Title of the invention: Sn-plated steel sheet and method for manufacturing Sn-plated steel sheet
Technical field
[0001]
　The present invention relates to a Sn-plated steel sheet and a method for manufacturing a Sn-plated steel sheet.
　The present application claims priority based on Japanese Patent Application No. 2018-036587 filed in Japan on March 1, 2018, the contents of which are incorporated herein by reference.
Background technology
[0002]
　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. After the Sn-plated steel plate is given a beautiful metallic luster by heat-melting after plating, a chromate film is formed on the Sn-plated by a chromate treatment such as an electrolytic treatment using a hexavalent chromate solution or a dipping treatment. Often given. The effects of this chromate film are the prevention of yellowing of the appearance by suppressing the oxidation of the Sn plating surface, the prevention of deterioration of the coating adhesion due to the cohesive destruction of tin oxide when used after painting, and the black sulfide resistance. Improvement of degeneration, etc.
[0003]
　On the other hand, in recent years, due to increasing awareness of the environment and safety, it is required not only that the final product does not contain hexavalent chromium but also that the chromate treatment itself is not performed. However, as described above, the Sn-plated steel sheet in which the chromate film does not exist has a yellowish appearance due to the growth of tin oxide, a decrease in coating film adhesion, and a decrease in sulfide blackening resistance.
[0004]
　For this reason, some Sn-plated steel sheets that have been subjected to a film treatment instead of the chromate film have been proposed.
[0005]
　For example, Patent Document 1 below proposes a Sn-plated steel sheet 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 Patent Document 2 below, a film containing a reaction product of Al and P, at least one of Ni, Co, and Cu, and a silane coupling agent was formed by a treatment using a solution containing aluminum phosphate. Sn-plated steel sheets have 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, Patent Document 4 and Patent Document 5 below propose a steel sheet for a container having a chemical conversion treatment film containing zirconium, phosphoric acid, phenolic resin and the like.
Prior art literature
Patent documents
[0006]
Patent Document 1: Japanese Patent Application Laid-Open No. 2004-60052
Patent Document 2: Japanese Patent Application Laid-Open No. 2011-174172
Patent Document 3: Japanese Patent Application
Laid-Open No. 63-290292 Patent Document 4: Japanese Patent Application Laid-Open No. 2007- 284789 JP
Patent Document 5: Japanese Patent 2010-13728 JP
Non-patent literature
[0007]
Non-Patent Document 1: "Surface Analytical Chemistry Selection Book X-ray Photoelectron Spectroscopy" edited by Japan Surface Science Society, Maruzen Co., Ltd., P.M. 83
Outline of the invention
Problems to be solved by the invention
[0008]
　However, as a result of studies by the present inventors, the Sn-plated steel sheet and its manufacturing method proposed in Patent Documents 1 to 5 cannot sufficiently suppress the growth of tin oxide over time, and are resistant to tin oxide. It was clarified that yellowing and coating adhesion may be insufficient.
[0009]
　The present invention has been made in view of the above problems, and an object of the present invention is further excellent in yellowing resistance, coating film adhesion, and sulfide blackening resistance without performing conventional chromate treatment. The purpose is to provide a Sn-plated steel sheet and a method for manufacturing a Sn-plated steel sheet.
Means to solve problems
[0010]
　In order to solve the above problems and achieve the object concerned, the present inventors have diligently studied. As a result, by forming a layer containing zirconium oxide and tin oxide on the surface of the Sn-plated steel sheet, yellowing resistance, coating adhesion, and sulfide blackening resistance can be achieved without chromate treatment. It has been found that an even better Sn-plated steel sheet can be realized. The gist of the present invention completed based on the above findings is as follows.
[0011]
[1] The Sn-plated steel sheet according to one aspect of the present invention includes a steel sheet and a base metal-plated steel sheet having a Sn-plated layer on at least one side of the steel sheet; and a zirconium oxide located on the base metal-plated steel sheet. A film layer containing tin oxide and; are provided, and the amount of Sn adhered to one side is 0.1 g / m 2 or more and 15 g / m 2 or less, and the content of the zirconium oxide in the film layer is The amount of metal Zr is in the range of 1 mg / m 2 or more and 30 mg / m 2 or less, and the peak position of the binding energy of Sn3d 5/2 in the film layer by X-ray photoelectron spectroscopy of tin oxide is the metal Sn. It is within the range of 1.4 eV or more and less than 1.6 eV from the peak position of the binding energy of, and the amount of electricity required for the reduction of the tin oxide is within the range of more than 5.0 mC / cm 2 and 20 mC / cm 2 or less.
[2] The method for producing a Sn-plated steel sheet according to one embodiment of the present invention, on at least one surface of the steel sheet, a Sn 0.1 g / m 2 or more 15 g / m 2The base metal plated steel sheet on which the Sn plating layer containing the following is formed is subjected to a zirconium immersion treatment in a solution containing zirconium ions or a cathode electrolysis treatment in a solution containing zirconium ions. A first step of forming a zirconium oxide layer containing an oxide; after the first step, the base metal plated steel sheet on which the zirconium oxide layer is formed is placed in an oxygen-containing atmosphere. It has a second step of heat-treating under conditions that satisfy both the following formulas 1 and 2 with respect to the heating temperature T in which the unit is K and the heating time t in which the unit is How.
　0.11 × exp (2400 / T)
　The steel sheet 1 used as the base material of the Sn-plated steel sheet 10 according to the present embodiment is not particularly specified, and is any steel sheet used for Sn-plated steel sheets for general containers. , Anything can be used. Examples of such a steel sheet 1 include low carbon steel and ultra-low carbon steel. Further, the manufacturing method and material of the steel sheet 1 to be used are not particularly specified. For example, a steel sheet manufactured through processes such as casting, hot rolling, pickling, cold rolling, annealing, and temper rolling. Can be used as appropriate.
[0021]

　Sn plating is applied to at least one surface of the steel sheet 1 as described above to form the Sn plating layer 2. The Sn plating layer 2 improves the corrosion resistance of the steel sheet 1 after coating. The term "Sn plating" as used herein includes not only plating with metal Sn, but also plating with impurities mixed in metal Sn and plating with trace elements contained in metal Sn.
[0022]
　The method of applying Sn plating to the surface 1a of the steel sheet 1 is not particularly specified, but for example, a known electroplating method is preferable, and a melting method of plating by immersing the steel sheet 1 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.
[0023]
　After Sn plating, the steel sheet 1 to which the Sn plating layer 2 has been applied may be subjected to a heat melting treatment in which the steel sheet 1 coated with the Sn plating layer 2 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 10 becomes glossy, and an alloy layer of Sn and Fe is formed between the Sn-plated 2 and the steel sheet 1, further improving the corrosion resistance after painting.
[0024]

　The Sn-plated steel sheet 10 according to the present embodiment has a zirconium oxide on the surface of the base metal-plated steel sheet 3 having the Sn-plated layer 2 as described above. It has a film layer 4 containing both tin oxide. As described above, the content of the zirconium oxide in the film layer 4 is in the range of 1 mg / m 2 or more and 30 mg / m 2 or less per one side in terms of the amount of metal Zr . The tin oxide in the film layer 4 has a peak position of the binding energy of Sn3d 5/2 by XPS within a range of 1.4 eV or more and less than 1.6 eV from the peak position of the binding energy of the metal Sn, and tin oxide. The amount of electricity required for the reduction is within the range of more than 5.0 mC / cm 2 and 20 mC / cm 2 or less.
[0025]
　The above-mentioned "Sn3d 5/2 " means the energy level of the electron in Sn as described in the above-mentioned Non-Patent Document 1. More specifically, in Sn, it means the energy level of 3d electrons in which the spins are parallel.
[0026]
　The Sn-plated steel sheet 10 according to the present embodiment has a film layer 4 in which the zirconium oxide and tin oxide coexist as described above on the surface 2a of the Sn-plated layer 2, thereby preventing yellowing and adhering to the coating film. The properties and sulfide blackening resistance can be further improved. It should be noted that the zirconium oxide alone or tin oxide alone cannot sufficiently improve the yellowing resistance, the coating film adhesion, and the sulfurization blackening resistance. The reason for this is not clear, but based on a detailed investigation by the present inventors, it is considered as follows.
[0027]
　Conventionally, tin oxide has been considered to be a cause of yellowing, but as a result of examination by the present inventors, when a uniform and sufficient amount of tin oxide is produced on a Sn-plated steel sheet, yellowing resistance is reversed. It turns out that it tends to improve. Further, it was found that when a uniform and sufficient amount of tin oxide is generated on the Sn-plated steel sheet, not only the yellowing resistance but also the sulfide blackening resistance tends to be improved at the same time. This is because yellowing occurs due to the repetition of elution of micrometal tin on the Sn-plated steel sheet and the oxidation phenomenon, whereas the Sn-plated surface is covered with tin oxide to elute micrometal tin. It is thought that it can be suppressed. In order to obtain such an effect, it is necessary to set the amount of tin oxide in which the amount of electricity required for reduction of tin oxide is in the range of more than 5.0 mC / cm 2 and 20 mC / cm 2 or less. When the amount of electricity required for reduction of tin oxide exceeds 20 mC / cm 2 , it is not preferable because the coating film adhesion is inferior. The lower limit of the amount of electricity required for the reduction of tin oxide is preferably 7.0 mC / cm 2 , and more preferably 8 mC / cm 2 . The upper limit of the amount of electricity required for the reduction of tin oxide is preferably 15 mC / cm 2 , and more preferably 12 mC / cm 2 . The "electric amount required for reduction of tin oxide" indicates the amount of electricity obtained as the product of the time required for reduction and removal of tin oxide in the film layer 4 of the Sn-plated steel sheet 10 and the current value. , It is a numerical value substantially corresponding to the amount (thickness) of the film layer 4.
[0028]
　In order to obtain the above effects of tin oxide, it is necessary that the zirconium oxide coexists in the film layer 4. This is because the zirconium oxide improves the brittleness of the tin oxide-containing film and improves the coating film adhesion. Further, the zirconium oxide itself also has an effect of improving the sulfurization blackening resistance. In order to obtain such an effect, the content of the zirconium oxide needs to be in the range of 1 mg / m 2 or more and 30 mg / m 2 or less in terms of the amount of metal Zr . When the amount of metal Zr is less than 1 mg / m 2 , embrittlement of the film containing tin oxide cannot be suppressed. On the other hand, when the amount of metal Zr exceeds 30 mg / m 2 , the content of zirconium oxide is excessive, and conversely, the adhesion of the coating film is lowered. The lower limit of the content of the zirconium compound is preferably 3 mg / m 2 , and more preferably 5 mg / m 2 . The upper limit of the content of the zirconium compound is preferably 10 mg / m 2 , and more preferably 8 mg / m 2 .
[0029]
　For tin oxide, the peak position of the binding energy of Sn3d 5/2 by XPS needs to be within the range of 1.4 eV or more and less than 1.6 eV from the peak position of the binding energy of the metal Sn. If tin oxide has a binding energy value outside the above range, the coating film adhesion is not stable.
[0030]
　The film layer 4 containing these zirconium oxides and tin oxide may be in a mixed state of both, or may be a solid solution of the oxide, and its existence state does not matter. Further, it does not matter if any element such as P, Fe, Ni, Cr, Ca, Na, Mg, Al, Si and the like is further contained in these oxides. That is, as the component of the film layer 4, other components (phosphorus compound, fluoride, etc.) may be further contained in addition to the zirconium oxide and tin oxide.
[0031]
　Here, the amount of Zr adhered is obtained by immersing the Sn-plated steel plate 10 having the film layer 4 according to the present embodiment on the surface in an acidic solution such as hydrofluoric acid and sulfuric acid to dissolve it. The solution is taken as a value measured by chemical analysis such as high frequency inductively coupled plasma (ICP) luminescence analysis method. Alternatively, the amount of Zr attached may be determined by fluorescent X-ray measurement.
[0032]
　The amount of electricity required for the reduction of tin oxide is measured by the following method. That is, 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 10 according to the present embodiment is cathodically electrolyzed with a constant current of 0.06 mA / cm 2. To do. At this time, the amount of electricity required for reduction of tin oxide can be obtained from the product of the time required for reduction and removal of tin oxide and the current value.
[0033]
　Further, the peak position of the binding energy of Sn3d 5/2 by XPS can be measured by a known method using a known XPS measuring device.
[0034]
In the
　Sn galvanized steel sheet 10 according to the present embodiment, the Sn adhesion amount per one side is 0.1 g / m 2 or more and 15 g / m 2 or less as the metal Sn amount . As will be described in detail below, the coating layer 4 of the Sn-plated steel sheet 10 according to the present embodiment is obtained by heat-treating a Sn-plated steel sheet (material) on which a zirconium oxide layer is formed under predetermined conditions to perform Sn plating. It is formed by diffusing Sn in layer 2 into a zirconium oxide layer. Therefore, in the Sn-plated steel sheet 10 according to the present embodiment, the Sn adhesion amount per one side is the content of Sn existing in the Sn-plated layer 2 and not diffused in the film layer 4 and the Sn content in the film layer 4. It is the total value with the metal Sn conversion amount of tin oxide present in.
[0035]
　In the Sn-plated steel sheet 10 according to the present embodiment, when the Sn adhesion amount per one side is less than 0.1 g / m 2 , the corrosion resistance after painting is inferior, which is not preferable. Further, when the Sn adhesion amount per side exceeds 15 g / m 2 , the effect of Sn to improve the corrosion resistance after coating is sufficient, and further increase in the adhesion amount is not preferable from an economical point of view, and the coating film adheres. Sex also tends to decline. In the Sn-plated steel sheet 10 according to the present embodiment, the lower limit of the Sn adhesion amount per one side is preferably 1.0 g / m 2 , and more preferably 2.0 g / m 2 . The upper limit of the amount of Sn adhered to one side is preferably 10 g / m 2 , and more preferably 7.0 g / m 2 .
[0036]
　Here, the amount of Sn adhered per side as described above is, for example, a value measured by the electrolytic method or the fluorescent X-ray method described in JIS G 3303.
[0037]
(Regarding the Manufacturing Method of Sn Plated Steel Sheet 10) The manufacturing method of the Sn plated steel sheet according to
　the present embodiment will be described in detail below. In the method for producing a Sn-plated steel sheet according to the present embodiment , a Sn-plated layer 2 is formed on at least one side of the steel sheet 1 so that the amount of Sn adhered to one side is 0.1 g / m 2 or more and 15 g / m 2 or less. The base metal plated steel sheet 3 is used as a material.
[0038]
　Here, the method for producing the base metal plated steel sheet 3 is not particularly limited, and the known steel sheet 1 having a desired mechanical strength (for example, tensile strength, etc.) is subjected to a known plating method. It can be manufactured by performing Sn plating so that the amount of Sn plating adhered to one side is 0.1 g / m 2 or more and 15 g / m 2 or less. It is also possible to use a known Sn-plated steel sheet (material) that has been previously Sn-plated so that the amount of adhesion per one side is within the above range as the base metal-plated steel sheet 3.
[0039]
　Subsequently, a method for forming the film layer 4 containing zirconium oxide and tin oxide will be described in detail. In order to form the film layer 4 according to the present embodiment, first, a zirconium oxide layer containing a zirconium oxide is formed on the Sn plating layer 2 forming the base metal plated steel sheet 3.
[0040]
　The zirconium oxide layer containing the zirconium oxide contains the zirconium ion-containing solution or the zirconium ion-containing solution in the base material plated steel sheet 3 on which the Sn plating layer 2 is formed. By performing the cathode electrolysis treatment in the solution, it can be formed on the base metal plated steel plate 3.
[0041]
　However, in the dipping treatment, the surface of the base metal plated steel sheet 3 as a base is etched to form a zirconium oxide layer containing a zirconium oxide, so that the amount of adhesion tends to be non-uniform. Since the processing time is long, it is disadvantageous for industrial production. On the other hand, in the cathode electrolysis treatment, a uniform film can be obtained due to the combination of forced charge transfer, surface cleaning by hydrogen generation at the steel sheet interface, and adhesion promoting effect by increasing the pH value. Further, in this cathode electrolysis treatment, the coexistence of nitrate ions and ammonium ions in the treatment liquid enables short-time treatment of about several seconds to several tens of seconds, which is extremely advantageous industrially. Therefore, it is preferable to use a method by cathodic electrolysis (cathode electrolysis treatment) for forming the zirconium oxide layer containing the zirconium oxide according to the present embodiment.
[0042]
　In the following, the case where the cathode electrolysis treatment is performed to form the zirconium oxide layer will be described in detail, but the conditions related to the solution other than the conditions peculiar to the cathode electrolysis treatment such as the current density will be described in detail by the immersion treatment. It is also applicable to the case of forming.
[0043]
　Here, 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). The zirconium ion concentration in the solution is preferably 100 ppm or more and 4000 ppm or less, for example. Further, there is no problem even if other components such as fluorine ion, ammonium ion, nitrate ion and sulfate ion are contained in the solution containing zirconium ion.
[0044]
　Here, the liquid temperature of the solution for cathodic electrolysis (cathode electrolytic solution) is not particularly specified, but is preferably in the range of, for example, 10 ° C. or higher and 50 ° C. or lower. Cathodic electrolysis at 50 ° C. or lower enables the formation of a dense and uniform film structure formed by very fine particles. On the other hand, when the liquid temperature is less than 10 ° C, the film formation efficiency is poor, and when the outside temperature is high such as in summer, it is necessary to cool the solution, which is not only economical and also reduces the corrosion resistance after painting. there's a possibility that. Further, when the liquid temperature exceeds 50 ° C., the zirconium oxide film structure to be formed becomes non-uniform, defects, cracks, microcracks, etc. occur, making it difficult to form a dense film, which becomes a starting point of corrosion and the like. It is not preferable because it may become.
[0045]
　The pH value of the cathode electrolytic solution is not particularly specified, but is preferably 3 or more and 5 or less. If the pH value is less than 3, the production efficiency of zirconium oxide may decrease, and if the pH value exceeds 5, a large amount of precipitation occurs in the solution, resulting in continuous productivity. May decrease.
[0046]
　In addition, in order to adjust the pH value of the cathode electrolytic solution and improve the electrolytic efficiency, for example, nitric acid, aqueous ammonia and the like may be contained in the cathode electrolytic solution. In particular, in order to shorten the time required for the cathode electrolysis treatment, it is preferable to contain nitric acid and aqueous ammonia in the cathode electrolytic solution.
[0047]
　Further, the current density in the cathode electrolysis treatment is preferably in the range of 0.05 A / dm 2 or more and 50 A / dm 2 or less , for example . When the current density is less than 0.05 A / dm 2 , the efficiency of forming the zirconium oxide is lowered, and it becomes difficult to stably form the film layer containing the zirconium oxide, resulting in yellowing resistance and denaturation. Not only the sulfide blackening resistance is lowered, but also the corrosion resistance after painting may be lowered, which is not preferable. On the other hand, when the current density exceeds 50 A / dm 2 , the zirconium oxide formation efficiency is too high, and zirconium oxide which is coarse and has poor adhesion may be formed, which is not preferable. The lower limit of the current density range is more preferably 1 A / dm 2 , and even more preferably 2 A / dm 2 . The upper limit of the current density range is more preferably 10 A / dm 2 , and even more preferably 6 A / dm 2 .
[0048]
　When forming the zirconium oxide layer, the time for cathode electrolysis does not matter. The cathodic electrolysis time may be appropriately adjusted according to the current density with respect to the target Zr adhesion amount. For example, when the cathodic electrolysis treatment is performed within the current density range as described above, the energization time is 0.3. It can be about 5 seconds.
[0049]
　Further, as the solvent of the solution used for the cathode electrolysis treatment, for example, distilled water or the like can be used, but it is not specified in water such as distilled water, and it depends on the material to be dissolved, the forming method and the like. , Can be selected as appropriate.
[0050]
　Zirconium in the cathodic electrolysis is, for example, H 2 ZrF 6 can be used zirconium complexes such as as a source of zirconium. Zr in the zirconium complex as described above becomes Zr 4+ due to an increase in the pH value at the cathode electrode interface and exists in the cathode electrolytic solution. Such zirconium 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 formed.
[0051]
　Further, as the energization pattern at the time of cathode electrolysis, there is no problem whether it is continuous energization or intermittent energization.
[0052]
　The film layer 4 containing the zirconium oxide and tin oxide according to the present embodiment is obtained by heat-treating the base metal plated steel sheet 3 on which the zirconium oxide layer containing the zirconium oxide as described above is formed under predetermined conditions. Obtained by doing. Specifically, after forming a zirconium oxide layer on the Sn plating layer 2 of the base metal plated steel sheet 3, the temperature T (unit: K) and the time t (unit: hour) in an oxygen-containing atmosphere. The Sn-plated steel sheet 10 according to the present embodiment can be obtained by heating the following equations 101 and 102 under conditions that satisfy both of the following equations. That is, by diffusing Sn in the Sn plating layer 2 into the zirconium oxide layer by the heat treatment as described in detail below, the diffused Sn is oxidized to tin oxide. By such heat treatment, the amount of tin oxide produced corresponds to the amount of electricity required for reduction as described above, and the peak position of the binding energy of Sn3d 5/2 by XPS of tin oxide is as described above. It will be within the range.
[0053]
　0.11 x exp (2400 / T)
　A low-carbon cold-rolled steel sheet (corresponding to steel sheet 1) having a thickness of 0.2 mm is pretreated with electrolytic alkali degreasing, water washing, dilute sulfuric acid immersion pickling, water washing, and then phenol. Electron Sn plating was performed using a sulfonic acid bath, and then heat melting treatment was performed. The standard amount of Sn plating adhered was about 2.8 g / m 2 per side , but for some test materials, the amount of Sn plating adhered 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 Corporation).
[0061]
　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 zirconium concentration in the cathode electrolyte was 1400 ppm. Further, the bath temperature of the cathode electrolytic solution is adjusted to 35 ° C., and the pH value of the cathode electrolytic solution is adjusted to be 3 or more and 5 or less, and the current density and the cathode electrolytic time are adjusted according to the target amount of Zr adhered. Adjusted appropriately. The current density and cathode electrolysis time at the time of preparing each test material are as shown in Table 1 below.
[0062]
　Further, the Sn-plated steel sheet on which the zirconium oxide layer is formed is held at various heating temperatures and heating times as shown in Table 1 below to form a film layer containing zirconium oxide and tin oxide. It was. For comparison, a test material (No. 1B, No. 3B) in which only the zirconium oxide layer is formed and not heat-treated, and a test material (No. 7B) in which only the heat treatment is performed without forming the zirconium oxide. Was also made together. In addition, some of the test materials were subjected to anodic electrolysis treatment in an aqueous sodium carbonate solution before the formation of the zirconium oxide to change the structure of tin oxide (No. 5B, No. 6B). The Sn-plated steel sheet thus produced was evaluated in various ways as shown below. In addition, in some test materials, zirconium oxide was formed by alternating electrolysis treatment in which cathode electrolysis and anodic electrolysis were alternately repeated in an aqueous solution containing zirconium fluoride (No. 9B).
[0063]
[Zr adhesion amount] The Zr adhesion amount
　per side of the film layer of each test material was measured by a fluorescent X-ray method using ZSX Primus manufactured by Rigaku Corporation. The obtained Zr adhesion amount is also shown in Table 1 below.
[0064]
[Amount of tin oxide] For
　each test material , cathode electrolysis was performed at a constant current of 0.06 mA / cm 2 in a 0.001 mol / L hydrobromic acid aqueous solution from which dissolved oxygen was removed by bubbling nitrogen gas , and tin oxide was used. The amount of electricity required for reduction of tin oxide was measured from the product of the time required for reduction and removal of tin oxide and the current. The measured amount of electricity is also shown in the column of "Amount of tin oxide" in Table 1 below.
[0065]
[Peak position in XPS] For
　each test material, the peak position of the binding energy of Sn3d 5/2 was measured using XPS (PHI Quantera SXM manufactured by ULVAC-PHI), and the peak from the peak position of the binding energy of the metal Sn was measured. The position shift amount was calculated. The obtained shift amount is also shown in the column of "Binding energy peak position of Sn3d 5/2 " in Table 1 below .
[0066]
[Yellow-resistant denaturation]
　Yellow-resistant denaturation was evaluated as follows.
　A wet test was conducted in which each test material prepared as described above was placed in a constant temperature and humidity chamber maintained at 40 ° C. and a relative humidity of 80% for 4 weeks, and the amount of change in the color coordinate b * value before and after the wet test. Δb * was obtained and evaluated. If the amount of change Δb * is 1 or less, it is 3 points, if it exceeds 1 and 2 or less, it is 2 points, if it is 2 to 3, it is 1 point, if it exceeds 3, it is 0 points, and the evaluation is 1 point. The above was passed. The color coordinate b * was measured using a commercially available color difference meter SC-GV5 manufactured by Suga Test Instruments Co., Ltd. , and the measurement conditions for the color coordinate b * were a light source C, total reflection, and a measurement diameter of 30 mm.
[0067]
[Sulfide-resistant blackening] The
　sulfurization-resistant blackening was evaluated as follows.
　A commercially available epoxy resin paint for cans was applied to the surface of each test material prepared as described above at a dry mass of 7 g / m 2, then baked at 200 ° C. for 10 minutes, and left at room temperature for 24 hours. Then, each of the obtained test materials was cut into a predetermined size, and 0.3% by mass of sodium dihydrogen phosphate, 0.7% by mass of sodium hydrogen phosphate, and 0.6% by mass of L-cysteine ​​hydrochloride were cut. Was immersed in an aqueous solution containing each of these, retorted at 121 ° C. for 60 minutes in a sealed container, and evaluated from the appearance after the test. If no change in appearance is observed before and after the test, 2 points will be given, and if slight blackening is observed (if the blackened area is 10% or less), 1 point will be given to the area exceeding 10% of the test surface. If blackening was observed, the score was 0, and a rating of 1 or higher was passed.
[0068]
[Coating film adhesion] The
　coating film adhesion was evaluated as follows.
　Each test material prepared as described above is subjected to a wet test by the method described in the above [Yellow Degeneration], and then a commercially available epoxy resin paint for cans is applied to the surface at a dry mass of 7 g / m 2 to 200. It was baked at ° C. for 10 minutes and left at room temperature for 24 hours. Then, each of the obtained test materials 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 site. 2 points if all the coating film on the taped part is not peeled off, 1 point if peeling of the coating film is found around the scratched part of the grid, and 0 if peeling of the coating film is found in the grid. The score was 1 or higher, and the score was 1 or higher.
[0069]
[Corrosion resistance after painting] The corrosion resistance after
　painting was evaluated as follows.
　A commercially available epoxy resin paint for cans was applied to the surface of each test material 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, each of the obtained test materials was cut into a size of 40 mm × 40 mm, and the presence or absence of rust after being immersed in commercially available tomato juice in a temperature environment of 60 ° C. for 7 days was visually evaluated. If no rust is found, 2 points are given, if slight rust is found (if the rusted area is 5% or less), 1 point is given, and if rust exceeds 5%, 0 point is given, and 1 point is evaluated. The above was passed.
[0070]
[Comprehensive performance]
　As the total performance, the total of the scores of various performances is calculated, and when the total value is 8 points or 9 points, it is defined as "Very Good", and when it is 6 points or 7 points, it is defined as "Good". If there are 0 points in any one of the performances, the total value is set to 0 points and the score is set to "Bad", and the grades Very Good, Good, and Fair are passed. And said.
[0071]
[table 1]

[0072]
　As is clear from Table 1 above, it can be seen that the test materials corresponding to the invention examples have good performance. On the other hand, it can be seen that the test material corresponding to the comparative example is inferior in any of yellowing resistance, coating film adhesion, sulfurization blackening resistance, and corrosion resistance after coating.
[0073]
(Example 2)
　A low-carbon cold-rolled steel sheet having a thickness of 0.2 mm is subjected to electrolytic alkaline degreasing, washing with water, pickling with dilute sulfuric acid, washing with water, and then electro-Sn plating using a phenol sulfonic acid bath. After that, it was heat-melted. The amount of Sn adhered was 2.8 g / m 2 per side .
[0074]
　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 zirconium concentration in the cathode electrolyte was 1400 ppm. Further, the bath temperature of the cathode electrolytic solution is adjusted to 35 ° C., and the pH value of the cathode electrolytic solution is adjusted to be 3 or more and 5 or less, and the current density and the cathode electrolytic time are adjusted so that the Zr adhesion amount is 5 mg / m 2 . It was adjusted appropriately so as to be.
[0075]
　Further, the Sn-plated steel sheet on which the zirconium oxide layer was formed was held at various heating temperatures and heating times to form a film layer containing zirconium oxide and tin oxide, and each of the obtained Sn-plated steel sheets was formed. Was used as a test material.
[0076]
　For each of the obtained test materials, various performances were evaluated in the same manner as in the method described in Example 1 above, and the total performance was performed from the total score in each evaluation item. The evaluation criteria for overall performance are the same as in Example 1. The results are summarized in Table 2 below. Further, on the coordinate plane defined by the heating temperature T [° C.] and the heating time t [hour], the evaluation results of the obtained overall performance are plotted at the positions corresponding to the combination of the heating temperature and the heating time of each test material. did. The resulting plot is shown in FIG.
[0077]
[Table 2]

[0078]
　Note that FIG. 2 also shows the curves defined by the leftmost side and the rightmost side in each of the above equations 101, 103 and 104.
[0079]
　As is clear from FIG. 2, when the heat treatment is performed under the conditions within the range of the present embodiment, good performance is obtained, while the heat treatment is performed under the conditions outside the range of the present embodiment. In some cases, it can be seen that good performance cannot be obtained.
[0080]
　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 ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.
Industrial applicability
[0081]
　As described above, the Sn-plated steel sheet according to the present invention is excellent in yellowing resistance, coating adhesion, and sulfide blackening resistance without requiring conventional chromate treatment, and therefore, it can be used as an environment-friendly can material. It can be widely used for food cans, beverage cans, etc., and has extremely high industrial utility value.
Description of the sign
[0082]
　1 Steel plate
　2 Sn plating layer
　3 Base material plated steel sheet
　4 Film layer
　10 Sn plated steel sheet
The scope of the claims
[Claim 1]
　Steel, and at least one surface the base material coated steel sheet and having a Sn plating layer on the steel sheet;
　located in the base material plated steel sheet on the coating layer containing the zirconium oxide and tin oxide;
equipped with,
　per side The amount of Sn adhered is 0.1 g / m 2 or more and 15 g / m 2 or less, and
　the content of the zirconium oxide in the film layer is 1 mg / m 2 or more and 30 mg / m 2 or less in terms of the amount of metal Zr. The peak position of the binding energy of
　Sn3d 5/2 by X-ray photoelectron spectroscopy of the tin oxide in the film layer is 1.4 eV or more and less than 1.6 eV from the peak position of the binding energy of the metal Sn. The Sn-plated steel sheet is within the range of 5.0
　mC / cm 2 and the amount of electricity required for the reduction of tin oxide is within the range of more than 5.0 mC / cm 2 and 20 mC / cm 2 or less
.
[Claim 2]
　A base-plated steel sheet having a Sn-plated layer containing 0.1 g / m 2 or more and 15 g / m 2 or less of Sn formed on at least one side of the steel sheet is immersed in a solution containing zirconium ions, or A first step of forming a zirconium oxide layer containing a zirconium oxide by performing a cathode electrolysis treatment in a solution containing zirconium ions;
　after the first step, the zirconium oxide layer. The condition that both the following formulas 1 and 2 regarding the heating temperature T in which the unit is K and the heating time t in which the unit is How are satisfied in the atmosphere containing oxygen in the base metal plated steel sheet in which A
method for producing a Sn-plated steel sheet, which comprises a second step of heat-treating with .
　0.11 × exp (2400 / T)