JP4103861B2 - Blackened steel sheet and manufacturing method thereof - Google Patents

Description

  The present invention relates to a blackened steel plate suitably used for home appliances and the like and a method for producing the same, and more particularly to a chromium-free blackened steel plate and a method for producing the same.

  Blackened steel sheets are widely used as materials for various devices, mainly home appliances such as personal computers, copiers, audio equipment, and air conditioners, because they are excellent in corrosion resistance and decorativeness. In producing such a blackened steel sheet, a method of forming a chromate film by chromate treatment after forming a blackened steel sheet that has been conventionally zinc-plated, and then forming a resin film as necessary. It has been used a lot.

  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 blackened steel sheets and causing environmental pollution. For this reason, various techniques for obtaining a blackened steel sheet excellent in corrosion resistance and decorativeness without using a treatment liquid containing chromium have been proposed today.

  For example, in Patent Document 1, a metal / oxide composite blackening film containing nickel and zinc metals and oxides of these metals is formed on the surface of a steel sheet to which zinc-based plating has been applied. A technique relating to a blackened steel sheet (non-chromium-type black-treated zinc-plated steel sheet) on which a non-chromium-type anticorrosive film layer containing at least one of a carbonyl group-containing compound and a vanadium compound and a resin is formed is described.

  In this blackened steel sheet, nickel and zinc hydroxides can be contained in the metal / oxide composite blackened film, and the non-chromium type rust preventive film layer includes a phosphoric acid compound and fine silica. At least one of these can also be contained. A resin layer can be arbitrarily formed on the non-chromium type rust preventive film layer, and this resin layer can contain a black pigment.

  On the other hand, Patent Document 2 contains metal ions, water-soluble organic resins, water-dispersible organic resins, acids, and aqueous media in specific ratios to improve the corrosion resistance, scratch resistance, and fingerprint resistance of metal materials. And a technique related to a metal surface treatment composition capable of preventing color change and low gloss.

  In Patent Document 3, a film is formed on the surface of a blackened Zn-Ni plated steel sheet by using a coating composition containing metal ions, a water-soluble organic resin, a water-dispersible organic resin, and an acid. Techniques relating to black steel sheets are described.

  Furthermore, in Patent Document 4, a coating layer of a metal surface treatment composition containing metal ions, acid, and a specific water-dispersible organic resin was formed on the surface of a blackened Zn-Ni plated steel sheet. Techniques relating to black steel sheets are described.

And in patent document 5, the technique regarding the method of forming the organic resin layer containing black pigments, such as carbon black, on the plated steel plate surface which carried out blackening, and also forming a clear resin layer on it is proposed. Yes.
JP 2000-290783 A JP 2001-158969 A JP 2001-164377 A JP 2002-127302 A JP 2002-47579 A

  However, in the steel sheets described in Patent Documents 1, 3, and 4, color unevenness occurs when the non-chromium type rust preventive film layer or oxide layer is formed, or the color tone varies from lot to lot. Sometimes. Such uneven color or variation in color tone has a problem that it is difficult to obtain a steel sheet having an excellent black appearance even if a resin layer containing a black pigment is subsequently formed. Further, even when the metal surface treatment composition described in Patent Document 2 is used, it is difficult to obtain a steel sheet having an excellent black appearance when the metal material to be subjected to the surface treatment has color unevenness. There was a problem of being. Furthermore, the method proposed in Patent Document 5 has a problem in that it is difficult to uniformly disperse the black pigment in the organic resin, so that color unevenness occurs or color tone varies from lot to lot.

  Then, this invention makes it a subject to provide the blackened steel plate which has the outstanding black external appearance and corrosion resistance, and the manufacturing method of the said steel plate.

  The Zn—Ni plated steel sheet can be blackened by oxidizing the Zn—Ni plated film on the surface without depending on the chromate treatment. However, it is difficult to uniformly blacken the entire surface of the Zn-Ni plating film on the surface, resulting in problems such as uneven color, whiteness on the color tone, and variation in color tone from lot to lot. easy.

  Here, the blackening of the Zn-Ni plating film is caused by the fact that the nickel metal present in the plating film is oxidized to produce nickel oxide, while the above-mentioned defects are present on the surface of the plating film. This is due to the fact that zinc is oxidized to produce white zinc oxide. Therefore, after oxidizing the Zn—Ni plating film, it is excellent if only the zinc oxide existing on the surface of the plating film (hereinafter sometimes referred to as “blackening treatment layer”) is selectively removed. A blackened steel sheet having a black appearance can be obtained.

  Therefore, various investigations were made on treatment liquids that can selectively remove only zinc oxide present in the blackening treatment layer. As a result, it is effective to improve the black appearance by immersing the Zn-Ni plated steel sheet having the surface Zn-Ni plated film oxidized in an acidic aqueous solution of pH 2-4 or an alkaline aqueous solution of pH 11-14. And when the said process was performed excessively, it discovered that the corrosion resistance of the said steel plate fell easily.

  Furthermore, this inventor investigated in detail about the surface of the Zn-Ni plating steel plate which performed the blackening process. As a result, the state of the blackening treatment layer greatly affects not only the appearance of the blackened steel sheet but also the corrosion resistance, and the appearance of the blackened steel sheet also greatly affects the centerline average roughness (Ra) of the steel sheet. I found that it was affected. In addition, the present inventors have completed the present invention by examining blackening treatment conditions for obtaining a blackening treatment layer provided in a blackened steel sheet having excellent black appearance and corrosion resistance.

The present invention will be described below.
1st this invention is equipped with the Zn-Ni plating steel plate, the blackening process layer formed in the surface of the said Zn-Ni plating steel plate, and the organic resin layer formed in the outer side of the said blackening process layer, It is a blackened steel plate, and the mass% of metallic nickel, nickel oxide, and zinc oxide contained in the blackened layer is A%, B%, and C%, respectively, and the blackened layer When the surface of P1 is P1, and the blackening treatment layer portion 0.1 μm inside from P1 is P2, (A + B) / (A + B + C) ≧ 0.01 in P1, and (A + B) / (A + B + C) in P2. ) ≦ 0.15 The above problem is solved by a blackened steel sheet.

In the present invention, the center line average roughness Ra of the blackening treatment layer is preferably 1.2 μm or less.
Here, the centerline average roughness Ra refers to an arithmetic average height defined by JIS B0601 Annex 2 “centerline average roughness when a 2RC filter is applied”.

  The second aspect of the present invention is a first step of surface-treating a blackened Zn-Ni plated steel sheet with an acidic aqueous solution of pH 2 to 4 or an alkaline aqueous solution of pH 11 to 14 for 5 to 15 seconds, A blackened steel sheet comprising a second step of washing the Zn-Ni plated steel sheet after one step and a third step of forming a resin film on the surface of the Zn-Ni plated steel plate after the second step. It is a manufacturing method.

  3rd this invention makes the Zn-Ni plating steel plate by which the blackening process was carried out for 5 to 15 seconds by the acidic aqueous solution of pH2-4 prepared without using a chromium compound, or the alkaline aqueous solution of pH11-14. Including a first step of surface treatment, a second step of rinsing the Zn-Ni plated steel plate after the first step, and a third step of forming a resin film on the surface of the Zn-Ni plated steel plate after the second step. Is a method for producing a blackened steel sheet.

  In the second or third aspect of the present invention, the blackening treatment is preferably anodization of a Zn—Ni plated steel sheet.

  According to 1st this invention, in the blackening process layer containing metallic nickel, nickel oxide, and zinc oxide, since the zinc oxide contained in the blackening process layer surface is suppressed to less than 99 mass%, the outstanding black external appearance The blackened steel plate which has can be provided. In addition, the total mass of metallic nickel and nickel oxide contained in the blackening treatment layer 0.1 μm inside from the surface of the blackening treatment layer is based on the total mass of metallic nickel, nickel oxide, and zinc oxide contained in the same layer. Therefore, a blackened steel sheet having excellent corrosion resistance can be provided. Therefore, according to 1st this invention, it becomes possible to provide the blackened steel plate which has the outstanding black external appearance and corrosion resistance.

  Moreover, in 1st this invention, the centerline average roughness Ra of a blackening process layer shall be 1.2 micrometers or less, and an organic resin layer is outside the blackening process layer (for example, the surface of a blackening process layer). Can be formed uniformly. Therefore, it becomes possible to provide a blackened steel sheet having a more excellent black appearance and corrosion resistance.

  According to the second aspect of the present invention, zinc oxide on the blackened Zn-Ni plated steel sheet surface is selectively removed by surface treatment with an acidic aqueous solution of pH 2-4 or an alkaline aqueous solution of pH 11-14. Nickel oxide remains on the steel sheet surface without being removed. Thereafter, the aqueous solution is removed by washing with water, and then a resin film is formed on the surface of the Zn-Ni plated steel sheet, thereby chemically stabilizing the surface of the blackening treatment layer after the zinc oxide is selectively removed. As a result, a blackened steel sheet having excellent corrosion resistance can be obtained. Therefore, according to 2nd this invention, the manufacturing method of the blackened steel plate which can manufacture the blackened steel plate which has the outstanding black external appearance and corrosion resistance can be provided.

  According to the third aspect of the present invention, the surface treatment is performed with an acidic aqueous solution having a pH of 2 to 4 or an alkaline aqueous solution having a pH of 11 to 14 prepared without using a chromium compound such as chromic acid or chromate, thereby blackening treatment. Zinc oxide on the surface of the Zn-Ni plated steel sheet is selectively removed, and nickel oxide remains on the steel sheet surface without being removed. Thereafter, the aqueous solution is removed by washing with water, and then a resin film is formed on the surface of the Zn-Ni plated steel sheet to chemically stabilize the film surface after selectively removing zinc oxide. As a result, a blackened steel sheet having excellent corrosion resistance can be obtained. Therefore, according to 3rd this invention, the manufacturing method of the blackened steel plate which can manufacture the chromium free blackened steel plate which has the outstanding black external appearance and corrosion resistance can be provided.

  Furthermore, in the second and third present inventions, by performing blackening treatment on the Zn—Ni plated steel plate by anodization, it becomes possible to perform a beautiful and uniform blackening treatment on the steel plate. Therefore, the manufacturing method of the blackened steel plate which can manufacture the blackened steel plate which has much more excellent black external appearance and corrosion resistance by setting it as this form can be provided.

Embodiments of the present invention will be described below.
1. Blackened steel sheet 1.1. Zn-Ni-plated steel sheet The Zn-Ni-plated steel sheet constituting the blackened steel sheet of the present invention is not particularly limited as long as it is a steel sheet in which Zn-Ni plating is applied to the base steel sheet, but it is beautiful and uniform. From the viewpoint of obtaining a blackened steel sheet having a blackened and excellent black appearance, the Zn—Ni plating adhesion amount is 5 to 40 g / m ² , and the Ni content in the Zn—Ni plating film is 5 to 30%. A Zn—Ni plated steel sheet is preferred. The Ni content in the Zn—Ni plating film is more preferably 10 to 15%. Further, the type of the base steel plate according to the blackened steel plate of the present invention is not particularly limited, and is for general use such as SPCC, SPCD, SPCE, etc. defined by JIS G 3141, for drawing, or for deep drawing. Various steel sheets such as a high-tensile steel sheet having a tensile strength of 340 MPa or more can be used as well as the cold-rolled steel sheet. The composition of Zn—Ni plating and the amount of adhesion and the type of base steel plate on the blackened steel plate of the present invention can be appropriately selected according to the intended use and grade of the blackened steel plate.

1.2. Blackening treatment layer The black appearance of the blackened steel sheet varies depending on the ratio of metallic nickel, nickel oxide, and zinc oxide present on the surface of the blackened Zn-Ni plating film. As the degree of blackness decreases, the color tone varies. On the other hand, the state of the blackening treatment layer also affects the corrosion resistance of the blackened steel sheet. Therefore, the mass percentages of metallic nickel, nickel oxide, and zinc oxide contained in the blackening treatment layer according to the present invention are A%, B%, and C%, respectively, and the surface of the blackening treatment layer Where P1 is the blackening treatment layer portion 0.1 μm inside from P1, and P1 is (A + B) / (A + B + C) ≧ 0.01 (1)
And in P2,
(A + B) / (A + B + C) ≦ 0.15 (2)
And

  In the above P1, if metal nickel, nickel oxide, and zinc oxide are present so as to satisfy the above formula 1, the presence ratio of zinc oxide in the P1 is less than 99%, so the steel sheet according to the present invention is excellent. It can be set as the steel plate which has a black external appearance. On the other hand, a blackened steel sheet having excellent corrosion resistance can be obtained by allowing metallic nickel, nickel oxide, and zinc oxide to exist so as to satisfy the above formula 2 in P2 of the blackening treatment layer. Therefore, it becomes possible to provide the blackened steel plate which has the outstanding black external appearance and corrosion resistance by setting it as the steel plate which satisfy | fills the said Formula 1 and 2.

Further, in the blackened steel sheet according to the present invention, from the viewpoint of obtaining a steel sheet having a more excellent black appearance and corrosion resistance, the center line average roughness Ra (hereinafter referred to as “surface roughness Ra”) in the blackening treatment layer. Is preferably 1.2 μm or less. By setting it as such a form, since the unevenness | corrugation on the blackening process layer surface decreases, it becomes possible to form an organic resin layer uniformly on the surface of a blackening process layer.
In the present invention, the lower limit value of Ra is not particularly limited, but is 0.4 μm or more from the viewpoint of preventing the blackened treatment layer surface from becoming too flat and giving a black appearance of a shining impression. It is preferable that In addition, the method of obtaining the blackening process layer which is such a value of Ra is not specifically limited, For example, Ra of the base material steel plate surface to which Zn-Ni plating is given shall be about the said range. And the like.

1.3. Organic resin layer In the blackened steel sheet of the present invention, an organic resin layer is formed outside the blackened layer (for example, the surface of the blackened layer). The method for forming the organic resin layer according to the present invention is not particularly limited. For example, the organic resin layer is formed by applying an organic resin to the surface of the blackening treatment layer and then drying or baking the organic resin layer. Can be made.
In the present invention, the organic resin layer applied to the surface of the blackening treatment layer is not particularly limited. For example, an acrylic resin, a urethane resin, a polyester resin, or a phenol resin is preferably applied. be able to.
Furthermore, the chemical solution used when applying the organic resin is not particularly limited. For example, an organic chemical solution in which the resin is dissolved in an organic solvent, or an aqueous dispersion chemical solution in which the resin is dispersed in water. Etc. can be used suitably.
In addition, the organic resin layer according to the present invention may further contain an organic or inorganic inhibitor, a rust inhibitor, a surfactant, a coupling agent, or the like as long as the main component is an organic resin. In addition, the organic resin layer may contain a pigment component such as carbon black, but from the viewpoint of utilizing the color of the blackening treatment layer, the pigment component is preferably not included.
The thickness of the organic resin layer to be formed on the surface of the blackening treatment layer is not particularly limited, but is 0.1 μm or more from the viewpoint of obtaining a blackened steel sheet that is generally easy to use. Is preferable, and it is preferable that it is 10 micrometers or less.

2. The manufacturing method of the blackened steel plate The manufacturing method of the blackened steel plate of this invention contains the 1st process, the 2nd process, and the 3rd process. Therefore, embodiments of each process will be described below.

2.1. First Step The first step is a step of surface-treating the blackened Zn—Ni plated steel sheet with an acidic aqueous solution of pH 2 to 4 or an alkaline aqueous solution of pH 11 to 14 for 5 to 15 seconds.

  The blackening treatment method of the Zn—Ni plated steel sheet according to the present invention is not particularly limited, but from the viewpoint of reducing environmental burden, it is possible to use Zn—Ni without using chromium-containing substances such as chromic acid and chromate. A method capable of oxidizing the plating film is preferable. Specific examples of such a method include a method using anodic electrolytic oxidation, a method of immersing in an oxidizing liquid, a method using alternating electrolysis, and the like. Among these methods, it is preferable to use a method based on anodic electrolytic oxidation from the viewpoint of easily obtaining a beautifully and uniformly blackened steel sheet, and in particular, an anode in an aqueous solution of an oxidizing acid such as nitric acid. More preferably, a method of electrolytic oxidation is used.

  As the blackened Zn—Ni plated steel sheet used in the present invention, a steel sheet that can be used in the blackened steel sheet of the present invention can be suitably used. Therefore, as described above, the Zn—Ni plating adhesion amount, the plating composition, and the base steel plate can be appropriately selected according to the intended use, grade, etc. of the blackened steel plate.

  In the first step of the present invention, the surface of the blackened Zn—Ni plated steel sheet is treated with an acidic aqueous solution or an alkaline aqueous solution for 5 to 15 seconds. By performing such a treatment, the zinc oxide in the blackening treatment layer can be selectively removed to make the presence ratio of the zinc oxide less than 99%, so that a blackened steel sheet having an excellent black appearance is provided. It becomes possible. In addition, by performing such treatment, the total mass of the nickel metal and nickel oxide contained in the blackening treatment layer 0.1 μm inside from the surface of the blackening treatment layer is the same as that of the nickel metal, nickel oxide, and Since it becomes 15% or more with respect to the total mass of a zinc oxide, it becomes possible to provide the blackened steel plate which has the outstanding black external appearance and corrosion resistance.

In the surface treatment in the first step of the present invention, the zinc oxide on the surface of the Zn-Ni plating film subjected to blackening treatment is selectively used by utilizing the solubility of zinc oxide and nickel oxide in an acidic aqueous solution or an alkaline aqueous solution. It has been removed. That is, with zinc oxide and nickel oxide,
i) Utilizing the fact that zinc oxide is more soluble in acidic solution than nickel oxide, or
ii) While nickel oxide does not dissolve in an alkaline aqueous solution, zinc oxide dissolves in an alkaline aqueous solution having a pH of 11 or more.
Zinc oxide on the surface of the Zn-Ni plating film that has been blackened is selectively removed.

  The pH of the acidic aqueous solution according to the first step of the present invention is set to 2 or more from the viewpoint of appropriately performing selective removal of zinc oxide. Furthermore, from the viewpoint of dissolving zinc oxide at an appropriate dissolution rate, the pH is set to 4 or less. The acidic aqueous solution that can be used in the first step of the present invention is not particularly limited as long as it is an acidic aqueous solution having a pH of 2 to 4, but a chromium compound is used from the viewpoint of reducing environmental burden. It is preferable that it has been prepared. Such an acidic aqueous solution can be prepared using, for example, an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, an organic acid such as formic acid and acetic acid, or a mixture of an inorganic acid and an organic acid. Among these, hydrochloric acid, sulfuric acid, and nitric acid can be preferably used from the viewpoint of availability.

  On the other hand, the pH of the alkaline aqueous solution according to the first step of the present invention is set to 11 or more from the viewpoint of effectively selectively removing zinc oxide. The alkaline aqueous solution that can be used in the first step of the present invention is not particularly limited as long as the pH is an alkaline aqueous solution of 11 to 14, but, similarly to the case of the acidic aqueous solution, from the viewpoint of reducing environmental burden. It is preferably prepared without using a chromium compound. Such an alkaline aqueous solution can be prepared using, for example, an inorganic alkali such as sodium hydroxide, potassium hydroxide, and calcium hydroxide, an organic alkali such as dimethylamine, or a mixture of an inorganic alkali and an organic alkali. it can. Of these, sodium hydroxide and potassium hydroxide can be suitably used from the viewpoint of availability.

  On the other hand, the time of the surface treatment according to the present invention performed by a method such as immersing the Zn-Ni plated steel sheet in the treatment liquid or spraying the treatment liquid on both surfaces of the Zn-Ni plated steel sheet is excellent. From the viewpoint of obtaining a blackened steel sheet having a black appearance and corrosion resistance, the time is set to 5 seconds or more. In addition, from the viewpoint of preventing excessive selective removal of zinc oxide, the treatment time is set to 15 seconds or less. The temperature of the aqueous solution used in the surface treatment is not particularly limited, but the temperature is about room temperature to about 40 ° C. from the viewpoint of effectively performing selective removal of zinc oxide in the blackening treatment layer. It is preferable that

  Here, as described above, since it is possible to use an oxidizing liquid in the blackening treatment of the Zn-Ni plated steel sheet, the pH of the acidic solution used in the blackening treatment is set to 2 to 4. For example, zinc oxide can be selectively removed in the same treatment tank following the blackening treatment. By adopting such a form, the first step can be simplified by omitting the cleaning / drying step conventionally performed between the step of blackening treatment and the step of immersion in an acidic or alkaline aqueous solution. it can.

2.2. Second Step The second step of the present invention is a step in which the acidic aqueous solution or alkaline aqueous solution attached to the surface of the Zn—Ni plated steel sheet in the first step is washed away with water. The water used in the second step of the present invention is not particularly limited as long as the acidic aqueous solution or the alkaline aqueous solution can be washed away. For example, ion-exchanged water, clean water, or industrial water is preferable. Can be used for Moreover, the method of washing with water is not particularly limited, and for example, a method such as immersion or spraying can be used. Furthermore, the temperature and flow rate of water used for water washing are not particularly limited, and a temperature and a flow rate at which an appropriate washing effect can be obtained can be appropriately selected.

  The water adhering to the surface of the Zn—Ni plated steel sheet in the second step of the present invention is sufficiently removed by a drying furnace or the like. Here, the form of the drying furnace to be used is not particularly limited, and for example, a normal heating-type drying furnace, a blower-type drying furnace, a vacuum drying furnace, or the like can be suitably used.

2.3. 3rd process The 3rd process of this invention is a process of forming a resin film in the surface of the blackening process layer in the Zn-Ni plating steel plate which passed through the said 2nd process. The resin film forming method in the third step of the present invention is not particularly limited. For example, the organic resin layer is formed by applying an organic resin to the surface of the blackening treatment layer and then drying or baking. Can be formed. By forming the organic resin layer on the surface of the blackening treatment layer in this way, it is possible to prevent the black appearance of the steel sheet surface from being damaged.

Hereinafter, the present invention will be described in more detail based on examples.
1. Preparation of test material Zn- having a surface roughness Ra of cold rolled steel sheet as a base steel sheet, the Ni base material having a Ni content of 12.5% and a plating adhesion of 20 g / m ² Ni plating was performed to obtain a Zn-Ni plated steel sheet. And this blackening process was performed with respect to this Zn-Ni plating steel plate by the following three methods.
(X) Anodic electrooxidation: A blackening film is formed on the surface of the Zn-Ni plated steel sheet by anodic electrooxidation in an aqueous solution of sodium nitrate 30 g / L at an energization amount of 20 A / dm ² and 130 C / dm ^2. Generate. The Zn—Ni plated steel sheet on which the blackened film is thus formed is then washed with water and subsequently dried to obtain an analytical test material.
(Y) Alternating electrolysis: A blackening film is formed on the surface of the Zn-Ni plated steel sheet by performing alternating electrolysis in an aqueous solution of sodium nitrate 30 g / L at a current of 20 A / dm ² , 200 C / dm ² , 60 Hz. Generate. The Zn—Ni plated steel sheet on which the blackened film is thus formed is then washed with water and subsequently dried to obtain an analytical test material.
(Z) Nitric acid immersion: A blackening film is formed on the surface of the plated steel sheet by immersing the Zn-Ni plated steel sheet in a 1N nitric acid solution at 50 ° C for 10 seconds. The Zn—Ni plated steel sheet on which the blackened film is thus formed is then washed with water and subsequently dried to obtain an analytical test material.
The analytical test material subjected to blackening treatment by the above three methods was immersed in an acidic or alkaline aqueous solution, washed and dried, and subjected to surface analysis. After the drying, a resin is further applied to the surface, and after baking in an oven so that the steel sheet temperature becomes 120 ° C., the surface roughness, color difference, and corrosion resistance test material (blackened steel sheet) It was. Blackening treatment method (X, Y, and Z above) when preparing the test material, the type of aqueous solution used (acidity: x, y, alkalinity: z, no use:-), surface roughness Ra of the base steel plate, Table 1 shows the surface treatment time, the concentration of the aqueous solution, the temperature and flow rate, the type and thickness of the formed resin, and the results of surface analysis, color difference, and corrosion resistance, which will be described later.

なお、表１において、ｘはｐＨ２．５に調製した硫酸を、ｙはｐＨ３．５に調製した硫酸を、ｚはｐＨ１１．５に調製した水酸化ナトリウム水溶液を用いて表面処理を行ったことを、それぞれ表している。

In Table 1, x is a surface treatment using sulfuric acid adjusted to pH 2.5, y is sulfuric acid adjusted to pH 3.5, and z is a sodium hydroxide aqueous solution adjusted to pH 11.5. , Respectively.

2. Analysis method and evaluation method 2.1. Surface Analysis Analytical test materials prepared by the above-described method were analyzed using Shimadzu X-ray photoelectron spectrometer EACA3200 manufactured by Shimadzu Corporation. Here, the blackening treatment layer surface P1 was analyzed without performing sputtering with Ar. On the other hand, the value in the case of performing sputtering with Ar for 120 seconds was taken as the analysis result in the blackening treatment layer P2 0.1 μm below the surface. In this analysis, Ar sputtering attached to the ESCA analyzer was a sputtering amount of 0.65 nm per _{second in} terms of SiO ₂ .

  The Ni / 2p peak and the Zn / LM peak obtained from the wide scan in the ESCA 3200 are identified by narrow scan, and then separated into peaks of metal nickel, nickel oxide, and zinc oxide by separating the peaks, and The existence ratio of each atom in P1 and P2 was calculated. The calculation results are shown in Table 1.

2.2. Surface Roughness Measurement Centerline roughness Ra was measured using the SURF TEST SV-600 manufactured by Mitutoyo Corporation for the analytical test material produced by the method described above. The measurement results are shown in Table 1.

2.3. Performance evaluation 2.3.1. Color difference (black appearance)
The color difference (L value in Hunter Lab color system) of the test material produced by the method described above was measured with a color difference meter SM-7-IS-2B manufactured by Suga Test Instruments. The measurement results and evaluation are shown in Table 1. Here, the L value is an average value of measurement results at three neighboring points.
The color difference (black appearance) was evaluated based on the following criteria.
<Evaluation criteria>
L ≦ 23: ◎ = Excellent 23 <L ≦ 24: ○ = Good 24 <L ≦ 25: Δ = Slightly inferior 25 <L: × = Inferior

2.3.2. Corrosion resistance Specified in JIS Z2371 “Salt spray test method” on the surface coated with the above surface treatment liquid after sealing the back and end surfaces of the test material cut so that the corrosion resistance evaluation surface has a size of 70 mm × 150 mm with tape. The salt spray test that has been performed was performed for 120 hours, and the occurrence of white rust on the corrosion resistance evaluation surface was observed. Corrosion resistance evaluation was performed based on the following criteria. Table 1 shows the evaluation results of the corrosion resistance.
<Evaluation criteria>
Ratio of white rust generation area in the evaluation surface is 2% or less: ◎ = Excellent Ratio of white rust generation area in the evaluation surface exceeds 2% and 5% or less: ○ = Good Ratio of white rust generation area in the evaluation surface Is more than 5% and not more than 20%: Δ = Slightly defective The ratio of white rust generation area in the evaluation surface exceeds 20%: × = Defective

3. Evaluation results As shown in Table 1, when the mass percentages of metallic nickel, nickel oxide, and zinc oxide contained in the blackening treatment layer are A%, B%, and C%, respectively, in Examples 1 to 16, The value of “(A + B) / (A + B + C)” in P1 (hereinafter referred to as “mass ratio”) was 0.01 or more, and the mass ratio in P2 was 0.15 or less. Therefore, the test materials according to Examples 1 to 16 had excellent black appearance and corrosion resistance. In addition, among these Examples 1 to 16, the black appearance was particularly excellent in the test materials according to Examples 7 to 12, 14, and 16 in which the surface roughness Ra was 1.2 or less. On the other hand, as shown in Table 1, in the test materials according to Comparative Examples 1 to 10, at least the mass ratio in P1 is less than 0.01, or the mass ratio in P2 exceeds 0.15. Therefore, the black appearance and / or corrosion resistance were inferior to the test materials according to Examples 1 to 16. As mentioned above, according to this invention, it was confirmed that the blackened steel plate which has the outstanding black external appearance and corrosion resistance is obtained.

Claims (3)

A first step of surface-treating the blackened Zn-Ni plated steel sheet with an acidic aqueous solution of pH 2 to 4 for 5 to 15 seconds;
A second step of rinsing the Zn-Ni plated steel sheet after the first step;
A third step of forming a resin film on the surface of the Zn-Ni plated steel sheet after the second step;
The manufacturing method of the blackening steel plate characterized by including. A first step of surface-treating the blackened Zn-Ni plated steel sheet for 5 to 15 seconds with an acidic aqueous solution of pH 2 to 4 prepared without using a chromium compound;
A second step of rinsing the Zn-Ni plated steel sheet after the first step;
A third step of forming a resin film on the surface of the Zn-Ni plated steel sheet after the second step;
The manufacturing method of the blackening steel plate characterized by including. The method for producing a blackened steel sheet according to claim 1 or 2, wherein the blackening treatment is to anodize a Zn-Ni plated steel sheet.