Anticorrosion coating composition

Abstract

SOLUTION: An anticorrosive coating composition contains (A) epoxy resin, (B) amine curing agent, (C) reactive butadiene acrylonitrile and (D) magnesium oxide, the (D) magnesium oxide having a BET specific surface area of 3.0 m2 / g or more, the solid content of the (D) magnesium oxide being 5-15 mass%.EFFECT: An anticorrosive coating composition can be directly applied to a rusted face and can form a coating layer having excellent anticorrosive and adhesive properties and also having excellent flexibility.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an anticorrosion coating composition, and more particularly to an anticorrosion coating composition containing an epoxy resin and having excellent anticorrosion properties and adhesion. [Background technology]

[0002] Steel structures are used in a variety of applications and environments. However, they are susceptible to corrosion due to various factors, which can lead to a decrease in strength due to rusting and the risk of collapse. A variety of methods, such as painting, metal spraying, and lining, are used to prevent corrosion.

[0003] Corrosion prevention through painting can extend the service life of steel structures by regularly repainting them, and regular maintenance can help maintain steel structures over the long term.

[0004] Patent Document 1 describes a coating containing MgO, amino acids, and a film-forming resin, and states that this coating is a corrosion-resistant coating that does not contain toxic chromate pigments.

[0005] Patent Document 2 describes an epoxy resin composition that contains a main component containing a liquid epoxy resin and a silane coupling agent, and a curing agent component containing an amine-based curing agent, and the main component and / or the curing agent component contains a liquid hydrocarbon resin, and describes that this epoxy resin composition can form a coating on the surface of the substrate that has excellent adhesion to the substrate, water resistance, and corrosion resistance.

[0006] Patent Document 3 describes an epoxy resin composition containing a difunctional or higher epoxy resin derived from a higher fatty acid or a derivative thereof, an epoxy resin other than the above epoxy resin, a terminally reactive butadiene-acrylonitrile copolymer, and a polyamidoamine, and describes that this epoxy resin composition can follow cracks and can protect concrete structures on wet surfaces by a simple method such as roller coating or brush coating.

[0007] Patent Document 4 describes an anti-rust coating composition containing a coating film-forming resin selected from epoxy resins and the like, a crosslinking agent, and magnesium oxide, wherein the magnesium oxide has a lattice constant of less than 0.4214 nm and a BET specific surface area of ​​2.0 m 2 / g or less, and it is described that this anti-rust coating composition can exhibit excellent anti-rust properties over a long period of time and can also form a coating film that exhibits excellent moisture resistance. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2016-537481 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-15572 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-59195 [Patent Document 4] Patent No. 6690046 Summary of the Invention [Problem to be solved by the invention]

[0009] Normally, when rust or other abnormalities appear on steel structures due to various factors, it is necessary to completely remove the rust using blasting or other methods, but this process requires a great deal of time and effort, and there are problems with some areas of the structure that make it difficult to treat. For this reason, there has been a demand for a paint that can simplify the process of removing rust and that can provide good corrosion prevention and adhesion even when applied directly to rusted areas.

[0010] The compositions and the like described in Patent Documents 1, 2, and 4 are not intended to be directly applied to rusted areas. Furthermore, although Patent Document 3 describes the composition's adhesion to rusted surfaces, there is a demand for even better adhesion to rusted surfaces.

[0011] An object of the present invention is to provide an anticorrosive coating composition that can be applied directly to a rusted surface and can form a coating film that has good corrosion prevention and adhesion properties and excellent flexibility. [Means for solving the problem]

[0012] To achieve the above object, the present invention provides an anticorrosion coating composition containing (A) an epoxy resin, (B) an amine curing agent, (C) a reactive butadiene acrylonitrile, and (D) magnesium oxide, wherein the magnesium oxide (D) has a BET specific surface area of ​​3.0 m 2 / g or more, and the content of the magnesium oxide (D) is 5 to 15 mass % of the solid content.

[0013] The anticorrosive coating composition preferably further contains (E) a non-reactive diluent, and the (E) non-reactive diluent preferably contains a liquid hydrocarbon resin.

[0014] The epoxy resin (A) is preferably in a liquid state at a temperature of 15 to 25°C. In the anticorrosive coating composition, the amine curing agent (B) preferably contains a phenalkamine (b1) and a polyamidoamine (b2).

[0015] The anticorrosion coating composition preferably further contains at least one selected from (F) a reactive diluent and (G) a silane coupling agent.

[0016] The reactive butadiene acrylonitrile (C) preferably contains a functional group at the terminal that reacts with an epoxy group.

[0017] The anticorrosion coating composition can be suitably used on rusted surfaces.

[0018] Another invention that achieves the above object is an anticorrosion coating film formed from the above anticorrosion coating composition.

[0019] Another invention that achieves the above object is a substrate with a corrosion-resistant coating, comprising the above corrosion-resistant coating and a substrate.

[0020] A preferred embodiment of the substrate with a corrosion-resistant coating film is one in which the substrate has a rusted surface and the corrosion-resistant coating film is in direct contact with the rusted surface of the substrate.

[0021] Another invention that achieves the above object is a method for producing a substrate with a corrosion-protective coating, which includes the following steps [1] and [2]. [1] A step of applying the anticorrosive coating composition to a substrate. [2] A step of drying the applied anticorrosion coating composition to form a coating film. [Effects of the Invention]

[0022] The anticorrosive coating composition of the present invention can be applied directly to a rusted surface and can form a coating film that has good anticorrosion properties and adhesion, as well as excellent flexibility. DETAILED DESCRIPTION OF THE INVENTION

[0023] The anticorrosion coating composition of the present invention contains (A) an epoxy resin, (B) an amine curing agent, (C) a reactive butadiene acrylonitrile, and (D) magnesium oxide, and preferably further contains (E) a non-reactive diluent.

[0024] <(A) Epoxy resin> The epoxy resin (A) is preferably liquid at room temperature (15 to 25°C) and has a viscosity in the range of 800 to 25,000 mPa·s. Examples of such epoxy resins (A) include polymers or oligomers containing two or more epoxy groups in the molecule, and polymers or oligomers produced by the ring-opening reaction of such epoxy groups. Such epoxy resins (A) are effective in further improving penetration into the rust.

[0025] Examples of such liquid epoxy resins (A) include bisphenol-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, phenol novolac-type epoxy resins, cresol-type epoxy resins, dimer acid-modified epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, and epoxidized oil-based epoxy resins. Among these, bisphenol-type epoxy resins are preferred, with bisphenol A-type and F-type epoxy resins being more preferred, and bisphenol A-type epoxy resins being particularly preferred. Use of bisphenol-type epoxy resins allows for the formation of coating films with excellent adhesion to substrates and corrosion resistance. Among such epoxy resins (A), so-called bisphenol A type epoxy resins (epoxy equivalent weight: 150 to 1000 (g / equiv)) are preferred.

[0026] Particularly preferred examples of bisphenol A type epoxy resins include condensation polymers of bisphenol A type diglycidyl ethers such as bisphenol A diglycidyl ether, bisphenol A polypropylene oxide diglycidyl ether, bisphenol A ethylene oxide diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and hydrogenated bisphenol A propylene oxide diglycidyl ether.

[0027] In the present invention, the (A) epoxy resin may be used alone or in combination of two or more. When two or more (A) epoxy resins are used in combination, the molecular weight and epoxy equivalent (g / equiv) of the (A) epoxy resin are both expressed as their average values.

[0028] The average molecular weight and other properties of the (A) epoxy resin are not universally determined, as they depend on the coating and curing conditions of the resulting coating (e.g., ambient drying or baking), but it is generally preferred that the molecular weight be 300 to 750, the viscosity be 9,000 to 23,000 mPa·s, and the epoxy equivalent be in the range of 150 to 300, since this will enable the formation of a coating film that is excellent in application workability, adhesion to the substrate, water resistance, and corrosion resistance.

[0029] Representative examples of the epoxy resin (A) include "Epikote 828 (trade name), generic name: bisphenol A diglycidyl ether" (manufactured by Shell Chemical Industries, Ltd., weight-average molecular weight approximately 360, epoxy equivalent weight 180 to 190, viscosity 12,000 to 15,000 mPa·s / 25°C), "Epotohto YDF-170 (trade name), generic name: bisphenol F diglycidyl ether" (manufactured by Tohto Kasei Co., Ltd., epoxy equivalent weight 160 to 180, viscosity 2,000 to 5,000 mPa·s / 25°C), and "Frep 60 (trade name)" (manufactured by Toray Thiokol Co., Ltd., epoxy equivalent weight approximately 280, viscosity approximately 17,000 mPa·s / 25°C).

[0030] In the present invention, even if the epoxy resin is semi-solid at room temperature, it can be used in a liquid state by appropriately diluting it. An example of an epoxy resin that is semi-solid at room temperature is "Epicoat 834 (trade name), general name: bisphenol A type epoxy resin" (manufactured by Japan Epoxy Resins Co., Ltd., epoxy equivalent 230 to 270, viscosity P to U / 25°C according to the Gardner / Holtz method).

[0031] In the anticorrosion coating composition of the present invention, the content of the epoxy resin (A) is usually 5 to 40 mass %, preferably 10 to 30 mass %, of the solid content of the anticorrosion coating composition. By containing the epoxy resin (A) in this amount in the anticorrosion coating composition of the present invention, a coating film excellent in adhesion to substrates, water resistance, and corrosion prevention can be formed.

[0032] The solid content of the anticorrosion coating composition of the present invention refers to the mass percentage of the coating film (heating residue) after the anticorrosion coating composition has been fully cured (heated), or the coating film (heating residue) itself. The solid content can be calculated according to JIS K 5601-1-2 by weighing 1±0.1 g of the anticorrosion coating composition (e.g., a composition immediately after mixing the base component and curing agent component) onto a flat-bottom dish, spreading it evenly using a wire of known mass, drying it at 23°C for 24 hours, and then heating it at 110°C for 1 hour (at normal pressure). The solid content is equivalent to the total solid content (components other than the solvent) of the raw materials used in the anticorrosion coating composition of the present invention.

[0033] <(B) Amine curing agent> The (B) amine curing agent is not particularly limited, but examples include (b1) phenalkamine, (b2) polyamidoamine, and polyetheramine, with (b1) phenalkamine and (b2) polyamidoamine being particularly preferred. Because (b1) phenalkamine easily penetrates into the rust, using (b1) phenalkamine as a curing agent results in a paint that exhibits good adhesion to rusted surfaces. However, because (b1) phenalkamine has a low molecular weight, its use alone may result in a decrease in the elongation of the coating film. For this reason, when using (b1) phenalkamine, it is preferable to use (b2) polyamidoamine in combination. The inclusion of (b2) polyamidoamine allows the formation of a flexible, tough coating film on the rust, resulting in a coating that is resistant to cracking and peeling even on poor substrate conditions. Polyetheramine also improves penetration into the rust.

[0034] (b1) Phenalkamine is an epoxy curing agent composed of cardanol, formaldehyde, and an organic diamine. Cardanol is prepared from cashew nut shell liquid (CNSL). Phenalkamine can be prepared by the Mannich reaction to prepare a low molecular weight polymer by condensing 1 mol of alkylphenol, 2 mol of formaldehyde, and 2 mol of polyamine. The polyamine can be aromatic or aliphatic.

[0035] (b1) Commercially available products containing phenalkamine include Cardolite NC-540 (manufactured by Cardolite), Cardolite NC-541 (manufactured by Cardolite), and Ultra Lite 2009 (manufactured by Air Products), which are phenalkamine-based compounds, and Ancamine 2792 (manufactured by Air Products), which is a mixture of phenalkamine and polyetheramine.

[0036] (b2) Polyamidoamines are mainly produced by condensation of dimer acid and polyamine, and include those having reactive primary and secondary amino groups in the molecule. The molecular weight, viscosity, amine value, etc. of the polyamidoamine vary depending on the molar ratio of dimer acid to polyamine, the ratio of monomer acid / dimer acid / trimer acid in the fatty acid composition, the type of polymer, and the number of functional groups.

[0037] (b2) Commercially available polyamidoamines include, for example, Ancamide(R) 2353 (manufactured by Air Products, modified alicyclic polyamidoamine), Ancamide(R) 2396A (manufactured by Air Products, modified alicyclic polyamidoamine); Tomide(R) 210 (amine value 100, semi-solid), Tomide(R) 215X (amine value 220, viscosity: 500 to 700 poise / 40°C), Tomide(R) 225X (amine value 300, 80 to 120 poise / 40°C), Tomide(R) 2500 (amine value 330, 5 to 10 poise / 25°C), Tomide(R) 213A (polyamide adduct, amine value 85, xylene / butanol 50% solution), Tomide(R) 238 (polyamidoamine), The Tomide series, such as Versamid® 100 (amine value 90, semi-solid), Versamid® 115 (amine value 240), Versamid® 125 (amine value 345, 75-100 poise / 40°C), and Versamid® 230 (polyamide adduct, amine value 125, 60% xylene / butanol solution), all manufactured by Henkel Hakusui Chemical; the Zenamide series, such as Zenamide® 250 (amine value 440, 5-10 poise / 25°C) and Zenamide® 2000 (amine value 600, 10-25 poise / 25°C), all manufactured by Henkel Japan; and Luccamide® N-153 IM. Luckamide series such as 65 (amine value 100, xylene / butanol 65% solution), Luckamide(R) TD966 (amine value 170, xylene / butanol 60% solution), Luckamide(R) TD973 (polyamine adduct, amine value 170, xylene / butanol 60% solution) (all manufactured by Dainippon Ink Co., Ltd.); Sanmaid(R) 300 (amine value 90, semi-solid ), Sanmaid(R) 306 (amine value 210, 500-700 poise / 40°C), Sanmaid(R) 316 (amine value 310, 90-110 poise / 40°C), Sanmaid(R) X-2000 (amine value 400, 10-30 poise / 25°C), Sanmaid(R) X-2282 (amine value 150, 4-9 poise / 25°C) and other Sanmaid series (all manufactured by Sanwa Chemical Co., Ltd.);Examples include the Polymide series, such as Polymide(R) L-10-3 (amine value 100, semi-solid) and Polymide(R) L-55-3 (amine value 380, 9.5 to 25.5 poise / 20°C) (all manufactured by Sanyo Chemical Industry Co., Ltd.). Examples of polyamidoamines obtained by modifying polyoxyalkylene polyamines with polycarboxylic acids include Ancamide(R) 910 (manufactured by Air Products Co., Ltd.), which is a polyamidoamine obtained by modifying diethylene glycol diaminopropyl ether with dimer acid. The (R) in the above product names indicates a registered trademark.

[0038] Other examples include copolymerized polyamides obtained by polycondensation of two or more of the above-mentioned polyamide-forming amines or acids, and polyamideimides (reaction products of trimellitic anhydride and aromatic diamines).

[0039] These polyamidoamines may be used singly or in combination of two or more. These polyamide amine curing agents are prepared to an NV of 50 to 100%, and the viscosity measured with an E-type viscometer is preferably in the range of 100 to 100,000 cPs, and more preferably 500 to 10,000 cPs, for superior handling and coating properties.

[0040] Among such polyamidoamines (b2), it is preferable to use modified alicyclic polyamidoamines from the viewpoint of application adhesion to rusted surfaces, and it is more preferable to use polyamidoamines in which polyoxyalkylene polyamines are modified with polycarboxylic acids from the viewpoint of imparting flexibility to the coating film.

[0041] Examples of modified alicyclic polyamidoamines include the above-mentioned ANKAMIDE® 2353 and ANKAMIDE® 2396A, etc. Examples of polyamidoamines in which polyoxyalkylene polyamines are modified with polycarboxylic acids include the above-mentioned ANKAMIDE® 910, which is a polyamidoamine in which diethylene glycol diaminopropyl ether is modified with dimer acid.

[0042] (b2) When a curing agent having a larger molecular weight than polyamines is used as the polyamidoamine, an anticorrosion coating composition having excellent low-temperature curing properties can be obtained. The polyetheramine may, for example, be a compound represented by the following structural formula (1).

[0043] [ka] (In the formula, R 1 is a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a t-butyl group, and R 2 are independently an ethylene group, a 1,2-propylene group, a 2,3-propylene group, or a 1,3-propylene group; R 3 represents a methylene group, an ethylene group, a 1,2-propylene group, a 2,3-propylene group, or a 1,3-propylene group, and n represents the average value of the repeating units and is 2 to 100.

[0044] The molecular weight of the polyetheramine is preferably 300 to 5,000 in weight average molecular weight (Mw), more preferably 400 to 1,500, from the viewpoint that a composition excellent in storage stability and anticorrosion properties can be easily obtained.

[0045] As the polyetheramine, commercially available products may be used, and examples of such commercially available products include "JEFFAMINE D-230," "JEFFAMINE D-400," "JEFFAMINE M-600," "JEFFAMINE M-1000," and "JEFFAMINE M-2005" (all manufactured by Huntsman).

[0046] In the anticorrosion coating composition of the present invention, the content of the amine curing agent (B) is usually 5 to 30 mass %, preferably 8 to 20 mass %, of the solid content of the anticorrosion coating composition. By including the amine curing agent (B) in the anticorrosion coating composition of the present invention in this amount, a coating having good adhesion can be obtained.

[0047] In addition to (b1) phenalkamine and (b2) polyamidoamine, a conventionally known amine curing agent, for example, a polyamine compound that is usually used as an epoxy resin curing agent, such as an aliphatic polyamine, modified aliphatic polyamine, alicyclic polyamine, modified alicyclic polyamine, aromatic polyamine, or modified aromatic polyamine, may be used in combination, provided that the effects of the present invention are not impaired. Furthermore, examples of the thermal latent curing agent include dicyandiamide.

[0048] <(C) Reactive butadiene acrylonitrile> (C) Reactive butadiene acrylonitrile imparts flexibility and pliability to the coating film, improving its crack resistance. Therefore, when the anticorrosion coating composition of the present invention is applied directly to a rusted surface, the coating film adheres accurately to the rusted surface, forming a flexible, tough coating film on the rust, which prevents cracking and peeling even on poor substrate conditions. Furthermore, because it is incorporated into the structural skeleton of the coating film during the reactive curing process, it reduces the drawback of impaired water resistance that is a problem with coatings blended with non-reactive rubber components.

[0049] (C) Reactive butadiene acrylonitrile includes those having an acrylonitrile polybutadiene skeleton in the main chain and having a functional group reactive with an epoxy group, such as an amino group, a carboxyl group, or a hydroxyl group, at the end.

[0050] Examples of such (C) reactive butadiene acrylonitriles include Hypro® ATBN 1300X16 (manufactured by CVC THERMOSET SPECIALITIES) and Hypro® ATBN 1300X42 (manufactured by CVC THERMOSET SPECIALITIES), which have terminal amino groups, and Hypro® CTBN 1300X8 (manufactured by CVC THERMOSET SPECIALITIES) and Hypro® CTBN1300X31 (manufactured by CVC THERMOSET SPECIALITIES), which have terminal carboxyl groups.

[0051] A preferred type of such (C) reactive butadiene acrylonitrile comprises structural units selected from the following formulae (Ia) to (Id) and terminal groups selected from the following formulae (IIa) to (IId).

[0052] [ka] (In the formula, Ra represents a hydrogen atom or a methyl group, Rb represents —COOH, —COORc, or —CONH2, and Rc represents an aliphatic group, preferably a methyl group.)

[0053] [ka] (In the formula, R represents an alkylene group.)

[0054] The proportion of the structural units represented by formulae (Ia), (Ib) and (Ic) is preferably 5 to 50% by mass, and the proportion of the structural unit represented by formula (Id) is preferably 0 to 30% by mass.

[0055] In the anticorrosion coating composition of the present invention, the content of (C) reactive butadiene acrylonitrile is usually 0.1 to 2.0 mass %, preferably 0.2 to 1.0 mass %, of the solid content of the anticorrosion coating composition. By containing (C) reactive butadiene acrylonitrile in the anticorrosion coating composition of the present invention in this amount, the coating workability and the like are improved and flexibility is imparted to the coating film.

[0056] <(D) Magnesium oxide> (D) Magnesium oxide (MgO) continuously releases corrosion inhibitors, thereby inhibiting corrosion beneath the coating film and in areas where the coating film is missing, thereby imparting excellent long-term rust prevention to the anticorrosive coating composition. Furthermore, it imparts excellent moisture resistance to the coating film. Furthermore, if a coating film is formed on an iron surface (steel) and then the anticorrosive coating composition of the present invention is applied directly to the surface where rust has developed, (D) magnesium oxide reacts with traces of water remaining in the old coating film (MgO + HO → Mg(OH)), trapping the water and preventing rust from corroding the iron surface (steel).

[0057] (D) Magnesium oxide has a BET specific surface area of ​​3.0 m 2 / g or more, preferably 10m 2 / g or more, more preferably 30m 2 The upper limit of the BET specific surface area is not particularly limited, but for example, 300 m 2 / g. The BET specific surface area is 3.0 m 2 When the magnesium oxide has a saturation of 1 / g or more, the activity of the magnesium oxide is high, the growth of rust can be rapidly stopped, and the anticorrosive coating composition exhibits excellent anticorrosion properties even when applied directly to a rusted surface.

[0058] The BET specific surface area of ​​magnesium oxide can be adjusted by the firing temperature during production of magnesium oxide. In this specification, the BET specific surface area can be measured using, for example, an automatic specific surface area measuring device Gemini VII23900 (manufactured by Shimadzu Corporation).

[0059] In the anticorrosion coating composition of the present invention, the content of (D) magnesium oxide is 5 to 15 mass %, preferably 6 to 14 mass %, and more preferably 8 to 12 mass %, of the solid content of the anticorrosion coating composition. By containing (D) magnesium oxide in the anticorrosion coating composition of the present invention in this amount, excellent corrosion prevention properties are obtained, and even when the anticorrosion coating composition is applied directly to a rusted surface, excellent corrosion prevention properties are exhibited.

[0060] <(E) Non-reactive diluent> The (E) non-reactive diluent is a component that has no reactivity in the anticorrosion coating composition and acts as a plasticizer. The (E) non-reactive diluent has the function of improving the flexibility of the coating film. It also has the function of improving the penetration of the anticorrosion coating composition into rust and covering the surface of the rust, thereby inhibiting the spread of rust. In addition, the (E) non-reactive diluent has a low viscosity, which makes it possible to make the coating highly solid.

[0061] As the (E) non-reactive diluent, a liquid hydrocarbon resin that is liquid at room temperature (15 to 25°C) and has a viscosity in the range of 500 to 400,000 mPa·s / 25°C is suitable, and specific examples of suitable diluents include cardanol and its derivatives, and xylene resins.

[0062] In this case, the cardanol derivative (excluding the amine curing agent (B)) refers to a compound formed by modifying the hydroxyl group, unsaturated aliphatic side chain, or benzene ring of cardanol prepared from cashew nut shell liquid (CNSL) with a functional group that is unreactive with epoxy groups or amino groups.

[0063] Commercially available products of cardanol and its derivatives include LITE 2020 (manufactured by Cardolite) and NX-2024 (manufactured by Cardolite), and commercially available products of xylene resins include Nikanol Y-2000(-1000 (manufactured by Fudo Co., Ltd.), Nikanol L (manufactured by Fudo Co., Ltd.), and Nikanol H (manufactured by Fudo Co., Ltd.).

[0064] In the anticorrosion coating composition of the present invention, the content of the nonreactive diluent (E) is usually 0.1 to 10.0 mass %, preferably 0.5 to 5.0 mass %, of the solid content of the anticorrosion coating composition. By containing the nonreactive diluent (E) in the above amount in the anticorrosion coating composition of the present invention, the spread of rust can be effectively suppressed.

[0065] <Optional ingredients> The anticorrosion coating composition of the present invention may further contain, as optional components, (F) a reactive diluent, (G) a silane coupling agent, a tertiary amine, a pigment, a solvent, and the like.

[0066] Examples of (F) reactive diluents include phenyl glycidyl ether, alkyl glycidyl ether (the alkyl group has 1 to 15 carbon atoms, preferably 11 to 15 carbon atoms), Versatic acid, glycidyl ester (R1R2R3C-COO-Gly, where R1+R2+R3=C8 to C10 alkyl group, Gly: glycidyl group), α-olefin epoxide (CH3-(CH2)n-Gly, n=11 to 13, Gly: same as above), 1,6-hexanediol diglycidyl ether (Gly-O-(CH2)6-O-Gly, Gly: same as above), neopentyl glycol diglycidyl ether (Gly-O-CH2-C(CH3)2-CH2-O-Gly, Gly: same as above), trimethylolpropane triglycidyl ether (CH3-CH2-C(CH2-O-Gly)3, Gly: same as above), Examples of reactive diluents include those having an epoxy group, such as alkylphenyl glycidyl ether (the alkyl group has 1 to 20 carbon atoms, preferably 1 to 5 carbon atoms, examples being methylphenyl glycidyl ether, ethylphenyl glycidyl ether, and propylphenyl glycidyl ether).

[0067] Among these (F) reactive diluents, monofunctional phenyl glycidyl ether, alkyl glycidyl ether, and alkylphenyl glycidyl ether have low viscosity, and therefore have an excellent dilution effect (reducing the viscosity of the paint) and can make the paint highly solid.

[0068] (F) Reactive diluents can be used alone or in combination of two or more. Examples of such reactive diluents include Epodil 759 (manufactured by Air Products Co., Ltd., alkyl (C12-C13) glycidyl ether, epoxy equivalent 285, non-volatile content 100%) and Cardolite 2513HP (manufactured by Cardolite, alkylphenol glycidyl ether, epoxy equivalent 400, non-volatile content 100%).

[0069] (G) Silane coupling agents improve the penetration of anticorrosion coating compositions into rust. (G) Silane coupling agents typically have two types of functional groups in the same molecule, contributing to improved adhesion to inorganic substrates and reduced coating viscosity, and are represented, for example, by the formula: X-Si(OR)3. In this formula, X represents a functional group or alkyl group capable of reacting with organic substances. Examples of functional groups capable of reacting with organic substances include amino groups, vinyl groups, epoxy groups, mercapto groups, halogen groups, and groups formed by adding these groups to hydrocarbon groups or groups formed by interposing an ether bond in a hydrocarbon group. OR represents a hydrolyzable group, such as a methoxy group or an ethoxy group.

[0070] Specific examples of such (G) silane coupling agents include Silicone KBM-403 (γ-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) and Silane S-510 (manufactured by Chisso Corporation). Such a silane coupling agent (G) is preferably contained in the anticorrosion coating composition (solid content) in an amount of 0.5 to 5.0 mass %, more preferably 1.0 to 3.0 mass %.

[0071] The anticorrosion coating composition of the present invention preferably contains a tertiary amine, which promotes curing. Specific examples of the tertiary amine include triethanolamine (N(C2H5OH)3), dialkylaminoethanol {[CH3(CH2) n ]2NC2H5OH, n: number of repetitions}, triethylenediamine[1,4-diazacyclo(2,2,2)octane], 2,4,6-tri(dimethylaminomethyl)phenol {[CH2N(CH3)2]3-C6H5OH}, Versamin® EH30 (manufactured by Henkel Hakusui Co., Ltd.), and Ancamine® K-54 (manufactured by Air Products Co., Ltd.).

[0072] The tertiary amine is preferably contained in the anticorrosive coating composition (solid content) in an amount of 0.1 to 3.0 mass %, more preferably 0.2 to 1.0 mass %. The pigment is not particularly limited, and known color pigments, extender pigments, anti-rust pigments, etc. Pigments are classified according to their shape, such as spherical, acicular, and fibrous, but are generally classified according to the aspect ratio, which is the ratio of the long diameter to the short diameter of the particle.

[0073] Examples of color pigments include inorganic pigments such as carbon black, titanium dioxide, red iron oxide, iron hydroxide, and ultramarine, and organic pigments such as cyanine blue and cyanine green. The color pigments can be used alone or in combination of two or more.

[0074] Examples of extender pigments include calcium carbonate, potassium feldspar, kaolin, clay, talc, bentonite, magnesium carbonate, fine silica powder, barium sulfate, wollastonite, mica powder, glass flakes, and aluminum flakes. Of these, calcium carbonate, talc, potassium feldspar, and barium sulfate are preferred. The extender pigments can be used alone or in combination of two or more.

[0075] The anti-rust pigment is not particularly limited, and may be one or a combination of two or more selected from the group consisting of zinc powder, zinc alloy powder, zinc phosphate compounds, calcium phosphate compounds, aluminum phosphate compounds, magnesium phosphate compounds, zinc phosphite compounds, calcium phosphite compounds, aluminum phosphite compounds, strontium phosphite compounds, aluminum tripolyphosphate compounds, molybdate compounds, zinc cyanamide compounds, borate compounds, nitro compounds, and composite oxides.

[0076] Furthermore, color pigments, extender pigments, and anti-rust pigments may be used in any combination. Such pigments are preferably contained in the anticorrosion coating composition (solid content) in an amount of 25 to 80 mass %, more preferably 30 to 70 mass %.

[0077] The anticorrosion coating composition of the present invention may contain, as needed, a pigment dispersant to aid in the dispersion of the pigment, a leveling agent, an anti-sagging agent, an anti-foaming agent, etc. These agents are not particularly limited, and conventionally known agents can be used.

[0078] The solvent is not particularly limited and can be appropriately selected depending on the coating workability of the anticorrosion coating composition of the present invention. Examples of solvents include xylene, toluene, MIBK (methyl isobutyl ketone), 1-methoxy-2-propanol, MEK (methyl ethyl ketone), butyl acetate, n-butanol, isobutanol, IPA (isopropyl alcohol), mineral spirits, solvent naphtha (petroleum fraction), and light aromatics. These solvents can be used alone or in combination of two or more.

[0079] <Anti-corrosion coating composition> The anticorrosion coating composition of the present invention can be prepared by mixing the above components. The corrosion-resistant coating composition of the present invention contains (A) an epoxy resin, (B) an amine curing agent, (C) a reactive butadiene acrylonitrile, and (D) magnesium oxide, and the content of (D) magnesium oxide is 5 to 15 mass % of the solid content. Preferably, the coating composition further contains (E) a non-reactive diluent. This allows the coating composition to penetrate into the rust even on rusted steel parts and to form a flexible, tough coating film on the rust. Therefore, the anticorrosive coating composition of the present invention can be suitably used on rusted surfaces.

[0080] <Anti-corrosion coating, substrate with anti-corrosion coating> The anticorrosion coating film according to the present invention (hereinafter also referred to as "the present coating film") is formed using the anticorrosion coating composition, and the substrate with the anticorrosion coating film according to the present invention (hereinafter also referred to as "the substrate with the present coating film") is a laminate having the present coating film and a substrate.

[0081] The material of the substrate is not particularly limited, and examples thereof include steel (iron, steel, ferroalloy, carbon steel, mild steel, alloy steel, etc.), non-ferrous metals (zinc, aluminum, copper, brass, zinc plating, zinc thermal spraying, etc.), and stainless steel (SUS304, SUS410, etc.).

[0082] Furthermore, when mild steel (SS400, etc.) is used as the substrate, it is desirable to adjust the surface of the substrate (e.g., adjust the arithmetic mean roughness (Ra) to about 30 to 75 μm) by polishing the surface of the substrate by grit blasting, etc., as necessary.

[0083] The substrate may be one that has been pretreated by a cleaning treatment or a blasting treatment to remove rust, dirt, paint (old paint film), etc. adhering to the substrate. Furthermore, after removing the old paint film adhering to the substrate, it is not necessary to completely remove the rust, and the anticorrosive coating composition of the present invention can be directly applied to the surface of a substrate such as a steel material on which rust remains.

[0084] Thus, even if an old coating film remains on the substrate or rust has formed thereon, according to the present invention, the anticorrosion coating composition contains the (A) epoxy resin, (B) amine curing agent, (C) reactive butadiene acrylonitrile, and (D) magnesium oxide. Therefore, even if the coating film is formed without peeling (removing) the old coating film or removing the rust, the coating film can provide the effects described above.

[0085] The substrate is not particularly limited, and the anticorrosive coating composition can be used without limitation on substrates that require corrosion resistance. However, in terms of the effectiveness of using the anticorrosive coating composition, preferable examples include (steel) structures such as ships, marine structures, plants, bridges, tanks, and containers.

[0086] The dry film thickness of the coating is not particularly limited, but is usually 10 to 150 μm, preferably 20 to 120 μm, and more preferably 30 to 100 μm, in order to obtain a coating having sufficient corrosion resistance.

[0087] The substrate with the present coating film is a laminate comprising the present coating film and a substrate, and an intermediate coating film for the purpose of further improving corrosion resistance or a top coating film excellent in weather resistance, aesthetics, etc. may be formed on the present coating film. Examples of the intermediate coating film include coating films formed from various intermediate coating paint compositions such as acrylic resin-based, epoxy resin-based, and urethane resin-based. Furthermore, examples of the top coating film include coating films formed from various top coating paint compositions such as acrylic resin-based, acrylic silicone resin-based, urethane resin-based, silicone resin-based, and fluororesin-based.

[0088] <Manufacturing method of substrate with coating film> The method for producing a substrate with a corrosion-protective coating according to the present invention (hereinafter also referred to as "the method") includes the following steps [1] and [2]. Step [1]: A step of applying the anticorrosion coating composition to a substrate Step [2]: A step of drying the anticorrosion coating composition applied to the substrate to form an anticorrosion coating film.

[0089] <Process [1]> The coating method in the step [1] is not particularly limited, and examples thereof include conventionally known methods such as spray coating such as airless spray coating and air spray coating, brush coating, roller coating, etc. Among these, spray coating is preferred because it allows for easy coating of large-area substrates such as the structure. In such coating, it is preferable to coat the resulting coating so that the dry film thickness falls within the above range.

[0090] The spray coating conditions may be adjusted as appropriate depending on the desired dry film thickness. For example, in the case of airless spray coating, the primary (air) pressure is preferably about 0.3 to 0.6 MPa, the secondary (paint) pressure is about 10 to 15 MPa, and the gun movement speed is preferably about 50 to 120 cm / sec.

[0091] When applying the anticorrosion coating composition, the viscosity of the anticorrosion coating composition may be adjusted to an appropriate value, if desired. In this case, it is preferable to use a diluent so that the paint viscosity is suitable for each coating method. For example, in the case of airless spray coating, the amount of diluent used per 100 parts by mass of the anticorrosion coating composition is preferably 1 to 30 parts by mass, more preferably 1 to 20 parts by mass.

[0092] The viscosity of the anticorrosion coating composition suitable for spray coating (a diluted composition as needed) measured at 23°C using a B-type viscometer (manufactured by Rion Co., Ltd., Model VT-06) is preferably 1,000 to 10,000 mPa·s, and more preferably 2,000 to 8,000 mPa·s.

[0093] <Process [2]> The drying conditions in step [2] are not particularly limited and may be set appropriately depending on the coating film formation method, type of substrate, application, coating environment, etc., but the drying temperature is usually 5 to 40°C, more preferably 10 to 30°C, in the case of drying at room temperature.

[0094] The drying time may be about 1 to 7 days, similar to conventional paints, but the anticorrosion coating composition can be dried preferably in 3 to 16 hours, more preferably 5 to 12 hours. [Example]

[0095] [Examples 1 to 15, Comparative Examples 1 to 8] Anticorrosion coating compositions were obtained by mixing and stirring the raw materials shown in Table 1 in the amounts shown in Table 1 using a disperser. The values ​​shown in Table 1 represent parts by mass. The obtained anticorrosion coating compositions were subjected to the following tests. The test results are shown in Table 2. Furthermore, the raw materials used in the examples and comparative examples are summarized in Table 3.

[0096] <Corrosion resistance test> The cyclic corrosion test was carried out in accordance with JIS K 5600-7-9 "Cyclic Corrosion Test Method."

[0097] The test panels were corroded steel panels with a rust thickness of 40 to 50 μm, which had been prepared by exposing unpainted steel panels outdoors for one year. After surface treatment with sandpaper (#180), the surface was cleaned with a cloth. Within 30 minutes of cleaning, the anticorrosion coating composition was applied with a brush to a dry film thickness of 100 μm, and the coating was cured under standard conditions to obtain test specimens. The resulting test panels were then cut in accordance with JIS K 5600-7-9, 7.5, a), to prepare the test panels. The test conditions were JIS K 5600-7-9 Cycle D, and the test time was 2000 hours.

[0098] After the test, the test plate was visually inspected for rust and blisters in the general areas other than the cut areas, as well as for the presence and extent of rust, blisters and rust fluid in the cut areas, and the corrosion resistance was judged according to the following evaluation criteria.

[0099] Evaluation of rust and blisters in general parts ○: No rust or blistering on the coating. △: There are some irregularities such as rust and blisters on the coating film. ×: The coating film has rust and blistering all over.

[0100] Evaluation of bulging at cut area ○: The bulge width at the cut portion is 4 mm or less. △: The bulge width of the cut portion is greater than 4 mm and less than 8 mm. ×: The bulge width of the cut portion is greater than 8 mm.

[0101] Evaluation of rust on cut areas ○: The width of the rust at the cut part is 4 mm or less. △: The rust width of the cut part is more than 4 mm and less than 8 mm. ×: The width of the rust at the cut part is greater than 8 mm.

[0102] Evaluation of rust fluid in cut areas ◎: Almost no rust is coming out of the cut area. ○: A small amount of rust is generated only from the edge of the cut portion. △: A small amount of rust is coming out from the entire cut area. ×: A large amount of rust fluid is generated from the entire cut portion.

[0103] <Adhesion test> An adhesion test was carried out in accordance with JIS K 5600-5-6 "Adhesion (cross-cut method)" on the same test plates as those used in the cyclic corrosion test.

[0104] The adhesion was evaluated according to the following evaluation criteria. ◎: Peeling area is 3% or less. ○: The peeled area is greater than 3% and equal to or less than 5%. △: Peeled area is more than 5% and 15% or less. ×: Peeled area is greater than 15%.

[0105] <Tensile test> The tensile test was carried out in accordance with Section 6, Crack Tracking Test Method, of the Quality Test Methods for Concrete Coating Materials described in the "Handbook of Steel Highway Bridges."

[0106] The anticorrosion coating composition was applied to a polypropylene resin plate using an air spray to a dry film thickness of 100 μm, and after aging at 23°C for 120 hours, it was heated at 80°C for 60 minutes and allowed to cool. The formed coating film was then peeled off from the polypropylene resin plate to obtain a free coating film. Test pieces were prepared from this free coating film using a punch, and a tensile test was performed at a gauge length of 40 mm and a test temperature of 23°C to determine the elongation.

[0107] The elongation was evaluated according to the following evaluation criteria. ○: The elongation rate is 5% or more. △: The elongation rate is 3% or more and less than 5%. ×: The elongation rate is less than 3%.

[0108] [Table 1]

[0109] Table 2

[0110] Table 3

Claims

1. 1. A corrosion-protective coating composition comprising: (A) an epoxy resin; (B) an amine curing agent; (C) a reactive butadiene acrylonitrile; and (D) magnesium oxide, the (B) amine curing agent contains (b1) phenalkamine and (b2) polyamidoamine, The magnesium oxide (D) has a BET specific surface area of ​​3.0 m 2 / g or more, The content of the (D) magnesium oxide is 5 to 15 mass% of the solid content. An anticorrosion coating composition for application to a substrate containing a rusted surface.

2. The corrosion-preventive coating composition according to claim 1, further comprising (E) a non-reactive diluent.

3. 3. The corrosion-preventive coating composition according to claim 2, wherein the non-reactive diluent (E) contains a liquid hydrocarbon resin.

4. The corrosion-preventive coating composition according to any one of claims 1 to 3, wherein the epoxy resin (A) is liquid at a temperature of 15 to 25°C.

5. The anticorrosion coating composition according to any one of claims 1 to 4, further comprising at least one selected from (F) a reactive diluent and (G) a silane coupling agent.

6. The anticorrosion coating composition according to any one of claims 1 to 5, wherein the reactive butadiene acrylonitrile (C) contains a functional group at the terminal that reacts with an epoxy group.

7. A corrosion-resistant coating film formed from the corrosion-resistant coating composition according to any one of claims 1 to 6.

8. A substrate with a corrosion-protective coating, comprising the corrosion-protective coating according to claim 7 and a substrate having a rusted surface.

9. A method for producing a substrate with a corrosion-resistant coating, comprising the following steps [1] and [2]: [1] A step of coating a substrate having a rusted surface with the anticorrosive coating composition according to any one of claims 1 to 6. [2] A step of drying the applied anticorrosion coating composition to form an anticorrosion coating film.

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