JPH07138791A - Production of tin plated steel sheet excellent in glossiness and producing equipment therefor - Google Patents

Abstract

PURPOSE:To provide a producing method and device for a tin plated steel sheet excellent in surface glossiness without using reflow treatment. CONSTITUTION:The tin 0.1-2.8g/m<2> in coating weight is plated by dipping a steel strip after being annealed in an aq. solution containing >=0.01wt.% organic acid and next, applying refining rolling or a 2nd cold rolling. The producing equipment is constituted by placing a continuous annealing furnace, a pickling equipment, a refining rolling equipment, and a tin plating equipment in this order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a tin-plated steel sheet and manufacturing equipment.

[0002]

2. Description of the Related Art Electric tin plated steel sheets are widely used as materials for cans such as beverage cans and gallon cans, and the manufacturing process thereof is cold rolling, annealing, temper rolling or second cold rolling to obtain electric tin. It is generally tin-plated in a tin-plating facility. In the electric tin plating equipment, so-called reflow treatment is performed to raise the temperature of the steel plate after tin plating to a temperature equal to or higher than the melting point of tin to melt the electrodeposited tin, and further quench treatment is performed to dip the molten tin in hot water and solidify it. There are cases. By this reflow and quench treatment, a beautiful glossy surface, which is one of the features of tin-plated steel sheets, can be obtained.

On the other hand, the manufacturing cost of tin-plated steel sheet is lowered,
Proposals have been made to make the manufacturing process continuous in order to shorten the lead time. Japanese Unexamined Patent Publication (Kokai) No. 4-32559 discloses an equipment row in which these equipments are arranged in series in order to combine the steps of continuous annealing, temper rolling, and tin plating, which have been conventionally performed separately. .

[0004]

However, when a tin-plated steel sheet is to be reflow-quenched at a high speed, a surface defect called quench-stain poses a problem.
Quenching Sten is a phenomenon in which when a steel sheet is cooled in warm water, an abnormal boiling phenomenon occurs at the steel sheet interface, and due to this impact, molten tin solidifies while being irregularly distorted. It has a trace-like appearance. In general, it is more difficult to obtain a steel sheet surface without quenching as the sheet passing speed is higher, and in order to obtain a steel sheet surface without quenching stainless, the sheet passing speed must be reduced. That is, it was one of the main factors that reduce the productivity of tin-plated steel sheets.

In order to prevent quench-stain, for example, at a position before the tin-plated steel sheet reflowed in Japanese Patent Publication No. 54-36976, enters the quench tank, the spray cooling liquid is uniformly sprayed from the slit spray nozzle over the entire width. Although it is disclosed that it is applied, the boiling phenomenon occurring on the surface of the steel sheet is complicated and cannot be sufficiently analyzed, so that it is the current situation that it cannot be overcome yet.

Further, even when the tin-plated steel sheet is manufactured by the equipment disclosed in the above-mentioned Japanese Patent Laid-Open No. 4-32559, the ability of continuous annealing, temper rolling and tin plating (Ton / Hr In many cases, the reflow / quenching treatment capacity is significantly inferior to that of (1), and in such a case, the reflow / quenching treatment rate limits the overall facility capacity.

That is, even if the number of steps is minimized and the lead time is shortened, there is a large dilemma that the manufacturing cost is increased because the processing capacity is low. The present invention solves the above-mentioned problems and easily manufactures a tin-plated steel sheet having a beautiful and stable glossy surface even at a high speed, particularly a continuous annealing, temper rolling, and tin plating integrated facility. It is an object of the present invention to provide a method for producing a tin-plated steel sheet and a facility therefor for obtaining a beautiful glossy surface without limiting the rate of other processes.

[0008]

According to the present invention, in order to obtain a beautiful glossy surface, the annealed steel strip is immersed in an aqueous solution containing 0.01 wt% or more of an organic acid, and then temper-rolled or second-cooled. It is a method for producing a tin-plated steel sheet that is subjected to hot rolling and further tin-plated on at least one side, and the preferable basis weight of tin plating is 0.1 to 2.8 g / m ² , and the present invention is a continuous annealing furnace, pickling. The equipment is a tin-plated steel sheet manufacturing equipment in which equipment, temper rolling equipment, and tin-plating equipment are arranged in series in this order.

[0009]

The present inventors have focused on improving the color tone / gloss of the tin plate in order to achieve the purpose of the previous term. That is, the surface of the steel strip after annealing is shown in Fig. 3 (a), which is the result of measurement by the glow discharge spectrum method (GDS). The components such as Si and Mn in the steel are concentrated in the surface layer. The material clogging the work roll of the skin pass, and the fine irregularities of the concentrated material are transferred to the steel strip, resulting in a white and cloudy surface.

According to the present invention, the annealed steel strip is immersed in an aqueous solution containing 0.01 wt% or more of an organic acid, then temper-rolled or second cold-rolled, and at least one side is tin-plated. is there. By immersing the steel strip in an aqueous solution containing an organic acid, the concentrate on the surface of the steel strip is removed as shown in FIG. 3 (b), and a steel strip having no white cloudiness and excellent in color tone and gloss can be obtained. When 0.1 to 2.8 g / m ² tin plating is desirably applied to such a steel strip, a steel strip having a sufficiently excellent color tone and gloss can be easily obtained without performing reflow treatment.

The organic acid used in the present invention includes formic acid,
Suitable are linear aliphatic acids such as acetic acid, oxalic acid, propionic acid, and succinic acid, and oxyacids such as citric acid, lactic acid, gluconic acid, and tartaric acid. In the present invention, the concentration of the organic acid is 0.
Less than 0.01 wt% is limited to less than 0.01 wt% Mn
Is not sufficiently removed, and the effect of improving the color tone and gloss is insufficient. On the other hand, the upper limit is not particularly limited, but if the concentration is too high, a washing device for washing is required and the equipment cost is high,
Moreover, it is not preferable because the production line becomes long,
1% or less is usually sufficient.

Further, in the present invention, the tin deposition amount is 0.1
A range of up to 2.8 g / m ² is desirable. The reason is as follows. 1) When the amount of deposited tin is less than 0.1 g / m ² , the tin plating effect is not sufficiently obtained and the corrosion resistance is poor. 2) When the amount of tin deposited exceeds 2.8 g / m ² , no matter how excellent the color tone and gloss of the plating base plate is, the color tone after plating becomes whitish and sufficient color tone and gloss cannot be obtained without reflow treatment.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0014]

EXAMPLE FIG. 2 schematically shows the equipment arrangement of the continuous annealing / surface treatment equipment of the present invention. In FIG. 2, the steel strip that has left the continuous annealing furnace 1 passes through the light pickling equipment 2 and the dryer 3, passes through the intermediate looper 4, and passes through the skin pass equipment 5.
Is temper-rolled or cold-rolled, and then plated through a tin plating facility 7 via an intermediate looper 6 and wound on a winding reel 8.

FIG. 1 shows the relationship between the acid concentration and the color tone (L value: JIS Z8729) of a tin-plated steel sheet manufactured using the equipment row shown in FIG. Low carbon Al killed steel was used as the tin plate and continuous annealing was performed at a maximum reached plate temperature of 820 ° C. Formic acid with various concentrations was used for the light pickling. In this case, formic acid
The pH was 2.7 at 0.05 wt%. The immersion time was 1 sec, and the basis weight was 1.1 g / m ² after temper rolling with an elongation of 1.5%.
Tin plating was performed. FIG. 1 shows the result.

As is apparent from FIG. 1, the acid concentration is 0.01 wt%.
As a result, a steel sheet having a sufficiently glossy surface was obtained, and its color tone was almost the same as that of the case where reflow treatment was performed without pickling.

[0017]

EFFECTS OF THE INVENTION According to the present invention, since the color tone / gloss of the tin plate is improved, it is possible to rapidly and easily produce a steel strip having a color tone / gloss equivalent to that in the case of performing the reflow treatment. It was Further, unlike the reflow treatment, energy for heating the steel sheet is not required, so that the effect of reducing the manufacturing cost is great.

Further, when a new electric tin plating line or the like is constructed in the future, if the upper limit of the amount of tin deposited on the tin-plated steel sheet produced there is 2.8 g / m ² or less, the reflow equipment will not be required. It is expected that the construction cost will be significantly reduced.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between acid concentration and color tone (L value) after tin plating.

FIG. 2 is a schematic diagram showing an equipment row in the continuous annealing-surface treatment equipment of the present invention.

FIG. 3 is a GDS measurement diagram showing a surface concentrated state before temper rolling in the conventional method and the method of the present invention.

[Explanation of symbols]

 1 Continuous annealing furnace 2 Pickling equipment 3 Dryer 4 Intermediate looper 5 Skin pass equipment 6 Intermediate looper 7 Tin plating equipment 8 Take-up reel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Himeno 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Works (72) Inventor Fumio Furukaku, Kawasaki-cho, Chuo-ku, Chiba-shi Chiba Steel Works, Ltd.

Claims (3)

[Claims] 1. An annealed steel strip is immersed in an aqueous solution containing 0.01 wt% or more of an organic acid, then temper-rolled or second cold-rolled, and at least one side is tin-plated. A method for producing a tin-plated steel sheet having excellent luster. 2. The method for producing a tin-plated steel sheet having excellent luster according to claim 1, wherein the basis weight of tin plating is 0.1 to 2.8 g / m ² . 3. A continuous annealing furnace, pickling equipment, temper rolling equipment,
Equipment for manufacturing tin-plated steel sheets, characterized in that the tin-plating equipment is arranged in series in this order.