JP4661627B2 - Surface-treated zinc-based plated metal material and method for producing the same - Google Patents

Description

  The present invention relates to a surface-treated zinc-based plated metal material and a method for producing the same, and particularly to a chromium-free surface-treated zinc-based plated metal material used for automobiles, home appliances, building materials, and the like, and a method for producing the same.

  Surface-treated zinc-based plated metal materials (hereinafter sometimes referred to as “zinc-based plated steel sheets”) widely used in automobiles, home appliances, and building materials have been conventionally treated by chromate treatment in order to improve their corrosion resistance. After a chromate film is formed on the surface, an organic film is formed as necessary, and then commercialized.

  However, since the chromate film contains hexavalent chromium that is harmful to the human body, there are concerns about dangers such as harming the health of people involved in the manufacture of galvanized steel sheets and causing environmental pollution. For this reason, various techniques for obtaining a zinc-based plated steel sheet excellent in corrosion resistance and the like without using a treatment liquid containing chromium have been proposed today.

As an example of such a technique, a technique of forming an appropriate metal oxide layer in place of chromium on the surface of a steel material can be cited. For example, as a technique for forming an oxide layer on the surface of a steel material, Patent Document 1 discloses a technique in which a ZnO-based oxide layer is provided on the surface of a zinc-based plated steel sheet and an inorganic oxide layer is provided thereon. ing. Patent Document 2 discloses a technique for coating the surface of a zinc-based plated steel sheet with a zinc oxide layer. Patent Document 3 discloses that a zinc-based plated steel sheet is electrolytically treated at a current density of 1.0 to 20 A / dm ² or less in an aqueous solution containing 0.01 to 3 mol / L in terms of Mg. A technique for forming a coating containing 5 to 3000 mg / m ² of Mg oxide and / or hydroxide in terms of Mg on the surface of a zinc-based plating is disclosed.
JP-A-7-138764 JP 2000-64054 A JP 2004-18960 A

  However, the technique disclosed in Patent Document 1 has a problem that it is difficult to obtain a steel sheet having corrosion resistance equivalent to or higher than that of a chromate-treated steel sheet. In addition, even the technique disclosed in Patent Document 2 has a problem that it is difficult to obtain a steel sheet having corrosion resistance superior to that of a chromate-treated steel sheet. Furthermore, the technique disclosed in Patent Document 3 has a problem that it is difficult to obtain a steel plate having corrosion resistance and fingerprint resistance superior to those of a chromate-treated steel plate.

  Therefore, the present invention provides a surface-treated zinc-based plating metal material having excellent corrosion resistance, and a surface-treated zinc-based plating capable of producing the surface-treated zinc-based plating metal material without using a chromium-containing treatment liquid. It is an object to provide a method for manufacturing a metal material.

  The present inventors obtained a zinc-based plated steel material by electrolysis using a zinc-based plated steel material as a cathode in an aqueous solution containing zinc ions, aluminum ions, magnesium ions, and nitrate ions in predetermined amounts. It was found that the performance of the surface-treated zinc-based plated metal material was good. Furthermore, the present inventors investigated the surface state of the surface-treated zinc-based plated metal material thus obtained, and also investigated appropriate manufacturing conditions. In addition, the performance of the surface-treated zinc-based plated metal material in which a resin coating was provided on the surface-treated zinc-based plated metal material that had undergone the above electrolysis was investigated. This invention is made | formed based on the said knowledge and investigation.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiments.

  The first aspect of the present invention is a surface-treated zinc-based plated metal material (10) provided with a first coating (2) on a zinc-based plating layer (1), wherein the first coating (2) is: It is mainly composed of a composite oxide of zinc, aluminum and magnesium, and contains zinc in the metallic state. The metallic zinc is on the interface side of the first coating (2) with the zinc-based plating layer (1). The zinc constituting the composite oxide is concentrated on the interface side of the first coating (2) with the zinc-based plating layer (1), and the aluminum constituting the composite oxide is The above-mentioned problem is solved by the surface-treated zinc-based plated metal material (10) characterized by being concentrated on the surface side of the first coating (2).

  Here, as a specific example of the zinc-based plating layer (1) according to the first aspect of the present invention, in addition to the zinc plating layer provided in the electrogalvanized steel material and the hot dip galvanized steel material, Examples thereof include a zinc-based alloy plating layer provided on a hot-dip zinc-based alloy-plated steel material. Specific examples of plating components other than zinc in the zinc-based alloy plating layer of the electrogalvanized alloy-plated steel material include Ni, Fe, Co, Sn, and combinations thereof. Specific examples of plating components other than zinc in the zinc-based alloy plating layer of the hot-dip zinc-based alloy-plated steel material include Al, Fe, Mg, Si, and combinations thereof. In addition, specific examples of the hot-dip galvanized alloy-plated steel material include a molten 55% Al-zinc alloy-plated steel material and an alloyed hot-dip galvanized steel material. Furthermore, the “surface of the first coating (2)” means the surface of the surface-treated zinc-based plating metal material (10) on the first coating (2) side.

  The second present invention is a surface-treated zinc-based plating comprising a first coating (2) on a zinc-based plating layer (1) and a resin coating (3) on the first coating (2). It is a metal material (20), and the first coating (2) is mainly composed of a composite oxide of zinc, aluminum and magnesium and contains metallic zinc. The coating (2) is concentrated on the interface side with the zinc-based plating layer (1), and the zinc constituting the composite oxide is the same as the zinc-based plating layer (1) of the first coating (2). The surface-treated zinc is characterized in that the aluminum constituting the composite oxide is concentrated on the interface side between the first coating (1) and the resin coating (3). The above-mentioned problem is solved by the system plating metal material (20).

  Here, as a specific example of the zinc-based plating layer (1) according to the second aspect of the present invention, the same zinc-based plating layer according to the first aspect of the present invention can be exemplified. Furthermore, specific examples of the resin film (3) according to the second invention include a urethane resin film, an acrylic resin film, a thermosetting epoxy resin film, and the like.

  In the first or second aspect of the invention, the thickness of the first coating is preferably 50 nm or more and 500 nm or less.

  3rd this invention is 0.05 mol / L or more and 0.15 mol / L or less zinc ion, 0.05 mol / L or more and 0.30 mol / L or less aluminum ion, and 0.05 mol / L or more and 0.15 mol / L or less. / L or less magnesium ions and 0.05 mol / L or more and 0.30 mol / L or less nitrate ions, and in an aqueous solution having a pH of 1.0 to 4.0, a zinc-based plated metal material Is used as a cathode to form a first coating (2) mainly composed of a composite oxide of zinc, aluminum and magnesium and containing zinc in a metallic state on the zinc-based plated metal material. An electrolysis process (hereinafter, also referred to as “electrolysis process”), characterized in that the above problem is achieved by a method for producing a surface-treated zinc-based plated metal material (10). Resolve.

  Here, the zinc-based plated metal material according to the third aspect of the present invention is not particularly limited as long as it is a metal material that has been conventionally subjected to chromate treatment. In addition to zinc-based plated steel materials such as hot-dip galvanized steel materials, zinc-based alloy-plated steel materials such as electrogalvanized alloy-plated steel materials and hot-dip zinc-based alloy plated steel materials.

  4th this invention is 0.05 mol / L or more and 0.15 mol / L or less zinc ion, 0.05 mol / L or more and 0.30 mol / L or less aluminum ion, and 0.05 mol / L or more and 0.15 mol / L or less. / L or less magnesium ions and 0.05 mol / L or more and 0.30 mol / L or less nitrate ions, and in an aqueous solution having a pH of 1.0 to 4.0, a zinc-based plated metal material Is used as a cathode to form a first coating (2) mainly composed of a composite oxide of zinc, aluminum and magnesium and containing zinc in a metallic state on the zinc-based plated metal material. A surface-treated zinc-based plated metal comprising: an electrolysis process; and a resin film formation process in which a resin film (3) is provided on the first film (2) after the electrolysis process. The production method of (20), to solve the above problems.

  Here, the specific example of the zinc-based plated metal material according to the fourth aspect of the present invention is not particularly limited as long as it is a metal material that has been conventionally subjected to chromate treatment. The same thing as the zinc plating metal material concerning 3 of this invention can be mentioned. Furthermore, specific examples of the resin coating according to the present invention include a urethane resin coating, an acrylic resin coating, a thermosetting epoxy resin coating, and the like.

  According to the first aspect of the present invention, the first coating containing the composite oxide of zinc, aluminum, and magnesium and zinc in a metallic state is provided on the zinc-based plating layer, so that it is excellent. A surface-treated zinc-based plated metal material having excellent fingerprint resistance in addition to corrosion resistance can be provided.

  According to the second aspect of the present invention, since the resin film is provided on the first film, the fingerprint resistance of the surface-treated zinc-based plated metal material can be further improved.

  In the first or second aspect of the present invention, if the thickness of the first film is 50 nm or more and 500 nm or less, it is possible to suppress a decrease in electrical conductivity while improving corrosion resistance and fingerprint resistance. A surface-treated zinc-based plated metal material can be provided.

  According to the third aspect of the present invention, the first coating can be formed on the surface of the zinc-based plated metal material by the electrolysis process. Therefore, it is possible to provide a method for producing a surface-treated zinc-based plated metal material having excellent fingerprint resistance in addition to excellent corrosion resistance.

  According to the fourth aspect of the present invention, the resin film can be formed on the first film by the resin film forming step after the electrolysis step. Therefore, a method for producing a surface-treated zinc-based plated metal material having excellent corrosion resistance and fingerprint resistance can be provided.

  Embodiments of the present invention will be described below. In addition, embodiment shown below is an illustration and this invention is not limited to the following embodiment.

1. 1A is a cross-sectional view of the surface-treated zinc-based plated metal material of the present invention according to the first embodiment, and FIG. 1A is a surface-treated zinc-based plated metal material of the present invention according to the second embodiment. Are respectively schematically shown in FIG.

  As shown in FIG. 1 (a), a surface-treated zinc-based plated metal material 10 according to the first embodiment of the present invention includes a zinc-based plated layer 1 formed by plating a base metal material 5, A first coating 2 formed by subjecting the metal material 6 on which the zinc-based plating layer 1 is formed to an electrolytic treatment described later. On the other hand, as shown in FIG. 1B, the surface-treated zinc-based plated metal material 20 of the present invention according to the second embodiment is formed by subjecting the base metal material 5 to a plating process. A layer 1, a first coating 2 formed by subjecting the metal material 6 on which the zinc-based plating layer 1 is formed to an electrolytic treatment described later, and a resin coating 3 provided on the first coating 2. And.

  Specific examples of the metal material 6 according to the present invention include electrogalvanized steel, electrogalvanized alloy-plated steel, hot-dip galvanized steel, hot-dip galvanized steel. Specific examples of plating components other than zinc in the electrozinc alloy-plated steel material include Ni, Fe, Co, Sn, and combinations thereof. In addition, specific examples of plating components other than zinc in the hot dip zinc-based alloy plated steel material include Al, Fe, Mg, Si, and combinations thereof. Further, when a hot dip galvanized steel sheet is used as the metal material 6 according to the present invention, as a specific example of the hot dip galvanized steel sheet, a molten 55% Al-zinc alloy galvanized steel material, galvannealed galvanized steel A steel material etc. can be mentioned. In addition, the shape of the surface-treated zinc-based plated metal materials 10 and 20 according to the present invention is not particularly limited, and may be a plate shape or a belt shape, or other shapes. However, in the electrolysis step included in the production method of the present invention, from the viewpoint of facilitating electrolysis using a current having a high current density and facilitating continuous production of a metal material, It is preferable to do.

  The first coating 2 and the resin coating 3 provided on the surface-treated zinc-based plated metal materials 10 and 20 according to the present invention will be described below.

1.1. First coating 2
The first coating 2 according to the present invention is mainly composed of a composite oxide of zinc, aluminum, and magnesium, and further includes metallic zinc. This metallic zinc is concentrated on the interface side of the first coating 2 with the zinc-based plating layer 1. By adopting a configuration in which the first coating 2 is provided with metallic zinc, the electrolysis reaction proceeds even at a relatively high current density (for example, 20 A / dm ² or more), and a uniform first It is considered that the film 2 can be formed. In addition, zinc constituting the composite oxide is concentrated on the interface side of the first coating 2 with the zinc-based plating layer 1, while aluminum constituting the composite oxide is concentrated on the first coating 2. 2 is concentrated on the surface side. The surface-treated zinc-based plated metal materials 10 and 20 including the first coating 2 having such a structure exhibit excellent corrosion resistance as will be described later. Further, the surface-treated zinc-based plated metal materials 10 and 20 according to the present invention have excellent fingerprint resistance even when the resin coating 3 is not formed on the first coating 2.

  In the present invention, if the thickness of the first coating 2 is too thin, the corrosion resistance becomes disadvantageous. When the resin film 3 is not provided on the first film 2, the thickness is preferably 150 nm or more. On the other hand, if the first coating 2 is too thick, the adhesion between the zinc-based plating layer 1 and the first coating 2 may be decreased, and the electrical conductivity of the surface-treated zinc-based plating metal materials 10 and 20 is decreased. Therefore, when the resin coating 3 is not provided on the first coating 2, the thickness is preferably 500 nm or less. Preferably, it is 400 nm or less. When the resin coating 3 is provided, the thickness of the first coating 2 is preferably 150 nm or more and 350 nm or less.

1.2. Resin coating 3
The resin coating 3 can be provided on the first coating 2 as necessary when higher performance is required for corrosion resistance, fingerprint resistance, slidability, and the like. Hereinafter, preferred embodiments according to some applications will be described.

  Since the surface-treated steel sheet for housing of home appliances is usually required to have almost no white rust after the test for 72 to 120 hours in a salt spray test, for example, as corrosion resistance, the surface treatment according to the present invention. When the zinc-based plated metal material 20 is used as the surface-treated steel sheet, it is preferable to provide the resin film 3 having a thickness of about 0.5 to 2 μm on the first film 2. When suppression of abrasion (darkening due to rubbing between steel plates) is strongly required, it is preferable to use urethane resin or acrylic resin as the resin, and depending on the formability required for the surface treated steel plate A solid lubricant such as wax may be contained in the organic coating.

  On the other hand, when the surface-treated zinc-based plated metal material 20 according to the present invention is used as a surface-treated steel sheet for a fuel tank for automobiles, as a preferable resin film provided on the surface corresponding to the tank inner surface, a thermosetting urethane-based material is used. Examples thereof include a resin film and a thermosetting epoxy resin film.

  The surface-treated zinc-based plated metal material 20 according to the second embodiment is, for example, a conventional ordinary chromate as in the examples described later in applications such as housings for home appliances or fuel tanks for automobiles. Shows the same or better performance than the treated product.

2. Manufacturing method of surface-treated zinc-based plated metal material Prior to describing the manufacturing method of the surface-treated zinc-based plated metal material of the present invention, first, regarding the mechanism assumed as an electrolysis reaction for forming the first coating 2 explain.

2.1. Film Formation Mechanism In an acidic aqueous solution containing zinc ions, when electrolysis is performed using a metal material as a cathode, metal zinc is deposited based on the reaction according to the following reaction formula (1).
Zn ²⁺ + 2e ⁻ → Zn (1)

Here, when nitrate ions coexist in the aqueous solution, a reaction according to the following reaction formula (2) occurs simultaneously, and an interface where metal zinc Zn is about to precipitate by hydroxide ions generated by the reaction. The pH of the water increases greatly.
NO ₃ ⁻ + H ₂ O + 2e ⁻ → NO ₂ ⁻ + 2OH ⁻ (2)

As a result, when nitrate ions coexist in an acidic aqueous solution containing zinc ions, the formation reaction of zinc oxide (or zinc hydroxide before dehydration) according to the following reaction formula (3) is likely to occur.
Zn ²⁺ + 2OH ⁻ → Zn (OH) ₂ (→ ZnO + H ₂ O) (3)

  Here, when aluminum ions and magnesium ions are further contained in the aqueous solution containing zinc ions and nitrate ions, aluminum is formed when zinc oxide is formed on the surface of the metal material by the reaction of the above reaction formula (3). And magnesium is incorporated in the oxide state. Thereby, it is considered that the first coating 2 mainly composed of a composite oxide of zinc, aluminum, and magnesium is formed on the surface of the metal material.

  In addition, at the initial stage of electrolysis (hereinafter sometimes referred to as “electrolysis”), the metal zinc precipitation reaction of the above reaction formula (1) and the oxide formation reaction according to the above reaction formulas (2) and (3). Are considered to occur simultaneously, and it is considered that the reactions according to the reaction formulas (2) and (3) become dominant as the electrolysis progresses. As a result, it is considered that the first coating 2 is formed in such a manner that zinc in the metal state is concentrated on the interface side with the zinc-based plating layer 1 and Al in the oxide state is concentrated on the surface side.

2.2. Aqueous Solution An aqueous solution (hereinafter referred to as “electrolytic solution”) used in the electrolysis process for forming the first coating 2 will be described.
The electrolytic solution contains zinc ions, aluminum ions, magnesium ions and nitrate ions. When the zinc ion concentration in the electrolytic solution is too low, supply of zinc ions to the interface between the electrolytic solution and the metal material 6 is insufficient, and the first coating 2 is hardly formed on the surface of the metal material 6. When the zinc ion concentration is too high, the metal zinc precipitation reaction according to the reaction formula (1) becomes dominant, so that the first coating 2 is hardly formed on the surface of the metal material 6. Therefore, from the viewpoint of obtaining the surface-treated metal materials 10 and 20 having excellent corrosion resistance by appropriately forming the first coating 2 on the surface of the metal material 6, the zinc ion concentration in the electrolytic solution according to the present invention is 0.05 mol / L or more. From the same viewpoint, the zinc ion concentration is set to 0.15 mol / L or less. More preferably, it is 0.08 mol / L or more and 0.12 mol / L or less.

  If the concentration of aluminum ions in the electrolytic solution is too low, the surface-treated zinc-based plated metal materials 10 and 20 having a beautiful lightness cannot be obtained. Therefore, the concentration is set to 0.05 mol / L or more. Preferably it is 0.08 mol / L or more. On the other hand, if the concentration is too high, the corrosion resistance of the surface-treated zinc-based plated metal material 10 obtained is lowered, so that it is 0.30 mol / L or less. Preferably it is 0.12 mol / L or less.

  The concentration of magnesium ions in the electrolytic solution is set to 0.05 mol / L or more from the viewpoint of setting the surface-treated zinc-based plated metal materials 10 and 20 having good corrosion resistance. Preferably it is 0.08 mol / L or more. On the other hand, if the concentration is too high, it is disadvantageous in terms of cost, so 0.15 mol / L or less. Preferably it is 0.12 mol / L or less.

  The nitrate ions in the electrolytic solution increase the pH of the electrolytic solution in the vicinity of the surface of the metal material 6 by the reaction (2), and easily cause an oxide formation reaction by the reaction (3). If the nitrate ion concentration is too low, it is considered that the pH increase due to the reaction (2) is insufficient, so 0.05 mol / L or more is set. Preferably it is 0.08 mol / L or more. On the other hand, the concentration of nitrate ions contained in the electrolyte is 0.30 mol / L or less in order to prevent the pH from increasing more than necessary and preventing metal precipitation. Preferably it is 0.12 mol / L or less.

  The pH of the electrolytic solution according to the present invention is set to 1.0 or more in order to increase the pH to a level necessary and sufficient for the oxide to precipitate. Preferably it is 2.0 or more. On the other hand, in order to prevent a situation where the pH rises more than necessary and no metal deposition occurs, the pH is set to 4.0 or less. Preferably it is 3.0 or less.

  Such an electrolyte uses, for example, zinc, aluminum, magnesium nitrate, sulfate, carbonate, etc., and metal zinc, aluminum, magnesium, etc., so that each ion concentration and pH are within the above range. It can be obtained by blending. As shown in the examples below, the electrolyte solution formulated using zinc, aluminum, magnesium nitrate and sulfate has a pH in the range of approximately 2.0 to 3.0, and the buffering action of magnesium sulfate. Therefore, even if it is manufactured (electrolyzed) for a long time, it has an advantage that it is possible to suppress fluctuations in pH. The pH of the electrolytic solution may be adjusted by adding other appropriate acid or alkali such as sulfuric acid or sodium hydroxide. In addition, the replenishment of the electrolyte solution during long-time production can also be supplied in the form of the salt or metal.

  Furthermore, in the present invention, the temperature of the electrolytic solution is preferably set to 40 ° C. or higher from the viewpoint of easily allowing the electrolysis reaction to proceed. Moreover, it is preferable that the temperature of electrolyte solution shall be 80 degrees C or less from a viewpoint of preventing evaporation of electrolyte solution. Moreover, it is preferable to set it as the temperature range of 40 degreeC or more and 80 degrees C or less also from a viewpoint that it is easy to stabilize temperature practically.

  In addition to the above-mentioned ions, the electrolytic solution according to the present invention may contain other components as long as the corrosion resistance of the surface-treated zinc-based plated metal materials 10 and 20 obtained by the present invention is not adversely affected. good. Specific examples of other components include sulfate ions and carbonate ions, and further, for example, components that are considered to be mixed due to the components of the metal material 6 (for example, the metal material 6 is a steel material or a plating material). In some cases, Fe, Ni, etc.), components added for other purposes (eg, oxide fine particles such as V, Zr, Ti, Si, and ions containing these metal elements) can be mentioned. . In addition, since this invention makes it one of the objectives to obtain the surface treatment zinc-type plating metal materials 10 and 20 which have the outstanding corrosion resistance using the processing liquid which does not contain the substance which has a bad influence on environment, such as chromium, It is preferable that chromium is not contained as much as possible in the electrolytic solution, and it is preferable that lead, cadmium, mercury and the like are not contained as much as possible.

2.3. Conditions for electrolysis The type of electric current that can be used when performing electrolysis according to the present invention is not particularly limited. Examples of the current that can be used include a direct current and a pulse current. Here, when electrolysis according to the present invention is performed using a direct current, the current density is 0.1 A / dm ² from the viewpoint of uniformly forming the first coating 2 on the surface of the metal material 6. The following is preferable.

On the other hand, by performing electrolysis using a pulse current, even when electrolysis is performed using a current having a high current density such as 20 A / dm ² or more, the first containing magnesium ions, aluminum ions, and the like The coating 2 can be uniformly formed on the surface of the metal material 6. Here, from the viewpoint of uniformly forming the first coating 2 on the surface of the metal material 6, the frequency of the pulse waveform in the pulse current is preferably 0.1 Hz or more. Further, from the viewpoint of forming a dense first coating 2 effective for corrosion resistance, the frequency is preferably 0.6 Hz or less. Furthermore, the duty ratio of the pulse waveform is preferably 0.5 or less from the viewpoint of providing an electrolytic OFF time necessary for supplying consumed ions.

In addition, from the viewpoint of forming the first coating 2 having a thickness capable of improving the corrosion resistance on the surface of the metal material 6, the energization amount when performing the electrolysis according to the present invention is 10 C / dm ² or more. Preferably there is. On the other hand, from the viewpoint of obtaining the surface-treated zinc-based plated metal materials 10 and 20 having excellent corrosion resistance by forming the first coating 2 having good adhesion on the surface of the metal material 6, the energization amount is 500 C / It is preferably dm ² or less. More preferred energization amount is 100~300C / dm ^2.

When electrolysis is performed using an electrolytic solution that satisfies the above conditions, the amount of current applied should be 500 C / dm ² when electrolyzing with a flow cell, which will be described later, depending on the flow conditions of the electrolytic solution and other electrolytic conditions. Thus, when electrolysis is performed on the surface of the metal material 6 with a beaker cell of about 400 nm, the first coating 2 having a large thickness but a maximum thickness of 500 nm is formed. However, in either case, if the energization amount is too large, the adhesion between the galvanized layer 1 and the first coating layer 2 may be reduced, so that the energization amount is 500 C / dm ² or less as described above. It is preferable to do this. Although there is a problem of variation, electrolysis in a beaker cell is superior from the viewpoint of electrolysis efficiency than electrolysis under a high flow condition using a flow cell.

2.3. Other Manufacturing Methods As an example of a preferable manufacturing method when the first coating is provided on the electrogalvanized steel strip, in the continuous electroplating line of the steel strip, the steel strip is applied to the steel strip in the upstream electrolytic bath (plating bath). After forming a zinc-type plating layer, the method etc. which form a 1st film on the said zinc-type plating layer in the electrolytic bath (plating tank) of a downstream side continuously can be mentioned. In the case where a resin film is further formed on the first film, the resin film may be formed by washing with water and drying after the first film is formed, and then forming the resin film on the first film. In addition, the manufacturing method which the manufacturing method of the surface treatment zinc-based plating metal material concerning this invention can take is not limited to this. Zinc-based plating, first film formation (electrolysis), and resin film formation need not be performed in one line and equipment, and the plating process, the first film formation process, and the resin film formation process are different from each other. It may be a form performed in

3. Applications Some examples of preferable applications of the surface-treated zinc-based plated metal materials 10 and 20 according to the present invention are illustrated below.
Since the surface-treated zinc-based plated metal material 10 according to the first embodiment of the present invention has a feature that the phosphate treatment property is good, for example, phosphoric acid as a paint base treatment for automobile bodies, parts, home appliances, etc. It can be used in applications where salt treatment is applied. It is considered that the surface-treated zinc-based plated metal material 10 according to the first embodiment is excellent in phosphate treatment because the first coating 2 is relatively easily dissolved in the phosphate treatment solution. It is done.

  On the other hand, the surface-treated zinc-based plated metal material 20 according to the second embodiment of the present invention can be used for household appliances as described above. In addition, the 1st film | membrane 2 concerning this invention itself has a small discoloration by fingerprint adhesion. Therefore, depending on the level of corrosion resistance required, the surface-treated zinc-based plated metal material 10 of the present invention according to the first embodiment can also be applied to home appliances and the like, for example, applied to motor cases and the like. It is also possible. Moreover, since the surface-treated zinc-based plated metal material 20 according to the second embodiment of the present invention has a feature that it is excellent in corrosion resistance in deteriorated gasoline, it is useful as a fuel tank material for automobiles, for example.

<Example 1>
1) Production of surface-treated zinc-based plated metal material according to the first embodiment An electrolysis apparatus (hereinafter referred to as “flow cell”) capable of flowing an electrolytic solution using an electrogalvanized steel sheet having a plating adhesion of 20 g / m ² as a cathode (Hereinafter, this material is referred to as “electrolytically treated product” in the examples of the present invention). In addition, the magnitude | size of the electricity supply surface of the electrogalvanized steel plate used as the cathode of electrolysis was 100 mm x 100 mm. A top view and a side view of the flow cell are shown in FIGS. 2 (a) and 2 (b). In FIG. 2, the electrolytic solution 53 in the electrolytic cell 50 is given a flow by a pump 54, and the cathode 51 and the anode 52 are connected to a pulse power supply 55. Note that the arrows in FIGS. 2A and 2B indicate the flow direction of the electrolytic solution 53.
In this example, an aqueous solution containing 30 g / L of zinc nitrate hexahydrate, 15 g / L of aluminum sulfate 12 hydrate, and 25 g / L of magnesium sulfate heptahydrate was used as the electrolyte. The temperature of the electrolytic solution was 60 ° C., and the pH was 2.5. Here, the zinc ion concentration in the electrolytic solution was 0.06 mol / L, the aluminum ion concentration was 0.05 mol / L, the magnesium ion concentration was 0.11 mol / L, and the nitrate ion concentration was 0.12 mol / L.
Further, the flow rate of the electrolyte solution between the cathode and the anode is 0.5 m / s, and for electrolysis, the frequency is 0.2 Hz, the duty ratio is 0.2, and the current density during energization is 10 A / dm ² . A pulse current was used, and the energization amount was 192 C / dm ² .

2) Analysis of a film The SEM image which observed the surface vicinity cross section of the surface treatment zinc-plated steel plate obtained in this way with the scanning electron microscope (SEM) is shown in FIG. In FIG. 3, the thickness of the first coating 32 formed on the zinc-based plating layer 31 is slightly over 200 nm (for example, about 260 nm).
Next, from the surface of the surface-treated zinc-based plated steel sheet shown in FIG. 3, the depth of the steel sheet is analyzed by sputtering with Ar using an X-ray photoelectron spectrometer (XPS). Directional elemental analysis was performed. The results of elemental analysis are shown in FIG. 4, and details of elemental analysis conditions are shown below.

(XPS elemental analysis measurement conditions)
Light source: Monochromatic Al-Kα ray (1486.6 eV)
X-ray beam diameter: 100 μm × 100 μm
X-ray incident direction: 45 ° with respect to the normal direction of the sample surface
Photoelectron capture direction: 45 ° to the normal direction of the sample surface
Measurement method: Measure XPS spectrum while scraping the surface by Ar sputtering Ar sputtering area: 1 mm x 1 mm
Ar ion incident direction: Normal direction of sample surface Depth from surface: Sputtering speed is measured by SiO ₂ / Si with known film thickness, and sputtering time is converted to depth from surface State analysis method:
Zn / ZnO = Zn-LMM Auger peak (binding energy; around 498 eV)
・ AlO = Al-2p peak (binding energy; around 74 eV)
MgO = Mg-KLL Auger peak (binding energy; around 305 eV)
O = O-1s peak (binding energy: 531 eV)
The existence ratio is calculated from the intensity ratio of each peak to the total area intensity of these peaks.

As shown in FIG. 4, an oxide film (first film 32) having a thickness of 200 nm or more was detected on the zinc-based plating layer 31 by XPS elemental analysis measurement. From the first coating 32, spectra of zinc in the oxide state, aluminum, magnesium, and zinc in the metal state were detected. Further, in the vicinity of the interface between the first coating 32 and the zinc-based plating layer 31, zinc in the metal state and zinc in the oxide state are concentrated, and aluminum in the oxide state is concentrated on the surface side of the first coating 32. It was converted. Although determination of each element is difficult, it is estimated from FIG. 4 that, for example, magnesium in an oxide state provided in the first coating 32 is 5 mg / m ² or less.

3) Performance investigation Chromate treatment material of surface-treated zinc-based plated steel sheet and electrogalvanized steel sheet obtained under the above conditions (plated product amount of 20 g / m ² and chromium deposit amount of 20 mg / m ² . In the examples, the following various performance investigations were performed on “chromate products”), and the performances were compared.

a) Corrosion resistance The back surface and the end of the test material subjected to an overhanging process in which the Erichsen value stipulated in JIS B7729 “Eriksen Test Machine” is 6 mm are sealed with polyester tape to obtain a test material. . Thereafter, a salt spray test was performed on the surface of the test material over 24 hours, and the occurrence of white rust on the surface of the test material was observed. Corrosion resistance evaluation was performed based on the following criteria. Table 1 shows the evaluation results of the corrosion resistance.
Evaluation;
◎: No white rust occurrence ○: Ratio of white rust occurrence area in the evaluation surface is less than 5% △: Ratio of white rust occurrence area in the evaluation surface is 5% or more and less than 20% ×: White rust generation in the evaluation surface Area ratio is 20% or more

b) Sliding property The friction coefficient was measured by the pin-on-disk test method described in Japanese Patent Application Laid-Open No. 2003-136151 under the following conditions with rust preventive oil applied to the treated surface. Table 1 shows the measured friction coefficient values. In general, it can be determined that a member having a smaller friction coefficient has superior slidability.
Test conditions;
Load: 29.4N, Slider material: SKD steel,
Slider shape: φ5 spherical surface, test temperature: 60 ° C,
Rotating radius: 10mm, sliding speed: 1rpm
Test rotation speed: 20 times
Friction coefficient: An average value is calculated from 12 measured values per rotation, and is the maximum of 20 times.

c) Conductivity On the cold-rolled steel sheet, an electrolytically treated product and a chromate product treated on both sides are respectively arranged so that the length of the overlapping portion with the cold-rolled steel plate is 50 mm, and further the test material A graphite measuring element having a diameter of 0.9 mm was pressed onto the substrate with a load of 2.94 N. And the resistance between a graphite measuring element and a cold-rolled steel plate was measured with the contact electric resistance meter ML-500 (made by Yamazaki Corp.). Table 1 shows the measurement results of conductivity.

d) Fingerprint resistance After applying petrolatum to the electrolyzed product and chromate product, the petrolatum was wiped off with Kimwipe. And the color difference (color difference (DELTA) E in a Hunter Lab color system) before and after petrolatum application was measured using Suga Test Instruments color difference meter SM-7-IS-2B. The results are shown in Table 1. In general, a member having a smaller color difference ΔE can be determined to have better fingerprint resistance, and the value of the color difference ΔE is preferably 3 or less.

表１より、本発明の表面処理亜鉛系めっき金属材は、従来のクロメート処理材よりも、優れた耐食性、摺動性、導電性、及び耐指紋性を有していることが確認された。

From Table 1, it was confirmed that the surface-treated zinc-based plated metal material of the present invention has superior corrosion resistance, slidability, conductivity, and fingerprint resistance than conventional chromate treatment materials.

<Example 2>
1) Production of surface-treated zinc-based plated metal material according to the first embodiment Electrolysis was performed using a flow cell with an electrogalvanized steel sheet having a plating adhesion amount of 20 g / m ² as a cathode. In addition, the magnitude | size of the electricity supply surface of the electrogalvanized steel plate used as the cathode of electrolysis was 100 mm x 100 mm.
In this example, magnesium sulfate hexahydrate was added to an aqueous solution containing 30 g / L of zinc nitrate hexahydrate and 50 g / L of aluminum sulfate 12 hydrate (hereinafter referred to as “Al sulfate”). An aqueous solution appropriately added (hereinafter referred to as “Mg sulfate”) was used as the electrolytic solution. The temperature of the electrolytic solution was 60 ° C., and the pH was 2.5. Here, the zinc ion concentration in the electrolyte before addition of Mg sulfate was 0.06 mol / L, and the aluminum ion concentration was 0.18 mol / L. Moreover, the relationship that the magnesium ion density | concentration in the said electrolyte solution increases 0.004 mol / L when Mg sulfate 1g / L is added to the said electrolyte solution is recognized.
Further, the flow rate of the electrolyte solution between the cathode and the anode is 0.5 m / s, and for electrolysis, the frequency is 0.2 Hz, the duty ratio is 0.2, and the current density during energization is 40 A / dm ² . A pulse current was used, and the energization amount was 192 C / dm ² .

2) Salt spray test After the back and end surfaces of the test material obtained under the above conditions are sealed with polyester tape to obtain a test material, the surface of the test material is defined in JIS Z2371 “Salt spray test method”. The salt spray test was performed over 24 hours, and the corrosion resistance of the test material was evaluated based on the corrosion weight loss of the test material after the test. FIG. 5 shows the relationship between the SST corrosion weight loss and the Mg sulfate addition amount when Mg sulfate was added to an aqueous solution containing zinc nitrate hexahydrate 30 g / L and 50 g / L Al sulfate. In addition, the chromate processing material (commercial item, plating adhesion amount 20 g / m ² , chromium adhesion amount 20 mg / m ² ) of the electrogalvanized steel sheet was used as a comparative material. Corrosion weight loss of the comparative material is shown by a broken line in FIG.

  From FIG. 5, when Mg sulfate is added to a zinc nitrate aqueous solution containing Al sulfate and magnesium ions are added to an aqueous solution containing zinc ions, aluminum ions, and nitrate ions, the SST corrosion weight loss is higher than that of the chromate treatment material. Significantly reduced. Therefore, it was confirmed that the surface-treated zinc-based plated metal material of the present invention has better corrosion resistance than the chromate-treated material.

<Example 3>
1) Production of surface-treated zinc-based plated metal material according to the second embodiment After electrolytic treatment of the electrogalvanized steel sheet under the same conditions as in Example 1, a urethane-based clear resin emulsion is further formed on the first film. By applying a liquid (containing 30% silica and 10% polyethylene wax with respect to the solid resin content), a resin film having a thickness of 1.5 μm is formed, and the surface treatment according to the second embodiment A zinc-based plated metal material (hereinafter referred to as “second electrolytically treated product”) was produced. And the chromate goods were produced by forming the said resin film in the test material which performed the chromate process (Cr adhesion amount: 10 mg / m < ² >).

2) Performance evaluation About the 2nd electrolytically processed product (Example) and chromate product (comparative example) obtained by the said procedure, corrosion resistance, sliding property, electroconductivity, and fingerprint resistance were evaluated. Here, the evaluation methods of slidability, conductivity, and fingerprint resistance were the same as in Example 1. On the other hand, the corrosion resistance is the same as the salt spray test in Example 2 except that the surface of the second electrolytically treated product and chromate product is cross-cut and sprayed with salt water for 240 hours. The evaluation was made by comparing the second electrolytically treated product that had undergone the above and the chromate product. In FIG. 6, the external appearance photograph of the 2nd electrolytic treatment goods and chromate goods after a salt spray test is shown. FIG. 7 shows the slidability evaluation result of the second electrolytic treatment product and chromate product, FIG. 8 shows the conductivity evaluation result of the second electrolytic treatment product and chromate product, and FIG. The fingerprint resistance evaluation results of the electrolytically treated product and the chromate product are shown respectively.

  From FIG. 6, the second electrolytically treated product (Example) had white rust from the cut portion, whereas the comparative chromate product (Comparative Example) had red rust. That is, it was confirmed that the surface-treated zinc-based plated metal material according to the present invention has better corrosion resistance than the chromate product. 7 to 9, the surface-treated zinc-based plated metal material (Example) according to the present invention has slidability, conductivity, and fingerprint resistance equal to or higher than those of the chromate product (Comparative Example). It was confirmed.

<Example 4>
1) Preparation of surface-treated zinc-based plated metal material according to second embodiment After electrolytic treatment of an electrogalvanized steel sheet under the same conditions as in Example 1, a urethane-based clear resin emulsion liquid ( A resin film having a thickness of 1.5 μm was formed by applying 30% silica and 10% polyethylene wax) to the resin solid content, thereby producing a third electrolytically treated product. As a comparative material, a test material (chromate product) was prepared by subjecting an electrogalvanized steel sheet to chromate treatment (Cr adhesion amount: 50 mg / m ² ).

2) Performance evaluation The third electrolytically treated product (Example) and chromate product (Comparative Example) obtained by the above procedure were cups with a diameter of 50 mm and a depth of 25 mm so that the resin coating surface (clear surface) was the inner surface. Formed into a shape. Further, a deteriorated gasoline simulation liquid (a mixture of 3 ml of a 300 ppm formic acid aqueous solution and 27 ml of gasoline) was sealed and sealed in a room kept at 45 ° C. FIG. 10 shows the corrosion state of the third electrolytically treated product (Example) and the chromate product (Comparative Example) after standing for 720 hours. From FIG. 10, the electrolytically treated product (Example) produced less red rust than the chromate product (Comparative Example). Therefore, it was confirmed by this corrosion test that the surface-treated zinc-based plated metal material according to the present invention has corrosion resistance equivalent to or higher than that of chromate even in deteriorated gasoline.

It is sectional drawing which shows roughly the surface treatment zinc-based plating metal material of this invention. It is the upper side figure and side view of a flow cell. It is a figure which shows the SEM observation result of the surface vicinity cross section of a surface treatment galvanized steel plate. It is a figure which shows the XPS cross-section analysis result of a surface treatment zinc-plated steel plate. It is a figure which shows the relationship between the sulfuric acid Mg addition amount and SST corrosion weight loss by a salt spray test. It is a figure which shows the external appearance of the electrolytic treatment goods and chromate goods after a salt spray test. It is a figure which shows the slidability evaluation result of an electrolytic treatment goods and a chromate goods. It is a figure which shows the electroconductivity evaluation result of an electrolytic treatment product and a chromate product. It is a figure which shows the anti-fingerprint property evaluation result of an electrolytic treatment product and a chromate product. It is a figure which shows the corrosion state of an electrolytic treatment goods and a chromate goods.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Zinc type plating layer 2 1st film 3 Resin film 6 Metal material 10, 20 Surface treatment zinc type plating metal material 53 Electrolyte solution (aqueous solution)

Claims (5)

A surface-treated zinc-based plating metal material comprising a first coating on a zinc-based plating layer,
The first film is mainly composed of a composite oxide of zinc, aluminum, and magnesium, and contains zinc in a metallic state.
The zinc in the metallic state is concentrated on the interface side with the zinc-based plating layer of the first coating,
Zinc constituting the composite oxide is concentrated on the interface side with the zinc-based plating layer of the first coating,
A surface-treated zinc-based plated metal material, wherein the aluminum constituting the composite oxide is concentrated on the surface side of the first coating. A surface-treated zinc-based plating metal material comprising a first coating on a zinc-based plating layer and a resin coating on the first coating,
The first film is mainly composed of a composite oxide of zinc, aluminum, and magnesium, and contains zinc in a metallic state.
The zinc in the metallic state is concentrated on the interface side with the zinc-based plating layer of the first coating,
Zinc constituting the composite oxide is concentrated on the interface side with the zinc-based plating layer of the first coating,
A surface-treated zinc-based plated metal material, wherein the aluminum constituting the composite oxide is concentrated on the interface side of the first coating with the resin coating. 3. The surface-treated zinc-based plated metal material according to claim 1, wherein the first coating has a thickness of 50 nm to 500 nm. 0.05 mol / L or more and 0.15 mol / L or less zinc ion, 0.05 mol / L or more and 0.30 mol / L or less aluminum ion, 0.05 mol / L or more and 0.15 mol / L or less magnesium ion, And electrolysis using a zinc-based plated metal material as a cathode in an aqueous solution containing 0.05 mol / L or more and 0.30 mol / L or less of nitrate ions and having a pH of 1.0 to 4.0. The zinc-based plated metal material is provided with an electrolysis step of forming a first coating mainly containing a composite oxide of zinc, aluminum and magnesium and containing zinc in a metallic state. A method for producing a surface-treated zinc-based plated metal material. 0.05 mol / L or more and 0.15 mol / L or less zinc ion, 0.05 mol / L or more and 0.30 mol / L or less aluminum ion, 0.05 mol / L or more and 0.15 mol / L or less magnesium ion, And electrolysis using a zinc-based plated metal material as a cathode in an aqueous solution containing 0.05 mol / L or more and 0.30 mol / L or less of nitrate ions and having a pH of 1.0 to 4.0. An electrolysis step of forming a first coating on the zinc-based plating metal material, the main component being a composite oxide of zinc, aluminum, and magnesium and containing zinc in a metallic state;
A resin film forming step of providing a resin film on the first film after the electrolysis step;
A method for producing a surface-treated zinc-based plated metal material, comprising:

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