Method for manufacturing surface-treated metal parts and water-based surface treatment agent for machining molded metal parts

Abstract

Provided is a production method for surface-treated metal members, which enables reduction in the amount of chemical conversion sludge while achieving the same corrosion resistance and coating film adhesion as the prior art. A production method for surface-treated metal members, which includes: a water-washing step for degreasing, which forms a metal member obtained by water-washing for degreasing; a surface treatment agent contacting step, which brings the metal member obtained by water-washing for degreasing into contact with an aqueous surface treatment agent; and a drying step, which dries the metal member having a liquid film on the surface without water-washing. In the production method, the aqueous surface treatment agent contains a specific aqueous resin (A), a metal compound (B), a chelating agent (C), and water, and the solid content of the aqueous surface treatment agent is 0.01 to 6 mass% relative to the total mass of the aqueous surface treatment agent.

Description

TECHNICAL FIELD

[0001] The present application relates to a production method for surface-treating a metal member (i.e., "a metal member subjected to surface treatment") and an aqueous surface-treating agent for processing a molded metal member (i.e., "a metal member obtained by processing / molding"). BACKGROUND

[0002] In a case where a surface of a metal member is to be painted, the metal member before painting is generally subjected to chemical conversion treatment so as to form a chemical conversion film on the surface of the metal member, and the metal member is imparted with corrosion resistance, paint film adhesion, and the like.

[0003] As the chemical conversion treatment, a phosphate chemical conversion treatment is generally used. In recent years, however, a zirconium chemical conversion treatment which does not contain harmful heavy metals such as nickel has also been used as a chemical conversion treatment for reducing environmental impact.

[0004] For example, Patent Literature 1 discloses a surface conditioning composition used in surface conditioning of a metal before performing a phosphate chemical conversion treatment.

[0005] Patent Literature 2 discloses a metal surface treatment composition containing zirconium, fluorine, and a soluble epoxy resin.

[0006] LIST OF CITATIONS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: JP 2007-297709 A

[0009] Patent Literature 2: JP 2013-053326 A SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] However, the surface conditioning composition of Patent Literature 1 and the metal surface treatment composition of Patent Literature 2 each form a film by a chemical reaction between a surface of a metal material and a chemical conversion treatment liquid. In a surface treatment process using such a surface treatment agent, there are technical problems such as: the surface treatment agent cannot be used at normal temperature; chemical conversion sludge is generated as a byproduct; at least one or more water washing steps are required after the chemical conversion treatment; and a large amount of equipment or cost is required due to an increase in treatment time or treatment steps.

[0012] Therefore, an object of the present application is to provide a production method for surface-treating a metal member, which can reduce the amount of sludge (hereinafter also simply referred to as "chemical conversion sludge") generated in a chemical conversion reaction while achieving the same corrosion resistance and paint film adhesion as the prior art.

[0013] Further, another object of the present application is to provide a water-based surface treatment agent for processing a molded metal member, which can reduce the amount of chemical conversion sludge while achieving the same corrosion resistance and coating film adhesion as the prior art.

[0014] Technical Solution

[0015] The manufacturing method of the surface-treated metal member of the present application includes:

[0016] a degreasing water washing step of degreasing and then water washing the metal member to form a degreasing water-washed metal member;

[0017] a surface treatment agent contacting step of contacting the degreasing water-washed metal member with a water-based surface treatment agent to form a metal member having a liquid film on the surface; and

[0018] a drying step of drying the metal member having the liquid film on the surface without water washing to form a metal member having a surface treatment film, wherein

[0019] In the manufacturing method, the water-based surface treatment agent contains a water-based resin (A), a metal compound (B), a chelating agent (C), and water,

[0020] The water-based resin (A) contains one or more selected from the group consisting of a water-based epoxy resin, a water-based polyurethane resin, and a water-based silicone oligomer,

[0021] The metal compound (B) contains one or more metal elements selected from the group consisting of magnesium, aluminum, titanium, and zirconium,

[0022] The chelating agent (C) is a chelating agent having one or more first metal coordination sites selected from the group consisting of an amino group and a phosphonic acid group and one or more second metal coordination sites selected from the group consisting of a carboxyl group and a hydroxyl group in one molecule, and

[0023] The water-based surface treatment agent has a solid content in the range of 0.01 to 6 mass% with respect to the total mass of the water-based surface treatment agent.

[0024] Based on this, even if heating of a chemical conversion treatment tank or water washing after chemical conversion treatment is omitted, the same corrosion resistance and coating film adhesion as the prior art can be achieved.

[0025] In one embodiment of the manufacturing method of the present application, the water-based surface treatment agent has a solid content in the range of 0.01 to 3 mass% with respect to the total mass of the water-based surface treatment agent.

[0026] In one embodiment of the production method of the present application, the metal member is a processed molded member.

[0027] In one embodiment of the production method of the present application, the aqueous surface treatment agent has a fluorine ion content of less than 0.005 mass%.

[0028] In one embodiment of the production method of the present application, the chelating agent (C) is one or more selected from the group consisting of alcohol amines, hydroxyl group-containing organic phosphonic acid compounds, and carboxyl group-containing organic phosphonic acid compounds.

[0029] In one embodiment of the production method of the present application, when the number of equivalents of the metal element of the metal compound (B) is set as EB and the number of equivalents of the metal coordination site of the chelating agent (C) is set as EC,

[0030] The EB is in the range of 0.50 to 4.00 relative to the EC.

[0031] In one embodiment of the production method of the present application, the aqueous resin (A) is a resin having two or more groups selected from the group consisting of primary amino groups, secondary amino groups, carboxyl groups, hydroxyl groups, carbamate groups, and urea groups.

[0032] In one embodiment of the production method of the present application, the aqueous resin (A) contains one or more selected from the group consisting of acrylic-modified epoxy resins, polyurethane resins containing carbon-carbon unsaturated bonds, and polyurethane resins containing aromatic ring structures.

[0033] In one embodiment of the production method of the present application, the chelating agent (C) contains one or more selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetetraacetic acid, triethylenetetraminehexaacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid, 1-hydroxyethane-1,1-diphosphonic acid, and 2-phosphonobutane-1,2,4-butanetricarboxylic acid.

[0034] The aqueous surface treatment agent of the present application is an aqueous surface treatment agent for a processed molded metal member, which contains an aqueous resin (A), a metal compound (B), a chelating agent (C), and water, wherein

[0035] The aqueous resin (A) contains one or more selected from the group consisting of aqueous epoxy resins, aqueous polyurethane resins, and aqueous silicone oligomers,

[0036] The metal compound (B) contains one or more metal elements selected from the group consisting of magnesium, aluminum, titanium, and zirconium,

[0037] The chelating agent (C) is one or more selected from the group consisting of an alcohol amine, a hydroxyl group-containing organic phosphonic acid compound, and a carboxyl group-containing organic phosphonic acid compound,

[0038] The solid content of the aqueous surface treatment agent is in the range of 0.01 to 6 mass% with respect to the total mass of the aqueous surface treatment agent.

[0039] Based on this, even if heating of the chemical conversion treatment tank or water washing after the chemical conversion treatment is omitted, the same corrosion resistance and coating film adhesion as the prior art can be achieved.

[0040] In one embodiment of the aqueous surface treatment agent of the present application, the solid content of the aqueous surface treatment agent is in the range of 0.01 to 3 mass% with respect to the total mass of the aqueous surface treatment agent.

[0041] Advantages

[0042] Based on the present application, a manufacturing method of surface-treating a metal member can be provided, by which the amount of chemical conversion sludge can be reduced while achieving the same corrosion resistance and coating film adhesion as the prior art. Further, based on the present application, an aqueous surface treatment agent for processing a molded metal member can be provided, by which the amount of chemical conversion sludge can be reduced while achieving the same corrosion resistance and coating film adhesion as the prior art. DETAILED DESCRIPTION

[0043] Hereinafter, embodiments of the present application will be described. The following description is for the purpose of illustration only and is not intended to limit the scope of the present application in any way.

[0044] Two or more embodiments can be arbitrarily combined.

[0045] In the present specification, the terms "film" and "coating film" can be used interchangeably.

[0046] The term "solid content" is a concept including solid content, nonvolatile content, and active content.

[0047] In the present specification, unless otherwise specified, a numerical range is intended to include the upper limit value and the lower limit value of the range. For example, 0.01 to 6 mass% means a range of not less than 0.01 mass% and not more than 6 mass% (a range of 0.01 mass% or more and 6 mass% or less).

[0048] In the present specification, the aqueous resin (A), the metal compound (B), and the chelating agent (C) can be simply referred to as "A component", "B component", and "C component", respectively.

[0049] In the present specification, the surface treatment agent contacting step can also be simply referred to as "contacting step".

[0050] In the present specification, the term "primary amino group" means "-NH2", the term "secondary amino group" means ">NH", the term "carbamate group" means a structure represented by "-NH-(C=0)-0-", and the term "urea group" means a structure represented by "-NH-(C=0)-NH-".

[0051] In the present specification, "(meth)acrylic acid" means "one or more selected from the group consisting of acrylic acid and methacrylic acid".

[0052] Method for manufacturing surface-treated metal member

[0053] The method for manufacturing a surface-treated metal member of the present application includes:

[0054] a degreasing and water washing step of degreasing a metal member and then water washing the degreased metal member to form a degreased and water-washed metal member;

[0055] a surface treatment agent contacting step of contacting the degreased and water-washed metal member with an aqueous surface treatment agent to form a metal member having a liquid film on a surface thereof; and

[0056] a drying step of drying the metal member having a liquid film on a surface thereof without water washing to form a metal member having a surface treatment film, wherein

[0057] In the manufacturing method, the aqueous surface treatment agent contains an aqueous resin (A), a metal compound (B), a chelating agent (C), and water,

[0058] the aqueous resin (A) contains one or more selected from the group consisting of an aqueous epoxy resin, an aqueous polyurethane resin, and an aqueous silicone oligomer,

[0059] the metal compound (B) contains one or more metal elements selected from the group consisting of magnesium, aluminum, titanium, and zirconium,

[0060] the chelating agent (C) is a chelating agent having one or more first metal coordination sites selected from the group consisting of an amino group and a phosphonic acid group and one or more second metal coordination sites selected from the group consisting of a carboxyl group and a hydroxyl group in one molecule, and

[0061] the aqueous surface treatment agent has a solid content in a range of 0.01 to 6 mass% with respect to the total mass of the aqueous surface treatment agent.

[0062] Next, each step of the method for manufacturing a surface-treated metal member of the present application will be described.

[0063] Degreasing and water washing step

[0064] In the degreasing water washing step, the metal member is subjected to degreasing and then water washing to thereby form a degreased and water washed metal member. By the degreasing, oil (oil content) and / or dirt adhering to the surface of the metal member are removed. In addition, by the water washing after the degreasing, the degreasing agent remaining on the surface of the metal member after the degreasing treatment is removed.

[0065] Any publicly known metal member can be used as the above-mentioned metal member without any particular limitation. For example, the metal member can be an iron-based substrate, an aluminum-based substrate, a zinc-based substrate, a magnesium-based substrate, or the like. The iron-based substrate is a substrate selected from one or more of the group consisting of iron and iron alloys. The aluminum-based substrate is a substrate selected from one or more of the group consisting of aluminum and aluminum alloys. The zinc-based substrate is a substrate selected from one or more of the group consisting of zinc and zinc alloys. The magnesium-based substrate is a substrate selected from one or more of the group consisting of magnesium and magnesium alloys.

[0066] In one embodiment of the production method of the present application, the metal member is a processed molded member. As the processed molded member, for example, a member obtained by processing / molding such as laser processing, press processing, or the like can be exemplified.

[0067] The degreasing method is not particularly limited. For example, the degreasing agent and the degreasing conditions described in Patent Document 2 can be employed.

[0068] Surface treatment agent contacting step

[0069] In the surface treatment agent contacting step, the degreased and water washed metal member is contacted with the aqueous surface treatment agent to thereby form a metal member having a liquid film on the surface.

[0070] Aqueous surface treatment agent

[0071] The aqueous surface treatment agent used in the production method of the present application contains an aqueous resin (A), a metal compound (B), a chelating agent (C), and water, wherein

[0072] The aqueous resin (A) contains one or more selected from the group consisting of an aqueous epoxy resin, an aqueous polyurethane resin, and an aqueous silicone oligomer,

[0073] The metal compound (B) contains one or more metal elements selected from the group consisting of magnesium, aluminum, titanium, and zirconium,

[0074] The chelating agent (C) is a chelating agent having one or more first metal coordination sites selected from the group consisting of an amino group and a phosphonic acid group and one or more second metal coordination sites selected from the group consisting of a carboxyl group and a hydroxyl group in one molecule, and

[0075] The solid content of the aqueous surface treatment agent is in the range of 0.01 to 6 mass% relative to the total mass of the aqueous surface treatment agent.

[0076] • A component

[0077] The A component contains one or more selected from the group consisting of an aqueous epoxy resin, an aqueous polyurethane resin, and an aqueous silicone oligomer. From the viewpoint of the corrosion resistance of the chemical conversion treatment film with respect to the metal member, it is preferable that the A component be an aqueous epoxy resin.

[0078] One example of a preferable form of the aqueous epoxy resin is an acrylic-modified epoxy resin. By containing an acrylic-modified epoxy resin, it is advantageous in ensuring good adhesion of the chemical conversion treatment film to the metal member.

[0079] Examples of commercial products of the acrylic-modified epoxy resin include "MODEPICS 301", "MODEPICS 302", "MODEPICS 303", "MODEPICS 304" (trade names) manufactured by Arakawa Chemical Industries, and the like.

[0080] In addition to the above examples, an aqueous epoxy resin described in Patent Literature 1, JP 2005-008975 A, and the like, for example, can be used as the aqueous epoxy resin.

[0081] One aqueous epoxy resin can be used alone or two or more aqueous epoxy resins can be used in combination.

[0082] The aqueous polyurethane resin is not particularly limited, and can be, for example, an aqueous polyurethane resin described in JP 2005-008975 A, and the like.

[0083] In one embodiment, the A component includes one or more selected from the group consisting of a carbon-carbon unsaturated bond and an aromatic ring structure in its molecule.

[0084] In one embodiment of the production method of the present application, the aqueous resin (A) is a resin including two or more groups selected from the group consisting of a primary amino group (-NH2), a secondary amino group (>NH), a carboxyl group, a hydroxyl group, a urethane group, and a urea group. From the viewpoint of improving the corrosion resistance of the chemical conversion treatment film, it is preferable that the resin contain two or more of the functional groups.

[0085] The aqueous polyurethane resin is not particularly limited, and examples thereof are products obtained by reacting a polyol compound with a diisocyanate compound and further performing chain extension using a diamine or the like, and then dispersing in water.

[0086] Commercially available products can be used as the water-based polyurethane resin. Examples of the commercially available products include: HUX-320, HUX-550 (trade names) manufactured by ADEKA Corporation, SUPERFLEX (registered trademark in Japan, other countries, or both) manufactured by DKS Co., Ltd., and "HYDRAN" (registered trademark in Japan, other countries, or both) manufactured by DIC Corporation, and the like.

[0087] One water-based polyurethane resin can be used alone, or two or more water-based polyurethane resins can be used in combination.

[0088] The water-based silicone oligomer is not particularly limited, and can be, for example, the silicone oligomer (A) described in JP6058843B1, or the like.

[0089] Commercially available products can be used as the silicone oligomer. Examples of the commercially available products include: methyimethoxy type oligomers such as KC-89, KR-500, X-40-9225, X-40-9246, and X-40-9250 (trade names) manufactured by Shin-Etsu Chemical Co., Ltd., phenylmethoxy type oligomers such as KR-217 (trade name), and condensates of amino silane oligomers such as KBM-903 (trade name), and methy / phenylmethoxy type oligomers such as KR-9218, KR-213, KR-510, X-40-9227, X-40-9247, KR-401N (trade name), methyimethoxy type oligomers such as MSE-100 (trade name) manufactured by Wacker silicone Co., Ltd., and the like.

[0090] One water-based silicone oligomer can be used alone, or two or more water-based silicone oligomers can be used in combination.

[0091] In one embodiment of the production method of the present application, the water-based resin (A) contains one or more selected from the group consisting of an acrylic-modified epoxy resin, a polyurethane resin containing a carbon-carbon unsaturated bond, and a polyurethane resin containing an aromatic ring structure.

[0092] The amount of the component A can be appropriately adjusted, and can be, for example, 20 to 80 mass% with respect to the total solid content in the water-based surface treatment agent. In one embodiment, the amount of the component A is 20 mass% or more, 30 mass% or more, 40 mass% or more, 50 mass% or more, 60 mass% or more, or 70 mass% or more with respect to the total solid content in the water-based surface treatment agent. In another embodiment, the amount of the component A is 80 mass% or less, 70 mass% or less, 60 mass% or less, 50 mass% or less, 40 mass% or less, or 30 mass% or less with respect to the total solid content in the water-based surface treatment agent.

[0093] B component

[0094] The B component contains one or more metal elements selected from the group consisting of magnesium, aluminum, titanium, and zirconium. The B component functions together with the A component to impart good corrosion resistance.

[0095] The B component may, for example, be a carbonate, a phosphate, a nitrate, a sulfate, an acetate, an oxide, a hydroxide, an organic acid salt, a complex, or the like of any of the above metal elements. The B component can be a simple salt or a double salt.

[0096] Examples of the B component containing magnesium include magnesium nitrate, magnesium sulfate, magnesium acetate, and magnesium oxide.

[0097] Examples of the B component containing aluminum include aluminum nitrate, aluminum sulfate, aluminum acetate, and aluminum oxide.

[0098] Examples of the B component containing titanium include titanium nitrate, titanium oxynitrate, titanium oxysulfate, titanium sulfate, titanium oxide, titanium diisopropoxide bis(acetylacetonate), a reaction product of lactic acid and a titanium alkoxide, titanium laurate, titanium acetylacetonate, and barium titanate.

[0099] Examples of the B component containing zirconium include zirconium oxynitrate, zirconium oxylate, zirconium acetate, zirconium sulfate, zirconium oxysulfate, titanium sulfate, zirconium sulfate hydrate, zirconium oxyphosphate, zirconium phosphate, sodium zirconium phosphate, ammonium zirconium oxycarbonate, ammonium zirconium carbonate, potassium zirconium carbonate, zirconium carbonate hydrate, zirconium oxide, zirconium hydroxide, zirconium acetylacetonate, and calcium zirconate.

[0100] As the B component, a metal compound containing zirconium can be appropriately used, and for example, ammonium zirconium carbonate, potassium zirconium carbonate, or the like can be appropriately used in particular.

[0101] One B component can be used alone, or two or more B components can be used in combination.

[0102] The amount of the B component can be appropriately adjusted, and for example, can be 10 to 70% by mass with respect to the total solid content in the aqueous surface treatment agent. In one embodiment, the amount of the B component is 10% by mass or greater, 20% by mass or greater, 25% by mass or greater, 30% by mass or greater, 40% by mass or greater, 50% by mass or greater, or 60% by mass or greater with respect to the total solid content in the aqueous surface treatment agent. In another embodiment, the amount of the B component is 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, or 20% by mass or less with respect to the total solid content in the aqueous surface treatment agent.

[0103] In one embodiment of the production method of the present application, when the number of equivalents of the metal element of the metal compound (B) is set as EB and the number of equivalents of the metal coordination site of the chelating agent (C) is set as EC, the EB is in the range of 0.50 to 4.00 with respect to the EC.

[0104] One example of calculating EB with respect to EC is further explained based on the following Example 1. Zirconium ammonium carbonate (NH4)2ZrO(C03)2 as the B component is treated as 263.33 g / mol, and diethanolamine is treated as 105.14 g / mol. In Example 1, 99.6 parts by mass of (NH4)2ZrO(C03)2 corresponds to 99.6 / 263.33 = 0.378 mol = 378 mmol. Note that since 1 mol of Zr is included in 1 mol of (NH4)2ZrO(C03)2, EB is 378 mmol. On the other hand, 9.9 parts by mass (as the active ingredient) of diethanolamine in Example 1 corresponds to 9.9 / 105.14 = 0.0942 mol = 94.2 mmol. Since the number of metal coordination sites in diethanolamine is 3 (2 of hydroxyl groups and 1 of NH group), the number of moles of metal coordination sites (i.e., EC) is 94.2 mmol x 3 = 282.6 mmol. Thus, EB / EC = 378 / 282.6 = 1.337 = about 1.34.

[0105] C component

[0106] The C component is a chelating agent having one or more first metal coordination sites selected from the group consisting of an amino group and a phosphonic acid group, and one or more second metal coordination sites selected from the group consisting of a carboxyl group and a hydroxyl group in one molecule.

[0107] Examples of the chelating agent that can be preferably used include an alcohol amine, a hydroxyl group-containing organic phosphonic acid compound, and a carboxyl group-containing organic phosphonic acid compound.

[0108] Examples of the alcohol amine include monoethanolamine, diethanolamine, triethanolamine, N-butylethanolamine, N-methylethanolamine, 2-amino-2-methyl-l-propanol, dimethylethanolamine, dibutylethanolamine, and methyldiethanolamine.

[0109] Examples of the hydroxyl group-containing organic phosphonic acid compound include hydroxymethanediphosphonic acid, 1-hydroxyethane-l,l-diphosphonic acid, and 1-hydroxypropane-l,l-diphosphonic acid.

[0110] Examples of the carboxyl group-containing organic phosphonic acid compound include 2-hydroxyphosphonooxyacetic acid and 2-phosphonobutane-l,2,4-butanetricarboxylic acid.

[0111] In one embodiment of the production method of the present application, the chelating agent (C) is one or more selected from the group consisting of alcohol amines, hydroxyl group-containing organic phosphonic acid compounds, and carboxyl group-containing organic phosphonic acid compounds.

[0112] Alcohol amines can be particularly suitable for use as the C component.

[0113] In one embodiment of the production method of the present application, the chelating agent (C) contains one or more selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetetraacetic acid, triethylenetetraminehexaacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid, 1-hydroxyethane-1,1-diphosphonic acid, and 2-phosphonobutane-1,2,4-butanetricarboxylic acid.

[0114] One C component can be used alone, or two or more C components can be used in combination.

[0115] The amount of the C component can be appropriately adjusted, and can be, for example, 2 to 30 mass% with respect to the total solid content in the aqueous surface treatment agent. In one embodiment, the amount of the C component is 2 mass% or more, 5 mass% or more, 10 mass% or more, 15 mass% or more, 20 mass% or more, or 25 mass% or more with respect to the total solid content in the aqueous surface treatment agent. In another embodiment, the amount of the C component is 30 mass% or less, 25 mass% or less, 20 mass% or less, 15 mass% or less, 10 mass% or less, or 5 mass% or less with respect to the total solid content in the aqueous surface treatment agent.

[0116] The aqueous surface treatment agent contains water. The amount of water can be set to an amount in the range of 0.01 to 6 mass% of the solid content in the aqueous surface treatment agent with respect to the total mass of the aqueous surface treatment agent. The aqueous surface treatment agent can contain an organic solvent to the extent that does not impair the effects of the present application.

[0117] The solid content of the aqueous surface treatment agent is an amount in the range of 0.01 to 6 mass% with respect to the total mass of the aqueous surface treatment agent. The solid content can be preferably 0.1 to 3 mass% or 0.1 to 1 mass%.

[0118] The aqueous surface treatment agent can be an aqueous surface treatment agent that does not contain fluoride ions. Alternatively, the aqueous surface treatment agent can contain fluoride ions as an unavoidable impurity.

[0119] In one embodiment of the production method of the present application, the aqueous surface treatment agent does not contain fluoride ions or contains fluoride ions as an unavoidable impurity.

[0120] The method of bringing the defatted and water-washed metal member into contact with the aqueous surface treatment agent can be dipping, spraying, roll coating, bar coating, or the like, but is not limited thereto. Alternatively, the aqueous surface treatment agent can be allowed to flow freely and come into contact with the defatted and water-washed metal member.

[0121] There is no particular limitation on the conditions of temperature and time for the defatted and water-washed metal member to come into contact with the aqueous surface treatment agent. The temperature of the aqueous surface treatment agent during the contact can be set to a temperature of 10°C to 40°C, for example, the same as the outside air temperature. The time for the contact can be freely set depending on conditions such as the equipment and members employed, and can be set to 10 seconds to 30 seconds, for example.

[0122] In the present application, by using the above-described aqueous surface treatment agent, a lower temperature (e.g., room temperature) than the temperature set for the aqueous surface treatment agent in the contact step in general can be employed. In the case where the aqueous surface treatment agent freezes in a cold environment, heating can be performed to the minimum extent necessary for the aqueous surface treatment agent to melt, but the aqueous surface treatment agent need not be heated in a normal environment. In one embodiment, the contact step is performed without a heating means for maintaining the temperature of the aqueous surface treatment agent at 40°C or higher, 38°C or higher, or 35°C or higher.

[0123] The solid content in the liquid film formed on the surface of the metal member in the contact step can be in the range of 0.01 mass% to 6 mass%, for example.

[0124] The solid content in the liquid film formed in the surface treatment agent contact step is in the range of 0.01 mass% to 6 mass% in any case.

[0125] Drying Step

[0126] In the drying step, the metal member having the liquid film on the surface is dried without water washing to form a metal member having a surface treatment film. By performing the drying without water washing, the cost of waste water and the cost of industrial waste can be reduced. Furthermore, sludge is not generated in the chemical conversion reaction.

[0127] In the past, in order to avoid the following three problems that occur when water washing is not performed, water washing was performed in the reaction-type chemical conversion treatment. The first problem is that the reactive chemical conversion treatment liquid remains on the surface of the metal member, thereby making it impossible to control the film reaction and making it impossible to obtain the target film. The second problem is that the typical reaction-type chemical conversion treatment agent is acidic and when it remains on the surface of the metal member such as a steel sheet, it causes the formation of manufacturing rust. The third problem is that the reaction-type chemical conversion treatment causes the formation of chemical conversion sludge during the treatment and the sludge adheres to the surface of the metal member, thereby causing the appearance of the coating after the chemical conversion to be abnormal.

[0128] In contrast, the aqueous surface treatment agent used in the present application is a non-reactive agent, and thus a chemical conversion reaction does not occur in the formation of the surface treatment film. Since a chemical conversion reaction does not occur, sludge is not generated in the chemical conversion reaction. Therefore, in the manufacturing method of the present application, water washing that is required in the past reaction-type chemical conversion treatment described above becomes unnecessary.

[0129] The drying temperature and drying time after the surface treatment agent is applied are not particularly limited, and any temperature and time can be used as long as the temperature and time are such that the unnecessary components (e.g., water and / or organic solvent) can be evaporated from the film. For example, a method in which drying is performed for 3 minutes in a 100°C dryer using a hot air dryer (e.g., PHH-202 manufactured by ESPEC Corporation) can be used. In addition, drying can be performed after excess treatment liquid is removed by blowing or the like, as necessary, before drying.

[0130] The dry film thickness of the surface treatment film formed by drying is not particularly limited, and for example, can be 0.001 μm to 1.0 μm. In one embodiment, the dry film thickness of the surface treatment film is 0.002 μm to 1.0 μm or 0.002 μm to 0.5 μm. In another embodiment, the dry film thickness of the surface treatment film is 0.002 μm or more, 0.005 μm or more, 0.010 μm or more, 0.050 μm or more, 0.100 μm or more, 0.500 μm or more, or 1.000 μm or more. In another embodiment, the dry film thickness of the surface treatment film is 2.000 μm or less, 1.000 μm or less, 0.500 μm or less, 0.100 μm or less, 0.050 μm or less, 0.010 μm or less, or 0.005 μm or less.

[0131] Other Steps

[0132] In the production method of the surface-treated metal member of the present application, in addition to the steps of degreasing and water washing, the contact step, and the drying step, other steps can be optionally included. As the other steps, for example, a coating step of applying a coating composition to the metal member or the surface-treated film to form a coating film after the drying step can be included.

[0133] The coating composition used in the coating step is not particularly limited and can be appropriately selected depending on the use or the like.

[0134] The coating method used in the coating step can be a publicly known coating method such as dipping, spraying, roll coating, bar coating, brushing, or roll coating, without any particular limitation. In one embodiment, the coating method in the coating step is a spraying method (spray coating).

[0135] (Aqueous surface treatment agent)

[0136] The aqueous surface treatment agent of the present application is an aqueous surface treatment agent for processed molded metal members, which comprises an aqueous resin (A), a metal compound (B), a chelating agent (C), and water, wherein

[0137] The aqueous resin (A) comprises one or more selected from the group consisting of an aqueous epoxy resin, an aqueous polyurethane resin, and an aqueous silicone oligomer,

[0138] The metal compound (B) comprises one or more metal elements selected from the group consisting of magnesium, aluminum, titanium, and zirconium,

[0139] The chelating agent (C) is one or more selected from the group consisting of an alcohol amine, a hydroxyl group-containing organic phosphonic acid compound, and a carboxyl group-containing organic phosphonic acid compound,

[0140] The solid content of the aqueous surface treatment agent is in the range of 0.01 to 6 mass% with respect to the total mass of the aqueous surface treatment agent.

[0141] The aqueous surface treatment agent described in the contacting step of the production method for the above surface-treated metal member (hereinafter also referred to as "first aqueous surface treatment agent") differs from the aqueous surface treatment agent of the present application (hereinafter also referred to as "second aqueous surface treatment agent") in the range of the C component, but is the same in other components and amounts, etc. More specifically, the C component in the first aqueous surface treatment agent is a chelating agent having one or more first metal coordination sites selected from the group consisting of amino groups and phosphonic acid groups, and one or more second metal coordination sites selected from the group consisting of carboxyl groups and hydroxyl groups, in one molecule; in contrast, the C component in the second aqueous surface treatment agent is one or more selected from the group consisting of alcohol amines, hydroxyl group-containing organic phosphonic acid compounds, and carboxyl group-containing organic phosphonic acid compounds. Thus, the C component in the first aqueous surface treatment agent is a more general concept compared to the C component in the second aqueous surface treatment agent.

[0142] As the one or more selected from alcohol amines, hydroxyl group-containing organic phosphonic acid compounds, and carboxyl group-containing organic phosphonic acid compounds constituting the C component in the second aqueous surface treatment agent, the same as described above for the C component in the first aqueous surface treatment agent.

[0143] The second aqueous surface treatment agent is used for surface treatment of processed molded metal members. As the processed molded metal members, for example, metal members obtained by processing / molding such as laser processing, press processing, etc. can be cited.

[0144] In the aqueous surface treatment agent of the present application, in addition to the A component to the C component, additives such as typical organic and inorganic rust preventives and surface conditioning agents, etc. can be used within a range that does not impair the object. As examples of such additives, imidazoles and benzotriazoles are included.

[0145] Examples

[0146] Hereinafter, the present application will be described in further detail by citing examples. However, these examples are intended to illustrate and are not intended to limit the scope of the present application in any way.

[0147] The materials of the aqueous surface treatment agent used in the examples are described below.

[0148] A component

[0149] Aqueous epoxy resin: EPICLON H-502-42W (trade name) manufactured by DIC Corporation (EPICLON is a registered trademark in Japan, other countries, or both), aqueous modified phenoxy resin, solid content of 39 to 43 mass%, including hydroxyl groups and carboxyl groups, labeled as "EPICLON" in Tables 1 and 2

[0150] Aqueous epoxy resin: MODEPICS 301 (trade name) manufactured by Arakawa Chemical Industries, Ltd. (MODEPICS is a registered trademark in Japan, other countries, or both), solid content of 32 to 34%, including hydroxyl and carboxyl groups, labeled as "MODEPICS" in Tables 1 and 2

[0151] Aqueous polyurethane resin: HUX-320 (trade name) manufactured by ADEKA Corporation, solid content of 30 to 34%, polyurethane resin containing aromatic ring- containing structures of urethane groups and carboxyl groups, labeled as "HUX320" in Table 1

[0152] Aqueous polyurethane resin: HUX550 (trade name) manufactured by ADEKA Corporation, solid content of 26.5 to 29.5%, polyurethane resin containing aromatic ring- containing structures of urethane groups and carboxyl groups, labeled as "HUX550" in Table 1

[0153] Aqueous silicone oligomer: a solution of a hydrolysis condensate of KBM-903 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd., solid content of 20%, including hydroxyl and primary amino groups, labeled as "903 condensate" in Table 1

[0154] Comparative A component

[0155] Acrylic resin: NP-900A (trade name) manufactured by Saiden Chemical Industry Co., Ltd., solid content of 47 to 49%, labeled as "900A" in Table 2

[0156] B component

[0157] Ammonium zirconium carbonate: Zircosol AC-7 (trade name) manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd., (NH4)2ZrO(CO3)2, solid content of 29%, labeled as "AC-7" in Tables 1 and 2

[0158] Zirconyl nitrate: EKZ-5 (trade name) manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd., ZrO(NO3)2, solid content of 40%, labeled as "ZN" in Table 1

[0159] Titanium bis(triethanolamine) diisopropoxide: ORGATIX TC-400 (trade name) manufactured by Matsumoto Fine Chemical Co., Ltd., Ti(O-i-C3H7)2(C6H 14 O3N)2, solid content 79%, labeled as "TC400" in Table 1

[0160] Aluminum acetate: Basic aluminum acetate (reagent) manufactured by FUJIFILM Wako Pure Chemical Corporation, Al(OH)(CH3COO)2, solid content 100%, labeled as "aluminum acetate" in Table 1

[0161] Magnesium oxide: Magnesium oxide (reagent) manufactured by FUJIFILM Wako Pure Chemical Corporation, MgO, solid content 100%, labeled as "MgO" in Table 1

[0162] C component

[0163] Diethanolamine: Diethanolamine (reagent) manufactured by FUJIFILM Wako Pure Chemical Corporation, alcohol amine, molecular weight 105.14, including one amino group as a first metal coordination site and two hydroxyl groups as second metal coordination sites, active ingredient concentration 99% or more, labeled as "diethanolamine" in Tables 1 and 2

[0164] Triethanolamine: 2,2',2"-Nitrilotriethanol (reagent) manufactured by FUJIFILM Wako Pure Chemical Corporation, alcohol amine, molecular weight 149.19, including one amino group as a first metal coordination site and three hydroxyl groups as second metal coordination sites, active ingredient concentration 98% or more, labeled as "triethanolamine" in Tables 1 and 2

[0165] 1-Hydroxyethane-1,1-diphosphonic acid: PH-210 (trade name) manufactured by CHELEST Corporation, molecular weight 206.03, including two phosphonic acid groups as first metal coordination sites and one hydroxyl group as a second metal coordination site, solid content 60%, labeled as "HEDP" in Table 1

[0166] 2-Phosphonobutane-1,2,4-tricarboxylic acid: PH-430 (trade name) manufactured by CHELEST Corporation, molecular weight 270.13, including one phosphonic acid group as a first metal coordination site and three carboxyl groups as second metal coordination sites, solid content 50%, labeled as "PBTC" in Table 1

[0167] Comparison of component C

[0168] Citric acid: Manufactured by Fujifilm and Kojun Chemical Co., Ltd., with a molecular weight of 192.123 and a solid content of 100%, it is labeled "CA" in Table 2.

[0169] Acetylacetone: Manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd., with a molecular weight of 100.117 and an active ingredient concentration of over 99%, it is labeled "AA" in Table 2.

[0170] Zinc phosphate treatment surface treatment agent: SURFDINE 6350 (trade name) manufactured by Nippon Paint Surf Chemicals Co., Ltd.

[0171] Other materials are described below.

[0172] Degreasing agent: SURFCLEANER 53NF (trade name) manufactured by Nippon Paint Surface Treatment Co., Ltd.

[0173] Surface conditioner: SURFFINE GL1 (trade name) manufactured by Nippon Paint Surface Treatment Co., Ltd.

[0174] Powder coating: Biryusia PL1000 (trade name) manufactured by Nippon Paint Industrial Coatings Co., Ltd.

[0175] Metal components: Cold-rolled steel sheet (Paltec SPC270D)

[0176] Cellophane tape: Manufactured by Nichiban Co., Ltd. (Cellotape is a trademark registered in Japan, other countries, or both).

[0177] Examples 1 to 17 and Comparative Examples 1 to 3

[0178] Aqueous surface treatment agents were prepared by mixing each component with water according to the formulation shown in Tables 1 and 2. The amounts of each component are parts by mass of solid content. The solid content in the aqueous surface treatment agent is also shown in Table 1 or Table 2. In addition, the equivalent number EB of the metal element in component B relative to the equivalent number EC of the metal coordination site in component C is also shown in Tables 1 and 2. Fluoride ions were not added in the preparation of the aqueous surface treatment agents of Examples 1 to 17 and Comparative Examples 1 to 3.

[0179] As the surface treatment agent of Comparative Example 4, SURFDINE 6350, which is a surface treatment agent for zinc phosphate treatment, was used.

[0180] Table 1

[0181]

[0182] Table 2

[0183]

[0184] Degreasing and water washing step

[0185] A cold-rolled steel sheet to be used as a metal member was immersed in a degreasing agent for 120 seconds, the degreasing agent was heated to a temperature of 40°C to perform degreasing, and then the degreasing agent was sufficiently water washed with tap water to obtain a metal member subjected to degreasing and water washing.

[0186] Surface treatment agent contacting step

[0187] The aqueous surface treatment agent prepared in Example 1 was sprayed on the metal member subjected to degreasing and water washing at room temperature (25°C) for 30 seconds without heating to contact the metal member with the aqueous surface treatment agent and form a liquid film of the aqueous surface treatment agent on the surface of the metal member.

[0188] Drying step

[0189] The metal member having the liquid film on the surface was dried in a drier at a temperature of 100°C without water washing to obtain a metal member having a surface treatment film. The dry film thickness of the surface treatment film was 0.06 μm.

[0190] Coating step

[0191] Next, a powder coating was applied to the surface treatment film by spraying so that the dry film thickness was at least 60 μm and dried to form a coating film.

[0192] In Examples 2 to 17 and Comparative Examples 1 to 3, the above four steps were performed in the same manner as in Example 1 to sequentially form a surface treatment film and a coating film from the metal member side, except that the aqueous surface treatment agent of Example 1 was replaced with the aqueous surface treatment agent of the example or comparative example. The dry film thickness of the surface treatment film was in the range of 0.002 μm to 0.5 μm in each example except for Example 17. The dry film thickness of the surface treatment film in Example 17 was in the range of 0.002 μm to 1.0 μm.

[0193] In Comparative Example 4, the degreasing and water washing steps were performed in the same manner as in Example 1. Next, surface adjustment treatment was performed using a surface adjustment agent by immersion for 30 seconds at room temperature. Next, chemical conversion treatment was performed using a zinc phosphate treatment agent by immersion for 2 minutes at 35°C. Next, after sufficient water washing treatment using tap water, sufficient water washing treatment was performed in the same manner using pure water. Next, a drying step and a coating step were performed in the same manner as in Example 1 to form a surface treatment film and a coating film in that order from the metal member side. The dry film thickness of the surface treatment film was 2 μm. In Comparative Example 4, sludge was formed during the chemical conversion treatment using the zinc phosphate treatment agent.

[0194] The metal members with the surface treatment film and the coating film obtained in each of the examples and comparative examples were subjected to the tests described below to evaluate corrosion resistance and coating film adhesion. The results are shown in Tables 1 and 2.

[0195] Preparation of corrosion resistance test panels

[0196] A cross-shaped crosscut (cut length: 5 cm) was made on the surface of the coating film of the metal member to prepare a test panel.

[0197] Corrosion resistance (SST) test

[0198] The test panel was subjected to a salt spray test (SST) for 500 hours under the conditions of Japanese Industrial Standard JIS Z 2371:2015. Next, a glass tape was attached to the crosscut portion, the glass tape was peeled, and the maximum peeling width from one side of the crosscut portion was measured. Scores were assigned based on the following criteria. A score of 4 or 5 is a pass.

[0199] 5 points: no peeling

[0200] 4 points: peeling, maximum peeling width less than 3 mm

[0201] 3 points: maximum peeling width 3 mm or more and less than 5 mm

[0202] 2 points: maximum peeling width 5 mm or more and less than 10 mm

[0203] 1 point: maximum peeling width 10 mm or more

[0204] Corrosion resistance (CCT) test

[0205] A cyclic corrosion test (CCT) was performed on the test panel under the conditions of Japanese Automotive Standard Organization JASO M609 for 500 hours. Measurement was performed on the maximum blistering width from the cross-cut portion. Scores were assigned based on the following criteria. A score of 4 or 5 was acceptable.

[0206] 5 points: Blistering was observed, and the maximum blistering width was less than 3 mm

[0207] 4 points: The maximum blistering width was 3 mm or more and less than 5 mm

[0208] 3 points: The maximum blistering width was 5 mm or more and less than 7 mm

[0209] 2 points: The maximum blistering width was 7 mm or more and less than 10 mm

[0210] 1 point: The maximum blistering width was 10 mm or more

[0211] Corrosion resistance (SDT) test

[0212] A salt dip test (SDT) was performed on the test panel under the conditions of 25°C and a 3% NaCl concentration in brine for 500 hours. Next, measurement was performed on the maximum peeling width on one side from the cross-cut portion in the same manner as in the SST test. Scores were assigned based on the following criteria. A score of 4 or 5 was acceptable.

[0213] 5 points: No peeling

[0214] 4 points: Peeling was observed, and the maximum peeling width was less than 3 mm

[0215] 3 points: The maximum peeling width was 3 mm or more and less than 5 mm

[0216] 2 points: The maximum peeling width was 5 mm or more and less than 10 mm

[0217] 1 point: The maximum peeling width was 10 mm or more

[0218] Preparation of test panel for coating film adhesion

[0219] A test panel was prepared by applying grid-shaped scratches at 1 mm intervals on the coating film surface of the metal member to form 100 squares.

[0220] Coating film adhesion test

[0221] A glass tape was attached to the scratched portion of the test panel. The glass tape was peeled off, and the number of 1 mm square coating films remaining on the test panel without being peeled off was measured. Scores were assigned based on the following criteria. A score of 4 or 5 is acceptable.

[0222] 5 points: the number of remaining coating films is 100

[0223] 4 points: the number of remaining coating films is 80 or more but less than 100

[0224] 3 points: the number of remaining coating films is 60 or more but less than 80

[0225] 2 points: the number of remaining coating films is 40 or more but less than 60

[0226] 1 point: the number of remaining coating films is less than 40

[0227] Storage stability test

[0228] The aqueous surface treatment agents obtained in the examples and comparative examples and the zinc phosphate treatment surface treatment agent of Comparative Example 4 were each left to stand in a 40°C thermostat for 30 days. Then, the presence or absence of gelation or precipitates in the treatment agents was visually observed and evaluated according to the following criteria. The results are shown in Tables 1 and 2.

[0229] Acceptable: no gelation and precipitates

[0230] Unacceptable: gelation or precipitates

[0231] Based on the present application, it is possible to provide a manufacturing method of surface-treated metal parts, by which it is possible to reduce the amount of chemical conversion sludge while achieving the same corrosion resistance and coating film adhesion as the prior art. In addition, based on the present application, it is possible to provide an aqueous surface treatment agent for processing molded metal parts, by which it is possible to reduce the amount of chemical conversion sludge while achieving the same corrosion resistance and coating film adhesion as the prior art.

[0232] Industrial applicability

[0233] Based on the present application, it is possible to provide a manufacturing method of surface-treated metal parts, by which it is possible to reduce the amount of chemical conversion sludge while achieving the same corrosion resistance and coating film adhesion as the prior art. In addition, based on the present application, it is possible to provide an aqueous surface treatment agent for processing molded metal parts, by which it is possible to reduce the amount of chemical conversion sludge while achieving the same corrosion resistance and coating film adhesion as the prior art.

Claims

1. A production method of a surface-treated metal member, comprising: a degreasing water washing step of degreasing a metal member and then water washing to form a degreasing water washed metal member; a surface treatment agent contacting step of contacting the degreasing water washed metal member with an aqueous surface treatment agent to form a metal member having a liquid film on a surface thereof; and a drying step of drying the metal member having the liquid film on the surface thereof without water washing to form a metal member having a surface treatment film, wherein in the production method, the aqueous surface treatment agent contains an aqueous resin (A), a metal compound (B), a chelating agent (C), and water, the aqueous resin (A) contains one or more selected from the group consisting of an aqueous epoxy resin, an aqueous polyurethane resin, and an aqueous silicone oligomer, the metal compound (B) contains one or more metal elements selected from the group consisting of magnesium, aluminum, titanium, and zirconium, the chelating agent (C) is a chelating agent having one or more first metal coordination sites selected from the group consisting of an amino group and a phosphonic acid group and one or more second metal coordination sites selected from the group consisting of a carboxyl group and a hydroxyl group in one molecule, and a solid content of the aqueous surface treatment agent is in the range of 0.01 to 6 mass% with respect to a total mass of the aqueous surface treatment agent.

2. The production method according to claim 1, wherein a solid content of the aqueous surface treatment agent is in the range of 0.01 to 3 mass% with respect to a total mass of the aqueous surface treatment agent.

3. The production method according to claim 1 or 2, wherein the metal member is a processed molded member.

4. The production method according to claim 1 or 2, wherein the aqueous surface treatment agent does not contain a fluoride ion or contains a fluoride ion as an unavoidable impurity.

5. The production method according to claim 1 or 2, wherein the chelating agent (C) is one or more selected from the group consisting of an alcohol amine, a hydroxyl group-containing organophosphonic acid compound, and a carboxyl group-containing organophosphonic acid compound.

6. The production method according to claim 1 or 2, wherein when a number of equivalents of the metal elements of the metal compound (B) is set to EB and a number of equivalents of the metal coordination sites of the chelating agent (C) is set to EC, the EB is in the range of 0.50 to 4.00 with respect to the EC.

7. The production method according to claim 1 or 2, wherein the aqueous resin (A) is a resin having two or more groups selected from the group consisting of a primary amino group, a secondary amino group, a carboxyl group, a hydroxyl group, a carbamate group, and a urea group.

8. The production method according to claim 1 or 2, wherein the aqueous resin (A) contains one or more selected from the group consisting of an acrylic-modified epoxy resin, a polyurethane resin containing a carbon-carbon unsaturated bond, and a polyurethane resin containing an aromatic ring structure.

9. The production method according to claim 1 or 2, wherein ​ The chelating agent (C) contains one or more selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetetraacetic acid, triethylenetetraminehexaacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid, 1-hydroxyethane-1,1-diphosphonic acid, and 2-phosphonobutane-1,2,4-butanetricarboxylic acid.

10. An aqueous surface treatment agent for a metal member obtained by processing / molding and containing an aqueous resin (A), a metal compound (B), a chelating agent (C), and water, wherein The aqueous resin (A) contains one or more selected from the group consisting of an aqueous epoxy resin, an aqueous polyurethane resin, and an aqueous silicone oligomer, The metal compound (B) contains one or more metal elements selected from the group consisting of magnesium, aluminum, titanium, and zirconium, The chelating agent (C) is one or more selected from the group consisting of an alcohol amine, a hydroxyl group-containing organophosphonic acid compound, and a carboxyl group-containing organophosphonic acid compound, The solid content of the aqueous surface treatment agent is in the range of 0.01 to 6 mass% with respect to the total mass of the aqueous surface treatment agent.

11. The aqueous surface treatment agent according to claim 10, wherein The solid content of the aqueous surface treatment agent is in the range of 0.01 to 3 mass% with respect to the total mass of the aqueous surface treatment agent.

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