TW201531572A - Steel sheet for containers and method for manufacturing therefor - Google Patents

Abstract

Provided is a steel sheet for a container, said steel sheet having an excellent appearance. The steel sheet for a container has: a plated steel sheet which is formed by covering at least one part of a surface of a steel sheet with a plating layer that includes at least one layer selected from among an Sn layer, an Fe-Sn-Ni alloy layer, and an Fe-Sn alloy layer; and a coating film which is disposed on the surface at the plating layer side of the plated steel sheet. The steel sheet for a container has a tin oxide film which contains tin oxide and is between the plating layer and the coating film, the amount of electricity required for reduction of the tin oxide is 2.0-5.0 mC/cm2, the coating film contains Ti, and the adhered amount in terms of Ti per one surface of the plated steel sheet is 2.5-30.0 mg/m2.

Description

Steel plate for container and manufacturing method thereof

The present invention relates to a steel sheet for containers and a method for producing the same.

A steel sheet (a steel sheet for a container) used for a container such as a can, for example, discloses a surface-treated metal sheet coated with a resin for a can or a can lid, which is characterized in that a surface treatment of an inorganic component is formed on the surface of the metal sheet. The metal plate of the layer, the inorganic surface treatment layer... is free of phosphate ions and is formed of an oxide containing Ti and a hydroxyl group from Ti or Ti and Zr, and the weight film of Ti is 5~ 300mg/m ² ” ([Request Item 1]).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 4487651

The inventors of the present invention used the container described in Patent Document 1 After the review of the steel plate, it was found that the adhesion to the paint (hereinafter also referred to as "adhesiveness") was good.

Moreover, further review was carried out on the steel sheets for these containers. Specifically, a plated steel sheet coated with a Sn-containing plating layer such as a Sn layer or an Fe—Sn alloy layer is used as a steel sheet (metal plate) in which a film (surface-treated layer) containing Ti is disposed. Review.

As a result, when it is known that the Ti content in the film is too large (for example, when the adhesion amount in terms of Ti per side of the plated steel sheet of the film is 5 mg/m ² or more), the film exhibits a tea color, and further, it is stored under the atmosphere. It will cause a change in color tone and a darker tea color. This change in color tone (coloring of the tea system) deteriorates the appearance of the steel sheet for a container and significantly impairs the commercial value.

The present invention has been made in view of the above problems, and an object thereof is to provide a steel sheet for a container which is excellent in appearance.

As a result of the active review of the above-mentioned objects, the present inventors have found that by providing a specific tin oxide film between a plating layer such as a Sn layer and a film containing Ti, coloring of the film or coloration over time can be suppressed. Thus the present invention has been completed.

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

[1] A steel sheet for a container, comprising: a plated steel sheet covering at least a part of a surface of the steel sheet with a plating layer selected from at least one of a Sn layer, an Fe-Sn-Ni alloy layer, and an Fe-Sn alloy layer; And a steel sheet for a container disposed on a surface of the plated steel sheet on a side of the plating layer, wherein the plating layer and the film have a tin oxide film containing tin oxide, and the tin oxide is reduced. The amount of electricity required is 2.0 to 5.0 mC/cm ² , and the film contains Ti, and the amount of adhesion in terms of Ti on each side of the plated steel sheet is 2.5 to 30.0 mg/m ² .

[2] The steel sheet for containers according to the above [1], wherein the coating film contains Ni, and the Ni conversion conversion amount of each surface of the plated steel sheet is 0.1 to 20.0 mg/m ² .

[3] The steel sheet for containers according to the above [1] or [2] wherein, in the atomic concentration distribution in the depth direction from the surface of the film, the atomic concentration of zero-valent Sn and the atomic concentration of zero-valent Sn of the plating layer The product product of the average atomic concentration A (unit: atomic %) of the zero-valent Sn from the surface of the film to the depth L satisfies the following formula (1), 0≦, at a depth L of 25% (unit: nm). X (= L × A) ≦ 60... (1).

[4] A method for producing a steel sheet for a container, which is obtained by the steel sheet for a container according to the above [1], comprising the steps of: including a Sn layer, an Fe-Sn-Ni alloy layer, and an Fe-Sn alloy layer. The plated steel sheet of at least one of the selected one of the plating layers covering the surface of the steel sheet is immersed in the treatment liquid containing the oxidizing agent or the carbonate, or is subjected to anodic electrolysis treatment in the pretreatment liquid, thereby performing the plating a step of forming the tin oxide film on the surface of the plating layer side of the steel sheet, and performing a cathodic electrolysis treatment on the plated steel sheet on which the tin oxide film has been formed in the treatment liquid containing the Ti component. A film forming step of forming the above film on the surface of the oxide film.

[5] A method for producing a steel sheet for a container, which is obtained by the steel sheet for a container according to the above [2], comprising the steps of: including a Sn layer, an Fe-Sn-Ni alloy layer, and an Fe-Sn alloy layer. The plated steel sheet of at least one of the selected one of the plating layers covering the surface of the steel sheet is immersed in the treatment liquid containing the oxidizing agent or the carbonate, or is subjected to anodic electrolysis treatment in the pretreatment liquid, thereby performing the plating a step of forming the tin oxide film on the surface of the plating layer side of the steel sheet, and performing a cathodic electrolysis treatment on the plated steel sheet on which the tin oxide film has been formed in the treatment liquid containing the Ti component and the Ni component. A film forming step of forming the film on the surface of the tin oxide film.

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

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

According to the present invention, a steel sheet for a container excellent in appearance can be provided.

Fig. 1 is a view showing an example of atomic concentration distribution in the depth direction from the surface of the film.

Fig. 2 is a graph showing an example of the relationship between X and L values.

[container steel plate]

The steel sheet for a container of the present invention has a plated steel sheet containing a Sn-containing plating layer (hereinafter also referred to as a "tin plating layer") such as an Sn layer or an Fe-Sn alloy layer, and a tin plating layer disposed on the plated steel sheet. A film containing Ti on the surface of the side, and further, a tin oxide film having a specific amount between the tin plating layer and the film. Thereby, on the one hand, it is possible to maintain the characteristics such as good adhesion of the film, and on the other hand, it is possible to suppress the coloration of the film or the coloration over time, and the appearance of the steel sheet for a container is excellent.

The mechanism (reason) is not clear, but it is speculated as follows. That is, by forming a tin oxide film, it is suppressed that impurities (mainly Sn) are doped from the tin plating layer into the film. As a result, the band gap of the titanium oxide which suppresses the main component of the film is reduced, and the visible light absorption is lowered. Thereby, the color of the tea color is improved. Similarly, the temporal coloration deepening when placed in the atmosphere is also improved.

Moreover, the above mechanisms are all speculations, and even within the scope of the present invention, the above mechanism.

Hereinafter, specific examples of the plated steel sheet, the film, and the tin oxide film will be described in detail. First, the state of the plated steel sheet will be described in detail.

[plated steel plate]

The plated steel sheet has a steel sheet and a plating layer containing at least one layer selected from the group consisting of a Sn layer, an Fe-Sn-Ni alloy layer, and an Fe-Sn alloy layer on at least a part of the surface of the coated steel sheet.

Steel sheets for raw materials can be used for steel sheets for general cans. The plating layer may be a continuous layer or a discontinuous island shape. Further, the plating layer may be provided on at least one side of the steel sheet, or may be provided on both surfaces. The formation of the plating layer is carried out by a conventional method depending on the metal element contained.

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

<Steel plate>

The type of the steel sheet is not particularly limited, and a steel sheet (for example, a low carbon steel sheet or an extremely low carbon steel sheet) which is generally used as a container material can be used. The method for producing the steel sheet, the material, and the like are not particularly limited, and are subjected to steps such as hot rolling, pickling, cold rolling, blunt, quenching and tempering, and the like after the usual steel sheet manufacturing step.

The steel sheet may be formed by forming a nickel-containing layer (including a Ni layer) on the surface thereof as needed, or a tin plating layer may be formed on the Ni-containing layer. A tin plating layer containing island-shaped Sn can be formed by applying tin plating to a steel sheet having a Ni-containing layer. As a result, the weldability is improved.

As long as the Ni-containing layer contains nickel. For example, a Ni plating layer (Ni layer), a Ni-Fe alloy layer, or the like is exemplified.

The method of imparting the Ni-containing layer to the steel sheet is not particularly limited, and examples thereof include a conventional plating method. Further, when the Ni-Fe alloy layer is provided as the Ni-containing layer, Ni is imparted to the surface of the steel sheet by electroplating, and Ni is blunt by burning Diffused into the steel to form a Ni-Fe alloy layer.

The amount of Ni adhering in the Ni-containing layer is not particularly limited, and is preferably from 50 to 2000 mg/m ^{2 in terms} of Ni per side. If it is within the above range, it is also advantageous on the cost side.

Further, the Ni adhesion amount can be measured by surface analysis of fluorescent X-rays. In this case, a Ni-attached sample having a known Ni adhesion amount can be used, and a correction line relating to the amount of Ni adhesion can be specified in advance, and the relative adhesion amount of Ni can be specified using the correction line. However, when Ni is contained in the film described later, it is difficult to measure only the amount of Ni deposited in the Ni-containing layer by surface analysis using the above-described fluorescent X-ray. In this case, the Ni adhesion amount in the Ni-containing layer can be obtained by subtracting the Ni adhesion amount contained in the film to be described later from the Ni adhesion amount determined by the fluorescent X-ray.

<plating layer (tin plating layer)>

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

The amount of Sn deposited on each side 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, because the appearance of the steel sheet for a container is more excellent and the corrosion resistance is also excellent. /m ² is more preferably 1.0 to 15.0 g/m ² in terms of excellent workability.

Further, the Sn adhesion amount can be measured by surface analysis of fluorescent X-rays. In the case of fluorescent X-rays, a Sn-attached sample having a known amount of Sn adhesion can be used, and a correction line relating to the amount of Sn adhesion can be specified in advance, and used. The correction line specifies the relative amount of Sn adhesion.

The tin plating layer covers at least a portion of the surface of the steel sheet, and may be a continuous layer or a discontinuous island shape.

In addition to the tin plating layer formed of the Sn layer, which is a plating layer of a tin simple substance obtained by plating tin, the tin plating layer may be obtained by heating and melting tin by electric heating or the like after tin plating. A tin plating layer of an Fe-Sn alloy layer is formed in a portion of the lowermost layer (Sn layer/steel plate interface) of the Sn layer, or a total of Sn of the Sn layer is alloyed to form a tin plating layer of the Fe-Sn alloy layer.

Further, the tin plating layer includes tin plating on a steel sheet having a Ni-containing layer on the surface, and heating and melting the tin by electric heating or the like to obtain a portion (Sn layer/steel plate interface) of the Sn layer partially. Forming a tin-plated layer of an Fe-Sn-Ni alloy layer, an Fe-Sn alloy layer, or the like, or all the Sn of the Sn layer is alloyed to form a Fe-Sn-Ni alloy layer, and a tin-plated layer of the Fe-Sn alloy layer .

The method for producing the tin plating layer is exemplified by a known method (for example, a plating method or a method of immersing in molten Sn for plating).

For example, Sn is plated on the surface of the steel sheet by using a tin phenolsulfonate plating bath, a tin methanesulfonate plating bath, or a halogen-based tin plating bath so that the amount of adhesion per surface is a specific amount. Subsequently, it is subjected to heat-melting treatment at a temperature higher than the melting point of Sn (231.9 ° C), and can be produced in the lowermost layer of the plating layer (Sn layer) of the tin simple body or all the Sn of the Sn layer is alloyed to form an Fe-Sn alloy. A layer of tin plating. When the heat-melting treatment is omitted, a plating layer (Sn layer) of a tin simple substance can be produced.

Further, when the steel sheet has a Ni-containing layer on the surface thereof, a plating layer (Sn layer) in which a tin single body is formed by tin plating on the Ni-containing layer, and a heat-melting treatment is performed on the lowermost layer of the Sn layer (Sn) All of the Sn of the layer/steel plate interface or the Sn layer is alloyed to form an Fe-Sn-Ni alloy layer, an Fe-Sn alloy layer, or the like.

[film]

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

The Ti-conducting amount (hereinafter also referred to as "Ti adhesion amount") on each side of the plated steel sheet is 2.5 to 30.0 mg/m ² . When the Ti adhesion amount is within this range, the adhesion is excellent. The Ti adhesion amount is preferably 3.0 to 20.0 mg/m ² for the reason that the adhesion is more excellent.

Moreover, it is preferable that the film contains Ni (nickel element) for the reason that the adhesion is more excellent. In this case, the Ni conversion amount (hereinafter also referred to as "Ni adhesion amount") on each side of the plated steel sheet is preferably from 0.1 to 20.0 mg/m ² , more preferably from 0.4 to 15.0 mg/m ² , and further Good is 0.4~6.0mg/m ² .

Ti, Ni, and the like in the film are contained as various titanium compounds and nickel compounds, and the kind or form of the compounds is not particularly limited.

Further, the Ti adhesion amount and the Ni adhesion amount were measured by surface analysis by fluorescent X-ray.

Fluorescence X-ray analysis was carried out under the following conditions.

. Device: Fluorescent X-ray analyzer System3270 manufactured by RIGAKU

. Measuring diameter: 30mm

. Measuring environment: vacuum

. Spectrum: Ti-Kα, Ni-Kα

. Gap: Coarse (COARSE)

. Spectroscopic crystallization: TAP

The number of peak counts of Ti-Kα and Ni-Kα was analyzed by fluorescent X-ray analysis of the film measured by the above conditions.

However, when the plating layer contains Ni (including the case where the plating layer does not contain Ni, and only the steel sheet having the Ni layer is used, the same applies hereinafter), it is difficult to measure only the film contained by the surface analysis of the above-mentioned fluorescent X-ray. The amount of Ni attached.

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

Specifically, the cross section of the coating film and the plating layer was exposed by Focused Ion Beam (FIB) processing, and the film thickness was calculated from the cross section observed by SEM or TEM. Next, the relationship between the sputtering depth and the sputtering time was determined by glow discharge luminescence analysis. Subsequently, the cumulative value of the luminescence count due to the Ni element by the glow discharge luminescence analysis up to the sputtering time corresponding to the film thickness was determined. Luminescence counting by the Ni element The cumulative value can be obtained by using a calibration line obtained in advance.

Here, the correction line is created by the following method.

First, a glow discharge luminescence analysis is performed on a plurality of samples having different Ni adhesion amounts on a coating layer containing no Ni on the Ni-free plating layer, and the sputtering time until the luminescence count due to the Ni element is not detected is determined. Count the accumulated value. Next, the amount of Ni adhesion of the samples was determined by surface analysis using fluorescent X-rays. According to this, a correction line of the Ni count cumulative value and the Ni adhesion amount by glow discharge luminescence analysis was prepared.

The film thickness is not particularly limited, and is preferably from 10 to 120 nm, more preferably from 20 to 60 nm. The thickness of the film can be measured by focusing ion beam (FIB) processing to expose the cross section of the film, and the profile obtained by observation through a transmission electron microscope (TEM).

Further, in the steel sheet for a container of the present invention, the atomic concentration of the zero-valent Sn is equal to the depth L of 25% of the atomic concentration of the zero-valent Sn of the plating layer by the atomic concentration distribution in the depth direction from the surface of the coating film (unit: Nm), the product X of the average atomic concentration A (unit: atomic %) of the zero-valent Sn from the surface of the film to the depth L satisfies the following formula (1), and the appearance is more excellent.

0≦X(=L×A)≦60...(1)

In the present invention, the atomic concentration distribution is measured from the surface of the film by X-ray photoelectron spectroscopy (XPS) measurement after argon gas sputtering. Further, the surface of the film refers to the surface of the film opposite to the side of the plated steel sheet.

Figure 1 shows the atomic concentration in the depth direction from the surface of the film. In the graph of the degree distribution, the horizontal axis represents the depth (unit: nm) from the surface of the film, and the vertical axis represents the atomic concentration (unit: atomic %).

In the atomic concentration distribution shown in FIG. 1, the atomic concentration of the zero-valent Sn is equal to 25% of the atomic concentration (total concentration) of the zero-valent Sn of the plating layer (tin plating layer) (from the surface of the film) When the distance is set to L (unit: nm), the average atomic concentration (unit: atomic %) of the zero-valent Sn from the surface of the film to the depth L is set to A, and the product of the two products X (= L × A) is better. The above formula (1) is satisfied.

In this paper, the reason for using the depth L (unit: nm) equal to 25% of the overall concentration is that the deeper the sputtering is performed from the surface of the film, the more the material from the plating layer (tin plating layer) is mixed. Ground, the data closest to the surface of the film is easy to reflect the depth direction of the film.

The X obtained by multiplying the depth L by the average atomic concentration A of the zero-valent Sn of the depth L is more surely present on the upper layer side than the plating layer (tin plating layer), and becomes an index indicating the content of the zero-valent Sn present in the film. .

The present inventors produced a test material for a steel sheet for a container, and obtained X (= L × A) for the test material to be produced, and then measured the L value indicating the brightness using SQ-2000 manufactured by Nippon Denshoku Industries Co., Ltd. And draw a chart.

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

Here, it can be evaluated that the larger the L value is, the more the coloring of the film can be suppressed (the appearance is good), and for example, the L value is preferably 70 or more. Therefore, X is preferably 60. Below, it is better to be 38 or less.

Further, when X is 0, it means that the film does not contain zero-valent Sn, and according to the above-described mechanism, the film coloring is suppressed and the appearance is good. Therefore, the lower limit of X is theoretically set to zero. However, in the measurement of XPS which is sequentially propelled from the surface by argon sputtering, the overall zero-valent Sn has an influence on the measurement. Therefore, X does not actually represent 0, and does not set to less than 5. Therefore, X is preferably 5 or more, more preferably 10 or more.

As described above, the atomic concentration distribution at the time of obtaining X was measured by XPS measurement after argon sputtering from the surface of the film.

The XPS apparatus used for the XPS measurement was a Quantera SXM manufactured by ULVAC-PHI Co., Ltd., and the analysis conditions were an X-ray source monochrome Al-Kα, a voltage of 15 kV, an output of 25 W, and a measurement area of 100 μm. The charged neutralization system was set to irradiate the electron beam simultaneously with the Ar ion irradiation, and the sputtering condition was set to a sputtering rate of Ar ions of 1 nm/min (converted by the SiO ₂ sputtering rate).

In the XPS measurement, the charge correction (offset correction) of each element spectrum is performed such that the peak derived from the CC bond of the C1s spectrum is 284.8 eV, and the atomic concentration is the area intensity of each element peak in the nano scan. The relative sensitivity coefficient of the element is calculated.

In addition, the atomic concentration of zero-valent Sn is based on the PHI manual and the NIST database, and the detected slope is used to detect the peak derived from zero-valent Sn and the peak derived from the Sn oxide in the Sn3d _5/2 spectrum. The representative values of the detected energy values were set to 484.8 eV and 486.8 eV, respectively, and the values calculated by peak separation were calculated.

[tin oxide film]

The steel sheet for a container of the present invention has a tin oxide film containing tin oxide between the plating layer and the film. Further, the amount of electricity required for the reduction of the tin oxide of the tin oxide film (hereinafter also referred to as "reduced amount") is 2.0 to 5.0 mC/cm ² .

In the steel sheet for a container of the present invention, the tin oxide film can suppress the coloration of the film or the coloration over time, and the appearance is excellent.

On the other hand, when the amount of reduction is less than 2.0 mC/cm ² , the effect of suppressing the doping of Sn from the tin plating layer into the film is insufficient, and the appearance is poor. Further, when the amount of reduction is more than 5.0 mC/cm ² , Sn can be inhibited from being doped into the film from the tin plating layer, but the tin oxide film itself is colored, and the appearance is still poor.

Tin oxide film reduction amount, based on the colored coating film can be further suppressed when deepening or by coloring, the containers of steel sheet more excellent appearance reasons, preferably 3.0 ~ 5.0mC / cm ^2, more preferably 3.6 ~ 5.0mC / cm ² .

When the amount of reduction of the tin oxide film is 5.0 mC/cm ² or less, it is less likely to cause a decrease in adhesion due to aggregation failure in the tin oxide film, which is preferable.

The amount of electricity required for the reduction of the tin oxide can be used to remove the dissolved oxygen in the 0.001 mol/L aqueous hydrogen bromide solution by means of a nitrogen gas bubble or the like, and the container of the present invention is used at a constant current of 0.05 mA/cm ² . Cathodic electrolysis of steel plates is obtained by multiplying the time and current of the tin oxide by reduction.

Further, when the film contains Ni, a hydrogen generating current coexists in the constant current method, and the reducing current of the tin oxide cannot be directly measured. Therefore, the phase can be The first reduction current curve obtained by scanning the potential from the immersion potential to the potential of -0.7 V (relative to Ag/AgCl), and thereafter the potential from the immersion potential to -0.7 V (relative to Ag/AgCl) potential The amount of electric power of the difference between the second reduction current curves is obtained.

[Method of Manufacturing Steel Sheet for Container]

The method of producing the steel sheet for a container of the present invention is preferably, for example, a method of sequentially providing a pre-processing step and a film forming step, which will be described later (hereinafter, also referred to as "the manufacturing method of the present invention" for convenience). Hereinafter, the production method of the present invention will be described.

[Pre-Processing Steps]

The manufacturing method of the present invention includes a pretreatment step before the step of forming the film to be described later. The pretreatment step is performed by immersing the plated steel sheet in a treatment liquid containing an oxidizing agent or a carbonate or by performing anodic electrolysis treatment on the pretreatment liquid to form the above-mentioned surface on the plating layer side of the plated steel sheet. The step of tin oxide film.

By plating the plated steel sheet in the pretreatment liquid or performing anodic electrolysis treatment in the pretreatment liquid, the plated steel sheet has a portion of the Sn-containing plating layer due to the oxidant or carbonate in the pretreatment liquid. Oxidation forms a tin oxide film containing tin oxide.

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

As the oxidizing agent, a conventionally known oxidizing agent can be used. List as an example For example, chlorine dioxide; perchloric acid such as perchloric acid or periodic acid; perchlorate such as sodium perchlorate, potassium perchlorate or ammonium perchlorate; chlorite such as sodium chlorite or potassium chlorite ; hypochlorites such as sodium hypochlorite and calcium hypochlorite; bromates such as sodium bromate and potassium bromate; iodates such as sodium iodate and potassium iodate; and iodine such as sodium periodate and potassium periodate Acid salt; peroxide of alkali metal or alkaline earth metal such as sodium peroxide, potassium peroxide, magnesium peroxide, calcium peroxide or barium peroxide; hydrogen peroxide or its derivative such as hydrogen peroxide or sodium percarbonate Wait.

Further, as the carbonate, a conventionally known water-soluble carbonate can be used. For example, it is a carbonate of an alkali metal such as sodium carbonate or potassium carbonate.

In the above, the oxidizing agent is preferably a peroxide of a perchlorate, an alkali metal or an alkaline earth metal, hydrogen peroxide or a derivative thereof, based on the reason that the tin oxide film can be formed continuously and densely on the steel sheet. The carbonate is preferably sodium carbonate.

Further, the oxidizing agent or carbonate content in the pretreatment liquid is preferably from 5 to 30 g/L, more preferably from 10 to 20 g/L, based on the reason that the tin oxide film can be continuously and densely formed on the steel sheet.

In the pretreatment step, the liquid temperature of the treatment liquid before the treatment is performed, and the reason why the amount of the tin oxide film formed is an appropriate amount can further suppress the change in the color tone of the film, and is preferably 20 to 80 ° C, more preferably 40 to 60 °C.

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

Further, after immersing in the pretreatment liquid, it may be subjected to a water washing treatment as needed.

Further, the electrolysis conditions in the pretreatment liquid are preferably electrolyzed so that the steel sheet side becomes an anode for the same reason as the liquid temperature, and the electrolysis current density is 1.0 to 10.0 A/dm ² , more preferably 3.0 to 6.0 A/ Dm ² . The energization time is preferably 0.1 to 5 seconds, more preferably 0.2 to 2 seconds.

After the electrolytic treatment in the pretreatment liquid, a water washing treatment may also be applied as needed.

[film formation step]

The film forming step is a step of forming the film on the surface of the tin oxide film formed in the pretreatment step, and is a step of subjecting the plated steel sheet forming the tin oxide film to a cathodic electrolysis treatment in a treatment liquid to be described later. Hereinafter, the conditions of the treatment liquid or cathodic electrolysis treatment to be used and the like 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 above film. The Ti component is not particularly limited. For example, titanium alkoxide, titanyl oxalate, potassium oxytitanate dihydrate, titanium sulfate, titanium lactate, titanium hydrofluoride (H ₂ TiF ₆ ), and/or a salt thereof are exemplified. Further, the salt of titanium hydrofluoride is exemplified by, for example, potassium hexafluorophosphate (K ₂ TiF ₆ ), sodium hexafluorophosphate (Na ₂ TiF ₆ ), ammonium hexafluorophosphate ((NH ₄ ) ₂ TiF). ₆ ) Wait.

Among these, titanium hydrofluoride and/or a salt thereof is preferred from the viewpoints of stability of the treatment liquid, ease of availability, and the like.

The content of the Ti component in the treatment liquid is preferably 3.0 to 15.0 g/L, more preferably 3.0 to 15.0 g/L, in the case of using titanium hydrofluoride and/or a salt thereof, in terms of titanium fluoride ion (TiF ₆ ^2- ). It is 5.0~10.0g/L.

Further, when the film contains Ni (nickel element), the treatment liquid used in the film formation step contains a Ni component (Ni compound) for supplying Ni (nickel element) to the film. The Ni component is not particularly limited. For example, nickel sulfate (NiSO ₄ ), nickel sulfate hexahydrate, nickel chloride (NiCl ₂ ), nickel chloride hexahydrate or the like is exemplified.

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⁺ ).

Further, water is usually used as the solvent in the treatment liquid, but an organic solvent may be used in combination.

The pH of the treatment liquid is not particularly limited, and is preferably pH 2.0 to 5.0. If it is in this range, the processing time can be shortened, and the stability of the treatment liquid is excellent. The pH can be adjusted using conventional acid components (eg, phosphoric acid, sulfuric acid). An alkali component (for example, sodium hydroxide, ammonia water).

Further, a surfactant such as sodium lauryl sulfate or acetylene glycol may be optionally used in the treatment liquid. Further, the treatment liquid may contain a condensed phosphate such as pyrophosphate based on the stability of the adhesion behavior over time.

Further, the treatment liquid of the present invention may further contain a conduction aid. Therefore, the steel sheet for containers of the present invention is excellent in high-speed workability. The conductive aids are exemplified by sulfates such as potassium sulfate, sodium sulfate, magnesium sulfate, and calcium sulfate; nitrates such as potassium nitrate, sodium nitrate, magnesium nitrate, and calcium nitrate; potassium chloride, sodium chloride, magnesium chloride, calcium chloride, and the like. Chloride salts, etc.

The content of the conduction aid in the treatment liquid of the present invention is preferably from 0.01 to 1 mol/L, more preferably from 0.02 to 0.5 mol/L.

The liquid temperature of the treatment liquid when the treatment is carried out in the film formation step It is preferably 20 to 80 ° C. When it is this range, Ti etc. in the film formed will become an appropriate amount, and it is excellent in adhesiveness.

In the film formation step, the electrolysis current density at the time of performing the cathodic electrolysis treatment is preferably 1.0 to 20.0 A/dm ² for the reason that the Ti or the like in the formed film is an appropriate amount and the adhesion is excellent.

At this time, the energization time of the cathodic electrolysis treatment is preferably from 0.1 to 5 seconds, more preferably from 0.3 to 2 seconds, for the same reason as the electrolysis current density. Further, the electric quantity density at the time of the cathodic electrolysis treatment is the product of the current density and the energization time, and is appropriately set.

Further, from the viewpoint of removing impurities on the surface of the film, after the cathodic electrolysis treatment, the water-washing treatment of the obtained steel sheet is preferably carried out.

The method of the water washing treatment is not particularly limited. For example, when it is produced by a continuous production line, it is exemplified as a method in which a water washing tank is provided after the coating treatment tank, and the film is continuously immersed in water after the treatment. The temperature of the water used for the water washing treatment is preferably from 40 to 90 °C.

The washing time is preferably more than 0.5 second, and preferably 1.0 to 5.0 seconds, based on the reason that the effect by the water washing treatment is more excellent.

It may be replaced by a water washing treatment or dried after a water washing treatment. The temperature and the manner of drying are not particularly limited, and for example, a usual dryer or an electric furnace drying method can be used. The temperature at the time of drying treatment is preferably 100 ° C or less. When it is in the above range, oxidation of the film can be suppressed, and the stability of the film composition can be maintained. Further, the lower limit is not particularly limited, but is usually about room temperature.

The container of the present invention obtained by the production method of the present invention The steel plate is used in the manufacture of various containers such as DI cans, food cans, and beverage cans.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples. However, the invention is not limited to the embodiments.

<Manufacture of plated steel sheets>

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

The steel plate (T4 original plate) having a thickness of 0.22 mm was subjected to electrolytic degreasing and pickling, and then tin plating of the Sn adhesion amount on each side shown in Table 3 was applied. Next, heat-melting treatment is applied to a temperature equal to or higher than the melting point of Sn to form an Fe-Sn alloy layer and an Sn layer on the upper layer, thereby producing a plated steel sheet. According to this, a plating layer made of an Fe-Sn alloy layer/Sn layer is formed on both sides in order from the lower layer side.

(K-2)

The steel plate (T4 original plate) having a thickness of 0.22 mm was subjected to electrolytic degreasing, and after forming a nickel plating layer on the Ni adhesion amount of each surface shown in Table 3 using a Watt bath, at 10 vol.% H ₂ + 90 vol.% N ₂ In the environment, the nickel plating bath was diffused and infiltrated at 700 ° C to form a Ni-Fe alloy layer (Ni-containing layer) on both surfaces (the Ni adhesion amount is shown in Table 3).

Next, tin plating having the Sn adhesion amount on each side shown in the third table was applied to the steel sheet having the Ni layer on the surface layer using a tin plating bath. With Thereafter, the temperature is equal to or higher than the melting point of Sn, and a heat-melting treatment is applied to form a Fe-Sn-Ni alloy layer and a discontinuous Sn layer on the upper layer to produce a plated steel sheet. According to this, a plating layer made of a Ni—Fe alloy layer/Fe—Sn—Ni alloy layer/Sn layer is formed on both sides in order from the lower layer side.

<Pre-treatment step (formation of tin oxide film)>

After the produced plated steel sheet is washed with water, the treatment liquid (solvent: water) in the composition shown in Table 1 (the first table), the treatment temperature (liquid temperature) shown in Table 2, and the immersion time or anodic electrolysis Conditions form a tin oxide film on both sides. Moreover, when the tin oxide film was not formed by the pretreatment step, it was described as "-" in the second table.

<film formation step>

Next, the plated steel sheet subjected to the pretreatment step is washed with water, and the treatment liquid (solvent: water) having the composition shown in Table 1 (the 2) and pH is used, and the treatment temperature (liquid temperature) shown in Table 2 is used. Cathodic electrolysis treatment is applied under electrolysis conditions (current density, energization time, and electric density). Subsequently, it was subjected to a water washing treatment, and dried at room temperature using a hair dryer to form a film on both sides.

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

The amount of reduction of the tin oxide film, the Ti adhesion amount of the film, and the Ni adhesion amount were measured and calculated by the above method.

<Exterior> Early Colors

The color of the brown color of the film was evaluated for the steel sheet for containers immediately after the production (within 60 minutes after the production). Specifically, the L value was measured using SQ-2000 manufactured by Nippon Denshoku Industries Co., Ltd., and evaluated based on the following criteria. When it is ◎ or ○, it can be evaluated that the coloration of the film is suppressed, and the appearance is excellent.

◎: L value of 75 or more

○: L value of 70 or more is less than 75

△: L value of 60 or more is less than 70

×: L value is less than 60

"Discoloration resistance"

The steel sheet for containers for evaluation of color tone was placed in a constant temperature and humidity chamber at 50 ° C and a relative humidity of 98% for 72 hours, and the L value was measured in the same manner as the initial color tone, and evaluated by the following criteria. When it is ◎ or ○, it can be evaluated that the coloring deepening is suppressed over time, and the appearance is excellent.

◎: The L value decreased from the initial stage (within 60 minutes after production) to less than 3

○: The L value from the initial stage (within 60 minutes after production) is reduced to 3 or less and less than 7

△: The L value from the initial stage (within 60 minutes after production) is reduced to 7 or more and less than 12

×: The L value from the initial stage (within 60 minutes after production) is reduced to 12 or more.

<Adhesiveness>

The epoxy phenol-based coating material was applied onto the surface of the produced steel sheet for containers (100 mm wide to 150 mm long), sintered at 210 ° C for 10 minutes, and applied at a coating amount of 50 mg/dm ² . Next, the above-mentioned coating was applied, and the two sheets of the container were produced under the same conditions, and the nylon backing film was sandwiched so that the coating was laminated so as to face the bonding, and the pressure was 2.94 × 10 ⁵ Pa at a temperature of 190 ° C. It is pressed under the pressure of 30 seconds. Subsequently, it was divided into test pieces of 5 mm width. The steel sheets for two sheets of the container in which the divided test pieces were peeled off were stretched by a tensile tester, and the tensile strength at the time of stretch peeling was measured. The average value of the two test pieces was evaluated for each test material on the basis of the following criteria. Practically, when the result is ○ or Δ, it can be evaluated as excellent in adhesion.

○: 2.0kgf or more

△: 1.0kgf or more and less than 2.0kgf

×: not up to 1.0kgf

As is understood from the results shown in the above Tables 1 to 3, it was confirmed that the steel sheets for containers of Examples 1 to 51 of the present invention were excellent in appearance.

Among them, the examples of the present invention in which the value of X is 38 or less are superior to the examples 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 amount of reduction of the tin oxide film was less than 2.0 mC/cm ² or more than 5.0 mC/cm ² were inferior in appearance.

Further, in the steel sheets for containers of Comparative Examples 2 to 4 in which the amount of reduction of the tin oxide film exceeds 5.0 mC/cm ² , it is considered that Sn is doped from the tin plating layer to the film due to the tin oxide film (hence, the X value is higher. Small), but since the tin oxide film itself is colored, the L value decreases, which is poor in appearance.

Claims (7)

A steel sheet for a container, comprising: a plated steel sheet covering at least a part of a surface of the steel sheet with a plating layer selected from at least one of a Sn layer, an Fe—Sn—Ni alloy layer, and an Fe—Sn alloy layer; a steel sheet for a container for a film on a surface of the plated steel sheet on the surface of the plating layer, a tin oxide film containing tin oxide between the plating layer and the film, and a quantity of electricity required for reduction of the tin oxide The film has a Ti content of 2.0 to 5.0 mC/cm ² and a Ti conversion amount of 2.5 to 30.0 mg/m ² on each side of the plated steel sheet. The steel sheet for containers according to claim 1, wherein the coating film contains Ni, and the Ni conversion conversion amount per side of the plated steel sheet is 0.1 to 20.0 mg/m ² . The steel sheet for containers according to claim 1 or 2, wherein the atomic concentration distribution of the zero-valent Sn is equal to 25% of the atomic concentration of the zero-valent Sn of the plating layer in the atomic concentration distribution in the depth direction from the surface of the film L (unit: nm), and the product X of the average atomic concentration A (unit: atomic %) of the zero-valent Sn from the surface of the film to the depth L satisfies the following formula (1), 0 ≦ X (= L × A) )≦60...(1). A method for producing a steel sheet for a container, which is obtained by the steel sheet for a container according to claim 1, and comprising the steps of: selecting at least one selected from the group consisting of a Sn layer, an Fe-Sn-Ni alloy layer, and an Fe-Sn alloy layer; a layer of plating covering at least a portion of the surface of the steel sheet The plated steel sheet is immersed in the treatment liquid containing the oxidizing agent or the carbonate, or is subjected to anodic electrolysis treatment in the pretreatment liquid to prepare the tin oxide film on the surface of the plating layer side of the plated steel sheet. And 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 has been formed to a cathodic electrolytic treatment in a treatment liquid containing a Ti component. A method for producing a steel sheet for a container obtained by the steel sheet for a container according to claim 2, comprising the steps of: including at least one selected from the group consisting of a Sn layer, an Fe-Sn-Ni alloy layer, and an Fe-Sn alloy layer a plated steel sheet covering at least a part of the surface of the steel sheet is immersed in a treatment liquid containing an oxidizing agent or a carbonate, or is subjected to anodic electrolysis treatment in the pretreatment liquid, thereby plating the plated steel sheet. a step of forming the tin oxide film on the surface of the layer side, and performing a cathodic electrolysis treatment on the plated steel sheet on which the tin oxide film has been formed in the treatment liquid containing the Ti component and the Ni component, and the tin oxidation treatment A film forming step of forming the foregoing film on the surface of the film. The method for producing a steel sheet for a container according to claim 4, wherein the oxidizing agent is selected from the group consisting of perchlorate, alkali metal or alkaline earth metal peroxide, and hydrogen peroxide or a derivative thereof. At least one of the foregoing carbonates is an alkali metal carbonate. The method for producing a steel sheet for containers according to any one of claims 4 to 6, wherein the amount of Sn deposited on each side of the steel sheet in the plating layer is 0.1 to 15.0 g/m ² .