JP2005272871A - Method for manufacturing tin-plated steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stably manufacturing a tin-plated steel sheet, by establishing a technique for surely controlling a coating mass in a horizontal tin-plating line. <P>SOLUTION: When plating a steel sheet with tin by passing it in the horizontal tin-plating line having a plurality of plating cells and having a part of the cells energized, this manufacturing method includes controlling the final coating mass into a target range, by plating the steel sheet in an energized cell so as to acquire the previously calculated coating mass that includes both of the amount of tin which will dissolve in an unenergized cell placed in a downstream of the energized cell and the target coating mass. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a tin-plated steel sheet in a horizontal tin plating line using a horizontal plating tank in which a plurality of plating cells are arranged horizontally.

  As shown in FIG. 1, the structure of a general horizontal plating line is as follows. A steel plate (cover plate) 1 that has been degreased and pickled is first arranged horizontally in a plurality of plating cells 2a to 2j. Then, tin plating is applied to one side of the steel plate 1 facing the lower side. After that, the steel plate 1 plated with tin on one side is inverted, and then enters the horizontal plating tank 3 in which a plurality of plating cells 3a to 3j are arranged horizontally, and is placed on the lower side after the inversion. Tin plating is applied to the other surface of the steel plate 1 facing.

  This horizontal tin plating line uses a halogen bath or methanesulfonic acid (MSA) bath mainly composed of stannous chloride and acidic sodium fluoride, and these plating solutions can be operated at a high current density. Further, since the plating tank is horizontal and the structure is relatively simple, it is easy to control the passing of the steel plate, and it is suitable for producing a tin-plated steel plate at a high speed.

  Therefore, in the horizontal tin plating line, various tin-plated steel sheets with different tin-plating amounts are manufactured, and the number of plating cells is controlled by passing an electrolysis current according to the tin-plating amount and the plate feed speed. doing. For example, in FIG. 1, the cells 2a and 2b are energized among the lower ten plating cells 2a to 2j, and the cells 3c and 3d are energized among the upper ten plating cells 3a to 3j. Thus, the cell to be energized is selected, and the tin plating adhesion amount is mainly controlled. The plating solution 4 is circulated and supplied between each plating cell and the storage tank 5 via, for example, a pump.

  As described above, in the horizontal tin plating line, the plating adhesion amount is controlled by increasing or decreasing the number of energized cells. However, it is extremely difficult to obtain the desired plating adhesion amount. There were two problems.

Here, with respect to the control of the plating adhesion amount in electroplating, for example, Patent Documents 1 and 2 propose controlling the plating current as a plating condition.
JP 63-282296 A JP-A-64-17890

  However, even if the above general electroplating control is applied to the horizontal tin plating line, the effective effect is poor, and the control of the electroplating amount in the horizontal tin plating line is still fully realized. The current situation is not.

  Accordingly, an object of the present invention is to provide a method for stably producing a tin-plated steel sheet by establishing a technique for reliably controlling the amount of plating adhesion in a horizontal tin plating line.

  The inventors diligently studied the control of the amount of plating in the horizontal tin plating line, and no matter how the plating conditions in the plurality of plating cells constituting the horizontal tin plating line were adjusted, the amount of plating adhesion was controlled. This is because the steel sheet passes through the plating cell that is not energized in the horizontal tin plating line, and the main reason is that the plating layer formed on the steel sheet is dissolved by the plating solution. In consideration of the dissolution of the plating layer here, it was found that the amount of plating adhesion can be controlled even in the horizontal tin plating line, and the present invention has been completed.

That is, the gist configuration of the present invention is as follows.
(1) In a method for manufacturing a tin-plated steel sheet, which has a plurality of plating cells, and tin-plats through the steel sheet to a horizontal tin plating line in which some of the cells are energized.
The final tin plating adhesion amount is obtained by performing the tin plating with the plating adhesion amount in the energized cell as the amount obtained by adding the dissolution amount of tin plating in the non-energized cell downstream of the energization cell to the target tin plating adhesion amount in advance. Is controlled to be within a target range.

(2) The method for producing a tin-plated steel sheet according to (1) above, wherein the pH of the plating cell is 4 or less.

(3) The amount of tin plating dissolved in the non-energized cell: α (g / m ² ), the immersion time of the steel plate in the cell: t1 (s), and the pH of the plating solution in the cell: pH1 The method for producing a tin-plated steel sheet according to (1) or (2) above, wherein the method is obtained according to the following formula (1).
Α = (− 0.004 × pH1 + 0.0370) × t1 ---- (1)

(4) After applying tin plating to one side of a steel sheet in a horizontal tin plating line having a plurality of plating cells, the steel sheet is turned over while the plating solution is sprayed onto the steel sheet, and then the other side of the steel sheet is reversed. In the method for producing a tin-plated steel sheet in which the surface is tin-plated,
Add the plating adhesion amount in the current-carrying cell to the target tin-plating adhesion amount beforehand by adding the dissolution amount of tin plating in the non-energized cell downstream of the conduction cell and the dissolution amount of tin plating by spraying the plating solution. A method for producing a tin-plated steel sheet, characterized in that tin plating is performed as an amount, and a final tin plating adhesion amount is controlled within a target range.

(5) The method for producing a tin-plated steel sheet according to (4) above, wherein the pH of the plating cell is 4 or less.

(6) The amount of tin plating dissolved in the non-energized cell: α (g / m ² ), the immersion time of the steel plate in the cell: t 1 (s), and the pH of the plating solution in the cell: pH 1 The amount of tin plating dissolved β (g / m ² ) by the plating solution spray supply is calculated from the following formula (1), and the plating solution spray supply time: t2 and the pH of the plating solution supplied by spraying: pH2 The method for producing a tin-plated steel sheet according to the above (4) or (5), wherein the method is obtained according to the following formula (2).
Α = (− 0.004 × pH1 + 0.0370) × t1 ---- (1)
β = (− 0.0044 × pH2 + 0.0304) × t2 −−−− (2)

  According to the present invention, since a method for reliably controlling the amount of plating adhesion in a horizontal tin plating line is established, it is possible to stably provide a steel sheet having tin plating with a desired plating adhesion amount.

  Now, it is difficult to reliably control the amount of plating in the horizontal tin plating line, as described above, when the plated steel plate passes through the plating cell that is not energized, The main reason is that it is dissolved in the plating solution. Therefore, it is important to consider the dissolution of the plating layer here. Therefore, in the present invention, the tin plating is performed with the tin plating adhesion amount obtained by adding the tin plating dissolution amount in the non-energized cell downstream of the energization cell to the target tin plating adhesion amount in advance.

  In other words, taking the horizontal tin plating line shown in FIG. 1 as an example, the energization plating cells in this line are first plating cells 2a and 2b, and the plating cells 2c to 2j, 3a and 3b downstream thereof are Not energized. Accordingly, the amount of tin plating dissolved in the plating cells 2c to 2j, 3a, and 3b that are not energized is preliminarily added to the target tin plating adhesion amount in the upstream plating cells 2a and 2b. Tin plating is performed in the cells 2a and 2b. Similarly, in the subsequent steps, the amount of tin plating dissolved in the non-energized plating cells 3e to 3j downstream of the energizing plating cells 3c and 3d is preliminarily determined as the target tin plating in the upstream plating cells 3c and 3d. Tin plating is performed in the plating cells 3c and 3d with the tin plating adhesion amount added to the adhesion amount.

Thus, by adding the amount of tin plating dissolved in the non-energized cell that hinders tin plating adhesion amount control to the amount of plating adhered in the energized cell upstream of the non-energized cell in advance. Finally, it is possible to obtain a tin-plated steel sheet in which the amount of tin plating is controlled within a target range.
Here, the target range refers to a tin plating adhesion amount that is allowed and is in a lower limit range with respect to the target tin plating adhesion amount.

Here, the amount of tin plating dissolved in a non-energized cell was investigated by varying the pH of the plating solution in the cell and fixing the immersion time in the cell to 1 s. As shown in FIG. 2, the dissolution amount of tin plating in a cell that is not energized: α (g / m ² ) is correlated with the pH of the plating solution in the cell, and the result is shown in FIG. From the immersion time: t1 (s) and the pH of the plating solution in the cell: pH1, the following formula (1)
α = (− 0.004 × pH1 + 0.0370) × t1 ---- (1)
As required.

  Therefore, according to the above formula (1), the dissolution amount of the tin plating in the non-energized cell was obtained, and if there were a plurality of non-energized cells, the dissolution amount in each cell was totaled and thus obtained. What is necessary is just to add the amount of melt | dissolution beforehand to the plating adhesion amount in an upstream electricity supply cell.

According to the above formula (1), the amount of tin plating dissolved in a cell that is not energized is proportional to the pH of the plating solution in the cell, so the plating solution in the plating cell has the same pH. Is based on the result of adding the amount of tin plating dissolved in all non-energized cells downstream of the first energized cell (or group of cells) and adding this to the final target plating adhesion, The plating conditions may be adjusted for all energized cells.
On the other hand, when the pH of the plating solution in the plating cell is different, the energized cell (or cell group) and the non-energized cell (or cell group) located downstream of the cell are paired, and for each group, downstream What is necessary is just to adjust plating conditions based on the plating adhesion amount which added the total amount of dissolution of the tin plating in each non-energized cell to the target plating adhesion amount in the upstream energization cell (or cell group) .

  In the horizontal tin plating line, as shown in FIG. 1, the steel plate 1 plated on one surface in the lower horizontal plating tank 2 is inverted, and then the upper horizontal plating tank 3. Then, tin plating is performed on the other surface of the steel sheet 1 facing downward after the reversal, but in the reversal process of the steel sheet, as shown in FIG. In general, the plating solution is mainly sprayed from the nozzle 6.

  Thus, when the steel plate reversal process is downstream of the energized plating cell, tin plating dissolves even in the spraying process by spray supply of this plating solution. It is necessary to consider. Therefore, in addition to the amount of tin plating dissolved in the non-energized cell downstream of the above-described energized cell, the amount of tin plating dissolved by spray supply of the plating solution was added in advance to the target tin plating adhesion amount, It is important to control the final tin plating adhesion amount within the target range by performing tin plating with the tin plating adhesion amount.

Here, the amount of tin plating dissolved by spray supply was investigated by varying the pH of the plating solution supplied by spraying and fixing the spray supply time of the plating solution to 1 s. As shown in FIG. 4, the dissolution amount β (g / m ² ) of tin plating by spray supply correlates with the pH of the plating solution supplied by spray supply, and the plating solution spray supply time t 2 (s) And the pH of the plating solution supplied by spraying: From pH 2, the following formula: β = (− 0.0044 × pH 2 +0.0304) × t 2
As required.

  Then, the amount of tin plating dissolved by spray supply, obtained in accordance with the above equation, together with the amount of tin plating dissolved in the non-energized cell downstream of the above-described energized cell, as well as the amount of plating deposited in the upstream energized cell If it is added in advance, it becomes possible to control the tin plating adhesion amount within the target range.

In the horizontal tin plating line (plating cell length: 2500 mm each) shown in FIG. 5, tin plating is applied to the front and back surfaces of the tin plate (low carbon steel plate) under the following conditions as shown in Table 1. As shown in Table 3, correction was made in consideration of the dissolution amount of tin plating in the non-energized cells shown in Table 2. Table 4 shows the results of the investigation on the amount of coating on the tin-plated steel sheet thus obtained. Further, as a comparison, the amount of plating adhesion was similarly investigated in the case where no correction was made in consideration of the dissolution amount of tin plating in a non-energized cell. In this comparative example, the dissolution amount by the non-energized cell is shown in Table 5, and the measured plating adhesion amount is shown in Table 6. In addition, in the inversion process of the steel plate, pure water was supplied to prevent the steel plate from drying.
Plating solution composition:
First tin chloride: 75g / l
Sodium fluoride: 25g / l
Potassium hydrogen fluoride: 55 g / l
Sodium chloride: 45g / l
Sn ²⁺ : 36g / l
Sn ⁴⁺ : 1g / l
pH: 3.5
Additive (surfactant): 1-2 g / l
Temperature: 65 ℃
Current density: 60 to 70 A / dm ²
Feeding speed: 3333 mm / s (200m / min)

In the horizontal tin plating line (plating cell length: 2500 mm each) shown in FIG. 6, tin plating is applied to the front and back surfaces of the tin plate (low carbon steel plate) under the following conditions under the target plating adhesion amount shown in Table 7. As shown in Table 9, corrections were made in consideration of the dissolution amount of tin plating in a non-energized cell shown in Table 8 and the dissolution amount of tin plating by spray supply of the plating solution. Table 10 shows the results of the investigation on the amount of coating on the tin-plated steel sheet thus obtained. Further, as a comparison, the amount of plating adhesion was similarly investigated in the case where no correction was made in consideration of the amount of tin plating dissolved in a non-energized cell. Table 11 shows the dissolution amount of the non-energized cell in this comparative example, and Table 12 shows the measured plating adhesion amount.
Plating solution composition:
First tin chloride: 75g / l
Sodium fluoride: 25g / l
Potassium hydrogen fluoride: 55 g / l
Sodium chloride: 45g / l
Sn ²⁺ : 36g / l
Sn ⁴⁺ : 1g / l
Additive (surfactant): 1-2 g / l
pH: 3.5
Temperature: 65 ℃
Current density: 60 to 70 A / dm ²
Feeding speed: 3333 mm / s (200m / min)
PH of spray supply plating solution during reversal: 3.5
Inversion plating spray supply time: 1.14s

In the horizontal tin plating line (plating cell length: 2500 mm each) shown in FIG. 5, tin plating is performed on the front and back surfaces of the tin plate (low carbon steel plate) under the following conditions as shown in Table 13 As shown in Table 15, correction was made in consideration of the dissolution amount of tin plating in the non-energized cell shown in Table 14. Table 16 shows the results of investigating the coating adhesion amount of the tin-plated steel sheet thus obtained. Further, as a comparison, the amount of plating adhesion was similarly investigated in the case where no correction was made in consideration of the amount of tin plating dissolved in a non-energized cell. In this comparative example, the dissolution amount by the non-energized cell is shown in Table 17, and the actually measured plating adhesion amount is shown in Table 18. In addition, in the inversion process of the steel plate, pure water was supplied to prevent the steel plate from drying.
Plating solution composition:
Methanesulfonic acid: 20-50ml / l
Sn ²⁺ : 20-30g / l
Brightener: 40-60ml / l
Antioxidant (antioxidation of tin ion): 15-25ml / l
H ₂ SO ₄ (96 mass%): 0.5-1.6ml / l
pH: 1.0
Current density: 60 to 70 A / dm ²
Feeding speed: 3333 mm / s (200m / min)

In the horizontal tin plating line (plating cell length: 2500 mm each) shown in FIG. 6, on the front and back surfaces of the tin plate (low carbon steel plate) under the target plating adhesion amount shown in tin plating table 19 under the following conditions: As shown in Table 21, corrections were made in consideration of the dissolution amount of tin plating in a non-energized cell shown in Table 20 and the dissolution amount of tin plating by spray supply of the plating solution. Table 22 shows the results of investigating the amount of coating on the tin-plated steel sheet thus obtained. Further, as a comparison, the amount of plating adhesion was similarly investigated in the case where no correction was made in consideration of the amount of tin plating dissolved in a non-energized cell. Table 23 shows the dissolution amount of the non-energized cell in this comparative example, and Table 24 shows the actually measured plating adhesion amount.
Plating solution composition:
Methanesulfonic acid: 20-50ml / l
Sn ²⁺ : 20-30g / l
Brightener: 40-60ml / l
Antioxidant (antioxidation of tin ion): 15-25ml / l
H ₂ SO ₄ (96 mass%): 0.5-1.6ml / l
pH: 1.0
Current density: 60 to 70 A / dm ²
Feeding speed: 3333 mm / s (200m / min)
PH of spray supply plating solution during reversal: 1.0
Inversion plating spray supply time: 1.14s

  As described above, in the examples, the amount of plating adhesion could be reliably controlled in the horizontal plating line. On the other hand, in the comparative example, control of the amount of plating was insufficient due to dissolution by a non-energized cell or plating solution spray.

  Although the present invention has been described with respect to the halogen bath and the MSA bath, the present invention can be applied to a horizontal tin plating method using a ferrostan bath (phenol sulfonic acid tin bath) or an alkaline bath (sodium stannate or caustic soda bath). Is possible.

It is a figure which shows the structure of a horizontal type | mold tin plating line. It is a figure which shows the dissolution rate of the tin plating in the cell which is not supplying with electricity. It is a figure which shows another structure of a horizontal type | mold tin plating line. It is a figure which shows the melt | dissolution rate of the tin plating by the spray supply of a plating solution. It is a figure which shows the structure of the horizontal type | mold tin plating line used for Example 1 and 2. FIG. It is a figure which shows the structure of the horizontal tin-plating line used for Example 2 and 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 2, 3 Horizontal type plating tank 2a-2j, 3a-3j Plating cell 4 Plating solution 5 Storage tank

Claims (6)

In the method for producing a tin-plated steel sheet, which has a plurality of plating cells, and in which a tin plate is plated through a steel sheet to a horizontal tin plating line energized through some of the cells,
The final tin plating adhesion amount is obtained by performing the tin plating with the plating adhesion amount in the energized cell as the amount obtained by adding the dissolution amount of tin plating in the non-energized cell downstream of the energization cell to the target tin plating adhesion amount in advance. Is controlled to be within a target range.   The method for producing a tin-plated steel sheet according to claim 1, wherein the pH of the plating cell is 4 or less. The dissolution amount of tin plating in the non-energized cell: α (g / m ² ), the immersion time of the steel plate in the cell: t 1 (s) and the pH of the plating solution in the cell: pH 1 The method for producing a tin-plated steel sheet according to claim 1 or 2, wherein the method is obtained according to (1).
Α = (− 0.004 × pH1 + 0.0370) × t1 ---- (1) After applying tin plating to one side of a steel sheet in a horizontal tin plating line having a plurality of plating cells, the front and back of the steel sheet are reversed while supplying a plating solution to the steel sheet, and then tin is applied to the other side of the steel sheet. In the method for producing a tin-plated steel sheet to be plated,
Add the plating adhesion amount in the current-carrying cell to the target tin-plating adhesion amount beforehand by adding the dissolution amount of tin plating in the non-energized cell downstream of the conduction cell and the dissolution amount of tin plating by spraying the plating solution. A method for producing a tin-plated steel sheet, characterized in that tin plating is performed as an amount, and a final tin plating adhesion amount is controlled within a target range.   The method for producing a tin-plated steel sheet according to claim 4, wherein the plating cell has a pH of 4 or less. The dissolution amount of tin plating in the non-energized cell: α (g / m ² ), the immersion time of the steel plate in the cell: t 1 (s) and the pH of the plating solution in the cell: pH 1 In accordance with (1), the dissolution amount β (g / m ² ) of tin plating by spray supply of the plating solution is calculated from the following formula using the spray supply time of the plating solution: t2 and the pH of the plating solution supplied: pH2. The method for producing a tin-plated steel sheet according to claim 4 or 5, wherein the method is obtained according to (2).
Α = (− 0.004 × pH1 + 0.0370) × t1 ---- (1)
β = (− 0.0044 × pH2 + 0.0304) × t2 −−−− (2)

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