TW201641748A - Method for producing surface-treated steel plate - Google Patents

Abstract

Provided is a method for producing a surface-treated steel plate (1), said method comprising: a phosphate compound layer formation step in which a tin-plated steel sheet (10) obtained by plating a steel plate (11) with tin plating (12) is immersed in an immersion treatment liquid containing phosphate ions without performing electrolytic treatment in order to perform immersion treatment and thereby form a phosphate compound layer (20) on the tin-plated steel plate (10); and an aluminum-oxygen compound layer formation step in which an aluminum-oxygen compound layer (30) is formed on the phosphate compound layer (20) by electrolytic treatment using an electrolytic treatment liquid that contains aluminum.

Description

Method for manufacturing surface treated steel sheet

The present invention relates to a method of producing a surface treated steel sheet.

A method of applying chromate treatment to a surface of a substrate used in a metal container, home electric appliance, building material, vehicle, aircraft, etc., but a chromium-free surface treatment has also been developed to replace the chromate. deal with. For example, Patent Document 1 discloses a chromium-free surface treatment technique in which an aluminum oxide metal oxide film is formed on the surface of a substrate by a cathodic electrolysis treatment using an electrolytic treatment liquid containing aluminum ions.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2006-348360

[Summary of the Invention]

However, the prior art described in the above Patent Document 1 In the case where the surface-treated steel sheet is used in a food-drinking tank or the like, it is reacted with sulfur contained in foods and drinks during storage for a long period of time, and there is a problem that blackening and vulcanization becomes black on the surface.

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface-treated steel sheet which can effectively suppress vulcanization and blackening.

The inventors of the present invention have found that a phosphoric acid compound layer containing tin phosphate is formed by immersion treatment using a immersion treatment liquid containing a phosphate ion on a tin-plated steel sheet, and aluminum having an aluminum oxide compound as a main component is formed on the phosphate compound layer. The above object can be attained by the oxygen compound layer, and the present invention has been completed.

That is, according to the present invention, a method of manufacturing a surface-treated steel sheet having the following steps can be provided:

The tin-plated steel sheet to which tin plating is applied to the steel sheet is immersed in an immersion treatment liquid containing phosphate ions without electrolytic treatment, and a phosphorus content of 0.4 to 10 mg/m is formed on the tin-plated steel sheet. A phosphoric acid compound layer forming step of the phosphoric acid compound layer of ² , and an aluminum oxide compound layer forming step of forming an aluminum oxide compound layer by electrolytic treatment using an electrolytic treatment liquid containing aluminum on the phosphoric acid compound layer.

In the production method of the present invention, in the phosphoric acid compound layer forming step, the immersion treatment liquid is preferably a treatment liquid having a pH of 1.0 to 4.0.

In the production method of the present invention, the phosphoric acid compound layer forming step In the case where the tin-plated steel sheet is immersed, the temperature of the immersion treatment liquid is preferably 35 to 55 °C.

In the production method of the present invention, the total amount of aluminum contained in each layer formed on the tin-plated steel sheet is preferably 3 to 40 mg/m ² .

In the production method of the present invention, in the aluminoxy compound layer forming step, the electrolytic treatment liquid is preferably a treatment liquid having a phosphorus content of 0.55 g/L or less.

In the production method of the present invention, in the aluminoxy compound layer forming step, it is preferred that the electrolytic treatment liquid is a treatment liquid containing substantially no F ions.

In the manufacturing method of the present invention, the tin-plated steel sheet is formed by using the steel sheet, a tin alloy layer formed on the steel sheet, and a tin-plated layer having a tin amount of 0.5 g/m ² or more formed on the tin alloy layer. The tin plated steel is preferred.

According to the present invention, a phosphoric acid compound layer having a phosphorus content of 0.4 to 10 mg/m ² is formed on the tin-plated steel sheet by immersion treatment using an immersion treatment liquid containing a phosphate ion, whereby aluminum oxide is formed on the phosphoric acid compound layer. The compound layer contains a phosphate in the aluminum oxide compound layer. Further, by the action of the phosphate in the aluminum oxide compound layer, a surface-treated steel sheet which prevents blackening of the surface due to sulfur can be provided.

1‧‧‧Surface treated steel plate

10‧‧‧ tinplate

11‧‧‧ steel plate

12‧‧‧ tin plating

20‧‧‧ Phosphate compound layer

30‧‧‧Aluminum oxide layer

40‧‧‧covered layer

Fig. 1 is a cross-sectional view showing the configuration of a surface-treated steel sheet according to an embodiment of the present invention.

Fig. 2 is a conceptual diagram showing a state in which a phosphoric acid compound layer and an aluminum oxide compound layer are formed on a tin-plated steel sheet.

Fig. 3 is a view showing an example of a metal container formed by using a surface-treated steel sheet according to an embodiment of the present invention.

[Formation of the Invention]

Embodiments of the present invention will be described below based on the drawings.

Fig. 1 is a cross-sectional view showing the configuration of a surface-treated steel sheet 1 according to an embodiment of the present invention. In the surface-treated steel sheet 1 of the present embodiment, first, the tin-plated steel sheet 10 in which the tin-plated layer 12 is formed on the steel sheet 11 is immersed in an immersion treatment liquid containing phosphate ions, and tin-plated on the tin-plated steel sheet 10 One of the layers 12 is partially dissolved, and a phosphate compound layer 20 is formed, and then a part of the phosphoric acid compound layer 20 is dissolved on the phosphoric acid compound layer 20 by electrolytic treatment in an electrolytic treatment liquid containing Al ions. And formed by forming the aluminum oxide compound layer 30.

The surface-treated steel sheet 1 of the present embodiment is not particularly limited, and can be used, for example, as a member such as a can container or a can lid. When the surface-treated steel sheet 1 is used as a member such as a can container or a can lid, the surface-treated steel sheet 1 (for use in a non-coating application in which a coating layer is not formed) may be used as it is, or a can-free can or container may be used. The cover is formed, or as shown in FIG. 1, the aluminum oxide compound layer 30 of the surface-treated steel sheet 1 is formed of an organic material. After the coating layer is formed, a can container or a can lid or the like can be formed.

<tinned steel plate 10>

The tin-plated steel sheet 10 which is a base material of the surface-treated steel sheet 1 of the present invention is obtained by applying tin plating to the steel sheet 11 and forming a tin-plated layer 12 on the steel sheet 11.

The steel sheet 11 for tin plating is not particularly limited as long as it is excellent in workability by processing such as drawing workability, drawing and shrinking workability, drawing processing, and bending recovery processing (DTR), and for example, it can be used. A hot-rolled sheet steel based on an aluminum-killed steel continuous mold material or a cold-rolled steel sheet obtained by cold rolling (cold rolling) of such a hot-rolled steel sheet. Or, for the steel sheet 11 for tin plating, a nickel-plated steel sheet having a nickel-plated layer formed on the steel sheet, which is heated to diffuse heat, and a nickel-iron alloy layer is formed between the steel sheet and the nickel-plated layer to improve corrosion resistance. . Further, when the nickel plating layer is formed into a granular shape, the adhesion of the coating layer can be improved by the anchor effect.

The method of applying tin plating to the steel sheet 11 is not particularly limited, and examples thereof include a tin phenolsulfonate bath, a halogen bath, and a sulfuric acid bath using a known plating bath. The method of applying nickel plating is also not particularly limited, and a well-known Watts bath made of nickel sulfate and nickel chloride can be used, but the nickel plating layer is formed into a granular form, and nickel sulfate is used. The composition of the bath formed with ammonium sulfate is preferred. Further, in the present embodiment, the tin-plated steel sheet 10 obtained by the tin plating may be subjected to a rapid cooling treatment (reflow treatment) by heating to a melting temperature of tin or the like, and may be applied to the steel sheet 11 versus A tin-iron alloy layer is formed between the tin plating layers 12. In the present embodiment, by applying this reflow treatment, the obtained tin-plated steel sheet 10 is formed on the steel sheet 11, and a tin-iron alloy layer and a tin-plated layer 12 are sequentially formed to improve corrosion resistance. Further, in the case where the base layer has a nickel plating layer, an alloy of tin-nickel and tin-nickel-iron may be formed between the steel sheet 11 and the tin-plated layer 12 by the reflow treatment.

In the present embodiment, the tin-plated steel sheet 10 thus obtained is usually oxidized by oxygen on the surface, and an oxide film layer made of SnO _x (x = 1 to 3) is formed on the surface. This SnO _x formed by a layer of oxide, if too much amount of film formed on the adhesion of the phosphate compound layer of tin-plated steel sheet 1020 tends to decrease, and the amount of the film is too small, there tinplate 10 Since it tends to be vulcanized and blackened, it is preferable to adjust it to a moderate amount of film. Therefore, in the present embodiment, the tin-plated steel sheet 10 may be subjected to a treatment for adjusting the film amount of the oxide film layer by removing part or all of the oxide film layer on the surface. For example, the tin-plated steel sheet 10 may be subjected to cathodic electrolysis treatment and anode by using a carbonate aqueous alkali solution such as sodium carbonate or sodium hydrogencarbonate at a current density of 0.5 to 20 A/dm ² and an energization time of 0.1 to 1.0 second. At least one of the electrolytic treatments is performed to remove the oxide film layer on the surface of the tin-plated steel sheet 10. Moreover, the treatment of removing the oxide film layer on the surface of the tin-plated steel sheet 10 may be performed by immersing the tin-plated steel sheet 10 in an acidic aqueous solution such as hydrochloric acid. At this time, the time for immersing the tin-plated steel sheet 10 in the acidic aqueous solution is preferably 2 seconds or less. When the time during which the tin-plated steel sheet 10 is immersed in the acidic aqueous solution is set to the above range, the oxide film layer made of SnO _x can be efficiently removed while suppressing the dissolution of the tin metal portion of the tin-plated layer 12.

The thickness of the tin-plated layer 12 formed on the steel sheet 11 is not particularly limited, and may be appropriately selected depending on the intended use of the surface-treated steel sheet 1 to be produced, but the amount of tin is preferably 0.5 g/m ² or more, more preferably 0.5. ~15g/m ² . In the case where the nickel plating layer is provided, the thickness of the nickel plating layer is not particularly limited, and the thickness of the nickel plating layer is represented by the amount of nickel, preferably 0.01 to 15 g/m ² . In the case where nickel plating is granular, the average particle diameter of the granular nickel is preferably 0.01 to 0.7 μm.

The total thickness of the tin-plated steel sheet 10 is not particularly limited, and may be appropriately selected in accordance with the use of the surface-treated steel sheet 1 to be produced, and is preferably 0.07 to 0.4 mm.

<phosphoric acid compound layer 20>

The phosphoric acid compound layer 20 is a layer containing tin phosphate, and is formed by immersing the above-described tin-plated steel sheet 10 in an immersion treatment liquid containing an aqueous solution of phosphate ions (hereinafter referred to as "immersion treatment"). In the present embodiment, when the tin-plated steel sheet 10 is immersed in the immersion treatment liquid, the electrolytic treatment is not performed (the tin-plated steel sheet 10 and the counter electrode are prepared, and the treatment is performed in the immersion treatment liquid).

In this embodiment, on the tinned steel sheet by 10, the above-described immersion treatment in the left as shown in Figure 2, was dissolved tin from the tin-plated steel sheet 10, to produce bivalent tin ions (Sn ^2+).

Moreover, FIG. 2 is a conceptual view showing a state in which the phosphoric acid compound layer 20 and the aluminum oxide compound layer 30 are formed on the tin-plated steel sheet 10. The left diagram in Fig. 2 shows an example of a reaction in which the tin-plated steel sheet 10 is immersed in an immersion treatment liquid containing phosphate ions. In addition, the center diagram in FIG. 2 shows a state in which a tin oxide for Sn ₃ (PO ₄ ) ₂ or the like which is formed as the phosphoric acid compound layer 20 is subjected to cathodic electrolysis treatment for forming the aluminum oxide compound layer 30. The right diagram in Fig. 2 shows that a tin phosphate compound as a phosphoric acid compound layer 20 and AlPO ₄ and AlPO ₄ and Al ₂ O ₃ as an aluminum oxide compound layer 30 are formed on the tin-plated steel sheet 10. A diagram of the appearance of nH ₂ O and Al(OH) ₃ . Further, in the present embodiment, AlPO ₄ also includes any one of the phosphoric acid compound layer 20 and the aluminum oxide compound layer 30.

In this embodiment, as shown in FIG. 2, from the reaction of tin ions Sn ²⁺ ions and phosphoric acid-based liquid immersion treatment of the plated steel sheet 10 and the like is generated to Sn ₃ (PO _{4) 2,} etc. deposited tin phosphate in the plating Tin steel plate 10 on. Further, tin ions Sn ²⁺ generated from the tin-plated steel sheet 10 are also deposited on the tin-plated steel sheet 10 with tin oxide (SnO _x ).

Further, in the immersion treatment liquid containing phosphoric acid, phosphoric acid (H ₃ PO ₄ ), dihydrogen phosphate ion (H ₂ PO ₄ ^- ), hydrogen phosphate ion (HPO ₄ ^2- ), and phosphate ion are present depending on the pH of the aqueous solution. PO ₄ ^3- ), phosphorous acid (H ₂ PHO ₃ ), phosphite ion (HPHO ₃ ^- , PHO ₃ ^2- ), and the like. In the present embodiment, the tin-plated steel sheet 10 is immersed in the immersion treatment liquid, and as shown in the left diagram of Fig. 2, tin oxide is formed on the surface of the tin-plated layer 12 in the vicinity of the surface of the tin-plated layer 12. It is reduced to produce tin ions Sn ²⁺ and simultaneously forms hydroxide ions (OH ^- ), so the pH rises. In addition, in response to this pH increase, phosphoric acid (H ₃ PO ₄ ), dihydrogen phosphate (H ₂ PO ₄ ^- ), phosphorous acid (H ₂ PHO ₃ ), and phosphorous acid ions (HPHO ₃ ) are mainly present in the immersion treatment solution. ^-, PHO ₃ ^2-). At this time, the tin ions Sn ²⁺ in the immersion treatment liquid are separated from the above-mentioned dihydrogen phosphate (H ₂ PO ₄ ^- ) and phosphite ions (HPHO ₃ ^- , PHO ₃ ^2- ) and the like, and are deposited on the tin-plated steel sheet 10 . On top, a phosphoric acid compound layer 20 is formed.

In the present embodiment, the phosphoric acid compound layer 20 containing tin phosphate is formed by the above-described immersion treatment, and the obtained surface-treated steel sheet 1 is excellent in sulfur blackening resistance. Further, in the present embodiment, the phosphoric acid compound layer 20 containing tin phosphate is formed by the immersion treatment, and the coating layer 40 made of an organic material is formed on the surface of the surface-treated steel sheet 1, and the coating layer 40 is adhered thereto. Excellent sex. In other words, when the aluminum oxide compound layer 30 is directly formed on the surface-treated steel sheet 1, when the coating layer 40 is formed by baking coating or the like, the tin-plated layer 12 of the surface-treated steel sheet 1 is coated by the heat of baking. When the oxide film layer is grown, the aluminum oxide compound layer 30 and the coating layer 40 may be peeled off by the oxide film layer. On the other hand, when the coating layer 40 is formed, the growth of the oxide film layer of the coated tin-plated layer 12 can be suppressed, and as a result, the coating layer 40 formed on the surface of the surface-treated steel sheet 1 can be improved. Adhesiveness.

Further, in the present embodiment, as described above, the phosphoric acid compound layer 20 is formed by the immersion treatment, whereby the favorable aluminum oxide compound layer 30 can be formed on the phosphoric acid compound layer 20. In other words, the inventors of the present invention obtained the following findings by applying the immersion treatment to the tin-plated steel sheet 10, that is, forming dihydrogen phosphate (H ₂ PO ₄ ^- ) and phosphorous acid ions (HPHO ₃ ^- as described above) ^. And PHO ₃ ^2- ) reacts with tin ions to form tin phosphate, and the chemical bonding state or surface morphology of the tin phosphate becomes readily dissolved in the electrolytic treatment liquid used to form the aluminoxy compound layer 30 described later by electrolytic treatment. . In addition, when the inventors of the present invention have found that the aluminum oxide compound layer 30 is formed by electrolytic treatment, in the electrolytic treatment liquid, the phosphoric acid ions formed by the dissolution of the tin phosphate of the phosphoric acid compound layer 20 are precipitated as the aluminum oxide compound layer 30. For the acid or alkali insoluble phosphate, the corrosion resistance of the formed aluminum oxide compound layer 30 can be improved. Therefore, in the case where the surface of the surface-treated steel sheet 1 obtained is not formed with the coating layer 40 containing the organic material as a main component, it is also sufficient to have corrosion resistance, and it is also suitable as a non-coating application in which the coating layer 40 is not formed. Used in metal containers. Further, as the electrolytic treatment for forming the aluminum oxide compound layer 30, the cathodic electrolysis treatment (the tin-plated steel sheet 10 forming the phosphoric acid compound layer 20 is subjected to electrolytic treatment of the cathode), as shown in Fig. 2, the tin-plated steel sheet at the cathode In the vicinity of the surface of 10, tin oxide or the like is reduced to form tin ions Sn ²⁺ and hydroxide ions (OH ^- ) are generated to raise the pH. Here, in the electrolytic treatment liquid, the higher the pH in the electrolytic treatment liquid, the more the ionization equilibrium tends to increase the existence ratio of the phosphate ion (PO ₄ ^3- ). Further, the phosphate precipitated by the phosphate ion (PO ₄ ^3- ) in the aluminum oxide compound layer 30 is particularly resistant to acid or alkali, and the corrosion resistance of the formed aluminum oxide compound layer 30 is further enhanced.

Further, in the surface-treated steel sheet 1 of the present embodiment, as described above, a part of the tin-plated layer 12 of the tin-plated steel sheet 10 is partially dissolved to form a phosphoric acid compound layer 20, and a part of the phosphoric acid compound layer 20 is partially dissolved to form an aluminum oxide compound layer. 30, the tin plating layer 12, the phosphoric acid compound layer 20, and the aluminum oxide compound layer 30 are mixed in the vicinity of the respective interfaces. For example, in the present embodiment, any of the phosphoric acid compound layer 20 and the aluminum oxide compound layer 30 may contain tin phosphate or aluminum phosphate.

The treatment liquid 20 is impregnated with a phosphate compound layer is formed, the compound of the impregnation treatment with a solution of phosphate ions, the phosphoric acid may be used (H ₃ PO _4), sodium dihydrogen phosphate (NaH ₂ PO _4), disodium hydrogen phosphate (Na ₂ HPO ₄ ), phosphorous acid (H ₃ PO ₃ ), and the like. These phosphoric acids and phosphates may be used singly or in combination of each other. Among them, a mixture of phosphoric acid and sodium dihydrogen phosphate is preferable because the tin phosphate as the phosphoric acid compound layer 20 is favorably precipitated.

The concentration of the phosphate ion in the immersion treatment liquid is not particularly limited, and is represented by the amount of phosphorus, and is preferably 5 to 200 g/L. By setting the concentration of the phosphate ion in the immersion treatment liquid to the above range, the tin phosphate can be favorably deposited on the tin-plated steel sheet 10.

The pH of the immersion treatment liquid is not particularly limited, and is preferably from 1 to 4, and more preferably from 1.3 to 3.7. When the pH is not reached 1, the formed tin phosphate may be dissolved. When the pH exceeds 4, the dissolution of the oxide film layer on the surface of the tin-plated steel sheet 10 tends to be insufficient, and a part of the oxide film layer remains, and the phosphoric acid compound layer 20 is hard to be formed. Therefore, the tin-plated steel sheet 10 may not be formed. The formation of the homogeneous phosphoric acid compound layer 20 is a concern. When the pH exceeds 4, the formed tin phosphate becomes difficult to be dissolved in the electrolytic treatment liquid for forming the aluminum oxide compound layer 30, and the aluminum oxide compound layer 30 cannot be appropriately contained with phosphate, and the above-mentioned aluminum oxide compound may not be obtained. The effect of the corrosion resistance of layer 30 is a concern.

The temperature of the immersion treatment liquid is preferably 35 to 55 ° C, more preferably 40 to 50 ° C. When the temperature is too low, there is a fear that the phosphoric acid compound layer 20 is not easily formed. On the other hand, when the temperature is too high, the formed phosphoric acid compound layer 20 is uneven, and streaks are generated, and there is no problem in quality, but the appearance quality is lowered.

<Aluminum oxy-compound layer 30>

In the present embodiment, the tin-plated steel sheet 10 on which the phosphoric acid compound layer 20 is formed is subjected to electrolytic treatment in an electrolytic treatment liquid containing Al ions, and is then subjected to electrolytic treatment to precipitate an aluminum oxide compound on the phosphoric acid compound layer 20. An aluminum oxide compound layer 30 is formed. The electrolytic treatment may be either an anodic electrolysis treatment or a cathodic electrolysis treatment, but from the viewpoint of satisfactory formation of the aluminoxy compound layer 30, cathodic electrolysis treatment is preferred.

The content of Al ions in the electrolytic treatment liquid for forming the aluminum oxide compound layer 30 can be appropriately selected in accordance with the amount of the aluminum oxide compound layer 30 to be formed, but it is preferably expressed by mass concentration of Al atoms. 10g/l, more preferably 1~5g/l. By setting the content of the Al ions in the electrolytic treatment liquid to the above range, the stability of the electrolytic treatment liquid can be improved, and the precipitation efficiency of the aluminum oxide compound can be improved.

In the present embodiment, nitrate ions may be added to the electrolytic treatment liquid for forming the aluminum oxide compound layer 30. When the nitrate ion is added to the electrolytic treatment liquid, the content of the nitrate ion in the electrolytic treatment liquid is preferably 11,500 to 25,000 ppm by weight. By setting the content of the nitrate ion to the above range, the conductivity of the electrolytic treatment liquid can be adjusted to an appropriate range.

Further, it is preferable that the electrolytic treatment liquid for forming the aluminum oxide compound layer 30 does not contain F ions. When the electrolytic treatment liquid for forming the aluminum oxide compound layer 30 is free from F ions, the aluminum oxide compound layer 30 having a small particle diameter and a small particle size can be formed, and the obtained surface-treated steel sheet 1 can be excellent in sulfurization resistance and blackening resistance. By. When F ions are contained in the electrolytic treatment liquid, SnF ₂ is formed, which is surrounded by the aluminum oxide compound layer 30, and the sulfur blackening resistance and corrosion resistance are lowered.

Further, the electrolytic treatment liquid may contain substantially no F ions, and may contain F ions when it is of a heterogeneous quality. That is, in the case of industrial water, the F atom is slightly contained, and thus the F ion from such an F atom may be mixed in the electrolytic treatment liquid. In this case, the F ions in the electrolytic treatment liquid have, for example, F ions or free F ions which form a wrong ion with the metal, and the total amount of these F ions is preferably 50 ppm by weight or less, more preferably 20 ppm or less. When the amount of F ions contained in the electrolytic treatment liquid is more than 5 ppm, it is judged that the electrolytic treatment liquid contains substantially no F ions.

In the present invention, a method of measuring the content of F ions and nitrate ions in the electrolytic treatment liquid may, for example, be a method of performing quantitative measurement by an ion chromatograph.

Further, in the electrolytic treatment liquid for forming the aluminum oxide compound layer 30, an organic acid (such as citric acid, lactic acid, tartaric acid or glycolic acid) or polyacrylic acid, polyiconic acid or phenol resin may be added, at least One or more kinds of additives. In the present embodiment, by adding these additives in an electrolytic treatment solution, either alone or in combination, the formed aluminum oxide compound layer 30 can contain an organic material, whereby the aluminum oxide compound layer can be formed. The adhesion of the coating layer 40 on the 30th.

Moreover, it is preferable to adjust the content of the phosphate ion in the electrolytic treatment liquid for forming the aluminum oxide compound layer 30, and the content of the phosphate ion in the electrolytic treatment liquid is preferably 0.55 g/L or less, more preferably 0.55 g/L or less. It is 0.33 g/L or less, and more preferably 0.11 g/L.

In the present embodiment, when the aluminum oxide compound layer 30 is formed by electrolytic treatment, in the electrolytic treatment liquid for forming the aluminum oxide compound layer 30, tin phosphate or the like is dissolved from the phosphoric acid compound layer 20 to generate phosphate ions. Further, when the amount of the phosphate ions generated is too large, the phosphoric acid ions are bonded to the Al ions, and the aluminum phosphate is precipitated in the electrolytic treatment liquid, whereby the amount of Al ions for forming the aluminum oxide compound layer 30 in the electrolytic treatment liquid is reduced. The formation efficiency of the aluminum oxide compound layer 30 is lowered. Further, in the electrolytic treatment liquid, the aluminum oxy-compound layer 30 formed by the precipitation of aluminum phosphate becomes uneven, and streaks are generated, and there is no problem in quality, but the appearance quality tends to be lowered.

On the other hand, when the content of the phosphate ion in the electrolytic treatment liquid for forming the aluminum oxide compound layer 30 is within the above range, the aluminum oxy-compound layer 30 formed is uniform, and the appearance quality of the obtained surface-treated steel sheet 1 is improved.

When the aluminum oxide compound layer 30 is formed by electrolytic treatment, it is preferable to use a discontinuous electrolysis method in which the cycle of repeated energization and energization is stopped. In this case, the total energization time of the substrate (the total number of cycles of energization and energization stop cycles is repeated) The energization time) is preferably 1.5 seconds or less, more preferably 1 second or less. The number of cycles of energization and energization stop is preferably 1 to 10 times, and it is sufficient to adjust the aluminum content in the aluminum oxide compound layer 30 together with the energization time. Suitable aluminum content of the aluminum oxide layer 30 of the compound, preferably 3 ~ 40mg / m ^2, more preferably 5 ~ 20mg / m ^2, and more preferably 5 ~ 15mg / m ^2, particularly preferably 5.7 to 10.0 mg / m ^2.

Further, when the aluminum oxy-compound layer 30 is formed, the counter electrode provided on the substrate is not dissolved in the electrolytic treatment as long as it is subjected to electrolytic treatment. Any liquid may be used, but the oxygen overvoltage is small and is not easily dissolved in the electrolytic treatment liquid, and is preferably a titanium plate coated with ruthenium oxide or a titanium plate coated with platinum.

The aluminoxy compound layer 30 formed as described above is mainly composed of alumina or the like, but also contains aluminum hydroxide or phosphate. Also, include phosphates such as aluminum phosphate or a compound containing phosphoric oxide _{(Al (PO 4) y O} z , etc.), as this phosphate precipitate the aluminoxane compound layer 30. In other words, in the present embodiment, as described above, when the tin-plated steel sheet 10 on which the phosphoric acid compound layer 20 is formed is subjected to electrolytic treatment by an electrolytic treatment liquid containing Al ions, a part of the tin phosphate of the phosphate compound layer 20 is formed. Dissolved, by the phosphate ions thus produced, and phosphates such as aluminum phosphate or an oxygen compound containing phosphoric acid are precipitated. Further, when the aluminum oxide compound layer 30 is formed, the dissolution of the phosphoric acid compound layer 20 or the partial exposure of the tin plating without the phosphoric acid compound coating causes the tin ion Sn ^{2+ to} be generated in the electrolytic treatment liquid, so that one part other than the tin phosphate A portion of tin oxide (SnO _x ) is contained in the aluminum oxide compound layer 30. According to the present embodiment, when the coating layer 40 is formed by baking coating on the aluminum oxide compound layer 30 by containing phosphate in the aluminum oxide compound layer 30, plating due to heat during baking can be suppressed. The growth of the oxide film layer of the tin steel sheet 10 improves the adhesion of the coating layer 40 formed on the surface of the surface-treated steel sheet 1.

Although the reason why the effect is obtained by including the phosphate in the aluminoxy compound layer 30 is not clear, it is considered as follows. First, as described above, the phosphoric acid compound layer 20 obtained by the immersion treatment contains a chemical bonding state or a surface morphology of tin phosphate, and is easily dissolved in the electrolytic treatment liquid used for forming the aluminum oxide compound layer 30. In addition, by electrolysis When the aluminum oxide compound layer 30 is formed, in the electrolytic treatment liquid, phosphate ions or phosphorous acid ions generated by dissolving tin phosphate in the phosphoric acid compound layer 20 precipitate phosphate in the form of the aluminum oxide compound layer 30, whereby the phosphoric acid is precipitated. The action of the salt suppresses the growth of the oxide film layer of the tin-plated steel sheet 10 due to the heat of baking, and as a result, the adhesion of the coating layer 40 formed on the surface of the surface-treated steel sheet 1 can be improved. Further, in the case where only tin phosphate is formed on the tin-plated steel sheet 10, the tin phosphate film is deteriorated over time, and the coating can be suppressed at the initial stage. The increase in the oxide film in the baking step is gradually weakened, and the adhesion to the coating layer 40 is lowered. In the present invention, by providing the aluminum oxy-compound layer 30, the deterioration of the tin phosphate is suppressed, and the adhesion to the coating layer 40 is good.

The content of aluminum in the aluminum oxide compound layer 30 is preferably 3 to 20 mg/m ² , more preferably 5 to 20 mg/m ² , still more preferably 5 to 15 mg/m ² , and particularly preferably 5.7 to 10.0 mg/ m ² . When the content of aluminum in the aluminum oxide compound layer 30 is too small, when the coating layer 40 made of an organic material is formed by baking coating, the oxide film layer on the surface of the tin-plated steel sheet 10 is increased, whereby the aluminum oxide compound layer 30 and the coating layer 40 tend to be easily peeled off from the oxide film layer. Further, when the content of aluminum in the aluminum oxide compound layer 30 is too large, the aluminum oxide compound layer 30 becomes brittle and there is a fear of cohesive failure.

Further, as described above, the aluminum oxide layer 30 contains a phosphate compound, but the amount of phosphorus oxy-compound layer 30 of (mol / m ²⁾ of the aluminum content (mol / m ²⁾ The content ratio (P / Al), more Preferably, it is 0.06 to 0.35, more preferably 0.06 to 0.20. When the content ratio (P/Al) is less than 0.06, when the coating layer 40 made of an organic material is formed by baking coating, the oxide film layer on the surface of the tin-plated steel sheet 10 is grown by heat during baking. As a result, the aluminum oxide compound layer 30 and the coating layer 40 tend to be easily peeled off from the oxide film layer. On the other hand, when the content ratio (P/Al) exceeds 0.35, the aluminum oxy-compound layer 30 formed is uneven, and streaks are formed, and there is no problem in quality, but the appearance quality tends to be lowered.

As described above, the surface-treated steel sheet 1 of the present embodiment can be obtained.

In the surface-treated steel sheet 1 of the present embodiment, the total amount of phosphorus contained in each layer (tin plating layer 12, phosphoric acid compound layer 20, and aluminum oxide compound layer 30) formed on the steel sheet 11 is preferably 0.4 to 10 mg/m. ² , and more preferably 0.4~2.3mg/m ² . When the total amount of phosphorus contained in each layer is too small, when the coating layer 40 made of an organic material is formed by baking coating, the oxide film layer of the tin-plated steel sheet 10 is grown by the heat during baking, whereby aluminum is formed. The oxygen compound layer 30 and the coating layer 40 tend to be easily peeled off from the oxide film layer. When the total amount of phosphorus contained in each layer is too large, the content ratio of tin phosphate in the phosphoric acid compound layer 20 is increased, and the tin phosphate acts as an insulator. Therefore, when the aluminum oxide compound layer 30 is electrolytically treated, the aluminum oxide compound is formed. When the unevenness is precipitated, the formed aluminum oxide compound layer 30 is stained, and there is no problem in quality, but the appearance quality tends to be lowered.

In the present embodiment, a method of measuring the total amount of phosphorus contained in each layer formed on the steel sheet 11 is, for example, a method of quantitatively analyzing the obtained surface-treated steel sheet 1 by a fluorescent X-ray analyzer.

<Metal container>

The surface-treated steel sheet 1 of the present embodiment is not particularly limited, and can be used as a member such as a can container or a can lid. When the surface-treated steel sheet 1 is used as a member such as a can container or a can lid, the surface-treated steel sheet 1 (for uncoated applications in which the coating layer 40 is not formed) may be used as it is, or the uncoated can or can lid may be used. The coating layer 40 made of an organic material is formed on the aluminum oxide compound layer 30 of the surface-treated steel sheet 1, and then formed into a can container or a can lid or the like. The organic material constituting the coating layer 40 is not particularly limited, and may be appropriately selected for use in the surface-treated steel sheet 1 (for example, a can container filled with a specific content), and examples thereof include a thermoplastic resin or a thermosetting resin.

As the thermoplastic resin, an olefin resin film such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, ionic polymer, or polyethylene terephthalate can be used. Or a polyester film such as polybutylene terephthalate, an unstretched film such as a polyvinyl chloride film or a polyvinylidene chloride film, or a film for biaxial stretching, or nylon 6, nylon 6,6, nylon 11 Polyamide film such as nylon 12 or the like. Among them, an unaligned polyethylene terephthalate obtained by copolymerizing isophthalic acid is particularly preferred. Further, the organic material constituting the coating layer 40 may be used alone or in combination with different organic materials.

As the thermosetting resin, an epoxy-phenol resin, a polyester resin or the like can be used.

When the coating layer 40 is coated with a thermoplastic resin, it may be a single-layer resin layer or a resin layer which is multi-layered by simultaneous extrusion or the like. In the case of using a multi-layered polyester resin layer, the base layer, that is, the surface treated steel On the side of the sheet 1 , a polyester resin having a composition excellent in adhesion is selected, and the surface layer can be selected from a polyester resin having a composition which is excellent in non-adsorptive property, that is, an extractable property or a flavor component, which is advantageous.

When the example of the multilayer polyester resin layer is represented by the surface layer/lower layer, for example, polyethylene terephthalate/polyethylene terephthalate. Isophthalate, polyethylene terephthalate / polyethylene. Cyclohexaneylene dimethylene. Polyethylene terephthalate with less terephthalate and isophthalate. Polyethylene terephthalate with a high content of isophthalate/isophthalate. Isophthalate, polyethylene terephthalate. Isophthalate / [polyethylene terephthalate. Isophthalate and polybutylene terephthalate. The adipate blend or the like is of course not limited to the above examples. Surface layer: The thickness ratio of the lower layer is preferably in the range of 5:95 to 95:5.

In the coating layer 40, a resin preparation agent known per se, such as an anti-adhesion agent such as amorphous ceria, an inorganic filler, various antistatic agents, a lubricant, and an antioxidant (for example, can be prepared according to a known prescription. Tocopherol, etc., ultraviolet absorbers, and the like.

The thickness of the coating layer 40 formed on the surface-treated steel sheet 1 obtained by the present invention is coated with a thermoplastic resin, and is usually in the range of 3 to 50 μm, particularly preferably 5 to 40 μm. In the case of a coating film, after baking, The thickness is 1 to 50 μm, and particularly preferably 3 to 30 μm. When the thickness is less than the above range, the corrosion resistance is insufficient, and when the thickness exceeds the above range, problems are likely to occur in terms of workability.

The surface treated steel sheet 1 obtained by the present invention is The formation of the coating layer 40 can be carried out by any means. For example, when the thermoplastic resin is coated, it can be carried out by an extrusion coating method, a mold film thermal bonding method, a biaxial stretching film thermal bonding method, or the like.

The heat of the polyester resin of the surface-treated steel sheet 1 is carried out by the heat of the molten resin layer and the heat of the surface-treated steel sheet 1. The heating temperature of the surface-treated steel sheet 1 is generally from 90 ° C to 290 ° C, particularly from 100 ° C to 230 ° C, and the temperature of the laminating rolls is suitably in the range of from 10 ° C to 150 ° C.

Further, the coating layer 40 formed on the surface-treated steel sheet 1 may be formed by thermally laminating a polyester resin film previously formed by a T-die method or an air-filling film forming method to the surface-treated steel sheet 1. The film may also be an unstretched film obtained by a die-casting method in which the extruded film is subjected to rapid cooling, or a film obtained by heat-fixing the film by stretching the film at a stretching temperature by sequential or simultaneous biaxial stretching. Biaxially stretched film.

In the surface-treated steel sheet 1 of the present invention, for example, the coating layer 40 is formed on the surface to obtain an organic material-coated steel sheet, and this processing can be formed into a can container. The can container is not particularly limited, and there are, for example, a seamless can 5 (two piece can) as shown in Fig. 3(A) or a three-piece can 5a (a fusion can) as shown in Fig. 3(B). Further, the body 51 and the upper cover 52 constituting the seamless can 5, and the body 51a, the upper cover 52a, and the lower cover 53 constituting the three-piece can 5 are used for forming the coating material 40 in the surface-treated steel sheet 1 of the present embodiment. Formed by coated steel. In Figs. 3(A) and 3(B), a cross-sectional view of the seamless can 5 and the three-piece can 5a is performed by turning the coating layer 40 on the inner surface side of the can, and turning 90. By. The cans 5, 5a shown in Fig. 3(A), 3(B) can be covered by The layer 40 becomes the inner side of the can, and is subjected to extension processing and extension. Re-extension processing, extension. Re-extension bending extension processing (stretching), extension. The extension of the extension extends. Ironing or by extension. It is manufactured by a conventionally known means such as a shirring process.

Also, was given by extension. Re-extension bending extension processing (stretch processing), extension. The extension of the extension extends. The highly-processed seamless can 5 such as a shirring process, particularly preferably the coating layer 40 is composed of a thermoplastic resin coating by an extrusion coating method.

In other words, the organic material-coated steel sheet is excellent in processing adhesion, and therefore, even in the case of severe processing, it is possible to provide a seamless can having excellent adhesion and excellent corrosion resistance.

The surface-treated steel sheet 1 of the present invention is obtained by, for example, obtaining an organic material-coated steel sheet by forming a coating layer 40 on the surface, and then processing the can lid. The can lid is not particularly limited, and examples thereof include a can open lid or a stay-on-tab on type easy open can lid or a full open open can lid.

[Examples]

The invention is specifically illustrated by the following examples, but the invention is not limited to the examples.

Moreover, the evaluation method of each characteristic is as follows.

<Analysis of treatment liquid>

For immersion treatment liquid and electrolytic treatment liquid, use ICP luminescence analysis (Imitated by Shimadzu Corporation, ICPE-9000), the ion concentration of the phosphate ion or the concentration of the Al ion was measured using an ion chromatograph (DIONEX, DX-500) to measure the F ion concentration and the nitrate ion concentration. In addition, the pH of the immersion treatment liquid and the electrolytic treatment liquid was measured using a pH meter (manufactured by Horiba, Ltd.). In addition, the conductivity of the immersion treatment liquid and the electrolytic treatment liquid was measured using a conductivity meter (manufactured by Nikko-hansen Co., Ltd., CyberScan CON110).

<Appearance evaluation>

The appearance of the surface-treated steel sheet 1 was evaluated by visual observation and according to the following criteria.

○: The color tone of the surface of the surface-treated steel sheet 1 was uniform.

×: Speckle was formed on the surface of the surface-treated steel sheet 1.

<Measurement of phosphorus and aluminum amount>

With respect to the surface-treated steel sheet 1, the amount of phosphorus and the amount of aluminum contained in each layer formed on the steel sheet 11 were measured in units of mg/m ² using a fluorescent X-ray analyzer (ZSX100e, manufactured by Rigaku Co., Ltd.). Further, the measured value into the resulting mol / m ² of the units, is calculated phosphorus content (mol / m ²⁾ of the aluminum content (mol / m ²⁾ The content ratio (P / Al). Further, the measurement of the amount of phosphorus and the amount of aluminum and the calculation of P/Al were performed for all of the examples and comparative examples described later.

<Painting adhesion evaluation>

The organic material-coated steel sheet formed by forming the coating layer 40 on the surface-treated steel sheet 1 is subjected to distillation treatment at a temperature of 125 ° C for 30 minutes. After (retorting), a checkerboard mesh having a depth of the steel plate 11 was cut at intervals of 5 mm, peeled off with a tape, and the degree of peeling was visually observed, and evaluated according to the following criteria. Moreover, the coating adhesion evaluation was performed for all the examples and comparative examples mentioned later.

3 points: The peeling of the paint was not observed as a result of visual judgment.

2 points: The peeling of the paint was observed at an area ratio of 1/5 or less by visual judgment.

1 point: The peeling of the coating was observed at an area ratio of more than 1/5 by visual judgment.

In addition, when the surface-treated steel sheet 1 is used as a food-and-drinking tank, it is judged that it has sufficient coating-adhesion property.

<Evaluation of growth of oxide film layer>

The surface-treated steel sheet 1 was heat-treated at a temperature of 205 ° C for 30 minutes, and the amount of the tin oxide film layer formed on the surface of the tin-plated steel sheet 10 before and after the heat treatment was measured. Further, the amount of the oxide film layer was evaluated by the amount of electricity required to remove the oxide film layer by electrochemical reduction. The electrolytic solution was electrolyzed using a 1/1000 N hydrogen bromide solution under the conditions of a current density of 25 μA/cm ² . The evaluation of the growth of the oxide film layer is performed by calculating the value of the oxide film layer after the heat treatment divided by the value of the oxide film layer before the heat treatment (the oxide film layer after the heat treatment/the oxide film layer before the heat treatment). The larger the evaluation, the easier the oxide film layer grows by heat treatment. Moreover, the evaluation of the growth of the oxide film layer was performed for all of the examples and comparative examples described later.

○: The oxide film layer after the heat treatment/the oxide film layer before the heat treatment was 1.2 or less.

△: The oxide film layer after the heat treatment/the oxide film layer before the heat treatment exceeds 1.2 and 1.4 or less.

×: The oxide film layer after the heat treatment/the oxide film layer before the heat treatment exceeded 1.4.

<Vulcanization resistance to blackness evaluation (model solution: model solution)>

The organic material-coated steel sheet formed by forming the coating layer 40 on the surface-treated steel sheet 1 was cut into 40 mm square pieces, and the test piece was produced by a 3 mm-wide tape cut section. Then, the prepared test piece was placed in an empty can (manufactured by Toyo Kogyo Co., Ltd., J280TULC), and the following model solution was filled thereinto, and the test piece was immersed, and then screwed using an aluminum cap, and the temperature was 130 ° C. 5 hours of distillation treatment.

Model solution: containing sodium dihydrogen phosphate (NaH ₂ PO ₄ ) 3.0 g / L, disodium hydrogen phosphate (Na ₂ HPO ₄ ) 7.1 g / L, L-cysteine hydrochloride monohydrate 6 g / L Aqueous solution of pH 7.0

Then, the can was opened to visually observe the degree of blackening of the test piece, and evaluated according to the following criteria. Further, the evaluation of the sulfur blackening resistance (model solution) was carried out for all of the examples and comparative examples described later.

3 points: The result of visual judgment was that the degree of blackening was markedly weaker than that of Comparative Example 3.

2 points: As a result of visual judgment, the degree of blackening was equivalent to that of Comparative Example 3.

1 point: The result of visual judgment was that the degree of blackening was more intense than that of Comparative Example 3.

In addition, when the surface-treated steel sheet 1 is used as a food-and-drinking tank, it is judged that it has sufficient resistance to vulcanization and blackening.

"Embodiment 1"

First, a low carbon cold-rolled steel sheet (plate thickness: 0.225 mm) was prepared as the steel sheet 11.

Next, the prepared steel sheet was subjected to cathodic electrolysis treatment at 60 ° C for 10 seconds using an aqueous solution of an alkali degreaser (Formula 618-TK2, manufactured by Quaker Chemical Co., Ltd., Japan) to degrease. Next, the degreased steel sheet was washed with tap water, and then immersed in a pickling treatment agent (5 vol% aqueous solution of sulfuric acid) at room temperature for 5 seconds to carry out pickling. Then, after washing with tap water, a well-known tin phenolsulfonate bath was used to apply tin plating to the steel sheet under the following conditions to form a tin-plated layer 12 having a tin amount of 2.8 g/m ^{2 on} the surface of the steel sheet. Then, the steel sheet on which the tin-plated layer 12 is formed is washed with water, heated by a direct current, and heated to a temperature equal to or higher than the melting point of tin. Then, the tap water is poured and quenched and reflowed to prepare a tin-plated steel sheet 10.

Bath temperature: 40 ° C

Current density: 10A/dm ²

Anode material: 99.999% metal tin commercially available

Total power-on time: 5 seconds (1 second power-on time, 0.5 second stop time) 5 cycles for 1 cycle)

In addition, the obtained tin-plated steel sheet 10 is immersed in the immersion treatment liquid under the following conditions to form the phosphoric acid compound layer 20 on the tin-plated steel sheet 10.

Immersion treatment liquid: an aqueous solution of pH 1.3 in which phosphorous acid is dissolved at a concentration of 10 g/L (treatment liquid A of Table 1)

Temperature of the immersion treatment solution: 40 ° C

Dipping time: 3 seconds

Further, the immersion treatment liquid for forming the phosphoric acid compound layer 20 was analyzed for the treatment liquid according to the above method. The results are shown in Table 1. Table 1 also shows the concentration (g/L) of the phosphorus atom calculated by blending the concentration of the dissolved phosphate compound. For the formation of the phosphoric acid compound layer 20 of Example 1, the immersion treatment liquid represented by the treatment liquid A of Table 1 was used. Similarly, the treatment liquid B was used for the examples 2 and 3 to be described later, and the treatment liquid C was used for the examples 4 and 6 to be described later, and the treatment liquid D was used for the fifth embodiment to be described later. Further, Table 2 shows the conditions of the temperature and the immersion time of the immersion treatment liquid when the phosphoric acid compound layer 20 was formed on the tin-plated steel sheet 10.

Then, the tin-plated steel sheet 10 on which the phosphoric acid compound layer 20 was formed was washed with water, and then immersed in the electrolytic treatment liquid under the following conditions, while stirring the electrolytic treatment liquid, the cerium oxide-coated titanium plate disposed at a position between the poles of 17 mm was placed. As the anode, the aluminum oxide compound layer 30 is formed by applying a cathodic electrolysis treatment. Then, it is washed with water and dried, and a phosphorous compound layer 20 and an aluminum oxide compound are sequentially formed on the tin-plated steel sheet 10. The surface of the layer 30 is treated with a steel sheet 1. Further, the electrolytic treatment liquid for forming the aluminum oxide compound layer 30 was analyzed for the treatment liquid according to the above method. The results are shown in Table 1. In all of the examples and comparative examples described later, the electrolytic treatment liquid represented by the treatment liquid F in Table 1 was used in the formation of the aluminum oxide compound layer 30. Further, the conditions of the electrolytic treatment when the aluminum oxide compound layer 30 was formed are shown in Table 2.

Electrolytic treatment liquid: An aluminum nitrate which is an Al compound is dissolved to form an aqueous solution having an Al ion concentration of 1,500 ppm by weight, a nitrate ion concentration of 15,000 ppm by weight, and a F ion concentration of 0 ppm by weight of pH 3.0 (treatment liquid F of Table 1)

Electrolytic treatment liquid temperature: 40 ° C

Current density: 4A/dm ²

Total power-on time: 0.3 seconds (power-on time 0.3 seconds, number of cycles 1 time)

Further, regarding the obtained indication that the steel sheet 1 was treated, the amount of phosphorus and the amount of aluminum were measured in accordance with the above method. The results are shown in Table 3.

Next, the surface-treated steel sheet 1 was heat-treated at a temperature of 190 ° C for 10 minutes, and then coated with an epoxy phenol-based paint to have a coating film thickness of 70 mg/dm ² after baking and drying, and then baked at a temperature of 200 ° C. After baking for 10 minutes, an organic material-coated steel sheet formed by forming the coating layer 40 on the surface-treated steel sheet 1 was obtained. Next, the obtained organic material-coated steel sheet was subjected to coating adhesion evaluation, sulfur blackening resistance evaluation (model solution), evaluation of growth of the oxide film layer, and appearance evaluation according to the above method. The results are shown in Table 3.

<<Example 2》

When the phosphoric acid compound layer 20 is formed on the tin-plated steel sheet 10, an aqueous solution (pH 1 in Table 1) in which the phosphoric acid is dissolved at a concentration of 30 g/L and sodium dihydrogen phosphate at a concentration of 30 g/L is used. A surface-treated steel sheet 1 and an organic material-coated steel sheet were produced in the same manner as in Example 1, and evaluated in the same manner. The results are shown in Table 3.

Example 3

When the aluminum oxide compound layer 30 was formed on the phosphoric acid compound layer 20, the surface-treated steel sheet 1 and the organic material-coated steel sheet were produced in the same manner as in Example 2 except that the total energization time was 0.5 seconds. The results are shown in Table 3.

Example 4

When the phosphoric acid compound layer 20 is formed on the tin-plated steel sheet 10, the immersion treatment liquid is an aqueous solution (the treatment liquid C in Table 1) having a concentration of 10 g/L of phosphoric acid and a pH of 2.4 g dissolved in a concentration of 30 g/L. The surface-treated steel sheet 1 and the organic material-coated steel sheet were produced in the same manner as in Example 1, and evaluated in the same manner. The results are shown in Table 3.

"Embodiment 5"

When the phosphoric acid compound layer 20 is formed on the tin-plated steel sheet 10, the immersion treatment liquid is an aqueous solution of pH 3.7 in which phosphoric acid is dissolved at a concentration of 10 g/L, sodium dihydrogen phosphate at a concentration of 30 g/L, and trisodium phosphate at a concentration of 7 g/L. (Processing liquid D in Table 1), the surface was prepared in the same manner as in Example 1 except that the immersion time was 4 seconds. The steel sheet 1 and the organic material-coated steel sheet were treated and evaluated in the same manner. The results are shown in Table 3.

"Embodiment 6"

Before the formation of the phosphoric acid compound layer 20 on the tin-plated steel sheet 10, the tin-plated steel sheet 10 is immersed in an aqueous solution containing hydrochloric acid. Then, the immersion time when the phosphoric acid compound layer 20 was formed on the tin-plated steel sheet 10 was 2 seconds, the number of cycles when the aluminum oxide compound layer 30 was formed on the phosphoric acid compound layer 20 was 2, and the total energization time was set to 0.6 seconds. The surface-treated steel sheet 1 and the organic material-coated steel sheet were produced in the same manner as in Example 4, and evaluated in the same manner. The results are shown in Table 3.

Comparative Example 1

When the phosphoric acid compound layer 20 is formed on the tin-plated steel sheet 10, the immersion treatment liquid is impregnated with an aqueous solution (treatment liquid E in Table 1) in which phosphoric acid is dissolved at a concentration of 10 g/L and sodium dihydrogen phosphate at a concentration of 30 g/L (pH 1 in Table 1). The surface-treated steel sheet 1 and the organic-coated steel sheet were produced in the same manner as in Example 1 except that the time was 5 seconds, and the evaluation was carried out in the same manner. The results are shown in Table 3.

Comparative Example 2

When the phosphoric acid compound layer 20 was formed on the tin-plated steel sheet 10, the surface-treated steel sheet 1 and the organic material-coated steel sheet were produced in the same manner as in Example 4 except that the temperature of the immersion treatment liquid was 30 ° C, and the evaluation was carried out in the same manner. The results are shown in Table 3.

Comparative Example 3

The phosphoric acid compound layer 20 was not formed, and the aluminum oxide compound layer 30 and the coating layer 40 were sequentially formed by the same method as in Example 1 on the tin-plated steel sheet 10 to obtain a surface-treated steel sheet and an organic material-coated steel sheet. Further, the obtained surface-treated steel sheet and organic material-coated steel sheet were evaluated in the same manner as in Example 1. The results are shown in Table 3.

"Inspection"

As shown in Table 3, it was confirmed that the phosphorous compound layer 20 having a phosphorus amount of 0.4 to 10 mg/m ^{2 was} formed by applying the immersion treatment to the tin-plated steel sheet 10, and the aluminum oxide compound layer 30 was formed on the phosphoric acid compound layer 20. In Examples 1 to 6, the coating adhesion evaluation, the evaluation of the sulfur blackening resistance (model solution), the growth evaluation of the oxide film layer, and the appearance evaluation were all good, and the appearance quality was excellent, and the adhesion of the coating layer 40 was It is excellent in corrosion resistance and sulfur blackening resistance, and is suitable for use in metal containers for long-term use.

In addition, as shown in Table 3, in Comparative Examples 1 and 2 in which the amount of phosphorus in the phosphoric acid compound layer and the aluminum oxide compound layer was 0.2 mg/m ² or less, the results of coating adhesion evaluation and sulfur blackening resistance were evaluated. The average difference is that the adhesion of the coating layer 40 is poor, and the physical content is poor. Further, in Comparative Example 3 in which the phosphoric acid compound layer 20 was not formed by the immersion treatment and the aluminum oxide compound layer 30 was directly formed on the tin-plated steel sheet 10, the coating adhesion evaluation and the growth evaluation of the oxide film layer were both poor. The coating layer 40 has poor adhesion.

1‧‧‧Surface treated steel plate

10‧‧‧ tinplate

11‧‧‧ steel plate

12‧‧‧ tin plating

20‧‧‧ Phosphate compound layer

30‧‧‧Aluminum oxide layer

40‧‧‧covered layer

Claims (7)

A method for producing a surface-treated steel sheet, comprising the step of immersing in a immersion treatment liquid containing phosphoric acid ions without performing electrolytic treatment on a tin-plated steel sheet obtained by applying tin plating on a steel sheet; a phosphor compound layer forming step of forming a phosphoric acid compound layer having a phosphorus amount of 0.4 to 10 mg/m ² on the tin-plated steel sheet, and forming an aluminum oxide compound by electrolytic treatment using an electrolytic treatment liquid containing aluminum on the phosphoric acid compound layer A layer of aluminum oxide compound layer forming step. The method for producing a surface-treated steel sheet according to the first aspect of the invention, wherein in the phosphoric acid compound layer forming step, the immersion treatment liquid is a treatment liquid having a pH of 1.0 to 4.0. The method for producing a surface-treated steel sheet according to claim 1, wherein in the phosphoric acid compound layer forming step, the temperature of the immersion treatment liquid when the tin-plated steel sheet is immersed is 35 to 55 °C. The method for producing a surface-treated steel sheet according to the first aspect of the invention, wherein the total amount of aluminum contained in each layer formed on the tin-plated steel sheet is 3 to 40 mg/m ² . The method for producing a surface-treated steel sheet according to the first aspect of the invention, wherein in the aluminoxy compound layer forming step, the electrolytic treatment liquid is a treatment liquid having a phosphorus content of 0.55 g/L or less. The method for producing a surface-treated steel sheet according to the first aspect of the invention, wherein in the aluminoxy compound layer forming step, the electrolytic treatment liquid is a treatment liquid containing substantially no F ions. The method for producing a surface-treated steel sheet according to any one of claims 1 to 6, wherein the tin-plated steel sheet is formed by using the steel sheet, a tin alloy layer formed on the steel sheet, and the tin alloy layer. A tin-plated steel sheet made of a tin-plated layer having a tin amount of 0.5 g/m ² or more.