TWI676712B - Steel plate for container and manufacturing method thereof - Google Patents

Abstract

The steel sheet for a container according to the present invention is characterized by including a tin-plated steel sheet having a tin plating layer on the surface, a tin oxide film formed on the surface of the tin plating layer, and a surface of the tin oxide film, A tin phosphate film containing 0.1 mg / m ² or more and 3.0 mg / m ² or less of tin phosphate as the amount of P. The tin oxide film was in a 0.001 N hydrogen bromide aqueous solution, and the potential was scanned from the immersion potential to the negative side. When reducing the tin oxide film, there is a reduction current peak in the range of -800 ~ -500mV vs saturated KCl-Ag / AgCl reference electrode, and the A value is less than 1.0. Calculated for the reduction current-potential curve of the self-tin oxide film The amount of electricity required for the reduction of the tin oxide film is within the range of 1.5 mC / cm ^{2 to} 5.0 mC / cm ² .

Description

Container steel plate and manufacturing method thereof

The present invention relates to a steel material for a container, which is optimal for use as a container material for a beverage can, a food can, and the like, and is excellent in coating adhesion and tin oxidation resistance, and a method for manufacturing the same.

Synthetic treatment of tin-plated iron, which is a type of steel plate for containers used as a container material for beverage cans, food cans, etc., has been used in the past since it has excellent coating adhesion and tin oxidation resistance. deal with. On the other hand, from the standpoint of the recent reduction in environmental burden, it is preferable that in the manufacturing process of a steel sheet for a container, a synthetic treatment not containing hexavalent chromium is used. From such a background, a method of treating chromate and replacing it with phosphate was devised. For example, Patent Document 1 describes a method of controlling a electrolytic condition during the formation of a phosphate film to form a phosphate film excellent in tin oxidation resistance. In addition, Patent Document 2 describes a steel sheet for a container having a film containing tin oxide, tin phosphate, and a silanol group containing an organic compound on a tin plating layer. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2012-197495 95 [Patent Document 2] Japanese Patent Application Publication No. 2008-202094

[Questions to be Solved by the Invention]

However, the phosphate film system produced by the method described in Patent Document 1 lacks paint adhesion, and further, under high temperature and humidity environments, the inhibition of tin oxidation is insufficient. In addition, the steel sheet for containers described in Patent Document 2 is superior in coating adhesion because it provides a silanol group-containing organic compound layer on the surface, but is insufficient in suppressing tin oxidation.

The present invention has a structure made in view of the above-mentioned problems, and an object thereof is to provide a steel sheet for a container excellent in paint adhesion and tin oxidation resistance and a method for manufacturing the same. [Means for solving problems]

As a result of an intensive review by the inventors of the present invention in order to achieve the above-mentioned object, it was found that a tin oxide film was formed on a surface of a tin-plated steel sheet by a specific amount, and the form of the tin oxide film was appropriately controlled, and formed on the surface. In the case of a tin phosphate film, a steel sheet for a container excellent in coating adhesion and tin oxidation resistance can be obtained, and the present invention has been conceived.

The steel sheet for a container according to the present invention is characterized by comprising a tin-plated steel sheet having a tin plating layer on the surface, a tin oxide film formed on the surface of the tin plating layer, and a tin oxide film formed on the tin oxide film. On the surface, a tin phosphate film containing 0.1 mg / m ² or more and 3.0 mg / m ² or less of tin phosphate as the amount of P. The tin oxide film is in a 0.001 N hydrogen bromide aqueous solution, and the potential is scanned from the immersion potential to At the same time on the negative side, when reducing the aforementioned tin oxide film, there is a reduction current peak in the range of -800 ~ -500mV vs. saturated KCl-Ag / AgCl reference electrode, and the A value defined by the following formula (1) is less than 1.0 The amount of electricity required for the reduction of the tin oxide film calculated from the reduction current-potential curve of the aforementioned tin oxide film is within the range of 1.5 mC / cm ^{2 to} 5.0 mC / cm ² .

Here, Q ₁ means that it has the reduction current peak in the range of -600 ~ -500mV, which is the amount of electricity required for the reduction of the tin oxide film, and Q ₂ means that it has the reduction current peak on the side more negative than -600mV. The amount of electricity required to reduce the tin oxide film.

A method for manufacturing a steel sheet for a container according to the present invention is characterized by including, as an anode, applying a tin-plated steel sheet having a tin plating layer on its surface through an aqueous solution having a pH in a range of 8 to 13 inclusive. Electrolytic treatment, followed by water washing, followed by dipping the tin-plated steel sheet in a phosphate aqueous solution for 1.0 seconds or more and 5.0 seconds or less, or using the tin-plated steel sheet as an anode and applying 0.1A / dm ^{2 to} 10A / dm ² , A step of manufacturing a steel sheet for a container during an electrolytic treatment of 0.1 seconds to 2.0 seconds. [Inventive effect]

According to the present invention, it is possible to provide a steel sheet for a container excellent in paint adhesion and tin oxidation resistance, and a method for producing the same.

Hereinafter, the steel plate for containers and its manufacturing method according to the present invention will be described in detail.

The steel sheet for a container according to the present invention is tin-plated through a tin layer having a steel sheet and at least one layer selected from the group consisting of a Sn layer, an Fe-Sn alloy layer, and an Fe-Ni-Sn alloy layer on at least a part of the surface of the coated steel sheet. The coated tin is formed by plating a steel plate. The steel plate used as a material can be a steel plate for general containers. The tin plating layer may be a continuous layer or a discontinuous island shape. In addition, the tin plating layer may be provided on at least one side of the steel plate, or may be provided on both sides. The formation of the tin plating layer can be performed according to a known method according to the metal element contained. Hereinafter, the best form of a steel plate and a tin plating layer is explained in full detail.

[Steel plate] The type of the steel plate is not particularly limited, and generally, a steel plate (for example, an extremely low carbon steel plate or a low carbon steel plate) used as a container material can be used. The manufacturing method and material of the steel sheet are not particularly limited, and they are manufactured from ordinary steel sheet manufacturing processes through processes such as hot rolling, pickling, cold rolling, annealing, and temper rolling.

The steel sheet system may be formed by forming a nickel (Ni) -containing layer on the surface thereof and forming a tin plating layer on the Ni-containing layer as necessary. When tin plating is performed by using a steel plate having a Ni-containing layer, a tin plating layer containing island-like Sn can be formed, and the weldability is improved. The Ni-containing layer system may include nickel, and examples thereof include a Ni plating layer and a Ni-Fe alloy layer.

The method for imparting the Ni-containing layer to the steel sheet is not particularly limited, and examples thereof include a known method such as electroplating. In addition, in the case where a Ni-Fe alloy layer is provided as the Ni-containing layer, after Ni is provided on the surface of the steel plate by electroplating or the like, the Ni diffusion layer can be coordinated to form a Ni-Fe alloy layer through annealing. .

The amount of Ni in the Ni-containing layer is not particularly limited, but the amount of Ni conversion per metal on one side is preferably within a range of 50 mg / m ^{2 to} 2000 mg / m ² . If it is in the said range, it will be superior by sulfur blackening resistance, and it will become advantageous also in terms of cost.

[Tin Plating Layer] In the tin plating layer, the Sn adhesion amount per steel sheet is preferably within a range of 0.1 g / m ² or more and 15.0 g / m ² or less. If the amount of Sn deposited is within the above range, the appearance characteristics and corrosion resistance of the steel sheet for a container are excellent. Among these, at the point where these characteristics are more superior, the Sn adhesion amount is more preferably within the range of 0.2 g / m ^{2 to} 15.0 g / m ² , and at the point of more excellent processability, 1.0 g / m ^{2 is} 15.0 or more. It is more preferably within a range of g / m ² or less.

However, the amount of Sn deposited can be measured from the time of surface analysis by the electric quantity method or fluorescent X-ray. In the case of using fluorescent X-rays, a sample of Sn attachment amount that is known for the amount of metal Sn is used, and a calibration curve for the amount of metal Sn is specified beforehand, and then the amount of metal Sn is specified relatively using the same calibration curve.

The tin plating layer is a layer covering at least a part of the surface of the steel sheet, and may be a continuous layer, or a non-continuous island shape. The tin plating layer also includes a tin plating layer obtained by plating tin, or after tin plating, the tin is heated and melted by electric heating, etc., and is part of the lowest layer (tin plating / base interface) of the tin plating. A tin plating layer of an Fe-Sn alloy layer is formed. In addition, the tin plating layer includes tin plating for a steel sheet having a Ni-containing layer on the surface, and further, tin is heated and melted by electric heating and the like, and the lowermost layer (tin plating layer) is tin-plated. (Steel plate interface) partly forms a tin plating layer such as an Fe-Sn-Ni alloy layer, an Fe-Sn alloy layer.

As a method for producing a tin plating layer, a known method (for example, a plating method or a method of plating by immersing in molten Sn) can be mentioned. For example, using a tin phenolsulfonate plating bath, a tin methanesulfonate plating bath, or a halogen-based tin plating bath, the amount of adhesion per side is a specific amount (for example, 2.8 g / m ² ). After plating Sn on the surface of the steel sheet, reflow treatment is performed at a temperature above the melting point of Sn (231.9 ° C) to form a tin plating layer that forms the lowermost layer of the Fe-Sn alloy layer and the tin plating layer. By omitting the reflow process, a plating layer made of tin alone can be manufactured.

In addition, the steel sheet may have a Ni-containing layer on its surface, and a tin plating layer is formed on the Ni-containing layer. When performing a reflow process, the Fe-Sn-Ni alloy layer or the Fe-Sn alloy layer is formed equal to the tin single. The lowest layer of the body's plating layer (tin plating layer / steel plate interface).

[Tin oxide film] The steel sheet for a container according to the present invention is provided between a tin plating layer and a tin phosphate film, and has a tin oxide film. By appropriately controlling the amount and quality of the tin oxide film, it is possible to provide a steel sheet for a container excellent in tin oxidation resistance. Specifically, the reduction current-potential curve of a steel plate for a container described later has a reduction current peak of a tin oxide film in a range of -800 to -500 mV vs. a saturated KCl-Ag / AgCl reference electrode. The A value defined by the formula (1) is less than 1.0, and the amount of electricity required for the reduction of the tin oxide film calculated from the self-reduction current-potential curve is within the range of 1.5 mC / cm ^{2 to} 5.0 mC / cm ² .

Here, Q ₁ refers to the amount of electricity required for the reduction of tin oxide films with a reduction current peak in the range of -600 to -500 mV, and Q ₂ refers to the reduction current peak on the negative side of -600 mV. The amount of electricity required to reduce the tin oxide film.

The reduction current with a reduction current peak in the range of -600 ~ -500mV is estimated to be derived from SnO, and the reduction current with a reduction current peak on the negative side of -600mV is estimated to be derived from SnO ₂ and Sn- Reduction of oxide film of Fe or Sn-Fe-Ni alloy layer. In the case where the tin oxide film provided between the tin plating layer and the tin phosphate film is a SnO main body, the tin oxidation resistance is deteriorated. On the other hand, when the tin oxide film is mainly composed of SnO ₂ , that is, when the A value is less than 1.0, the tin oxidation resistance is improved. This series of SnO ₂ is compared with SnO. It is stable with respect to the passage of time in the atmosphere, and it can be estimated from the reason of tin oxidation over time that SnO ₂ can be prevented from being given to the point of time after the manufacture. However, when the tin oxide film is imparted by thickening, the aggregation failure of the tin oxide film becomes a starting point, and the paint adhesion is reduced. In addition, even if the tin oxide film is too thin, sufficient tin oxidation resistance cannot be obtained. From the above point of view, the amount of tin oxide film is preferably in the range of 1.5 mC / cm ² or more and 5.0 mC / cm ² or less in terms of the reduction power required for its reduction.

However, the reduction current-potential curve of a steel plate for a container can be obtained by immersing a steel plate for a container in a 0.001 N hydrogen bromide aqueous solution replaced with an inert gas such as Ar, and using saturated KCl-Ag / An AgCl electrode was measured when a platinum plate was used as the counter electrode, and the potential of the steel plate for a container was scanned from the immersion potential to the negative side at a scanning speed of 1 mV / sec. By subtracting the charging current and the reduction current accompanying hydrogen from the reduction current-potential curve obtained, the peak separation process can be used to separate the oxidation from SnO, SnO ₂ , and Sn-Fe or Sn-Fe-Ni alloy layers. The reduction current of the film (alloy Sn) reduction can be calculated from its peak area for the amount of electricity required for each reduction. Hereinafter, an example of a method for calculating the amount of electricity required for reduction will be described with reference to FIGS. 1 and 2.

1 (a) and 1 (b) are diagrams each showing an example of a reduction current-potential curve when the alloy Sn is present and when it is not present. Here, in FIGS. 1 (a) and (b), the curves L1, L2, and L3 each show the measured value of the reduction current, the background (reference line) current, and the measured value of the reduction current after the background current is removed. In addition, the background currents shown in Figs. 1 (a) and (b) are obtained from the following formula (2). The background current I is equal to the reduction current in the range of potential -0.9 to -0.8V. The measured values are uniformly obtained by adjusting the parameters α, β in Expression (2). As shown in Figures 1 (a) and (b), when the background current is removed from the measured value of the self-reduction current, the reduction current-potential curve obtained by subtracting the charging current and the reduction current accompanied by hydrogen can be obtained.

Here, I indicates the background current, I _ch indicates the charging current, I ₀ indicates the current at the immersion potential, and E ₀ indicates the immersion potential.

2 (a) and 2 (b) are graphs showing peak separation results in the cases shown in each of Figs. 1 (a) and 1 (b). Here, in Figures 2 (a) and (b), the curves L11, L12, L13, L14, and L15 show the reduction current-potential curves each minus the charging current and the reduction current accompanied by hydrogen, and the reduction current from SnO -Potential curve, reduction current-potential curve from SnO ₂ , reduction current-potential curve from alloy Sn, and a curve showing the sum of the curve L12 and the curve L13 and the curve L15. In addition, the current values of the curves L12, L13, and L14 are applied to the oxidation-reduction current of the substance adsorbed on the electrode surface. The following formula (3) is used to calculate the current values of the curves L11, L12, L13, and L14 as I, I ₁ , I ₂ , and I _{3 are obtained} by adjusting parameters n, A, Γ, and E ^{o in} Equation (3) such that I = I ₁ + I ₂ + I ₃ . Further, since the peak area of the curve L12, L13, L14, the respective calculated SnO, the desired SnO _2, Sn and alloys of reduction charge Q1, Q2, Q3. An example of the calculation result is shown in Table 1 below.

Here, the n-series electron number, the F-series Faraday constant, the A-series electrode area, the v-series scanning speed, the R-series gas constant, the T-series temperature, the Γ-series adsorption amount, the E-series electrode potential, and the E ^o- series display redox potential.

[Tin Phosphate Film] Next, a tin phosphate film disposed on the surface of the tin plating layer side of the above tin-plated steel sheet will be described. A tin phosphate film is a film which contains phosphoric acid and Sn as its components, and is formed using the processing liquid mentioned later. The tin phosphate film is formed in a range of 0.1 mg / m ² or more and 3.0 mg / m ² or less in terms of P-based adhesion amount (hereinafter, also referred to as “P adhesion amount”) per one side of a tin-plated steel sheet. . When the adhesion amount of P is less than 0.1 mg / m ² , the tin phosphate film, which contributes to the combination with the paint, cannot cover the entire surface of the tin plating layer, and the paint adhesion deteriorates. On the other hand, in the case where the P adhesion amount is more than 3.0 mg / m ² , the adhesion of the paint is deteriorated due to the aggregation failure of the tin phosphate film itself. If the amount of P adhered is within a range of 0.1 mg / m ^{2 to} 3.0 mg / m ² , the coating adhesion is excellent. When used in combination with the above-mentioned tin oxide film, the coating adhesion and tin oxidation resistance are excellent. superior. However, the amount of P adhesion can be measured by surface analysis of fluorescent X-rays.

[Manufacturing method of steel plate for containers] As a method for manufacturing a steel plate for containers according to the present invention, first, a tin-plated steel plate is immersed in an alkaline treatment solution, and the tin-plated steel plate is used as an anode, with an appropriate electric density. For electrolytic treatment, a tin oxide film is applied to the surface of the tin plating layer. Next, the tin-plated steel sheet immersed in a treatment solution described later, or the tin-plated steel sheet immersed in the treatment liquid becomes an anode and is subjected to electrolytic treatment. Hereinafter, the manufacturing method of the steel plate for containers concerning this invention is demonstrated.

[Pre-treatment process] (1) In the method for manufacturing a steel sheet for a container according to the present invention, a pre-treatment process described later is performed before a tin phosphate film formation process described later. The pretreatment process is a process of forming a tin oxide film on the surface of the tin plating layer side of the tin plated steel sheet when the tin plated steel sheet is electrolytically treated as an anode with respect to an alkaline pretreatment solution. When the tin-plated steel sheet is subjected to anodic electrolytic treatment through the previous treatment solution, a part of the tin-plated layer included in the tin-plated steel sheet becomes a tin oxide film containing tin oxide. The alkaline pretreatment liquid system is not particularly limited. Examples thereof include an aqueous solution of an alkali metal carbonate such as sodium carbonate or potassium carbonate, or an aqueous solution of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide.

The concentration of the components in the pretreatment solution is not particularly limited, but from the reason that a tin oxide film can be continuously and densely formed on the surface of a tin-plated steel sheet, it is preferable that the range is 5 g / L or more and 30 g / L or less. , And more preferably within the range of 10 g / L to 20 g / L. The pH of the pretreatment solution is based on the reason that tin oxide film can be continuously and densely formed on tin-plated steel plates. The range of 8 to 13 is preferable, and the range of 10 to 12 is Better. In the pre-treatment process, the amount of tin oxide film formed by the liquid temperature system of the pre-treatment liquid at the time of the treatment becomes an appropriate amount. From the reason that tin oxidation over time can be more suppressed, it is within a range of 20 ° C to 60 ° C. It is preferably, and it is more preferably within a range of 30 ° C to 50 ° C.

The electrolytic conditions in the pretreatment solution are electrolytically performed on the side of the tin-plated steel sheet as an anode. However, at this time, the optimum electric density is applied for the amount and quality of the tin oxide film. The absolute value of the optimal electric density is changed by the device through the impedance of the rectifier, steel plate, and other wiring. The optimal electric density conditions are measured under various conditions for the reduction current-potential curve of the reduction through the above-mentioned tin oxide film. If the A value is selected, it is less than 1.0, and the reduced electric quantity is 1.5 mC / cm ^{2 to} 8.0 mC / cm ² It is sufficient to have a charge density within the following range. However, after the electrolytic treatment in the pretreatment liquid, a water washing treatment may be applied as necessary.

[Tin phosphate film formation process] The tin phosphate film formation process is a process of forming a tin oxide film layer on the surface of the tin plating layer side of a tin plated steel sheet to form a tin phosphate film, in which tin is immersed in a treatment solution The process of anodic electrolytic plating on the plated steel plate (immersion treatment), or on the immersed tin plated steel plate. As the treatment liquid, a commercially available tin phosphate treatment liquid can be used. Examples thereof include tin phosphate treatment liquid PF-K5102 manufactured by Nihon Parkerizing. The immersion time of the tin-plated steel sheet is from the point that the P adhesion amount is kept within the range of 0.1 mg / m ^{2 to} 3.0 mg / m ² , and it is preferable that it is in the range of 1.0 seconds to 5.0 seconds, and is 2.0. It is more preferably within a range of from seconds to 4.0 seconds.

The dip-tin-plated steel sheet may be further subjected to anodic electrolytic treatment. In this case, a tin phosphate film can be formed in a shorter time as compared with the case of only dipping, which is advantageous in terms of cost. The electrolytic current density at the time of anodic electrolytic treatment is from the point of ensuring that the amount of P deposited is within a range of 0.1 mg / m ^{2 to} 3.0 mg / m ² , and is in a range of 0.1 A / dm ^{2 to} 10 A / dm ² The content within the range is preferably from 0.5 A / dm ^{2 to} 5 A / dm ² . In addition, the electrolysis time is from the point that the amount of P deposited is kept within the range of 0.1 mg / m ² or more and 3.0 mg / m ² or less, and it is preferably in the range of 0.1 seconds to 2.0 seconds, and is 0.2 seconds to 1.0. It is more preferable if it is within the range of seconds. however. After immersion in the treatment liquid or electrolytic treatment, if necessary, washing treatment may be performed with water at room temperature to 90 ° C. [Example]

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

[Manufacture of tin-plated steel sheet] First, an electrolytic degreased steel sheet (T4 original sheet) with a thickness of 0.22 mm was used to form a nickel-plated layer on both sides using a Watt bath from the amount of Ni deposited per single sheet shown in Table 2 below. The Fe-Ni alloy layer (Ni-containing layer) was formed on both sides when annealing was performed at 700 ° C in a 10 vol.% H ₂ +90 vol.% N ₂ environment to diffuse and permeate the nickel plating. Next, for a steel plate having a Ni-containing layer on the surface layer, a tin plating bath is used. After forming the Sn layer on both sides from the Sn adhesion amount of each sheet shown in Table 2, reflow soldering is performed at a melting point of Sn or more. Processing, the tin plating layer is formed on both sides of the T4 original plate.

[Formation of film] 浸渍 Immersion in a plated steel sheet with a 10g / L sodium carbonate or a sodium hydroxide aqueous solution at a bath temperature of 30 ° C and a pH of 11, and anodizing under the pretreatment conditions shown in Table 2 below To form a tin oxide film. Next, the obtained steel sheet with a tin oxide film was washed with water, and a treatment solution (solvent: water) at 60 ° C (solvent: water) was added at 100 g / L to which tin phosphate treatment solution PF-K5102 manufactured by Nihon Parkerizing was added. The electrolytic conditions shown (current density, immersion time, and electrolysis time) were subjected to anode electrolytic treatment. Thereafter, the obtained tin oxide film-coated steel sheet was washed with water at 85 ° C. and dried at room temperature by using a blower to form the film of the present invention on both sides of the steel sheet. As a result, a test material for a steel plate for a container is produced. Then, the test material of the produced steel plate for containers was evaluated for paint adhesion and tin oxidation resistance by the method described later. The evaluation results are shown in Table 3 below.

[Paint Adhesiveness] After applying an epoxy phenol-based coating having an adhesion amount of 50 mg / dm _{2 to} the surface of the steel plate for a container to be produced, it was fired at 210 ° C. for 10 minutes. Next, the steel plate for a container to be coated and fired was cut into a checkerboard grid of 100 squares (the area of one square is 1 mm ² ) with a cutter, and thereafter, the tape was peeled off and evaluated based on the evaluation criteria shown below. Evaluate paint peeling rate. Practically, if the evaluation is ◎ or ○, it can be evaluated as a composition that is superior in coating adhesion.

：: 0.0% or more and less than 10.0% (equivalent to chromate-treated materials) ○: 10.0% or more and less than 60.0% ×: 60% or more

[Tin oxidation resistance] After the production is completed (within 1 week after the production), the steel sheet for containers is stored under the environment of a temperature of 50 ° C and a relative humidity of 80% for 2 weeks, and the surface color of the steel sheet before and after the evaluation is evaluated. Specifically, the b value was measured using SQ-2000 manufactured by Nippon Denshoku Industries, Ltd., and the Δb value (b value of the steel sheet after the test-b value of the steel sheet before the test) was evaluated from the evaluation criteria shown below. In addition, if the evaluation is ○, it is evaluated as a composition excellent in tin oxidation resistance.

○: Δb value is 0.0 or more and less than 1.0 Δ: Δb value is 1.0 or more and less than 2.0 ×: Δb value is 2.0 or more

From the results shown in Tables 2 and 3, it was confirmed that the examples of the present invention are superior to paint adhesion and tin oxidation resistance. In contrast, in a comparative example where the amount of P deposited on the tin phosphate film is not within the range of 0.1 mg / m ^{2 to} 3.0 mg / m ² , or the reduction amount of the tin oxide film is larger than 5.0 mC / cm ² In the example, the paint adhesion was poor. Further, in the comparative example in which the A value was 1.0 or more and the reduction amount of the tin oxide film was less than 1.5 mC / cm ² , the tin oxidation resistance was poor. [Industrial possibilities]

According to the present invention, it is possible to provide a steel sheet for a container excellent in paint adhesion and tin oxidation resistance, and a method for producing the same.

FIG. 1 is a diagram showing an example of a reduction current-potential curve when the alloy Sn is present and when it is not present. FIG. 2 is a graph showing an example of peak separation results.

Claims (3)

A steel sheet for a container, comprising a tin-plated steel sheet having a tin plating layer on the surface, a tin oxide film formed on the surface of the tin plating layer, and a surface of the tin oxide film, as A tin phosphate film containing tin phosphate with a P content of 0.1 mg / m ^{2 to} 3.0 mg / m ² or less. The tin oxide film is a 0.001 N hydrogen bromide aqueous solution, and the potential is scanned from the immersion potential to the negative side. At the same time, when reducing the aforementioned tin oxide film, there is a reduction current peak in the range of -800 ~ -500mV vs. saturated KCl-Ag / AgCl reference electrode, and the A value defined by the postscript [Number 1] is less than 1.0 in order to reduce the The amount of electricity required for the reduction of the tin oxide film calculated from the reduction current-potential curve of the tin film is within the range of 1.5 mC / cm ^{2 to} 5.0 mC / cm ² [Number 1] A = Q ₁ / Q ₂ … ( 1) Here, Q ₁ represents the amount of electricity required for the reduction of tin oxide films with a reduction current peak in the range of -600 to -500 mV, and Q ₂ represents the oxidation with a reduction current peak on the negative side of -600 mV. The amount of electricity required to restore the tin film. A method for manufacturing a steel sheet for a container, characterized in that an electrolytic solution is applied to a tin-plated steel sheet having a tin plating layer on its surface through an aqueous solution having a pH in the range of 8 to 13 inclusive. A tin oxide film is formed on the surface of the tin plating layer, and then washed with water. Then, the tin plated steel plate is immersed in a phosphate aqueous solution for 1.0 to 5.0 seconds, and tin phosphate is formed on the surface of the tin oxide film. Coating to produce steel plates for containers. A method for manufacturing a steel sheet for a container, characterized in that an electrolytic solution is applied to a tin-plated steel sheet having a tin plating layer on its surface through an aqueous solution having a pH in the range of 8 to 13 inclusive. On the surface of the tin plating layer, a tin oxide film is formed, and then washed with water. Then, in a phosphate aqueous solution, a tin plated steel plate is used as an anode, and is applied at 0.1 A / dm ^{2 to} 10 A / dm ² for 0.1 seconds to 2.0 seconds. The following electrolytic treatment forms a tin phosphate film on the surface of the tin oxide film to manufacture a steel sheet for a container.