JP6855833B2 - Manufacturing method of Sn-plated steel sheet and Sn-plated steel sheet - Google Patents

Description

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

Tin (Sn) plated steel sheets are well known as "tinplates" and are widely used for cans such as beverage cans and food cans. This is because Sn is a beautiful metal that is safe for the human body. This Sn-plated steel sheet is mainly manufactured by an electroplating method. This is because the electroplating method is more advantageous than the hot-dip plating method in order to control the amount of Sn, which is a relatively expensive metal, to the minimum necessary amount. The Sn-plated steel plate is Sn-plated by a chromate treatment such as an electrolytic treatment or a dipping treatment using a hexavalent chromium salt solution after plating or heat-melting treatment after plating to give a beautiful metallic luster. A chromate film is often applied on top. 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 that the final product does not contain hexavalent chromium and that the chromate treatment itself is not performed. However, as described above, the Sn-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.

Therefore, some Sn-plated steel sheets that have been subjected to a film treatment 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 Sn-plated steel sheets and the manufacturing methods thereof proposed in Patent Documents 1 to 5 are insufficient in blackening resistance to sulfide, 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 to further improve by blackening resistance, yellowing resistance, and coating adhesion without performing conventional chromate treatment. It is an object of the present invention to provide an excellent Sn-plated steel sheet and a method for producing a Sn-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 the Sn-plated steel sheet, sulfide blackening resistance and resistance to sulfide blackening and resistance to blackening without chromate treatment are performed. It has been found that a Sn-plated steel sheet having further excellent yellowing 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
The Sn plating layer located on at least one side of the steel sheet and
A film layer located on the Sn plating layer and containing a zirconium oxide and a 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 is further Sn-plated containing a zirconium oxide having a Zr3d5 / 2 binding energy peak position of 182.5 eV or more and 182.9 eV or less by XPS (X-ray Photoelectron Spectroscopy). Steel plate .
(2 ) The Sn-plated steel sheet according to (1 ), wherein the amount of electricity required for reduction of the tin oxide is 1.0 mC / cm ² or more and 5.0 mC / cm ² or less.
( 3 ) The Sn-plated steel sheet according to (1) or (2) , wherein the Sn-plated layer ^{contains 0.1 g / m 2} or more and 15 g / m ^{2 or less of Sn in mass%.}
( 4 ) A Sn-plated steel plate having a Sn-plated layer on at least one side of the steel plate is immersed in a solution containing zirconium ions or subjected to a cathode electrolysis treatment in a solution containing zirconium ions to form a zirconium oxide on the Sn-plated layer. To generate
The Sn-plated steel sheet was subjected to anodic electrolysis treatment in an electrolyte solution.
Said electrical quantity of anodic electrolysis is 0.1 C / dm ² or more 6.4C / dm ² or less, the production method of the Sn plated steel sheet.
( 5 ) The method for producing a Sn-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, there is provided a method for producing a Sn-plated steel sheet and a Sn-plated steel sheet, which are more excellent in sulfide blackening resistance, yellowing resistance, and coating adhesion, without performing conventional chromate treatment. Is possible.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The present invention described below relates to a Sn-plated steel sheet widely used for cans such as food cans and beverage cans, and a method for producing such a Sn-plated steel sheet. More specifically, the present invention relates to a method for producing a Sn-plated steel sheet and a Sn-plated steel sheet, which are more excellent in sulfurization-resistant blackening resistance, yellowing resistance, and coating adhesion without performing conventional chromate treatment.

<1. Sn plated steel sheet>
The Sn-plated steel sheet according to the present embodiment has a coating layer containing a predetermined amount of zirconium oxide on the surface of the Sn-plated steel sheet in which the Sn-plated layer is formed on at least one surface of the steel sheet.

More specifically, the Sn-plated steel sheet according to the present embodiment has a Sn-plated layer located on at least one side of the steel sheet and a film layer containing a zirconium oxide located on the Sn-plated layer. In the Sn-plated steel plate according to the present embodiment, the amount of 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, and XPS (X-ray Photoelectron Spectroscopy: X). It contains a zirconium oxide having a peak position of the binding energy of Zr3d5 / 2 (X-ray photoelectron spectroscopy) of 182.5 eV or more and 182.9 eV or less.

(1.1 Steel plate)
The steel sheet used as the base material for the Sn-plated steel sheet according to the present embodiment is not particularly specified, and any steel sheet used for the Sn-plated steel sheet for general containers can be used. For example, low carbon steel and ultra-low carbon steel can be mentioned.

(1.2 Sn plating layer)
Sn plating is applied to at least one surface of the steel sheet as described above to form a Sn plating layer. The corrosion resistance of the steel sheet is improved by such Sn plating. The term "Sn plating" as used herein includes not only plating with metal Sn, but also those in which impurities are mixed in metal Sn and those in which trace elements are added to metal Sn.

In the Sn plating layer according to the present embodiment, the amount of Sn adhered to one side is not particularly limited, but for example, the amount of metal Sn is 0.1 g / m ² or more and 15 g / m ² or less, preferably 1.0 g / m ^2. It can be 10 g / m ^{2 or less.} When the amount of adhesion of the Sn plating layer per side is 0.1 g / m ² or more in terms of Sn, the corrosion resistance can be sufficiently excellent. Further, when the amount of adhesion of the Sn plating layer per side is 15 g / m ² or less in terms of Sn, it is possible to sufficiently obtain the effect of improving the corrosion resistance by Sn while suppressing the decrease in adhesion and the increase in cost. it can.

Here, the amount of Sn adhered to one side thereof is, for example, a value measured by the electrolytic method or the fluorescent X-ray method described in JIS G 3303.

Further, the Sn plating layer described above is not limited to the above-described embodiment, and for example, a Fe-Sn alloy layer made of a Fe-Sn alloy, a tin layer formed on the Fe-Sn alloy layer, and the like. It may be composed of. In this case, the ratio of the thicknesses of the tin layer and the Fe—Sn alloy layer is not particularly limited, and it is sufficient that the adhesion amount as the above-mentioned metal Sn amount is secured in the entire Sn plating layer.

(1.3 film layer containing zirconium oxide)
The Sn-plated steel sheet according to the present embodiment has a film layer containing a zirconium oxide on the surface of the Sn-plated steel sheet having the Sn-plated layer as described above. As described above, the amount of zirconium oxide adhered to 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, and the film layer is Zr3d5 / 2 by XPS. Contains a zirconium oxide having a peak position of binding energy of 182.5 eV or more and 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.

By forming the above-mentioned zirconium oxide on the surface of the Sn-plated steel sheet, the sulfurization-resistant blackening resistance, the yellowing resistance, and the coating film adhesion can be further improved. 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 formed by utilizing the pH increase accompanying hydrogen generation from the Sn-plated surface by cathode electrolysis. This is a method of forming 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 a zirconium oxide deficient in cathode is likely to be formed. 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. In addition, 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 formed 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 blackening, yellowing, and coating adhesion with time can be improved by forming the above on a Sn-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. If the binding energy position is less than 182.5 eV, the stability and barrier properties 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 the Sn-plated steel plate having the film layer according to the present embodiment on the surface in an acidic solution such as hydrofluoric acid and sulfuric acid to dissolve it, and dissolving the obtained solution at a high frequency. It is a value measured by chemical analysis such as 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 1.0 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 adhesion of the coating film. On the other hand, when the amount of electricity required for the reduction of the tin oxide is 1.0 mC / cm ² or more, the sulfurization blackening resistance can be sufficiently excellent.

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 or the like at a constant current of ^{0.06 mA / cm 2.} It can be obtained from the product of the time and current for cathodic electrolysis of the steel plate and reduction and removal of 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-plated steel sheet according to the present embodiment may have a Sn-plated layer and a film layer on at least one surface, and may have only one of the Sn-plated layer and the film layer on the other surface. It may or may not have both a Sn plating layer and a coating layer. Further, the Sn-plated steel sheet may have a Sn-plated layer and a film layer on both sides. Further, the Sn-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-plated steel sheet according to the present embodiment may be manufactured by any method, and for example, it can be manufactured by the Sn-plated steel sheet manufacturing method described below.

<2. Manufacturing method of Sn-plated steel sheet>
Next, a method for manufacturing a Sn-plated steel sheet according to the present embodiment will be described. In the method for producing a Sn-plated steel plate according to the present embodiment, a Sn-plated steel plate having a Sn-plated layer on at least one side of the steel plate is immersed in a solution containing zirconium ions or a cathode electrolysis treatment in a solution containing zirconium ions. A zirconium oxide is generated on the Sn-plated layer, and the Sn-plated steel plate is subjected to anodic electrolysis treatment in an electrolyte solution.
The electrical quantity of the anodic electrolysis treatment is 0.1 C / dm ² or more 6.4C / dm ² or less.
In this embodiment, a steel sheet is prepared prior to the cathode electrolysis treatment, and a Sn plating layer is formed on at least one surface of the steel sheet by Sn plating.

(2.1 Preparation of steel plate)
First, a steel sheet to be a base material of the Sn-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 Sn plating layer)
Next, a Sn plating layer is formed on at least one surface of the steel sheet. The method of applying Sn plating to the surface of the steel sheet is not particularly specified, but for example, a known electroplating method is preferable, and a melting method of plating by immersing the steel sheet in the molten Sn may be used. 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, a heat-melting treatment may be performed in which the Sn-plated steel sheet is heated to 231.9 ° C. or higher, which is the melting point of Sn. By this heat melting treatment, the surface of the Sn-plated steel sheet becomes glossy, and an alloy layer of Sn and Fe is formed between the Sn-plated steel sheet and the steel sheet, and the corrosion resistance is further improved.

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 formed on the Sn-plated layer of the Sn-plated steel sheet.

The zirconium oxide layer containing zirconium oxide is formed on the Sn-plated steel sheet by immersing the Sn-plated steel sheet in a solution containing zirconium ions or performing a cathode electrolysis treatment in a solution containing zirconium ions. be able to. However, in the dipping treatment, the surface of the underlying Sn-plated steel sheet is etched to form a zirconium oxide layer containing a zirconium oxide, so that the amount of adhesion tends to be non-uniform and the treatment time. It is also disadvantageous for industrial production because it becomes long. 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 ion and ammonium ion 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, sulfate ion and phosphate 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 composed of 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 zirconium oxide formation efficiency can be sufficiently increased, a stable film layer containing the zirconium oxide can be formed, and sulfurization resistance can be obtained. Black denaturation and yellow denaturation resistance can be made sufficiently excellent. 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 is also 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 m / min 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 zirconium oxide-containing film layer according to the present embodiment can be obtained by subjecting a Sn-plated steel sheet on which the zirconium oxide-containing zirconium oxide layer is formed 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 weakly acidic 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 Sn plating layer is slowly dissolved in the electrolyte solution, so that the zirconium oxide and tin oxide according to the present embodiment can be stably produced.

Examples of the electrolyte solution (treatment liquid) for the above-mentioned 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 it is 0.1 C / dm ² or more, the amount of electricity can be 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 1.6C / 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 zirconium oxide and 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 Sn 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-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 and is uniform. Sufficient black sulphurization resistance and yellowing resistance can be achieved by producing 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.

Subsequently, the manufacturing method of the Sn-plated steel sheet and the Sn-plated steel sheet 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 manufacturing method of the Sn-plated steel sheet and the Sn-plated steel sheet according to the present invention, and the manufacturing method of the Sn-plated steel sheet and the Sn-plated steel sheet according to the present invention is limited to the following examples. It is not something that is done.

<Test material>
As a pretreatment, a low-carbon cold-rolled steel sheet having a thickness of 0.2 mm is subjected to electrolytic alkali degreasing, water washing, dilute sulfuric acid immersion pickling, water washing, and then electro-Sn plating using a phenol sulfonic acid bath. It was heat-melted. The amount of adhesion of the Sn plating layer was based on about 2.8 g / m ² per side, but for some test materials, the amount of adhesion of the Sn plating layer was changed by changing the energization time. In addition, a test material that is not heat-melted after electro-Sn plating was also produced. The amount of Sn plating adhered was specified by measuring by a fluorescent X-ray method (ZSX Primus manufactured by Rigaku Co., Ltd.).

The Sn-plated steel sheet prepared as described above was cathodically electrolyzed in an aqueous solution containing zirconium fluoride to form a zirconium oxide layer on the Sn-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-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 amount of electricity of anodic electrolysis was set to various values. The bath temperature was 25 ° C., and the amount of electricity of the anode electrolysis was appropriately changed based on ^{1.6 C / dm 2.} At some levels, the type of anodic electrolyte and the anodic electrolysis conditions were changed. The anodic electrolysis time was set to a value according to the amount of electricity and the current density. 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-plated steel sheet thus produced 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 or the like. The Sn-plated steel sheet of the present invention was cathodically electrolyzed with the constant current of the above, and it was obtained from the product of the time and the current for reducing and removing tin oxide.

The Sn-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-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 b * before and after the wet test was performed. The amount of change in value Δb * was obtained and evaluated. If Δb * is 1 or less, it is evaluated as ◎, if it exceeds 1, it is evaluated as ○, if it exceeds 2, it is evaluated as △, 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 6 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.
The Sn-plated steel sheet produced by the method described in the above <test material> is subjected to a wet test by the method described in [Yellow Degeneration], and then a commercially available epoxy resin paint for cans is applied to the surface in a dry mass of 7 g / m ^2. It was applied, baked at 200 ° C. for 10 minutes, and allowed to stand at room temperature for 24 hours. Then, the obtained Sn-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 evaluations “⊚”, “◯”, and “Δ” were passed.

[Sulfide-resistant black denaturation]
Sulfide blackening resistance was evaluated as follows.
A commercially available epoxy resin paint for cans was applied to the surface of a Sn-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 baked at 200 ° C. for 10 minutes. It was allowed to stand at room temperature for 24 hours. Then, the obtained Sn-plated steel sheet is cut into a predetermined size, and an aqueous solution consisting of 0.3% sodium dihydrogen phosphate, 0.7% sodium hydrogen phosphate, and 0.6% L-cysteine hydrochloride is used. It was immersed in and retorted in a sealed container at 121 ° C. for 60 minutes, 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 was applied to the surface of a Sn-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 baked at 200 ° C. for 10 minutes. It was allowed to stand at room temperature for 24 hours. Then, the obtained Sn-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>
Table 1 shows the results when the amount of Sn plating adhered, the amount of zirconium oxide adhered, the binding energy position of Zr3d5 / 2 of zirconium oxide, and the amount of tin oxide were changed.

As is clear from Table 1 above, A1 to A12, which are the scope of the present invention, have good performance. On the other hand, it can be seen that a1 to a5, which are comparative examples, are inferior in any of sulfurization blackening resistance, yellowing resistance, coating film adhesion, and corrosion resistance after coating.

<Example 2>
Table 2 shows the results when the amount of electricity required for reduction of tin oxide is different. The performances of Invention Examples A13 to A27 produced according to the conditions specified in the present invention are all good.

<Example 3>
Table 3 shows the results when the amount of electricity of the anode electrolysis was changed in various ways. After Sn plating, heat melting treatment was also performed. 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 B1 to B14 produced according to the conditions specified in the present invention are good. On the other hand, Comparative Examples b1 to b3 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 4 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 Sn adhered to one side of the Sn plating layer was 2.8 g / m ^2, and heat melting treatment was also performed. 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 C1 to C12 produced according to the conditions specified in the present invention are all good.

<Example 5>
Table 5 shows the results when the electrical conductivity of the treatment liquid used for anodic electrolysis, the bath temperature, and the conditions for anodic electrolysis were variously changed. The amount of Sn adhered to one side of the Sn plating layer was 2.8 g / m ^2, and heat melting treatment was also performed. 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 D1 to D19 produced according to the conditions specified in the present invention are all good.

<Example 6>
Tables 6 to 9 show the results when the cathode electrolysis conditions are variously changed. Tables 6 and 7 show manufacturing conditions such as cathode electrolysis conditions, and Tables 8 and 9 show the physical properties of the obtained Sn-plated steel sheet. The amount of Sn adhered to one side of the Sn plating layer ^{was basically 2.8 g / m 2} , but the amount of Sn adhered to some samples was increased or decreased, and samples not subjected to heat melting treatment were also prepared.

The performances of Invention Examples E1 to E34 produced according to the conditions specified in the present invention are all good.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical idea described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

As described above, it has a steel plate, a Sn plating layer located on at least one side of the steel plate, and a film layer located on the Sn plating layer and containing a zirconium oxide, and the amount of the zirconium oxide adhered is large. The amount of metal Zr is 0.2 mg / m ² or more and 50 mg / m ² or less, the coating layer is XPS (X-ray Photoelectron Spectroscopy: X-ray photoelectron spectroscopy), and the peak position of the binding energy of Zr3d5 / 2 is 182.5 eV. Sn-plated steel sheets containing zirconium oxide of 182.9 eV or less are excellent in sulfide blackening resistance, yellowing resistance, and coating adhesion without the need for conventional chromate treatment, and are therefore suitable for environment-friendly cans. As a material, it can be widely used for food cans, beverage cans, etc., and has extremely high industrial utility value.

Claims (5)

Steel plate and
The Sn plating layer located on at least one side of the steel sheet and
A film layer located on the Sn plating layer and containing a zirconium oxide and a 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 is a Sn-plated steel sheet containing a zirconium oxide having a peak position of Zr3d5 / 2 binding energy of 182.5 eV or more and 182.9 eV or less by X-ray photoelectron spectroscopy. The Sn-plated steel sheet according to claim 1 , wherein the amount of electricity required for reduction of the tin oxide is 1.0 mC / cm ² or more and 5.0 mC / cm ² or less. The Sn-plated steel sheet according to claim 1 or 2 , wherein the Sn-plated layer contains Sn in an amount of 0.1 g / m ² or more and 15 g / m ^{2 or less in mass%.} A Sn-plated steel plate having a Sn-plated layer on at least one side of the steel plate is immersed in a solution containing zirconium ions or subjected to a cathode electrolysis treatment in a solution containing zirconium ions to generate a zirconium oxide on the Sn-plated layer. ,
The Sn-plated steel sheet was subjected to anodic electrolysis treatment in an electrolyte solution.
Said electrical quantity of anodic electrolysis is 0.1 C / dm ² or more 6.4C / dm ² or less, the production method of the Sn plated steel sheet. The method for producing a Sn-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.