Water-based paint composition, coating film, coated substrate, and method for manufacturing a coated substrate.

Abstract

To provide an aqueous coating composition that can form a coating film with excellent corrosion resistance, chemical resistance, and impact resistance, as well as excellent adhesion to substrates, particularly non-ferrous metal substrates and stainless steel substrates, regardless of whether the coating film is formed under room temperature drying or forced drying conditions. [Solution] An aqueous paint composition comprising a first agent containing an aqueous epoxy resin (A) and a second agent containing a water-insoluble compound (B) having a structural unit derived from a chain-like polyamine.

Description

Technical Field

[0001] The present invention relates to an aqueous paint composition, a coating film, a substrate with a coating film, and a method for producing a substrate with a coating film.

Background Art

[0002] Various industrial fields, for example, (land-based) structures such as bridges, tanks, plants, (transportation) containers, etc. are usually coated with a coating film for corrosion prevention. From the viewpoints of environmental protection and safety of the working environment, in recent years, a switch from solvent-based paints to aqueous paints (aqueous paint compositions) has been desired.

[0003] As the aqueous paint composition, paint compositions such as an alkyd resin type, an epoxy ester resin type, and an epoxy-amine curing type in which an epoxy resin and an amine-based curing agent are reacted are known. For example, as a paint composition such as an epoxy-amine curing type, Patent Document 1 discloses a paint composition containing an epoxy resin, an amine-based curing agent, a silane coupling agent, water, and a pigment.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A coating film formed from a conventional epoxy-amine curing type aqueous paint composition, particularly an aqueous anti-rust paint composition, has high shrinkage stress due to a crosslinking reaction, and it has been difficult in some cases to obtain a coating film that has excellent corrosion resistance and sufficient adhesion to a substrate made of non-ferrous metal or stainless steel.

[0006] In the aforementioned structures, particularly in various fields such as building materials, mechanical structural components, chemical industry equipment components, aircraft components, and refrigerated / freezer containers, non-ferrous metals and stainless steel are used. It has been found that because the surfaces of these materials have an oxide film, their surface activity is low, and it can be difficult to firmly adhere coatings formed using conventional water-based paint compositions to these surfaces.

[0007] Furthermore, conventional epoxy-amine curing water-based paint compositions have the problem that the crosslinking properties, corrosion resistance, and adhesion to the substrate of the formed paint film are affected by the drying conditions during film formation. In particular, it has been found that there is a significant difference in the amount of heat applied during film formation between room temperature drying and forced drying, and therefore the paint films formed under each condition may exhibit different performance characteristics.

[0008] The present invention aims to provide an aqueous coating composition that can form a coating film that is excellent in corrosion resistance, chemical resistance, and impact resistance, as well as having excellent adhesion to substrates, particularly non-ferrous metal substrates and stainless steel substrates, regardless of whether the coating film is formed under room temperature drying or forced drying conditions. [Means for solving the problem]

[0009] After diligently studying methods to solve the aforementioned problems, we discovered that a water-based paint composition of a specific composition can solve these problems, and thus completed the present invention. The following are examples of the configuration of the present invention.

[0010] <1> The first component contains a water-based epoxy resin (A), The second agent contains a water-insoluble compound (B) having structural units derived from a chain-like polyamine, A water-based paint composition containing the following:

[0011] <2> The water-insoluble compound (B) has structural units derived from at least one linear polyamine selected from diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. <1> The aqueous paint composition described above.

[0012] <3> <1> or <2> A coating film formed from the aqueous coating composition described above.

[0013] <4> <3> A coated substrate having the coating film and substrate described above. <5> The aforementioned substrate is a non-ferrous metal substrate or a stainless steel substrate. <4> The coated substrate described above.

[0014] <6> A method for manufacturing a coated substrate, comprising the following steps [1] and [2]. [1] The base material, <1> or <2> A step of applying the aqueous paint composition described above. [2] A process of drying the water-based paint composition applied to the substrate to form a coating film. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an aqueous coating composition that can form a coating film that is excellent in corrosion resistance, chemical resistance, and impact resistance, as well as having excellent adhesion to substrates, particularly non-ferrous metal substrates and stainless steel substrates, regardless of whether the coating film is formed under room temperature drying or forced drying conditions. [Modes for carrying out the invention]

[0016] ≪Water-based paint composition≫ The aqueous coating composition according to the present invention (hereinafter also referred to as "this composition") is characterized by comprising a first agent containing an aqueous epoxy resin (A) (hereinafter also referred to as component (A); other components may be abbreviated similarly), and a second agent containing a water-insoluble compound (B) having a structural unit derived from a chain-like polyamine. Conventionally, compounds having structural units derived from chain polyamines have hardly been used in aqueous paint compositions because they are inferior in corrosion protection and water resistance to compounds having structural units derived from cyclic polyamines. On the other hand, since this composition contains a second agent containing component (B) together with a specific first agent, a coating film exhibiting the above effects can be easily formed. In particular, for substrates such as non-ferrous metal substrates and stainless steel substrates, on which it has been difficult to form a coating film having sufficient adhesion with conventional epoxy-amine cured aqueous paint compositions, a coating film having excellent adhesion can be formed.

[0017] This composition is suitable for members (substrates) commonly used in general industries, such as non-ferrous metals (for example, aluminum, copper, brass, zinc plating, zinc spraying), stainless steels (for example, SUS304, SUS410), etc., which are often used, and is preferably used as a paint capable of forming a coating film having excellent adhesion to the substrate, such as for refrigeration / refrigeration containers. This composition may be used for substrates requiring heavy corrosion protection, but is preferably used for substrates requiring light corrosion protection.

[0018] The first agent and the second agent are usually stored, stored, transported, etc. in separate containers, and are used after being mixed into this composition at the time of painting (for example, immediately before painting). That is, these first agent and second agent can be said to be components of a kit for preparing this composition. Further, in other words, it can be said that the above composition is a kit for an aqueous paint composition containing the first agent and the second agent. In the present invention, the first agent and the second agent are agents that can be stored after these agents are prepared until this composition is prepared. For example, mill bases described in the following examples are usually not used as the first agent or the second agent in the present invention because they are mixed with other components soon after the mill base is prepared.

[0019] This composition is not particularly limited as long as it includes the first agent and the second agent, but may contain an n-th agent (n is 3 or more) other than the first agent and the second agent as necessary. In other words, the composition may be a two-component composition consisting of the first agent and the second agent (only), or it may be a three-component or more composition containing the n agent.

[0020] In this invention, "aqueous paint composition" refers to a paint composition in which components such as component (A) and component (B) are dispersed and / or dissolved in water or a water-based medium (aqueous medium). The water content in this composition (including water that may be contained in raw materials such as component (A)) is preferably 10 to 60% by mass, more preferably 20 to 50% by mass, and even more preferably 30 to 40% by mass, based on 100% by mass of this composition.

[0021] The content of volatile organic compounds (VOCs) in this composition is preferably 150 g / L or less, more preferably 100 g / L or less, and even more preferably 80 g / L or less, in order to ensure that the composition has minimal impact on the natural environment and the painting work environment.

[0022] The VOC content in this composition can be calculated using the following formula (1), based on the composition's specific gravity, heat residue percentage (mass ratio of non-volatile components), and moisture content. The composition's specific gravity, heat residue percentage, and moisture content may be measured values ​​as shown below, or values ​​calculated from the raw materials used. VOC content (g / L) = Composition specific gravity x 1000 x (100 - heating residual fraction - moisture percentage) / 100... (1)

[0023] Composition specific gravity (g / cm 3 ): A value calculated by filling a 100 mL specific gravity cup with the composition (the composition immediately after mixing the first agent, the second agent, and (if the nth agent is included, the nth agent) under a temperature of 23°C, and weighing the mass of the composition.

[0024] Heating residue percentage (mass%): This value is calculated by measuring the heat residue (non-volatile content) and the mass of the wire after weighing 1 ± 0.1 g of the composition (the composition immediately after mixing the first agent, the second agent, and (if the nth agent is included, the nth agent) into a flat-bottomed dish, spreading it evenly using a wire of known mass, drying it at 23°C for 24 hours, and then heating it at a heating temperature of 125°C for 1 hour (under normal pressure).

[0025] In this specification, the aforementioned heating residue is referred to as the "non-volatile content of this composition." In this specification, among the raw materials that make up the first agent, the second agent, etc. (e.g., component (A)), components other than solvents and dispersion media (e.g., water) with a boiling point of less than 260°C at normal pressure in the first agent and the second agent are referred to as "solids".

[0026] Moisture content (mass%): The mass percentage of water contained in 100% by mass of this composition, as measured by the Karl Fischer method.

[0027] <First agent> The first component is not particularly limited as long as it contains an aqueous epoxy resin (A). The first agent is preferably a water-based agent containing water.

[0028] [Water-based epoxy resin (A)] The aforementioned component (A) is water, an epoxy resin that uses water as its main solvent or dispersion medium, or an epoxy resin that is miscible with water (dilutable with water). More specifically, examples include water-dispersible epoxy resins, water-soluble epoxy resins, and self-emulsifying epoxy resins. The term "epoxy resin that is miscible with water (dilutable with water)" refers to an epoxy resin that does not exhibit a significant increase in viscosity when mixed with water. In addition, it may be impossible to determine whether component (A) was an aqueous epoxy resin after it has been mixed with other components that may be included in the first agent, but even in such cases, if an aqueous epoxy resin is used as a raw material when preparing the first agent, the present invention is said to include component (A). The component (A) used in this composition (Part 1) may be one type or two or more types.

[0029] Aqueous epoxy resins can be synthesized by conventionally known methods, such as solution polymerization, suspension polymerization, emulsion polymerization, seed polymerization, miniemulsion polymerization, microemulsion polymerization, and soap-free emulsion polymerization. In addition to these, aqueous epoxy resins can also be obtained by emulsifying epoxy resins using known methods, such as phase inversion emulsification, D-phase emulsification, forced emulsification, gel emulsification, inversion emulsification, and high-pressure emulsification.

[0030] The component (A) used in the preparation of this composition (Part 1) is preferably a water-containing component, and more specifically, an epoxy resin emulsion or epoxy resin dispersion is preferred, with an epoxy resin emulsion being more preferred. Examples of epoxy resin emulsions include emulsions in which oil droplets containing epoxy resin are uniformly dispersed in an aqueous medium.

[0031] Epoxy resin emulsions can be prepared by forcibly emulsifying the epoxy resin in an aqueous medium, for example, by a phase inversion temperature emulsification method or a mechanical emulsification method. Examples of emulsifiers used include alkyl-type and alkylphenol-type nonionic surfactants; and anionic surfactants such as phosphate ester-type, alkylbenzene sulfonate-type, and sulfosuccinate-type surfactants. These emulsifiers may be used individually or in combination of two or more types.

[0032] The epoxy resin preferably has two or more epoxy groups in one molecule. The epoxy resin may be a modified epoxy resin, taking into consideration the water resistance of the coating film to be formed and the reduction of the amount of emulsifier used. This modification can be achieved, for example, by bonding the epoxy resin with one or more other compounds to introduce emulsifying segments into the molecule, thereby modifying it into a self-emulsifying epoxy resin. More specifically, this can be achieved by introducing at least one selected from polyoxyalkylene chains, hydroxyl groups, amino groups, and carboxyl groups into the epoxy resin. These modified epoxy resins may be used individually or in combination of two or more.

[0033] Examples of the epoxy resins include bisphenol-type epoxy resins, novolac-type epoxy resins (e.g., phenol novolac-type epoxy resins, cresol novolac-type epoxy resins), alicyclic epoxy resins, and aliphatic-modified epoxy resins. Among these, bisphenol-type epoxy resins are preferred because they provide a coating film with superior corrosion resistance. Examples of bisphenol-type epoxy resins include copolymers obtained using a compound having a bisphenol skeleton and an epihalohydrin, and more specifically, bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol AD-type epoxy resin, etc. Among these, bisphenol A-type epoxy resin is preferred because it yields a coating film with superior corrosion resistance. These epoxy resins may be used individually or in combination of two or more types.

[0034] The aforementioned component (A) may be a commercially available product, and examples of such commercially available products include epoxy resin emulsions such as Yukaresin NEP-1110 (manufactured by Yoshimura Oil Chemical Co., Ltd.), Adekaresin EM-101-50 (manufactured by ADEKA Corporation), Beckopox EP-387w / 52WA, Beckopox C-200 EP, Beckopox EP 384w / 53WAMP (all manufactured by Allnex), Epiclon EM-85-75W, Epiclon EM-8358 (both manufactured by DIC Corporation), and Adekaresin C-110EP (manufactured by ADEKA Corporation).

[0035] The epoxy equivalent of the solid content of component (A) is preferably 150 to 700, more preferably 400 to 600, from the viewpoint of easily forming a coating film with excellent low-temperature drying and curing properties, chemical resistance, and corrosion resistance. Note that the epoxy equivalent is the epoxy equivalent in the solid content calculated according to JIS K 7236:2001.

[0036] The epoxy resin content in 100% by mass of component (A) is preferably 35 to 100% by mass, more preferably 45 to 100% by mass, from the viewpoint of obtaining a paint composition that is superior in terms of ease of preparation, storage stability, etc. The residue of component (A) only needs to contain water, and may, if necessary, contain conventionally known components such as surfactants.

[0037] The solid content of component (A) in this composition is preferably 10 to 60 parts by mass, more preferably 10 to 50 parts by mass, even more preferably 15 to 40 parts by mass, and particularly preferably 20 to 35 parts by mass, per 100 parts by mass of the nonvolatile content of this composition, in order to easily form a coating film that is well balanced in terms of corrosion resistance and adhesion to substrates (especially non-ferrous metal substrates and stainless steel substrates).

[0038] [Other ingredients] In addition to component (A) above, the first agent may optionally contain other components such as flash rust inhibitors, pigments (e.g., extender pigments, coloring pigments, rust-preventive pigments), dispersants, film-forming aids, defoamers, leveling agents, wetting agents, thickeners, thixotropes (anti-sagging and anti-settlement agents), dryers, fibrous materials, surfactants, organic solvents, antifungal agents, preservatives, ultraviolet absorbers, light stabilizers, pH adjusters, adhesion enhancers, and plasticizers, to the extent that they do not impair the effects of the present invention. These other components may be used individually or in combination of two or more types.

[0039] The aforementioned other components can be conventionally known components, and commercially available products may also be used. When using components having reactive groups as other components, the reactivity of those reactive groups (whether they are reactive with component (A) or component (B)) should be considered when formulating each component into the first or second agent, etc.

[0040] <Flash last suppressant> Examples of flash last inhibitors include nitrites such as sodium nitrite, potassium nitrite, calcium nitrite, strontium nitrite, barium nitrite, and ammonium nitrite; benzoates such as sodium benzoate, potassium benzoate, calcium benzoate, and ammonium benzoate; phytes such as sodium phytate and potassium phytate; salts of fatty acids such as sebaciic acid and dodecanoic acid; phosphate derivatives such as alkyl phosphates and polyphosphates; tannates; metal sulfonates; N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), ethylenediaminetetraacetic acid (EDTA), and diethylenetriamine. Examples of chelating agents include amine-based chelating agents such as tetraacetic acid (DTPA), propylenediaminetetraacetic acid (PDTA), iminodiacetic acid, nitrilotriacetic acid (NTA), diethylenetriaminepentamethylenephosphonic acid (DTPMP), and their alkali metal salts; addition reaction products obtained using 4-methyl-γ-oxobenzenebutanoic acid and N-ethylmorpholine; intercalation compounds obtained by intercalating monoalkylamines, polyamines, and / or quaternary ammonium ions with layered phosphates such as aluminum dihydrogen tripolyphosphate; and hydrazine derivatives such as hydrazide compounds, semicarbazide compounds, and hydrazone compounds.

[0041] Among these, nitrites (e.g., metal salts such as sodium, potassium, and calcium, and ammonium salts) and benzoates (e.g., metal salts such as sodium, potassium, and calcium, and ammonium salts) are preferred due to their excellent flash-rust resistance and low cost. Nitrites are more preferred, and sodium nitrite is particularly preferred, because compositions exhibiting high flash-rust resistance can be easily obtained even with small amounts of use.

[0042] If the composition contains a flashlast inhibitor, the amount is preferably 0.01 to 2% by mass, more preferably 0.03 to 1% by mass, based on 100% by mass of the nonvolatile content of the composition, in order to easily obtain a composition with excellent flashlast resistance.

[0043] <Pigments> This composition may contain pigments (excluding the flash last inhibitor). Examples of the aforementioned pigments include extender pigments, coloring pigments, and rust-preventive pigments.

[0044] When this composition contains pigments, the amount of pigments is preferably 45 to 75% by mass, more preferably 50 to 70% by mass, relative to 100% by mass of the nonvolatile content of this composition, in order to easily form a coating film that is well balanced in terms of corrosion resistance, water resistance, adhesion to substrates, especially non-ferrous metal substrates and stainless steel substrates, and impact resistance.

[0045] The pigment volume concentration (PVC) in this composition is preferably 20-50%, more preferably 20-45%, even more preferably 20-40%, and particularly preferably 20-38%, in order to easily obtain a composition with superior paintability, and to easily form a coating film with superior adhesion to the substrate due to stress relaxation and superior water resistance.

[0046] The aforementioned PVC refers to the total volume concentration of pigments relative to the volume of non-volatile matter in this composition. Specifically, PVC can be calculated using the following formula (2). PVC[%] = Total volume of all pigments in this composition × 100 / Volume of non-volatile components in this composition ... Formula (2)

[0047] The volume of nonvolatile matter in the composition can be calculated from the mass and true density of the nonvolatile matter in the composition. The mass and true density of the nonvolatile matter may be measured values ​​or values ​​calculated from the raw materials used. The volume of the pigment can be calculated from the mass and true density of the pigment used. The mass and true density of the pigment may be measured values ​​or values ​​calculated from the raw materials used. For example, it can be calculated by separating the pigment from other components from the non-volatile content of the composition and measuring the mass and true density of the separated pigment.

[0048] Body pigments The aforementioned extender pigment is not particularly limited, but it is a pigment other than the coloring pigments and rust-preventive pigments listed below. Examples of the aforementioned extender pigments include conventionally known talc, mica, barium sulfate (including precipitated barium sulfate and extirpated barium sulfate), potassium feldspar, kaolin, alumina white, clay, magnesium carbonate, barium carbonate, calcium carbonate, dolomite, and silica. Among these, talc, barium sulfate, and potassium feldspar are preferred. On the other hand, it is preferable that this composition does not contain, for example, wollastonite and nepheline syenite as extender pigments, in order to easily form a coating film that exhibits the above-mentioned effects.

[0049] If this composition contains extender pigments, the amount of extender pigments is preferably 15 to 60% by mass, more preferably 20 to 55% by mass, relative to 100% by mass of the nonvolatile content of this composition, in order to easily form a coating film that is well balanced in terms of corrosion resistance, water resistance, adhesion to substrates, especially non-ferrous metal substrates and stainless steel substrates, and impact resistance.

[0050] Coloring pigments The aforementioned coloring pigment is not particularly limited, but it is a pigment other than the rust-preventive pigments listed below. Examples of the aforementioned coloring pigments include conventionally known inorganic pigments such as carbon black, titanium dioxide (titanium white), iron oxide (red iron oxide), yellow iron oxide, and ultramarine, as well as organic pigments such as cyanine blue and cyanine green. Among these, titanium white, carbon black, and red iron oxide are preferred.

[0051] If this composition contains a coloring pigment, its content is preferably 0.1 to 25% by mass, more preferably 0.5 to 20% by mass, based on 100% by mass of the non-volatile content of this composition.

[0052] Rust-preventive pigments The rust-preventive pigment is not particularly limited, but it is preferably a metal phosphate-based rust-preventive pigment, and more preferably a zinc phosphate-based, molybdenum phosphate-based, aluminum phosphate-based, or strontium phosphate-based rust-preventive pigment, as it can easily form a coating film with excellent corrosion resistance and water resistance. More specifically, examples of these rust-preventive pigments include, for example, aluminum molybdenum polyphosphate hydrate, zinc aluminum molybdenum polyphosphate hydrate, aluminum phosphomolybdate, strontium zinc phosphate silicate, zinc zinc polyphosphate hydrate, calcium strontium polyphosphate silicate hydrate, zinc phosphate, and organically modified versions thereof. Preferably, the organically modified aluminum molybdenum polyphosphate hydrate, aluminum phosphomolybdate, zinc molybdenum polyphosphate hydrate, or zinc phosphate.

[0053] When this composition contains a rust-preventive pigment, its content is preferably 0.1 to 15% by mass, more preferably 1 to 15% by mass, relative to 100% by mass of the non-volatile content of this composition, in order to easily form a coating film that is well balanced in terms of corrosion resistance, water resistance, adhesion to substrates, especially non-ferrous metal substrates and stainless steel substrates, and impact resistance.

[0054] <Dispersant> The dispersant is not particularly limited, but examples include various dispersants such as copolymers having compatible chains, such as fatty acids, polyaminos, polyethers, polyesters, polyurethanes, and polyacrylates, which have pigment-adsorbing groups (pigment affinity groups) such as carboxyl groups, phosphate groups, amino groups, groups of these salts, and ammonium bases.

[0055] If the composition contains a dispersant, the amount of dispersant is preferably 0.1 to 3% by mass, more preferably 0.1 to 2.5% by mass, relative to 100% by mass of the nonvolatile content of the composition, in order to easily form a coating film in which pigments and the like are uniformly dispersed and to easily form a coating film with excellent crack resistance.

[0056] <Antifoaming agent> To suppress the generation of foam during the preparation or application of this composition, or to break any foam generated in this composition and form a coating with desired physical properties, an antifoaming agent may be added to this composition as needed.

[0057] The aforementioned defoaming agent may be a commercially available product, and examples of such commercially available products include "BYK-320", "BYK-066N", and "BYK-1790" (all manufactured by Bic Chemie Japan Co., Ltd.), and "TEGO FOAMEX 845" and "TEGO Airex 901W" (all manufactured by Evonik).

[0058] If the composition contains an antifoaming agent, the amount is preferably 0.005 to 1% by mass, more preferably 0.01 to 0.5% by mass, relative to 100% by mass of the nonvolatile content of the composition, in order to sufficiently suppress the generation of foam and to easily form a coating film with the desired physical properties.

[0059] <Thickening agent> As the aforementioned thickening agent, conventionally known thickening agents can be used, and examples include polysaccharide-based, alkali-type thickening agents, polyurethane-associated types, polyether-associated types, polyolefin-based, and cellulose-based thickening agents.

[0060] If this composition contains a thickening agent, the amount is preferably 0.01 to 1% by mass, more preferably 0.05 to 0.8% by mass, relative to 100% by mass of the nonvolatile content of this composition, in order to sufficiently suppress dripping during painting.

[0061] <Anti-sagging agent (anti-sagging agent)> Examples of the aforementioned thixotropes include organic clay salts such as stearate salts, lecithin salts, and alkyl sulfonates of Al, Ca, and Zn; clays such as bentonite clay and hectorite clay; and organically modified products of these clays (e.g., organically modified hectorite clay); polyethylene oxide waxes; ethylene-vinyl acetate waxes; polyamide waxes; hydrogenated castor oil waxes; and synthetic fine silica. Among these, organic thixotropes such as organically modified hectorite clay, polyethylene oxide waxes, ethylene-vinyl acetate waxes, and polyamide waxes are preferred because they can easily form coatings with excellent crack resistance.

[0062] If the composition contains a thixotrope, its content is preferably 0.01 to 3.5% by mass, more preferably 0.05 to 3% by mass, based on 100% by mass of the nonvolatile content of the composition, in order to easily form a coating film with excellent crack resistance.

[0063] <Adhesion-enhancing agent> To improve the adhesion of the coating film obtained from this composition to the substrate, an adhesion promoter may be added to this composition as needed. When an adhesion promoter is added to this composition, a coating film with stronger adhesion, especially to stainless steel, can be easily formed.

[0064] The adhesion-improving agent is preferably a component other than a silane coupling agent, as it allows for the easy formation of a coating film that exhibits the aforementioned effects. Examples of silane coupling agents include epoxy group-containing silane coupling agents and amino group-containing silane coupling agents. Preferably, this composition is substantially free of silane coupling agents (i.e., no silane coupling agents are added when preparing this composition). Specifically, the content of silane coupling agents relative to 100% by mass of the non-volatile content of this composition is 0 to 0.1% by mass.

[0065] The adhesion-imparting agent is not particularly limited, but examples include copolymers such as polyester copolymers, polyalkylene copolymers, polyacrylate copolymers, and epoxy copolymers having functional groups such as amino groups and carboxyl groups. Among these, adhesion-improving agents having amino groups, such as polyalkylene copolymers having amino groups and epoxy copolymers having amino groups, are preferred because they can easily form coatings that have excellent adhesion to stainless steel.

[0066] The aforementioned adhesion-improving agent may be a commercially available product, and examples of such commercially available products include "BYK-4500", "BYK-4509", "BYK-4510", "BYK-4513" (all manufactured by BYK), and "TEGO AddBond 1270" and "TEGO AddBond DS 1300" (both manufactured by Evonik).

[0067] If this composition contains an adhesion promoter, its content is preferably 0.1 to 3% by mass, more preferably 0.3 to 1.5% by mass, relative to 100% by mass of the non-volatile content of this composition, in order to easily form a coating film with excellent adhesion to non-ferrous metals and stainless steel surfaces.

[0068] <Plasticizer> Conventional plasticizers can be used as the aforementioned plasticizer, and examples include glycol ether polymers, phthalates, trimellitic acid esters, aliphatic dibasic acid esters, phosphate esters, ricinoleic acid esters, polyesters, acetate esters, and sulfonamides.

[0069] If this composition contains a plasticizer, the amount is preferably 0.1 to 4% by mass, more preferably 0.5 to 3.5% by mass, relative to 100% by mass of the non-volatile content of this composition, in order to easily form a coating film with excellent adhesion to non-ferrous metals and stainless steel surfaces.

[0070] <water> The aforementioned component (A) may contain water, and it is preferable that component (A) contains water. However, it is preferable to further add water to the first agent in order to facilitate the preparation of the composition and improve its storage stability. The water is not particularly limited, and tap water may be used, but it is preferable to use deionized water or the like. The water content in the first agent (including water that may be contained in the raw materials such as component (A)) is not particularly limited, but is preferably 10 to 50% by mass, more preferably 20 to 40% by mass.

[0071] <Second drug> The second agent is not particularly limited as long as it includes a water-insoluble compound (B) having structural units derived from a chain-like polyamine. Since this composition contains a second agent containing component (B) along with the first agent, the coating film obtained from this composition has a particularly good balance of corrosion resistance and adhesion to substrates (especially non-ferrous metal substrates and stainless steel substrates). The second agent is preferably an organic solvent-based agent containing an organic solvent. The second agent is preferably water-free (water should not be used when preparing the second agent), and specifically, the water content relative to 100% by mass of the second agent is 0 to 0.5% by mass.

[0072] [Water-insoluble compounds having structural units derived from linear polyamines (B)] The aforementioned component (B) is a compound other than a tertiary amine (a compound having only a tertiary amino group as the amino group). The component (B) used in this composition may be one type or two or more types.

[0073] The aforementioned structural unit derived from a linear polyamine refers to a structural unit derived from a linear polyamine having at least two or more amino groups in one molecule. This structural unit may be derived from a linear polyamine or a branched polyamine, as long as it does not have a cyclic structure; however, a structural unit derived from a linear polyamine is preferred.

[0074] Furthermore, a water-insoluble compound is a compound that does not freely mix with water, and is essentially insoluble in water. Specifically, it refers to a compound in which, when mixed with water at 23°C to a solid content of 5% by mass, and allowed to stand for one day at 23°C, the resulting mixture is not homogeneous, and 50% or more of the solid content of the mixed component has separated, precipitated, or suspended.

[0075] Furthermore, in some cases, it may be impossible to determine whether component (B) was a water-insoluble compound after it has been mixed with other components that may be included in the second agent. However, even in such cases, if the water-insoluble compound (B) is used as a raw material when preparing the second agent, the second agent is said to contain component (B).

[0076] Component (B) can be, for example, a compound obtained by making the following chain-like polyamines, which are used as curing agents for epoxy compounds, insoluble in water by a known method. Methods for making the material insoluble in water include fatty acid modification (polyamidoamine) by condensation reaction using fatty acids such as dimer acid, amine adduct modification by (partial) addition reaction using epoxy compounds such as epoxy resin, Mannich reaction, Michael addition, ketimination, and aldimination.

[0077] The chain-like polyamines used as curing agents for epoxy compounds are not particularly limited as long as they are not tertiary amines (compounds having only tertiary amino groups as amino groups), but examples include amine compounds such as alkylene polyamines, polyalkylene polyamines, and other aliphatic chain-like polyamines.

[0078] Examples of the alkylene polyamine include those with the formula: "H2N-R 1 -NH2" (R 1A is a divalent chain hydrocarbon group having 1 to 12 carbon atoms. Examples of compounds represented by () include methylenediamine, ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, and trimethylhexamethylenediamine.

[0079] Examples of the aforementioned polyalkylene polyamine include those with the formula: "H2N-(C m H 2m NH) n Compounds represented by (H) (where m is an integer from 1 to 10, and n is an integer from 2 to 10, preferably an integer from 2 to 6) are examples, and specific examples include diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, pentaethylenehexamine, nonaethylenedecamine, bis(hexamethylene)triamine, and triethylene-bis(trimethylene)hexamine.

[0080] Examples of the other aliphatic chain polyamines mentioned above include tetra(aminomethyl)methane, tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2'-aminoethylamino)propane, and tris(2-aminoethyl)amine.

[0081] Component (B) preferably has structural units derived from at least one chain-like polyamine selected from diethylenetriamine, triethylenetetramine, and tetraethylenepentamine, in order to easily form a coating film with a good balance of corrosion resistance and adhesion to substrates (especially non-ferrous metal substrates and stainless steel substrates). It is more preferable that component (B) has structural units derived from at least one chain-like polyamine selected from triethylenetetramine and tetraethylenepentamine, in terms of reactivity and the low VOC content of the resulting composition. The structural units derived from the chain-like polyamine may be one type or two or more types.

[0082] Component (B) can be a modified product obtained by modifying the chain-like polyamine by the method described above, such as a fatty acid modified product such as polyamidoamine, an amine adduct with an epoxy compound, a Mannich modified product, a Michael adduct, a ketimine, and an aldimine. Among these, polyamidoamine and an amine adduct with an epoxy compound are preferred.

[0083] The active hydrogen equivalent of the solid content of component (B) is preferably 20 or more, more preferably 40 or more, preferably 1,000 or less, and more preferably 500 or less, from the viewpoint of easily forming a coating film with superior corrosion resistance.

[0084] From the standpoint of easily forming a coating film with excellent corrosion resistance, coating strength, and drying properties, it is desirable to use component (B) in an amount such that the reaction ratio calculated by the following formula (3) is preferably 0.3 to 1.5, more preferably 0.4 to 1.2.

[0085] Reaction ratio = {(Amount of solid content of component (B) / Equivalent amount of active hydrogen in the solid content of component (B)) + (Amount of solid content of component reactive with component (A) / Equivalent amount of functional groups in the solid content of component reactive with component (A))} / {(Amount of solid content of component (A) / Equivalent amount of epoxy in the solid content of component (A)) + (Amount of solid content of component reactive with component (B) / Equivalent amount of functional groups in the solid content of component reactive with component (B))} ... (3)

[0086] Here, the "component that is reactive to component (B)" in formula (3) above refers to, for example, a component that is reactive to component (B) in the other components listed below, and the "component that is reactive to component (A)" refers to, for example, a water-soluble amine compound or other component that is reactive to component (A) in the other components listed below.

[0087] The "functional group equivalent" of each component refers to the mass (g) per mole of functional group obtained by dividing the mass of 1 mole of these components by the number of moles of functional groups contained within it.

[0088] The solid content of component (B) is preferably such that it satisfies formula (3), and more preferably such that it falls within the following range. The solid content of component (B) is preferably 1.0 to 15% by mass, more preferably 2.5 to 10% by mass, based on 100% by mass of the nonvolatile content of the composition. The solid content of component (B) is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, relative to 100% by mass of the solid content of the second agent. When the content of component (B) is within the above range, a coating film with a good balance of corrosion resistance, water resistance, adhesion to substrates (especially non-ferrous metal substrates and stainless steel substrates), and impact resistance can be easily formed.

[0089] [Other ingredients] The second agent may, in addition to component (B), optionally contain other components other than component (B), to the extent that it does not impair the effects of the present invention. Examples of such other components include the same components as those listed in the section for the first agent, as well as water-soluble amine compounds and curing accelerators. These other components may be used individually or in combination of two or more types.

[0090] <Curing accelerator> To facilitate drying and curing when forming a coating film from this composition, a curing accelerator may be added to this composition as needed. Examples of the curing accelerators include polymerizable (meth)acrylate monomers and tertiary amines.

[0091] Specific examples of the aforementioned tertiary amines include triethanolamine, dialkylaminoethanol, triethylenediamine (1,4-diazabicyclo[2.2.2]octane), and 2,4,6-tris(dimethylaminomethyl)phenol. A commercially available example is "Ancamine K54" (manufactured by Evonik, 2,4,6-tri(dimethylaminomethyl)phenol).

[0092] If the composition contains a curing accelerator, the solid content of the curing accelerator is preferably 0.1 to 5% by mass relative to 100% by mass of the nonvolatile content of the composition.

[0093] <Organic solvents> This composition is an aqueous paint composition containing water, but the second component is preferably an organic solvent-based agent containing an organic solvent.

[0094] The organic solvent is preferably an organic solvent with a boiling point of less than 260°C at normal pressure. Examples include aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK), glycol ether solvents such as dipropylene glycol mono-n-butyl ether, ester solvents such as butyl acetate, alcohol solvents such as isopropanol, isobutyl alcohol, n-butanol, and methoxypropanol, and aliphatic hydrocarbon solvents such as n-hexane, n-octane, 2,2,2-trimethylpentane, isooctane, n-nonane, cyclohexane, and methylcyclohexane.

[0095] When incorporating an organic solvent into this composition, it is preferable to use an organic solvent such that the VOC content in the composition falls within the aforementioned range. The content of the organic solvent in the second agent is not particularly limited, but is preferably 0.1 to 80.0% by mass, and more preferably 5.0 to 60.0% by mass.

[0096] <Method for preparing this composition> The first agent, the second agent, and any nth agent used as needed can be prepared by mixing (kneading) the components to be incorporated into these agents. During this mixing (kneading), the components may be added and mixed all at once, or they may be added and mixed in multiple steps. This composition can be prepared by mixing (kneading) the first agent, the second agent, and an nth agent, which may be used as needed. During the mixing (kneading) process, conventionally known devices such as mixers, dispersers, and agitators can be used. Examples of such devices include dispersers, mixing / dispersing mills, mortar mixers, rolls, paint shakers, and homogenizers. Furthermore, the mixing (kneading) process may be carried out while heating, cooling, etc., depending on the season, environment, etc.

[0097] <Coating films, coated substrates> The coating film according to the present invention (hereinafter also referred to as "the coating film") is formed using the composition described above, and the coated substrate according to the composition (hereinafter also referred to as "the coated substrate") is a laminate containing the coating film and the object to be coated (substrate). The coating is preferably a corrosion-resistant coating.

[0098] The material of the base material is not particularly limited, and examples include iron and steel (e.g., iron, steel, mild steel), non-ferrous metals (e.g., aluminum, copper, brass, galvanized, zinc sprayed), and stainless steel (e.g., SUS304, SUS410). Among these, non-ferrous metals and stainless steel are preferred because they allow the effects of the present invention to be more fully realized. The substrate may have a coating film formed from a coating composition such as an alkyd resin, acrylic resin, or epoxy resin on its surface. Furthermore, when using, for example, mild steel (SS400, etc.) as the substrate, it is desirable to prepare the surface of the substrate by polishing it with grit blasting or the like (e.g., adjusting it so that the arithmetic mean roughness (Ra) is about 30 to 75 μm) as necessary. The substrate may further be a substrate that has undergone pretreatment such as cleaning or blasting to remove rust, dirt, paint (old paint film), etc., adhering to the substrate.

[0099] The aforementioned substrate is not particularly limited and can be used without restriction on substrates that require corrosion resistance and water resistance. Specific examples include (land) structures such as bridges, tanks, plants, and (transport) containers, among which the outer surface of a container is preferred.

[0100] The dry film thickness of this coating is not particularly limited, but it is usually 10 to 100 μm, preferably 20 to 60 μm, because it provides sufficient corrosion resistance, chemical resistance, and a well-balanced coating with good adhesion and impact resistance to substrates, especially non-ferrous metal substrates and stainless steel substrates.

[0101] Furthermore, the substrate with the coating film is a laminate containing the coating film and the object to be coated (substrate), and a topcoat film with superior weather resistance and aesthetics may be formed on the coating film. Examples of such topcoat films include those formed from various water-based topcoat paint compositions such as acrylic resin-based, acrylic silicone resin-based, urethane resin-based, silicone resin-based, and fluororesin-based paints.

[0102] ≪Method for manufacturing a substrate with a coating≫ The method for producing a coated substrate according to the present invention (hereinafter also referred to as "this method") includes the following steps [1] and [2]. Step [1]: A step of coating the substrate with the composition. Step [2]: A step of drying the composition applied to the substrate to form a coating film.

[0103] <Process [1]> The painting method in step [1] is not particularly limited and includes conventionally known methods such as spray painting including airless spray painting and air spray painting, brush painting, and roller painting. Among these, spray painting is preferred because it can easily paint large surface areas of substrates such as structures. When performing such painting, it is preferable to paint the coating so that the dry film thickness of the resulting coating falls within the aforementioned range.

[0104] The conditions for the spray coating described above can be adjusted as appropriate depending on the desired dry film thickness. For example, in the case of airless spray coating, a primary (air) pressure of approximately 0.3 to 0.6 MPa, a secondary (paint) pressure of approximately 10 to 15 MPa, and a gun travel speed of approximately 50 to 120 cm / second are preferred.

[0105] The viscosity of this composition suitable for spray coating is preferably 6,000 to 20,000 mPa·s, more preferably 8,000 to 12,000 mPa·s, measured at 23°C using a B-type viscometer (manufactured by Rion Co., Ltd., model VT-06).

[0106] Furthermore, when applying this composition, the viscosity may be adjusted to an appropriate level for the paint composition, if desired. Water is preferred as the diluent used for such viscosity adjustment. In this case, it is preferable to use a diluent to achieve a paint viscosity suitable for each painting method. For example, when using airless spray painting, the amount of diluent used per 100 parts by mass of the composition is preferably 1 to 30 parts by mass.

[0107] <Process [2]> The drying conditions in step [2] are not particularly limited and may be set appropriately depending on the method of forming the coating film, the type of substrate, the application, the painting environment, etc. By using this composition, it is possible to form a coating film that exhibits excellent corrosion resistance, chemical resistance, and impact resistance, as well as excellent adhesion to substrates, particularly non-ferrous metal substrates and stainless steel substrates, regardless of whether the coating film is formed under room temperature drying or forced drying conditions.

[0108] The drying temperature is typically 5 to 35°C, more preferably 10 to 30°C, for room temperature drying, and typically 30 to 90°C, more preferably 40 to 80°C, for forced drying (e.g., drying in a hot air dryer). On the other hand, the drying time varies depending on the drying method of the coating film. For room temperature drying, it is usually 1 hour to 7 days, preferably 1 to 3 days, and for forced drying, it is usually 5 to 60 minutes, preferably 10 to 30 minutes. [Examples]

[0109] The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, the amounts in the table represent "parts by mass".

[0110] [Example 1] In a container, 15.0 parts by mass of deionized water, 1.0 part by mass of dispersant, 0.1 parts by mass of flash last inhibitor, 0.4 parts by mass of defoaming agent 1, 10.0 parts by mass of coloring pigment, 15.0 parts by mass of extender pigment 1, 15.0 parts by mass of extender pigment 2, and 0.3 parts by mass of thixotrope were added, and the mixture was dispersed in a paint shaker to a particle size of 40 μm or less (according to JIS K 5600-2-5:1999) to prepare a mill base. To the prepared mill base, 36.5 parts by mass of aqueous epoxy resin A1, 0.2 parts by mass of defoaming agent 2, 1.0 part by mass of adhesion promoter, 1.0 part by mass of plasticizer, 0.2 parts by mass of thickener 1, and 4.3 parts by mass of ion-exchanged water were added, and then the mixture was mixed in a high-speed disperser to prepare the first agent. In addition, 88.0 parts by mass of water-insoluble compound B1 having structural units derived from chain-like polyamines, 3.0 parts by mass of a curing accelerator, and 9.0 parts by mass of a solvent were added to a separate container, and then mixed with a high-speed disperser to prepare the second component. The obtained first agent and second agent were mixed in a high-speed disperser in a ratio of first agent / second agent = 96 / 4 (by mass) until uniform, thereby preparing an aqueous paint composition.

[0111] [Examples 2-5 and Comparative Examples 1-3] Each aqueous coating composition was prepared in the same manner as in Example 1, except that each component listed in Table 1 was used in the amounts specified in the table.

[0112] Table 2 shows a description of each component listed in Table 1. In Tables 1 and 2, water-insoluble compounds (B) having structural units derived from linear polyamines are simply abbreviated as "water-insoluble compound B".

[0113] <Preparation of polyurethane resin-based topcoat paint> A polyurethane resin-based topcoat paint was prepared using the following method. Details of the raw materials used and their quantities in the preparation of the polyurethane resin-based topcoat paint are shown in Table 3, and a description of the raw materials used is shown in Table 4. In a container, 10 parts by mass of deionized water, 1.0 part by mass of dispersant, 0.1 part by mass of flash rust inhibitor, 0.3 parts by mass of defoaming agent 3, 18.0 parts by mass of coloring pigment, and 4.0 parts by mass of extender pigment 2 were added and dispersed in a paint shaker to a particle size of 20 μm or less (according to JIS K 5600-2-5:1999) to prepare a mill base. To the prepared mill base, 54.0 parts by mass of aqueous polyol resin, 3.7 parts by mass of film-forming aid, 0.4 parts by mass of defoaming agent 4, 0.4 parts by mass of thickener 2, and 8.1 parts by mass of ion-exchanged water were added, and then the mixture was mixed in a high-speed disperser to prepare the first agent. A polyurethane resin-based topcoat paint was prepared by mixing the first and second components (isocyanate compounds) in a ratio of 90 / 10 (by mass) using a high-speed disperser until uniform.

[0114] [Content of non-volatile components] The non-volatile content in each aqueous paint composition of the examples and comparative examples was calculated based on the heat residue rate (mass%). The results are shown in Table 1.

[0115] [PVC] The pigment volume concentration (PVC) in each aqueous paint composition of the examples and comparative examples was calculated based on formula (2) above. The results are shown in Table 1.

[0116] [VOC content] The VOC content in each aqueous coating composition of the examples and comparative examples was calculated based on formula (1) above. The results are shown in Table 1.

[0117] [Reaction ratio] The reaction ratios in each aqueous coating composition of the examples and comparative examples were calculated based on formula (3) above. The results are shown in Table 1.

[0118] [Method for preparing test specimens 1 (forced drying)] The viscosity of each aqueous paint composition in the examples and comparative examples was adjusted using deionized water so that the viscosity at 23°C, measured using a B-type viscometer (Rion Co., Ltd., model VT-06), was 1,000 mPa·s. Each water-based paint composition, after viscosity adjustment, was applied to a stainless steel plate (SUS410S, dimensions: 150mm x 70mm x 1.5mm (thickness)) using an air spray to achieve an average dry film thickness of 50μm. After drying at room temperature for 10 minutes, it was hot-air dried at 60°C for 15 minutes to form a primer film. Subsequently, the polyurethane resin-based topcoat paint was applied to the undercoat film using an air spray to achieve an average dry film thickness of 40 μm. After drying at room temperature for 10 minutes, the topcoat film was formed by hot-air drying at 60°C for 30 minutes. After forming the topcoat film, the test specimens (coated substrates) used in the various coating performance evaluation tests described later were prepared by drying them for 7 days at 23°C and 50% relative humidity.

[0119] [Method for preparing test specimens 2 (room temperature drying)] The viscosity of each aqueous paint composition in the examples and comparative examples was adjusted using deionized water so that the viscosity at 23°C, as measured using the B-type viscometer, was 1,000 mPa·s. Each water-based paint composition, after viscosity adjustment, was applied to a stainless steel plate (SUS410S, dimensions: 150mm x 70mm x 1.5mm (thickness)) using an air spray to achieve an average dry film thickness of 50μm. The paint was then dried for one day at 23°C and 50% relative humidity to form a primer film. Subsequently, the polyurethane resin-based topcoat paint was applied to the undercoat film using an air spray to achieve an average dry film thickness of 40 μm, and dried for 7 days at 23°C and 50% relative humidity to prepare test specimens (coated substrates) to be used in the various coating performance evaluation tests described later.

[0120] <Chemical resistance> Based on JIS K 5600-6-2:2016 for liquid resistance (water immersion method), each of the above test specimens was subjected to an immersion test in a 3% sulfuric acid aqueous solution and a 3% sodium hydroxide aqueous solution for 120 hours, and chemical resistance (3% acid resistance and 3% alkali resistance) was evaluated according to the evaluation criteria below. The results are shown in Table 1.

[0121] (Evaluation Criteria) ○: No blistering occurred in the coating after the chemical resistance test. △: Blisters have formed on the coating after the chemical resistance test, and the size of the blister is 2, and the quantity (density) is 3 or less, as specified in JIS K 5600-8-2:2008. ×: Blisters have formed on the coating after the chemical resistance test, and the blister size is 2 and the quantity (density) is 4 or more, or the blister size is 3 or more, as specified in JIS K 5600-8-2:2008.

[0122] <Corrosion Resistance> Scratches (scribes) of sufficient depth to expose the stainless steel plate were made on each of the aforementioned test specimens, starting 5 cm from the bottom of the long side and 1 cm from the left end of the short side, and also starting 1 cm from the bottom of the long side and 1 cm from the right end of the short side. Similarly, scratches (scribes) of sufficient depth to expose a portion of the steel plate were made, starting 5 cm from the bottom of the long side and 1 cm from the right end of the short side, and also starting 1 cm from the bottom of the long side and 1 cm from the left end of the short side. The test specimen was placed in a salt spray tester with the scribe side facing down under salt spray conditions of 5% by mass salt concentration, 35°C, and 98% relative humidity, in accordance with JIS K 5600-7-1:1999, and subjected to a salt spray test for 600 hours. The corrosion resistance was evaluated according to the evaluation criteria below. The results are shown in Table 1. In the evaluation criteria below, if both the conditions marked with △ and × are met (e.g., the rust grade as defined in JIS K 5600-8-3:2008 is Ri1 or less, and the blister size as defined in JIS K 5600-8-2:2008 is 3), the evaluation is ×.

[0123] (Evaluation Criteria) ○: No rust or blistering occurred on the coating after the salt spray test. △: Rust or blistering has occurred on the coating after the salt spray test, and the rust grade as defined in JIS K 5600-8-3:2008 is Ri1 or less (Ri1, Ri0), or the blister size is 2 and the quantity (density) is 3 or less as defined in JIS K 5600-8-2:2008. ×: Rust or blistering has occurred on the coating after the salt spray test, and the rust grade as defined in JIS K 5600-8-3:2008 is Ri2 or higher (Ri2, Ri3...), or the blister size is 2 and the quantity (density) is 4 or higher as defined in JIS K 5600-8-2:2008, or the blister size is 3 or higher.

[0124] <Adhesion> [Grid pattern adhesion test] After the corrosion resistance test, the test specimens were washed with water and then dried for one day in an environment of 23°C and 50% humidity. A cross-cut adhesion test (25 squares of 2 mm x 2 mm) was performed on the areas where saltwater had been sprayed on the test specimens and where the aforementioned scribe had not been formed, in accordance with JIS K 5600-5-6:1999. Adhesion was evaluated according to the evaluation criteria below, using the ratio (%) of the area of ​​the coating film peeled off from the stainless steel plate to 100% of the coating film area occupied by the 25 squares. The results are shown in Table 1.

[0125] (Evaluation Criteria) ○: Area of ​​peeled paint film is 15% or less ×: The area of ​​the peeled coating is greater than 15%.

[0126] [Impact resistance test] After the corrosion resistance test, the test specimen was washed with water and then dried for one day in an environment of 23°C and 50% humidity. The test specimen was then placed so that its surface was approximately perpendicular to gravity. Using an impact testing machine (manufactured by BYK-Gardener), a 2-pound weight was dropped from a height of 30 inches onto the painted surface (front) and the opposite side (back) of the test specimen, where saltwater had been sprayed and where the aforementioned scribe had not been formed. Subsequently, 1.5 cm cross-shaped cuts were made on each part of the painted surface, centered on the point where the weight fell, reaching the stainless steel plate. Transparent pressure-sensitive adhesive tape was then applied, and the tape was peeled off to measure the maximum peel width of the paint film. Impact resistance was evaluated according to the evaluation criteria below. The maximum peel width refers to the longest line drawn connecting the points where the paint film on the painted surface (front) peeled off, passing through the centers of the points where the weight fell. The results are shown in Table 1.

[0127] (Evaluation Criteria) ○: Maximum peeling width of the coating is less than 9 mm. ×: Maximum peel width of the paint film is 9 mm or more

[0128] [Creep width evaluation] After the corrosion resistance test, the test specimens were washed with water and then dried for one day in an environment of 23°C and 50% humidity. The creep width (the length between the point furthest from the scribed area and the scribed area among the areas where the coating film and the stainless steel plate had separated) was measured and evaluated according to the evaluation criteria below. Here, "evaluation target area" refers to the part of the test specimen excluding a 1 cm radius from the edge. The results are shown in Table 1.

[0129] (Evaluation Criteria) ○: Creep width is less than 2.6 mm ×: Creep width is 2.6 mm or more

[0130] [Table 1]

[0131] [Table 2]

[0132] [Table 3]

[0133] [Table 4]

[0134] This coating film was found to exhibit excellent chemical resistance, corrosion resistance, and adhesion to substrates (especially non-ferrous metal substrates and stainless steel substrates), regardless of whether it was formed under forced drying or room temperature drying conditions.

Claims

1. A water-based anticorrosive coating composition, The first component contains an aqueous epoxy resin (A), A second agent containing a water-insoluble compound (B) having structural units derived from a chain-like polyamine and an organic solvent, Includes, The water content of the second agent is 0 to 0.5% by mass relative to 100% by mass of the second agent. The content of the organic solvent in the second agent is 5.0 to 80.0% by mass. The silane coupling agent content in the aqueous anticorrosive coating composition is 0 to 0.1% by mass. The solid content of the aqueous epoxy resin (A) is 10 to 60 parts by mass per 100 parts by mass of the nonvolatile content of the aqueous anticorrosive coating composition. A water-based anticorrosive coating composition.

2. The aqueous anticorrosive coating composition according to claim 1, wherein the non-water-soluble compound (B) has structural units derived from at least one chain-like polyamine selected from diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

3. A corrosion-resistant coating film formed from the aqueous corrosion-resistant coating composition according to claim 1 or 2.

4. A coated substrate having the anticorrosive coating film and the substrate according to claim 3.

5. The coated substrate according to claim 4, wherein the substrate is a non-ferrous metal substrate or a stainless steel substrate.

6. A method for manufacturing a coated substrate, comprising the following steps [1] and [2]. [1] A step of applying the aqueous anticorrosive coating composition according to claim 1 or 2 to a substrate. [2] A process of drying the water-based anticorrosive coating composition applied to the substrate to form a coating film.

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