typically, titanium oxide).

[0014] (Anti-corrosion coating composition) The anti-corrosion coating composition may be a two-component type consisting of a base agent containing an epoxy resin (a) and a curing agent containing a polyamine (b). The powder (c) may be contained in the base agent, in the curing agent, or in both. The powder (c) may be contained in the base agent.

[0015] Hereinafter, the epoxy equivalent is determined based on the mass of the solid content in accordance with JIS K 7236:2001.

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

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

[0018] The solid content of the anticorrosion coating composition is the total content of the coating composition excluding volatile components (typically, solvents). The solid content concentration of the anticorrosion coating composition can be calculated from the residue when the coating composition is heated at 140°C in accordance with JIS K 5601-1-2 Heat Residue Measurement Method.

[0019] The resin solid content of the anticorrosion coating composition is the solid content of the epoxy resin (a), polyamine (b) and other resin components contained in the anticorrosion coating composition.

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

[0021] The epoxy resin (a) is not particularly limited. Examples of the 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 may be used alone or in combination of two or more. The epoxy resin (a) may be a modified product of the above-mentioned epoxy resin. In terms of moisture resistance and toughness, the epoxy resin may be an aromatic epoxy resin or a novolac-type epoxy resin.

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

[0023] Examples of novolac epoxy resins include phenol novolac, cresol novolac, and bisphenol A novolac. These may be used alone or in combination of two or more.

[0024] Examples of the biphenyl-, naphthalene-, and dicyclopentadiene-type resins include resins in which one or more glycidyl ether groups are substituted at any position of biphenyl, naphthalene, or dicyclopentadiene. These may be used alone or in combination of two or more.

[0025] The solid content of the epoxy resin (a) is, for example, 15% by mass or more and 60% by mass or less of the solid content of the anticorrosion coating composition. When the content of the epoxy resin (a) is 15% by mass or more, curability can be improved. When the content of the epoxy resin (a) is 60% by mass or less, the relative proportion of the pigment in the coating film increases, thereby improving hiding power. The content of the epoxy resin (a) may be 20% by mass or more, or may be 25% by mass or more. The content of the epoxy resin (a) may be 50% by mass or less, or may be 40% by mass or less.

[0026] The weight average molecular weight of the epoxy resin (a) is not particularly limited. The weight average molecular weight of the epoxy resin (a) may be 6,500 or more and 10,000 or less, in order to enhance curability (particularly curability at low temperatures of 5°C or less). The weight average molecular weight of the epoxy resin (a) may be 8,500 or more. The weight average molecular weight of the epoxy resin (a) may be 10,000 or less.

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

[0028] Commercially available novolac epoxy resins (a) include, for example, EPICLON 5970-60 (phenol novolac epoxy resin, weight average molecular weight 9500, solid content 60% by mass, epoxy equivalent 1000 g / eq or more, manufactured by DIC Corporation). Commercially available bisphenol A epoxy resins (a) include, for example, EPICLON 1040-70X (bisphenol A epoxy resin, solid content 70% by mass, epoxy equivalent 1300 g / eq, manufactured by DIC Corporation).

[0029] Polyamine (b) Polyamine (b) is a curing component. Polyamine (b) undergoes a crosslinking reaction with epoxy resin (a) to form a cured coating film.

[0030] The polyamine (b) is not particularly limited. The 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) having no cyclic aliphatic hydrocarbon group to which an amino group is bonded, or may contain both. When the alicyclic polyamine (b-1) and the non-alicyclic polyamine (b-2) are used in combination, dissolution and lifting of the primer coating film is easily suppressed when another coating film is laminated on the primer coating film formed from the corrosion-protective coating composition.

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

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

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

[0034] Examples of the chain aliphatic polyamine include alkylene polyamine and polyalkylene polyamine. ２ N-R １ -NH ２ (In the formula, R １ is 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. Examples of alkylene polyamines include methylene diamine, ethylene diamine, 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 diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, and hexamethylene tetramine. These may be used alone or in combination of two or more.

[0035] Examples of the chain aliphatic polyamines include tetra(aminomethyl)methane, tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2'-aminoethylamino)propane, triethylene-bis(trimethylene)hexamine, bis(3-aminoethyl)amine, bishexamethylenetriamine [H ２ N (CH ２ ) ６ NH (CH ２ ) ６ NH ２ These may be used alone or in combination of two or more.

[0036] Examples of aromatic polyamines include bis(aminoalkyl)benzenes, bis(aminoalkyl)naphthalenes, 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'-diaminodiphenyl sulfone, 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 may be used alone or in combination of two or more.

[0037] Examples of heterocyclic polyamines include N-methylpiperazine [CH ３ -N(CH ２ CH ２ ) ２ NH], morpholine [HN(CH ２ CH ２ ) ２ O], 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 may be used alone or in combination of two or more.

[0038] The active hydrogen equivalent of the non-alicyclic polyamine (b-2) is, for example, 30 g / eq or more and 550 g / eq or less. The active hydrogen equivalent of the non-alicyclic polyamine (b-2) may be 32 g / eq or more, or 35 g / eq or more. The active hydrogen equivalent of the non-alicyclic polyamine (b-2) may be 250 g / eq or less, 100 g / eq or less, or 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 anticorrosion coating composition. When the content of polyamine (b) is 0.6% by mass or more, curability can be improved. When the content of polyamine (b) is 15% by mass or less, barrier properties can be improved. The content of polyamine (b) may be 0.8% by mass or more, or 0.9% by mass or more. The 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 the 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 anticorrosion coating composition. When the content of the alicyclic polyamine (b-1) is 0.5% by mass or more, curability can be improved, particularly at low temperatures. When the content of the alicyclic polyamine (b-1) is 10% by mass or less, the tackiness of the resulting coating film can be reduced and the treadability can be improved. The content of the 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 content of the 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. The treadability refers to the ability of a coating film to be less susceptible to shoe marks and to peeling when a worker walks on the coating film.

[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 anticorrosion coating composition. When the content of the non-alicyclic polyamine (b-2) is 10% by mass or less, the tackiness of the resulting coating film at low temperatures is reduced, and the treadability may be improved. The content of the non-alicyclic polyamine (b-2) may be 0.1% by mass or more, or 0.15% by mass or more. The content of the 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 an alkylphenol, which further improves curability (particularly 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 may be used alone or in combination of two or more. The number of carbon atoms in the alkyl group of the alkylphenol is, for example, 1 to 10. The number of carbon atoms may be 5 or less.

[0044] The solid content of the alkylphenol is, for example, 0.05% by mass or more and 5.0% by mass or less of the solid content of the anticorrosion coating composition. The content of the alkylphenol may be 0.1% by mass or more, or 0.15% by mass or more. The content of the 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) functions as a rust inhibitor. By using a specific metal sulfate (c-1) in combination with a zinc compound (c-2), excellent corrosion prevention is obtained as described above, and the degree of freedom in color design is increased.

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

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

[0048] Metal sulfate (c-1) The metal sulfate (c-1) has a dissolution amount of 0.1 g or more in 100 g of water at 5°C. The metal sulfate (c-1) is easily soluble in water even in a low-temperature environment, and therefore can promote the formation of a rust-preventive layer. The dissolution amount of the metal sulfate (c-1) may be 5.0 g or more, or may be 10.0 g or more.

[0049] The metal sulfate (c-1) may be a salt of a polyvalent metal cation and a sulfate ion. The polyvalent metal cation (hereinafter referred to as "polyvalent cation") coexists with the iron ion generated from the metal substrate, thereby forming a dense and electrochemically stable anticorrosive layer.

[0050] Examples of metals constituting the metal sulfate (c-1) include alkaline earth metals, transition metals, and post-transition metals. These metals generate polyvalent cations. These metals may be used alone 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 that exist between Groups 3 and 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), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg), rutherfordium (Rf), dubnium (Db), seaborgium (Sg), bohrium (Bh), and hassium (Hs). Post-transition metals are metal elements in the P-block of the periodic table. Specific 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 may be used alone or in combination of two or more.

[0052] Examples of the metal sulfate (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 may be used alone or in combination of two or more.

[0053] The content of the metal sulfate (c-1) is 0.05 mass% or more and 20 mass% or less of the solid content of the anticorrosion coating composition. When the content of the metal sulfate (c-1) is 0.05 mass% or more, the effects of the metal sulfate (c-1) are exerted. When the content of the metal sulfate (c-1) is 20 mass% or less, the barrier properties are further improved and the coating film properties are also improved.

[0054] The content of the metal sulfate (c-1) may be 0.1% by mass or more, 0.5% by mass or more, or 1.0% by mass or more. The content of the metal sulfate (c-1) may be 15.0% by mass or less, 12.0% by mass or less, 8.0% by mass or less, or 5.0% by mass or less.

[0055] Zinc compound (c-2) The zinc compound (c-2) provides zinc ions to the coating film. The zinc compound (c-2) dissolves in 100 g of water at 20°C at a pH greater than 5.0 in an amount of 0.005 g or less, and in 100 g of water at 20°C at a pH of 5.0 or less in an amount of 0.05 g or more. The zinc ions react with chloride ions to form a rust-preventive layer.

[0056] The zinc compound (c-2) is white. The white zinc compound (c-2) does not restrict the color of the finish coating, thereby increasing the degree of freedom in color design.

[0057] The zinc compound (c-2) has a low solubility in 100 g of water at 20°C in the range from approximately neutral to alkaline. Therefore, dissolution of the zinc compound (c-2) is suppressed in an environment where corrosion is unlikely to progress. On the other hand, in the acidic range, the zinc compound (c-2) has a high solubility in 100 g of water at 20°C. The zinc compound (c-2) dissolves and exerts its effect as the pH decreases due to the dissolution of the metal sulfate (c-1).

[0058] Examples of the zinc compound (c-2) include zinc oxide, zinc hydroxide, and zinc carbonate. These may be used alone or in combination of two or more. From the viewpoint of hiding power, zinc oxide may be included. The zinc compound (c-2) does not include metallic zinc, zinc alloys, or zinc sulfate.

[0059] The content of the zinc compound (c-2) is not particularly limited. The content of the zinc compound (c-2) is, for example, 5% by mass or more and 60% by mass or less of the solid content of the anticorrosion coating composition. When the content of the zinc compound (c-2) is 5% by mass or more, the effect of the zinc compound (c-2) is easily exhibited. When the content of the zinc compound (c-2) is 60% by mass or less, the film-forming properties are not impaired.

[0060] The content of the zinc compound (c-2) may be 10.0% by mass or more, or 15.0% by mass or more. The content of the zinc compound (c-2) may be 55.0% by mass or less, 50.0% by mass or less, 45.0% by mass or less, or 30.0% by mass or less.

[0061] Alkaline earth metal compound (c-3) The 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 a hydroxide of an alkaline earth metal. The alkaline earth metal compound (c-3) dissolves in water, eluting alkaline earth metal ions and their counter ions. The alkaline earth metal ions react with sulfate ions to form salts that are poorly soluble in water.

[0062] As described above, sulfate ions promote the formation of an anticorrosive layer, but if they act directly on the substrate, they can promote corrosion of the substrate. By blending alkaline earth metal compound (c-3) together with metal sulfate (c-1), corrosion of the substrate caused by sulfate ions is suppressed, and the occurrence of red rust is suppressed.

[0063] The amount of alkaline earth metal compound (c-3) dissolved is not particularly limited. The amount of alkaline earth metal compound (c-3) dissolved in 100 g of water at 20°C may be 0.05 g or more. The amount of alkaline earth metal compound (c-3) dissolved may be 0.1 g or more, or may be 1.0 g or more. From the viewpoint of suppressing the generation of voids due to rapid dissolution, the amount of alkaline earth metal compound (c-3) dissolved may be 5.0 g or less, or may be 4.0 g or less.

[0064] The alkaline earth metal is not particularly limited and may be any of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The alkaline earth metal may be at least one selected from the group consisting of Ca, Sr, and Ba.

[0065] Specific examples of the alkaline earth metal compound (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.

[0066] The content of the alkaline earth metal compound (c-3) is not particularly limited. The content of the alkaline earth metal compound (c-3) is, for example, 0.05 mass% or more and 20 mass% or less of the solid content of the anticorrosion coating composition. When the content of the alkaline earth metal compound (c-3) is 0.05 mass% or more, the effects of the alkaline earth metal compound (c-3) are easily exhibited. As the alkaline earth metal compound (c-3) dissolves, the coating film can become alkaline. When the content of the alkaline earth metal compound (c-3) is 20 mass% or less, deterioration of the coating film due to an increase in pH is suppressed.

[0067] The content of the alkaline earth metal compound (c-3) may be 0.1% by mass or more, 0.5% by mass or more, or 1.0% by mass or more, and may be 15.0% by mass or less, or 12.0% by mass or less.

[0068] The content ratio (c-1 / c-3) of the metal sulfate (c-1) to the alkaline earth metal compound (c-3) is not particularly limited. The content ratio (c-1 / c-3) may be, for example, 0.05 or more and 20 or less on a mass basis. This may further improve corrosion resistance. The content ratio (c-1 / c-3) may be 0.1 or more, or 0.9 or more. The content ratio (c-1 / c-3) may be 18.0 or less, 15.0 or less, 10.0 or less, 5.0 or less, or 2.0 or less.

[0069] Other Rust Inhibitors (c-4) The powder (c) may contain a rust inhibitor (c-4) other than those described above. The other rust inhibitor (c-4) is not particularly limited as long as it does not interfere with the effects of the present disclosure. Examples of the other rust inhibitor (c-4) include those commonly used as rust inhibitors. Examples of the other rust inhibitor (c-4) include zinc, zinc alloys, calcium phosphite, aluminum phosphate, zinc phosphate, zinc molybdate, aluminum molybdate, and aluminum powder. These may be used alone or in combination of two or more.

[0070] The content of the other rust inhibitor (c-4) is, for example, 8% by mass or less of the solid content of the anticorrosion coating composition, and may be 5% by mass or less, 3% by mass or less, or 0% by mass.

[0071] Pigment The anticorrosion coating composition may contain a pigment. Examples of pigments include, without limitation, pigments that are typically incorporated into coating compositions. Examples of pigments include extender pigments and coloring pigments. These may be used alone or in combination of two or more.

[0072] The anticorrosion coating composition may contain a white pigment. The white pigment improves the hiding power of the anticorrosion coating composition while minimizing the effect on the hue of the topcoat. If the anticorrosion coating composition has sufficient hiding power, the white pigment may not be contained. A representative example of the white pigment is titanium dioxide. The content of the white pigment is not particularly limited. The content of the white pigment may be, for example, 5% by mass or more and 60% by mass or less of the solid content of the anticorrosion coating composition. The content of the white pigment may be 10% by mass or more, 15% by mass or more, or 20% by mass or more. The content of the white pigment may be 40% by mass or less, or 30% by mass or less.

[0073] Extender pigments include, for example, talc, clay, calcium carbonate, magnesium carbonate, barium sulfate, silicic acid, silicates, aluminum oxide hydrate, calcium sulfate, gypsum, micaceous iron oxide (MIO), glass flake, szolite mica, and clarite mica. These may be used alone or in combination of two or more. The amount of extender pigment is not particularly limited.

[0074] Coloring 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-based red and yellow pigments. These may be used alone or in combination of two or more. The content of the coloring pigment is not particularly limited.

[0075] The total content of the powder (C) and various pigments is, for example, 30% or more and 60% or less in terms of pigment volume concentration (PVC). This ensures hiding power while suppressing the occurrence of coating film cracking and deterioration of adhesion. The PVC is the volume percentage (%) of the powder (C) and various pigments relative to the total volume of the total resin solids, powder (C), and various pigments in the corrosion-resistant coating composition.

[0076] Other Resins The anticorrosive coating composition may contain resins other than the epoxy resin (a). Examples of other resins include xylene resins, acrylic resins, and polyester resins. These may be used alone or in combination of two or more.

[0077] The content of the solvent is, for example, 5% by mass or more and 50% by mass or less of the total mass of the anticorrosion coating composition.

[0078] Examples of the solvent include those commonly used in the art, such as toluene, xylene, isobutyl alcohol, methyl ethyl ketone, and weak solvents, which may be used alone or in combination of two or more.

[0079] The anticorrosion coating composition may contain a weak solvent. The content of the weak solvent is, for example, 5% by mass or more and 50% by mass or less of the total mass of the anticorrosion coating composition.

[0080] The weak solvent is an aliphatic hydrocarbon compound. Examples of weak solvents include single-component solvents such as n-butane, n-hexane, n-heptane, n-octane, isononane, n-decane, n-dodecane, cyclopentane, cyclohexane, and cyclobutane; and mixed solvents such as mineral spirits, white spirits, mineral turpentine, isoparaffin, solvent kerosene, aromatic naphtha, VM&P naphtha, and solvent naphtha. These may be used alone or in combination of two or more.

[0081] Commercially available weak solvents include "Solvesso 100," "Solvesso 150," and "Solvesso 200" (all trade names, manufactured by Esso Oil Co., Ltd.), "Swasol 310," "Swasol 1000," and "Swasol 1500" (all trade names, manufactured by Cosmo Oil Co., Ltd.).

[0082] Others The anticorrosion coating composition may contain other components, such as a silane coupling agent and various additives.

[0083] The silane coupling agent improves adhesion between the primer coating film and the metal substrate. The silane coupling agent 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 anticorrosion coating composition.

[0084] Examples of the additives include anti-sagging agents, anti-settling agents, anti-color separation agents, anti-foaming agents, anti-popping agents, leveling agents, and matting agents.

[0085] (Preparation Method) The two-component anticorrosive coating composition is prepared by mixing the base agent, the curing agent, and, if necessary, the diluent, etc., by the method described above. The base agent and the curing agent are usually mixed immediately before use (for example, the composition is used within 60 minutes after mixing the respective components). The diluent can be exemplified by the same solvents as above.

[0086] The base agent is prepared by mixing the above components by a method known to those skilled in the art. For mixing, a commonly used mixing device such as a paint shaker or mixer is used. The same method is used to prepare the curing agent.

[0087] (Coating Method) The anticorrosive coating composition is applied by a common method such as with a brush, roller or spray.

[0088] (Primer Coating Film) The anticorrosive coating composition forms a primer coating film with excellent anticorrosion properties. The thickness of the primer coating film is not particularly limited and can be appropriately set depending on the type of substrate, application, etc. The dry film thickness of the primer coating film is, for example, 10 μm or more and 300 μm or less. The anticorrosive coating composition may be applied multiple times to form a primer coating film with a laminated structure.

[0089] (Substrate) The substrate to be coated with the anticorrosive coating composition is not particularly limited as long as corrosion resistance is required. The substrate is typically a metal. Examples of metals include iron, copper, aluminum, tin, zinc, and alloys thereof.

[0090] Specific examples of substrates include cold-rolled steel sheets, hot-rolled steel sheets, stainless steel, electrogalvanized steel sheets, hot-dip galvanized steel sheets, zinc-aluminum alloy-plated steel sheets, zinc-iron alloy-plated steel sheets, zinc-magnesium alloy-plated steel sheets, zinc-aluminum-magnesium alloy-plated steel sheets, aluminum-plated steel sheets, aluminum-silicon alloy-plated steel sheets, and tin-plated steel sheets. More specific examples of substrates include ships, vehicles (e.g., railway cars and large vehicles), aircraft, bridges, offshore structures, plants, tanks (e.g., oil tanks), pipes, steel pipes, cast iron pipes, and other steel structures and buildings.

[0091] The substrate may be one that has been subjected to blasting, anti-rust coating, shop primer coating, or organic or inorganic zinc-rich primer coating. The substrate may have a previous coating film (a coating film other than the primer coating that was formed before the primer coating film was formed). The substrate may have corrosion products on its surface.

[0092] (Other Coatings) Other coatings may be formed on the primer coating, such as a topcoat paint and / or a functional paint.

[0093] 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 self-cleaning properties against pollutants, and antifouling paints that prevent the adhesion of marine organisms, etc.

[0094] Hereinafter, the present embodiment will be described in more detail using examples, but the present embodiment is not limited to these examples. In the examples, "parts" and "%" are by mass unless otherwise specified.

[0095] [Production Example 1] Preparation of Epoxy Resin (a) 250 g of p-tert-butylphenol novolac resin (trade name: Hitanol #1133, manufactured by Hitachi Chemical Co., Ltd.), 250 g of octylphenol novolac resin (trade name: Hitanol #1501, manufactured by Hitachi Chemical Co., Ltd.), and 1,440 g of epichlorohydrin were charged into a 2-L reactor equipped with a thermometer, a stirrer, and a condenser, and stirred to form a homogeneous solution. Next, 268 g of 48% by mass sodium hydroxide was added dropwise at 60 to 110°C over 2 hours. During this time, the water generated in the system was azeotropically distilled with epichlorohydrin and removed from the system using a water separator, while the epichlorohydrin was refluxed within the system. After completion of the dropwise addition, the mixture was aged at 100 to 120°C for 2 hours, and the reaction was terminated when the theoretical amount of water had flowed out.

[0096] 150 g of xylene was added to the resulting epichlorohydrin solution of the epoxy compound, and the mixture was washed with a large amount of water. After removing the resulting sodium chloride and excess sodium hydroxide, the mixture was neutralized with a 3% by mass aqueous phosphoric acid solution. Next, the epichlorohydrin and xylene were distilled off under reduced pressure, and 460 g of a high-boiling paraffin solvent (product name: Swazol 310, manufactured by Cosmo Oil Co., Ltd.) was added to obtain a liquid epoxy resin (a) (novolac-type epoxy resin). The epoxy resin (a) had a weight-average molecular weight of 8,500, an epoxy equivalent of 1,010 g / eq, and a solids content of 60% by mass.

[0097] [Examples 1 to 49, Comparative Examples 1 to 24] Base agents and curing agents were prepared according to the formulations shown in Tables 1 to 10. Anticorrosion coating compositions were prepared by mixing the base agents and curing agents. The blending amounts in Tables 1 to 10 are mass ratios relative to 100 parts by mass of the solid content of the anticorrosion coating composition. A weak solvent (trade name "Solvesso 100", manufactured by Esso Oil Co., Ltd.) was added in an appropriate amount so that the solid content (NV) of the anticorrosion coating composition would be as shown in Tables 1 to 10.

[0098] Details of each component shown in Tables 1 to 10 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

[0099] Alkylphenols o-tert-butylphenol thickener Product name F-9050, manufactured by Kusumoto Chemicals Co., Ltd. Defoaming agent Product name Disparlon 1958, manufactured by Kusumoto Chemicals Co., Ltd. Weak solvent Solvesso 100, manufactured by Esso Oil Co., Ltd.

[0100] Metal sulfate (c-1) The amount dissolved in 100 g of water at 5°C is shown in parentheses. Aluminum sulfate (32.2 g) Nickel sulfate hexahydrate (39.1 g) Magnesium sulfate (25.4 g)

[0101] Zinc compound (c-2) The amounts dissolved in 100 g of water at 20°C and pH 7.0 are shown in parentheses, and the amounts dissolved in 100 g of water at 20°C and pH 5.0 are shown in parentheses. Zinc carbonate (0.000470 g, >8.13 g) Zinc oxide (0.000394 g, >12.5 g)

[0102] Alkaline earth metal compound (c-3) The amount dissolved in 100 g of water at 20°C is shown in parentheses. Calcium oxide (0.112 g) Barium oxide (3.48 g) Calcium hydroxide (0.173 g) Barium hydroxide (3.89 g)

[0103] The average particle size of each of the powders (c) was 0.1 to 40 μm.

[0104] [Evaluation] The anticorrosion coating compositions were evaluated by the following methods, and the evaluation results are shown in Tables 1 to 10.

[0105] (1) Corrosion resistance TP Giken SS400 grid blast steel plates were exposed to the coastal area of ​​Tamano City, Okayama Prefecture for three months to obtain rusted plates, which were then subjected to four types of surface treatment. Next, the salt concentration of the rusted plate surface was adjusted using a sodium chloride aqueous solution. As a result, seven types of surface salt concentrations (salt concentration 5±5 mg / m２ , 30±5 mg / m ２ , 50±5 mg / m ２ , 100±30mg / m ２ , 200±30mg / m ２ , 500±100mg / m ２ , 1000±200mg / m ２ The surface salt concentration was measured using a surface salinity meter SNA-3000 manufactured by Sanko Electronics Laboratory Co., Ltd., and the salt concentration (mg / m) was measured 1 minute after the start of measurement. ２ ) values ​​were adopted.

[0106] The anticorrosion coating composition was spray-coated onto each test plate, and then dried at 23° C. for one week to prepare a coated plate having a primer coating film with a thickness of 60 μm.

[0107] The resulting coated panels (75 mm x 150 mm) were subjected to a combined cyclic corrosion test in accordance with the cycle D method (CCT) of the cyclic corrosion test method specified in JIS K5600-7-9:2006. Specifically, a 120-cycle accelerated corrosion test was performed using the D mode of a combined cyclic corrosion tester (manufactured by Suga Test Instruments Co., Ltd., Model CCT-1). The number of rust spots that occurred after the test was evaluated. A rating of level 7 or higher indicates high corrosion resistance.

[0108] (Evaluation criteria) 10: 0 9: Less than 10 8: 10 or more but less than 20 7: 20 or more but less than 50 6: 50 or more but less than 100 5: 100 or more but less than 200 4: 200 or more but less than 400 3: 400 or more but less than 600 2: 600 or more but less than 800 1: 800 or more

[0109] (2) Color The anticorrosion coating composition was spray-painted onto degreased SPCC-SB (cold-rolled steel plate with a bright finish as specified in JIS G 3141:2017), and then dried at 23°C for one week to prepare a coated plate having a primer coating film with a thickness of 60 μm. ＊ a ＊ b ＊ L in color system ＊ Value, a ＊ value and b ＊The values ​​were measured using a spectrophotometer (CR-400, manufactured by Konica Minolta, Inc.). Evaluation A means that the anticorrosion coating composition is white to pale in color, indicating a high degree of freedom in color design. Evaluation B means that the anticorrosion coating composition is colored. The coating film obtained with the anticorrosion coating composition of Comparative Example 19 was gray in color.

[0110] (Evaluation criteria) A:L ＊ ≧70, −5.0≦a ＊ , b ＊ ≦5.0 B:L ＊ <70, -5.0>a ＊ , b ＊ , a ＊ , b ＊ >5.0

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[0121] The present invention provides an anticorrosion coating composition that has excellent corrosion resistance and allows for a high degree of freedom in color design, and is therefore particularly suitable as an undercoat for steel materials used in large structures such as plants, bridges, steel towers, and buildings.

Claims

1. An anticorrosion coating composition comprising: an epoxy resin (a); a polyamine (b); and a powder (c), wherein the powder (c) comprises: a metal sulfate (c-1) having a solubility of 0.1 g or more in 100 g of water at 5°C; and a white zinc compound (c-2) having a solubility of 0.005 g or less in 100 g of water at a pH greater than 5.0 and at 20°C, and a solubility of 0.05 g or more in 100 g of water at a pH of 5.0 or less and at 20°C, wherein the content of the metal sulfate (c-1) is 0.05% by mass or more and 20% by mass or less of the solid content of the anticorrosion coating composition; and the content of the zinc compound (c-2) is 5% by mass or more and 60% by mass or less of the solid content of the anticorrosion coating composition.

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

3. The anticorrosion coating composition according to claim 2, wherein the content of the alkaline earth metal compound (c-3) is 0.05 mass % or more and 20 mass % or less of the solid content of the anticorrosion coating composition.

4. The anticorrosion coating composition according to claim 2 or 3, 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.

5. The anticorrosion coating composition according to any one of claims 1 to 4, wherein the metal sulfate (c-1) is a salt of a polyvalent metal cation and a sulfate ion.

6. The corrosion-protective coating composition according to any one of claims 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 corrosion-preventive coating composition according to any one of claims 1 to 6, wherein the zinc compound (c-2) comprises at least one selected from the group consisting of zinc oxide, zinc hydroxide, and zinc carbonate.

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