Rust-preventive paint composition and coating film

Abstract

The present invention provides a rust-preventive coating composition that can form a rust-preventive coating film that has good salt spray resistance even with a relatively small film thickness, and also has high weldability and low chipping resistance. [Solution] A rust-preventive paint composition is provided, comprising an alkyl silicate condensate (A), zinc powder (B), an aluminum phosphate-based rust-preventive pigment (C), and an extender pigment (D), wherein the extender pigment (D) is at least one selected from the group consisting of kaolin and gypsum (D1), at least one selected from the group consisting of mica, flat talc and glass flakes (D2), and an extender pigment (D3) which is barium sulfate, and the mass ratio ((B) / (C)) of zinc powder (B) to aluminum phosphate-based rust-preventive pigment (C) is in the range of 7.5 to 20.0.

Description

[Technical Field]

[0001] The present invention relates to a rust-preventive coating composition containing zinc powder. The present invention also relates to a coating film formed from the rust-preventive coating composition and an article having the coating film. [Background technology]

[0002] Many rust-preventive paint compositions are known to contain various rust-preventive pigments, but among them, inorganic zinc rust-preventive paint compositions containing zinc powder have excellent rust-preventive properties and are widely used as rust-preventive paints for large steel structures such as ships and bridges. This inorganic zinc rust-preventive paint composition is generally a paint containing zinc powder and a siloxane-based binder, and provides rust prevention through the sacrificial corrosion protection effect of zinc due to the electrochemical reaction between zinc in the paint film and the steel surface, and the barrier effect of oxygen and moisture by the corrosion products of zinc (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-70353 [Overview of the project] [Problems that the invention aims to solve]

[0004] Conventional anti-corrosion coating compositions used in steel processing and other applications require a coating thickness of approximately 15-20 μm to ensure corrosion resistance, particularly resistance to salt spray, resulting in high application volume and VOC emissions. On the other hand, increasing the zinc powder content is a possible way to achieve salt spray resistance while reducing the coating thickness. However, this results in insufficient weldability and chip-attack properties of the anti-corrosion coating composition. Weldability and chip-attack properties will be discussed later.

[0005] An object of the present invention is to provide a rust-preventive coating composition that can form a rust-preventive coating film that has good salt spray resistance even with a relatively small film thickness, and has high weldability and low chipping resistance. Another object of the present invention is to provide a coating film formed from the rust-preventive coating composition and an article having the coating film. [Means for solving the problem]

[0006] The present invention provides the following rust-preventive coating compositions, coatings, and articles. [1] A rust-preventive paint composition comprising an alkyl silicate condensate (A), zinc powder (B), an aluminum phosphate-based rust-preventive pigment (C), and an extender pigment (D), The aforementioned extender pigment (D) is the following extender pigments (D1) to (D3) Extender pigment (D1): At least one selected from the group consisting of kaolin and gypsum. Extender pigment (D2): At least one selected from the group consisting of mica, flattened talc and glass flakes, Extender pigment (D3): Barium sulfate At least one selected from the group consisting of, A rust-preventive paint composition in which the mass ratio ((B) / (C)) of the zinc powder (B) to the aluminum phosphate-based rust-preventive pigment (C) is in the range of 7.5 to 20.0. [2] The extender pigment (D) includes extender pigment (D1), The rust-preventive paint composition according to [1], wherein the mass ratio ((B) / (D1)) of the zinc powder (B) to the extender pigment (D1) is in the range of 3.0 to 15.0. [3] The rust-preventive paint composition according to [2], wherein the mass ratio ((C) / (D1)) of the aluminum phosphate-based rust-preventive pigment (C) to the extender pigment (D1) is in the range of 0.1 to 1.0. [4] The extender pigment (D) includes extender pigment (D2), The rust-preventive paint composition according to [1], wherein the mass ratio ((B) / (D2)) of the zinc powder (B) to the extender pigment (D2) is in the range of 3.0 to 16.0. [5] The rust-preventive paint composition according to [4], wherein the mass ratio ((C) / (D2)) of the aluminum phosphate-based rust-preventive pigment (C) to the extender pigment (D2) is in the range of 0.1 to 1.0. [6] The extender pigment (D) includes extender pigment (D3), The rust-preventive paint composition according to [1], wherein the mass ratio ((B) / (D3)) of the zinc powder (B) to the extender pigment (D3) is in the range of 0.5 to 5.0. [7] The rust-preventive paint composition according to [6], wherein the mass ratio ((C) / (D3)) of the aluminum phosphate-based rust-preventive pigment (C) to the extender pigment (D3) is in the range of 0.05 to 0.5. [8] The rust-preventive paint composition according to any one of [1] to [7], wherein the content of zinc powder (B) is 18 to 49% by mass of the solid content of the rust-preventive paint composition. [9] A rust-preventive paint composition according to any one of [1] to [8], further comprising an extender pigment other than the extender pigment (D).

[10] The alkyl silicate is given by the following formula: Si m O (m-1) X 2(m+1) [In the formula, m represents an integer from 1 to 10, and X is OR] 1 and R 2 Selected from the group consisting of, multiple X can be the same or different, R 1 and R 2 These represent alkyl groups with 1 to 5 carbon atoms, which may be identical or different. A rust-preventive paint composition as described in any of [1] to [9].

[11] A coating film formed from any of the rust-preventive coating compositions described in [1] to

[10] .

[12] An article having a coating film formed from any of the rust-preventive paint compositions described in [1] to

[10] . [Effects of the Invention]

[0007] It is possible to provide a rust preventive paint composition that can form a rust preventive coating film having good salt spray resistance even with a relatively small film thickness, and having high weldability and low chip attackability. Further, it is possible to provide a coating film formed from the rust preventive paint composition and an article having the coating film.

Embodiments for Carrying Out the Invention

[0008] <Rust preventive paint composition> The rust preventive paint composition according to the present invention (hereinafter, also simply referred to as "paint composition") is a rust preventive paint composition containing a condensate (A) of an alkyl silicate, zinc powder (B), an aluminum phosphate-based rust preventive pigment (C), and a extender pigment (D). The extender pigment (D) is at least one selected from the group consisting of extender pigments (D1) to (D3) described later. In the rust preventive paint composition according to the present invention, the mass ratio ((B) / (C) content ratio) of the zinc powder (B) to the aluminum phosphate-based rust preventive pigment (C) is within the range of 7.5 to 20.

[0009] According to the paint composition of the present invention, it is possible to form a rust preventive coating film having good salt spray resistance even with a relatively small film thickness, and having high weldability and low chip attackability. In the present specification, weldability means the property of suppressing the generation of blow holes (internal bubbles), which are welding defects, and reducing the amount of welding fumes at the welded portion of two base materials having a coating film. It can be evaluated that the lower the generation rate of blow holes and the smaller the amount of fumes, the higher the weldability.

[0010] Also, in the present specification, chip attackability means the property of causing wear (widening of the discharge port of the tip) to the tip member (chip) of the spray used for coating the rust preventive paint composition. It can be evaluated that the lower the wear caused by the discharge of the rust preventive paint composition, the lower the chip attackability. In the coating of the rust preventive paint composition, the coating amount and the pattern width are controlled by the size of the chip discharge port. When using a paint composition with high chip attackability, it becomes difficult to perform the above control, so it is necessary to replace the chip at a high frequency. Hereinafter, the components contained or that can be contained in the paint composition will be described in detail.

[0011] [1] Condensate (A) of alkyl silicate The condensate (A) of alkyl silicate is a binder. As the alkyl silicate forming the condensate (A) of alkyl silicate, the following formula: Si m O (m-1) X 2(m+1) represents an alkyl silicate.

[0012] In the above formula, m represents an integer of any one of 1 to 10, and X is OR 1 and R 2 selected from the group consisting of, and a plurality of Xs may be the same or different, and R 1 and R 2 represent an alkyl group having 1 to 5 carbon atoms, which are the same or different. The number of carbon atoms of the alkyl group is preferably 1 to 4, more preferably 1 to 3, and still more preferably 1 or 2. The coating composition can contain one or more condensates (A) of alkyl silicate.

[0013] Examples of the alkyl silicate include alkoxysilane and / or its low condensate. Examples of the alkoxysilane include tetraalkoxysilane and alkylalkoxysilane. The condensate (A) of alkyl silicate may be a partial hydrolysis condensate of alkoxysilane and / or its low condensate.

[0014] Examples of tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, and tetra-sec-butoxysilane. Examples of alkylalkoxysilanes include alkyltrialkoxysilane. Examples of alkyltrialkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane. Examples of low condensates of alkoxysilanes include methylpolysilicate and ethylpolysilicate, which are low condensates of tetraalkoxysilanes. The low condensates preferably have a degree of condensation of 3 to 10 (3 to 10 silicon atoms).

[0015] The alkyl silicate condensate (A) is preferably a partially hydrolyzed condensate of tetraalkoxysilane and / or its low condensate, and more preferably a partially hydrolyzed condensate of tetraethoxysilane and / or its low condensate.

[0016] The weight-average molecular weight (Mw) of the alkyl silicate condensate (A) is preferably 1300 to 10000, and more preferably 1400 to 8000, from the viewpoint of the curability of the paint composition, the rust prevention of the coating film, and adhesion to the substrate and the topcoat film. The Mw of the alkyl silicate condensate (A) is the weight-average molecular weight on a polystyrene basis, measured by gel permeation chromatography (GPC).

[0017] Alkyl silicate condensates (A) can be produced, for example, by conventionally known methods of partially hydrolyzing and condensing alkoxysilanes and / or their low-level condensates in an organic solvent in the presence of an appropriate amount of water and, if necessary, a catalyst such as hydrochloric acid.

[0018] The content of alkyl silicate condensate (A) in the paint composition is preferably 20 to 40% by mass, and more preferably 24 to 35% by mass, of the solid content contained in the paint composition. When the content is within the above range, it tends to form a homogeneous coating even with a relatively small film thickness. The solid content contained in the paint composition refers to the total amount of components other than solvents contained in the paint composition.

[0019] [2] Zinc powder (B) Examples of zinc powder (B) include metallic zinc powder and zinc alloy powder. Examples of zinc alloys include alloys of zinc and at least one selected from the group consisting of aluminum, magnesium, and tin. Specifically, examples include alloys of zinc and aluminum, and alloys of zinc and tin. The paint composition may contain one or more types of zinc powder (B). The shape of zinc powder (B) is not particularly limited and may be, for example, flaky or spherical.

[0020] The zinc powder (B) preferably has an average particle size in the range of 5 to 15 μm, and more preferably in the range of 6 to 12 μm. Having an average particle size within this range is advantageous from the viewpoint of corrosion resistance, weldability, and chip resistance. The average particle size can be measured using the Kozeny-Carman formula and the Blaine air permeation method.

[0021] The content of zinc powder (B) in the paint composition is preferably 18 to 49% by mass, more preferably 25 to 45% by mass, and even more preferably 30 to 40% by mass, of the solid content contained in the paint composition. Having this content within the above range is advantageous from the viewpoint of weldability and chip attack. According to the paint composition of the present invention, a rust-preventive coating film with good salt spray resistance can be formed with a relatively small film thickness, while having high weldability and low chip attack, even when the zinc powder (B) content is within the above range.

[0022] [3] Aluminum phosphate-based rust-preventive pigment (C) Examples of aluminum phosphate-based rust-preventive pigments (C) include trialuminum phosphate, aluminum orthophosphate, aluminum pyrophosphate, aluminum tripolyphosphate (aluminum triphosphate), aluminum metaphosphate, and aluminum phosphite. From the viewpoint of rust prevention, aluminum phosphate-based rust-preventive pigment (C) is preferably condensed aluminum phosphate, represented by aluminum tripolyphosphate. The paint composition may contain one or more types of aluminum phosphate-based rust-preventive pigments (C).

[0023] The content of aluminum phosphate-based rust-preventive pigment (C) in the paint composition is preferably 1.0 to 4.0% by mass, and more preferably 2.0 to 3.0% by mass, of the solid content contained in the paint composition. Having this content within the above range is advantageous from the viewpoint of rust prevention, weldability, and chip attack.

[0024] The mass ratio ((B) / (C) content ratio) of zinc powder (B) to aluminum phosphate-based rust-preventive pigment (C) in the paint composition is 7.5 to 20.0, preferably 11.0 to 20.0, more preferably greater than 11.0 and 17.0 or less, even more preferably 12.0 to 17.0, still more preferably 12.0 to 16.0, and particularly preferably 13.0 to 15.0. Having this mass ratio within the above range is advantageous from the viewpoint of rust prevention, weldability, and chip attack. From the viewpoint of achieving both rust prevention and weldability and chip attack, it is preferable that the mass ratio is within the above range and that the content of zinc powder (B) is 18 to 49% by mass of the solid content contained in the paint composition.

[0025] [4] Extender pigments (D) The extender pigment (D) is at least one selected from the group consisting of the extender pigments (D1) to (D3) listed below. Extender pigment (D1): At least one selected from the group consisting of kaolin and gypsum. Extender pigment (D2): At least one selected from the group consisting of mica, flattened talc, and glass flakes. Extender pigment (D3): Barium sulfate

[0026] The paint composition may contain one or more extender pigments (D). The extender pigment (D) may consist only of extender pigment (D1), only of extender pigment (D2), only of extender pigment (D3), a combination of extender pigment (D1) and extender pigment (D2), a combination of extender pigment (D1) and extender pigment (D3), a combination of extender pigment (D2) and extender pigment (D3), or a combination of extender pigment (D1), extender pigment (D2), and extender pigment (D3). Preferably, the extender pigment (D) consists only of extender pigment (D1), only of extender pigment (D2), or only of extender pigment (D3). Note that all extender pigments belonging to extender pigment (D2) are flat pigments.

[0027] When the extender pigment (D) contains extender pigment (D1), the mass ratio of zinc powder (B) to extender pigment (D1) ((B) / (D1) content ratio) is preferably 3.0 to 15.0, more preferably 3.0 to 10.0, and even more preferably 4.0 to 6.0. Having this mass ratio within the above range is advantageous from the viewpoint of rust prevention, weldability, and chip attack.

[0028] When the extender pigment (D) contains extender pigment (D1), the mass ratio of the aluminum phosphate-based rust-preventive pigment (C) to the extender pigment (D1) ((C) / (D1) content ratio) is preferably 0.1 to 1.0, more preferably 0.2 to 0.5, and even more preferably 0.2 to 0.4. Having this mass ratio within the above range is advantageous from the viewpoint of rust prevention, weldability, and chip attack.

[0029] When the extender pigment (D) contains extender pigment (D2), the mass ratio of zinc powder (B) to extender pigment (D2) ((B) / (D2) content ratio) is preferably 3.0 to 16.0, more preferably 3.0 to 10.0, and even more preferably 4.0 to 7.0. Having this mass ratio within the above range is advantageous from the viewpoint of rust prevention, weldability, and chip attack.

[0030] When the extender pigment (D) contains extender pigment (D2), the mass ratio of the aluminum phosphate-based rust-preventive pigment (C) to the extender pigment (D2) ((C) / (D2) content ratio) is preferably 0.1 to 1.0, more preferably 0.2 to 0.7, and even more preferably 0.2 to 0.5. Having this mass ratio within the above range is advantageous from the viewpoint of rust prevention, weldability, and chip attack.

[0031] When the extender pigment (D) contains extender pigment (D3), the mass ratio of zinc powder (B) to extender pigment (D3) ((B) / (D3) content ratio) is preferably 0.5 to 5.0, more preferably 0.7 to 5.0, and even more preferably 1.0 to 5.0. Having this mass ratio within the above range is advantageous from the viewpoint of rust prevention, weldability, and chip attack.

[0032] When the extender pigment (D) contains extender pigment (D3), the mass ratio of the aluminum phosphate-based rust-preventive pigment (C) to the extender pigment (D3) ((C) / (D3) content ratio) is preferably 0.05 to 0.5, more preferably 0.05 to 0.4, and even more preferably 0.1 to 0.35. Having this mass ratio within the above range is advantageous from the viewpoint of rust prevention, weldability, and chip attack.

[0033] The content of the extender pigment (D) in the paint composition is preferably 2.0 to 40.0% by mass, and more preferably 5.0 to 35.0% by mass, of the solid content contained in the paint composition. Having this content within the above range is advantageous from the viewpoint of rust prevention, weldability, and chip attack.

[0034] [5] Other ingredients The paint composition may contain other components as needed. Other components include binders other than alkyl silicate condensates (A), metal powders other than zinc powder (B), rust-preventive pigments other than aluminum phosphate-based rust-preventive pigments (C), extender pigments other than extender pigments (D), coloring pigments, anti-settling agents, thickeners, anti-sagging agents, viscosity modifiers, defoaming agents, dispersants, color separation inhibitors, plasticizers, UV absorbers, organic solvents, water, etc. The paint composition may contain one or more other components.

[0035] In one preferred embodiment of the coating composition, the binder consists solely of an alkyl silicate condensate (A).

[0036] Examples of metal-based powders other than zinc powder (B) include Fe-Si powder, Fe-Mn powder, Fe-Cr powder, magnetite powder, and iron phosphide powder. In a preferred embodiment of the paint composition, the paint composition does not contain metal-based powders other than zinc powder (B) (except for those belonging to extender pigments).

[0037] Examples of rust-preventive pigments other than aluminum phosphate-based rust-preventive pigment (C) include zinc phosphate compounds, calcium phosphate compounds, magnesium phosphate compounds, zinc phosphite compounds, calcium phosphite compounds, strontium phosphite compounds, zinc cyanamide compounds, zinc molybdate compounds, borate compounds, and nitro compounds. In one preferred embodiment of the paint composition, the rust-preventive pigment consists solely of aluminum phosphate-based rust-preventive pigment (C).

[0038] Examples of extender pigments other than extender pigment (D) include zinc oxide, feldspar (potassium feldspar, soda feldspar, etc.), silica, colloidal silica, aluminum oxide, zirconium silicate, calcium carbonate, magnesium carbonate, calcium sulfate, wollastonite, and diatomaceous earth.

[0039] The content of extender pigments other than extender pigment (D) in the paint composition is preferably 0.5 to 45.0% by mass, and more preferably 0.5 to 35.0% by mass, of the solid content contained in the paint composition. Having this content within the above range is advantageous from the viewpoint of rust prevention, weldability, and chip attack.

[0040] Examples of coloring pigments include titanium dioxide, zircon oxide, basic lead sulfate, tin oxide, carbon black, white lead, graphite, zinc sulfide, chromium oxide, yellow nickel titanium, yellow chromium titanium, yellow iron oxide, red iron oxide (red iron oxide), black iron oxide and other iron oxides, azo-based red and yellow pigments, chromium yellow, phthalocyanine green, phthalocyanine blue, ultramarine blue, and quinacridone.

[0041] Examples of anti-settling agents include organic bentonite-based anti-settling agents, polyethylene oxide-based anti-settling agents, fumed silica-based anti-settling agents, and amide-based anti-settling agents. Examples of anti-sagging agents include amide-based anti-sagging agents, bentonite-based anti-sagging agents, polyethylene wax, hydrogenated castor oil wax, long-chain fatty acid ester polymers, polycarboxylic acids, and silica microparticle-based anti-sagging agents.

[0042] Examples of viscosity modifiers include inorganic viscous agents such as layered silicates (silicate minerals), halide minerals, oxide minerals, carbonate minerals, borate minerals, sulfate minerals, molybdate minerals, tungstate minerals, phosphate minerals, arsenate minerals, and vanadate minerals. Examples of defoaming agents include silicone-based defoaming agents and non-silicone-based defoaming agents.

[0043] Examples of plasticizers include phthalate esters such as dioctyl phthalate (DOP), dimethyl phthalate, dicyclohexyl phthalate, and diisodecyl phthalate (DIDP); aliphatic dibasic acid esters such as isobutyl adipate and dibutyl sebacate; glycol esters such as diethylene glycol dibenzoate and pentaerythritol alkyl esters; phosphate esters such as tricresyl phosphate, triaryl phosphate, and trichloroethyl phosphate; epoxy compounds such as epoxy soybean oil and epoxy octyl stearate; organotin compounds such as dioctyl staghorn laurylate and dibutyl staghorn laurylate; trioctyl trimellitic acid and triacetylene; and non-curable thermoplastic resins such as polyvinyl butyral resin.

[0044] Examples of organic solvents include hydrocarbons such as toluene, xylene, ethylbenzene, cyclopentane, octane, heptane, cyclohexane, white spirit, Solvesso 100, Solvesso 150, Solvesso 200, Swazole 1800, Swazole 310, Isopar G, Exon Naphtha No. 5, and Exon Naphtha No. 6; ethers such as dioxane, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and butyl cellosolve; esters such as butyl acetate, propyl acetate, benzyl acetate, ethylene glycol monomethyl ether acetate, and ethylene glycol monoethyl ether acetate; ketones such as ethyl isobutyl ketone and methyl isobutyl ketone; and alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and t-butanol.

[0045] [6] Forms and uses of paint compositions The paint composition may be a sachet-type paint composition comprising, for example, a first agent containing an alkyl silicate condensate (A) and a second agent containing zinc powder (B), an aluminum phosphate-based rust-preventive pigment (C), and an extender pigment (D). The first and second agents may each contain organic solvents, water, and other volatile components. If other components are included as described above, these other components may be included in either the first or second agent, or in both.

[0046] In one embodiment, the sachet-type paint composition consists of a liquid first agent and a liquid, paste, or powder second agent. In another embodiment, the sachet-type paint composition consists of a liquid first agent and a paste second agent. The first and second agents are usually stored, transported, etc., in separate containers and mixed immediately before use. The first and second agents can be prepared by mixing the components to be contained in each.

[0047] The mixing of the first and second components, as well as the mixing of the first and second components, can be carried out using a disperser, mixing / dispersion mill, mortar mixer, roll, paint shaker, homogenizer, etc.

[0048] The paint composition is suitable as a primary rust-preventive paint composition. The paint composition of the present invention is suitable as a rust-preventive paint composition used in steel processing processes and the like because it can form a rust-preventive coating film with high rust prevention, high weldability and low chipping resistance.

[0049] [7] Coatings and articles having coatings The coating film according to the present invention is a coating film (rust-preventive coating film) formed from the above-mentioned paint composition according to the present invention. The coating film thickness is usually 30 μm or less, preferably 5 to 20 μm, more preferably 5 to 15 μm, even more preferably 5 to 13 μm, and still more preferably 5 to 10 μm. According to the paint composition of the present invention, even with a film thickness of 15 μm or less, and even more preferably 10 μm or less, it is possible to form a rust-preventive coating film that has good salt spray resistance, high weldability, and low chipping resistance.

[0050] Articles on which a coating film is formed include ships, offshore structures, bridges, and land-based tanks. The substrate on which the coating film is formed is preferably steel. The substrate may be blast-treated.

[0051] A coating film can be formed by applying a coating composition to a substrate and then drying and curing the applied coating composition. Conventional methods for applying the coating composition include, for example, spraying, brushing, rolling, and dipping. In the case of spraying, for example, the coating film thickness can be controlled by the discharge pressure and the size of the nozzle tip. According to the coating composition of the present invention, the tip wear is low, thus reducing the frequency of tip replacement.

[0052] The coated paint composition can be dried and cured at a temperature of, for example, 5 to 40°C, preferably 10 to 30°C. If necessary, drying and curing may be carried out while heating. The coated paint composition hardens through a hydrolysis condensation reaction caused by water in the paint composition or moisture in the air. [Examples]

[0053] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0054] <Production Example A1: Preparation of Alkyl Silicate Condensate Solution> 2.1 parts by mass of pure water, 0.01 parts by mass of 2N hydrochloric acid, and 4.7 parts by mass of isopropyl alcohol were placed in container A and mixed. Next, 13.9 parts by mass of ethyl silicate ("Ethyl Silicate 40" manufactured by Colcoat Co., Ltd.) and 18.4 parts by mass of isopropyl alcohol were placed in a polymerization vessel and the temperature was raised to 40°C. Then, the mixture from container A was added dropwise to the polymerization vessel over 1 hour. After the dropwise addition was complete, the mixture was stirred at 40°C for 1 hour. After 1 hour of stirring, the temperature was raised to 60°C, and 3.9 parts by mass of isopropyl alcohol and 0.01 parts by mass of plasticizer (polyvinyl acetal resin, "Eslec B BL-1" manufactured by Sekisui Chemical Co., Ltd.) were added. The mixture was stirred for 13 to 20 hours while maintaining the temperature at 60°C to obtain a solution of alkyl silicate condensate (A). This solution is referred to as "condensate solution A1".

[0055] The weight-average molecular weight (Mw) of the alkyl silicate condensate contained in condensate solution A1 was 3,500. Mw is the weight-average molecular weight in polystyrene terms, measured by GPC. The measurement conditions were as follows: Equipment: Tosoh Corporation "HLC-8220GPC" Column: TSKgel SuperHZM-M × 2 Eluent: Tetrahydrofuran Measurement temperature: 35℃ Detector: RI

[0056] <Preparation Examples A2-A9: Preparation of Alkyl Silicate Condensate Solutions> A solution of alkyl silicate condensate (A) was obtained in the same manner as in Production Example A1, except that the type and amount of ethyl silicate, the amount of plasticizer, and the presence or absence of colloidal silica ("Methanol Silica Sol" manufactured by Nissan Chemical Corporation, silica concentration 30% by mass) were changed. The solutions obtained in Production Examples A2 to A9 are referred to as "condensate solutions A2 to A9," respectively. Tables 1 and 2 show the proportions (parts by mass) of the components (excluding organic solvents) used in the preparation of condensate solutions A1 to A9. Tables 1 and 2 also show the Mw of the alkyl silicate condensates contained in condensate solutions A1 to A9.

[0057] [Table 1]

[0058] [Table 2]

[0059] The alkyl silicates used in the above manufacturing examples are represented by the following chemical formulas. Ethyl silicate 40: Si5O4(OEt) 12 (Manufactured by Colcoat Co., Ltd.) Ethyl silicate 28: Si(OEt)4 (manufactured by Colcoat Co., Ltd.) Ethyl silicate 28P:Si(OEt)4 (manufactured by Colcoat Co., Ltd.)

[0060] <Manufacturing Example B1: Preparation of Zinc Powder-Containing Paste> 1.3 parts by mass of aluminum dihydrogen tripolyphosphate as an aluminum phosphate-based rust-preventive pigment (C), 5.3 parts by mass of kaolin as an extender pigment (D), 0.3 parts by mass of zinc oxide and 13.9 parts by mass of feldspar as other extender pigments, 2.3 parts by mass of iron oxide and 0.8 parts by mass of titanium dioxide as coloring pigments, 0.6 parts by mass of a settling inhibitor, 2.2 parts by mass of xylene and 11.2 parts by mass of isobutanol as organic solvents were placed in a container, glass beads were added, and the mixture was dispersed using a disperser for 20 minutes. Next, 19.1 parts by mass of spherical zinc powder as zinc powder (B) was added, and the mixture was shaken for a further 5 minutes to disperse the components. After that, the glass beads were removed to obtain a zinc powder-containing paste (hereinafter referred to as "paste"). This paste is called "Paste B1".

[0061] <Manufacturing Examples B2-B36: Preparation of Zinc Powder-Containing Paste> The paste was obtained in the same manner as in Manufacturing Example B1, except that the types and amounts of the ingredients were changed as shown in Tables 3 to 7. The pastes obtained in Manufacturing Examples B2 to B36 are referred to as "Pastes B2 to B36," respectively.

[0062] The details of the ingredients used in manufacturing examples B1 to B36 are as follows: • Zinc powder: "F-500" manufactured by Honjo Chemical Co., Ltd., with an average particle size of 7.5 μm obtained by the Blaine air permeation method. • Kaolin: BASF's "SATINTONE W / Whitetex" • Gypsum: "TA-85N" manufactured by Noritake Co., Limited. • Mica: KMPM manufactured by Kaolin (Malaysia) Sdn Bhd. • Glass flakes: "Microglass (registered trademark) Glass Flakes (registered trademark) RCF-140" manufactured by Nippon Sheet Glass Co., Ltd. • Flattened talc: Imerys "STEASHIELD10" ·Precipitated barium sulfate: “BARIUM SULPHATE PRECIPITATED NT-BS” manufactured by Beijing Yingda Technology Co., Ltd. • Barite Powder: "Barite Powder FBA" manufactured by Fuji Talc Industries Co., Ltd. • Feldspar: "FELDSPAR PG-F7 BL" manufactured by Sibelco Minerals (Thailand) Company Limited. • Iron oxide: Bayferrox 303T manufactured by Lanxess Corporation • Titanium dioxide: "Typeque CR-50" manufactured by Ishihara Sangyo Co., Ltd. • Anti-settling agent: "BP-127A" manufactured by Zhejiang Huate New Material Co., Ltd.

[0063] <Examples 1-28, Comparative Examples 1-8: Preparation of rust-preventive coating compositions> Rust-preventive coating compositions were obtained by mixing one of the condensate solutions A1 to A9 with one of the pastes B1 to B36, according to the descriptions in Tables 3 to 7. The numerical values ​​in the "Components" column of Tables 3 to 7 represent the amount added, and the unit is parts by mass.

[0064] The following values ​​for the obtained rust-preventive coating compositions are also shown in Tables 3 to 7. • Mass ratio of zinc powder (B) to aluminum phosphate-based rust-preventive pigment (C) ((B) / (C) mass ratio) • Mass ratio of zinc powder (B) to extender pigment (D1) ((B) / (D1) mass ratio) • Mass ratio of zinc powder (B) to extender pigment (D2) ((B) / (D2) mass ratio) • Mass ratio of zinc powder (B) to extender pigment (D3) ((B) / (D3) mass ratio) • Mass ratio of aluminum phosphate-based rust-preventive pigment (C) to extender pigment (D1) ((C) / (D1) mass ratio) • Mass ratio of aluminum phosphate-based rust-preventive pigment (C) to extender pigment (D2) ((C) / (D2) mass ratio) • Mass ratio of aluminum phosphate-based rust-preventive pigment (C) to extender pigment (D3) ((C) / (D3) mass ratio) • Zinc powder content (mass%) in the solid content of the rust-preventive paint composition ((B) / solid content)

[0065] [evaluation] (1) Evaluation of salt spray resistance (corrosion prevention) Test plates were prepared in accordance with the descriptions in Patent Documents 1

[0087] to

[0088] above, and a salt spray test was conducted. However, a rust-preventive coating was formed on the blasted surface of a grid blast-treated plate (JIS G 3101, SS400, dimensions: 150 × 60 × 3.2 mm), and the thickness of the rust-preventive coating was set to 10 μm. The rust-preventive paint composition was applied using an air spray (gravity-feed spray gun with 400cc cup set). Furthermore, the salt spray test was conducted for 150 hours. After the test, the ratio (%) of the rusted area to the total area of ​​the test plate was determined, and the rust condition was evaluated according to the following criteria. The evaluation results are shown in Tables 3 to 7. A smaller ratio of rusted area indicates higher salt spray resistance. 10: No rusting occurs, or the rusted area is 0.01% or less of the total surface area of ​​the test plate. 9: The rusted area is greater than 0.01% but less than or equal to 0.03% of the total surface area of ​​the test plate. 8. The rusted area is greater than 0.03% but less than or equal to 0.1% of the total surface area of ​​the test plate. 7. The rusted area is greater than 0.1% but less than or equal to 0.3% of the total surface area of ​​the test plate. 6. The rusted area is greater than 0.3% but less than or equal to 1% of the total surface area of ​​the test plate. 5. The rusted area is greater than 1% but less than or equal to 3% of the total surface area of ​​the test plate. 4. The rusted area is greater than 3% but less than or equal to 10% of the total surface area of ​​the test plate. 3. The rusted area is greater than 10% but less than or equal to 16% of the total surface area of ​​the test plate. 2: The rusted area is greater than 16% but less than or equal to 33% of the total surface area of ​​the test plate. 1: The rusted area is greater than 33% but less than or equal to 50% of the total surface area of ​​the test plate. 0: The rusted area is greater than 50% but less than or equal to 100% of the total surface area of ​​the test plate.

[0066] (2) Evaluation of weldability (2-1) Evaluation of blowhole occurrence rate A test plate with a 10 μm thick rust-preventive coating was prepared by applying a rust-preventive paint composition to the blasted surface of a grit blast-treated plate (JIS G 3101, SM490A, dimensions: t16 × w100 × L300 mm) under the same painting conditions as in (1) above. Overlap fillet welding was performed using the painted test plate. A flux-cored wire for fillet welding (Kobe Steel, Ltd. "MX-Z200", wire diameter 1.2 mm) was used as the welding material.

[0067] The welded joint was fractured along the weld line using a press, and the total area of ​​blowholes (width × length × number of blowholes) on the fracture surface was divided by the evaluation area to calculate the blowhole occurrence rate (%). The blowhole occurrence rate was then evaluated according to the following criteria. The evaluation results are shown in Tables 3 to 7. A lower blowhole occurrence rate indicates higher weldability. A: Blowhole occurrence rate is less than 8% B: Blowhole occurrence rate is 8% or more but less than 10% C: Blowhole occurrence rate is 10% or higher

[0068] (2-2) Evaluation of fume generation Using rolled steel for welded structures (SM490A, size (mm): t12 x w75 x L430), the amount of fume generated was measured in accordance with JIS Z 3930:2013 "Method for measuring the amount of fume generated in arc welding and method for sampling fumes for analysis".

[0069] From the above measurements, the amount of fume generated per second (mg / s) during welding was determined, and the amount of fume generated was evaluated according to the following criteria. The evaluation results are shown in Tables 3 to 7. Lower fume generation indicates higher weldability. A: The amount of fume generated per second during welding (mg / s) is 8.0 or less. B: Welding fume generation rate per second (mg / s) is greater than 8.0 and less than or equal to 8.5. C: Welding fume generation rate per second (mg / s) exceeds 8.5

[0070] (3) Evaluation of chip attack A rust-preventive paint composition was spray-coated using an air sprayer at a discharge pressure of 0.6 MPa for 8 hours continuously. After the test, the magnification of the nozzle tip (100 × nozzle area after the test / nozzle area before the test (%)) was measured, and the tip aggressiveness was evaluated according to the following criteria. The evaluation results are shown in Tables 3 to 7. A smaller magnification indicates lower tip aggressiveness. A: Magnification ratio of 110% or less B: Magnification ratio between 110% and 120% C: Magnification exceeds 120%

[0071] [Table 3]

[0072] [Table 4]

[0073] [Table 5]

[0074] [Table 6]

[0075] [Table 7]

Claims

1. A rust-preventive paint composition comprising an alkyl silicate condensate (A), zinc powder (B), an aluminum phosphate-based rust-preventive pigment (C), and an extender pigment (D), The aforementioned extender pigment (D) is the following extender pigments (D1) to (D3) Extender pigment (D1): At least one selected from the group consisting of kaolin and gypsum. Extender pigment (D2): At least one selected from the group consisting of mica, flattened talc and glass flakes, Extender pigment (D3): Barium sulfate At least one selected from the group consisting of, A rust-preventive paint composition in which the mass ratio ((B) / (C)) of the zinc powder (B) to the aluminum phosphate-based rust-preventive pigment (C) is in the range of 7.5 to 20.

0.

2. The extender pigment (D) includes extender pigment (D1), The rust-preventive coating composition according to claim 1, wherein the mass ratio ((B) / (D1)) of the zinc powder (B) to the extender pigment (D1) is in the range of 3.0 to 15.

0.

3. The rust-preventive paint composition according to claim 2, wherein the mass ratio ((C) / (D1)) of the aluminum phosphate-based rust-preventive pigment (C) to the extender pigment (D1) is in the range of 0.1 to 1.

0.

4. The extender pigment (D) includes extender pigment (D2), The rust-preventive paint composition according to claim 1, wherein the mass ratio ((B) / (D2)) of the zinc powder (B) to the extender pigment (D2) is in the range of 3.0 to 16.

0.

5. The rust-preventive paint composition according to claim 4, wherein the mass ratio ((C) / (D2)) of the aluminum phosphate-based rust-preventive pigment (C) to the extender pigment (D2) is in the range of 0.1 to 1.

0.

6. The extender pigment (D) includes extender pigment (D3), The rust-preventive paint composition according to claim 1, wherein the mass ratio ((B) / (D3)) of the zinc powder (B) to the extender pigment (D3) is in the range of 0.5 to 5.

0.

7. The rust-preventive paint composition according to claim 6, wherein the mass ratio ((C) / (D3)) of the aluminum phosphate-based rust-preventive pigment (C) to the extender pigment (D3) is in the range of 0.05 to 0.

5.

8. The rust-preventive paint composition according to claim 1, wherein the content of the zinc powder (B) is 18 to 49% by mass of the solid content of the rust-preventive paint composition.

9. The rust-preventive paint composition according to claim 1, further comprising extender pigments other than the extender pigment (D) mentioned above.

10. The alkyl silicate is given by the following formula: Yes ｍ O （ｍ－１） X ２（ｍ＋１） [In the formula, m represents an integer from 1 to 10, and X represents OR] １ and R ２ Selected from the group consisting of, multiple X may be the same or different, R １ and R ２ These represent alkyl groups having 1 to 5 carbon atoms, which may be the same or different. The rust-preventive paint composition according to claim 1, as represented by [the specified formula].

11. A coating film formed from the rust-preventive coating composition according to any one of claims 1 to 10.

12. An article having a coating film formed from the rust-preventive coating composition according to any one of claims 1 to 10.

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