Metal surface treatment agent

Abstract

Provided is a metal surface treatment agent which can be sintered at high temperatures and is capable of imparting high corrosion resistance to a metal substrate. A metal surface treatment agent which contains (A) a silicic acid compound, (B) an alkali metal salt other than a silicic acid compound, a vanadium compound and a zirconium compound, (C) a vanadium compound, (D) a zirconium compound and water, and wherein the content of silicon element is 10 mass% or more relative to the total solid content of the metal surface treatment agent. The silicic acid compound (A) is preferably a silicate of an alkali metal.

Description

Technical Field

[0001] The present invention relates to a metal surface treating agent. Background Art

[0002] In the past, zinc phosphate treatment and zirconium-based chemical treatment were known as technologies for imparting corrosion resistance to metal substrates such as steel. Zinc phosphate treatment is used as a chemical treatment for coating bases, but since phosphorus, a eutrophic element, and nickel, which may be carcinogenic, are used as film components, there has been a tendency to avoid its use in recent years from the perspectives of environmental protection and the impact on the human body.

[0003] Zirconium-based chemical treatment is a technology that has been used in the past for aluminum-based materials. As for the technology for imparting high corrosion resistance to steel materials, the current situation is that there is still room for improvement.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-186456 Summary of the invention

[0007] Problems to be solved by the invention

[0008] The technology described in Patent Document 1 is related to a surface-treated steel plate, wherein the surface-treated film contains an acrylic resin emulsion. When the main component of the surface-treated film contains a resin component such as an acrylic resin emulsion, it is currently difficult to make the raw material reaching temperature (PMT) during sintering a high temperature such as more than 200° C., and sufficient heat resistance and durability of the coating film cannot be obtained, and sufficient corrosion resistance after coating cannot be obtained.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a metal surface treatment agent that can be sintered at a high temperature and can impart high corrosion resistance to a metal substrate.

[0010] Methods for solving problems

[0011] (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, the vanadium compound and the zirconium compound, a vanadium compound (C), a zirconium compound (D) and water, wherein the content of silicon element is 10% by mass or more relative to the total solid content of the metal surface treatment agent.

[0012] (2) The metal surface treatment agent according to (1), wherein the silicic acid compound (A) is an alkali metal silicate.

[0013] (3) The metal surface treatment agent according to (1) or (2), wherein a molar ratio (M / Si) of the alkali metal element (M) to the silicon element (Si) contained in the solid content of the metal surface treatment agent is 0.5 to 1.2.

[0014] (4) The metal surface treatment agent according to 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 % based on the total solid content of the metal surface treatment agent.

[0015] (5) The metal surface treatment agent according to any one of (1) to (4), further comprising a chelating agent (E).

[0016] (6) A metal surface treatment film obtained by curing the metal surface treatment agent according to any one of (1) to (5).

[0017] (7) A surface-treated metal having the metal surface-treated film described in (6).

[0018] Effects of the Invention

[0019] According to the present invention, a metal surface treatment agent that can be sintered at a high temperature and can impart high corrosion resistance to a metal substrate can be provided. DETAILED DESCRIPTION

[0020] Hereinafter, a metal surface treatment agent according to an embodiment of the present invention will be described. However, the present invention is not limited to the description of the following embodiment.

[0021] <Metal surface treatment agent>

[0022] The metal surface treatment agent of this embodiment contains a silicic acid compound (A), an alkali metal salt (B) other than a silicic acid compound, a vanadium compound, and a zirconium compound, a vanadium compound (C), a zirconium compound (D), and water. In addition, it is preferred to contain a chelating agent (E).

[0023] (Silicic acid compound (A))

[0024] The silicic acid compound (A) is the main component of the film formed by the metal surface treatment agent. By making the main component of the film a silicic acid compound (A) as an inorganic compound, high-temperature sintering of the film can be performed. As specific examples of the silicic acid compound (A), alkali metal silicates, colloidal silica, alkyl silicate compounds, hydrolyzates of alkyl silicate compounds, polycondensation products of alkyl silicate compounds, etc. can be cited. From the viewpoint of corrosion resistance, the silicic acid compound (A) is preferably an alkali metal silicate. As alkali metal silicates, for example, alkali metal salts of orthosilicic acid such as lithium orthosilicate, sodium orthosilicate, potassium orthosilicate, alkali metal salts of metasilicic acid such as lithium metasilicate, sodium metasilicate, potassium metasilicate, etc. can be cited. As alkyl silicate compounds, methyl silicate, ethyl silicate, etc. can be cited.

[0025] The content of silicon is 10% by mass or more relative to the total solid content of the metal surface treatment agent of the present embodiment. The content of the silicon is preferably 20% by mass or more and 40% by mass or less. By making the content of the silicon more than 10% by mass, for example, the raw material reaching temperature (PMT) can be set to a temperature of more than 200° C. to perform high temperature sintering on the film formed by the metal surface treatment agent. If the content of the silicon exceeds 40% by mass, the amount of other essential components becomes less, and it is difficult to exert the stability and corrosion resistance of the metal surface treatment agent.

[0026] (Alkali Metal Salt (B))

[0027] The alkali metal salt (B) is an alkali metal salt other than a silicate compound, a vanadium compound, and a zirconium compound, and acts as a crosslinking agent. By including an alkali metal salt (B) in the metal surface treatment agent, the barrier property of the formed film to water and corrosion factors (chloride ions, etc.) is improved, and as a result, the corrosion resistance imparted to the metal substrate can be improved. Specific examples of the alkali metal salt (B) are not particularly limited, and examples thereof include carbonates such as lithium carbonate, sodium carbonate, and potassium carbonate, bicarbonates such as lithium bicarbonate, 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.

[0028] (Vanadium compound (C))

[0029] The vanadium compound (C) acts as a rust inhibitor (inhibitor) by being added to a metal surface treatment agent. The vanadium compound (C) is not particularly limited, and examples thereof include vanadium pentoxide, metavanadic acid, ammonium metavanadate, sodium metavanadate, vanadium oxytrichloride, vanadium oxysulfate, magnesium vanadate, vanadium trioxide, vanadium trichloride, vanadium dioxide, vanadium oxyacetylacetonate, vanadium acetylacetonate, and the like.

[0030] The content of vanadium is preferably 0.1 to 10% by mass relative to the total solid content of the metal surface treatment agent of the present embodiment. The content of the vanadium is more preferably 0.5 to 5% by mass. When the content of the vanadium is less than 0.1% by mass, sufficient rust resistance cannot be obtained. When the content of the vanadium exceeds 10% by mass, the stability and corrosion resistance of the metal surface treatment agent are reduced.

[0031] (Zirconium compound (D))

[0032] The zirconium compound (D) acts as a crosslinking agent, thereby improving the barrier properties of the formed film against water and corrosive factors (chloride ions, etc.), thereby improving corrosion resistance. The zirconium compound (D) is not particularly limited, and examples thereof include zirconium carbonate salts such as ammonium zirconium carbonate and potassium zirconium carbonate, alkali metal fluorozirconates such as K2ZrF6, hexafluorozirconic acid (H2ZrF6), ammonium zirconium fluoride ((NH4)2ZrF6), zirconium fluoride, zirconium nitrate, zirconium oxide, etc.

[0033] The content of zirconium is preferably 0.1 to 10% by mass relative to the total solid content of the metal surface treatment agent of the present embodiment. When the content of zirconium is within this range, the stability and corrosion resistance of the metal surface treatment agent are improved. The content of the zirconium is more preferably 0.5 to 5% by mass. When the content of the zirconium is less than 0.1% by mass, the effect as a crosslinking agent cannot be obtained. When the content of the zirconium exceeds 10% by mass, the stability and corrosion resistance of the treatment agent are reduced.

[0034] The molar ratio (M / Si) of the alkali metal element (M) contained in the solid component of the metal surface treatment agent of the present embodiment to the silicon element (Si) is preferably 0.5 to 1.2. The above-mentioned molar ratio (M / Si) is more preferably 0.6 to 1.1. When the above-mentioned molar ratio (M / Si) is lower than 0.5, the corrosion resistance is reduced. When the above-mentioned molar ratio (M / Si) exceeds 1.2, the stability of the metal surface treatment agent is reduced. It should be noted that the above-mentioned alkali metal element (M) includes alkali metal elements from silicate compounds (A), vanadium compounds (C), zirconium compounds (D) or other compounds other than alkali metal salts (B).

[0035] (Chelating agent (E))

[0036] The chelating agent (E) is added to the metal surface treatment agent to stabilize the zirconium in the metal surface treatment agent. The chelating agent (E) is not particularly limited, and examples thereof include hydroxycarboxylic acids such as lactic acid, malic acid, tartaric acid, citric acid, and gluconic acid, organic phosphorus compounds such as ethylenediaminetetraacetic acid (EDTA) and 1-hydroxyethane-1,1-diphosphonic acid (HEDP), hydroxylamines such as triethanolamine (TEA), and salts of the above compounds.

[0037] As a chelating agent (E), an organic phosphorus compound such as the above-mentioned HEDP may be included, but from the viewpoint of reducing the environmental impact caused by eutrophication, the metal surface treatment agent of this embodiment preferably does not include inorganic phosphorus compounds such as phosphoric acids such as orthophosphoric acid (H3PO4), pyrophosphoric acid (H4P2O7), and metaphosphoric acid (HPO3), and phosphates such as ammonium phosphate and sodium phosphate.

[0038] (Other ingredients)

[0039] The metal surface treatment agent of the present embodiment includes water as a component other than the above. In addition, in the metal surface treatment agent, other components may be further included within the range that does not hinder the above functions. As other components, for example, resin components such as olefin resins such as acrylic resins, polyurethane resins, epoxy resins, and ethylene acrylic acid copolymers, polyester resins, polyolefin resins, alkyd resins, and polycarbonate resins may be cited. In the case where the above-mentioned resin component is included in the metal surface treatment agent, the solid content of the resin component relative to the total solid content of the metal surface treatment agent is preferably 10% by mass or less, more preferably 5% by mass or less. Thus, high-temperature sintering of the metal surface treatment agent can be preferably performed. As other components other than the above, known components contained in surface treatment agents such as crosslinking agents, rust inhibitors, leveling agents, defoamers, and pH adjusters may be cited.

[0040] (Solid content)

[0041] The solid content of the metal surface treatment agent of the present embodiment is preferably 0.1 to 30% by mass, more preferably 1.0 to 25% by mass.

[0042] <Metal substrate>

[0043] The metal substrate to be surface treated by the metal surface treatment agent of the present embodiment is not particularly limited, and examples thereof include cold-rolled steel, hot-rolled steel, stainless steel, electrogalvanized steel, hot-dip galvanized steel, zinc-aluminum alloy plated steel, zinc-iron alloy plated steel, zinc-magnesium alloy plated steel, zinc-aluminum-magnesium alloy plated steel, aluminum plated steel, aluminum-silicon alloy plated steel, tin plated steel, lead-tin plated steel, chromium plated steel, Ni plated steel, etc. The shape of the metal substrate is not particularly limited, and examples thereof include a plate shape, etc.

[0044] <Metal surface treatment method>

[0045] 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 can be used in a method in which the surface treatment agent is applied to the surface of a metal substrate and the surface of the metal substrate is sintered (dried) without washing. That is, the metal surface treatment method in the present embodiment has a coating step of coating the metal surface treatment agent on the surface of the metal substrate and a sintering step of sintering the metal substrate coated with the metal surface treatment agent. The coating type metal surface treatment agent of the present embodiment has the advantage of being able to form a metal surface treatment film more easily and without generating waste liquid.

[0046] In the coating process, the method for coating the metal surface treatment agent on the surface of the metal substrate is not particularly limited, and examples thereof include methods utilizing a roll coating method, a rod coating method, a spray treatment method, an immersion treatment method, etc. It should be noted that before the coating process, the surface of the metal substrate may be subjected to a degreasing treatment, a pickling treatment, or an etching treatment as required.

[0047] In the sintering process, after the coating process, the metal surface treatment agent coated on the metal substrate is sintered. There is no particular limitation on the sintering method. There is no particular limitation on the sintering temperature, and for example, it is preferably set to 200°C to 400°C based on the raw material reaching temperature (PMT). There is no particular limitation on the sintering time, and for example, it can be set to 3 to 180 seconds.

[0048] <Metal surface treatment film>

[0049] The film formed by the above-mentioned metal surface treatment method (hereinafter, sometimes simply recorded as "film") contains all the components of the above-mentioned metal surface treatment agent except volatile components such as water. That is, the content of silicon element contained in the metal surface treatment film is 10% by mass or more. Preferably, the molar ratio (M / Si) of the alkali metal element (M) contained in the metal surface treatment film to the silicon element (Si) is 0.5 to 1.2. The content of vanadium element contained in the metal surface treatment film is preferably 0.1 to 10% by mass. The content of zirconium element contained in the metal surface treatment film is preferably 0.1 to 10% by mass. As for the film weight, it is not particularly limited, and is preferably 0.3 to 2.0 g / m 2 , more preferably 0.5 to 1.5 g / m 2 .

[0050] <Surface treated metal>

[0051] The surface treated metal of this embodiment is formed by forming the above-mentioned metal surface treated film on the surface of the above-mentioned metal substrate. The surface treated metal can be a metal having a coating film formed on the above-mentioned metal surface treated film. There is no particular limitation on the coating material for forming the coating film, and a single coating material can be used, or a primer and a top coating can be used.

[0052] Example

[0053] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the Examples.

[0054] <Preparation of Metal Surface Treatment Agent>

[0055] [Example 1 to Example 36, Comparative Example 1 to Comparative Example 4]

[0056] The silicate compound (A), alkali metal salt (B), vanadium compound (C), zirconium compound (D), and chelating agent (E) are weighed so as to obtain the solid content described in the following Tables 1 to 4, and ion exchange water is added and mixed and stirred so as to obtain a metal surface treatment agent in such a manner that the total solid content concentration of these compositions in the metal surface treatment agent becomes 18% by mass. The unit of the 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 respectively represent the content of silicon element, vanadium element, and zirconium element relative to the total solid content of the metal surface treatment agent (unit: mass %).

[0057] The details of the types of raw materials described in Tables 1 to 4 are as follows.

[0058] (Silicic acid compound (A))

[0059] A1: J Sodium Silicate No. 3 (sodium silicate, manufactured by Nippon Chemical Industry Co., Ltd.)

[0060] A2: Lithium silicate 35 (lithium silicate, SiO2 / Li2O (molar ratio) = 3.5, manufactured by Nippon Chemical Industry Co., Ltd.)

[0061] A3: Lithium silicate 75 (lithium silicate, SiO2 / Li2O (molar ratio) = 7.5, manufactured by Nippon Chemical Industry Co., Ltd.)

[0062] A4: 2K potassium silicate (potassium silicate, manufactured by Nippon Chemical Industry Co., Ltd.)

[0063] A5: Hydrolysis product of ethyl silicate 28 (ethyl silicate, manufactured by Colcoat Co., Ltd.)

[0064] (Alkali Metal Salt (B))

[0065] B1: Sodium hydroxide

[0066] B2: Sodium bicarbonate

[0067] B3: Sodium carbonate

[0068] B4: Lithium hydroxide monohydrate

[0069] B5: Potassium hydroxide

[0070] B6: Sodium Nitrite

[0071] B7: Lithium Nitrite

[0072] (Vanadium compound (C))

[0073] C1: Vanadyl Sulfate

[0074] C2: Ammonium metavanadate

[0075] C3: Sodium metavanadate

[0076] (Zirconium compound (D))

[0077] D1: Ammonium zirconium carbonate

[0078] D2: Potassium zirconium carbonate

[0079] D3: AZ Coat 5800MT (45% ammonium zirconium carbonate solution, manufactured by Sannopco Co., Ltd.)

[0080] D4: ZSL-10A (zirconia sol, pH 7.7, manufactured by Daiichi Kizenso Chemical Industry Co., Ltd.)

[0081] D5: Ammonium zirconium fluoride

[0082] D6: Zirconium Nitrate

[0083] (Chelating agent (E))

[0084] E1: Citric acid

[0085] E2: Gluconate

[0086] E3: 1-Hydroxyethylidene-1,1-diphosphonic acid

[0087] E4: Triethanolamine

[0088] E5: Ethylenediaminetetraacetic acid

[0089] [Table 1]

[0090]

[0091] [Table 2]

[0092]

[0093] [Table 3]

[0094]

[0095] [Table 4]

[0096]

[0097] [Storage stability test]

[0098] The metal surface treatment agents shown in Tables 1 to 4 were left to stand in a thermostatic chamber at 40° C. for 7 days, and then visually evaluated for storage stability according to the following criteria, with 2 being considered acceptable. The results are shown in Tables 5 and 6.

[0099] 2: The contents of the metal surface treatment agent have not settled

[0100] 1: Settling of the contents of the metal surface treatment agent

[0101] <Preparation of test plate>

[0102] The cold-rolled steel sheets (SPCC270SD, manufactured by PALTEK Co., Ltd.) specified in JIS G3135, which serve as metal substrates, were surface treated using the metal surface treatment agents shown in Tables 1 to 4. The surface treatment was performed according to the following steps. First, the metal substrate was degreased by immersing it in a solution obtained by adjusting Surf cleaner 53NF manufactured by Nippon Paint Surf Chemicals Co., Ltd. to a concentration of 2% at 45°C for 2 minutes. The degreased metal substrate was washed with water and then dried. Next, the metal surface treatment agents shown in Tables 1 to 4 were applied using a rod coater to a film amount of 0.7 g / m 2 The coated metal substrate was then sintered in an oven at 550°C for 15 seconds. The raw material reaching temperature (PMT) during sintering was 300°C. The following evaluations were performed using the test plates of the embodiments and comparative examples obtained above.

[0103] <Evaluation>

[0104] [Corrosion resistance (Salt spray test (SST))]

[0105] Each test plate was placed in a salt spray corrosion tester specified in JIS Z2317 for 4 hours, 8 hours, and 16 hours, and the red rust generation area was visually evaluated according to the following criteria, and an area of ​​2 or more was considered acceptable. The results are shown in Tables 5 and 6.

[0106] 4: After 16 hours of SST, the area of ​​red rust is less than 5% of the area of ​​the test plate

[0107] 3: The area of ​​red rust after 8 hours of SST is less than 5% of the area of ​​the test plate

[0108] 2: The area of ​​red rust after 4 hours of SST is less than 5% of the area of ​​the test plate

[0109] 1: After 4 hours of SST, the area of ​​red rust exceeds 5% of the area of ​​the test plate

[0110] [Table 5]

[0111]

[0112] [Table 6]

[0113]

[0114] The following results can be seen from the results of Tables 5 and 6. The test plates of the examples were superior in corrosion resistance to the test plates of Comparative Examples 1, 3, and 4, which did not contain any specific component, and the test plate of Comparative Example 2, which had a silicon content of less than 10% by mass. In addition, the metal surface treatment agent of the example was superior in storage stability to the surface treatment agents of Comparative Examples 2 and 4.

Claims

1. A metal surface treatment agent comprising a silicate compound (A), an alkali metal salt (B) other than a silicate compound, a vanadium compound and a zirconium compound, a vanadium compound (C), a zirconium compound (D) and water, The content of silicon element is 10 mass % or more based on the total solid content of the metal surface treatment agent.

2. The metal surface treatment agent according to claim 1, wherein The silicic acid compound (A) is an alkali metal silicate.

3. The metal surface treatment agent according to claim 1 or 2, wherein The molar ratio of the alkali metal element M to the silicon element Si contained in the solid content of the metal surface treatment agent, that is, M / Si, is 0.5 to 1.

2.

4. The metal surface treatment agent according to claim 1 or 2, wherein The content of the vanadium element is 0.1 to 10% by mass and the content of the zirconium element is 0.1 to 10% by mass based on the total solid content of the metal surface treatment agent. The metal surface treatment agent according to claim 1 or 2, further comprising a chelating agent (E).

6. A metal surface treatment film formed by curing the metal surface treatment agent according to claim 1 or 2.

7. A surface-treated metal having the metal surface-treated film according to claim 6.

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