KR20160088361A - Steel sheet for container and manufacturing method therefor - Google Patents

Abstract

A steel sheet for a container excellent in appearance is provided. Wherein said steel sheet for a vessel comprises a coated steel sheet at least partially covering the surface of the steel sheet with a plating layer containing at least one layer selected from the Sn layer, the Fe-Sn-Ni alloy layer and the Fe-Sn alloy layer, Wherein a tin oxide film containing tin oxide is interposed between the plating layer and the coating film and the amount of electricity required for reduction of the tin oxide is 2.0 to 5.0 mC / Wherein the coating contains Ti and the coating amount of the coated steel sheet in terms of Ti per one side is 2.5 to 30.0 mg / m 2.

Description

TECHNICAL FIELD [0001] The present invention relates to a steel sheet for a container,

The present invention relates to a steel sheet for a container and a manufacturing method thereof.

As a steel sheet (steel sheet for containers) to be used in containers such as cans, for example, Patent Document 1 discloses that " With the formed ... As the metal plate, the inorganic surface treatment layer is formed by: Ti or Ti and Zr oxides containing phosphoric acid ions and containing F and hydroxyl groups, Coated metal plate for a can or a lid, wherein the weight-average thickness of the Ti is 5 to 300 mg / m < 2 >.

Japanese Patent No. 4487651

The inventors of the present invention have studied the steel sheet for a container described in Patent Document 1 and found that it is relatively good for adhesion to a coating material (hereinafter simply referred to as " adhesion property ").

Therefore, these steel sheets for containers were further examined. Specifically, a case where a coated steel sheet whose surface is covered with a plating layer containing Sn such as a Sn layer or an Fe-Sn alloy layer is used as a steel sheet (metal sheet) on which a coating film (surface treatment layer) containing Ti is disposed Respectively.

As a result, in the case where the amount of Ti in the coating film is excessively large (for example, when the amount of adhesion of the coated steel sheet in terms of Ti per one surface of the coated steel sheet is 5 mg / m 2 or more), the coating film may exhibit a tea- It is evident that a change in color tone is caused to occur during storage under a dark condition, thereby displaying a darker color of darker color. Such a change in color tone (color of the tea system) deteriorates the appearance of the steel sheet for the container and significantly impairs the value of the product.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object thereof is to provide a steel sheet for containers having excellent appearance.

The present inventors have made intensive investigations in order to achieve the above object. As a result, it has been found that by forming a specific tin oxide film between a plating layer such as an Sn layer and a Ti-containing coating film, it is possible to suppress the coloring of the coating film and the coloring- And completed the present invention.

That is, the present invention provides the following [1] to [7].

[1] A coated steel sheet, comprising a plated steel sheet covered at least a part of the surface of a steel sheet with a plated layer containing at least one layer selected from among an Sn layer, an Fe-Sn-Ni alloy layer and an Fe-Sn alloy layer, Wherein a tin oxide film containing tin oxide is interposed between the plating layer and the coating film, the amount of electricity required for reduction of the tin oxide is 2.0 to 5.0 mC / cm < 2 >, and the coating film contains Ti , And the amount of coating of the coated steel sheet in terms of Ti per one side is 2.5 to 30.0 mg / m 2.

[2] The steel sheet for a container according to the above [1], wherein the coating contains Ni and the adhesion amount of the coated steel sheet in terms of Ni per one side is 0.1 to 20.0 mg / m 2.

[3] In the atomic concentration distribution in the depth direction from the surface of the coating film, a depth L (unit: nm) in which the atomic concentration of zero valence Sn becomes equal to 25% of the atomic concentration of Sn in the plating layer, Described in [1] or [2], wherein the product X of the average atomic concentration A (unit: atomic%) of zero-valued Sn from the surface of the film to the depth L satisfies the following formula (1) Steel plate for use.

0? X (= L x A)? 60 ... (One)

[4] A method for producing a steel sheet for a container according to [1] above, wherein at least a part of the surface of the steel sheet is coated with at least one layer selected from an Sn layer, an Fe-Sn-Ni alloy layer and an Fe- Is formed on the surface of the plated steel sheet on the side of the plated layer by dipping the plated steel sheet covered with the plated layer containing the plated steel sheet with the precoating solution containing the oxidizing agent or carbonate or by performing the anodic electrolytic treatment in the pretreatment liquid A pretreatment step and a film forming step of forming a film on the surface of the tin oxide film by subjecting the plated steel sheet on which the tin oxide film is formed to cathodic electrolytic treatment in a treatment liquid containing a Ti component A method of manufacturing a steel sheet.

[5] A method for producing a steel sheet for a container according to [2] above, wherein at least a part of the surface of the steel sheet is coated with at least one layer selected from an Sn layer, an Fe-Sn-Ni alloy layer and an Fe- Is formed on the surface of the plated steel sheet on the side of the plated layer by dipping the plated steel sheet covered with the plated layer containing the plated steel sheet with the precoating solution containing the oxidizing agent or carbonate or by performing the anodic electrolytic treatment in the pretreatment liquid A pretreatment step and a film forming step for forming a film on the surface of the tin oxide film by subjecting the plated steel sheet on which the tin oxide film is formed to cathodic electrolytic treatment in a treatment liquid containing a Ti component and a Ni component Wherein said method comprises the steps of:

[6] The process according to [4] or [5], wherein the oxidizing agent is at least one member selected from the group consisting of perchlorates, an alkali metal or an alkaline earth metal peroxide, hydrogen peroxide or a derivative thereof, and the carbonate is an alkali metal carbonate. [5] The method for producing a steel sheet for a container according to [5].

[7] The method for producing a steel sheet for a container according to any one of [4] to [6], wherein the amount of Sn per one surface of the steel sheet in the plating layer is 0.1 to 15.0 g / m 2.

According to the present invention, it is possible to provide a steel sheet for a container excellent in appearance.

1 is a graph showing an example of the atom concentration distribution in the depth direction from the surface of the coating.
2 is a graph showing an example of the relationship between X and L values.

[Steel for Container]

The steel sheet for a container of the present invention is characterized by comprising a plated steel sheet having a plated layer (hereinafter referred to as a " tin plated layer ") containing Sn such as a Sn layer or an Fe-Sn alloy layer and a plated steel plate disposed on the surface of the plated steel sheet on the tin plated layer side And further has a specific amount of a tin oxide film between the tin plating layer and the coating film. As a result, coloring of the coating film and coloring of the coating film over time can be suppressed while retaining the characteristics such as good adhesiveness of the coating film, and the appearance of the steel sheet for containers is excellent.

This mechanism (reason) is not clear, but it is assumed as follows. That is, by forming the tin oxide film, the doping (mainly Sn) from the tin plating layer into the film is suppressed. As a result, reduction of the band gap of titanium oxide, which is the main component of the coating film, is suppressed, and the visible light absorption is reduced. As a result, the color of the color of the primary color is improved. Likewise, the coloring concentration over time in the atmosphere is also improved.

In addition, all of the above mechanisms are inferred, and other than the above mechanisms are also within the scope of the present invention.

Hereinafter, specific aspects of the coated steel sheet, the coating film and the tin oxide film will be described in detail. First, aspects of the coated steel sheet will be described in detail.

[Plated steel plate]

The plated steel sheet has a plating layer including at least one layer selected from a Sn layer, an Fe-Sn-Ni alloy layer and an Fe-Sn alloy layer covering at least a part of the surface of the steel sheet and the steel sheet.

As a steel sheet of a material, a steel sheet for general can is used. The plating layer may be a continuous layer or a discontinuous island. The plating layer may be formed on at least one surface of the steel sheet, or may be formed on both surfaces. The formation of the plating layer can be carried out by a known method depending on the contained metal element.

Hereinafter, the preferred embodiments of the steel sheet and the plating layer will be described in detail.

<Steel plate>

The kind of the steel sheet is not particularly limited. Usually, a steel sheet (for example, a low carbon steel sheet, a very low carbon steel sheet) used as a container material can be used. The manufacturing method and material of the steel sheet are not particularly limited either. And is manufactured by a process such as hot rolling, pickling, cold rolling, annealing, temper rolling, and the like from a typical steel making process.

The steel sheet may be prepared by forming a nickel-containing layer (Ni-containing layer) on its surface, if necessary, and forming a tin plating layer on the Ni-containing layer. A tin plating layer containing Sn can be formed by tin plating using a steel sheet having a Ni-containing layer. As a result, the weldability is improved.

The Ni-containing layer may contain nickel. For example, a Ni plating layer (Ni layer), a Ni-Fe alloy layer, and the like.

The method of applying the Ni-containing layer to the steel sheet is not particularly limited. For example, a known method such as electroplating may be used. When a Ni-Fe alloy layer is provided as the Ni-containing layer, the Ni-Fe alloy layer can be formed by diffusing Ni in the steel by applying Ni to the surface of the steel sheet by electroplating or the like and then annealing.

The amount of Ni deposited in the Ni-containing layer is not particularly limited, and is preferably 50 to 2000 mg / m 2 in terms of Ni amount per one side. Within the above range, it is advantageous in terms of cost.

The Ni deposition amount can be measured by surface analysis by fluorescent X-ray. In this case, a calibration curve relating to the amount of Ni adhered is specified in advance by using a Ni-attached sample already known to have a Ni deposition amount, and the Ni deposition amount is specified relatively using the calibration curve. However, when the coating film described later contains Ni, it is difficult to measure only the amount of Ni in the Ni-containing layer by the surface analysis by the fluorescent X-ray. In this case, the Ni deposition amount in the Ni-containing layer can be obtained by subtracting the Ni deposition amount contained in the coating film described later from the Ni deposition amount obtained by fluorescent X-ray.

&Lt; Plating layer (tin plating layer) >

The plated steel sheet has a plating layer (tin plating layer) containing Sn on the surface of the steel sheet. The tin plating layer may be formed on at least one surface of the steel sheet, or may be formed on both surfaces.

The amount of Sn per one surface of the steel sheet in the tin plating layer is preferably from 0.1 to 15.0 g / m 2, more preferably from 0.2 to 15.0 g / m 2, because the appearance of the steel sheet for a container is better and the corrosion resistance is also excellent. And more preferably 1.0 to 15.0 g / m &lt; 2 &gt; from the viewpoint of excellent workability.

The Sn deposition amount can be measured by surface analysis by fluorescent X-ray. In the case of fluorescent X-rays, a sample with Sn already known is used, and a calibration curve relating to the Sn deposition amount is specified in advance, and the Sn deposition amount is specified relatively using the calibration curve.

The tin plating layer is a layer which covers at least part of the surface of the steel sheet, and may be a continuous layer or a discontinuous layer.

As the tin plating layer, a tin plating layer composed of a Sn layer, which is a plating layer of tin alone, obtained by plating tin, and a tin plating layer made of Fe (Sn layer / steel sheet interface) -Sn alloy layer, or a tin-plated layer in which the entire Sn of the Sn layer is alloyed to form an Fe-Sn alloy layer.

As the tin plating layer, a tin plating is performed on a steel sheet having a Ni-containing layer on its surface, and a tin-plated layer is formed on the lowest layer (Sn layer / steel sheet interface) of the Sn layer obtained by heating and tinning tin by, Ni alloy layer, a Fe-Sn alloy layer, or the like, or a tin plating layer in which the entire Sn of the Sn layer is alloyed to form an Fe-Sn-Ni alloy layer and an Fe-Sn alloy layer.

As a method for producing the tin plating layer, a well-known method (for example, an electroplating method or a method of dipping in molten Sn and plating) can be mentioned.

For example, tin phenol sulfonate plating bath, tin methane sulfonate plating bath, or halogen tin 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 heating and melting treatment was performed at a temperature higher than the melting point (231.9 占 폚) of Sn to alloy the entire Sn of the plated layer (Sn layer) of the tin base or the entire Sn layer to form a tin plating layer having the Fe- Can be manufactured. When the heating and melting treatment is omitted, a plating layer (Sn layer) of tin alone can be produced.

When the steel sheet has a Ni-containing layer on the surface thereof, tin plating is performed on the Ni-containing layer to form a plating layer (Sn layer) of tin alone and heat melting treatment is performed to form a lowermost layer (Sn layer / Or the entire Sn of the Sn layer is alloyed to form an Fe-Sn-Ni alloy layer, an Fe-Sn alloy layer, or the like.

[film]

Next, the coating film will be described. The film is schematically formed as a film containing Ti (titanium element) as a component thereof, using a treatment liquid to be described later.

The coating amount is 2.5 to 30.0 mg / m &lt; 2 &gt; in terms of Ti on one side of the coated steel sheet (hereinafter also referred to as &quot; Ti adhesion amount &quot;). When the Ti adhesion amount is within this range, the adhesion is excellent. The amount of Ti adhered is preferably 3.0 to 20.0 mg / m &lt; 2 &gt; because the adhesion is more excellent.

Further, the coating film preferably further contains Ni (nickel element) because it is more excellent in adhesion. In this case, the amount of deposition (hereinafter also referred to as &quot; Ni deposition amount &quot;) in terms of Ni per one side of the coated steel sheet is preferably from 0.1 to 20.0 mg / m 2, more preferably from 0.4 to 15.0 mg / m 2, Is more preferable.

Ti, Ni and the like in the film are contained as various titanium compounds and nickel compounds, respectively, and the kind and the manner of these compounds are not particularly limited.

The Ti adhesion amount and the Ni adhesion amount are measured by surface analysis by fluorescent X-ray.

Fluorescence X-ray analysis is carried out, for example, by the following conditions.

Apparatus: Fluorescence X-ray analyzer System3270 manufactured by Rigaku Corporation

Measuring diameter: 30 mm

Measuring Atmosphere: Vacuum

Spectrum: Ti-Kα, Ni-Kα

· Slit: COARSE

· Spectroscopic determination: TAP

The peak counts of Ti-K? And Ni-K? In the fluorescent X-ray analysis of the film measured by the above conditions are used.

However, in the case where the plated layer contains Ni (including the case where the plated layer contains no Ni and a case where a steel sheet having a Ni-containing layer is simply used), the surface analysis by the fluorescent X- It is difficult to measure only the amount of Ni deposited.

In this case, by using a cross-sectional observation by a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and a glow discharge emission analysis in combination, The amount of Ni contained in the plating layer can be distinguished.

More specifically, the coating and the end face of the plating layer are exposed by a focused ion beam (FIB) process, and the thickness of the coating is calculated from the cross-section observation by SEM or TEM. Next, the relationship between the sputtering depth and the sputtering time by the glow discharge spectroscopy analysis is obtained. Thereafter, the light emission count integration value by the Ni element in the glow discharge emission analysis up to the sputtering time corresponding to the film thickness is obtained. From the integrated value of light emission count by the Ni element, Ni deposition amount can be obtained by using a previously obtained calibration curve.

Here, the calibration curve is prepared by the following method.

First, a plurality of samples having Ni-containing coatings on a Ni-free plating layer and having different Ni deposition amounts were subjected to glow discharge emission analysis, and counting up to the sputtering time until the light emission count by the Ni element was not detected Find the value. Then, the Ni deposition amount of these samples is determined by surface analysis by fluorescent X-ray. In this manner, a calibration curve of the Ni count integrated value and the Ni deposition amount by the glow discharge luminescence analysis is prepared.

The thickness of the coating film is not particularly limited, but is preferably from 10 to 120 nm, more preferably from 20 to 60 nm. The thickness of the coating can be measured from the cross-sectional profile of the coating by exposing it to ion beam (FIB) processing and observing it through a transmission electron microscope (TEM).

In the steel sheet for a container of the present invention, the atomic concentration of Sn in the plating layer is set to a depth L (unit: m &lt; 2 &gt;) at which the atomic concentration of Sn becomes equal to 25% of the atomic concentration of Sn in the atomic concentration distribution in the depth direction from the surface of the coating. And the product X of the average atomic concentration A (unit: atom%) of zero-valued Sn from the surface of the coating film to the depth L satisfies the following formula (1).

0? X (= L x A)? 60 ... (One)

In the present invention, the atomic concentration distribution is measured by repeating X-ray photoelectron spectroscopy (XPS) measurement after argon sputtering from the surface of the coating. The term &quot; surface of the coating film &quot; refers to the surface of the coating film opposite to the side of the coated steel plate.

1 is a graph showing an example of the atom concentration distribution in the depth direction from the surface of the coating film, wherein the abscissa indicates the depth (unit: nm), which is the distance from the surface of the film, .

(Depth from the surface of the coating film) at which the atomic concentration of 0 Sn becomes equal to 25% of the atomic concentration (bulk concentration) of Sn in the plating layer (tin plating layer) (Unit: atomic%) of Sn at 0 to the depth L from the surface of the coating film is denoted by A, the product X (= L x A) It is preferable to satisfy the formula (1).

Here, the reason why the depth L (unit: nm) which is equal to 25% of the bulk concentration is adopted is that the information from the plating layer (tin plating layer) coexists as the surface of the coating is deeply sputtered. On the contrary, This is because information in the depth direction of the film is not well reflected.

X obtained by multiplying the depth L by 0 to the depth L by the average atomic concentration A of Sn is more reliably located on the upper layer side than the plating layer (tin plating layer), and the content of 0-Sn .

The inventors of the present invention fabricated a test material for a steel sheet for a container and found X (= L x A) for the prepared test material, and then measured the L value indicating brightness by using SQ-2000 manufactured by Nihon Furun Kogyo Co., , And plotted on a graph.

2 is a graph showing an example of the relationship between X and L values, in which the horizontal axis indicates X and the vertical axis indicates L value. From the graph of FIG. 2, it can be seen that the X and L values show a good correlation, and as the value of X becomes larger, the L value decreases.

Here, the larger the L value, the lower the coloring of the coating (the better the appearance is). For example, the L value is preferably 70 or more. Therefore, X is preferably 60 or less, more preferably 38 or less.

When X is 0, 0 indicates that Sn is not contained in the coating film. According to the estimation mechanism described above, the coloration of the coating is suppressed and the appearance becomes good. Therefore, the lower limit of X is theoretically zero. Particularly, in the XPS measurement in which argon sputtering is sequentially performed from the surface, the influence of zero Sn and the bulk of the bulk appears during the measurement. Therefore, when X represents 0, there is actually no case, and there is no case where X becomes less than 5. Therefore, X is preferably 5 or more, and more preferably 10 or more.

As described above, the atomic concentration distribution when X is obtained is measured by repeatedly performing XPS measurement after argon sputtering from the surface of the coating.

QuanteraSXM manufactured by ULVAC-PHI Co., Ltd. was used as the XPS apparatus and the analysis conditions were X-ray source monoclonal Al-K ?, voltage of 15 kV, output of 25 W, measurement area of 100 占 퐉, The irradiation with the electron beam and the Ar ion irradiation is performed simultaneously, and the sputtering condition is set to a sputter rate of 1 nm / min (in terms of SiO ₂ sputter rate) by Ar ions.

At the time of XPS measurement, each element spectrum was subjected to charge correction (shift correction) so that the CC-derived peak of the C1s spectrum was 284.8 eV. The atomic concentration was calculated from the area intensity of each element peak in neroscan and the relative sensitivity coefficient .

The atomic concentration of 0 Sn is determined by referring to the PHI handbook and the database of NIST, and a representative value of the detected energy value of the 0-valent Sn-derived peak and the Sn-oxide derived peak in the Sn3d _5/2 spectrum , 484.8 eV and 486.8 eV, respectively, are used.

[Tin oxide film]

The steel sheet for a container of the present invention has a tin oxide film containing tin oxide between the above-described plating layer and the coating film. The amount of electricity required for the reduction of the tin oxide in the tin oxide film (hereinafter referred to as the &quot; reduced electricity amount &quot;) is 2.0 to 5.0 mC / cm 2.

In the steel sheet for a container of the present invention, by having such a tin oxide film, it is possible to inhibit coloring of the film and coloring of the film over time, and thus the appearance is excellent.

On the other hand, if the reduced amount of electricity is less than 2.0 mC / cm 2, the effect of suppressing Sn doping from the tin plating layer into the film becomes insufficient and the appearance is inferior. If the reduction amount exceeds 5.0 mC / cm &lt; 2 &gt;, Sn doping from the tin plating layer into the film can be suppressed, but the appearance is also inferior due to the color of the tin oxide film itself.

The reduction amount of the tin oxide film is preferably from 3.0 to 5.0 mC / cm 2, more preferably from 3.6 to 5.0 mC / cm 2, because the reduction of the tin oxide film can further suppress the coloring of the coating film and the coloring concentration over time, Lt; 2 &gt; is more preferable.

When the reduction amount of the tin oxide film is 5.0 mC / cm &lt; 2 &gt; or less, deterioration of adhesion due to cohesive failure in the tin oxide film is not easily caused, which is preferable.

The amount of electricity required for the reduction of the tin oxide was obtained by subjecting the steel sheet for a vessel of the present invention to cathodic electrolysis at a constant current of 0.05 mA / cm &lt; 2 &gt; in an aqueous solution of 0.001 mol / l of hydrobromic acid in which dissolved oxygen was removed by means of bubbling, And can be obtained from the product of the time and the current for reducing and removing the tin oxide.

When the film contains Ni, the hydrogen generating current coexists in the above-described constant current method, and the reduction current of the tin oxide can not be directly measured. Therefore, the first reduction current curve obtained by sweeping the potential from the immersion potential to a potential of -0.7 V (vs. Ag / AgCl), and then from the immersion potential to -0.7 V (vs Ag / AgCl), the electric current corresponding to the difference of the second reduction current curve that swells the potential.

[Production method of steel sheet for container]

As a method for producing the above-described steel sheet for a container of the present invention, for example, a method comprising a pretreatment step and a film formation step which will be described later (hereinafter referred to as a "production method of the present invention" . Hereinafter, such a manufacturing method of the present invention will be described.

[Pretreatment process]

The production method of the present invention includes a pretreatment step before a film formation step to be described later. The pretreatment step is a step of immersing a plated steel sheet in a pretreatment liquid containing an oxidizing agent or a carbonate or performing an anodic electrolytic treatment in the pretreatment liquid to form the tin oxide film on the surface of the plated steel sheet on the plated layer side to be.

A part of the plating layer containing Sn contained in the plated steel sheet is oxidized by the oxidizing agent or the carbonate in the pretreatment liquid by immersing the plated steel sheet in the pretreatment liquid or by anodic electrolytic treatment in the pretreatment liquid, Tin oxide film is formed.

The oxidizing agent or carbonate contained in the pretreatment liquid is not particularly limited.

As the oxidizing agent, conventionally known oxidizing agents may be used. For example, chlorine dioxide; Perhalogen acids such as perchloric acid and periodic acid; Perchloric acid salts such as sodium perchlorate, potassium perchlorate and ammonium perchlorate; Chlorites such as sodium chlorite and potassium chlorite; Hypochlorites such as sodium hypochlorite and calcium hypochlorite; Bromates such as sodium bromate and potassium bromate; Iodic acid salts such as sodium iodate and potassium iodate; Periodic acid salts such as sodium iodate and potassium periodate; Peroxides of alkali metals or alkaline earth metals such as sodium peroxide, potassium peroxide, magnesium peroxide, calcium peroxide and barium peroxide; Hydrogen peroxide such as hydrogen peroxide, sodium percarbonate or derivatives thereof; And the like.

As the carbonate, conventionally known water-soluble carbonates can be used. For example, carbonates of alkali metals such as sodium carbonate and potassium carbonate.

Of these, as the oxidizing agent, a peroxide of perchlorate, an alkali metal or an alkaline earth metal, hydrogen peroxide or a derivative thereof is preferable, and sodium carbonate is preferable as the carbonate because the tin oxide film can be formed continuously and densely on the steel sheet .

The content of the oxidizing agent or carbonate in the pretreatment liquid is preferably 5 to 30 g / l, more preferably 10 to 20 g / l, because the tin oxide film can be formed continuously and densely on the steel sheet.

In the pretreatment step, the liquid temperature of the pretreatment liquid at the time of the treatment is preferably from 20 to 80 DEG C, more preferably from 40 to 60 DEG C, because the amount of tin oxide to be formed becomes appropriate and the change in color tone of the coating can be further suppressed. Is more preferable.

The immersing time in the pretreatment liquid is preferably 0.1 to 5 seconds, more preferably 0.2 to 2 seconds, for the same reason as the liquid temperature.

Further, after immersion in the pretreatment liquid, washing treatment may be carried out if necessary.

The electrolysis conditions in the pretreatment solution are electrolytic current density of 1.0 to 10.0 A / dm ² , preferably 3.0 to 6.0 A / dm ² , more preferably 3.0 to 6.0 A / dm ² , Do. The electrification time is preferably 0.1 to 5 seconds, more preferably 0.2 to 2 seconds.

After the electrolytic treatment in the pretreatment liquid, the water treatment may be carried out if necessary.

[Film forming process]

The film forming step is a step of forming the above-described film on the surface of the tin oxide film formed in the pre-processing step, and performing the negative electrode electrolytic treatment on the plated steel sheet having the tin oxide film formed thereon in the treatment liquid described later. Hereinafter, the conditions of the treatment liquid and the cathode electrolytic treatment to be used will be described in detail.

The treatment liquid used in the film formation step contains a Ti component (Ti compound) for supplying Ti (titanium element) to the coating film. The Ti component is not particularly limited. For example, titanium alkoxide, titanyl ammonium oxalate, titanium titanyl potassium dihydrate, titanium sulfate, titanium lactate, titanium hydrofluoric acid (H ₂ TiF ₆ ) and / or salt thereof can be given. Examples of the salt of titanium hydrofluoric acid include potassium hexafluoro titanate (K ₂ TiF ₆ ), sodium hexafluorosilicate (Na ₂ TiF ₆ ), ammonium hexafluoro titanate ((NH ₄ ) ₂ TiF ₆ ) .

Of these, titanium hydrofluoric acid and / or a salt thereof are preferable from the viewpoints of stability of the treatment liquid, ease of acquisition, and the like.

When the titanium hydrofluoric acid and / or a salt thereof is used, the amount of the Ti component in the treatment liquid is preferably 3.0 to 15.0 g / l, more preferably 5.0 to 15.0 g / l in terms of hexafluoro titanate ion (TiF ₆ ^2- ) 10.0 g / l is more preferable.

When the coating contains Ni (nickel element), the treatment liquid used in the coating step contains a Ni component (Ni compound) for supplying Ni (nickel element) to the coating. The Ni component is not particularly limited. For example, nickel sulfate (NiSO ₄ ), nickel sulfate hexahydrate, nickel chloride (NiCl ₂ ), and nickel chloride hexahydrate.

The content of the Ni component in the treatment liquid is preferably 0.1 to 3.0 g / l, more preferably 0.3 to 1.0 g / l, in terms of Ni ion (Ni ²⁺ ).

As the solvent in the treatment liquid, water is usually used, but organic solvents may be used in combination.

The pH of the treatment liquid is not particularly limited, but is preferably 2.0 to 5.0. Within this range, the treatment time can be shortened and the stability of the treatment liquid is excellent. For adjusting the pH, known acid components (for example, phosphoric acid, sulfuric acid) and alkali components (for example, sodium hydroxide and ammonia water) can be used.

The treatment liquid may contain a surfactant such as sodium lauryl sulfate or acetylene glycol if necessary. From the viewpoint of stability over time of the adhesion behavior, the treatment liquid may contain a condensed phosphate such as pyrophosphate.

In addition, the treatment liquid of the present invention may contain a conductive auxiliary agent. Thus, the steel sheet for a container of the present invention is excellent in high-speed operation. Examples of the conductive auxiliary agent include sulfates such as potassium sulfate, sodium sulfate, magnesium sulfate, and calcium sulfate; Nitrates such as potassium nitrate, sodium nitrate, magnesium nitrate, and calcium nitrate; Chloride salts such as potassium chloride, sodium chloride, magnesium chloride, and calcium chloride; And the like.

The content of the conductive auxiliary agent in the treatment liquid of the present invention is preferably 0.01 to 1 mol / l, more preferably 0.02 to 0.5 mol / l.

The liquid temperature of the treatment liquid at the time of performing the treatment in the film formation step is preferably 20 to 80 캜. Within this range, the amount of Ti or the like in the formed film becomes appropriate, and the adhesion is excellent.

In the film forming step, the electrolytic current density at the time of performing the negative electrode electrolytic treatment is preferably 1.0 to 20.0 A / dm ² because the amount of Ti or the like in the formed film becomes appropriate and the adhesion is excellent.

At this time, the energization time of the negative electrode electrolytic treatment is preferably 0.1 to 5 seconds, more preferably 0.3 to 2 seconds, for the same reason as the electrolytic current density. The electric-charge density in the cathode electrolytic treatment is a product of the current density and the energization time, and is appropriately set.

Further, from the viewpoint of removing the impurities on the surface of the coating film, it is preferable to perform the water washing treatment of the obtained steel sheet after the negative electrode electrolytic treatment.

The method of the water washing treatment is not particularly limited. For example, in the case of manufacturing in a continuous line, a method of forming a flush tank after the film-forming tank and immersing it in water successively after the film-treatment is mentioned. The temperature of the water used for the water washing treatment is preferably 40 to 90 占 폚.

The water-washing time is preferably more than 0.5 seconds, and is preferably 1.0 to 5.0 seconds because the water-washing effect is more excellent.

It may be dried instead of the water washing treatment or after the water washing treatment. The temperature and method of drying are not particularly limited, and for example, a conventional dryer or an electric furnace drying method can be applied. The temperature for the drying treatment is preferably 100 占 폚 or lower. Within this range, oxidation of the coating can be suppressed, and the stability of the coating composition can be maintained. The lower limit is not particularly limited, but is usually about room temperature.

The steel sheet for a container of the present invention obtained by the production method of the present invention is used for the production of various containers such as DI can, food can, and beverage can.

Example

Hereinafter, the present invention will be described in detail with reference to Examples. However, the present invention is not limited thereto.

&Lt; Production of coated steel sheet >

A coated steel sheet was produced by the following two methods [(K-1) and (K-2)].

(K-1)

A steel sheet (T4 original plate) having a plate thickness of 0.22 mm was subjected to electrolytic degreasing and pickling, and then tin plating of Sn adhesion amount per side shown in Table 3 was performed. Subsequently, a heating and melting treatment was performed at a temperature not lower than the melting point of Sn to form a Fe-Sn alloy layer and an Sn layer thereon to prepare a plated steel sheet. In this manner, a plating layer composed of an Fe-Sn alloy layer / a Sn layer was formed on both surfaces in order from the lower layer side.

(K-2)

After the nickel plated layer formed by the degreasing electrolyte to the steel sheet (T4 original plate) having a thickness of 0.22 ㎜ and A Watt bath was used as the Ni coating weight per one side as shown in the third _{table, 10 vol.% H 2 +} 90 vol.% N 2 atmosphere Ni-Fe alloy layer (Ni-containing layer) (Ni deposition amount is shown in Table 3) was formed on both sides by annealing at 700 占 폚 in a nitrogen atmosphere to diffuse and penetrate the nickel plating.

Subsequently, the steel sheet having the Ni-containing layer in the surface layer was tin-plated with a Sn adhering amount per side shown in Table 3 by using a tin plating bath. Thereafter, heating and melting treatment was performed at a temperature not lower than the melting point of Sn to form a Fe-Sn-Ni alloy layer and a discontinuous Sn layer thereon to produce a coated steel sheet. Thus, a plating layer composed of a Ni-Fe alloy layer / an Fe-Sn-Ni alloy layer / a Sn layer was formed on both sides in this order from the lower layer side.

&Lt; Pretreatment process (formation of tin oxide film) >

After the prepared coated steel sheet was washed with water, the treatment temperature (liquid temperature) shown in Table 2 and the immersion time or the anodic electrolytic conditions were set in the pretreatment liquid (solvent: water) of the composition shown in Table 1 Tin oxide films were formed on both sides. In the case where the tin oxide film is not formed by the pretreatment step, "-" is described in the second table.

<Coating Formation Step>

Subsequently, the plated steel sheet subjected to the pretreatment step was washed with water, and the treatment temperature (liquid temperature) and the electrolytic condition (shown in Table 2) were measured using the treatment liquid (solvent: water) Current density, energization time, electric quantity density). Thereafter, it was washed with water and dried at room temperature using a blower to form a coating on both sides.

Thereafter, the test materials of the prepared steel sheets for containers were evaluated for appearance and adhesion by the following methods. The contents of each component and evaluation results are collectively shown in Table 3.

The amount of reduction of the tin oxide film, the amount of Ti deposited on the film, and the amount of deposited Ni were measured or calculated by the above-described method.

<Appearance>

"Early Hue"

The steel plate for the container immediately after the preparation (within 60 minutes after the production) was evaluated for the color of the color of the tea color of the coating. Specifically, the L value was measured using SQ-2000 manufactured by Nippon Seiro Co., Ltd. and evaluated according to the following criteria. If? Or?, The coloring of the coating film is inhibited, and the appearance can be evaluated to be excellent.

?: L value 75 or more

○: L value 70 or more and less than 75

?: L value 60 or more and less than 70

×: L value less than 60

"My discoloration"

The steel plate for evaluation of color tone as described above was allowed to stand in a constant temperature and humidity bath at 50 DEG C and a relative humidity of 98% for 72 hours and then the L value was measured in the same manner as the initial color tone and evaluated by the following criteria. If? Or?, It is possible to evaluate that the coloring concentration over time is suppressed and the appearance is excellent.

&Amp; cir &amp;: L value deterioration from initial (within 60 minutes after production) is less than 3

?: The L value deterioration from the initial stage (within 60 minutes after production) was 3 or more and less than 7

DELTA: L value deterioration from the initial stage (within 60 minutes after production) was 7 or more and less than 12

X: The L value deterioration from the initial stage (within 60 minutes after production) was 12 or more

&Lt; Adhesion >

The surface of the prepared steel plate for containers (100 mm wide × 150 mm long) was coated with an epoxy phenolic coating material and baked at 210 ° C for 10 minutes to give a coating amount of 50 mg / dm ² . Then, the coating was applied, and the two sheets of steel sheets for a container prepared under the same conditions were laminated so that the nylon adhesive film was sandwiched therebetween so as to face the coated surface. Thereafter, the pressure was 2.94x10 ⁵ Pa, the temperature was 190 ° C, Under the condition of pressing for 1 sec. Thereafter, this was divided into test pieces having a width of 5 mm. Two sheets of steel sheets for containers of the divided test pieces were peeled off with a tensile tester and the tensile strength at the time of peeling was measured. In each test piece, the average value of the two test pieces was evaluated by the following criteria. Practically, when the result is? Or?, It can be evaluated that the adhesion is excellent.

?: 2.0 kgf or more

?: 1.0 kgf or more and less than 2.0 kgf

X: less than 1.0 kgf

As is clear from the results shown in Tables 1 to 3, it was confirmed that the steel sheets for containers of Inventive Examples 1 to 51 were all excellent in appearance.

Among them, in the case of the present invention in which the value of X is 38 or less, the appearance is better in comparison with the case of the present invention in which the value of X is 39 or more and 60 or less.

On the other hand, it was confirmed that the steel sheets for containers of Comparative Examples 1 to 4, in which the reduced amount of tin oxide film was less than 2.0 mC / cm 2 or 5.0 mC / cm 2, were all inferior in appearance.

Further, in the case of the steel sheet for containers of Comparative Examples 2 to 4, in which the reduction amount of the tin oxide film is more than 5.0 mC / cm 2, Sn doping from the tin plating layer to the coating film is suppressed by the tin oxide film But the L value is lowered due to the coloration of the tin oxide film itself, and it can be considered that the appearance is inferior.

Claims (7)

A plating steel sheet at least a part of the surface of the steel sheet is covered with a plating layer containing at least one layer selected from the Sn layer, the Fe-Sn-Ni alloy layer and the Fe-Sn alloy layer; A steel sheet for a container having a coating film,
And a tin oxide film containing tin oxide between the plating layer and the coating film, wherein an electric quantity required for reduction of the tin oxide is 2.0 to 5.0 mC /
Wherein the coating contains Ti and the coated amount of the coated steel sheet in terms of Ti per one side is 2.5 to 30.0 mg / m 2. The method according to claim 1,
Wherein the coating contains Ni and the adhesion amount of the coated steel sheet in terms of Ni per one side is 0.1 to 20.0 mg / m 2. 3. The method according to claim 1 or 2,
A depth L (unit: nm) in which the atomic concentration of Sn is equal to 25% of the atomic concentration of Sn in the plating layer in the atomic concentration distribution in the depth direction from the surface of the coating, (Unit: atom%) of 0 to Sn and a depth L of Sn satisfy the following formula (1).
0? X (= L x A)? 60 ... (One) A method for producing a steel sheet for a container according to claim 1,
At least part of the surface of the steel sheet is covered with a plating layer containing at least one layer selected from the Sn layer, the Fe-Sn-Ni alloy layer and the Fe-Sn alloy layer is immersed in a pretreatment solution containing an oxidizing agent or a carbonate, A pretreatment step of forming the tin oxide film on the surface of the plated steel sheet on the plating layer side by anodic electrolytic treatment in the pretreatment liquid,
And a film forming step of performing a negative electrode electrolytic treatment on the plated steel sheet on which the tin oxide film is formed in a treatment liquid containing a Ti component to form the film on the surface of the tin oxide film. A method for producing a steel sheet for a container according to claim 2,
At least part of the surface of the steel sheet is covered with a plating layer containing at least one layer selected from the Sn layer, the Fe-Sn-Ni alloy layer and the Fe-Sn alloy layer is immersed in a pretreatment solution containing an oxidizing agent or a carbonate, A pretreatment step of forming the tin oxide film on the surface of the plated steel sheet on the plating layer side by anodic electrolytic treatment in the pretreatment liquid,
A step of forming a film on the surface of the tin oxide film by subjecting the plated steel sheet on which the tin oxide film is formed to cathodic electrolytic treatment in a treatment liquid containing a Ti component and a Ni component, Gt; The method according to claim 4 or 5,
Wherein the oxidizing agent is at least one member selected from the group consisting of perchlorates, peroxides of an alkali metal or an alkaline earth metal, hydrogen peroxide or a derivative thereof,
Wherein the carbonate is a carbonate of an alkali metal. 7. The method according to any one of claims 4 to 6,
Wherein the amount of Sn per one side of the steel sheet in the plating layer is 0.1 to 15.0 g / m &lt; 2 &gt;.

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