JP3224457B2 - Material for welding cans with excellent high-speed seam weldability, corrosion resistance, heat resistance and paint adhesion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for a welding can having a film structure excellent in high-speed seam weldability, corrosion resistance, heat resistance and paint adhesion.

[0002]

2. Description of the Related Art In recent years, the practical use of seam welding cans represented by the pseudoronic method has been rapidly progressing. In order to cope with the expansion of the welding can process, various materials have been developed and put to practical use as materials for welding cans. The following materials have been developed as welding can materials. A material for a welding can which is formed on a steel sheet surface with a Ni plating layer of 150 to 2500 mg / m ² per side and a chromate coating layer of ² to 15 mg / m ^{2 in} terms of Cr (JP-A-5
No. 6-169788) Ni / Ni + Fe = 0.02-0.
Fe-Ni having a composition of 50 and a thickness of 10 to 5000 °
An alloy layer and a Sn-plated layer of 100 to 1000 mg / m ² were provided thereon, and reflow treatment was performed to obtain a Cr-converted amount of 5 to 5 mg / m ^2.
Method of providing a chromate coating layer of 20 mg / m ² (Japanese Patent Application Laid-Open No. Sho 60-17099)

First, Ni-plated / chromate-treated steel sheet is a TFS type welding can material that does not use Sn, has sufficiently good weldability for practical use, and has excellent heat resistance, paint adhesion and corrosion resistance after painting. It is in practical use in large quantities. In addition, a thin Sn plating type material (hereinafter referred to as “LTS”) having a Ni-based base treatment is made of soft, low-melting metal S after coating baking for the purpose of further improving weldability.
n (hereinafter referred to as “free-Sn”), and corrosion resistance can be ensured by a Ni-based base treatment, which has recently been put to practical use. All of these materials are excellent materials for welding cans having good weldability and corrosion resistance after painting, and are properly used depending on the intended use such as contents.

[0004]

In recent years, further progress in can-making technology and reduction in can-making cost have led to a reduction in the thickness of the raw material and an increase in the speed of paint baking and seam welding at high temperatures in a short time. Is strongly requested. That is, the thickness of the original plate material is reduced from the current plate thickness of 0.20 to 0.24 mm to 0.20.
mm is required, and in high-temperature short-time baking, the temperature is raised from the current baking conditions of 200 to 210 ° C. × 10 min to a temperature equal to or higher than the melting point of Sn (232 ° C.) in several tens of seconds. There is a strong demand for high-temperature short-time baking in which baking is performed. The speed of seam welding can be increased by 40 to 60 m / min.
It is planned to increase the wire speed from 70 to 100 m / min. However, when the above-mentioned known technique is applied to the conditions of thinning, high-temperature short-time baking and high-speed seam welding, the following problems occur.

[0005] First, the Ni-plated / chromate steel sheet has a problem that the suitable welding range in which a sufficient welding strength and a good welding appearance can be obtained becomes extremely narrow as the sheet thickness becomes thinner. This is a problem that the molten metal jumps out (hereinafter referred to as "scattering") before a sufficient welding strength is obtained due to an increase in welding current, resulting in deterioration of corrosion resistance and welding strength after painting. The Ni-plated / chromate-treated steel sheet can sufficiently cope with high-temperature short-time baking due to its good heat resistance, and can secure good corrosion resistance after painting.

On the other hand, in the LTS type material, the deterioration of weldability due to thinning can be avoided by controlling the amount of Sn plating corresponding to the inner and outer surfaces of the can. To exceed the melting point of Sn,
There is a problem that Sn of the surface layer is melted and the corrosion resistance after coating is significantly deteriorated. In order to address these problems, the present invention has a sufficiently wide suitable welding range when performing high-temperature short-time baking and high-speed seam welding, and has excellent paint adhesion and corrosion resistance after painting. It does not provide materials. In particular, the present invention exerts a very remarkable effect in ensuring good weldability when a thin material is used as a plating base sheet.

[0007]

Means for Solving the Problems The inventors of the present invention have studied an appropriate surface coating structure of a material for a welding can. As a result, the inventors have found that a wide suitable welding range in which sufficient welding strength can be obtained without spatter even during high-speed welding. It has been found that in order to ensure this, it is necessary to minimize the contact resistance between the welding electrode ring / material interface and the material / material interface. To reduce the contact resistance, the amount of free-Sn remaining after baking the paint is the most effective, but if free-Sn is present on the entire surface of the material, Sn
Since the plating layer is inferior in heat resistance, free-Sn is melted when baked at a high temperature for a short time, and it is difficult to secure good post-paint corrosion resistance.

The following means have been found to be the most effective in solving these problems and achieving both practical performance as a material for a welding can. That is, in order to reduce the contact resistance without completely melting the Sn plating layer by baking at a high temperature for a short time and causing remarkable deterioration of the corrosion resistance after coating, there is a great effect by making the Sn plating layer exist linearly. It turns out. Furthermore, it has been found that by providing a Ni plating layer having excellent heat resistance below the linear Sn plating layer, it is possible to sufficiently withstand high-temperature short-time baking and to secure good paint adhesion and corrosion resistance after painting. In other words, in order to ensure good weldability and good heat resistance enough to withstand high-temperature short-time baking, it is important to provide a linear Sn plating layer on the Ni plating layer on the steel sheet surface.

In order to ensure good paint adhesion and corrosion resistance after painting, a chromate coating layer must be provided on the linear Sn plating layer. Since the metal Cr to be formed has a high melting point, the chromate film is a negative factor for the weldability. For this reason, the chromate film must be regulated to the minimum necessary amount that can ensure good paint adhesion and corrosion resistance after painting. The present inventors have conducted a detailed study based on these ideas, and as a result, have excellent weldability, paint adhesion, and corrosion resistance after painting as a material for a welding can that is thin and can be baked at high temperature and short time. Was obtained.

The present invention has been made based on this finding, and the gist of the present invention is that the steel sheet has a surface of 2 to 2500 m per side.
g / m ² Ni plating layer, on which a width of 0.05 to
A linear Sn plating layer having a thickness of 100 μm, a plating amount of 10 to 2800 mg / m ² , and an area occupation ratio of 0.2 to 90% was formed thereon. Further, a chromate film of 1 to 50 mg / m ^{2 in} terms of Cr was formed thereon. An object of the present invention is to provide a material for a welding can excellent in high-speed seam weldability, corrosion resistance, heat resistance and paint adhesion.

[0011]

In the present invention, the original plate for plating is not particularly limited, and a steel sheet usually used as a container material is used. The production method and material of the original plating sheet are not particularly limited, and the production is performed through the steps of normal rolling of a slab, hot rolling, pickling, cold rolling, annealing, and tempering. Further, the original plate for plating may be manufactured by a process of performing cold rolling, annealing, and then re-cold rolling (that is, 2CR method) according to the required can body strength and plate thickness. First, a coating composition exhibiting good heat resistance and paint adhesion will be described.

As mentioned above, the required heat resistance is S
n is a high-temperature short-time baking that raises the temperature up to the melting point of n in several tens of seconds, and in order to withstand this baking condition and ensure good corrosion resistance after painting, plating of a metal having a melting point higher than at least Sn must be performed. No. In addition, not only heat resistance but also characteristics that do not impair good corrosion resistance, paint adhesion, and good weldability secured by the linear Sn plating layer must be provided.

The present inventors have made various studies and found that N
It has been found that these problems can be solved by applying an i-plated layer. That is, it has been found that by effectively utilizing the high melting point of 1450 ° C. of Ni metal, good heat resistance that can withstand high-temperature short-time baking can be exhibited, and good post-paint corrosion resistance and weldability can be ensured. In particular, it has been found that good weldability is exhibited by the excellent forgeability of Ni metal without impairing the good weldability obtained by the linear Sn of the upper layer. Forgeability is a property that, in addition to fully melting the metal during welding and exhibiting high welding strength, strong bonding strength can be obtained by hot pressing at high temperature without completely melting the metal. It is a metal with excellent forgeability.

The Ni plating layer is also important from the viewpoint of ensuring good corrosion resistance. Ni metal itself shows extremely good corrosion resistance, but when Ni plating is applied on a steel sheet, local cells of Fe and Ni are formed at the pinholes of the plating layer, and pitting corrosion occurs on the steel sheet because Fe dissolves I do. In other words, the point is to reduce pinholes in the Ni plating layer in order to ensure good corrosion resistance. Furthermore,
Regarding paint adhesion, good adhesion can be ensured at the portion where the chromate film is formed on the Ni plating layer where no linear Sn is deposited. The reason why it is difficult to secure good paint adhesion at the linear Sn deposition portion is that fragile tin oxide is generated in the paint baking portion, which is destroyed by damage such as can making and causes paint peeling. In the Ni plating layer, such a fragile oxide film is not formed, and good paint adhesion can be ensured.

The amount of Ni plating is regulated as an appropriate plating amount of ² to 2500 mg / m ² . If the amount of Ni plating is less than 2 mg / m ² , there are many pinholes in the plating layer, so that good corrosion resistance cannot be secured and good heat resistance cannot be secured. On the other hand, if the Ni plating amount exceeds 2500 mg / m ² , the effect of improving the corrosion resistance and heat resistance due to the decrease in the number of pinholes in the plating layer is saturated, and an economical disadvantage is generated. The method for applying Ni plating is not particularly limited, but a commonly used plating bath such as a Watts bath, a sulfuric acid bath, and a chloride bath is suitable.

Next, the function and effect of the coating composition capable of exhibiting good weldability will be described. Weldability does not cause scattering,
The wider the suitable welding range in which sufficient welding strength can be obtained, the better the weldability is evaluated. The electrode /
Reduction of the contact resistance at the material interface and the material / material interface is most effective. The reason is that if the contact resistance at the electrode / material and the material / material interface is high, current concentrates during welding, causing local heat generation and scattering. In other words, if the welding current is increased to secure the welding strength, scattering occurs in places where local heat is generated before sufficient welding strength is obtained, so there is no suitable welding range and Is evaluated as bad. On the other hand, when the contact resistance between the electrode / material and the material / material interface is low, local heat generation due to the concentration of current is unlikely to occur, and sufficient welding strength can be obtained without occurrence of scattering. Is evaluated as good.

Such a tendency of the seam weldability becomes remarkable especially in high-speed welding in which the welding speed is increased. That is, at the conventional wire speed of 40 to 60 m / min.
At such a low welding speed, there is an appropriate welding range even if the contact resistance is not so low. However, 70-100
When the welding speed is as fast as m / min, the amount of heat input per unit time increases, so that scattering easily occurs and the suitable welding range becomes narrow. In order to have a wide welding range even at the time of high-speed welding, it is necessary to further reduce the contact resistance. As described above, in order to reduce the contact resistance at the electrode / material and the material / material interface, it is not sufficient to use only the film configuration in which a chromate treatment is performed after Ni plating, which is a known technique. Sn on top of the layer
It has been found that applying the plating layer in a linear shape is very effective in reducing the contact resistance.

That is, as a film configuration capable of exhibiting good weldability, a film configuration in which Ni plating is first applied to the surface of a steel sheet, linear Sn plating is applied thereon, and a chromate film is further provided thereon is appropriate. The reason why the contact resistance can be reduced and good weldability can be secured by providing the linear Sn plating layer on the Ni plating layer is considered as follows.

(1) Since the soft Sn metal exists in the lower layer of the Ni plating layer, the contact area between the electrode ring / material and the material / material is increased by the pressing force applied from the electrode ring during welding, and the contact resistance is increased. Can be reduced in large quantities. (2) Since Sn metal has a low melting point, it is easily melted by the heat generated during welding, has a large effect of expanding the contact area between the electrode / material and the material / material, and has a small contact resistance, so that the local area during welding is reduced. Current concentration can be prevented.

In order to obtain the above-mentioned effects with a small amount of Sn plating, it is difficult to form a Sn plating layer with a normal smooth plating layer, and it is important to make the Sn plating layer linear. That is, since the Sn plating layer is entirely alloyed at the time of high-temperature and short-time paint baking in the smooth Sn plating layer, soft-low melting point free-Sn does not remain, and the effect of reducing the contact resistance cannot be exhibited. Since the alloying of the Sn plating layer proceeds in the height direction at the interface between the steel sheet and the Sn plating layer, the amount of free-Sn remaining when the linear Sn plating layer exhibits good weldability even after baking at high temperature and short time. Can be secured.

Therefore, in order to obtain good weldability,
Sn plating is applied, and the plating amount is 10 to 28.
00mg / m^Two Is regulated. This is linear Sn plating
The amount is 10mg / m^Two Less than alloy at high temperature and short time baking
Progress, and the free-Sn residual amount cannot be sufficiently secured.
Therefore, especially during high-speed welding with a large heat input per unit time
Good weldability cannot be exhibited. Also, linear Sn plating
2800mg / m ^Two Is exceeded, free-Sn remains
Effect is saturated and low melting point free-Sn
Since it remains too much, as described later, an Ni plating layer
High temperature baking to reach the temperature exceeding the melting point of Sn even if
In this case, the Sn metal melts and the corrosion resistance is significantly deteriorated.
You. In other words, heat resistance that can withstand high-temperature baking cannot be secured.
It becomes.

The width of the linear Sn plating is 0.05-1.
It is regulated to 00 μm. This is because the width of the plating layer is 0.0
If it is less than 5 μm, free-Sn does not remain due to the progress of alloying in the height direction by baking at high temperature for a short time, and good weldability cannot be secured. Further, if the width of the plating layer exceeds 100 μm, the effect of improving the weldability is saturated and the economical advantage is lost, and the heat resistance is deteriorated, so that the Sn metal is melted by high-temperature baking and the corrosion resistance after coating is deteriorated.

Furthermore, the area occupancy of the linear Sn plating is 0.1%.
It is regulated to 2-90%. This is because when the area occupancy of the linear Sn plating is less than 0.2%, the spread of the contact area between the electrode ring / material and the material / material due to the pressing force applied from the electrode ring during welding is reduced, and the contact resistance is reduced. Since the effect of reduction is low, good weldability cannot be secured. Therefore, it is necessary to regulate the area occupancy of the linear Sn plating to 0.2% or more. On the other hand, if the area occupancy exceeds 90%, the effect of improving the weldability is saturated and the economic merit is lost, and at the same time, the brittle tin oxide generated at the linear Sn deposits during high-temperature short-time baking degrades the paint adhesion. It is.

As described above, the suitable and economical plating amount of the linear Sn plating layer capable of satisfying both good weldability and heat resistance is 10 to 2800 mg / m ² , and the width is 0.05 to 100 μm.
m, the area occupancy is 0.2 to 90%. Although there is no restriction on the method of applying the linear Sn plating on the steel sheet, the following method is preferable. If Sn plating is performed at a low current density by applying a flow rate in a dilute acidic aqueous solution of Sn ²⁺ ions, a linear Sn plating layer can be formed on a steel sheet. For example, Sn ²⁺
The amount of ions is 0.1 to 3 in an acidic solution of 1 to 400 g / l.
It is desirable to perform Sn plating at a current density of 0 A / dm ² .

Subsequently, the plated steel sheet having such a coating layer is subjected to a chromate treatment for the purpose of improving paint adhesion and corrosion resistance after painting. The chromate coating prevents undercutting corrosion, in which the contents of the can pass through the coating and progresses under the coating on the inner surface of the can, and the so-called thread-like rust generated under the coating during storage on the outer surface of the can. It is effective in improving rust resistance such as filiform corrosion.

By forming such a chromate film, the adhesion of the film does not deteriorate over a long period of time, and good corrosion resistance and rust resistance are maintained. Further, the chromate film has a large effect of preventing blackening of the surface of a steel sheet, that is, blackening of sulfide, which is observed in foods containing sulfur compounds, such as fish meat and livestock products. As described above, the chromate film is particularly effective in improving the performance when it is used after being painted, but has a negative effect on the weldability. The chromate film referred to here is a single film of hydrated chromium oxide, that is, an original chromate film and another film consisting of a metal chromium layer as the lower layer and a chromium oxide hydrate layer as the upper layer. pointing. The hydrated chromium oxide coating has an extremely high electric resistance because it is an electrically insulating material, and chromium metal also has a high melting point and a high electric resistance. Therefore, both are negative factors that deteriorate the weldability.

Therefore, it is very important to have good coating performance and an appropriate amount of chromium adhering without practically deteriorating weldability. In the present invention, the amount of chromium attached is selected to be 1 to 50 mg / m ² per one surface in terms of metal chromium. That is, if the chromium adhesion amount is less than 1 mg / m ² , the effect of improving paint adhesion and preventing under-coating corrosion such as undercutting corrosion cannot be obtained, so that the chromium adhesion amount of 1 mg / m ² or more is desirable. On the other hand, the adhesion amount is 50 mg / m
^If it exceeds ² , the contact resistance will increase remarkably, scattering will easily occur due to local heat generation, and the weldability will deteriorate. Therefore, the amount of chromium adhering is regulated to 50 mg / m ² or less.

The chromate treatment may be carried out by any method such as immersion treatment with aqueous solutions of various sodium, potassium, and ammonium salts of chromic acid, spray treatment, and electrolytic treatment, and the cathodic electrolytic treatment is particularly excellent. Especially, SO ₄ ^2-ions to chromic acid, F ^- ions (including complex ions) or cathodic electrolytic treatment in an aqueous solution was added a mixture of them is the best. Although the concentration of chromic acid is not particularly limited, a range of 20 to 200 g / l is sufficient.

The amount of anions to be added is 1/30 of Cr ⁶⁺
When it is from 0 to 1/25, preferably from 1/200 to 1/50, the best chromate film is obtained. The amount of anions is Cr ⁶⁺
If it is 1/300 or less, a high quality chromate film which is uniform and uniform and greatly affects coating performance cannot be obtained. Also, 1 /
If it is 25 or more, the amount of anions incorporated in the formed chromate film increases, and the coating performance, especially the secondary adhesion of the coating, deteriorates. The anions to be added are added to the chromic acid bath in the form of sulfuric acid, chromium sulfate, ammonium fluoride, sodium fluoride compound and the like.

The bath temperature is not particularly limited,
The range of -70 ° C is an appropriate temperature range from the viewpoint of workability. A cathodic electrolysis current density in the range of 5 to 100 A / dm ² is sufficient. The treatment time was such that the chromium deposition amount was 1 to 50 mg as described above in any combination of the treatment conditions.
/ M ² .

The ratio between the metal chromium layer and the hydrated chromium oxide layer in the two-layer type chromate film is not particularly limited within the above-mentioned range of the adhesion amount, but is preferably in the range of 0.6 ≦ chromium oxide hydrate / chromium metal ≦ 3. . That is, when the amount of the hydrated chromium oxide is smaller than that of the chromium metal, the uniform coating property of the hydrated chromium oxide layer on the chromium metal layer is inferior, so that the paint adhesion tends to be deteriorated. On the other hand, when the hydrated chromium oxide layer is larger than the metal chromium layer, the anions and Cr ⁶⁺ ions contained in the hydrated chromium oxide layer are increased, and when exposed to a high-temperature environment after painting, these ions are reduced. It is not preferable because elution occurs and micro-swelling under the coating film, that is, a so-called blister easily occurs. Therefore, it is preferable to set the composition ratio between hydrated chromium oxide and metallic chromium in the range of 0.6 to 3 as described above.

Table 1 below shows the working materials and comparative materials for the examples of the present invention, and Table 2 shows the results. The cold-rolled or rolled twice after annealing, the plating original sheet adjusted to a predetermined thickness was electrolytically degreased in 5% caustic soda, washed with water, electrolytically washed with 10% sulfuric acid, and surface-treated after surface activation. . First, Ni plating is performed under the conditions shown in (1), then linear Sn plating is performed under the conditions shown in (2), and then the chromate film is formed in the processing baths shown in (3)-(A) to (C). What was produced was produced.

[0033]

[Table 1]

(1) Ni Plating Conditions Plating Bath Composition NiSO ₄ .6H ₂ O 75 g / l NiCl ₂ .6H ₂ O 140 g / l H ₃ BO ₃ 30 g / l Plating bath temperature 50 ° C.

(2) Linear Sn Plating Treatment Plating Bath Composition SnSO ₄ 10 to 30 g / l H ₂ SO ₄ 60 g / l Plating Bath Temperature 60 ° C. Current Density 0.1 to 30 A / dm ² (Electrolysis time is Sn plating amount The particle size of the linear Sn plating is adjusted by the amount of SnSO ₄ and the current density

(3) Chromate treatment bath (A) 100 g / l CrO ₃ SO ₄ ^2- 0.6 g / l (B) 24 g / l Na ₂ Cr ₂ O ₇ pH 4.5 (C) 80 g / l CrO ₃ SO ₄ ² -0.05 g / l Na ₂ SiF ₆ 2.5 g / l NH ₄ F 0.5 g / l For the above treated materials, the following items (A) to (G) were carried out, and their performance was performed. Was evaluated.

[0037]

[Table 2]

(A) Measurement of Contact Resistance The contact resistance, which greatly affects the seam weldability, was measured using a spot welding machine with CF electrodes. The test piece for measurement was baked under conditions in which the temperature was raised to 310 ° C. in 20 seconds, assuming that the coating was baked at a high temperature for a short time. A method for measuring contact resistance using a CF electrode is described below. The electrode used was made of chromium copper and had a tip diameter of 4.5 mmφ. Two test pieces were placed between the electrodes and 20
A constant current of 1 A is applied between the electrodes in a state of being pressurized to 0 kgf, and the voltage drop between the electrodes / electrodes, between the electrodes / steel plates, and between the steel plates / steel plates at that time is measured by a nanovolt meter to obtain a cold voltage. The static resistance was determined.

(B) Seam Weldability The test piece was prepared under the conditions of baking at high temperature and short time.
Baking was performed under the condition of raising the temperature to 0 ° C. in 23 seconds, and the seam weldability was evaluated under the following welding conditions. Lap fee 0.
5mm, pressure 45kgf, welding wire speed 80
Welding is performed under the conditions of m / min while changing the current, and the width of the appropriate current range including the minimum current value at which sufficient welding strength can be obtained and the maximum current value at which welding defects such as scatter become noticeable, and welding defects. Was evaluated comprehensively based on the occurrence status of the problem.

(C) Cross-cut test The surface of the test piece corresponding to the inner surface of the can was epoxyphenol-based.
55mg / dm of paint ^Two Apply, and also correspond to the outer surface of the can
40mg / dm of clear lacquer on the surface^Two Apply, 29
It was dried and hardened under baking conditions up to 0 ° C. for 15 seconds. pull
Then, scratch each surface at 1mm intervals, a total of 1
Make 00 grids, peel off the tape immediately,
The peeling state was evaluated.

(D) UCC (Undercutting Corrosion) Evaluation Test In order to evaluate the corrosion resistance after painting of the surface of the test piece corresponding to the inner surface of the can, an epoxyphenol (phenol-rich) paint for the can was coated on the surface corresponding to the inner surface of the can. 50mg / dm per side
^{2 was} applied and baked under the condition of raising the temperature to 310 ° C. in 18 seconds. Thereafter, a scratch was made so as to reach the iron surface of the coated plate, and the plate was immersed in a test solution, which was a mixture of 1.5% citric acid and 1.5% salt, at an open air value of 55 ° C for 4 days. After the test is completed, the scratch part and the flat part are immediately peeled off with a tape, and the undercoat corrosion state near the scratch part, the pitting state of the scratch part, and the peeling state of the flat part are judged and comprehensively evaluated. did.

(E) Sulfuration-resistant blackening test The same coating as in (D) was applied to the surface corresponding to the inner surface of the can.
The test piece subjected to the t-bending was placed in a commercially available product obtained by homogenizing boiled mackerel, and subjected to a retort treatment at 115 ° C. for 90 minutes. After the test, the blackened state of sulfide in the bent portion and the flat portion was evaluated.

(F) Filiform Corrosion Test In order to evaluate the fibrous mackerel property of the surface corresponding to the outer surface of the can, a clear lacquer was applied at 40 mg / dm ² ,
Drying and curing were performed under baking conditions in which the temperature was increased in 7 seconds. Continue to scratch with a knife until it reaches the iron surface,
Spray 5% salt water for 1 hour at 25 ° C.
It was left for 2 weeks at 85 ° C. and a relative humidity of 85% to evaluate the filiform rust.

(G) Actual can test An epoxyphenol-based test piece was applied to the surface of the test piece corresponding to the inner surface of the can.
55mg / dm of paint ^Two Apply, and also correspond to the outer surface of the can
40mg / dm of clear lacquer on the surface^Two After applying,
Dry and harden under baking conditions to raise the temperature to 320 ° C in 22 seconds
It has become. Then, the can body was manufactured using a seam welding machine.
Repair the weld with epoxy resin, and replace with orange juice.
After filling the cola, tighten the can lid made of $ 25 tin, 38
Stored at 12 ° C for 12 months. After the test, remove the contents
Iron elution amount and corrosion state on the inner surface side of the can (flat and welded)
Was observed.

[0045]

As described above, according to the present invention, when performing high-temperature short-time baking and high-speed seam welding, it has a sufficiently wide suitable welding range, and is excellent in corrosion resistance, heat resistance and paint adhesion. An object of the present invention is to provide a material for a welding can.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-133398 (JP, A) JP-A-60-17100 (JP, A) JP-A-60-56074 (JP, A) JP-A 60-56074 208494 (JP, A) JP-A-4-128386 (JP, A) JP-A-4-247897 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C25D 11/38

Claims (1)

(57) [Claims] 1. The steel sheet has a surface of 2 to 2500 m per side.
g / m ² Ni plating layer, on which a width of 0.05 to
A linear Sn plating layer having a thickness of 100 μm, a plating amount of 10 to 2800 mg / m ² , and an area occupation ratio of 0.2 to 90% was formed thereon. Further, a chromate film of 1 to 50 mg / m ^{2 in} terms of Cr was formed thereon. A material for welding cans with excellent high-speed seam weldability, corrosion resistance, heat resistance and paint adhesion.