Metal surface treatment agent

Abstract

Providing a metal surface treatment agent capable of high-temperature firing and capable of imparting high corrosion resistance to a metal substrate. A metal surface treatment agent comprising a silicate compound (A); an alkali metal salt (B) other than a silicate compound, other than a vanadium compound, and other than a zirconium compound; a vanadium compound (C); a zirconium compound (D); and water, wherein the silicon element content is 10 mass% or more with respect to the total solid content of the metal surface treatment agent. Preferably, the silicate compound (A) is an alkali metal silicate.

Description

Technology Field

[0001] The present invention relates to a metal surface treatment agent. Background Technology

[0002] Traditionally, zinc phosphate treatment and zirconium-based chemical conversion treatments have been known as technologies for imparting corrosion resistance to metal substrates such as steel. Although zinc phosphate treatment is used as a chemical conversion treatment for paint substrates, it utilizes phosphorus, an eutrophication element, and nickel, which poses a carcinogenic risk, as coating components; consequently, there is a recent tendency to avoid its use from the perspective of environmental protection and its impact on the human body.

[0003] Zirconium-based chemical conversion treatment is a technology that has been applied to existing aluminum-based materials, and the reality is that there is still room for improvement regarding the technology for imparting high corrosion resistance to steel materials. Prior art literature

[0004] Special Publication No. 2020-186456 The problem to be solved

[0005] The technology described in Patent Document 1 relates to a surface-treated steel plate, and the surface treatment film includes an acrylic resin emulsion. In reality, when the main component of the surface treatment film includes a resin component such as an acrylic resin emulsion, it is difficult to raise the material temperature reached during firing (PMT) to a high temperature of, for example, 200°C or higher, so sufficient heat resistance and durability of the coating film are not obtained, and sufficient corrosion resistance is not obtained after painting.

[0006] The present invention is based on the above idea and aims to provide a metal surface treatment agent capable of high-temperature firing and imparting high corrosion resistance to a metal substrate. means of solving the problem

[0007] (1) The present invention relates to a metal surface treatment agent comprising a silicate compound (A); an alkali metal salt (B) other than the silicate compound, other than the vanadium compound, and other than the zirconium compound; a vanadium compound (C); a zirconium compound (D); and water, wherein the silicon element content is 10 mass% or more with respect to the total solid content of the metal surface treatment agent.

[0008] (2) The above silicic acid compound (A) is a metal surface treatment agent described in (1) which is a silicate of an alkali metal.

[0009] (3) A metal surface treatment agent described in (1) or (2) having a molar ratio (M / Si) of an alkali metal element (M) to a silicon element (Si) contained in the solid portion of the metal surface treatment agent to be 0.5 to 1.2.

[0010] (4) A metal surface treatment agent described in any one of (1) to (3), wherein the content of vanadium element is 0.1 to 10 mass% and the content of zirconium element is 0.1 to 10 mass% with respect to the total solid content of the metal surface treatment agent.

[0011] (5) A metal surface treatment agent described in any one of (1) to (4) further comprising a chelating agent (E).

[0012] (6) A metal surface treatment film cured from any one of (1) to (5).

[0013] (7) Surface-treated metal having a metal surface treatment film as described in (6). Effects of the invention

[0014] According to the present invention, a metal surface treatment agent capable of high-temperature firing and capable of imparting high corrosion resistance to a metal substrate can be provided. Specific details for implementing the invention

[0015] Hereinafter, a metal surface treatment agent according to an embodiment of the present invention will be described. The present invention is not limited to the embodiments described below.

[0016] Metal Surface Treatment Agent

[0017] The metal surface treatment agent according to the present embodiment comprises a silicate compound (A); an alkali metal salt (B) other than a silicate compound, other than a vanadium compound, and other than a zirconium compound; a vanadium compound (C); a zirconium compound (D); and water. In addition, it is preferable to contain a chelating agent (E).

[0018] (Silicate compound(A))

[0019] The silicate compound (A) is the main component of the film formed by the metal surface treatment agent. By making the main component of the film an inorganic compound, the silicate compound (A), high-temperature firing of the film becomes possible. Specific examples of the silicate compound (A) include alkali metal silicates, colloidal silica, alkyl silicate compounds, hydrolysis products of alkyl silicate compounds, and condensation products of alkyl silicate compounds, but from the perspective of corrosion resistance, it is preferable that the silicate compound (A) be an alkali metal silicate. Examples of alkali metal silicates include alkali metal salts of orthosilicic acid such as lithium orthosilicate, sodium orthosilicate, and potassium orthosilicate, and alkali metal salts of metasilicic acid such as lithium metasilicate, sodium metasilicate, and potassium metasilicate. Examples of alkyl silicate compounds include methyl silicate and ethyl silicate.

[0020] The silicon element content is 10 mass% or more with respect to the total solid content of the metal surface treatment agent of the present embodiment. It is preferable that the silicon element content is 20 mass% or more and 40 mass% or less. If the silicon element content is 10 mass% or more, the film formed by the metal surface treatment agent can be high-temperature fired, for example, at a temperature with a material reaching temperature (PMT) of 200°C or higher. If the silicon element content exceeds 40 mass%, the amount of other essential components is reduced, making it difficult to exhibit the stability or corrosion resistance of the metal surface treatment agent.

[0021] (Alkali metal salt(B))

[0022] The alkali metal salt (B) is an alkali metal salt other than a silicate compound, other than a vanadium compound, and other than a zirconium compound, and acts as a crosslinking agent. By including the alkali metal salt (B) in the metal surface treatment agent, the barrier properties of the film formed against water or corrosion factors (such as chloride ions) are improved, and consequently, the corrosion resistance imparted to the metal substrate can be improved. Specific examples of the alkali metal salt (B) include, for example, carbonates such as lithium carbonate, sodium carbonate, and potassium carbonate; bicarbonates such as lithium carbonate, sodium carbonate, sodium bicarbonate, and potassium bicarbonate; hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; and nitrites such as lithium nitrite, sodium nitrite, and potassium nitrite.

[0023] (Vanadium compound(C))

[0024] Vanadium compounds (C) are added to metal surface treatment agents and act as rust inhibitors (inhibitors). Vanadium compounds (C) are not particularly limited, but examples include vanadium pentoxide, metavanadic acid, ammonium metavanadate, sodium metavanadate, vanadium oxytrichloride, vanadyl sulfate, magnesium vanadate, vanadium trioxide, vanadium trichloride, vanadium dioxide, vanadyl acetylacetonate, vanadium acetylacetonate, etc.

[0025] In the present embodiment, the content of vanadium element in the total solid content of the metal surface treatment agent is preferably 0.1 to 10 mass%. More preferably, the content of vanadium element is 0.5 to 5 mass%. If the content of vanadium element is less than 0.1 mass%, sufficient corrosion resistance cannot be obtained. If the content of vanadium element exceeds 10 mass%, the stability and corrosion resistance of the metal surface treatment agent are reduced.

[0026] (Zirconium compound (D))

[0027] Zirconium compounds (D) act as crosslinking agents to improve the barrier properties of the formed film against water and corrosion agents (such as chloride ions), thereby improving corrosion resistance. Zirconium compounds (D) are not specifically limited, but examples include zirconium carbonate salts such as ammonium zirconium carbonate and potassium zirconium carbonate; alkali metal fluorozirconates such as K2ZrF6; zircon hydrofluoric acid (H2ZrF6); ammonium zircon fluoride ((NH4)2ZrF6); zirconium fluoride; zirconium nitrate; zirconium oxide; etc.

[0028] It is preferable that the content of zirconium element is 0.1 to 10 mass% with respect to the total solid content of the metal surface treatment agent of the present embodiment. When the content of zirconium element is within this range, the stability and corrosion resistance of the metal surface treatment agent are improved. It is more preferable that the content of zirconium element is 0.5 to 5 mass%. If the content of zirconium element is less than 0.1 mass%, a sufficient effect as a crosslinking agent cannot be obtained. If the content of zirconium element exceeds 10 mass%, the stability and corrosion resistance of the treatment agent are reduced.

[0029] In the present embodiment, the molar ratio (M / Si) of an alkali metal element (M) to a silicon element (Si) contained in the solid content of the metal surface treatment agent is preferably 0.5 to 1.2. The molar ratio (M / Si) is more preferably 0.6 to 1.1. If the molar ratio (M / Si) is less than 0.5, corrosion resistance is reduced. If the molar ratio (M / Si) exceeds 1.2, the stability of the metal surface treatment agent is reduced. In addition, the alkali metal element (M) includes an alkali metal element derived from a silicate compound (A), a vanadium compound (C), a zirconium compound (D), or other compounds other than an alkali metal salt (B).

[0030] (Chelating agent(E))

[0031] Chelating agent (E) is added to a metal surface treatment agent to stabilize zirconium in the metal surface treatment agent. Examples of chelating agents (E) include hydroxycarboxylic acids such as lactic acid, malic acid, tartaric acid, citric acid, and gluconic acid; ethylenediaminetetraacetic acid (EDTA); organophosphorus compounds such as 1-hydroxyethane-1,1-diphosphonic acid (HEDP); hydroxyamines such as triethanolamine (TEA); and salts of the above compounds.

[0032] The chelating agent (E) may include an organic phosphorus compound such as HEDP, but the metal surface treatment agent according to the present embodiment is preferably not to include phosphate compounds such as orthophosphoric acid (H3PO4), pyrophosphoric acid (H4P2O7), metaphosphoric acid (HPO3), and inorganic phosphorus compounds such as phosphates such as ammonium phosphate and sodium phosphate, from the perspective of reducing environmental impact caused by eutrophication.

[0033] (Other ingredients)

[0034] The metal surface treatment agent of the present embodiment includes water as a component other than the above. Additionally, the metal surface treatment agent may further include other components within a range that does not impede the above function. Examples of other components include resin components such as acrylic resin, urethane resin, epoxy resin, olefin resin, ethylene acrylic copolymer, polyester resin, polyolefin resin, alkyd resin, and polycarbonate resin. When the above resin component is included in the metal surface treatment agent, it is preferable that the solid content of the resin component relative to the total solid content of the metal surface treatment agent is 10 mass% or less, and more preferable that it is 5 mass% or less. Accordingly, high-temperature firing of the metal surface treatment agent can be performed preferably. Other components other than the above may include known components included in surface treatment agents, such as crosslinking agents, rust inhibitors, leveling agents, defoaming agents, and pH adjusters.

[0035] (Solid content)

[0036] The solid content of the metal surface treatment agent of the present embodiment is preferably 0.1 to 30 mass%, and more preferably 1.0 to 25 mass%.

[0037] Metal substrate

[0038] The metal substrate to be surface-treated by the metal surface treatment agent of the present embodiment is not particularly limited, but examples include cold-rolled steel, hot-rolled steel, stainless steel, electro-galvanized steel, hot-dip galvanized steel, zinc-aluminum alloy-based plated steel, zinc-iron alloy-based plated steel, zinc-aluminum-magnesium alloy-based plated steel, zinc-aluminum-magnesium alloy-based plated steel, aluminum-based plated steel, aluminum-silicon alloy-based plated steel, tin-based plated steel, lead-tin-based plated steel, chromium-based plated steel, Ni-based plated steel, etc. The shape of the metal substrate is not particularly limited, but examples include a plate shape.

[0039] Metal Surface Treatment Methods

[0040] The metal surface treatment agent of the present embodiment is a so-called coating-type metal surface treatment agent. The coating-type metal surface treatment agent is used by applying the surface treatment agent to the surface of a metal substrate and then firing (drying) the surface of the metal substrate without rinsing it with water. That is, the metal surface treatment method of the present embodiment comprises: a coating process of applying a metal surface treatment agent to the surface of a metal substrate; and a firing process of firing the applied metal surface treatment agent on the metal substrate. The coating-type metal surface treatment agent of the present embodiment has the advantage of making the formation of a metal surface treatment film relatively easy and not generating waste liquid.

[0041] The method of applying a metal surface treatment agent to the surface of a metal substrate during the coating process is not particularly limited, and examples include roll coating, bar coating, spray treatment, immersion treatment, etc. In addition, prior to the coating process, degreasing, pickling, etching, etc., may be performed on the surface of the metal substrate as necessary.

[0042] After the coating process in the firing process, the metal surface treatment agent applied to the metal substrate is fired. The firing method is not particularly limited. The firing temperature is not particularly limited, but it is preferable to set it to, for example, a material reaching temperature (PMT) of 200°C to 400°C. The firing time is not particularly limited, but it can be, for example, 3 to 180 seconds.

[0043] Metal surface treatment film

[0044] The film formed by the above-described metal surface treatment method (hereinafter sometimes simply referred to as "film") comprises each component of the metal surface treatment agent, excluding volatile components such as water. That is, the content of silicon element contained in the metal surface treatment film is 10 mass% or more. It is preferable that the molar ratio (M / Si) of alkali metal element (M) to silicon element (Si) contained in the metal surface treatment film is 0.5 to 1.2. It is preferable that the content of vanadium element contained in the metal surface treatment film is 0.1 to 10 mass%. It is preferable that the content of zirconium element contained in the metal surface treatment film is 0.1 to 10 mass%. The weight of the film is not particularly limited, but is 0.3 to 2.0 g / m² 2 It is preferable that it be 0.5 to 1.5 g / m² 2 It is more desirable that it is.

[0045] Surface-treated metal

[0046] The surface-treated metal according to the present embodiment is formed by forming the metal surface treatment film on the surface of the metal substrate. The surface-treated metal may have a coating film formed on the metal surface treatment film. The paint forming the coating film is not particularly limited, and a one-coat paint may be used, or a primer and a top coat may be used.

[0047] [Example]

[0048] The present invention will be described in more detail below based on examples, but the present invention is not limited to examples.

[0049] Manufacture of Metal Surface Treatment Agents

[0050] [Examples 1 to 36, Comparative Examples 1 to 4]

[0051] A silicic acid compound (A), an alkali metal salt (B), a vanadium compound (C), a zirconium compound (D), and a chelating agent (E) were weighed to achieve the solid content described in Tables 1 to 4 below, and an ion-exchanged water was added and mixed and stirred so that the total solid content concentration of these compositions in the metal surface treatment agent was 18 mass% to obtain a metal surface treatment agent. The unit of the mixing amount of each component described in Tables 1 to 4 represents parts by mass. The 'Si amount', 'V amount', and 'Zr amount' described in Tables 1 to 4 represent the content of silicon, vanadium, and zirconium elements (unit: mass%), respectively, relative to the total solid content of the metal surface treatment agent.

[0052] Detailed information regarding the types of raw materials listed in Tables 1 to 4 is as follows.

[0053] (Silicate compound(A))

[0054] A1: J Sodium Silicate No. 3 (Sodium Silicate, Japan Chemical Industry Co., Ltd.)

[0055] A2: Lithium Silicate 35 (Lithium Silicate, SiO2 / Li2O (molar ratio)=3.5, Japan Chemical Industry Co., Ltd.)

[0056] A3: Lithium Silicate 75 (Lithium Silicate, SiO2 / Li2O (molar ratio) = 7.5, Japan Chemical Industry Co., Ltd.)

[0057] A4: 2K Potassium Silicate (Potassium Silicate, Japan Chemical Industry Co., Ltd.)

[0058] A5: Hydrolysis product of ethyl silicate 28 (ethyl silicate, Corukort Co., Ltd.)

[0059] (Alkali metal salt(B))

[0060] B1: Sodium hydroxide

[0061] B2: Sodium bicarbonate

[0062] B3: Sodium carbonate

[0063] B4: Lithium hydroxide monohydrate

[0064] B5: Potassium hydroxide

[0065] B6: Sodium nitrite

[0066] B7: Lithium nitrite

[0067] (Vanadium compound(C))

[0068] C1 : Vanadyl sulfate

[0069] C2: Ammonium metavanadate

[0070] C3: Sodium metavanadate

[0071] (Zirconium compound (D))

[0072] D1: Zirconium ammonium carbonate

[0073] D2: Potassium zirconium carbonate

[0074] D3: AZ Coat 5800 MT (Ammonium Zirconium Carbonate 45% Solution, Sannokov Co., Ltd.)

[0075] D4: ZSL-10A (Zirconium oxide sol, pH 7.7, Jeil Rare Element Chemical Industry Co., Ltd.)

[0076] D5: Zirconium ammonium fluoride

[0077] D6: Zirconium Nitrate

[0078] (Chelating agent(E))

[0079] E1: Citric acid

[0080] E2: Gluconate

[0081] E3: 1-hydroxyethylidene-1,1-diphosphonic acid

[0082] E4: Triethanolamine

[0083] E5: Ethylenediaminetetraacetic acid

[0084] type Examples 1 2 3 4 5 6 7 8 9 10 Silicon compound (A) A1 89.8 - - - - - - - - - A2 - 89.8 87.3 78.7 87.0 47.8 51.9 87.0 85.1 78.7 A3 - - - - - - - - - - A4 - - - - - - - - - - A5 - - - - - - - - - - Alkali metal salt (B) B1 2.9 2.9 5.7 15.0 - - - - - - B2 - - - - 6.0 3.3 3.6 - - - B3 - - - - - - - 6.0 - - B4 - - - - - - - - 8.1 15.0 B5 - - - - - - - - - - B6 - - - - - - - - - - B7 - - - - - - - - - - Vanadium compound (C) C1 2.1 2.1 2.1 1.9 2.1 1.1 41.6 2.1 2.0 1.9 C2 - - - - - - - - - - C3 - - - - - - - - - - Zirconium compound (D) D1 - - - - - - - - - - D2 - - - - - - - - - - D3 3.1 3.1 3.0 2.7 3.0 38.2 1.8 3.0 2.9 2.7 D4 - - - - - - - - - - D5 - - - - - - - - - - D6 - - - - - - - - - - Chelating agent (E) E1 - - - - - - - - - - E2 - - - - - - - - - - E3 2.0 2.0 1.9 1.7 1.9 9.6 1.1 1.9 1.9 1.7 E4 - - - - - - - - - - E5 - - - - - - - - - - Total amount 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Si content (mass%) 31.6% 36.7% 35.7% 32.2% 35.6% 19.5% 21.2% 35.6% 34.8% 32.2% Amount of V (mass%) 0.7% 0.7% 0.6% 0.6% 0.6% 0.4% 13.0% 0.6% 0.6% 0.6% Zr amount (mass%) 1.0% 1.0% 1.0% 0.9% 1.0% 12.6% 0.6% 1.0% 1.0% 0.9% M / Si (molar ratio) 0.70 0.63 0.69 0.90 0.63 0.63 0.63 0.66 0.73 0.89

[0085] type Examples 11 12 13 14 15 16 17 18 19 20 Silicon compound (A) A1 - - - - - - - 89.8 - 89.8 A2 73.2 65.8 50.4 26.0 - - - - 78.7 - A3 - - - - 85.1 - - - - - A4 - - - - - 85.1 - - - - A5 - - - - - - 67.6 - - - Alkali metal salt (B) B1 - - - - - - - - - 2.9 B2 - - - - - - - - - - B3 - - - - - - - - - - B4 20.9 28.9 9.6 5.2 8.1 - - - - - B5 - - - - - 8.1 27.0 - - - B6 - - - - - - - 2.9 - - B7 - - - - - - - - 15.0 - Vanadium compound (C) C1 1.7 1.6 15.1 26.0 2.0 2.0 1.6 2.1 1.9 - C2 2.1 C3 - - - - - - - - - - Zirconium compound (D) D1 - - - - - - - - - - D2 - - - - - - - - - - D3 2.5 2.3 15.1 26.0 2.9 2.9 2.3 3.1 2.7 3.1 D4 - - - - - - - - - - D5 - - - - - - - - - - D6 - - - - - - - - - - Chelating agent (E) E1 - - - - - - - - - - E2 - - - - - - - - - - E3 1.6 1.5 9.7 16.7 1.9 1.9 1.5 2.0 1.7 2.0 E4 - - - - - - - - - - E5 - - - - - - - - - - Total amount 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Si content (mass%) 29.9% 26.9% 20.6% 10.6% 34.8% 27.6% 31.6% 31.6% 32.2% 31.6% Amount of V (mass%) 0.5% 0.5% 4.7% 8.1% 0.6% 0.6% 0.5% 0.7% 0.6% 0.9% Zr amount (mass%) 0.8% 0.7% 5.0% 8.6% 1.0% 1.0% 0.8% 1.0% 0.9% 1.0% M / Si (molar ratio) 1.04 1.29 0.89 0.90 0.41 1.11 0.57 0.67 0.57 0.70

[0086] type Examples 21 22 23 24 25 26 27 28 29 30 Silicon compound (A) A1 89.8 - - - - - 89.8 89.8 89.8 89.8 A2 - 79.1 80.2 78.7 79.9 79.9 - - - - A3 - - - - - - - - - - A4 - - - - - - - - - - A5 - - - - - - - - - - Alkali metal salt (B) B1 2.9 - - - - - 2.9 2.9 2.9 2.9 B2 - - - - - - - - - - B3 - - - - - - - - - - B4 - 15.1 15.3 15.0 15.2 15.2 - - - - B5 - - - - - - - - - - B6 - - - - - - - - - - B7 - - - - - - - - - - Vanadium compound (C) C1 - 1.9 1.9 1.9 1.9 1.9 2.1 2.1 2.1 2.1 C2 - - - - - - - - - - C3 2.1 - - - - - - - - - Zirconium compound (D) D1 - 1.2 - - - - - - - - D2 - - 1.2 - - - - - - - D3 3.1 - - - - - 3.1 3.1 3.1 3.1 D4 - - - 2.7 - - - - - - D5 - - - - 1.2 - - - - - D6 - - - - - 1.2 - - - - Chelating agent (E) E1 - - - - - - 2.0 - - - E2 - - - - - - - 2.0 - - E3 2.0 2.7 1.4 1.7 1.8 1.8 - - - - E4 - - - - - - - - 2.0 - E5 - - - - - - - - - 2.0 Total amount 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Si content (mass%) 31.6% 32.4% 32.8% 32.2% 32.7% 32.7% 31.6% 31.6% 31.6% 31.6% Amount of V (mass%) 0.9% 0.6% 0.6% 0.6% 0.6% 0.6% 0.7% 0.7% 0.7% 0.7% Zr amount (mass%) 1.0% 0.9% 0.3% 2.0% 0.5% 1.8% 1.0% 1.0% 1.0% 1.0% M / Si (molar ratio) 0.72 0.89 0.89 0.89 0.89 0.89 0.70 0.70 0.70 0.70

[0087] type Examples Comparative example 31 32 33 34 35 36 1 2 3 4 Silicon compound (A) A1 87.0 87.0 90.6 85.1 78.7 81.8 - - - - A2 - - - - - - 92.6 12.0 91.8 92.7 A3 - - - - - - - - - - A4 - - - - - - - - - - A5 - - - - - - - - - - Alkali metal salt (B) B1 - - - - - - - - 3.0 3.0 B2 6.0 - - - - - - - - - B3 - 6.0 - - - - - - - - B4 - - 2.2 8.1 15.0 15.6 - 4.8 - - B5 - - - - - - - - - - B6 - - - - - - - - - - B7 - - - - - - - - - - Vanadium compound (C) C1 2.1 2.1 2.2 2.0 1.9 1.9 2.2 24.0 - 2.2 C2 - - - - - - - - - - C3 - - - - - - - - - - Zirconium compound (D) D1 - - - - - 0.6 - - - - D2 - - - - - - - - - - D3 3.0 3.0 3.1 2.9 2.7 - 3.2 36.0 3.2 - D4 - - - - - - - - - - D5 - - - - - - - - - - D6 - - - - - - - - - - Chelating agent (E) E1 - - - - - - - - - - E2 - - - - - - - - - - E3 - - - - - - 2.0 23.1 2.0 2.0 E4 - - - - - - - - - - E5 1.9 1.9 2.0 1.9 1.7 - - - - - Total amount 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Si content (mass%) 30.6% 30.6% 31.9% 30.0% 27.7% 33.5% 37.9% 4.9% 37.5% 37.9% Amount of V (mass%) 0.6% 0.6% 0.7% 0.6% 0.6% 0.6% 0.7% 7.5% - 0.7% Zr amount (mass%) 1.0% 1.0% 1.0% 1.0% 0.9% 0.5% 1.0% 11.9% 1.0% - M / Si (molar ratio) 0.70 0.74 0.68 0.82 1.00 0.89 0.57 1.23 0.63 0.63

[0088] [Storage Stability Test] After leaving the metal surface treatment agents presented in Tables 1 to 4 in a 40℃ incubator for 7 days, the storage stability was visually evaluated according to the following criteria, and 2 was judged as passing. The results are shown in Tables 5 and 6.

[0089] 2: Contents of the metal surface treatment agent did not settle

[0090] 1: The contents of the metal surface treatment agent precipitate

[0091] <Production of Test Version>

[0092] Using the metal surface treatment agents shown in Tables 1 to 4, surface treatments were performed on cold-rolled steel sheets (SPCC270SD, Partec Co., Ltd.) specified in JIS G3135 as the metal substrate. The surface treatment proceeded according to the following procedure. First, the metal substrate was degreased by immersing it in a solution prepared at a concentration of 2% using Surf Cleaner 53NF from Japan Paint Surf Chemical Co., Ltd. at 45°C for 2 minutes. After degreasing, the metal substrate was washed with water and dried. Subsequently, the metal surface treatment agents shown in Tables 1 to 4 were applied to the surface of the metal substrate using a bar coater to achieve a film thickness of 0.7 g / m² 2The coating was applied to achieve the desired result. Subsequently, the metal substrate after the coating was heated in an oven at a temperature of 550°C for 15 seconds to sinter. The material temperature reached during sintering (PMT) was 300°C. The following evaluations were performed using test plates for each example and comparative example obtained above.

[0093] <Evaluation>

[0094] [Corrosion Resistance (Salt Spray Test (SST))]

[0095] Each test plate was placed in a salt spray corrosion tester specified in JIS Z2317 for 4, 8, and 16 hours, and the area of ​​red rust was visually evaluated according to the following criteria; a result of 2 or more was considered a pass. The results are shown in Tables 5 and 6.

[0096] 4: Area of ​​red rust after 16 hours of SST is 5% or less of the test plate area

[0097] 3: Area of ​​red rust after 8 hours of SST is 5% or less of the test plate area

[0098] 2: Area of ​​red rust after 4 hours of SST is 5% or less of the test plate area

[0099] 1: Area of ​​red rust formation exceeds 5% of the test plate area after 4 hours of SST

[0100] Examples 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Corrosion resistance 3 3 4 4 4 2 2 4 4 4 4 2 3 2 2 3 3 3 3 3 Storage stability 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

[0101] Examples Comparative example 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 1 2 3 4 Corrosion resistance 3 4 3 3 3 3 4 4 3 4 4 4 3 4 4 3 1 1 1 2 Storage safety 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 1 2 1

[0102] From the results of Tables 5 and 6, the following results can be confirmed. The test plates according to the example each have superior corrosion resistance results compared to the test plates according to Comparative Examples 1, 3, and 4, which do not contain specific components, and the test plate according to Comparative Example 2, which has a silicon element content of less than 10 mass%. In addition, the metal surface treatment agent according to the example has superior storage stability compared to the surface treatment agents according to Comparative Examples 2 and 4.

Claims

Claim 1 A metal surface treatment agent comprising: a silicate compound (A); an alkali metal salt (B) other than a silicate compound, other than a vanadium compound, and other than a zirconium compound; a vanadium compound (C); a zirconium compound (D); and water; wherein, with respect to the total solid content of the metal surface treatment agent, the content of silicon element is 20 mass% or more and 40 mass% or less, and the solid content with respect to the total solid content of the resin component metal surface treatment agent is 10 mass% or less. Claim 2 In claim 1, the above silicate compound (A) is a metal surface treatment agent that is a silicate of an alkali metal. Claim 3 A metal surface treatment agent according to claim 1 or 2, wherein the molar ratio (M / Si) of an alkali metal element (M) to a silicon element (Si) contained in the solid portion of the metal surface treatment agent is 0.5 to 1.

2. Claim 4 A metal surface treatment agent according to claim 1 or 2, wherein the content of vanadium element is 0.1 to 10 mass% and the content of zirconium element is 0.1 to 10 mass% with respect to the total solid content of the metal surface treatment agent. Claim 5 A metal surface treatment agent comprising a chelating agent (E) further comprising, in claim 1 or 2. Claim 6 A metal surface treatment film cured by the metal surface treatment agent of claim 1 or 2. Claim 7 Surface-treated metal having a metal surface treatment film as described in Clause 6.

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