JPH05123772A - Surface treated steel sheet for di can having excellent adaptability as printing substrate - Google Patents

Abstract

PURPOSE:To obtain the surface treated steel sheet having the excellent adaptability to a printing substrate and high merchandise value by forming the surface treated steel sheet for DI cans which has graphite fluoride particles on the Sn plating layer on at least one layer of the steel sheet and has the excellent adaptability to the printing substrate. CONSTITUTION:After the steel sheet is subjected to degreasing and pickling, the steel sheet is subjected to the Sn plating of a prescribed thickness in an acidic Sn plating bath and is subjected to a treatment for coating with the graphite fluoride particles after washing. The Sn plated steel sheet mentioned above is immersed into an aq. soln. of various low temp. dispersed with the graphite fluoride particles of prescribed grain sizes and is dried by hot air after squeezing with rolls. The graphite fluoride particles are sized 0.01 to 10g/mm<2>. Further, the diameter of graphite fluoride particles is in a range of 0.1 to 10mum. As a result, the surface treated steel sheet for production of the DI cans which has the excellent adaptability to the printing substrate after DI working and has the high merchandise value is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated steel sheet for a DI can which has an excellent suitability for a printing base on the outer surface of the can after DI processing.

[0002]

2. Description of the Related Art A two-piece can is roughly divided into a squeeze (Dra
Wing) followed by ironing (Ironing) to integrally mold the can body and bottom, and a DID that forms only the body and bottom by drawing.
There are cans (or Dr cans), and the surface-treated steel sheet is prized for these purposes. Among them, in the DI can, the plating layer on the surface of the steel plate is considerably damaged due to the die being rubbed against the surface of the steel plate during the can body forming process and the deformation of the material accompanying the process. Conventionally, Sn-plated steel sheets, that is, tinplate, have been favored for DI cans, and the reason is mainly the work lubricity of Sn. That is, the lubricity of Sn has an important meaning in order to avoid problems such as flaws caused by insufficient lubrication of the die and the steel sheet during processing, cracks in the steel sheet, and the like. However, as described above, damage to the plated layer due to processing is unavoidable, and the Sn plated layer after processing is
The continuity is lost and the base steel is exposed.

[0003] On the other hand, the DI can is generally subjected to multicolored printing in order to enhance the display effect at the store, and after processing, it has an underlayer that makes these various prints vividly stand out. It is necessary and the background must be bright in order to bring out various colors vividly. In other words, the absorption of light by the base must be suppressed as much as possible. In the case of tinplate used in DI cans, the lubricity during processing is excellent, but the uniformity of the Sn plating layer after processing is inferior, and the base steel is largely exposed.

[0004]

[Table 1]

According to the research conducted by the present inventors, as shown in Table 1 above, when comparing the brightness of iron as a printing base with that of Sn, it was found that iron was significantly inferior. Therefore, suppressing iron exposure after processing as much as possible is a shortcut to improve suitability for printing substrates, but when Sn is used as the plating layer, it moves easily on the surface of the steel plate due to its lubricity due to its lubricity. Then, the bare steel is exposed.

[0006]

The present invention has been made to advantageously solve the drawbacks of tinplate.

[0007]

The gist of the present invention is as follows. (1) A surface treated steel sheet for a DI can which has fluorinated graphite particles on the Sn plating layer on at least one surface of the steel sheet and has excellent suitability for a printing substrate. (2) The surface-treated steel sheet for DI can having excellent suitability for printing base according to the above item 1, wherein the amount of fluorinated graphite particles is 0.01 to 10 g / m ² .

(3) Fluorinated graphite has a particle size of 0.1 to 10
The surface-treated steel sheet for DI cans having excellent printing base suitability according to the above 1 or 2 having a thickness of μm. On the outer surface of the DI can using tin plate (immediately after DI processing), Sn is discontinuously distributed in an island shape as shown in FIG. This occurs because Sn on the surface of the steel sheet is moved mainly to the concave portions according to the unevenness of the base steel due to the friction between the die and the steel sheet surface during DI processing, and the movement of Sn during the DI processing is It can be considered that Sn is unavoidable as long as it functions as a lubricant between the die and the base steel.

Therefore, in order to suppress the exposure of the base steel after DI machining, the load as a lubricant applied to Sn may be reduced by improving the lubricity by another means. The present inventors have found that the fluorinated graphite particles have good slipperiness, do not adhere to the die, and have the function of improving the lubricity during DI processing. It was confirmed that the load on the Sn as a lubricant can be reduced by applying it, and the present invention is constructed based on this finding.

The reason why the fluorinated graphite particles improve the lubricity is not clear, but since the molecular structure thereof is layered as shown in FIG. 2, it is broken into layers with relatively low energy and the friction coefficient of the interface is reduced. It is presumed that As the fluorinated graphite, there are (C ₃ F) _n type ones in addition to the (CF) _n type ones shown in FIG. 2, but the effects of the present invention are the same without any change.

The amount of fluorinated graphite is 0.01 to 10 g / m ^2.
Is appropriate. If it is less than 0.01 g / m ² , the lubricating effect may be insufficient, and if it exceeds 10 g / m ² , the lubricating effect is saturated and no further effect can be expected, which is economically disadvantageous. The particle size of the fluorinated graphite particles is preferably 0.1 to 10 μm. If the particle size is less than 0.1 μm, the lubricating effect is insufficient, and if it exceeds 10 μm, the adhesion to the surface of the steel sheet is poor and it becomes difficult to secure a predetermined coating amount.

A suitable Sn plating amount is 0.5 to 5 g / m ² . As described above, the fluorinated graphite particles greatly improve the DI processing lubricity, but the DI processing with the particles alone is somewhat unreasonable, and a slight lubricating effect due to Sn is inevitably necessary. When Sn plating amount is less than 0.5 g / m ^2, there is a risk of causing a problem of scratches containing such to die during continuous DI can manufacturing insufficient DI processing lubricity of the total is, 5 g / m ² than in It is disadvantageous because the lubricating effect is saturated and the economic loss is large.

The Sn plating layer of the present invention and the plating layer structure composed of the fluorinated graphite particles as the upper layer are required at least on the steel plate surface on the outer surface side of the can after the processing of the DI can, for the reasons described above. The other surface, that is, the surface corresponding to the inner surface side of the can after DI processing, is not always necessary, but there is no particular problem if it is advantageous to provide the plating layer structure for manufacturing reasons or the like.

The method of Sn plating does not require a special method, and a usual method such as acidic Sn is used.
A cathode electrolysis method in a plating bath, a so-called ferrostane bath may be used. The method of applying the fluorinated graphite particles is not particularly limited, and a method of applying the solution in which the particles are dispersed in water with a surfactant to the Sn-plated steel sheet and drying it may be used.

[0015]

EXAMPLES Next, examples of the present invention are listed in Table 2 together with comparative examples. The method of manufacturing the test materials listed in Table 2 is as follows. A steel plate having a plate thickness of 0.25 mm and a temper degree of T-4 is degreased and pickled by a conventional method, and then a known acidic S is used.
n plating bath, so-called ferrostane bath (40 ° C.), Sn plating with a predetermined thickness at a current density of 20 A / dm ² ,
After washing with water, the following fluorinated graphite particle coating treatment was performed.

(1) 5w of fluorinated graphite particles having a particle size of 2 μm
The Sn-plated steel sheet (Sn1.5 g / m ² ) was dipped in an aqueous solution of t% dispersed at a temperature of 20 ° C., rolled and squeezed, and then dried with warm air. (2) The Sn-plated steel sheet (Sn) in an aqueous solution at a temperature of 20 ° C. in which 10 wt% of fluorinated graphite particles having a particle diameter of 2 μm are dispersed
3.0 g / m ² ) was soaked, and after squeezing the roll, it was dried with warm air.

(3) The above Sn-plated steel sheet (Sn3.0 g / m ² ) was immersed in an aqueous solution at a temperature of 20 ° C. in which 4 wt% of fluorinated graphite particles having a particle diameter of 0.2 μm were dispersed, and after squeezing with a roll, warm air was blown. Dried. (4) The Sn-plated steel sheet (Sn0.
8 g / m ² ) was dipped, rolled and squeezed, and dried with warm air.

As a comparative example, a Sn-plated steel sheet was prepared by applying the following fluorinated graphite particle coating treatment. (Comparative Example 1) 0.5 wt% of fluorinated graphite particles having a particle size of 2 μm
The Sn-plated steel sheet (Sn 4.5 g / m ² ) was immersed in an aqueous solution having a temperature of 20 ° C. and dispersed at a temperature of 20 ° C., rolled, and then dried with warm air.

Comparative Example 2 The above Sn-plated steel sheet (Sn3.0 g / m ² ) was dipped in an aqueous solution at a temperature of 20 ° C. in which 5 wt% of fluorinated graphite particles having a particle diameter of 0.05 μm were dispersed, and after squeezing with a roll. Dry with warm air. (Comparative Example 3) 5 wt% of fluorinated graphite particles having a particle size of 20 μm
The above Sn-plated steel sheet (Sn 2.0 g / m ² ) was immersed in the dispersed aqueous solution at a temperature of 20 ° C., rolled, and dried with warm air.

(Comparative Example 4) The above Sn was placed in an aqueous solution at a temperature of 20 ° C. in which 10 wt% of fluorinated graphite particles having a particle diameter of 2 μm were dispersed.
A plated steel sheet (Sn 0.2 g / m ² ) was dipped, rolled, and dried with warm air. The following process was also performed as another comparative example. (Comparative Example 5) The above Sn-plated steel sheet (Sn 2.5 g) was added to an aqueous solution of sodium dichromate 30 g / liter having a bath temperature of 40 ° C.
/ M ² ) was dipped for 5 seconds, squeezed by a roll, and dried.

The coating amount was measured by determining the Sn plating amount from the Sn concentration by an atomic absorption method after dissolving the plating layer with 1N hydrochloric acid, and the fluorinated graphite particle amount before and after particle removal by ultrasonic cleaning in ether. It was calculated from the change in weight. As a lubricity index, the coefficient of friction on the surface of the steel sheet after the treatment was measured. The DI processing was performed for so-called φ211 (can diameter 66 mm) for 350 ml cans. With respect to the outer surface of the can after DI processing, the iron exposure index and the brightness after printing were evaluated.

* 1: Method of measuring friction coefficient The friction coefficient was measured with a Bowden type friction tester. Load is 500
The sample feed rate was 10 cm / min. * 2: Method of measuring the iron exposure index on the outer surface after DI processing. The outer surface of the can after DI processing is EPMA (Electron P
The exposure status of iron was analyzed by a line analysis of robe for micro analysis (Line Analysis). As shown in FIG. 3, iron is strongly detected in the part where the iron is exposed. For quantification, a line was drawn at the 50% level of the maximum detected intensity, and the percentage of the detected intensity portion of 50% or more was expressed in%. The beam diameter of EPMA was 2 μm, and 500 μm was analyzed per sample.

* 3: Method for measuring the brightness of the outer surface after DI processing after printing The outer surface of the can after DI processing was cut out and flattened, and 30 mg / dm ² (dry weight) of a commercially available white ink for can outer surface was used.
After printing and printing, the L value (L value of the Hunter color system Lab) was measured with a spectrophotometer and used as an index of brightness. A larger L value means brighter.

[0024]

[Table 2]

[0025]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to provide a surface-treated steel sheet for producing a DI can having a high commercial value and having an excellent suitability for a printing base on the outer surface after DI processing, which is industrially large It is effective.

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph showing a metal structure of an outer surface of a DI can using a tin-plated steel plate (tin plate).

FIG. 2 is an explanatory diagram showing a molecular structure of fluorinated graphite.

FIG. 3 is an explanatory diagram showing iron detection strength.

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Claims (3)

[Claims] 1. A DI having excellent fluorinated graphite particles having Sn-plated layer on at least one surface of a steel sheet and having excellent printing substrate suitability.
Surface-treated steel plate for cans. 2. The amount of fluorinated graphite particles is 0.01 to 10 g /
The surface-treated steel sheet for DI cans having excellent suitability for printing base according to claim 1, wherein the surface treated steel sheet is m ² . 3. The surface-treated steel sheet for a DI can excellent in suitability for printing base according to claim 1 or 2, wherein the particle diameter of fluorinated graphite is 0.1 to 10 μm.