JP6361628B2 - Manufacturing method of steel plate for containers - Google Patents

Description

  The present invention relates to a method for producing a steel plate for containers.

  As a steel plate for containers, a tin-plated steel plate conventionally referred to as “blink” has been widely used. In such a tin-plated steel plate, the surface of the tin-plated surface is usually obtained by immersing the steel plate in an aqueous solution containing a hexavalent chromium compound such as dichromic acid, or by performing a chromate treatment such as performing an electrolytic treatment in this solution. A chromate film is formed on the surface.

  However, in light of recent environmental problems, movements for restricting the use of Cr have progressed in various fields, and several treatment techniques for replacing chromate treatment have been proposed for steel plates for containers. For example, Patent Documents 1 and 2 disclose techniques for forming a film containing Ti on the surface of a steel sheet.

JP 2013-119647 A JP2013-127095A JP 2005-118639 A

  By the way, in order to form a film containing Ti, when a cathode electrolytic treatment is continuously performed for a long time in a treatment liquid containing hexafluorotitanic acid and / or a salt thereof as a Ti component, In some cases, the amount of Ti-converted adhesion (Ti adhesion amount) gradually decreases. In this case, it becomes difficult to obtain a desired Ti mass film thickness, which is not suitable for practical use.

For example, Patent Document 1 discloses a method of immersing metal Ti in a processing solution, and Patent Document 2 discloses an anode as a method in which the amount of Ti adhesion does not decrease even when cathodic electrolysis is performed continuously for a long time. A method using metal Ti is disclosed.
Both methods aim to prevent a decrease in Ti concentration in the treatment liquid using metal Ti, but in practice, a stable oxidized Ti film is formed on the surface of metal Ti over time. Since it is formed, sufficient Ti may not be supplied. For this reason, it is necessary to remove the Ti oxide film as appropriate, which causes a decrease in productivity.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing a steel plate for containers that can suppress a decrease in the amount of Ti adhesion even when cathodic electrolysis is performed continuously for a long time. To do.

  As a result of intensive investigations to achieve the above object, the present inventors have added a specific additive in the treatment liquid, so that the amount of Ti adhesion can be reduced even when performing cathodic electrolysis continuously for a long time. The present inventors have found that the decrease can be suppressed and completed the present invention.

That is, the present invention provides the following [1] to [4].
[1] A plating layer including at least a part of the surface of the steel plate including at least one layer selected from the group consisting of a Ni layer, a Sn layer, a Ni—Fe alloy layer, a Fe—Sn—Ni alloy layer, and a Fe—Sn alloy layer. A coating containing Ti on the surface of the plated steel sheet on the plating layer side by subjecting the coated steel sheet to cathodic electrolysis in a treatment liquid containing hexafluorotitanic acid and / or a salt thereof. to form a method of manufacturing a container for a steel sheet, F in the treatment solution by the cathode electrolytic treatment ^- when increasing the concentration, the addition of titanium hydroxide during the treatment solution, the production of containers for steel Method.
[2] The content of the hexafluorotitanic acid and / or salt thereof in the treatment liquid is 0.004 to 0.400 mol / L in terms of hexafluorotitanate ion (TiF ₆ ²⁻ ). The method for producing a steel plate for containers according to the above [1].
[3] The treatment liquid further contains a Ni component, and the content of the Ni component in the treatment liquid is 0.002 to 0.040 mol / L in terms of Ni ions (Ni ²⁺ ). The manufacturing method of the steel plate for containers as described in said [1] or [2].
At least selected from the group consisting of ^- [4] the processing liquid, further, K ^+, and at least one cation selected from the group consisting of Na ⁺ and _{^{NH 4 +, SO 4 2-,}} NO 3 - and Cl One of the above [1] to [3], which contains a salt composed of a combination with one kind of anion, and the content of the salt in the treatment liquid is 0.1 to 100 in terms of a molar ratio to Ti. The manufacturing method of the steel plate for containers of description.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the steel plate for containers which can suppress the reduction | decrease of Ti adhesion amount also when performing a cathodic electrolysis process continuously for a long time can be provided.

[Outline of the present invention]
As described above, when the cathodic electrolytic treatment is continuously performed for a long time in a treatment liquid containing hexafluorotitanic acid and / or a salt thereof as a Ti component, the Ti adhesion amount of the obtained film may gradually decrease. . This phenomenon can be explained as follows.

First, the cathodic electrolysis treatment causes a pH increase associated with hydrogen generation on the surface of the steel sheet (see the following formula (1)). As a result, pH is increased at the interface between the steel sheet and the processing liquid, hexafluoro titanic acid ion (fluoro titanic acid ion) in the treatment liquid (TiF ₆ ^2-) is de-F ^- the performed while titanium hydroxide ( Ti (OH) ₄ ) is formed (see the following formula (2)). This titanium hydroxide precipitates on the surface of the steel sheet, and then undergoes dehydration condensation by washing and drying, and changes to a Ti-containing film.
2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻ (1)
TiF ₆ ²⁻ + 4OH ⁻ → Ti (OH) ₄ + 6F ⁻ (2)

However, if F ⁻ generated during the titanium hydroxide formation reaction (see the above formula (2)) is accumulated in the treatment liquid by electrolysis for a long time, the titanium hydroxide formation reaction rate decreases. For this reason, when it processes on the same electrolysis conditions, the production amount of titanium hydroxide decreases and the Ti adhesion amount of a film | membrane reduces.

Therefore, when performing cathodic electrolytic treatment continuously in a treatment solution containing a Ti component (hexafluorotitanic acid and / or its salt) for a long time, It is necessary to remove or trap the F ⁻ of the. Further, the Ti component in the treatment liquid is removed from the treatment liquid as a film by continuous treatment, and therefore it is preferable to replenish appropriately.

In view of the above mechanism, the present inventors have added titanium hydroxide (Ti (OH) ₄ ) to the treatment liquid during continuous operation for a long time. This promotes the reverse reaction of the above formula (2), captures F ⁻ in the treatment liquid, and generates hexafluorotitanate ions (TiF ₆ ²⁻ ), thereby forming Ti adhesion on the film. The present inventors have found that the decrease in the amount can be suppressed and completed the present invention.

In addition, the present inventors expect the reaction represented by the following formulas (3) and (4), and instead of titanium hydroxide (Ti (OH) ₄ ), for example, Patent Document 3 discloses “fluorine”. An attempt was made to use metatitanic acid (TiO (OH) ₂ ) disclosed as “ion recovery material” (in Patent Document 3, it is described that “fluorine ion recovery material” consists of “titanium hydroxide gel”. However, considering that it is manufactured from “TiOSO ₄ .xH ₂ O”, what is actually obtained is not titanium hydroxide (Ti (OH) ₄ ) but metatitanic acid (TiO (OH ) ₂ )). However, metatitanic acid was not completely dissolved in the treatment liquid, and the effect of suppressing a decrease in the amount of Ti adhered to the film was not sufficiently obtained.
TiO (OH) ₂ + 2F ⁻ → TiOF ₂ + 2OH ⁻ (3)
TiOF ₂ + 4F ⁻ + H ₂ O → TiF ₆ ²⁻ + 2OH ⁻ (4)

  The above mechanism is an estimation, and it is assumed that the mechanism other than the above mechanism is within the scope of the present invention.

  In the following, first, a steel plate for containers obtained by the method for manufacturing a steel plate for containers of the present invention (hereinafter also referred to as “the manufacturing method of the present invention”) (hereinafter also referred to as “the steel plate for containers of the present invention” for convenience). After the description, the production method of the present invention will be described in detail.

[Steel plate for containers]
The steel plate for containers of the present invention generally has a plated steel plate and a film disposed on the surface of the plated steel plate on the plating layer side. Hereinafter, specific embodiments of the plated steel sheet and the coating will be described in detail.

[Plated steel sheet]
The plated steel sheet includes a steel sheet and a plating layer that covers at least a part of the surface of the steel sheet.
As a raw steel plate, a general steel plate for cans can be used. The plating layer may be a continuous layer or a discontinuous island shape. Moreover, the plating layer should just be provided in the at least single side | surface of the steel plate, and may be provided in both surfaces. The plating layer can be formed by a known method according to the contained metal element.
Below, the suitable aspect of a steel plate and a plating layer is explained in full detail.

<steel sheet>
The kind of steel plate is not particularly limited. Usually, a steel plate (for example, a low carbon steel plate or an ultra low carbon steel plate) used as a container material can be used. The manufacturing method and material of the steel plate are not particularly limited. It is manufactured through processes such as hot rolling, pickling, cold rolling, annealing, temper rolling and the like from a normal billet manufacturing process.
If necessary, a steel sheet having a nickel-containing layer (Ni-containing layer) formed on the surface thereof may be used, and a plated layer including an Sn layer described later may be formed on the Ni-containing layer. By performing Sn plating using a steel sheet having a Ni-containing layer, a plating layer containing island-shaped Sn can be formed. As a result, weldability is improved.
The Ni-containing layer only needs to contain nickel. For example, a Ni plating layer (Ni layer), a Ni—Fe alloy layer, and the like can be given.
The method for applying the Ni-containing layer to the steel plate is not particularly limited. For example, a known method such as electroplating can be used. Moreover, when providing a Ni-Fe alloy layer as a Ni-containing layer, Ni can be diffused in the steel by annealing after applying Ni on the steel sheet surface by electroplating or the like, thereby forming a Ni-Fe alloy layer.
The amount of Ni deposited in the Ni-containing layer is not particularly limited, and is preferably 50 to 2000 mg / m ² as the amount of metal Ni converted on one side. If it is in the said range, it will become advantageous also in terms of cost.
The Ni adhesion amount can be measured by surface analysis with fluorescent X-rays. In this case, a calibration curve related to the Ni adhesion amount is specified in advance using a Ni adhesion sample with a known Ni adhesion amount, and the Ni adhesion amount is relatively specified using the calibration curve. However, when the film to be described later contains Ni, it is difficult to measure only the amount of Ni deposited in the Ni-containing layer by the surface analysis using the fluorescent X-ray. In that case, the Ni adhesion amount in the Ni-containing layer can be obtained by subtracting the Ni adhesion amount contained in the film described later from the Ni adhesion amount obtained by fluorescent X-rays.

<Plating layer>
The plated steel sheet includes a plated layer including at least one layer selected from the group consisting of a Ni layer, a Sn layer, a Ni—Fe alloy layer, a Fe—Sn—Ni alloy layer, and a Fe—Sn alloy layer on at least a part of the surface of the steel plate. Have The plating layer only needs to be provided on at least one side of the steel plate, and may be provided on both sides. Moreover, a plating layer is a layer which covers at least one part on the steel plate surface, A continuous layer may be sufficient and a discontinuous island shape may be sufficient as it.
The Sn adhesion amount per one side of the steel sheet of the plating layer is preferably 0.1 to 15.0 g / m ² . When the Sn adhesion amount is within the above range, the corrosion resistance of the steel plate for containers is more excellent. 0.2-15.0 g / m < ² > is more preferable.
Note that the Sn adhesion amount can be measured by surface analysis using fluorescent X-rays. In the case of fluorescent X-rays, a calibration curve relating to the Sn amount is specified in advance using a Sn adhesion amount sample with a known Sn amount, and the Sn amount is relatively specified using the calibration curve.

As a plating layer, in addition to a plating layer composed of a Sn layer that is a plating layer of a single tin obtained by plating Sn, the lowermost layer of the Sn layer obtained by heating and melting Sn by means of energization heating after Sn plating ( A plating layer in which a part of the Fe—Sn alloy layer is formed on the (Sn layer / steel plate interface) is also exemplified.
Moreover, as a plating layer, Sn plating is performed on a steel sheet having a Ni-containing layer on the surface, and Sn is heated and melted by current heating or the like, and is formed on the lowermost layer (Sn layer / steel sheet interface) of the Sn layer. Examples thereof include a plating layer in which an Fe—Sn—Ni alloy layer, an Fe—Sn alloy layer, etc. are partially formed.
In the present invention, the aforementioned Ni-containing layer (Ni layer, Ni—Fe alloy layer) is also included in the plated layer of the plated steel sheet.

Examples of the method for producing the plating layer include a known method (for example, an electroplating method or a method of plating by immersing in molten Sn).
For example, a phenol sulfonic acid Sn plating bath, a methane sulfonic acid Sn plating bath, or a halogen-based Sn plating bath is used, and Sn is electroplated on the surface of the steel sheet so that the adhesion amount per one surface becomes a predetermined amount. Thereafter, a heat melting treatment is performed at a temperature equal to or higher than the melting point of Sn (231.9 ° C.) to alloy the lowermost layer (Sn layer / steel plate interface) of the Sn single layer (Sn layer / steel plate interface) to form the Fe—Sn alloy layer. The formed plating layer can be manufactured. When the heat melting treatment is omitted, a Sn single plating layer (Sn layer) can be manufactured.
In addition, when the steel sheet has a Ni-containing layer on its surface, the lowermost layer (Sn layer / steel sheet interface) of the plating layer of Sn alone (Sn layer) is obtained by performing a heat melting treatment after Sn plating on the Ni-containing layer. Are alloyed to form an Fe—Sn—Ni alloy layer, an Fe—Sn alloy layer, or the like.

[Coating]
Next, the film | membrane arrange | positioned on the surface by the side of the plating layer of the plated steel plate mentioned above is demonstrated. The film is generally a film containing Ti (titanium element), and is formed using a treatment liquid described later.

<Ti>
The coating preferably has a Ti equivalent adhesion amount (hereinafter also referred to as “Ti adhesion amount”) per side of the plated steel sheet of 2.5 to 30.0 mg / m ² , and 5.0 to 30.0 mg. / M ² is more preferable, and 7.0 to 30.0 mg / m ² is more preferable.

<Ni>
The film may further contain Ni (nickel element). In this case, the coating preferably has an Ni conversion amount (hereinafter also referred to as “Ni adhesion amount”) of 0.1 to 20.0 mg / m ² per side of the plated steel sheet, more preferably 15.0 mg / m ^2, more preferably 0.1 to 10.0 mg / m ^2.

  Ti, Ni, and the like in the film are included as various titanium compounds and nickel compounds, respectively, and the types and aspects of these compounds are not particularly limited.

Ti adhesion amount and Ni adhesion amount are measured by surface analysis using fluorescent X-rays.
Note that the fluorescent X-ray analysis is performed, for example, under the following conditions.
Apparatus: X-ray fluorescence analyzer System 3270 manufactured by Rigaku Corporation
・ Measurement diameter: 30 mm
・ Measurement atmosphere: Vacuum ・ Spectrum: Ti-Kα, Ni-Kα
・ Slit: COARSE
-Spectral crystal: TAP
The peak count numbers of Ti-Kα and Ni-Kα in the fluorescent X-ray analysis of the film measured under the above conditions are used. Using a standard sample with a known adhesion amount, a calibration curve relating to the Ti adhesion amount and the Ni adhesion amount is specified in advance, and the Ti adhesion amount and the Ni adhesion amount are relatively determined using the calibration curve.

However, when the plating layer contains Ni, it is difficult to measure only the Ni adhesion amount contained in the film by the surface analysis using the fluorescent X-ray.
In that case, the amount of Ni contained in the coating is obtained by using both cross-sectional observation with a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and glow discharge emission analysis. And the amount of Ni contained in the plating layer can be distinguished.
Specifically, the cross section of the coating and the plating layer is exposed by focused ion beam (FIB) processing, and the thickness of the coating is calculated from cross-sectional observation by SEM or TEM. Next, the relationship between the sputtering depth and the sputtering time by glow discharge emission analysis is obtained. Thereafter, the integrated value of emission count by Ni element in the glow discharge emission analysis up to the sputtering time corresponding to the thickness of the film is obtained. From the integrated emission count value of the Ni element, the Ni adhesion amount can be obtained using a calibration curve obtained in advance.
Here, the calibration curve is created by the following method.
First, glow discharge emission analysis is performed on a plurality of samples having a coating film containing Ni on a plating layer not containing Ni and having different Ni adhesion amounts, and a count integrated value up to a sputtering time at which no emission count due to Ni element is detected is obtained. . Next, the Ni adhesion amount of these samples is obtained by surface analysis using fluorescent X-rays. In this way, a calibration curve between the Ni count integrated value and the Ni adhesion amount by glow discharge emission analysis is created.

[Manufacturing method of steel plate for containers]
Next, the manufacturing method (the manufacturing method of this invention) of the steel plate for containers of this invention is demonstrated.
The production method of the present invention is a method comprising at least a film forming step described later.

[Film formation process]
In the film forming step, the plated steel sheet is immersed in a treatment liquid described below (hereinafter also referred to as “treatment liquid of the present invention” for convenience), and the plated steel sheet is subjected to cathodic electrolytic treatment in the treatment liquid of the present invention. Is a step of forming the above-described film on the surface of the plated steel sheet on the plating layer side.
Hereinafter, the treatment liquid of the present invention used, the conditions of the cathode electrolytic treatment, and the like will be described in detail.

<Processing liquid>
The treatment liquid of the present invention contains a Ti component (Ti compound) for supplying Ti (titanium element) to the above-described film.
The Ti component includes titanium hydrofluoric acid (H ₂ TiF ₆ ) and / or a salt thereof. Examples of the titanium hydrofluoric acid salt include potassium hexafluorotitanate (K ₂ TiF ₆ ), sodium hexafluorotitanate (Na ₂ TiF ₆ ), and ammonium hexafluorotitanate ((NH ₄ ) ₂ TiF). ₆ ).
The content of titanium hydrofluoric acid and / or a salt thereof in the treatment liquid of the present invention is preferably 0.004 to 0.400 mol / L in terms of hexafluorotitanate ion (TiF ₆ ²⁻ ), 0.020 to 0.200 mol / L is more preferable.

Further, the treatment liquid of the present invention can contain a Ni component (Ni compound) for supplying Ni (nickel element) to the above-described film.
As the Ni component is not particularly limited, nickel sulfate (NiSO _4), nickel sulfate hexahydrate, nickel chloride (NiCl _2), etc. nickel chloride hexahydrate and the like.
The content of the Ni component in the treatment liquid of the present invention is not particularly limited, but is 0.002 to 0.040 mol / L, preferably 0.004 to 0.020 mol / L, in terms of Ni ion (Ni ²⁺ ). L is more preferable.

Further, the treatment liquid of the present invention, K ^+, and at least one cation selected from the group consisting of Na ⁺ and _{^{NH 4 +, SO 4 2-,}} NO 3 - and Cl ^- at least one selected from the group consisting of You may contain the salt (conducting aid) which consists of a combination with a seed | species anion.
Content of the said salt (conducting aid) in the processing liquid of this invention is 0.1-100 in the molar ratio with respect to Ti, for example.
When the treatment liquid of the present invention contains the salt, the liquid resistance of the treatment liquid can be reduced, and for example, a film can be formed with a relatively high current density.

As the solvent for the treatment liquid of the present invention, water is usually used, but an organic solvent may be used in combination.
Although the pH of the processing liquid of this invention is not specifically limited, pH 2.0-5.0 are preferable. Within this range, the treatment time can be shortened and the stability of the treatment liquid is excellent. For adjusting the pH, a known acid component (for example, phosphoric acid, sulfuric acid) or an alkali component (for example, sodium hydroxide, aqueous ammonia) can be used.
The treatment liquid of the present invention may contain a surfactant such as sodium lauryl sulfate or acetylene glycol as necessary. Further, from the viewpoint of the stability of the adhesion behavior over time, the treatment liquid of the present invention may contain a condensed phosphate such as pyrophosphate.
20-80 degreeC is preferable and, as for the liquid temperature of the processing liquid of this invention, 40-60 degreeC is more preferable.

<Cathode electrolysis treatment>
20.0-100.0 A / dm < ² > is preferable, and the electrolysis current density (current density) at the time of performing a cathode electrolytic treatment has more preferable 25.0-100.0 A / dm < ² >, 30.0-100.0 A / Dm ² is more preferable. If the current density is within the above range, Ti and Ni in the film to be formed will be in appropriate amounts, and the OH ⁻ ion concentration at the steel plate interface will be increased to promote the hydrolysis reaction of TiF ₆ ²⁻ ions. Then, the cross-linking of the film by subsequent dehydration condensation proceeds efficiently, the film becomes high molecular weight, and various performances are excellent.
The energization time for the cathodic electrolysis treatment is preferably 0.01 to 5 seconds, and more preferably 0.03 to 2 seconds, for the same reason as described above.
The quantity of electricity (unit: C / dm ² ) during cathodic electrolysis is the product of the current density and the energization time, and is appropriately set.

  In addition, when performing cathodic electrolysis processing continuously for a long time, the processing time (continuous electrolysis processing time) is 2 to 24 hours, for example.

<Titanium hydroxide and its addition>
When the cathodic electrolysis is performed continuously for a long period of time, the F ⁻ concentration in the treatment liquid of the present invention is monitored with an F ion meter or the like during the cathodic electrolysis.
When the cathodic electrolysis is performed and the F ⁻ concentration in the treatment liquid of the present invention is increased from a predetermined value such as a value before starting the cathodic electrolysis, for example, in the treatment liquid of the present invention. To this is added titanium hydroxide (Ti (OH) ₄ ). That is, F ⁻ in the treatment liquid of the present invention is captured and hexafluorotitanate ions (TiF ₆ ²⁻ ) are generated. Thus, a decrease in the amount of Ti adhered to the film is suppressed.

  As the titanium hydroxide, a commercially available product may be used, or a Ti compound (for example, titanium tetrachloride, titanium sulfate, titanium alkoxide, titanyl ammonium oxalate, potassium titanyl oxalate dihydrate, titanium lactate, etc.) You may prepare from the neutralization reaction with alkalis (for example, sodium hydroxide, potassium hydroxide, ammonia, etc.).

For example, when preparing titanium hydroxide by neutralization reaction of titanium sulfate and potassium hydroxide, the reaction formula is represented by the following formula (5). In this case, the salt (K ₂ SO ₄ ) obtained together with titanium hydroxide corresponds to the above-described salt (conducting aid) that may be contained in the treatment liquid of the present invention. .
Ti (SO ₄ ) ₂ + 4KOH → Ti (OH) ₄ + 2K ₂ SO ₄ (5)

Titanium hydroxide (Ti (OH) ₄ ) is very unstable and easily changes to metatitanic acid (TiO (OH) ₂ ) (see the following formula (6)). It is preferable to prepare immediately before the addition and to add immediately after the preparation.
Ti (OH) ₄ → TiO (OH) ₂ + H ₂ O (6)

<Washing and drying>
From the viewpoint of reducing F contained in the film, it is preferable to perform a water washing treatment after the cathodic electrolysis treatment. The method for the water washing treatment is not particularly limited. For example, when manufacturing by a continuous line, the method of providing a water-washing tank after a process liquid tank and immersing continuously in water after a cathodic electrolysis process etc. are mentioned. As for the temperature (water temperature) of the water used for a water-washing process, 40-90 degreeC is preferable.
At this time, the washing time is preferably more than 0.5 seconds and more preferably 1.0 to 5.0 seconds because the effect of the washing treatment is more excellent.
Further, drying may be performed in place of the water washing treatment or after the water washing treatment. The temperature and method for drying are not particularly limited. For example, a normal dryer or an electric furnace can be applied. The temperature during the drying treatment is preferably 100 ° C. or lower.

[Pretreatment process]
The manufacturing method of this invention may be equipped with the pre-processing process demonstrated below before the film formation process mentioned above.
The pretreatment step is a step of subjecting the plated steel plate to cathodic electrolysis in an alkaline aqueous solution (particularly, an aqueous sodium carbonate solution).
Usually, when the plating layer is formed, its surface is oxidized to form a tin oxide. By subjecting this plated steel sheet to cathodic electrolysis, unnecessary tin oxide can be removed and the amount of tin oxide can be adjusted.
Examples of the solution used for the cathodic electrolysis in the pretreatment step include an alkaline aqueous solution (for example, an aqueous sodium carbonate solution). The concentration of the alkaline component (for example, sodium carbonate) in the alkaline aqueous solution is not particularly limited, but is preferably 5 to 15 g / L, more preferably 8 to 12 g / L from the viewpoint that removal of tin oxide proceeds more efficiently. preferable.
The temperature of the alkaline aqueous solution during the cathodic electrolysis is not particularly limited, but is preferably 40 to 60 ° C. The electrolysis conditions (current density, electrolysis time) of the cathodic electrolysis are appropriately adjusted. In addition, you may perform a water washing process after a cathode electrolytic process as needed.

  The steel plate for containers of the present invention obtained by the production method of the present invention is used, for example, for the production of 2-piece can bodies and 3-piece can bodies such as food cans and beverage cans and lids.

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

<Manufacture of plated steel sheets>
A plated steel sheet was produced by the following method.
First, a steel plate (T4 original plate) having a thickness of 0.22 mm is electrolytically degreased, and a nickel plating layer is formed on both sides with a Ni adhesion amount per one side shown in Table 1 using a Watt bath, and then 10 vol.% H ₂ +90 vol. An Ni—Fe alloy layer (Ni-containing layer) was formed on both surfaces by annealing at 700 ° C. in a .N ₂ atmosphere to diffuse and infiltrate the nickel plating. Next, an Sn plating bath was used to form Sn layers on both sides with the Sn adhesion amount per one side shown in Table 1. Thereafter, a heat melting treatment was performed at a melting point of Sn or higher, and plating layers were formed on both surfaces of the T4 original plate. In this way, a plating layer composed of Ni—Fe alloy layer / Fe—Sn—Ni alloy layer / Sn layer was formed in order from the lower layer side.

<Manufacture of steel plates for containers>
The steel plate for containers was produced through the pre-processing process shown below and a film formation process.

<< Pretreatment process >>
First, the plated steel sheet was immersed in an aqueous sodium carbonate solution having a bath temperature of 50 ° C. and 10 g / L, and was subjected to cathodic electrolysis under the condition that the electric quantity density was 15 C / dm ² .

<Film formation process>
Next, with respect to the plated steel sheet that has undergone the pretreatment process, after washing with water, using the treatment liquid (solvent: water) having the composition shown in Table 1 adjusted to pH 4.0, the conditions shown in Table 1 were used. Cathodic electrolysis treatment was performed.
Note that the coating is formed only while the steel plate is directly facing the anode disposed in the treatment liquid, and the time (= energization time) is determined by the anode electrode length and the plate passing speed. In this embodiment, the energization time was set to 0.5 seconds by adjusting the sheet passing speed.
After the cathodic electrolysis treatment, it was washed with water and dried with warm air at 80 ° C. to form a film on both sides. Thus, the steel plate for containers was produced.

In the film formation step, the F ⁻ concentration in the treatment liquid was monitored using an F ion meter during the cathode electrolytic treatment. In the inventive examples (No. 1, 4, 7 and 10), when the F ⁻ concentration becomes larger than the initial value, titanium hydroxide (Ti (OH) ₄ ) is added and F ^- concentration was adjusted to a value of initial stage. This was repeated until the final stage.
The “initial stage” means one minute after the start of the cathodic electrolysis in the film forming process, and the “final stage” means the end point of the cathodic electrolysis in the film forming process (hereinafter referred to as “the initial stage”). The same).

Titanium hydroxide was prepared each time it was added. In addition, in order to avoid the change to metatitanic acid, it added to the processing liquid within 3 minutes after preparation.
For the preparation of titanium hydroxide, a commercially available 30 mass% titanium sulfate aqueous solution and a 2 mol / L potassium hydroxide aqueous solution were used. After neutralization reaction between titanium sulfate and potassium hydroxide, the pH was adjusted to 4.0 to obtain an aqueous solution in which titanium hydroxide was dispersed.

In some comparative examples (No. 2, 5, 8, and 11), a commercially available metatitanic acid (TiO (OH) ₂ ) was added instead of titanium hydroxide (Ti (OH) ₄ ). The timing and amount of addition of metatitanic acid were the same as in the example in which titanium hydroxide was added. Specifically, no. 2 is No.2. As in No. 1, no. 5 is No.5. As in No. 4, No. 8 is No.8. As in No. 7, 11 is No. 11; Same as 10.

  In another comparative example (No. 3, 6, 9 and 12), neither titanium hydroxide nor metatitanic acid was added. In this case, “None” is described in the “Additives” column of Table 1 below.

In each example, the Ti concentration (hexafluorotitanate ion (TiF ₆ ²⁻ ) concentration) of the treatment liquid, and the Ti adhesion amount and Ni adhesion amount of the film were determined. Ti concentration was measured using atomic absorption spectrophotometry. Ti adhesion amount and Ni adhesion amount were measured or calculated by the method described above.
In each example, the Ni adhesion amount of the film was in the range of 0.1 to 2.0 mg / m ^{2 in} the “initial stage” and the “final stage”.
The Ti concentration of the treatment liquid and the Ti adhesion amount of the film are shown in Table 1 below.

<Other notes>
Regarding the “treatment solution composition” in Table 1 below, the content of potassium hexafluorotitanate (molecular weight: 240.08) “10 g / L” is converted to hexafluorotitanate ion (TiF ₆ ²⁻ ). The amount obtained is “0.042 mol / L”.
Similarly, the content “2 g / L” of nickel sulfate hexahydrate (molecular weight: 262.85) is “0.0076 mol / L” in terms of Ni ion (Ni ²⁺ ).
Similarly, the content “50 g / L” of potassium sulfate (molecular weight: 174.26) is 0.29 mol / L. Therefore, the molar ratio with respect to Ti is “6.9”.

As is apparent from the results shown in Table 1 above, in the inventive examples (Nos. 1, 4, 7 and 10) to which titanium hydroxide was added, the increase in F ⁻ concentration in the treatment liquid was suppressed, and the Ti adhesion of the film The decrease in the amount could be suppressed.
On the other hand, in the comparative examples (Nos. 2, 5, 8 and 11) to which metatitanic acid was added, the effect of suppressing the increase in the F ⁻ concentration in the treatment liquid was insufficient, and the Ti adhesion amount of the film was reduced.
Moreover, the comparative example (No. 3, 6, 9, and 12) which did not add titanium hydroxide and metatitanic acid also had the Ti adhesion amount of the film | membrane reduced.

  In the example in which potassium sulfate was added as a salt (conducting aid) to the treatment liquid, a film could be formed by electrolytic treatment at a higher current density than in the example in which potassium sulfate was not added.

Claims (4)

Plated steel sheet covering at least a part of the surface of the steel sheet with a plating layer including at least one layer selected from the group consisting of a Ni layer, a Sn layer, a Ni—Fe alloy layer, a Fe—Sn—Ni alloy layer, and a Fe—Sn alloy layer On the other hand, a film containing Ti is formed on the surface of the plated steel sheet on the plating layer side by performing cathodic electrolytic treatment in a treatment liquid containing hexafluorotitanic acid and / or a salt thereof. A method for producing a steel plate for containers,
When F ⁻ concentration in the treatment liquid is increased by the cathodic electrolysis treatment , titanium hydroxide is added to the treatment liquid, and when the F ⁻ concentration in the treatment liquid is not increased by the cathodic electrolysis treatment , The manufacturing method of the steel plate for containers which does not add titanium hydroxide in the said process liquid . The content of the hexafluorotitanic acid and / or salt thereof in the treatment liquid is 0.004 to 0.400 mol / L in terms of hexafluorotitanate ion (TiF ₆ ²⁻ ). The manufacturing method of the steel plate for containers of Claim 1. The treatment liquid further contains a Ni component,
The method for producing a steel plate for containers according to claim 1 or 2, wherein the content of the Ni component in the treatment liquid is 0.002 to 0.040 mol / L in terms of Ni ion (Ni ²⁺ ). . It said processing liquid, further, K ^+, and at least one cation selected from the group consisting of Na ⁺ and _{^{NH 4 +, SO 4 2-,}} NO 3 - and Cl ^- at least one selected from the group consisting of Contains a salt consisting of a combination with anions,
The manufacturing method of the steel plate for containers of any one of Claims 1-3 whose content of the said salt in the said process liquid is 0.1-100 in the molar ratio with respect to Ti.