JP6852454B2 - Manufacturing method of Sn-based alloy-plated steel sheet and Sn-based alloy-plated steel sheet - Google Patents

Description

The present invention relates to a Sn-based alloy-plated steel sheet and a method for manufacturing a Sn-based alloy-plated steel sheet.

Sn (tin) alloy plated steel sheets are widely used as steel sheets for containers such as beverage cans and food cans. This is because Sn is a beautiful metal that is safe for the human body. This Sn-based alloy-plated steel sheet is hexavalent chromate in order to ensure the adhesion and corrosion resistance between the steel sheet and the coating film and to suppress the appearance change (yellowing) due to the growth of tin oxide during storage before painting. A chromate film is often applied on a Sn-based alloy-plated steel sheet by a chromate treatment such as an electrolytic treatment using a salt solution or a dipping treatment. The effect of this chromate film is to prevent blackening of sulfide that produces black sulfide by the reaction of S in the contents with Sn and Fe, and to prevent yellowing of the appearance by suppressing oxidation of the Sn plating surface. In addition, it is possible to prevent deterioration of coating adhesion due to cohesive destruction of tin oxide when it is painted and used.

On the other hand, in recent years, due to increasing awareness of the environment and safety, it is required not only that the final product does not contain hexavalent chromium but also that the chromate treatment itself is not performed. However, as described above, the steel sheet for containers made of Sn-based alloy-plated steel sheet without a chromate film has a reduced blackening resistance to sulfurization, a yellowing of the appearance due to the growth of tin oxide, and a reduced adhesion to the coating film. Or

For this reason, some steel sheets for containers that have been treated with a film instead of the chromate film have been proposed.

For example, Patent Document 1 below proposes a Sn-plated steel plate in which a film containing P and Si is formed by a treatment using a solution containing a phosphate ion and a silane coupling agent. In Document 2, a Sn-plated steel plate in which a film containing a reaction product of Al and P, at least one of Ni, Co, and Cu and a silane coupling agent is formed by a treatment using a solution containing aluminum phosphate is formed. Has been proposed. Further, Patent Document 3 below proposes a method for producing a Sn-plated steel sheet having no chromate film, in which Zn plating is performed on Sn plating and then heat treatment is performed until the Zn single plating layer disappears. Further, the following Patent Documents 4 and 5 propose a steel sheet for a container having a chemical conversion treatment film containing zirconium, phosphoric acid, phenol resin and the like.

Japanese Unexamined Patent Publication No. 2004-60052 Japanese Unexamined Patent Publication No. 2011-174172 Japanese Unexamined Patent Publication No. 63-290292 JP-A-2007-284789 Japanese Unexamined Patent Publication No. 2010-13728

However, the steel sheet for containers and the method for producing the steel sheet for containers proposed in Patent Documents 1 to 5 are insufficient in blackening resistance to sulfide blackening, and the growth of tin oxide with time cannot be sufficiently suppressed. There was a problem that it was inferior in yellowing resistance and coating adhesion.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is black sulfide modification, yellowing resistance, and coating film adhesion without performing conventional chromate treatment. It is an object of the present invention to provide a more excellent method for producing a Sn-based alloy-plated steel sheet and a Sn-based alloy-plated steel sheet.

As a result of diligent studies by the present inventor in order to solve the above problems, by forming a layer containing a specific zirconium oxide on the surface of a Sn-based alloy-plated steel sheet, sulfide-resistant blackening is not performed without chromate treatment. It has been found that a Sn-based alloy-plated steel sheet having further excellent yellowing resistance and coating adhesion can be realized.

The gist of the present invention completed based on the above findings is as follows.
(1) Steel plate and
A composite plating layer having a Fe—Ni—Sn alloy layer located on at least one surface of the steel sheet and island-shaped Sn located on the Fe—Ni—Sn alloy layer, and
A film layer located on the composite plating layer and containing zirconium oxide and tin oxide,
Have
The amount of the zirconium oxide adhered to the pre-film layer is 0.2 mg / m ² or more and 50 mg / m ² or less in terms of the amount of metal Zr.
The film layer is a Sn-based alloy containing a zirconium oxide in which the peak position of the binding energy of Zr3d5 / 2 by XPS (X-ray Photoelectron Spectroscopy) is 182.5 eV or more and 182.9 eV or less. Plated steel plate.
( 2 ) The Sn-based alloy-plated steel sheet according to (1 ), wherein the amount of electricity required for reduction of the tin oxide is 0.2 mC / cm ² or more and 5.0 mC / cm ² or less.
( 3 ) The composite plating layer contains Ni in terms of Ni of 2 mg / m ² or more and 200 mg / m ² or less and Sn of 0.1 g / m ² or more and 10 g / m ² or less in terms of Sn. The Sn-based alloy-plated steel sheet according to (1) or (2), which contains.
( 4 ) An Fe-Ni—Sn alloy layer containing Ni and Sn on at least one surface of the steel plate and alloying a part or all of Ni and a part of Sn by melt heat treatment, and the Fe-Ni. Immersion of a Sn-based alloy-plated steel plate having an island-shaped Sn located on the −Sn alloy layer and a composite plating layer on which a tin alloy layer is formed in a solution containing zirconium ions or cathode electrolysis in a solution containing zirconium ions By the treatment, a zirconium oxide is generated on the composite plating layer,
The Sn-based alloy-plated steel sheet was subjected to anodic electrolysis treatment in an electrolyte solution.
A method for producing a Sn-based alloy-plated steel sheet in which the amount of electricity in the anodic electrolysis treatment is 0.1 / dm ² or more and 6.4 C / dm ^{2 or less.}
( 5 ) The method for producing a Sn-based alloy-plated steel sheet according to (4 ), wherein the anodic electrolysis treatment is carried out in the electrolyte solution having a pH of 3 or more and 14 or less.

As described above, according to the present invention, a method for producing a Sn-based alloy-plated steel sheet and a Sn-based alloy-plated steel sheet, which are more excellent in sulfide blackening resistance, yellowing resistance, and coating adhesion, without performing conventional chromate treatment. Can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The present invention described below relates to a steel sheet for containers widely used for cans such as food cans and beverage cans, and a method for manufacturing such a steel sheet for containers. More specifically, the present invention relates to a method for producing a Sn-based alloy-plated steel sheet and a Sn-based alloy-plated steel sheet, which are more excellent in black sulfide resistance, yellowing resistance, and coating film adhesion without performing conventional chromate treatment.

<1. Sn-based alloy plated steel sheet>
The Sn-based alloy-plated steel sheet according to the present embodiment contains a composite plating layer (Sn-based alloy plating layer) located on at least one surface of the steel sheet and a predetermined amount of zinc oxide located on the composite plating layer. It has a coating layer to be formed.

More specifically, the Sn-based alloy-plated steel sheet according to the present embodiment contains Ni and Sn on at least one surface of the steel sheet, and a part or all of Ni and a part of Sn are alloyed by melt heat treatment. A zirconium oxide is placed on a Sn-based alloy-plated steel plate having a obtained Fe-Ni-Sn alloy layer and a composite plating layer located on the Fe-Ni-Sn alloy layer and in which island-shaped Sn is generated. Has a film layer containing. That is, in the Sn-based alloy-plated steel sheet according to the present embodiment, the above-mentioned film layer is formed on the composite plating layer. In the Sn-based alloy-plated steel sheet according to the present embodiment, the content of zirconium oxide in the film layer is 0.2 mg / m ² or more and 50 mg / m ² or less per side in terms of the amount of metal Zr. Further, in the Sn-based alloy plated steel plate according to the present embodiment, the peak position of the binding energy of Zr3d5 / 2 by XPS (X-ray Photoelectron Spectroscopy) of the zirconium oxide in the film layer is 182. Contains zirconium oxides of 5 eV or more and 182.9 eV or less.

[1.1 Steel plate]
The steel sheet used as the base material for the Sn-based alloy-plated steel sheet according to the present embodiment is not particularly specified, and any steel sheet used for general container steel sheets can be used. Yes, for example, low carbon steel and ultra-low carbon steel can be mentioned.

[1.2 Composite plating layer (Sn-based alloy plating layer)]
A composite plating layer is formed on at least one side of the steel sheet as described above. This composite plating layer contains a Fe-Ni-Sn alloy layer containing Ni and Sn, and a part or all of Ni and a part of Sn are alloyed by a melt heat treatment, and such Fe-Ni-Sn. It is composed of island-shaped Sn located on the alloy layer.

(Fe-Ni-Sn alloy layer)
The Fe—Ni—Sn alloy layer has the effect of improving corrosion resistance. This is because Ni and Sn, which are electrochemically noble metals than iron, form an alloy layer of Fe, thereby improving the corrosion resistance of Fe itself.

The effect of improving the corrosion resistance by Ni is determined by the amount of Ni in the Ni plating layer or the Fe—Ni plating layer generated on the steel sheet in order to form the composite plating layer on the steel sheet. When the amount of Ni is 2 mg / m ² or more per side as a Ni equivalent amount, the effect of corrosion resistance is exhibited. The larger the amount of Ni, the greater the effect of improving corrosion resistance. If the Ni conversion amount ^{exceeds 200 mg / m 2} per side, the effect of improving the corrosion resistance is saturated, and even if it is increased more than that, it is economically unfavorable. Further, if the Ni conversion amount is 200 mg / m ² or less per side, the sulfurization-resistant blackening can be made excellent. Therefore, the amount of Ni is especially but not limited to, for example, considering the above, it is possible to per side 2 mg / ^{m 2} or more 200 mg / ^{m 2} or less as Ni equivalent amount. The amount of Ni is more preferably 2 mg / m ² or more and 180 mg / m ² or less per side as a Ni conversion amount. The Ni content in the composite plating layer also corresponds to the Ni content in the Fe—Ni—Sn alloy layer.

[Island Sn]
The island-shaped Sn generated on the Fe—Ni—Sn alloy layer has an effect of improving corrosion resistance and coating film adhesion. Sn is a metal that is more noble than iron in an air-corrosion environment, and as a barrier-type film, it prevents Fe from corroding. On the other hand, in an acid-corrosion environment such as an acidic beverage can, it sacrifices iron to provide corrosion resistance. Improve. Further, the presence of Sn in an island shape improves the adhesion of the coating film by the anchor effect and the effect of suppressing the growth of tin oxide due to the presence of the Fe—Ni—Sn alloy layer corresponding to the sea part. Further, by suppressing the growth of tin oxide, there is an effect of suppressing yellowing.

Since the island-shaped Sn exerts an effect together with the Fe—Ni—Sn alloy layer, the Sn amount in the island-shaped Sn is related to the Sn amount of the entire composite plating layer and its effect. The amount of Sn is not particularly limited in order to exert the effect of improving the corrosion resistance and the effect of improving the adhesion of the coating film by the island-shaped Sn, but for example, in the composite plating layer, the Sn conversion amount is 0.1 g / g per side. It is preferably m ^{2 or more.} As the amount of Sn increases, the effects of improving corrosion resistance and coating film adhesion increase. On the other hand, when the Sn conversion amount is 10 g / m ² or less per side, the effect of improving the corrosion resistance can be sufficiently obtained while suppressing the decrease in adhesion and the increase in cost. ^{Therefore, the amount of Sn is preferably 0.1 g / m 2} or more and 10 g / m ² or less per side in terms of Sn conversion amount in the composite plating layer. The amount of Sn is more preferably 0.2 g / m ² or more and 8 g / m ² or less per side as a Sn conversion amount.

[1.3 Zirconium oxide-containing film layer]
The Sn-based alloy-plated steel sheet according to the present embodiment has a film layer containing a zirconium oxide on the surface of the composite plating layer. The content of zirconium oxide in such a film layer is 0.2 mg / m ² or more and 50 mg / m ² or less per side in terms of the amount of metal Zr, and the peak position of the binding energy of Zr3d5 / 2 by XPS is 182.5 eV. It contains a zirconium oxide having a value of 182.9 eV or less.

The above Zr3d5 / 2 is described on page 83 of, for example, "X-ray photoelectron spectroscopy (surface analytical chemistry selection)" (edited by the Surface Science Society of Japan, Japan, Maruzen Co., Ltd., July 1998). In the same way that / 2 indicates the electron orbit of Sn, it indicates the electron orbit of Zr. The reason for paying attention to the electron orbital of Zr3d5 / 2 is that the electron orbital has a large photoionization cross section and a high photoelectron intensity can be obtained.

The Sn-based alloy-plated steel sheet according to the present embodiment has a film layer in which the above-mentioned zirconium oxide and tin oxide coexist on the surface of the composite plating layer, so that it is resistant to blackening and yellowing, and adheres to the coating film. The sex can be further improved. The tin oxide alone or the zirconium oxide alone cannot sufficiently improve the yellowing resistance, the coating film adhesion, and the sulfurization blackening resistance. The reason for this is not clear, but the detailed investigation by the present inventors considers it as follows.

In the conventional method of forming a zirconium oxide on a Sn-plated steel plate as shown in, for example, Patent Document 3 or 4, the zirconium oxide is produced by utilizing the pH increase accompanying hydrogen generation from the Sn-plated surface by cathode electrolysis. This is a method of generating on the Sn-plated surface, but especially when the cathode current density is high, the rapidly generated hydrogen itself inhibits the precipitation of zirconium oxide on the Sn-plated surface, so that coarse zirconium oxide or oxygen It is considered that unstable zirconium oxide deficient in cathode is likely to be produced. For this reason, the barrier property of the film containing the zirconium oxide becomes insufficient, and the reaction of S with Sn and Fe causes blackening of sulfide, and the permeation of oxygen over time causes the tin oxide to grow and turn yellow. Further, the adhesion of the coating film is inferior as the tin oxide grows. According to the investigation by the inventors, the peak position of the binding energy of Zr3d5 / 2 by XPS of the zirconium oxide produced by these methods was 181.9 eV or more and less than 182.5 eV.

Therefore, the present inventors attempted to improve these coarse and oxygen-deficient unstable zirconium oxides, and the peak position of the binding energy of Zr3d5 / 2 by XPS is 182.5 eV or more and 182.9 eV or less. It was found that yellowing, blackening of sulfide, and coating adhesion with time can be improved by forming the above on a Sn-based alloy-plated steel sheet. It is presumed that this is because the zirconium oxide, which has a higher binding energy than before, increases the stability of the zirconium compound and improves the barrier property.

The greater the binding energy, the better the stability and barrier properties of the zirconium oxide, but if it is excessive, the coating film adhesion tends to be inferior. Therefore, the peak position of the binding energy of Zr3d5 / 2 is 182.5 eV or more. It needs to be 182.9 eV or less, and more preferably 182.6 eV or more and 182.8 eV or less. When the binding energy position is less than 182.5 eV, the stability and barrier property of the zirconium oxide are insufficient, and the sulfurization blackening resistance and the yellowing resistance are inferior. On the other hand, when the binding energy position exceeds 182.9 eV, the adhesion to the coating film is inferior, which is not preferable. In XPS, the spectrum and peak position may shift (charge shift) due to the influence of charge of the sample, so the peak position due to contaminants (organic carbon) adsorbed on the surface of the sample. Make corrections. Specifically, the binding energy position of Zr3d5 / 2 was determined after shifting the entire spectrum so that the peak position of carbon (C1s) detected on the surface of the sample was 284.8 eV.

The amount of the zirconium oxide adhered needs to be ^{0.2 mg / m 2} or more and 50 mg / m ^{2 or less in terms of the amount of metal Zr.} If it is less than 0.2 mg / m ² , it is inferior in sulfurization blackening resistance, ^{and if it exceeds 50 mg / m 2} , it is inferior in coating film adhesion. The preferred range is 0.5 mg / m ² or more and 25 mg / m ² or less, and the more preferable range is 1.0 mg / m ² or more and 10 mg / m ² or less. The amount of Zr adhered is determined by immersing a Sn-based alloy-plated steel plate having a film layer according to the present embodiment on its surface in an acidic solution such as hydrofluoric acid and sulfuric acid to dissolve it. Is a value measured by chemical analysis such as high frequency inductively coupled plasma (ICP) emission spectrometry. Alternatively, the amount of Zr attached may be determined by fluorescent X-ray measurement.

Further, the film layer preferably contains a tin oxide. Tin oxide is a component that imparts barrier properties to the film layer, and contributes to the improvement of sulfurization blackening resistance and yellowing resistance of the film layer. In particular, when the film layer contains the above-mentioned zirconium oxide and tin oxide at the same time, the sulfurization blackening resistance and the yellowing resistance are further improved as compared with the case where each is contained alone.

The amount of electricity required for reduction of tin oxide in the above film layer ^{is preferably 0.2 mC / cm 2} or more and 5.0 mC / cm ² or less. When the amount of electricity required for the reduction of the tin oxide is 5.0 mC / cm ² or less, it is possible to prevent yellowing from the initial stage and deterioration of the coating film adhesion. On the other hand, when the amount of electricity required for the reduction of the tin oxide is 0.2 mC / cm ² or more, the sulfurization blackening resistance can be sufficiently excellent. It is preferably 0.5 mC / cm ² or more and 2.0 mC / cm ² or less.

^{The amount of electricity required for the reduction of tin oxide is 0.06 mA / cm 2} in a 0.001 mol / L hydrobromic acid aqueous solution from which dissolved oxygen has been removed by bubbling nitrogen gas, etc., and the Sn system of the present invention. It can be obtained from the product of the time and current for cathodic electrolysis of an alloy-plated steel plate to reduce and remove tin oxide.

The film layer containing the zirconium oxide and the tin oxide may be in a mixed state of both or in a solid solution of the oxide, and its existence state does not matter. Further, there is no problem even if any element such as Fe, Ni, Cr, Ca, P, Na, Mg, Al, Si and the like is contained in these oxides.

Further, the Sn-based alloy-plated steel sheet according to the present embodiment may have a composite plating layer and a coating layer on at least one surface, and has only one of the composite plating layer and the coating layer on the other surface. It may or may not have both a composite plating layer and a coating layer. Further, the Sn-based alloy-plated steel sheet may have a composite plating layer and a coating layer on both sides. Further, the Sn-based alloy-plated steel sheet according to the present embodiment may have a layer or a film composed of other components on the other surface.

Further, the Sn-based alloy-plated steel sheet according to the present embodiment may be manufactured by any method, and for example, it can be manufactured by the Sn-based alloy-plated steel sheet manufacturing method described below.

<2. Manufacturing method of Sn-based alloy plated steel sheet>
Next, a method for manufacturing a Sn-based alloy-plated steel sheet according to the present embodiment will be described. In the method for producing a Sn-based alloy-plated steel sheet according to the present embodiment, at least one side of the steel sheet contains Ni and Sn, and a part or all of Ni and a part of Sn are alloyed by melt heat treatment. A Sn-based alloy-plated steel sheet having a composite plating layer in which a Fe-Ni-Sn alloy layer and an island-shaped Sn located on the Fe-Ni-Sn alloy layer are formed is placed in a solution containing zirconium ions. A tin oxide oxide is generated on the composite plating layer by immersion or a cathode electrolysis treatment in a solution containing zirconium ions, and the Sn-based alloy-plated steel sheet is subjected to an anode electrolysis treatment in an electrolyte solution.
The amount of electricity in the anode electrolysis treatment is 0.1 / dm ² or more and 6.4 C / dm ² or less.
In this embodiment, a steel sheet is prepared and a composite plating layer is formed on at least one surface of the steel sheet prior to the cathode electrolysis treatment.

[2.1 Preparation of steel plate]
First, a steel sheet to be a base material of a Sn-based alloy-plated steel sheet is prepared. The manufacturing method and material of the steel sheet to be used are not particularly specified, and examples thereof include those manufactured through processes such as casting, hot rolling, pickling, cold rolling, annealing, and temper rolling. it can.

[2.2 Formation of composite plating layer]
Next, on at least one surface of the steel sheet, a composite plating layer in which island-shaped Sn is generated is formed on the Fe—Ni—Sn alloy layer.
In the composite plating layer, a Ni plating layer or a Fe-Ni plating layer as a base is formed on the steel sheet, and a Sn plating layer is further formed on the Ni plating layer or the Fe-Ni plating layer, and then heat melting treatment is performed. It is generated by applying. That is, by the melt heat treatment, Fe of the steel sheet, Ni of the Ni plating layer, and Sn of a part of the Sn plating layer are alloyed to form an Fe—Ni—Sn alloy layer, and the remaining Sn is formed. The plating layer becomes island-shaped Sn.

The Ni plating and Fe-Ni plating methods are not particularly specified, but known electroplating methods can be used, and examples thereof include a plating method using a sulfuric acid bath or a chloride bath. it can.

The method of applying Sn plating to the surface of the Ni plating layer or the Fe—Ni plating layer is not particularly specified, but for example, a known electroplating method is preferable. As the electroplating method, for example, an electrolytic method using a well-known ferrostan bath, halogen bath, alkaline bath, or the like can be used.

After Sn plating, heat melting treatment is performed to heat the plated steel sheet to 231.9 ° C. or higher, which is the melting point of Sn. By this heat melting treatment, the Sn plating is melted and alloyed with the underlying Ni plating layer or Fe-Ni plating layer to form an Fe-Ni-Sn alloy layer, and further, an island-shaped Sn layer is generated. ..

Hereinafter, a method for forming a film layer containing a zirconium oxide according to the present embodiment will be described.

[2.3 Cathode electrolysis treatment]
In order to generate the film layer according to the present embodiment, first, a zirconium oxide layer containing a zirconium oxide is generated on the composite plating layer of the Sn-based alloy-plated steel sheet.

The zirconium oxide layer containing a zirconium oxide is obtained by immersing a Sn-based alloy-plated steel sheet in a solution containing zirconium ions or performing a cathode electrolysis treatment in a solution containing zirconium ions to perform a Sn-based alloy-based galvanized steel sheet. Can be generated on. However, in the dipping treatment, the surface of the Sn-based alloy-plated steel sheet, which is the base, is etched to form a zirconium oxide layer containing a zirconium oxide, so that the amount of adhesion tends to be non-uniform. Since the processing time is long, it is disadvantageous for industrial production. On the other hand, in the cathode electrolysis treatment, a uniform film can be obtained in combination with the forced charge transfer, the surface cleaning by hydrogen generation at the steel sheet interface, and the adhesion promoting effect by increasing the pH. Further, in this cathode electrolysis treatment, the coexistence of nitrate ions and ammonium ions in the treatment liquid enables short-time treatment of about several seconds to several tens of seconds, which is extremely advantageous industrially. Therefore, it is preferable to use the method by cathode electrolysis for forming the zirconium oxide layer containing the zirconium oxide according to the present embodiment.

The concentration of zirconium ions in the solution to be subjected to the cathode electrolysis treatment may be appropriately adjusted according to the production equipment and the production rate (capacity), but for example, the zirconium ion concentration is preferably 100 ppm or more and 4000 ppm or less. Further, there is no problem even if other components such as fluorine ion, ammonium ion, nitrate ion and sulfate ion are contained in the solution containing zirconium ion.

Here, the liquid temperature of the solution for cathodic electrolysis (cathode electrolytic solution) is not particularly specified, but is preferably in the range of, for example, 10 ° C. or higher and 50 ° C. or lower. Cathodic electrolysis at 50 ° C. or lower enables the formation of a dense and uniform film structure formed by very fine particles. Further, by setting the liquid temperature to 50 ° C. or lower, it is possible to prevent the occurrence of defects, cracks, microcracks and the like in the generated zirconium oxide film structure, and to prevent deterioration of the coating film adhesion. Further, when the liquid temperature is 10 ° C. or higher, the film formation efficiency can be made good, and cooling of the solution can be unnecessary even when the outside air temperature is high such as in summer. , Economical.

The pH of the cathode electrolyte is not particularly specified, but is preferably 3 or more and 5 or less. When the pH is 3 or more, the production efficiency of zirconium oxide can be made excellent, and when the pH is 5 or less, a large amount of precipitation is prevented from being generated in the solution, and continuous productivity is improved. Can be good.

In addition, for example, nitric acid, aqueous ammonia, or the like may be added to the cathode electrolytic solution in order to adjust the pH of the cathode electrolytic solution or increase the electrolytic efficiency.

Further, the current density at the time of cathode electrolysis ^{is preferably, for example, 0.05 A / dm 2} or more and 50 A / dm ² or less. When the current density is 0.05 A / dm ² or more, the production efficiency of zirconium oxide can be sufficiently increased, a stable film layer containing zirconium oxide can be produced, and sulfurization resistance can be generated. It can be made sufficiently excellent in blackening resistance, yellowing resistance, and corrosion resistance after painting. When the current density is 50 A / dm ² or less, the production efficiency of zirconium oxide can be made appropriate, and the production of coarse and inferior zirconium oxide can be suppressed. A more preferable range of current densities is 1 A / dm ² or more and 10 A / dm ² or less.

When forming the zirconium oxide layer, the time for cathode electrolysis does not matter. The time of cathode electrolysis may be appropriately adjusted according to the current density with respect to the target amount of Zr adhered.

As the solvent of the solution used for cathode electrolysis, for example, distilled water or the like can be used, but it is not specified in water such as distilled water and is appropriately selected depending on the material to be dissolved, the production method and the like. It is possible to do.

Zirconium in the cathodic electrolysis may be used, for example, zirconium complexes such as H ₂ ZrF ₆ as a source of zirconium. ^{Zr in the Zr complex as described above becomes Zr 4+} due to an increase in pH at the cathode electrode interface and exists in the cathode electrolytic solution. Such Zr ions further react in the cathode electrolyte to form a zirconium oxide. When phosphoric acid is contained in the electrolytic solution, zirconium phosphate may be produced.

Further, as the energization pattern at the time of cathode electrolysis, there is no problem whether it is continuous energization or intermittent energization.

At the time of cathodic electrolysis, the relative flow velocity between the solution used for cathodic electrolysis and the steel sheet is preferably 50 m / min or more. When the relative flow velocity is 50 mp or more, the pH of the steel sheet surface due to hydrogen generation during energization can be easily made uniform, and the formation of coarse zirconium oxide can be suppressed. The upper limit of the relative flow velocity is not particularly specified.

[2.4 Anode electrolysis treatment]
The film layer containing a zirconium oxide according to the present embodiment can be obtained by subjecting a Sn-based alloy-plated steel sheet having the above-mentioned zirconium oxide-containing zirconium oxide layer to an anodic electrolysis treatment in an electrolyte solution. .. In addition to the above-mentioned zirconium oxide, tin oxide is usually produced at the same time by such anodic electrolysis treatment. The electrolyte solution used is not particularly specified for specific components, but it is preferable that the electrolyte solution is a weakly acidic to alkaline electrolyte solution. The neutral to alkaline electrolyte referred to here means a treatment liquid having a pH of 3 or more and 14 or less. When the pH is in this range, the composite plating layer is slowly dissolved in the electrolyte solution, so that the film layer containing the stable tin oxide according to the present embodiment can be stably formed.

Examples of the electrolyte solution (treatment solution) for the above anode electrolysis include hydroxides, carbonates, phosphates, organic acid salts, borates, sulfates, etc. of alkaline and alkaline earth metals. It can be made, for example, sodium carbonate, sodium hydrogen carbonate, sodium diphosphate, trisodium citrate, ammonium monotartrate, sodium sulfate and the like. The concentration of these components is not particularly specified, and it is preferable that the concentration satisfies 0.1 S / m or more as the electrical conductivity. The upper limit of the concentration is not particularly specified, but if the concentration is too high, it may precipitate during storage and cause troubles such as clogging of pipes. Therefore, it is preferable that the solubility of each electrolyte at 0 ° C. or less. The concentration of the above component is preferably a concentration satisfying 0.5 S / m or more and 4 S / m or less in electrical conductivity, and more preferably a concentration satisfying 1 S / m or more and 2.5 S / m or less in electrical conductivity. Is. The electrical conductivity may be measured using a commercially available electrical conductivity meter, and for example, an electrical conductivity cell CT-27112B manufactured by DKK-TOA CORPORATION can be used.

Electric quantity of the anodic electrolysis treatment is preferably 0.1 C / dm ² or more 6.4C / dm ² or less. When the amount of electricity is 0.1 C / dm ² or more, the amount of electricity can be set to a sufficient amount, and the film layer containing the zirconium oxide according to the present embodiment can be stably obtained. When the amount of electricity is 6.4 C / dm ² or less, it is possible to prevent an excessive increase in tin oxide and prevent the appearance from becoming yellowish. A more preferred range, 0.2 C / dm ² or more 3.2C / dm ² or less, even more preferred range is 0.4C / dm ² or more 2.0 C / dm ² or less.

The liquid temperature of the solution for anodic electrolysis is not particularly specified, but is preferably in the range of 5 ° C. or higher and 60 ° C. or lower, and more preferably in the range of 15 ° C. or higher and 50 ° C. or lower. When the temperature is sufficiently high, the electrolysis efficiency can be made sufficient, and the zirconium oxide and tin oxide according to the present embodiment can be easily produced. On the other hand, by setting the temperature to the above upper limit value or less, evaporation of the solution can be prevented and workability and operational stability can be improved.

The current density during anodic electrolysis is not particularly specified, but is preferably in the range of ^{0.2 A / dm 2} or more and 10 A / dm ^{2 or less, for example.} When the current density is 0.2 A / dm ² or more and 10 A / dm ² or less, the stable tin oxide according to the present embodiment can be uniformly and stably produced. Specifically, when the current density is 0.2 A / dm ² or more, the electrolytic treatment time can be relatively shortened, and the deterioration of the corrosion resistance after coating due to the dissolution of the composite plating layer can be prevented. it can. On the other hand, when the current density is 10 A / dm ² or less, hydrogen generation on the Sn-based alloy-plated steel sheet can be suppressed and dissolution of the Sn-plated layer due to an increase in pH can be prevented, which is preferable in terms of production efficiency. , Sufficient black sulphurization resistance and yellowing resistance can be achieved by producing uniform tin oxide. The preferred current density range is 1.0 A / dm ² or more and 5 A / dm ² or less.

The time for anodic electrolysis is not specified. It can be arbitrarily determined according to the current density, the electrode length, and the production speed (plate passing speed).

As the solvent of the solution used for anodic electrolysis, for example, distilled water or the like can be used, but the solvent is not limited to water such as distilled water. Further, as the energization pattern at the time of anodic electrolysis, there is no problem whether it is continuous energization or intermittent energization.

The Sn-based alloy-plated steel sheet and the method for producing the same according to the present invention will be specifically described with reference to Examples and Comparative Examples. The examples shown below are merely examples of the Sn-based alloy-plated steel sheet and its manufacturing method according to the present invention, and the Sn-based alloy-plated steel sheet and its manufacturing method according to the present invention are limited to the following examples. It's not a thing.

<Test material>
A low-carbon cold-rolled steel sheet having a plate thickness of 0.2 mm was subjected to electrolytic alkali degreasing, water washing, dilute sulfuric acid immersion pickling, and water washing as pretreatment, and then Ni-plated in a sulfuric acid bath. The amount of Ni adhered was in the range of ^{1 mg / m 2} or more and 300 mg / m ² or less per side in terms of Ni conversion amount. Further, on the Ni plating, electric Sn plating was performed using a phenol sulfonic acid bath. The amount of Sn adhered was in the range of ^{0.08 g / m 2} or more and 15 g / m ² or less per side in terms of Sn conversion amount. The steel sheet having the Ni-plated layer and the Sn-plated layer thus produced was heat-melted to produce a Sn-based alloy-plated steel sheet in which the composite plating layer was formed. The amount of Ni and Sn adhered to the composite plating layer was determined by immersing the steel sheet after forming the composite plating layer in 10% nitric acid to dissolve the composite plating layer containing Ni and Sn, and in the obtained solution. Ni and Sn were identified by obtaining them by the ICP emission analysis method (ZSX Primus manufactured by Rigaku Co., Ltd.).

The Sn-based alloy-plated steel sheet produced as described above was cathodically electrolyzed in an aqueous solution containing zirconium fluoride to form a zirconium oxide layer on the Sn-based alloy-plated steel sheet. The current density, flow velocity, pH, and bath temperature were changed as appropriate. The amount of Zr adhered was specified by measuring by a fluorescent X-ray method (ZSX Primus manufactured by Rigaku Co., Ltd.).

Further, the Sn-based alloy-plated steel sheet on which the zirconium oxide layer was formed was electrolyzed in a sodium hydrogen carbonate solution having an electric conductivity of 2.0 S / m to form a film layer. The bath temperature was 25 ° C., and the current density of anodic electrolysis was 2 A / dm ² . At some levels, the type of anodic electrolyte and the anodic electrolysis conditions were changed. The anodic electrolysis time was adjusted as appropriate. The pH of the anodic electrolysis treatment liquid is measured with a glass electrode, and the case where the liquid property is weakly acidic to alkaline (pH is included in the range of 3 to 14) is marked with ◯, and the liquid property is acidic. The case (pH is less than 3) is marked with Δ. For comparison, a test material in which only zirconium oxide was produced and anodic electrolysis was not performed was also produced.

The amount of electricity required to reduce the tin oxide of the Sn-based alloy-plated steel sheet thus produced is 0.06 mA / L in a 0.001 mol / L hydrobromic acid aqueous solution from which dissolved oxygen has been removed by bubbling nitrogen gas or the like. It was determined from the product of the time and current for cathodic electrolysis of the Sn-based alloy-plated steel sheet of the present invention with a constant current of ^{cm 2 to reduce and remove tin oxide.}

The Sn-based alloy-plated steel sheet produced as described above was evaluated in various ways as shown below.

[Adhesion amount]
The amount of Zr adhered per side was determined by a fluorescent X-ray method (ZSX Primus manufactured by Rigaku Co., Ltd.).

[Peak position in XPS]
The peak position of the binding energy of Zr3d5 / 2 was investigated by XPS (PHI Quantera SXM manufactured by ULVAC-PHI). In determining the peak position, the binding energy position of Zr3d5 / 2 was determined after shifting the entire spectrum so that the peak position of carbon (C1s) detected on the surface of the sample was 284.8 eV.

[Yellow denaturation resistance]
A wet test was conducted in which the Sn-based alloy-plated steel sheet produced by the method described in the above <test material> was placed in a constant temperature and humidity chamber maintained at 40 ° C. and a relative humidity of 80% for 4 weeks, and the color difference before and after the wet test was performed. The amount of change in the b * value Δb * was obtained and evaluated. If Δb * is 1 or less, it is evaluated as ◎, if it exceeds 1 and 2 or less, it is evaluated as ○, if it exceeds 2 and 3 or less, it is evaluated as △, and if it exceeds 3, it is evaluated as ×, and evaluations “◎” and “○”. , "△" was accepted. Further, even if the value of Δb * is 2 or less, if the b * value before the wet test (initial) is 4 or more, it is set as “Δ”. b * is measured using a commercially available color difference meter SC-GV5 manufactured by Suga Test Instruments Co., Ltd., and the measurement conditions for b * are a light source C, total reflection, and a measurement diameter of 30 mm.

[Coating film adhesion]
The coating film adhesion was evaluated as follows.
After a wet test of a Sn-based alloy-plated steel sheet produced by the method described in the above <test material> by the method described in [Yellow Degeneration], a commercially available epoxy resin paint for cans is applied to the surface in a dry mass of 7 g / g. m ² was coated, baked 10 minutes at 200 ° C., was placed in room temperature for 24 hours. Then, the obtained Sn-based alloy-plated steel sheet was evaluated by making scratches reaching the surface of the steel sheet in a grid pattern (7 scratches in each of the vertical and horizontal directions at 3 mm intervals) and performing a tape peeling test at that portion. If the coating film (test surface) on the grid of the tape application site is not peeled off at all, ◎, if 10% or less of the coating film on the test surface is peeled off, ○, more than 10% and 20% or less of the test surface If the coating film of No. 1 was peeled off, it was evaluated as Δ, and if the coating film of more than 20% of the test surface was peeled off, it was evaluated as ×, and the evaluations “⊚”, “◯”, and “Δ” were passed.

[Sulfide-resistant black denaturation]
Sulfide blackening resistance was evaluated as follows.
A commercially available epoxy resin paint for cans is applied to the surface of a Sn-based alloy-plated steel sheet prepared and wet-tested by the method described in the above [Coating film adhesion] at a dry mass of 7 g / m ² and then at 200 ° C. for 10 minutes. It was baked and left at room temperature for 24 hours. Then, the obtained Sn-based alloy plated steel sheet was cut into a predetermined size, and sodium dihydrogen phosphate was 0.3%, sodium hydrogen phosphate was 0.7%, and L-cysteine hydrochloride was 0.6%. It was immersed in the aqueous solution of the above-mentioned product, retorted at 121 ° C. for 60 minutes in a sealed container, and evaluated from the appearance after the test.
If no change in appearance is observed before and after the test, it is marked as ◎, if a slight blackening is observed (5% or less of the test surface), ○, and a blackening is observed in the region of more than 5% and 10% or less of the test. If so, it was evaluated as Δ, and if blackening was observed in the area exceeding 10% of the test surface, it was evaluated as ×, and the evaluations “◎”, “○”, and “Δ” were passed.

[Corrosion resistance after painting]
Corrosion resistance after painting was evaluated as follows.
A commercially available epoxy resin paint for cans is applied to the surface of a Sn-based alloy-plated steel sheet prepared and wet-tested by the method described in the above [Coating film adhesion] at a dry mass of 7 g / m ² and then at 200 ° C. for 10 minutes. It was baked and left at room temperature for 24 hours. Then, the obtained Sn-based alloy-plated steel sheet was cut into a predetermined size and immersed in commercially available tomato juice at 60 ° C. for 7 days, and then the presence or absence of rust was visually evaluated. If no rust is found, it is rated as "◎", if rust is found in an area of 5% or less of the test surface, it is rated as "○", and if rust is found in a region of more than 5% of the test surface, it is rated as "x". ◎ ”and“ ○ ”are accepted.

<Example 1>
Tables 1 and 2 show the results when the Ni plating adhesion amount, the Sn plating adhesion amount, the zirconium oxide adhesion amount, the Zr3d5 / 2 binding energy position of the zirconium oxide, and the tin oxide amount were changed.

As is clear from Tables 1 and 2 above, A1 to A25, which are the scope of the present invention, have good performance. On the other hand, it can be seen that a1 to a4, which are comparative examples, are inferior in any of sulfurization blackening resistance, yellowing resistance, coating film adhesion, and post-coating corrosion resistance.

<Example 2>
Table 3 shows the results when the amount of electricity required for reduction of tin oxide is different. The performances of Invention Examples B1 to B18 produced according to the conditions specified in the present invention are all good.

<Example 3>
Table 4 shows the results when the amount of electricity of the anode electrolysis was changed in various ways. The conditions for cathode electrolysis were a zirconium ion concentration in an aqueous solution containing zirconium fluoride of 1400 ppm, a current density of 3.0 A / m ² , a flow velocity of 200 m / min, a pH of 4.0, and a bath temperature of 35 ° C. .. Sodium hydrogen carbonate was used as the electrolyte used in the anodic electrolysis treatment liquid, the electrical conductivity was 2.0 S / m, and the bath temperature was 25 ° C.

The performances of Invention Examples C1 to C20 produced according to the conditions specified in the present invention are good. On the other hand, Comparative Examples c1 to c3 are cases that do not meet the conditions specified in the present invention, and it can be seen that any of sulfurization-resistant blackening resistance, yellowing resistance, and coating film adhesion is inferior.

<Example 4>
Table 5 shows the results when the pH of the bath was changed by using various electrolytes as the treatment liquid used for anodic electrolysis. The amount of Ni adhered to one side of Ni plating was 25 mg / m ² , and the amount of Sn adhered to one side of Sn plating was 1.0 g / m ² . The conditions for cathode electrolysis are a current density of 3.0 A / m ² , a flow velocity of 200 m / min, a pH of 4.0, a bath temperature of 35 ° C, and an energization amount of 1.6 C / dm ² during anode electrolysis. The bath temperature was 25 ° C.
The performances of Invention Examples D1 to D14 produced according to the conditions specified in the present invention are all good.

<Example 5>
Table 6 shows the results when the electrical conductivity, bath temperature, and current density of the anodic electrolysis of the treatment liquid used for the anodic electrolysis were variously changed. The amount of Ni adhered to one side of Ni plating was 25 mg / m ² , and the amount of Sn adhered to one side of Sn plating was 1.0 g / m ² . Sodium hydrogen carbonate was used as the electrolyte for anodic electrolysis. The conditions for cathode electrolysis were a zirconium ion concentration in an aqueous solution containing zirconium fluoride of 1400 ppm, a current density of 3.0 A / m ² , a flow velocity of 200 m / min, a pH of 4.0, and a bath temperature of 35 ° C. ..
The performances of Invention Examples E1 to E19 produced according to the conditions specified in the present invention are all good.

Tables 7 to 10 show the results when the cathode electrolysis conditions are variously changed. Tables 7 and 8 show manufacturing conditions such as cathode electrolysis conditions, and Tables 9 and 10 show the physical properties of the obtained Sn-based alloy-plated steel sheet. The amount of Ni adhered to one side of Ni plating was 25 mg / m ² , and the amount of Sn adhered to one side of Sn plating was 1.0 g / m ² . For some samples, the amount of Ni and Sn adhered was increased or decreased.
The performances of Invention Examples F1 to F34 produced according to the conditions specified in the present invention are all good.

As described above, the steel plate, the composite plating layer having the Fe—Ni—Sn alloy layer located on at least one surface of the steel plate and the island-shaped Sn located on the Fe—Ni—Sn alloy layer, and the composite plating. It is located on the layer and has a coating layer containing a tin oxide oxide, and the amount of the zinc oxide adhered in the coating layer is 0.2 mg / m ² or more and 50 mg / m ² or less in terms of the amount of metal Zr. A Sn-based alloy-plated steel sheet containing a zirconium oxide in which the coating layer contains a zirconium oxide in which the peak position of the binding energy of Zr3d5 / 2 by XPS is 182.5 eV or more and 182.9 eV or less does not require conventional chromate treatment. In addition, because it has excellent yellowing resistance, coating adhesion, and blackening resistance to sulfide, it can be widely used as an environment-friendly material for cans, such as food cans and beverage cans, and has extremely high industrial utility value. Is.

Claims (5)

Steel plate and
A composite plating layer having a Fe—Ni—Sn alloy layer located on at least one surface of the steel sheet and island-shaped Sn located on the Fe—Ni—Sn alloy layer, and
And the film layer located in the composite plating layer, containing zirconium oxide and tin oxide,
Have,
The amount of the zirconium oxide adhered to the film layer is 0.2 mg / m ² or more and 50 mg / m ² or less in terms of the amount of metal Zr.
The film layer contains a zirconium oxide having a peak position of the binding energy of Zr3d5 / 2 by X-ray photoelectron spectroscopy of 182.5 eV or more and 182.9 eV or less.
Sn-based alloy plated steel sheet. The Sn-based alloy-plated steel sheet according to claim 1 , wherein the amount of electricity required for the reduction of the tin oxide is 0.2 mC / cm ² or more and 5.0 mC / cm ² or less. The composite plating layer, by mass%, contains a 2 mg / ^{m 2} or more 200 mg / ^{m 2} or less of Ni as Ni equivalent amount, and 10 g / ^{m 2} or less of Sn 0.1 g / ^{m 2} or more as Sn in terms of weight, the The Sn-based alloy-plated steel sheet according to claim 1 or 2. An Fe-Ni-Sn alloy layer containing Ni and Sn on at least one surface of the steel plate and alloying a part or all of Ni and a part of Sn by a melt heat treatment, and the Fe-Ni-Sn. An island-shaped Sn located on the alloy layer and a Sn-based alloy-plated steel plate having a composite plating layer on which tin is formed are immersed in a solution containing zirconium ions or subjected to cathode electrolysis treatment in a solution containing zirconium ions. , A tin oxide oxide is generated on the composite plating layer,
The Sn-based alloy-plated steel sheet was subjected to anodic electrolysis treatment in an electrolyte solution.
A method for producing a Sn-based alloy-plated steel sheet, wherein the amount of electricity in the anodic electrolysis treatment is 0.1 / dm ² or more and 6.4 C / dm ^{2 or less.} The method for producing a Sn-based alloy-plated steel sheet according to claim 4 , wherein the anodic electrolysis treatment is carried out in the electrolyte solution having a pH of 3 or more and 14 or less.