0001]The present invention relates to a method for producing a Sn-plated steel sheet and Sn-plated steel sheet.
　This application, on April 13, 2017, claiming priority on Japanese Patent Application No. 2017-79792 filed in Japan, the contents of which are incorporated herein.
BACKGROUND
[0002]Tin (Sn) plated steel sheet is better known as "tinplate", the can use other such beverage cans and food cans, it is widely used. This is because Sn is safe to the human body, and a beautiful metallic. The Sn plated steel sheet is mainly produced by electroplating. This is controlled with the amount of necessary minimum amount of Sn is a relatively expensive metal is by electroplating method than hot-dip plating method is preferred. Sn-plated steel sheet after plating, or, after a beautiful metallic luster imparted by heating and melting treatment after plating, by chromate treatment, such as electrolytic treatment or the immersion treatment using a solution of hexavalent chromate, Sn plating it is often subjected to chromate film thereon. The effect of this chromate film is oxidized yellowing prevention and appearance by suppressing the Sn plated surface, preventing the coating adhesion deterioration by cohesive failure of the tin oxide in the case where used is painted, sulfidation blackening improvements, and the like.
[0003]
　On the other hand, in recent years, from growing awareness of the environment and safety, not only does not contain hexavalent chromium in the final product, it is required not to perform chromate treatment itself. However, Sn-plated steel sheet having no chromate film, as described above, the appearance by the growth of tin oxide yellowing or paint adhesion is lowered. Further, it decreases the sulfidation blackening.
　Therefore, Sn-plated steel sheet in which the coating process to replace the chromate film have been proposed.
[0004]
　For example, Patent Document 1, by treatment with a solution containing a phosphoric acid ion and a silane coupling agent, Sn-plated steel sheet has been proposed to form a film containing P and Si. In Patent Document 2, by treatment with a solution containing aluminum phosphate, Al and P, Ni, Co, and at least one of Cu, Sn plating to form a coating comprising the reaction product of a silane coupling agent steel plate has been proposed.
　In Patent Document 3, heat treatment is performed until the Zn alone plated layer disappears after the Zn plated on Sn plating method of the Sn-plated steel sheet having no chromate film have been proposed. Patent Document 4 and Patent Document 5, a zirconium phosphate, a container for steel sheet having a chemical conversion film containing phenol resin have been proposed.
CITATION
Patent Document
[0005]
Patent Document 1: Japanese Patent 2004-60052 JP
Patent Document 2: Japanese Patent 2011-174172 JP
Patent Document 3: Japanese Sho 63-290292 Patent Publication
Patent Document 4: Japanese Patent 2007- 284789 JP
Patent Document 5: Japanese Patent 2010-13728 JP
Summary of the Invention
Problems that the Invention is to Solve
[0006]
　For Sn-plated steel sheet produced, then, although such sterilization and paint baking before filling the contents after can manufacturing is performed, Sn plated steel sheet is heated at that time. However, the Sn plated steel sheet and a manufacturing method proposed in Patent Documents 1 to 5, when the Sn plated steel sheet is heated, a portion of the Sn plated steel sheet is disadvantageously discolored.
[0007]
　The present invention has been made in view of the above problems, it is an object of the present invention, without performing conventional chromate treatment, Sn-plated steel sheet and Sn-plated steel sheet excellent in discoloration resistance upon heating to provide a method of manufacturing.
Means for Solving the Problems
[0008]
　In order to solve the above problems, the present inventors have studied intensively, in Sn-plated steel sheet having a coating comprising zirconium oxide on the surface of the Sn plated steel sheet and tin oxide, the depth of the X-ray photoelectron spectroscopy the position of the maximum value of the element concentration of zirconium oxide by way analysis, than the position of the maximum value of the element concentration of Sn which is present as tin oxide, the presence on the surface side of the film, without chromate treatment It found that it is possible to realize a Sn-plated steel sheet excellent in discoloration resistance after heating.
[0009]
　Summary of the completed invention based on the above findings, as follows.
(1) Sn-plated steel sheet according to one embodiment of the present invention includes a steel sheet, a Sn plating layer provided on at least one surface of the steel sheet, provided on a surface of the Sn plating layer, a zirconium oxide and tin oxide and a film containing an object, the content of the zirconium oxide in the coating is, 0.2 mg / m of a metal Zr amount 2 ~ 50 mg / m 2 a, depth analysis by X-ray photoelectron spectroscopy in the zirconium oxide depth position a element concentration is the largest Zr present as is, than element concentration depth position B which is the maximum of Sn which is present as the tin oxide, the surface side of the film located in, and the distance in the depth direction between the depth position a and the depth position B is 0.5nm or more.
[0010]
(2) In the Sn-plated steel sheet according to (1), in the X-ray photoelectron spectroscopy according to the depth direction elemental analysis, the element concentration of Zr present as the zirconium oxide in the depth position A, 20% it may be greater than or equal to.
[0011]
(3) above (1) or the Sn-plated steel sheet according to (2), wherein the coating further comprises a phosphoric acid compound, in the film, the content of the phosphate compound in terms of P content alpha (Unit: mg / m 2 a), the content beta (units of the zirconium oxide in terms of metal Zr content: mg / m 2 ) value alpha / beta divided by may be 0.2 to 2.0.
[0012]
(4) In the Sn-plated steel sheet according to any one aspect of the above (1) to (3), and the depth position of the depth of the thickness of 1/3 position C of the coating from the surface of the film when the depth position a may be located on the surface side of the depth position C.
[0013]
(5) A method of manufacturing a Sn-plated steel sheet according to another aspect of the present invention, with respect to Sn-plated steel sheet Sn plating layer is formed on at least one surface of the steel sheet, cathode electrolysis in a solution containing zirconium ions by performing the process, a step of forming a zirconium oxide on the Sn plating layer, after the cathode electrolytic treatment, and performing a cleaning process by immersion or spraying or 0.3 seconds above 25 ° C. hot water after the cleaning treatment, Zr ion concentration performs an anodic electrolysis treatment in the following in the electrolyte solution 270 ppm, and a step of forming a film containing said zirconium oxide and tin oxide on the Sn plated layer.
[0014]
(6) In the method for manufacturing a Sn-plated steel sheet according to (5), the content of the zirconium oxide in the coating is, 0.2 mg / m of a metal Zr amount 2 ~ 50 mg / m 2 a, X-rays in depth analysis of the film by photoelectron spectroscopy, the zirconium oxide depth position a element concentration of Zr is present the maximum as is the depth element concentration of Sn which is present as the tin oxide is up to than is position B, located on the surface side of the film, and the distance in the depth direction between the depth position a and the depth position B may also be 0.5nm or more.
[0015]
(7) above (5) or in the method for manufacturing a Sn-plated steel sheet according to (6), in the depth direction elemental analysis by X-ray photoelectron spectroscopy, of Zr present as the zirconium oxide in the depth position A element concentration may be 20% or more.
[0016]
(8) (5) In the manufacturing method of the Sn-plated steel sheet according to any one aspect to (7), wherein the coating further comprises a phosphoric acid compound in the coating, the phosphoric acid compound in terms of P content content alpha (unit: mg / m 2 ), said zirconium oxide content beta (unit: mg / m in terms of metal Zr 2 ) the value alpha / beta divided by the, 0.2-2. it may be zero.
The invention's effect
[0017]
　According to the above embodiment, without performing conventional chromate treatment method of the Sn plated steel sheet and Sn-plated steel sheet excellent in discoloration resistance upon heating it becomes possible to provide a.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018]
[1] when performing X-ray photoelectron spectroscopy with respect to the Sn-plated steel sheet according to the present embodiment (XPS), it is a diagram showing the positional relationship between the peak of the tin oxide-zirconium oxide.
[Figure 2] when performing X-ray photoelectron spectroscopy with respect to the Sn-plated steel sheet according to the prior art (XPS), it is a diagram showing the positional relationship between the peak of the tin oxide-zirconium oxide.
In FIG 3] X-ray photoelectron spectroscopy (XPS) in the depth direction analysis, the position indicating the maximum element concentration of zirconium present as zirconium oxide to the film thickness (the depth), the color fastness after heating is a graph showing the relationship.
4 is a schematic view showing a layer structure of the Sn-plated steel sheet according to the present embodiment.
DESCRIPTION OF THE INVENTION
[0019]
　Reference will now be described in detail preferred embodiments of the present invention.
　The present invention described below, food cans, and Sn plated steel sheet is widely used in other cans applications such as beverage cans, to a method of manufacturing such a Sn-plated steel sheet. More specifically, without performing the conventional chromate treatment, a method for manufacturing a Sn-plated steel sheet and Sn-plated steel sheet excellent in discoloration resistance after heating.
[0020]
<1. Sn-plated steel sheet>
　Fig. 4 is a schematic view showing a layer structure of the Sn-plated steel sheet according to the present embodiment. As shown in FIG. 4, Sn-plated steel sheet 100 includes a steel plate 10, and the Sn plating layer 20 provided on at least one surface of the steel plate 10, provided on the surface of the Sn-plated layer 20, zirconium oxide and tin oxide and a coating 30 including the object.
　In the present embodiment, Sn-plated layer 20 and film 30, of the two surfaces of the steel sheet 10, it may be formed on at least one surface.
[0021]
　Coating More specifically, Sn-plated steel sheet 100 according to this embodiment, on the Sn-plated steel sheet Sn plating layer 20 is formed on at least one surface of the steel sheet 10, containing zirconium oxide and tin oxide has 30, the content of zirconium oxide in the film 30, 0.2 mg / m of a metal Zr amount 2 ~ 50 mg / m 2 is further X-ray photoelectron spectroscopy (X-ray photoelectron spectroscopy: XPS) by depth analysis (hereinafter, in also referred to as "XPS depth profiling"), the depth position a element concentration of Zr is present is the maximum as a zirconium oxide, a Sn which is present as tin oxide element concentration than the depth position B is maximum, the depth between the located on the surface side of the film 30, and the depth position a and depth position B Distance of direction is 0.5nm or more.
[0022]
(1.1 steel)
　steel sheet 10 used in the Sn-plated steel sheet 100 according to this embodiment as the base material is not particularly limited. It may be used a steel plate 10 used in the Sn-plated steel sheet of a typical container, and a low carbon steel or ultra-low carbon steel as an example.
[0023]
(1.2 Sn plating layer)
　at least one surface of the steel sheet 10, and Sn-plated, Sn plating layer 20 is formed. By such Sn plating, thereby improving the corrosion resistance of the Sn plated steel sheet 100. Note that the "Sn plating" in this specification includes not only plated with a metal Sn, and that impurities are mixed into the metal Sn, including those trace elements were added to the metal Sn.
[0024]
　In the Sn-plated layer 20 of the present embodiment is not particularly limited Sn coating weight per one side, the metal Sn amount, 0.1 g / m 2 ~ 15 g / m 2 is preferably. Adhesion amount per one side of the Sn-plated layer is 0.1 g / m as Sn equivalent amount 2 when it is above can obtain a suitable corrosion resistance. Further, the adhesion amount per one side of the Sn-plated layer 20 is 15 g / m as Sn in terms of weight 2 is less than or equal to, while suppressing a decrease or increase in cost of the adhesion, to obtain a sufficient effect of improving the corrosion resistance by Sn can.
[0025]
　Here, the adhesion amount of Sn per one surface of the can, for example, to the value measured by the electrolytic method or X-ray fluorescence method described in JIS G 3303.
[0026]
(Film and a 1-3 zirconium oxide and tin oxide)
　Sn-plated steel sheet 100 according to this embodiment, the surface of the Sn-plated layer 20, the film (chemical conversion coating containing zirconium oxide and tin oxide ) with 30.
　As described above, the content of zirconium oxide in the film 30, one surface per 0.2 mg / m of a metal Zr amount 2 ~ 50 mg / m 2 is. In XPS depth profiling, there depth position A element concentration is the largest Zr which is a zirconium oxide, than there is a depth position B element concentration is the largest Sn as tin oxide, film 30 located on the surface side of, and the distance in the depth direction is 0.5nm or more between the depth position a and depth position B (e.g., see FIG. 1).
　Depth direction distance between the depth position A and depth position B is preferably not less than 1.0 nm, more preferably 1.5nm or more.
[0027]
　Coating 30, in XPS depth profiling, the element concentration of tin metal from the surface of the Sn plated steel sheet 100 is defined as a range to a depth position where the 90%. Further, the element concentration in the XPS depth profiling, a concentration when the Sn which is present as tin oxide, the sum of the element concentration of Zr present as Sn and zirconium oxides present as metallic tin to 100% is there.
[0028]
　Sn-plated steel sheet 100 according to this embodiment, by having film 30 comprising zirconium oxide as described above to the surface of the Sn-plated layer 20 and tin oxide, to improve the discoloration resistance upon heating it can. The reason for this is not clear, it is believed to be as follows by a detailed investigation of the inventors of the present invention.
[0029]
　Discoloration due to heating to be applied to the Sn-plated steel sheet during the paint baking or during sterilization is caused by the growth of tin oxide formed by reaction between Sn and oxygen in the Sn-plated layer 20. On the surface of the Sn-plated layer 20, by forming a film 30 comprising zirconium oxide inhibits the diffusion of oxygen into the Sn plating layer 20 surface, formation of tin oxide, is believed grow can be suppressed.
　However, in the Sn-plated steel sheet having a conventional zirconium coating, the XPS depth profiling, the element concentration of Zr present as zirconium oxide is depth position is the maximum, element concentration of Sn which is present as tin oxide there than depth position is the maximum, was present on the inner surface side of the film. That is, tin oxide was present more in the surface side of the zirconium oxide (e.g., see FIG. 2). Therefore, in the conventional Sn-plated steel sheet, a further oxide (SnO from SnO tin oxide 2 ), or tin oxide is grown by oxygen diffusion and reaction of the oxygen deficient part in the tin oxide, discoloration is considered to be brought about.
　On the other hand, as in the present invention, the XPS depth profiling, there depth position A element concentration is the largest Zr which is a zirconium oxide, a depth element concentration of Sn which is present as tin oxide is up to than is position B, located on the surface side of the film 30, and, if the distance in the depth direction between the depth position a and depth position B is 0.5nm or more (e.g., see FIG. 1) the by zirconium oxide, tin oxide growth can be suppressed to oxygen diffusion into the Sn plating layer 20 surface is inhibited.
[0030]
　Further, the present inventors, although located on the surface side of the film 30 than the depth position B depth position A, the distance in the depth direction between the depth position A and depth position B If it is less than 0.5nm, a suitable color fastness was found that not obtained. The reason is not clear, oxygen diffusion inhibiting effect on the Sn-plated layer 20 surface by zirconium oxide is considered to be because insufficient.
[0031]
　To achieve growth inhibiting effect of tin oxide as described above, per side 0.2 mg / m of a metal Zr amount 2 ~ 50 mg / m 2 is necessary zirconium oxide. The content of zirconium oxide is within the range described above, discoloration resistance upon heating, coating adhesion can be ensured sulfidation blackening. A metallic Zr amount 0.2 mg / m 2 if it is less than, not only can not be sufficiently suppressed the growth of tin oxides, inferior sulfidation blackening. The content of zirconium oxide is, 50 mg / m of a metal Zr amount 2 when it exceeds, because the zirconium oxide is excessive, the coating film adhesion is deteriorated, and the corrosion resistance inferior. The content of zirconium oxide, a metal Zr content per surface, preferably 1.0 mg / m 2 ~ 30 mg / m 2 is more preferably 2.0 mg / m 2 ~ 10 mg / m 2 is.
[0032]
　The coating 30 when XPS depth elemental analysis, it is preferable element concentration of Zr in the depth position A is 20% or more. If element concentration of Zr in the depth position A 20 percent or more, the diffusion of oxygen into the Sn plating layer 20 surface can effectively be suppressed. More preferably, element concentration of Zr in the depth position A is 30% or more.
[0033]
　And a thickness of the depth position the depth position C of the third of the film 30 from the surface of the film 30, when the film 30 and XPS depth profiling, the depth position A surface side of the depth position C it is preferred that in. Thus, more effectively suppress the diffusion of oxygen into the Sn plating layer 20 surface.
[0034]
　Film 30 includes a phosphate compound addition, in the coating 30, the content alpha (Unit: mg / m of phosphate compound in terms of P content 2 ) the content of zirconium oxide in terms of metal Zr content β (unit: mg / m 2 ) value alpha / beta divided by is preferably 0.2 to 2.0. Examples of the phosphoric acid compound, for example, tin phosphate, zirconium phosphate and the like.
　By containing the P in the film 30, film 30 containing zirconium oxide, and tin oxide becomes dense, thereby improving the sulfidation blackening and the corrosion resistance after coating. Such phosphoric acid compounds, such as tin phosphate, zirconium phosphate, and metal phosphates. When alpha / beta is greater than 2, the phosphoric acid compound content is excessive, undesirable because the effect of improving sulfide blackening becomes poor. The alpha / beta, more preferably 0.4 to 1.5.
[0035]
　State of presence of zirconium oxide and tin oxide in film 30 may be both mixed state of may be a solid solution of oxides, regardless of its presence state. In addition to zirconium oxide and tin oxide in the coating 30, the zirconium and zirconium metal hydroxide may contain a metal tin. Moreover, inevitable zirconium oxide and tin oxide than single element or a compound of in the film 30, for example as an impurity, no problem be included. For example, the coating 30, C, N, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Co, Ni, may contain elements such as Zn.
[0036]
　Adhesion amount of the Zr and P are the Sn plated steel sheet 100 having a film 30 according to this embodiment on a surface, for example, and dissolved by immersion in an acidic solution such as hydrofluoric acid and sulfuric acid, the resulting solution of inductively coupled plasma (inductively coupled plasma: ICP) and the value measured by chemical analysis such as emission spectroscopy.
[0037]
　Sn-plated steel sheet 100 of the present embodiment may be manufactured by any method, for example, by the production method of the Sn plated steel sheet described below, it can be produced.
[0038]
<2. Manufacturing Method> of the Sn-plated steel sheet
　below, a method for manufacturing the Sn-plated steel sheet 100 having a film 30 comprising zirconium oxide and tin oxide according to the present embodiment will be described.
　Method for manufacturing a Sn-plated steel sheet according to the present embodiment, the Sn-plated steel sheet Sn plating layer 20 is formed on at least one surface of the steel plate 10, by cathodic electrolysis in a solution containing zirconium ions, Sn plated layer a first step of forming a zirconium oxide on 20,
　a second step of performing a cleaning process by immersion or spraying of 0.3 second or more at 25 ° C. or more hot water relative to Sn-plated steel sheet,
　Sn-plated further subjected to anodic electrolysis at a Zr ion concentration following in the electrolyte solution 270ppm against the steel sheet, and a third step of forming a film 30 comprising zirconium oxide and tin oxide on the Sn-plated steel sheet, the .
　In this embodiment, prior to the cathodic electrolytic treatment, as well as prepare the steel sheet 10, to form a Sn plating layer 20 on at least one surface of the steel sheet by Sn plating.
[0039]
(2.1 steel Preparing)
　manufacturing method and material of the steel plate 10 is not particularly limited, for example, hot rolling the casting, pickling, cold rolling, annealing, manufactured through the temper rolling or the like process steel it can be mentioned.
[0040]
(2.2 formation of the Sn-plated layer)
　Next, on at least one surface of the steel plate 10 to form a Sn plating layer 20. Method of applying Sn plating on the steel sheet 10 surface is not particularly limited, for example, preferably a known electroplating method, may be used melt process for plating by immersing the steel plate 10 to the molten Sn. The electroplating method, for example, can be utilized electrolytic method using a known Ferrostan bath or halogen bath or alkali bath.
[0041]
　Incidentally, after the Sn plating, heating the steel sheet 10 which has been subjected to Sn plating 231.9 ° C. or higher, which is the melting point of Sn, it may be subjected to heating and melting treatment. This heating and melting treatment, along with gloss comes into the surface of the Sn plated steel sheet, between the Sn-plated layer 20 and the steel sheet 10, an alloy layer of Sn and Fe (not shown) is formed, because corrosion resistance is further improved preferable.
　In the case of using a steel plate 10 that Sn plating layer 20 is formed in advance, it is possible to omit the above two steps.
[0042]
(2.3 cathodic electrolysis treatment)
　in order to form a film 30 according to this embodiment, first, on the Sn-plated layer 20 of Sn-plated steel sheet, a zirconium oxide layer containing zirconium oxide (not shown) formed is (first step).
[0043]
　Zirconium oxide layer containing zirconium oxide (not shown), by performing the cathode electrolytic treatment with respect to Sn plated steel sheet in a solution containing zirconium ions, can be formed on the Sn-plated steel sheet.
　As a method for forming a zirconium oxide layer (not shown), immersion treatment can be cited in addition to the cathodic electrolysis treatment. However, in the immersion process, the zirconium oxide layer surface of the Sn plated steel sheet is underlying containing zirconium oxide by being etched is formed. Therefore, a zirconium oxide layer (not shown) of the easy adhesion amount becomes uneven, Also, since the processing time becomes longer, the industrial production is disadvantageous.
　On the other hand, at the cathode electrolytic treatment, adhesion-promoting effect by forced charge transfer and surface cleaning and pH increase due to hydrogen generation on the steel sheet surface is also coupled, it is possible to obtain a uniform film. Further, in the cathode electrolytic treatment, by coexistence of the nitrate ions and ammonium ions in the treatment liquid, since it is possible to short-term treatment of several tens of seconds, the industrially very advantageous.
　Therefore, the formation of zirconium oxide layer containing zirconium oxide according to this embodiment (not shown) uses a cathodic electrolysis treatment.
[0044]
　Solution used in the cathode electrolytic treatment (hereinafter, referred to as cathodic electrolytic treatment solution) the concentration of zirconium ions in may be appropriately adjusted according to the production equipment and production rate (capacity), for example, zirconium ion concentration, it is preferable that the 100ppm ~ 4000ppm. Cathodic electrolytic treatment solution, fluorine ions, ammonium ions, nitrate ions, sulfate ion, may contain a phosphoric acid ion.
[0045]
　It is not particularly limited liquid temperature of the cathode electrolytic treatment solution, for example, preferably in the range of 10 ℃ ~ 50 ℃. By performing cathodic electrolysis treatment at 50 ° C. or less, formed by very fine particles, it is possible to form a dense and uniform film structure. On the other hand, by performing cathodic electrolysis at 10 ° C. or higher, thereby improving the formation efficiency of the coating.
[0046]
　The pH of the cathodic electrolytic treatment solution is not particularly limited, it is preferably 3-5. pH is improved generation efficiency of zirconium oxide if 3 or more, pH is difficult to precipitate in the processing liquid as long as 5 or less occurs, preferably to improve the continuous productivity.
[0047]
　In order to improve the adjustment and electrolysis efficiency in the pH of the cathodic electrolytic treatment solution, while the cathode electrolytic treatment solution, such as nitric acid, ammonia water or the like may be added.
[0048]
　The current density at the cathode electrolytic treatment, for example, 0.05 A / dm 2 ~ 50A / dm 2 is preferably set to. Current density is 0.05 A / dm 2 when it is above, the formation efficiency of the zirconium oxide can be sufficiently high, of the coating 30 containing zirconium oxide defined in the present invention and a tin oxide it can be formed more reliably. Current density is 50A / dm 2 when it is less, it is possible to prevent the formation efficiency is too large zirconium oxide, zirconium oxide less coarse and adhesion is formed. More preferred current density range of, 1A / dm 2 ~ 10A / dm 2 is.
[0049]
　In forming the zirconium oxide layer (not shown), the time of the cathode electrolytic treatment is not particularly limited, it may be suitably adjusted so as to obtain a desired Zr coating weight.
[0050]
　The solvent used for the cathode electrolytic treatment solution, e.g., distilled water can be used, but the present invention is defined in the water, such as distilled water, depending on the forming method and the like of the compound or coating 30 that dissolves It can be appropriately selected.
[0051]
　Sources of zirconium, for example, H 2 ZrF 6 can be used zirconium complexes such as. Zr in Zr complexes, Zr by increase in pH at the cathode electrode interface 4+ present in the cathode electrolytic treatment solution becomes. Such Zr ions further react with the cathode electrolytic treatment solution, a zirconium oxide. If it contains phosphoric acid in the cathode electrolytic treatment solution, zirconium phosphate is also formed.
[0052]
　Energization pattern during cathodic electrolysis treatment may be intermittent energization may be continuous energization.
[0053]
　The relative flow rate of the cathode electrolytic treatment solution and the steel sheet 10 at the time of the cathode electrolytic treatment, it is preferable that the 50 m / min or more. If the relative flow rate of 50 m / min or more, it is easy to uniform the pH of the steel sheet 10 surface due to hydrogen generation during energization, it is possible to suppress the formation of coarse zirconium oxide. The upper limit of the relative velocity is not particularly limited.
[0054]
(2.4 cleaning process)
　in order to form a film 30 according to this embodiment, on the Sn-plated layer 20 of Sn-plated steel sheet, forming a zirconium oxide layer containing the zirconium oxide (not shown) after, for cleaning treatment by immersion or spraying of 0.3 seconds or more 25 ° C. warm water (second step).
　Oxide or hydroxide of tin inevitably present on the surface of the zirconium oxide layer after the cathode electrolytic treatment (not shown) by the cleaning process, reducing the metal tin, combined with further subsequent anodic electrolysis treatment, these oxide or hydroxide of tin surface, metallic tin effectively it can be removed.
[0055]
　Temperature of hot water used in the washing treatment is 25 ° C. or higher. If the temperature of the hot water is lower than 25 ° C., it is impossible to sufficiently reduce the zirconium oxide layer oxide or hydroxide of tin inevitably present on the surface (not shown), the metal tin. Therefore, even if the anodic electrolysis treatment after washing treatment, it is difficult to obtain a discoloration resistance upon suitable heating.
　Hot water temperature is preferably less than 30 ° C. or higher 40 ° C., preferably for thereby can effectively remove oxides or hydroxides of tin.
[0056]
　Time of the cleaning process, is greater than or equal to 0.3 seconds. If the time of the cleaning process is less than 0.3 seconds, it is impossible to reduce the oxide or hydroxide of tin effectively, undesirable. Time of washing treatment is preferably 0.4 to 3 seconds, thereby, preferred since it is possible to reduce the oxide or hydroxide of tin effectively.
[0057]
　Compound contained in the hot water is not particularly limited. There is no particular limitation on the hot water pH, if the pH is 5-8, it is possible to remove oxides or hydroxides of tin surface, the metallic tin uniformly, preferred.
[0058]
(2.5 anodic electrolysis process)
　Next, by anodic electrolysis process on Sn-plated steel sheet in an electrolytic solution, on the Sn-plated layer 20 to form a film 30 comprising zirconium oxide and tin oxide (No. 3 of the process). Thus, it is possible to produce the Sn plated steel sheet 100 according to this embodiment.
[0059]
　The cleaning process, tin oxide inevitably present on the surface of the zirconium oxide layer (not shown), to reduce the tin hydroxide and tin metal. Then, the Sn-plated steel sheet after the washing treatment by anodic electrolysis, tin oxide described above, the tin hydroxide and metallic tin is dissolved, it is possible to further reduce. Further, by anodic electrolysis treatment, XPS in the depth direction analysis, there depth position A element concentration is the largest Zr which is a zirconium oxide, a depth element concentration of Sn which is present as tin oxide is up to than the position B, it can be positioned on the surface side of the film 30, and the distance in the depth direction between the depth position a and depth position B to produce a Sn-plated steel sheet is 0.5nm or more .
[0060]
　The electrolyte solution used in the anodic electrolysis (hereinafter, referred to as anodic electrolysis treatment solution) is not particularly limited pH of preferably a alkalinity from weakly acidic. The alkaline weakly acidic here, pH is meant 3-14.
[0061]
　Examples of electrolyte contained in the anode electrolytic treatment solution described above, the alkali and alkaline earth metal hydroxides and carbonates, phosphates, organic acid salts, borates, sulfates, etc. may be mentioned. More specifically, sodium carbonate, sodium bicarbonate, sodium diphosphate, sodium citrate, ammonium one tartaric acid, and sodium sulfate.
　The concentration of the electrolyte is not particularly limited. The upper limit of the concentration of the electrolyte is also not particularly limited, if the concentration is too large to precipitate during storage, which may cause problems such as pipe clogging. Therefore, the concentration of the electrolyte is preferably not less than the solubility at 0 ℃ of the electrolyte.
　The concentration of the electrolyte is preferably a concentration in the electric conductivity satisfy 0.5S / m ~ 4S / m, and more preferably, the concentration satisfying 1S / m ~ 2.5S / m electrical conductivity. The electric conductivity may be measured using a commercially available electric conductivity meter, for example, it is possible to use a conductivity cell CT-27112B, such as manufactured by DKK-TOA Corporation.
　Further, Zr ion concentration of the anodic electrolytic treatment solution is less 270 ppm. If the Zr ions exceeds 270 ppm, it becomes coarse film and Zr ions are mixed into the coating 30, in order to not be sufficiently improved discoloration resistance upon heating.
[0062]
　The liquid temperature of the anodic electrolysis treatment liquid is not particularly limited, but is preferably from 5 ° C. ~ 60 ° C., more preferably from 15 ℃ ~ 50 ℃. If the temperature is sufficiently high, it is possible to increase the electrolytic efficiency, it is possible to more reliably form a film 30.
[0063]
　While current density during the anodic electrolysis treatment is not particularly limited, for example, 0.02 A / dm 2 ~ 50A / dm 2 is preferably set to. Current density is 0.02 A / dm 2 ~ 50A / dm 2 when a is a film 30 having a zirconium oxide and tin oxide according to the present embodiment can uniformly and stably formed. Current density is 0.02 A / dm 2 when it is more than can be relatively shortened electrolysis treatment time, it is possible to prevent a decrease in corrosion resistance after painting associated with the dissolution of the Sn-plated layer 20. On the other hand, the current density is 50A / dm 2 when it is less, since it is possible to suppress the excessive hydrogen generation on Sn-plated steel sheet, to prevent the dissolution of the Sn-plated layer 20 due to the pH increase production efficiency preferably the upper, it is possible to sufficiently improve the discoloration resistance and sulfidation blackening during heating by uniform tin oxide formation. Preferred current density range, 0.04 A / dm 2 ~ 10A / dm 2 is.
[0064]
　Processing time of anodic electrolysis treatment is not particularly limited, depending on the current density and electrode length and production rate (sheet passing speed), it can be arbitrarily determined.
[0065]
　The thickness distribution of the tin oxide in the film 30 can be mainly controlled by the amount of current during anodic electrolysis (quantity of electricity). Therefore, in order to obtain a film 30 according to this embodiment, preferably the amount of current during anodic electrolysis treatment 0.1 C / dm 2 ~ 10C / dm 2 , more preferably 0.2 C / dm 2 ~ 2.0 C / Dm 2 to.
[0066]
　As the solvent for the anodic electrolysis treatment solution, for example, can be used distilled water, and the like in water, such as distilled water. Energization pattern during anodic electrolysis treatment may be intermittent energization may be continuous energization.
Example
[0067]
　Subsequently, while showing Examples and Comparative Examples, a method for manufacturing the Sn-plated steel sheet and Sn-plated steel sheet according to the present invention will be specifically described. Incidentally, embodiments described below, merely only one example of a manufacturing method of the Sn plated steel sheet and Sn-plated steel sheet according to the present invention, limited to the example manufacturing method of the following Sn plated steel sheet and Sn-plated steel sheet according to the present invention not intended to be.
[0068]

　to a low carbon cold rolled steel sheet having a thickness of 0.2 mm, as a pretreatment, electrolytic alkali degreasing, washing with water, pickling and water washing by immersion in diluted sulfuric acid was performed. Then subjected to electrical Sn plating using phenolsulfonic acid bath, further followed by a heat melting treatment. Adhesion amount of Sn plating is about 2.8 g / m per one side 2 was the the standard, some test materials, was varied coating weight of Sn plating by changing the energizing time. Further, the test material which does not heat melting treatment after electrical Sn plating were also prepared together. Sn coating weight was identified by measuring the fluorescent X-ray method (manufactured by Rigaku Corporation ZSX Primus).
[0069]
　The Sn-plated steel sheet produced as above, and cathodic electrolysis in an aqueous solution containing zirconium fluoride, to form a zirconium oxide layer on the Sn plated steel sheet. Bath temperature was set to 35 ° C., and, pH is adjusted to 3 to 5, the current density and cathode electrolysis time was adjusted appropriately according to the desired Zr coating weight.
[0070]
　Further, the Sn-plated steel sheet to form a zirconium oxide layer, a cleaning process was carried out by immersing for 1 second in hot water at bath temperature 30 ° C..
　Thereafter, by anodic electrolysis treatment in the electric conductivity of 2.0S / m of sodium hydrogen carbonate solution (anolyte treatment liquid) to form a film. The liquid temperature of the anodic electrolysis treatment liquid was set to 25 ° C., and the current density of the anodic electrolysis treatment is 1A / dm 2 was set to. Note that in some level, changing the wash process conditions and anodic electrolysis treatment conditions. Processing time of anodic electrolysis treatment were appropriately adjusted. Further, Zr ion concentration of anodic electrolysis treatment liquid are as described in the table.
　As a comparative example, a test material which does not perform the anodic electrolysis treatment is formed only zirconium oxide, also test materials was conducted only anodic electrolysis treatment without forming a zirconium oxide were prepared together.
[0071]
　For Sn-plated steel sheet produced in this manner was a variety of evaluation described below.
　Zr coating weight per one surface was determined by ICP emission spectrometry.
[0072]
at XPS (ULVAC-PHI manufactured PHI Quantera SXM) in the depth direction analysis was tin oxide, metallic tin, a quantitative analysis in the depth direction of the zirconium oxide.
　In quantitative analysis, the binding energy position of Sn3d5 / 2, which corresponds to Sn which is present as tin oxide 485.8eV more 487.2eV or less, the binding energy position of Sn3d5 / 2, which corresponds to Sn which exist as metallic Sn is 484 .3eV above 485.5eV or less, the binding energy position of Zr3d5 / 2 of Zr present as zirconium oxide, or 182.0eV 182.9eV or less, and defines, tin oxide, metallic tin, 3 of zirconium oxide It was set to 100% at the species.
　In XPS, spectra affected by charging, etc. of the sample, for further have a (charge shift) potential peak position is shifted, the peak position correction by adsorption to have pollutants (carbon of organic matter) on the surface of the sample went. Specifically, in terms of peak position of carbon detected on the surface of the sample (C1s) is shifted the entire spectrum to be 284.8 eV, and the quantitative analysis.
[0073]
　Depth analysis, a peak was observed at the position of the binding energy corresponding to the metal Sn, and was the depth profiling to a depth no longer observed peaks at binding energy position corresponding to tin oxide. The sputtering conditions in the depth direction analysis, SiO 2 spacing 0.5nm in terms is Ar sputtering. In XPS depth elemental analysis, as the starting point of the surface of the film 30, the element concentration of the metal Sn is the extent to which the end point of the depth position to reach 90% was defined as film 30. Based on this definition, it was determined thickness of the film 30.
[0074]
　
　in the depth direction analysis results of XPS obtained in this way, element concentration of Zr present as zirconium oxide is a depth position A is the maximum, tin than present Sn depth position B element concentration is maximum as an oxide, positioned on the surface side of the film, and the distance in the depth direction between the depth position a and depth position B 0 the case is .5nm more than "Good", and the case is not the case was evaluated as "Bad".
　Note that "element concentration up" refers to a maximum value in a range of performing the depth analysis, if the maximum value in the range there is a plurality, and that refers to the maximum value of the maximum value.
　Also, when taking the maximum value at a plurality of depth positions, the average value of the depth position of the plurality of the "element concentration depth position is the maximum." For example, in FIG. 1, element concentration of Sn which is present as tin oxide, depth from the surface is taking 6.0 nm, 6.5 nm, a maximum at three places 7.0 nm. Depth position B in this case is based on the average value of the three positions, the position in the depth 6.5nm from the surface.
[0075]
　
　"Fair" and when the element concentration of Zr is less than 20% at a depth position A, "Good" and is less than 20% or more 30%, at 30 percent a certain case was evaluated as "VeryGood".
[0076]
　
　were measured in the depth direction of the distance from the surface of the film 30 to a depth position A. Further, by multiplying 1/3 to the thickness of the film 30 obtained in the manner described above, to determine the position of the depth position C is a depth position of 1/3 of the thickness from the surface of the film.
　The case depth position A is the surface side of the depth position C "Good", and the otherwise evaluated as "Fair".
[0077]

　against Sn-plated steel sheet prepared by the above method, the heating test of holding at 205 ° C. ~ 210 ° C. plate temperature for 30 minutes was performed in an air furnace. Variation of the color difference b * value before and after the heating test △ b * the seeking and evaluated.
　△ b * is the "VeryGood" as long as it is 1 or less, 1 if ultra-2 or less as "Good", as long as it is two ultra-3 or less as "Fair", and "Bad" if it is greater than 3, evaluation " VeryGood "," Good ", was passed the" Fair ".
　b * conforms to JIS Z 8722, measured using a Suga Tester manufactured by SC-GV5 a commercial colorimeter, b * measurement conditions, the light source C, total reflection, was measured diameter 30 mm.
[0078]

　coating adhesion was evaluated as follows.
　On the surface of the Sn plated steel sheet prepared by the above method, the epoxy resin paint commercial cans dry mass at 7 g / m 2 was coated, baked at a temperature of 200 ° C. 10 minutes before placed in room temperature for 24 hours. Thereafter, the obtained Sn-plated steel sheet, placed flaws reaching the steel sheet surface in a grid pattern (scratches at 3mm apart by vertically and horizontally seven), the coating adhesion by the tape peeling test with respect to the site evaluated.
　If the peeling of the paint film in all tape applying portion does not occur as "VeryGood", when the coating film grid outside had peeled as "Good", the coating film is not peeled off in a grid was evaluated as "Bad" in the case was.
　Evaluation was as acceptable in the case of "VeryGood" and "Good".
[0079]

　sulfidation blackening was evaluated as follows.
　On the surface of the Sn plated steel sheet prepared by the above method, 7 g / m of an epoxy resin paint commercially available cans in dry mass 2 was coated, baked at a temperature of 200 ° C. 10 minutes before placed in room temperature for 24 hours. Then cut the Sn plated steel sheet obtained to a predetermined size, sodium dihydrogen phosphate: 0.3%, sodium hydrogen phosphate: 0.7% L-cysteine hydrochloride: aqueous solution containing 0.6% I was immersed in. Put Sn-plated steel sheet after immersion in a sealed container and subjected to 60 minutes retorted at a temperature of 121 ° C.. From the appearance of the Sn plated steel sheet after retort treatment were evaluated sulfidation blackening.
　If the appearance before and after the test has not been completely changed to "VeryGood", if occurred 10 area% or less of blackening as "Good", and a "Bad" if the cause black 10 area percent strange evaluated.
　Evaluation, was passed in the case of "VeryGood" and "Good".
[0080]

　after painting corrosion resistance was evaluated in the following manner.
　On the surface of the Sn plated steel sheet prepared by the above method, 7 g / m of an epoxy resin paint commercially available cans in dry mass 2 was coated, baked at a temperature of 200 ° C. 10 minutes before placed in room temperature for 24 hours. Thereafter, the resulting Sn-plated steel sheet was cut into a predetermined size was dipped for 7 days at a temperature of 60 ° C. in a commercially available tomato juice. By visually occurrence or non-occurrence of rust after immersion was evaluated corrosion resistance after painting.
　If no cause rust at all as "Good", if it occurs 10 area% or less of rust as "Fair", 10 area% of the rust was evaluated as "Bad" if it occurs.
　Evaluation, was passed in the case of "Good" and "Fair".
[0081]

　Table 1 shows the result in the case of changing the content of the zirconium oxide film. In Table 1 do not specify the manufacturing methods, a zirconium concentration of the cathode electrolytic treatment solution in the production of the Sn plated steel sheet in Table 1 (zirconium fluoride) was set to 80 ~ 5000 ppm. After forming the zirconium oxide, Zr ion concentration was 10 ppm, and the electrical conductivity of 2.0S / m of sodium hydrogen carbonate solution (liquid: weakly acidic to alkaline) by anodic electrolysis treatment in, film It was formed. The liquid temperature of the anodic electrolysis treatment liquid was set to 25 ° C., energization amount of the anodic electrolytic treatment up to 1.6C / dm 2 was set to. As a comparison, in some instances to produce a test material without washing treatment and / or anodic electrolysis treatment.
[0082]
[Table 1]

[0083]
　As apparent from Table 1, in the present invention example was good none of the evaluation results. On the other hand, in the comparative example, resistance to discoloration during the heating was poor. In Comparative Example a1 ~ 6, it was poor coating adhesion, either sulfidation blackening and the corrosion resistance after coating are.
　Further, based on the results of Table 1 shows the relationship between the position and the color fastness upon heating depth position A in FIG. 3. As shown in FIG. 3, when located on the surface side of the depth position A depth position C (a depth position of 1/3 from the coating surface of the film thickness), preferably discoloration resistance can be obtained which was.
[0084]

　Table 2 shows the result of the case of changing the concentration of element Zr at depth position A. Element concentration of Zr in the depth position A was varied by changing the quantity of electricity in the anodic electrolysis treatment.
[0085]
[Table 2]

[0086]
　As apparent from Table 2, the inventive examples were excellent both of the evaluation results.
[0087]

　In Table 3 shows the differences in evaluation results obtained by changing the value of alpha / beta. The alpha / beta, was varied by changing the concentration of phosphate ions in the cathode electrolytic treatment bath.
[0088]
[table 3]

[0089]
　As apparent from Table 3, the inventive examples were excellent both of the evaluation results.
[0090]

　In Table 4 and 5 show the differences in evaluation results due to differences in the conditions of the cleaning process. In Table 4 the production conditions of each test material, showing the construction and evaluation of the obtained test material in Table 5.
　Although Table 4 does not describe the conditions for the anodic electrolysis treatment in all invention examples and comparative examples, the electrolyte of the anodic electrolytic treatment solution: sodium bicarbonate, Zr ion concentration of the anodic electrolytic treatment solution: 10 ppm, an anode pH of the electrolyte treatment solution: 8, the electric conductivity of the anodic electrolytic treatment solution: 2S / m, the liquid temperature of the anodic electrolytic treatment solution: 25 ° C., energization amount of anodic electrolysis: 0.5 C / dm 2 anode under the conditions of the electrolytic treatment was carried out.
[0091]
[Table 4]

[0092]
[table 5]

[0093]
　As apparent from Table 4 and 5, the inventive examples were good none of the evaluation results. On the other hand, the test material manufactured in Comparative Example d1, the discoloration resistance upon heating was poor.
[0094]

　The Tables 6-14 is the result when changing cathodic treatment conditions, cleaning conditions, the anodization conditions. In Table 6-11 the production conditions of the test material in each example, showing the structure and evaluation results of the obtained test material in Tables 12-14.
[0095]
[Table 6]

[0096]
[Table 7]

[0097]
[Table 8]

[0098]
[Table 9]

[0099]
[Table 10]

[0100]
[Table 11]

[0101]
[Table 12]

[0102]
[Table 13]

[0103]
[Table 14]

[0104]
　Table 12 - As is evident from 14, in the present invention example was better none of the evaluation results. On the other hand, in Comparative Examples e1 ~ e5, discoloration resistance upon heating was poor.
[0105]

　Table 15 and Table 16 are the results of different Zr ion concentration of the anodic electrolytic treatment solution. The production conditions are shown in Table 15, showing the structure and evaluation results of the Sn plated steel sheet obtained in Table 16.
[0106]
[Table 15]

[0107]
[Table 16]

[0108]
　As is apparent from Table 15 and 16, in the present invention example was better none of the evaluation results. On the other hand, in Comparative Example f1, f2, discoloration resistance upon heating was poor.
[0109]
　Having described in detail preferred embodiments of the present invention, the present invention is not limited to such an example. It would be appreciated by those skilled in the relevant field of technology of the present invention, within the scope of the technical idea described in the claims, it is intended to cover various changes and modifications , also these are understood as naturally belong to the technical scope of the present invention.
Industrial Applicability
[0110]
　As described above, in the Sn-plated steel sheet having a coating comprising zirconium oxide on the surface of the Sn plated steel sheet and tin oxide, the zirconium oxide coating weight of metallic Zr amount 0.2 mg / m 2 ~ 50 mg / m 2 is, further XPS depth profiling present depth position a element concentration is the largest Zr as zirconium oxide by is present element concentration depth is the largest of Sn position B as tin oxide than is the surface side of the film, and the distance in the depth direction is 0.5nm or more Sn-plated steel sheet between the depth position a and depth position B does not require the conventional chromate treatment to, discoloration resistance upon heating, the coating film adhesion, excellent sulfidation blackening. From this fact, as can materials friendly to the environment, food cans, can be widely used, such as in beverage cans, is extremely high utility value on the industry.
DESCRIPTION OF SYMBOLS
[0111]
　10 steel
　20 Sn-plated layer
　30 coating
　100 Sn-plated steel sheet

WE CLAIM

And the steel sheet,
　and the Sn plating layer provided on at least one surface of the steel sheet,
　the provided on the surface of the Sn plating layer, and the film containing zirconium oxide and tin oxide,
comprising a
　said zirconium in the coating the oxide content, 0.2 mg / m of a metal Zr amount 2 ~ 50 mg / m 2 a,
　the maximum in the depth direction analysis by X-ray photoelectron spectroscopy, the element concentration of Zr present as the zirconium oxide the depth position a is, than the depth position B element concentration is the largest Sn which is present as the tin oxide, positioned on the surface side of the film, and the depth and the depth position a distance in the depth direction between the position B is 0.5nm or more
Sn-plated steel sheet, characterized in that.
[Requested item 2]
　In the X-ray photoelectron spectroscopy according to the depth direction elemental analysis, the element concentration of Zr present as the zirconium oxide in the depth position A is 20% or more
, characterized in that, according to claim 1 Sn-plated steel sheet.
[Requested item 3]
　Said coating further comprises a phosphoric acid compound,
　in the film, the content of the phosphate compound in terms of P content alpha (Unit: mg / m 2 ) the content of the zirconium oxide was converted with a metal Zr content beta (unit: mg / m 2 ) value alpha / beta divided by is 0.2-2.0
, characterized in that, Sn-plated steel sheet according to claim 1 or claim 2.
[Requested item 4]
　The case that the thickness depth position C to a depth position of 1/3 of the coating from the surface of the film,
　the depth position A is located on the surface side of the depth position C
, wherein the to, Sn-plated steel sheet according to any one of claims 1-3.
[Requested item 5]
　Against steel plates Sn plating layer on at least one surface formed by performing cathodic electrolysis treatment in a solution containing zirconium ions, a step of forming a zirconium oxide on the Sn-plated layer,
　the cathodic electrolysis after the treatment, and performing a cleaning process by immersion or spraying or 0.3 seconds with warm water of more than 25 ° C.,
　carried out after the cleaning process, Zr ion concentration of anodic electrolysis treatment in the following electrolyte solution 270ppm a step of forming a film containing said zirconium oxide and tin oxide on the Sn-plated layer
having a
, wherein the method for producing a Sn-plated steel sheet.
[Requested item 6]
　The content of the zirconium oxide in the coating is, 0.2 mg / m of a metal Zr amount 2 ~ 50 mg / m 2 is,
　in depth analysis of the coating by X-ray photoelectron spectroscopy, as the zirconium oxide present depth position a element concentration is the largest Zr is greater than the depth position B element concentration is the largest Sn which is present as the tin oxide, positioned on the surface side of the film, and the distance in the depth direction between the depth position a and the depth position B is 0.5nm or more
and wherein the method for producing a Sn-plated steel sheet according to claim 5.
[Requested item 7]
　In the depth direction elemental analysis by X-ray photoelectron spectroscopy, the element concentration of Zr present as the zirconium oxide in the depth position A is 20% or more
, characterized in that, according to claim 5 or 6 method of manufacturing a Sn-plated steel sheet.
[Requested item 8]
　Said coating further comprises a phosphoric acid compound,
　in the film, the content of alpha (Unit: mg / m of the phosphate compound in terms of P content 2 ) the amount containing that the zirconium oxide in terms of metal Zr beta (unit: mg / m 2 ) value alpha / beta divided by is 0.2-2.0
, characterized in that, preparation of the Sn-plated steel sheet according to any one of claims 5-7 Method.