Method for manufacturing surface-treated metal member

Abstract

To provide a method for manufacturing a surface-treated metal member in which preferable corrosion resistance of a surface-treated metal member is obtained, and poor external appearance can be suppressed.SOLUTION: A method for manufacturing a surface-treated metal member includes a degreasing / washing step, a surface-treating agent contacting step, and a drying step, where an aqueous surface treating agent contains silicon-containing compound (A) which does not contain polar functional group other than silanol group, water-soluble amino group-containing compound (B) and water, mass concentration of (A+B) which is the total mass concentration of the silicon-containing compound (A) and the water-soluble amino group-containing compound (B) in the aqueous surface treating agent is within the range of 1 to 30 g / L, and a value of a mass concentration ratio {A / (A+B)} of the silicon-containing compound (A) to the total mass concentration (A+B) of the silicon-containing compound (A) and the water-soluble amino group-containing compound (B) in the aqueous surface treating agent is within the range of 45 to 95%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a surface-treated metal member.

Background Art

[0002] Conventionally, when painting the surface of a metal member, a chemical conversion treatment is usually performed to form a chemical conversion film on the surface of the metal member before painting, for the purpose of imparting corrosion resistance, coating film adhesion, etc. to the metal member.

[0003] As the chemical conversion treatment, a chemical conversion treatment using a phosphate-based surface treatment agent or a zirconium-based surface treatment agent containing no harmful heavy metals such as nickel has been conventionally performed. However, conventional surface treatment agents have problems such as being unable to use the surface treatment agent at room temperature, generating chemical conversion sludge as a by-product, and increasing the treatment time and cost due to the need for one or more water washing steps after the chemical conversion treatment. Therefore, in recent years, a coating-type surface treatment agent capable of solving the above problems has been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the time interval from when a coating-type surface treatment agent as disclosed in Patent Document 1 is brought into contact with a metal member until it is dried becomes long, there is a possibility that liquid dripping of the surface treatment agent or liquid accumulation occurs in the processed parts of the metal member. If liquid dripping of the surface treatment agent occurs, there is a risk that the corrosion resistance of the metal member will be partially reduced. If liquid accumulation of the surface treatment agent occurs, there is a risk that the appearance of the metal member will be defective.

[0006] The present invention has been made in view of the above, and an object thereof is to provide a method for manufacturing a surface-treated metal member that can obtain preferable corrosion resistance of the surface-treated metal member and suppress appearance defects.

Means for Solving the Problems

[0007] (1) The present disclosure is a method for manufacturing a surface-treated metal member, including a degreasing and water-washing step of degreasing a metal member and then washing it with water to form a degreased and water-washed metal member, a surface treatment agent contact step of bringing the degreased and water-washed metal member into contact with an aqueous surface treatment agent to form a metal member having a liquid film on the surface, and a drying step of drying the liquid film of the metal member having a liquid film on the surface to form a film. The aqueous surface treatment agent contains a silicon-containing compound (A) that does not contain a polar functional group other than a silanol group, a water-soluble amino group-containing compound (B), and water. In the aqueous surface treatment agent, the mass concentration of (A + B), which is the total mass concentration of the silicon-containing compound (A) and the water-soluble amino group-containing compound (B), is in the range of 1 to 30 g / L, and the value of the mass concentration ratio {A / (A + B)} of the silicon-containing compound (A) to the total mass concentration (A + B) of the silicon-containing compound (A) and the water-soluble amino group-containing compound (B) in the aqueous surface treatment agent is in the range of 45 to 95%. The present disclosure relates to a method for manufacturing a surface-treated metal member.

[0008] (2) The method for manufacturing a surface-treated metal member according to (1), wherein the metal member is a processed and formed member.

[0009] (3) The method for manufacturing a surface-treated metal member according to (1) or (2), wherein the silicon-containing compound (A) is a silicon-containing compound having two or more silanol groups in one molecule.

[0010] (4) The method for manufacturing a surface-treated metal member according to any one of (1) to (3), wherein the silicon-containing compound (A) is 1,2-bis(triethoxysilyl)ethane.

[0011] (5) The water-soluble amino group-containing compound (B) is an aminosilane or an amine-modified epoxy resin, and the method for manufacturing a surface-treated metal member according to any one of (1) to (4).

[0012] (6) The time interval from the end of the surface treatment agent contact step to the start of the drying step is 30 seconds or more, and the method for manufacturing a surface-treated metal member according to any one of (1) to (5).

[0013] (7) The amount of the film after drying of the film formed by the aqueous surface treatment agent is in the range of 1 to 100 mg / m 2 and the method for manufacturing a surface-treated metal member according to any one of (1) to (6). [Advantages of the Invention]

[0014] According to the present invention, it is possible to provide a method for manufacturing a surface-treated metal member that can obtain preferable corrosion resistance of the surface-treated metal member and suppress appearance defects. [Embodiments for Carrying Out the Invention]

[0015] Hereinafter, a method for manufacturing a surface-treated metal member according to an embodiment of the present invention will be described. The present invention is not limited to the description of the following embodiments.

[0016] [Method for Manufacturing a Surface-Treated Metal Member] The method for manufacturing a surface-treated metal member according to the present embodiment includes a degreasing and water washing step, a surface treatment agent contact step, and a drying step. Since the method for manufacturing a surface-treated metal member according to the present embodiment has a surface treatment agent contact step using a coating-type aqueous surface treatment agent, unlike a zinc phosphate treatment or the like, a water washing step after the surface treatment agent contact step can be omitted. Therefore, the treatment time and treatment cost can be reduced. A topcoat film may be further formed on the surface of the surface-treated metal member obtained by the above manufacturing method with a topcoat paint. The surface-treated metal member according to the present embodiment can obtain preferable adhesion with the above topcoat film. The topcoat paint is not particularly limited and may be a powder paint, an aqueous paint, or a solvent-based paint.

[0017] <Metal member> The metal member to be surface-treated by the method for manufacturing a surface-treated metal member according to the present embodiment is not particularly limited, and known metal members can be mentioned. Examples of the metal member include an iron-based substrate, an aluminum-based substrate, a zinc-based substrate, a magnesium-based substrate, etc. The iron-based substrate means a substrate containing at least any one of iron and iron alloys. Specific examples of the iron-based substrate include cold-rolled steel sheets, hot-rolled steel sheets, stainless steels, electro-galvanized steel sheets, hot-dip galvanized steel sheets, zinc-aluminum alloy-based plated steel sheets, zinc-iron alloy-based plated steel sheets, zinc-magnesium alloy-based plated steel sheets, zinc-aluminum-magnesium alloy-based plated steel sheets, aluminum-based plated steel sheets, aluminum-silicon alloy-based plated steel sheets, tin-based plated steel sheets, lead-tin-based plated steel sheets, chromium-based plated steel sheets, Ni-based plated steel sheets, and other metal steel sheets. The aluminum-based substrate means a substrate containing at least any one of aluminum and aluminum alloys. The zinc-based substrate means a substrate containing at least any one of zinc and zinc alloys. The magnesium-based substrate means a substrate containing at least any one of magnesium and magnesium alloys.

[0018] In the present embodiment, the metal member may be a processed and formed member. According to the method for manufacturing a surface-treated metal member according to the present embodiment, even if the metal member to be processed is a processed and formed member, favorable corrosion resistance of the manufactured surface-treated metal member can be obtained, and appearance defects can be suppressed. The processed and formed member means, for example, a metal member that has been processed such as by laser processing or press processing.

[0019] (Degreasing and water washing process) The degreasing and water washing process is a process of degreasing a metal member and then washing it with water to form a degreased and water-washed metal member. By degreasing the metal member, the oil and / or dirt adhering to the surface of the metal member are removed. The method of degreasing the metal member is not particularly limited. For example, a method of performing an immersion treatment at 30 to 55 °C for about several minutes with a degreasing agent such as a phosphorus-free and nitrogen-free degreasing and cleaning solution can be mentioned. Before the above degreasing method, a preliminary degreasing treatment may be performed. By washing the degreased metal member with water, the degreasing agent on the surface of the degreased metal member is removed. The method of washing with water is not particularly limited. For example, a method of performing a spray treatment one or more times with a large amount of washing water can be mentioned.

[0020] (Surface treatment agent contact process) The surface treatment agent contact process is a process of promptly bringing the degreased and water-washed metal member obtained by the above degreasing and water washing process into contact with an aqueous surface treatment agent to form a metal member having a liquid film on the surface. The time interval from the end of the dehydration and water washing process to the start of the surface treatment agent contact process is preferably 30 seconds or less. The method of bringing the degreased and water-washed metal member into contact with the aqueous surface treatment agent is not particularly limited. For example, an immersion method, a spray method, a roll coating method, a bar coating method, etc. can be mentioned. Alternatively, the aqueous surface treatment agent may be poured over the degreased and water-washed metal member to bring them into contact. The conditions for bringing the degreased and water-washed metal member into contact with the aqueous surface treatment agent are not particularly limited in terms of temperature and time. The temperature of the aqueous surface treatment agent during contact can be, for example, 10 to 40 °C. The time during contact can be arbitrarily set according to the conditions of the equipment and members to be applied, and can be, for example, 10 to 30 seconds. In the surface treatment agent contact process, when the aqueous surface treatment agent can freeze in a cold environment, a minimum amount of heating may be performed to prevent the aqueous surface treatment agent from freezing, but in a normal environment, it is not necessary to heat the aqueous surface treatment agent. In the surface treatment agent contact process, the number of times of bringing the degreased and water-washed metal member into contact with the aqueous surface treatment agent can be, for example, once.

[0021] <Aqueous surface treatment agent> The aqueous surface treatment agent used in the above surface treatment agent contact step contains a silicon-containing compound (A) that does not contain polar functional groups other than silanol groups (hereinafter, may be simply referred to as "silicon-containing compound (A)"), a water-soluble amino group-containing compound (B), and water. By containing the silicon-containing compound (A) in the aqueous surface treatment agent, the silicon-containing compound (A) is adsorbed and film-formed on the metal base material. Further, the silicon-containing compound (A) functions as a main binder of the film formed by the aqueous surface treatment agent. By containing the water-soluble amino group-containing compound (B) in the aqueous surface treatment agent, the adhesion between the film formed by the aqueous surface treatment agent and the topcoat film is improved.

[0022] The silicon-containing compound (A) is a compound that does not contain polar functional groups other than silanol groups. In other words, it is a compound that may contain non-polar functional groups in addition to silanol groups. Examples of the non-polar functional group include hydrocarbon groups. In this specification and the claims, the concept of silanol groups includes silyl groups that can generate silanol groups by hydrolysis in addition to silanol groups. The silicon-containing compound (A) preferably has two silanol groups in one molecule. Examples of such a silicon-containing compound (A) include compounds represented by the following formula (I).

[0023]

Chemical formula

[0024] In the above formula (I), R 1 , R 2 , R 3 , and R 4 each independently represents a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms. Examples of the monovalent organic group include hydrocarbon groups such as alkyl groups, alkenyl groups, cycloalkyl groups, and aryl groups. As the monovalent organic group, alkyl groups having 1 to 4 carbon atoms such as methyl groups and ethyl groups are preferred.

[0025] In the above formula (I), Y represents a divalent organic group. Examples of the divalent organic group include an alkylene group or a group containing the above divalent organic group as a partial structure. The number of carbon atoms in the above divalent organic group is preferably 2 to 30, more preferably 2 to 12.

[0026] In the above formula (I), X 1 and X 2 each independently represent a hydrolyzable group. Examples of the hydrolyzable group include a hydroxyl group and an alkoxy group having 1 to 4 carbon atoms. X 1 and X 2 are preferably hydroxyl groups. When X 1 and X 2 are alkoxy groups, the above alkoxy group is preferably a methoxy group or an ethoxy group.

[0027] In the above formula (I), a and b each independently represent an integer of 0 to 2, and 0 ≦ a + b ≦ 2. Also, c and d each independently represent an integer of 0 to 2, and 0 ≦ c + d ≦ 2. It is preferable that both a + b and c + d are 0 or 1.

[0028] Specific examples of the silicon-containing compound (A) represented by the above formula (I) include bis(trimethoxysilyl)methane, 1,2-bis(trimethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethane, 1,6-bis(trimethoxysilyl)hexane, 1,6-bis(triethoxysilyl)hexane, 1,8-bis(trimethoxysilyl)octane, 1,8-bis(triethoxysilyl)octane, 1,9-bis(trimethoxysilyl)nonane, 1,9-bis(triethoxysilyl)nonane, and the like. Among these, 1,2-bis(triethoxysilyl)ethane is preferable from the viewpoints of handling safety, corrosion resistance, and adhesion of the resulting film.

[0029] In addition to those represented by the above formula (I), the silicon-containing compound (A) may be tetraethoxysilane, tetramethoxysilane, trimethoxysilylsilane, or their condensates.

[0030] The silicon-containing compound (A) may be used alone or in combination of two or more. The silicon-containing compound (A) may be partially hydrolyzed or may be condensed by hydrolysis.

[0031] The water-soluble amino group-containing compound (B) is a water-soluble compound having one or more amino groups in the molecule. The water-soluble amino group-containing compound (B) may have a silanol group in addition to the amino group.

[0032] Specific examples of the water-soluble amino group-containing compound (B) include aminosilanes such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, and 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, and amine-modified epoxy resins. The water-soluble amino group-containing compound (B) may be used alone or in combination of two or more.

[0033] The amine-modified epoxy resin can be obtained by any modification method for modifying an epoxy resin with an amine. Examples of the above modification method include a method of adding a primary amino group-containing compound to an epoxy resin, a method of adding a ketiminated amino group-containing compound to an epoxy resin, etc. Examples of the above epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, etc.

[0034] In the aqueous surface treatment agent, the total mass concentration (A + B) of the silicon-containing compound (A) and the water-soluble amino group-containing compound (B) is in the range of 1 to 30 g / L. When the total mass concentration (A + B) is less than 1 g / L, the coating of the metal substrate by the formed film becomes insufficient, resulting in a decrease in the corrosion resistance of the surface-treated metal member. When the total mass concentration (A + B) exceeds 30 g / L, liquid pooling occurs, and the portion becomes a thick film, resulting in poor appearance of the surface-treated metal member. The total mass concentration (A + B) is preferably in the range of 3 to 30 g / L.

[0035] In the aqueous surface treatment agent, the mass concentration ratio {A / (A + B)} of the silicon-containing compound (A) to the total mass concentration (A + B) of the silicon-containing compound (A) and the water-soluble amino group-containing compound (B) is in the range of 45 to 95%. Here, the concentrations used in the calculation of {A / (A + B)} both mean mass concentrations. When the concentration ratio {A / (A + B)} is less than 45%, liquid drainage occurs when the time interval from the end of the surface treatment agent contact step to the start of the drying step is long, resulting in insufficient adsorption of the aqueous surface treatment agent on the metal substrate surface and the formation of a continuous film not being possible. When the concentration ratio {A / (A + B)} exceeds 95%, the content of the water-soluble amino group-containing compound (B) decreases, resulting in a decrease in the adhesion to the topcoat film.

[0036] The aqueous surface treatment agent according to this embodiment contains water in addition to the silicon-containing compound (A) and the water-soluble amino group-containing compound (B). The water content can be an amount such that the total mass concentration (A + B) is in the range of 1 to 30 g / L. The aqueous surface treatment agent may contain substances other than the above within a range that does not impair the effects of the present invention. For example, it may also contain an organic solvent, a crosslinking agent that promotes the curing of the resin, a surface conditioner used for leveling purposes, an antifoaming agent used for defoaming purposes, and the like.

[0037] (Drying step) The drying process is a process of drying the liquid film of the metal member having a liquid film on the surface obtained by the above surface treatment agent contact process to form a film. The aqueous surface treatment agent used in the above surface treatment agent contact process is a non-reactive type, does not involve a chemical conversion reaction in the formation of the surface treatment film, and does not generate sludge. Therefore, in the manufacturing method according to the present embodiment, unlike the conventional chemical conversion treatment, it is not necessary to provide a water washing process between the surface treatment agent contact process and the drying process. For this reason, the manufacturing time and manufacturing cost of the surface-treated metal member can be reduced.

[0038] The drying temperature and drying time in the drying process are not particularly limited as long as they are the temperature and time at which unnecessary components (for example, moisture, organic solvents, etc.) in the film evaporate. For example, the drying temperature can be 100 °C and the drying time can be 10 minutes. The drying method is also not particularly limited, and for example, a commercially available hot air dryer or the like can be used. Prior to the drying process, air blowing or the like for removing the excess aqueous surface treatment agent may be performed.

[0039] The time interval from the end of the above surface treatment agent contact process to the start of the above drying process may be 30 seconds or more. The aqueous surface treatment agent according to the present embodiment can ensure preferable corrosion resistance and adhesion of the surface-treated metal member even if the time interval is long and liquid dripping or liquid pooling occurs. The time interval may be 5 minutes or more, or may be 30 minutes or more. Also, it is preferably less than 180 minutes. Here, since the surface-treated metal member is transported to the drying furnace without being heated during the period from the end of the above surface treatment agent contact process to the start of the above drying process, the temperature of the surface-treated metal member is maintained at room temperature or lower.

[0040] <Surface treatment film> The film amount of the film formed by the above aqueous surface treatment agent after the above drying process is preferably in the range of 1 to 100 g / m 2 Thereby, preferable corrosion resistance and adhesion of the surface-treated metal member can be obtained.

[0041] The manufacturing method of the surface-treated metal member according to this embodiment may optionally include other processes within the range that does not impair the effects of the present invention. For example, after the above drying process, a coating process of forming a topcoat film with a topcoat paint may be further included. The topcoat paint used in the coating process is not particularly limited, and examples include powder paints such as BI-curing type powder paints and HAA-curing type powder paints, water-based paints, solvent-based paints, and the like. The coating method in the coating process is not particularly limited, and known coating methods such as dipping method, spraying method, roll coating method, bar coating method, brush painting, roller painting, etc. can be used.

Examples

[0042] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these examples.

[0043] [Preparation of Aqueous Surface Treatment Agent] <Examples 1 to 19, Comparative Examples 1 to 8> Based on the formulations shown in Table 1 below, aqueous surface treatment agents according to each example and comparative example were prepared. The numbers indicating the blending amounts of components (A) and (B) in Table 1 mean parts by mass (solid content). In addition to the components shown in Table 1, water is contained in the aqueous surface treatment agents according to each example and comparative example. Details of the components and materials shown in Table 1 are shown below.

[0044] (A): Silicon-containing compound (A) and corresponding components A-1: 1,2-bis(triethoxysilyl)ethane (BTSE) KBE-3026 (manufactured by Shin-Etsu Chemical Co., Ltd.) A-2: Tetraethoxysilane (TEOS) KBE-04 (manufactured by Shin-Etsu Chemical Co., Ltd.) A-3: Bis(triethoxysilyl)amine Dynasylan1124 (manufactured by Evonic)

[0045] (B): Water-soluble amino group-containing compound (B) and corresponding components B-1: 3-aminopropyltrimethoxysilane KBM-903 (manufactured by Shin-Etsu Chemical Co., Ltd.) B-2: N-2-(Aminoethyl)-3-aminopropyltrimethoxysilane KBM-603 (manufactured by Shin-Etsu Chemical Co., Ltd.) B-3: N-Phenyl-3-aminopropyltrimethoxysilane KBM-573 (manufactured by Shin-Etsu Chemical Co., Ltd.) B-4: Amine-modified epoxy resin B-5: 3-Glycidoxypropyltrimethoxysilane KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0046] (B-4: Method for producing amine-modified epoxy resin) In a reaction vessel equipped with a stirrer, a cooler, a nitrogen inlet tube, and a thermometer, 702 parts of an epoxy resin with an epoxy equivalent of 188 synthesized from bisphenol A and epichlorohydrin, 269 parts of bisphenol A, 108 parts of dimer acid, and 190 parts of methyl isobutyl ketone (hereinafter referred to as "MIBK") were charged. In the presence of 1 part of benzyldimethylamine, the reaction was carried out at 117°C until the epoxy equivalent reached 1270. Then, 255 parts of a ketimine compound of aminoethylethanolamine (73% by mass MIBK solution) were added and reacted at 117°C for 1 hour. Then, it was diluted with MIBK until the non-volatile content reached 75%, and an amine-modified epoxy resin with a number average molecular weight of 2400 and an amine equivalent of 1184 was obtained. Acetic acid was added to the above amine-modified epoxy resin to achieve a neutralization rate of 20.0% (neutralization rate with respect to the amine groups of the resin), and ion-exchanged water was added for dilution. Then, the mixture of MIBK and water was removed under reduced pressure until the solid content reached 40% by mass, and an emulsion of the amine-modified epoxy resin was prepared.

[0047] (C): Metal substrate C-1: Cold-rolled steel sheet SPCC-SD (manufactured by Partec Co., Ltd.) C-2: Galvanized steel sheet GI (manufactured by Japan Test Panel Co., Ltd.) C-3: Alloy galvanized steel sheet GA (manufactured by Partec Co., Ltd.) C-4: Electro-galvanized steel sheet SECC (manufactured by Partec Co., Ltd.) C-5: Stainless steel sheet SUS316 (manufactured by Standard Test Piece Co., Ltd.)

[0048] (D): Topcoat paint D-1: BI-curing powder coating, Viryusha PL1000 (manufactured by Nippon Paint Industrial Coatings Co., Ltd.) D-2: HAA-curing powder coating, Viryusha EcoLea PL7000 (manufactured by Nippon Paint Industrial Coatings Co., Ltd.) D-3: One-component water-based paint, Audiecoline S-130 (manufactured by Nippon Paint Industrial Coatings Co., Ltd.) D-4: Urethane-based one-component solvent paint, Unipon 2700 (manufactured by Nippon Paint Industrial Coatings Co., Ltd.)

[0049] [Degreasing and water washing process] The metal substrates (C) shown in Table 1 below were each immersed in a degreasing agent (trade name "Surf Cleaner 53NF" manufactured by Nippon Paint Surf Chemicals) heated to 40°C for 120 seconds for degreasing, and then thoroughly washed with tap water to obtain degreased and water-washed metal members.

[0050] [Surface treatment agent contact process] For the above degreased and water-washed metal members, the water-based surface treatment agents according to the respective examples and comparative examples were sprayed at room temperature of 25°C for 30 seconds, bringing the metal members into contact with the water-based surface treatment agents to form a liquid film of the water-based surface treatment agent on the surfaces of the metal members.

[0051] In the above surface treatment agent contact process, the surface treatment agent was brought into contact with the metal members in a suspended state. Thereby, it is possible to evaluate the liquid sagging in the flat part and the liquid accumulation in the edge part after the surface treatment occurring in the processed and formed members. By suspending the metal members, liquid sagging can occur in the upper and middle parts of the members after contact with the surface treatment agent. Also, a liquid accumulation (a thick part of the liquid film) can be formed in the edge part which is the lowermost part. Therefore, it is possible to evaluate the liquid sagging in the flat part and the liquid accumulation in the edge part of the metal members occurring in the processed and formed members.

[0052] [Drying process] After the completion of the surface treatment agent contact step, the metal substrate was allowed to stand at room temperature for 30 minutes without heating, and then, a drying step of drying the metal substrates according to each example and comparative example in a dryer at a temperature of 100 °C was started, and the drying step was continued for 10 minutes to obtain a metal member having a surface treatment film. The average wet film amount on each steel plate 30 minutes after the treatment was 8 g / m 2 was obtained.

[0053] [Painting process] For the surface-treated metal members according to each example and comparative example that had undergone the above drying step, the topcoat paint (D) shown in Table 1 below was applied by spraying and dried to form a coating film. The following evaluations were performed on the surface-treated metal members (test panels) according to each example and comparative example on which the above coating film was formed.

[0054] [Corrosion resistance (SST) test] The test panels were subjected to a salt spray test (SST) under the conditions of JIS Z 2371:2015 for up to 500 hours. Then, a cellophane tape was attached to the cross-cut portion, the cellophane tape was peeled off, and the presence or absence of peeling from the cross-cut portion was confirmed. And the evaluation was carried out according to the following criteria. The results are shown in Table 1. 3: No peeling occurred at the time point after 500 hours. 2: No peeling occurred at the time point after 250 hours, and peeling occurred at the time point after 500 hours. 1: Peeling occurred at the time point after 250 hours.

[0055] [Film appearance evaluation] According to the following evaluation criteria, the appearance of the surface-treated metal members according to each example and comparative example after the painting process was visually evaluated. The results are shown in Table 1. 2: No abnormality 1: Appearance defect occurred

[0056]

Table 1

[0057] As shown in Table 1, it was confirmed that the surface-treated metal members according to each example had preferable corrosion resistance and film appearance as compared with the surface-treated metal members according to each comparative example.

Claims

1. A method for manufacturing a surface-treated metal member, comprising: a degreasing and water-washing step of degreasing a metal member and then washing it with water to form a degreased and water-washed metal member; a surface treatment agent contact step of bringing the degreased and water-washed metal member into contact with an aqueous surface treatment agent to form a metal member having a liquid film on its surface; and a drying step of drying the liquid film of the metal member having a liquid film on its surface to form a film. The aqueous surface treatment agent: contains a silicon-containing compound (A) that does not contain a polar functional group other than a silanol group, a water-soluble amino group-containing compound (B), and water; the mass concentration of (A + B), which is the total mass concentration of the silicon-containing compound (A) and the water-soluble amino group-containing compound (B) in the aqueous surface treatment agent, is in the range of 1 to 30 g / L; the value of the mass concentration ratio {A / (A + B)} of the silicon-containing compound (A) to the total mass concentration (A + B) of the silicon-containing compound (A) and the water-soluble amino group-containing compound (B) in the aqueous surface treatment agent is in the range of 45 to 95%. A method for manufacturing a surface-treated metal member.

2. The method for manufacturing a surface-treated metal member according to claim 1, wherein the metal member is a processed and formed member.

3. The method for manufacturing a surface-treated metal member according to claim 1, wherein the silicon-containing compound (A) is a silicon-containing compound having two or more silanol groups in one molecule.

4. The method for manufacturing a surface-treated metal member according to claim 1, wherein the silicon-containing compound (A) is 1,2-bis(triethoxysilyl)ethane.

5. The method for manufacturing a surface-treated metal member according to claim 1, wherein the water-soluble amino group-containing compound (B) is an aminosilane or an amine-modified epoxy resin.

6. The method for manufacturing a surface-treated metal member according to claim 1, wherein the time interval from the end of the surface treatment agent contact step to the start of the drying step is 30 seconds or more.

7. The amount of the film formed by the aqueous surface treatment agent after drying is in the range of 1 to 100 mg / m ２ The method for manufacturing a surface-treated metal member according to claim 1, wherein the range is within.

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