JP3461684B2 - Manufacturing method of steel plate for laminated welding can - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a can-making material,
In particular, the present invention relates to a method for producing a steel plate for a laminated welded can, which is excellent in seam weldability, corrosion resistance, appearance, paint and film adhesion.

[0002]

2. Description of the Related Art In recent years, the technology for producing welded cans by the wire seam resistance welding method has made rapid progress, and its practical application in the field of beverage cans has made rapid progress. Steel plates for cans used in this kind of welded can are made by electroplating Fe-Ni alloy, then tin, and then tin-plated and chromate-treated. For seam welded cans having excellent paint adhesion and weldability by a method for producing a surface-treated steel sheet for use in manufacturing (Japanese Patent Laid-Open No. 60-208494), or after applying a Fe-Ni alloy, followed by tin plating and chromate treatment Method for producing surface-treated steel sheet (JP-A-60-13)
098 publication). Certainly, the manufacturing method according to the present invention provides a surface-treated steel sheet for a welding can having weldability, corrosion resistance, and paint adhesion. Further, using these surface-treated steel sheets for containers, paint baking is performed on the inner surface of the can to ensure corrosion resistance, and multicolor printing is performed on the outer surface of the can. After that, the cans are made by the wire seam welding method and put into practical use.

[0003]

In recent years, with the further advancement of can manufacturing technology and the cost reduction of cans, the aim is to greatly improve the productivity of the can manufacturing process, instead of painting and printing. , Materials in which an organic film is laminated on the inner surface and / or the outer surface of the can have come to be used. However, when the above-mentioned surface-treated steel sheet for a container is applied as a material for laminating an organic film on the inner surface and / or the outer surface of a can, paint or poor film adhesion occurs in the vicinity of the welded portion. This is because the above-mentioned surface-treated steel sheet for a container contains metallic tin that is not alloyed in the plating layer, so that the plating layer melts in the vicinity of the welded portion whose temperature is raised to the tin melting point or higher due to the residual heat of welding. At this time, the paint or film on the plating layer is in a state of floating on the molten liquid metal tin, so that the adhesion between the paint or film and the steel plate is extremely low, and the paint or film is peeled off by cooling air. The paint or film tends to contract due to the internal stress of the paint or film, resulting in poor adhesion of the paint or film.

[0004]

[Means for Solving the Problems] In order to avoid poor adhesion of paint and film, the amount of metal tin plating is reduced,
If the coverage of metallic tin is reduced, the paint and film adhesion will certainly improve. However, if the amount of tin plating decreases, the weldability and corrosion resistance, which are the characteristics that steel plates for welding cans have, are deteriorated. Therefore, for welding cans that satisfy all of film adhesion, weldability, appearance, and paint adhesion. The manufacture of the material was difficult. The present inventors have addressed these problems by
As a material for welding cans that satisfies all of the appearance, paint and film adhesion, weldability, and paint adhesion, a plating structure that exposes the nickel plating layer with excellent film adhesion, in which tin is spheroidized and metal tin is not present It has been found that the steel sheet possessed by the steel sheet can secure excellent adhesiveness even at a portion exceeding the melting point of tin, such as a heat-affected zone of welding, and has invented an economically superior method in its production.

The present inventors have developed a method for economically and efficiently producing a spherical tin-plated layer on a nickel-plated layer. Therefore, the temperature rising rate in the heat treatment performed after tin-plating affects the spheroidization of tin. The effect was studied carefully. as a result,
It was found that the spheroidization of tin was promoted when the heating rate was low. This is because when the temperature rising rate is low, the alloying of the plated tin and the base is performed slowly, so when the tin melts, the surface exposure of the tin alloy that hinders the spheroidization of tin is reduced, It is considered that the spheroidization of the molten tin was promoted.

That is, the present invention is: (1) ² to 200 mg / m ² of iron-nickel on the surface of a steel plate
Spherical tin with an area coverage of 40 to 98%, which is obtained by performing alloy alloy plating or nickel diffusion plating, then 400 to 2500 mg / m ² tin plating, and heating at a heating rate of 10 to 60 ° C./sec to melt tin. A method for producing a steel plate for a laminated welding can, which comprises forming a plating layer. (2) 2-200 mg / m ² of iron-nickel on the surface of the steel plate
Alloy plating or nickel diffusion plating, then 400 to 2500 mg / m ² tin plating, heating at a temperature rising rate of 10 to 60 ° C./sec to melt tin, and the area coverage rate exceeds 80% to 98%. A method for producing a steel plate for a laminated welding can, which comprises forming the following spherical tin-plated layer. (3) In the method for producing a steel sheet for laminated welded cans according to (1) above, a chromate coating layer having a Cr equivalent of ² to 40 mg / m ² is formed on the outermost surface layer.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a steel plate for a laminated welded can, which is the function of the present invention and is excellent in weldability, corrosion resistance, appearance, paint and film adhesion, will be described in detail below. In the present invention, the original plating plate is not particularly limited, and normally a steel plate used as a container material is used. The manufacturing method of the plating base plate, the material, etc. are not particularly limited, and from the ordinary billet manufacturing process to hot rolling, acid tip,
It is manufactured through processes such as cold rolling, annealing and tempering. Further, this plated original plate may be manufactured in a step of performing cold rolling, annealing and then re-cold rolling (that is, 2CR method) according to the required strength and plate thickness of the can.

When plating is applied to the above-mentioned plated original plate,
Usually, degreasing and pickling are performed as pretreatments for cleaning the surface of the plating original plate, but those methods are not particularly limited, and for example, degreasing is performed in 10% caustic soda and then in 5% sulfuric acid solution. A pickling treatment may be performed. Subsequent to degreasing and pickling, a nickel plating layer is provided to ensure the corrosion resistance that should be provided as a can material. Nickel is a metal that itself has excellent corrosion resistance, so the greater the amount of plating, the greater the corrosion resistance of the plated steel sheet.
Practically, the minimum nickel plating amount required to develop sufficient corrosion resistance is 2 mg / m ² . Therefore, the nickel plating amount needs to be ² mg / m ² or more.

On the other hand, since nickel is a metal which is extremely easily alloyed with tin, when the amount of nickel plating increases, alloying with the upper layer of tin proceeds in the can making process, and is necessary for industrially efficient welding. , Tin that is not alloyed is not sufficiently secured. Therefore, the nickel plating amount is 200 mg / m
Must be ² or less. The structure of the nickel plating layer in the present invention is not particularly limited. As the nickel plating layer, Fe-Ni alloy plating may be applied by electroplating to form the nickel plating layer. Further, even if pure nickel or Fe—Ni alloy plating is applied and then heated in an annealing furnace or the like to form a nickel plated layer in which nickel is diffused, the effect of the present invention is not impaired.

Tin plating is performed subsequent to nickel plating. The tin plating mentioned here is composed of metallic tin and inevitable impurities. Further, the tin plating method is not particularly limited, and for example, the electroplating method can be used. Tin plating is performed to secure weldability as described above, but in order to perform efficient welding industrially,
It is necessary to set the tin plating amount to 400 mg / m ² or more. When the tin plating amount is less than 400 mg / m ² , tin is alloyed by the heat treatment performed after the tin plating and the thermal influence of laminating, etc., and unalloyed tin necessary for welding cannot be sufficiently secured. Therefore, the amount of tin plating is 400m
It must be g / m ² or more. Weldability improves as the tin plating amount increases, but the plating amount is 400 mg / m ²
If it exceeds, the effect of improving the weldability is saturated. Therefore, economically expensive tin does not need to be plated in excess of 250 mg / m ² and may be 250 mg / m ² or less. This tin plating method is not particularly limited, and for example, ordinary electroplating can be used.

After the tin plating, the plated tin is melted by heat treatment to be spheroidized and immediately cooled below the melting point of tin,
A plating layer with excellent adhesion is formed. Sn at this time
The area occupancy rate of 40 to 98% is required. This is because Sn that has an excellent appearance when the area occupancy rate is less than 40%.
The area ratio is too small, resulting in poor appearance. Therefore, the area occupancy of Sn must be 40% or more. Also,
In order to exhibit more excellent appearance, it is sufficient to increase the area coverage of Sn, which has excellent appearance.
The area occupancy rate of is preferably more than 80%. On the other hand, the appearance of the steel sheet improves as the area occupancy of Sn increases, but if the area occupancy exceeds 98%, the adhesion of the film deteriorates, so the area occupancy of Sn should be 98% or less. There is a need.

The heat treatment conditions carried out for obtaining the above-mentioned spherical tin plating layer are defined as follows. That is, according to the above-mentioned essence of the present invention, the lower the heating rate,
Although the spheroidizing effect of tin is improved, in order to secure the area occupancy of tin exhibiting a good appearance, the temperature rising rate is 10 ° C /
It must be more than a second. This is because an excessively low temperature rise is economically disadvantageous because it leads to a decrease in productivity and an increase in the size of the heating unit device, and the heating time near the melting point of tin is long, and the alloying of tin is remarkable. This is because it progresses and the weldability deteriorates.

On the other hand, when the temperature rising rate is increased, the promotion of spheroidization of tin is weakened, the area occupancy rate is increased, and the appearance is improved, but the adhesiveness is gradually decreased, and practically excellent adhesiveness is secured. In order to achieve a tin spherical tin area ratio of 98% or less that can be achieved and can exhibit an excellent appearance, it is necessary to set the heating rate to 60 ° C./second or less. Therefore, in order to obtain the spherical tin area occupancy ratio (40% or more, preferably more than 80% and 98% or less) having both the above-described good adhesion and excellent appearance, the temperature rising rate is 10 ° C / sec or more. , 60 ° C./second or less. In the present invention, the heat treatment method is not particularly specified. In this treatment, it suffices to perform heat treatment exceeding the melting point of tin, and for example, methods such as electric heating, induction heating, and furnace heating may be used.

Further, it is necessary to immediately cool the molten tin after melting it. Immediately after melting, tin is spheroidized, but in the temperature range near or above the melting point of tin, alloying of tin and the underlying nickel plating layer proceeds rapidly. Due to the progress of alloying,
Since unalloyed tin that exhibits industrially stable weldability is reduced, it is desirable to cool immediately after the treatment according to the invention. Therefore, the faster the cooling rate is, the better, and cold water or hot water may be used for cooling. Subsequently, a chromate film is applied for the purpose of film adhesion and corrosion resistance (prevention of undercutting corrosion). The chromate film referred to here is a single film of hydrated chrome oxide, that is, the original chromate film and the other is a film consisting of a metallic chromium layer as the lower layer and a hydrated chromium oxide layer as the upper layer. Pointing to.

The hydrated chromium oxide layer may contain sulfate ions, fluorine ions, etc., which are plating aids described later. The film adhesion and corrosion resistance are ensured by the strong chemical bond between the functional group of the hydrated chromium oxide and the functional group of the film to be laminated. However, since the hydrated chromium oxide film is an electrically insulating material, it has a very high electric resistance, and since metallic chromium has a high melting point and a high electric resistance, both are negative factors that deteriorate the weldability. Therefore, it is very important to have good film adhesion and corrosion resistance and an appropriate amount of chromate film adhesion that does not practically deteriorate weldability. Therefore, the amount of chromate coating adhered is selected to be ² to 40 mg / m ² per one surface in terms of metallic chromium.

That is, the amount of chromate film adhered is 2 mg / m
^If it is less than ² , the effect of improving the film adhesion and preventing under-catering corrosion cannot be obtained, so 2 m
An adhesion amount of g / m ² or more is desirable. On the other hand, when the amount of the chromate coating adhered exceeds 40 mg / m ² , the contact resistance is remarkably increased, and scattering due to local heat generation is apt to occur and the weldability is deteriorated. Therefore, the amount of chromate film adhered is 40m
It is regulated to g / m ² or less. The chromate treatment method may be any method such as dipping treatment with an aqueous solution of various chromic acid sodium salts, potassium salts and ammonium salts, spray treatment, electrolytic treatment, and the like, but cathodic electrolytic treatment is particularly excellent. In particular, cathodic electrolysis treatment in an aqueous solution in which sulphate ions, fluoride ions (including complex ions) or a mixture thereof is added to chromic acid as a plating aid is the most excellent.

[0017]

EXAMPLES Examples and comparative examples of the present invention will be described below, and the results are shown in Table 1. By cold rolling or double rolling after annealing, the plating base plate adjusted to a predetermined plate thickness is electrolytically degreased in 5% caustic soda, washed with water and then electrolytically pickled in 10% sulfuric acid, and surface-treated after surface activation. It was This plating base plate is nickel-plated under the conditions (1)-(A) to (B) , and then tin-plated under the conditions (2), and then (3)-(A)-(B). (4)-(A) to (C), and a chromate film was produced in the treatment baths (4)-(A) to (C).

(1) Conditions for providing a nickel plating layer (A) Electric Fe-Ni alloy plating Ni ion: 25 g / l, Fe ion: 50 g / l, sulfate ion: 15 g / l, chlorine ion: 10 g / l, Boric acid: Fe-N by immersing the test piece in a plating bath of 35 g with 20 g / l and electrolyzing at 10 A / dm ^2.
An i alloy plating layer is formed. The electrolysis time is adjusted according to the plating amount.

(B) Nickel Diffusion Plating A nickel plating layer is formed at 780 ° C. for 30 seconds with 95% nitrogen.
-Heating in an atmosphere gas of 5% hydrogen to form a nickel diffusion layer. (2) Tin plating conditions Tin ion: 15 g / l, phenol sulfonate ion:
15 ° C. with 15 g / l, gloss additive: 1.2 g / l
Immerse the test piece prepared in (1) in the plating bath of
Tin plating is performed by electrolysis at / dm ² . The electrolysis time is adjusted according to the plating amount.

(3) Heat Treatment Conditions (A) Heating Furnace Method The tin-plated steel sheet prepared in (2) is placed in a heating furnace having an atmosphere of 400 ° C. for 5 to 30 seconds to melt and take out tin, and immediately cooled. (B) An alternating current is applied to the tin-plated steel sheet manufactured by the electric heating method (2) to generate heat by the electric resistance of the steel sheet to melt tin and immediately cool it. (C) The tin-plated steel sheet produced by the induction heating method (2) is heated by induction heating to melt tin and immediately cooled.

(4) Chromate treatment conditions The test piece prepared in (3) is immersed in a bath having the following plating composition for electrolysis. The electrolysis time is adjusted according to the plating amount. (A) Chromium oxide 100 g / l, sulfate ion 0.6 g
/ L Plating conditions 20 to 60 ° C, 5 to 80 A / dm ² (B) sodium dichromate 15 to 45 g / l Plating conditions 30 to 50 ° C, 10 to 40 A / dm ² (C) Chromic acid 80 g / l, sulfuric acid Ion 0.05 g /
1, sodium fluorosilicate 2.5 g / l, ammonium fluoride 0.5 g / l Plating conditions 15 to 75 ° C., 10 to 85 A / dm ²

Regarding the above-mentioned treated materials, the following (A) to
It carried out about each item of (E), and evaluated the performance. (A) The seam weldability test piece is assumed to be a coating baking condition of high temperature and short time.
Baking was performed under the condition that the temperature was raised to 0 ° C. in 23 seconds, and the seam weldability was evaluated under the following welding conditions. Lap fee 0.
5 mm, pressing force 45 kgf, welding wire speed 80
Welding is performed by changing the current under the condition of m / min, and it is comprehensive from the wideness of the appropriate current range consisting of the minimum current value at which sufficient welding strength can be obtained and the maximum current value at which welding defects such as scattering start to stand out. Judging from the above, there are 4 levels (◎: very wide,
◯: wide, Δ: practically no problem, x: narrow).

(B) Paint adhesion The surface of the test piece corresponding to the inner surface of the can is epoxyphenolic.
55 mg / dm of paint ²Apply and then correspond to the outer surface of the can
40 mg / dm of clear lacquer on the surface²Apply, 29
It was dried and hardened at 0 ° C. under a baking condition of 15 seconds. Pull
Continue to put scratches on each surface at 1mm intervals,
Make 100 squares, quickly peel off the tape, and
The peeling condition was observed in four stages (◎: no peeling at all, ○:
Very slight peeling, △: Slight peeling, ×: Most
The paint adhesion was evaluated by peeling).

(C) Film Adhesion Evaluation Test After laminating a PET (polyethylene terephthalate) film having a thickness of 15 μm on a test piece, a cross cut is inserted until the base metal is reached, and it is rapidly heated to 240 ° C.
Air gas of 5 kg / cm ² is vertically blown to the central part of the cross-cut in 4 steps (◎: No peeling at all, ○: Very slight peeling, △: Slight peeling, ×: Most peeling) The peeling condition of the film was evaluated.

(D) UCC (undercutting corrosion) evaluation test In order to evaluate the corrosion resistance of the surface of the test piece corresponding to the inner surface of the can,
A PET (polyethylene terephthalate) film having a thickness of 15 μm was laminated on the surface corresponding to the inner surface of the can.
After that, insert a cross cut until reaching the base iron, 1.5
% Citric acid-1.5% sodium chloride mixed solution was immersed in a test solution at 55 [deg.] C. for 4 days under open air. After the test, quickly remove the scratches and the flat surface with tape, and the corrosion situation near the scratch area, the pitting situation of the scratch area and the film peeling situation of the flat area are classified into 4 stages (◎: No peeling and corrosion is recognized No, ○: There is very slight peeling but no corrosion is observed, Δ: There is slight peeling and minute corrosion is observed, ×: Most of the peeling is observed and severe corrosion is recognized) Was evaluated.

(E) Appearance evaluation test White printed thickness 1 on the surface corresponding to the outer surface of the can.
A 5 μm PET (polyethylene terephthalate) type film was laminated, and the brightness of the color tone was evaluated in four levels (⊚: very bright, ◯: slightly bright, Δ: bright, x: dark). As shown in Table 1, it was revealed that the steel plate for laminated welded cans produced by the present invention had excellent weldability, appearance, paint adhesion, film adhesion, and corrosion resistance.

[Table 1]

[0027]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, as a can-making material, it is possible to economically produce a steel plate for a welded can which is particularly excellent in seam weldability, corrosion resistance, appearance, paint and film adhesion. It has an extremely excellent industrial effect.

Continuation of front page (56) Reference JP-A-4-41694 (JP, A) JP-A-7-76058 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 28 / 02 B32B 15/01 C25D 5/26 C25D 5/50 C23C 28/00

Claims (3)

(57) [Claims] 1. A steel sheet having a surface of ² to 200 mg / m ² of iron
-Nickel alloy plating or nickel diffusion plating, then 400-2500 mg / m ² tin plating, heating at a heating rate of 10-60 ° C / sec to melt tin, and spherical shape with an area coverage of 40-98%. A method for producing a steel plate for a laminated welding can, which comprises forming a tin-plated layer. 2. The surface of the steel sheet is 2 to 200 mg / m ² of iron
-Nickel alloy plating or nickel diffusion plating, then 400-2500 mg / m ² tin plating, heating at a temperature rising rate of 10-60 ° C / sec to melt tin, and the area coverage rate exceeds 80% to 98 % Or less of a spherical tin-plated layer is formed, a method for producing a steel plate for a laminated welded can. 3. The outermost layer has a Cr equivalent of 2 to 40 mg / m.
^2. The method for producing a steel plate for a laminated welding can according to claim 1, wherein the chromate coating layer of ² is formed.