JP6610794B2 - Steel plate for container and manufacturing method thereof - Google Patents

Description

  The present invention relates to a steel plate for containers that is suitable for application to container materials such as beverage cans and food cans, and is excellent in paint adhesion and tin oxidation resistance, and a method for producing the same.

  Chromate treatment is conventionally used as a chemical conversion treatment for tinplate, which is one of the steel plates for containers used as containers for beverage cans and food cans, because of its excellent paint adhesion and tin oxidation resistance. I came. On the other hand, from the viewpoint of reducing environmental burdens in recent years, chemical conversion treatment that does not contain hexavalent chromium is desired in the manufacturing process of steel plates for containers. From such a background, a method of replacing chromate treatment with phosphate treatment has been devised. For example, Patent Document 1 describes a method of forming a phosphate film excellent in tin oxidation resistance by controlling electrolysis conditions in the phosphate film formation process. Patent Document 2 describes a steel plate for containers having a coating containing tin oxide, tin phosphate, and a silanol group-containing organic compound on a tin plating layer.

JP 2012-197495 A JP 2008-202094 A

  However, the phosphate film produced by the method described in Patent Document 1 has poor paint adhesion, and tin oxide was not sufficiently suppressed under a high temperature and high humidity environment. Moreover, although the steel plate for containers described in patent document 2 is excellent in coating-material adhesiveness, since the silanol group containing organic compound layer is provided on the surface, it was inadequate for suppression of tin oxidation.

  This invention is made | formed in view of the said subject, The objective is to provide the steel plate for containers which is excellent in coating-material adhesiveness and tin-oxidation resistance, and its manufacturing method.

  The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, formed a specific amount of tin oxide film on the surface of the tin-plated steel sheet, appropriately controlling the form of the tin oxide film, By forming a tin phosphate film on the surface, it was found that a steel plate for containers excellent in paint adhesion and tin oxidation resistance was obtained, and the present invention was conceived.

The steel plate for containers according to the present invention includes a tin-plated steel plate having a tin-plated layer on the surface, a tin oxide film formed on the surface of the tin-plated layer, and P formed on the surface of the tin oxide film. and a tin phosphate coating containing 0.1 mg / m ² or more 3.0 mg / m ² or less of tin phosphate as the amount, the tin oxide coating, dipping a potential in a hydrogen bromide aqueous 0.001N When the tin oxide film is reduced while sweeping from the potential to the base side, it has a reduction current peak in the range of −800 to −500 mV vs saturated KCl—Ag / AgCl reference electrode, and is defined by the following formula (1). The A value is less than 1.0, and the amount of electricity required for the reduction of the tin oxide film calculated from the reduction current-potential curve of the tin oxide film is 1.5 mC / cm ² or more and 5.0 mC / cm ² or less. It is in the range.

ここで、Ｑ₁は、−６００〜−５００ｍＶの範囲内に還元電流ピークを有する酸化錫皮膜の還元に要する電気量を表し、Ｑ₂は、−６００ｍＶより卑側に還元電流ピークを有する酸化錫皮膜の還元に要する電気量を表す。

Here, Q ₁ represents the amount of electricity required for the reduction of the tin oxide film having a reduction current peak in the range of −600 to −500 mV, and Q ₂ is a tin oxide having a reduction current peak on the base side from −600 mV. It represents the amount of electricity required to reduce the film.

In the method for producing a steel plate for containers according to the present invention, electrolytic treatment is performed using a tin-plated steel plate having a tin-plated layer on the surface as an anode in an aqueous solution having a pH in the range of 8 to 13, and then washed with phosphoric acid. A tin-plated steel sheet is immersed in a salt solution for 1.0 to 5.0 seconds, or 0.1 A / dm ² or more and 10 A / dm ² for 0.1 to 2.0 seconds with the tin-plated steel sheet as an anode. It includes the step of producing a steel plate for containers by performing the following electrolytic treatment.

  ADVANTAGE OF THE INVENTION According to this invention, the steel plate for containers excellent in coating-material adhesiveness and tin-oxidation resistance, and its manufacturing method can be provided.

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 diagram illustrating an example of the peak separation result.

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

  A steel plate for containers according to the present invention is a tin comprising at least one layer selected from a steel plate and a Sn layer covering at least a part of the surface of the steel plate, a Fe—Sn alloy layer, and a Fe—Ni—Sn alloy layer. And a tin-plated steel sheet having a plating layer. As a raw steel plate, a general container steel plate can be used. The tin plating layer may be a continuous layer or a discontinuous island shape. Moreover, the tin plating layer should just be provided in the at least single side | surface of the steel plate, and may be provided in both surfaces. Formation of a tin plating layer can be performed by a well-known method according to the contained metal element. Hereinafter, the suitable aspect of a steel plate and a tin plating layer is explained in full detail.

〔steel sheet〕
The kind of steel plate is not particularly limited, and a steel plate (for example, an extremely low carbon steel plate or a low carbon steel plate) that is usually used as a container material can be used. The manufacturing method, material, etc. of the steel plate are not particularly limited, and the steel plate is manufactured through a normal slab manufacturing process through processes such as hot rolling, pickling, cold rolling, annealing, and temper rolling.

  If necessary, a steel sheet having a nickel (Ni) -containing layer formed on the surface thereof may be used, and a tin plating layer may be formed on the Ni-containing layer. By performing tin plating using a steel sheet having a Ni-containing layer, a tin plating layer containing island-shaped Sn can be formed, so that weldability is improved. The Ni-containing layer only needs to contain nickel, and examples thereof include a Ni plating layer and a Ni—Fe alloy layer.

  The method for applying the Ni-containing layer to the steel sheet is not particularly limited, and examples thereof include a known method such as electroplating. Moreover, when providing a Ni-Fe alloy layer as a Ni-containing layer, the Ni diffusion layer can be coordinated by forming Ni on the steel sheet surface by electroplating or the like, and then annealing to form a Ni-Fe alloy layer.

The amount of Ni in the Ni-containing layer is not particularly limited, and it is preferable that the amount of metal Ni converted on one side is in the range of 50 mg / m ^{2 to} 2000 mg / m ² . If it is in the above-mentioned range, it is more excellent in resistance to sulfur blackening and is advantageous in terms of cost.

[Tin plating layer]
The Sn adhesion amount per one surface of the steel plate in the tin plating layer is preferably in the range of 0.1 g / m ² or more and 15.0 g / m ² or less. When the Sn adhesion amount is within the above range, the outer appearance characteristics and corrosion resistance of the steel plate for containers are excellent. Among these, the Sn adhesion amount is more preferably in the range of 0.2 g / m ² or more and 15.0 g / m ² or less in terms of these characteristics being more excellent, and 1.0 g / m ^{2 in} terms of excellent workability. More preferably, it is within the range of 15.0 g / m ² or less.

  The Sn adhesion amount can be measured by surface analysis using a coulometric method or fluorescent X-ray. When fluorescent X-rays are used, a calibration curve related to the amount of metal Sn is specified in advance using a sample of the amount of Sn deposited with a known amount of metal Sn, and the amount of metal Sn is specified relatively using the calibration curve. .

  The tin plating layer is a layer covering at least a part on the surface of the steel plate, and may be a continuous layer or a discontinuous island shape. As the tin plating layer, a tin plating layer obtained by plating tin, or after tin plating, tin is heated and melted by energization heating or the like, and the Fe-Sn alloy is formed on the tin plating bottom layer (tin plating / base metal interface). A tin plating layer in which a part of the layer is formed is also included. In addition, as the tin plating layer, tin plating is performed on a steel sheet having a Ni-containing layer on the surface, and further tin is heated and melted by energization heating or the like, and Fe— A tin plating layer in which a Sn—Ni alloy layer, a Fe—Sn alloy layer or the like is partially formed is also included.

As a method for producing the tin plating layer, a known method (for example, an electroplating method or a method of immersing and plating in molten Sn) may be mentioned. For example, a phenol sulfonic acid tin plating bath, a methane sulfonic acid tin plating bath, or a halogen-based tin plating bath is used, and the amount of adhesion per one surface is adjusted to a predetermined amount (for example, 2.8 g / m ² ). After Sn is electroplated, a reflow treatment is performed at a temperature equal to or higher than the melting point of Sn (231.9 ° C.) to produce a tin plating layer in which a Fe—Sn alloy layer is formed in the lowermost layer of the tin plating layer. When the reflow process is omitted, a plating layer of simple tin can be produced.

  In addition, when the steel sheet has a Ni-containing layer on the surface, a tin plating layer is formed on the Ni-containing layer, and when reflow treatment is performed, the bottom layer of the tin plating layer (tin plating layer / steel sheet interface) is formed. An Fe—Sn—Ni alloy layer, an Fe—Sn alloy layer, or the like is formed.

[Tin oxide film]
The steel plate for containers according to the present invention has a tin oxide film between the tin plating layer and the tin phosphate film. By appropriately controlling the quantity and quality of the tin oxide film, a steel plate for containers having excellent tin oxidation resistance can be provided. Specifically, in the reduction current-potential curve of the steel plate for containers described later, the reduction current peak of the tin oxide film is within the range of −800 to −500 mV vs saturated KCl—Ag / AgCl reference electrode, and is shown below. The A value defined by Equation (1) is less than 1.0, and the amount of electricity required for reduction of the tin oxide film calculated from the reduction current-potential curve is 1.5 mC / cm ² or more and 5.0 mC / cm. Within ² or less.

ここで、Ｑ₁は−６００〜−５００ｍＶの範囲内に還元電流ピークを有する酸化錫皮膜の還元に要する電気量を表し、Ｑ₂は−６００ｍＶより卑側に還元電流ピークを有する酸化錫皮膜の還元に要する電気量を表す。

Here, Q ₁ represents the amount of electricity required for reduction of a tin oxide film having a reduction current peak in the range of −600 to −500 mV, and Q ₂ is a tin oxide film having a reduction current peak on the base side from −600 mV. Represents the amount of electricity required for reduction.

A reduction current having a reduction current peak in the range of −600 to −500 mV is derived from the reduction of SnO, and a reduction current having a reduction current peak on the base side from −600 mV is SnO ₂ and Sn—Fe or Sn—Fe—Ni. It is presumed to originate from the reduction of the alloy layer oxide film. When the tin oxide film provided between the tin plating layer and the tin phosphate film is mainly SnO, the tin oxidation resistance deteriorates. On the other hand, when the tin oxide film is mainly SnO ₂ , that is, when the A value is less than 1.0, the tin oxidation resistance is improved. This is presumably because SnO ₂ is more stable with time in the atmosphere than SnO, and tin oxidation over time can be suppressed by adding SnO ₂ from the time immediately after production. However, when the tin oxide film is applied thickly, the cohesive failure of the tin oxide film becomes a starting point, and the paint adhesion is lowered. Moreover, even if the tin oxide film is too thin, sufficient tin oxidation resistance cannot be obtained. From the above viewpoint, the amount of the 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 amount of reducing electricity required for the reduction.

The reduction current-potential curve of the vessel steel plate is obtained by immersing the vessel steel plate in a 0.001N hydrogen bromide aqueous solution substituted with an inert gas such as Ar, and using a saturated KCl-Ag / AgCl electrode as a reference electrode. Can be measured by sweeping the potential of the steel plate for containers from the immersion potential to the base side at a sweep rate of 1 mV / sec using a platinum plate as a counter electrode. By subtracting the charging current and the reduction current accompanying hydrogen generation from the resulting reduction current-potential curve and performing peak separation treatment, SnO, SnO ₂ and Sn—Fe or Sn—Fe—Ni alloy layer oxide film (alloy Sn) ) Can be separated, and the amount of electricity required for each reduction can be calculated from the peak area. Hereinafter, an example of a method for calculating the amount of electricity required for reduction will be described with reference to FIGS.

  FIGS. 1A and 1B are diagrams showing examples of reduction current-potential curves when the alloy Sn is present and when it is not present. Here, in FIGS. 1A and 1B, curves L1, L2, and L3 respectively show the actual value of the reduction current, the background (baseline) current, and the actual value of the reduction current after removal of the background current. Show. Further, the background current shown in FIGS. 1A and 1B is an actual measurement of the reduction current in the range where the background current I obtained by the following formula (2) is in the range of −0.9 to −0.8V. It was obtained by adjusting the parameters α and β in the formula (2) so as to coincide with the values. As shown in FIGS. 1A and 1B, a reduction current-potential curve obtained by subtracting the charging current and the reduction current associated with the generation of hydrogen can be obtained by removing the background current from the actual measurement value of the reduction current. it can.

ここで、Ｉはバックグラウンド電流、Ｉ_chは充電電流、Ｉ₀は浸漬電位での電流値、Ｅ₀は浸漬電位を示す。

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

FIGS. 2A and 2B are diagrams showing peak separation results in the cases shown in FIGS. 1A and 1B, respectively. Here, in FIGS. 2A and 2B, curves L11, L12, L13, L14, and L15 are reduction current-potential curves obtained by subtracting the charging current and the reduction current associated with hydrogen generation, respectively, and the reduction derived from SnO. A current-potential curve, a reduction current-potential curve derived from SnO ₂ , a reduction current-potential curve derived from alloy Sn, and a curve indicating the sum of curves L12, L13, and L15 are shown. Further, the current values of the curves L12, L13, L14 are obtained by applying the following formula (3) representing the oxidation-reduction current of the substance adsorbed on the electrode surface, and the current values of the curves L11, L12, L13, L14, respectively. I, I ₁ , I ₂ , and I ₃ were obtained by adjusting parameters n, A, Γ, and E ^o in Equation (3) so that I = I ₁ + I ₂ + I ₃ . Then, electric quantities Q1, Q2, and Q3 required for reducing SnO, SnO ₂ , and alloy Sn were calculated from the peak areas of the curves L12, L13, and L14. An example of the calculation result is shown in Table 1 below.

ここで、ｎは電子数、Ｆはファラデー定数、Ａは電極面積、ｖは掃引速度、Ｒは気体定数、Ｔは温度、Γは吸着量、Ｅは電極電位、Ｅ^oは酸化還元電位を示す。

Here, n is the number of electrons, F is the Faraday constant, A is the electrode area, v is the sweep rate, R is the gas constant, T is the temperature, Γ is the amount of adsorption, E is the electrode potential, and E ^o is the redox potential. .

[Tin phosphate coating]
Next, the tin phosphate film disposed on the surface of the tin-plated steel sheet on the tin plating layer side will be described. The tin phosphate film is generally a film containing phosphoric acid and Sn as its components, and is formed using a treatment liquid described later. The tin phosphate coating has a P-converted adhesion amount (hereinafter also referred to as “P adhesion amount”) per side of a tin-plated steel sheet within a range of 0.1 mg / m ^{2 to} 3.0 mg / m ^2. Is formed. When the P adhesion amount is less than 0.1 mg / m ² , the paint adhesion deteriorates because the tin phosphate coating that contributes to bonding with the paint cannot cover the entire surface of the tin plating layer. On the other hand, when the P adhesion amount is more than 3.0 mg / m ² , the paint adhesion deteriorates due to the cohesive failure of the tin phosphate coating itself. If the P adhesion amount is in the range of 0.1 mg / m ² or more and 3.0 mg / m ² or less, the paint adhesion is excellent, and in combination with the above-described tin oxide film, the paint adhesion and tin oxidation resistance are improved. Excellent. Note that the P adhesion amount can be measured by surface analysis using 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 plating layer is obtained by immersing a tin plating steel plate in an alkaline processing liquid and electrolytically treating it with an appropriate electric density so that the tin plating steel plate becomes an anode. A tin oxide film is applied to the surface of the film. Next, the tin-plated steel sheet is immersed in a treatment liquid described later, or electrolytic treatment is performed so that the tin-plated steel sheet immersed in the treatment liquid becomes an anode. Hereinafter, the manufacturing method of the steel plate for containers which concerns on this invention is demonstrated.

[Pretreatment process]
In the method for manufacturing a steel plate for containers according to the present invention, a pretreatment step described later is performed before a tin phosphate film forming step described later. The pretreatment step is a step of forming a tin oxide film on the surface of the tin-plated steel sheet on the tin plating layer side by subjecting the tin-plated steel sheet to an electrolytic treatment with an alkaline pretreatment liquid so as to serve as an anode. By subjecting the tin-plated steel sheet to anodic electrolytic treatment with a pretreatment liquid, a part of the tin-plated layer of the tin-plated steel sheet becomes a tin oxide film containing tin oxide. The alkaline pretreatment liquid is not particularly limited. Examples include aqueous solutions of alkali metal carbonates such as sodium carbonate and potassium carbonate, and aqueous solutions of alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.

  The component concentration in the pretreatment liquid is not particularly limited, but is preferably in the range of 5 g / L or more and 30 g / L or less because the tin oxide film can be continuously and densely formed on the surface of the tin-plated steel sheet. A range of 10 g / L or more and 20 g / L or less is more preferable. The pH of the pretreatment liquid is preferably in the range of 8 to 13 and preferably in the range of 10 to 12 because the tin oxide film can be continuously and densely formed on the tin-plated steel sheet. It is more preferable. In the pretreatment step, the temperature of the pretreatment liquid when performing the treatment is 20 ° C. or more and 60 ° C. or less because the amount of tin oxide film formed is an appropriate amount and tin oxidation over time can be further suppressed. The range of 30 degreeC or more and 50 degrees C or less are more preferable.

As electrolysis conditions in the pretreatment liquid, electrolysis is performed so that the tin-plated steel sheet side becomes an anode. In this case, an optimum electric density is applied in order to obtain the above-described amount and quality of the tin oxide film. The optimum absolute value of the electric quantity density varies depending on the resistance of a rectifier, a steel plate, other wiring, etc., and therefore depends on the device. The optimum electric quantity density condition is that the above-described reduction current-potential curve by reduction of the tin oxide film is measured under each condition, the A value is less than 1.0, and the reduced electric quantity is 1.5 mC / cm ² or more and 8.0 mC. An electric quantity density that falls within the range of / cm ² or less may be selected. In addition, you may perform a water-washing process as needed after the electrolytic treatment in a pre-processing liquid.

[Tin phosphate film formation process]
The tin phosphate film forming step is a step of forming a tin phosphate film after forming a tin oxide film layer on the surface of the tin-plated steel sheet on the tin plating layer side, and immersing the tin-plated steel sheet in the treatment liquid (Immersion treatment) or a step of subjecting the immersed tin-plated steel sheet to an anodic electrolytic treatment. A commercially available tin phosphate treatment solution can be used as the treatment solution. For example, a tin phosphate treatment solution PF-K5102 manufactured by Nippon Parkerizing Co., Ltd. may be mentioned. The immersion time of the tin-plated steel sheet is within the range of 1.0 second or more and 5.0 second or less from the viewpoint of securing the P adhesion amount within the range of 0.1 mg / m ² or more and 3.0 mg / m ² or less. It is preferable that it is within a range of 2.0 seconds or more and 4.0 seconds or less.

A tin-plated steel sheet may be immersed and further subjected to anodic electrolysis. In this case, compared with the case of only immersion, the tin phosphate film can be formed in a shorter time, which is advantageous in terms of cost. The electrolytic current density during the anodic electrolysis is 0.1 A / dm ² or more and 10 A / dm from the viewpoint of securing the P adhesion amount within the range of 0.1 mg / m ² or more and 3.0 mg / m ² or less. It is preferably in the range of ² or less, and more preferably in the range of 0.5 A / dm ² or more and 5 A / dm ² or less. The electrolysis time is within the range of 0.1 second to 2.0 seconds from the viewpoint of securing the P adhesion amount within the range of 0.1 mg / m ^{2 to} 3.0 mg / m ^2. Is more preferable, and it is more preferably within a range of 0.2 seconds to 1.0 seconds. In addition, after immersion in a process liquid or electrolytic treatment, you may perform a washing process with water of room temperature to 90 degreeC as needed.

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

[Manufacture of tinned steel sheet]
First, a steel plate (T4 original plate) having a thickness of 0.22 mm was electrolytically degreased and a nickel plating layer was formed on both sides with a Ni adhesion amount per one side shown in Table 2 below using a Watt bath, and then 10 vol.% H ₂ + 90 vol at.% N ₂ atmosphere and annealed at 700 ° C. by diffusing penetrate nickel plating to form Fe-Ni alloy layer (Ni-containing layer) on both sides. Subsequently, a tin plating bath was used for the steel sheet having the Ni-containing layer as the surface layer, and after Sn layers were formed on both sides with the Sn adhesion amount per one side shown in Table 2, reflow treatment was performed at a melting point of Sn or more, Plating layers were formed on both sides of the T4 original plate.

[Formation of film]
A steel plate with a plating layer is immersed in a 10 g / L sodium carbonate solution having a bath temperature of 30 ° C. and a pH of 11 or a sodium hydroxide aqueous solution, and an anodic electrolytic treatment is performed under the pretreatment conditions shown in Table 2 below. A tin oxide film was formed. Subsequently, the obtained steel plate with a tin oxide film was washed with water, and a 60 ° C. treatment solution (solvent: water) added with 100 μg / L of a tin phosphate treatment solution PF-K5102 manufactured by Nihon Parkerizing Co., Ltd. was used. The anodic electrolysis was performed under the electrolysis conditions (current density, immersion time, electrolysis time) shown in Table 2. Then, the obtained steel sheet with a tin oxide film was washed with water at 85 ° C. and dried at room temperature using a blower, thereby forming the film of the present invention on both surfaces of the steel sheet. Thereby, the test material of the steel plate for containers was produced. Then, about the produced test material of the steel plate for containers, paint adhesiveness and tin oxidation resistance were evaluated by the method mentioned later. The evaluation results are summarized in Table 3 below.

[Paint adhesion]
An epoxyphenol-based paint having an adhesion amount of 50 mg / dm ² was applied to the surface of the produced steel plate for containers, and then baked at 210 ° C. for 10 minutes. Next, 100 square grids (the area of 1 square is 1 mm ² ) are put into the steel plate for containers which has been coated and baked with a cutter knife, and then the tape is peeled off. evaluated. Practically, if the evaluation is 又 は or ○, it can be evaluated as having excellent paint adhesion.

A: 0.0% or more and less than 10.0% (equivalent to chromate treatment material)
○: 10.0% or more and less than 60.0% ×: 60% or more

[Tin oxidation resistance]
The container steel plate immediately after production (within one week after production) was stored for 2 weeks in an environment of a temperature of 50 ° C. and a relative humidity of 80%, and the coloration of the steel plate surface before and after that was evaluated. Specifically, b value was measured using SQ-2000 manufactured by Nippon Denshoku Industries Co., Ltd., and Δb value (post-test steel plate b value-pre-test steel plate b value) was evaluated according to the following evaluation criteria. And if evaluation was (circle), it evaluated as what is excellent in tin-oxidation resistance.

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

As is clear from the results shown in Tables 2 and 3, it was confirmed that all of the inventive examples were excellent in paint adhesion and tin oxidation resistance. On the other hand, the P adhesion amount of the tin phosphate coating is not within the range of 0.1 mg / m ² or more and 3.0 mg / m ² or less, or the reducing electricity amount of the tin oxide coating is 5.0 mC / In comparative examples with more than cm ² , the paint adhesion was poor. Moreover, tin oxide resistance was inferior in the comparative example in which the A value was 1.0 or more and the amount of reducing electricity of the tin oxide film was less than 1.5 mC / cm ² .

  ADVANTAGE OF THE INVENTION According to this invention, the steel plate for containers excellent in coating-material adhesiveness and tin-oxidation resistance, and its manufacturing method can be provided.

Claims (2)

A tinned steel sheet having a tinned layer on the surface;
A tin oxide film formed on the surface of the tin plating layer;
A tin phosphate film formed on the surface of the tin oxide film and containing 0.1 mg / m ² or more and 3.0 mg / m ² or less of tin phosphate as an amount of P;
With
When the tin oxide film was reduced in a 0.001N hydrogen bromide aqueous solution while sweeping the potential from the immersion potential to the base side, the -800 to -500 mV vs. saturated KCl-Ag / AgCl reference electrode Having a reduction current peak in the range of
A value defined by the following mathematical formula (1) is less than 1.0,
Container, characterized in that in the range amount of electricity required for reduction of the tin oxide film calculated from the potential curve is 2.60 mC / cm ² or more 5.0mC / cm ² or less - reduction current of the tin oxide film Steel plate.

Here, Q ₁ represents the amount of electricity required for the reduction of the tin oxide film having a reduction current peak in the range of −600 to −500 mV, and Q ₂ is a tin oxide having a reduction current peak on the base side from −600 mV. It represents the amount of electricity required to reduce the film. The tin oxide film is formed by subjecting the tin-plated steel sheet to an aqueous treatment in an aqueous solution having a pH in the range of 8 to 13 and subjecting the tin-plated steel sheet to an electrolytic treatment, followed by washing with water. A pre-processing step;
Immerse the tin-plated steel sheet after the pretreatment step in a phosphate aqueous solution at 1.0 second or more and 5.0 seconds or less, or immerse the tin-plated steel sheet after the pretreatment step in a phosphate aqueous solution, the tin-plated steel sheet 0.1 a / dm ² or more 10A / dm ² or less as an anode, by subjecting the electrolysis of 2.0 seconds or less than 0.1 seconds, phosphate film forming of forming the tin phosphate coating The manufacturing method of the steel plate for containers of Claim 1 characterized by including a step.

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