JPH0657491A - Welded can material excellent in high-speed seam weldability, heat resistance and coating adhesion - Google Patents

Abstract

PURPOSE:To enhance the stability and excellent characteristics such as weldability and corrosion resistance by successively forming specified Ni plating layer, Sn plating layer and chromate coating film on the surface of a steel sheet. CONSTITUTION:An Ni plating layer is provided on the surface of a steel sheet at 150-2500mg/m<2> per side. An Sn plating layer is furnished thereon with the Sn plating grains having 0.2-12.0mum diameter interspersed at 400-2800mg/m<2>. A chromate coating film is formed thereon at 1-50mg/m<2> expressed in terms of chromium. A welded can material excellent in coating adhesion is provided in this way.

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 coating composition excellent in high speed seam weldability, heat resistance and paint adhesion.

[0002]

2. Description of the Related Art In recent years, the seam welding can manufacturing method represented by the pseudoronic method has been rapidly put into practical use. In order to cope with the expansion of the welding can manufacturing method, various materials for welding cans have been developed and put into practical use. The following materials have been developed as welding can materials. (1) 150 to 2500 mg / m per surface of steel plate
No. ² Ni plating layer and a chromate coating layer of ² to 15 mg / m ^{2 in} terms of chromium (Japanese Unexamined Patent Publication No. 56-169788) (2) Ni / Ni + Fe on steel plate in weight ratio = 0.02-
Fe-with a composition in the range of 0.50 and a thickness of 10 to 5000 Å
Ni alloy layer and S of 100-1000 mg / m ² on it
A method of providing an n-plated layer and performing a reflow treatment to provide a chromate coating layer having a chromium equivalent amount of 5 to 20 mg / m ² (JP-A-60-17099). Further, recently (3) per surface of steel sheet 150-2500 mg / m
² Ni plating layer, and S with a grain size of 0.2-4.0μ on it
A material for a welding can having a tin-plated layer in which 10 to 400 mg / m ^{2 of} n-plated particles are scattered and a chromate coating of 1 to 50 mg / m ² thereon is also disclosed.

First, the Ni-plated / chromated steel sheet (1) is used as a TFS-type welding can material that does not use tin.
It has a sufficiently good weldability for practical use, and due to its excellent heat resistance, paint adhesion and corrosion resistance after coating, it has been put to practical use in large quantities. The thin tin-plated material (hereinafter referred to as “LTS”) having the Ni-based undercoating of (2) is a soft, low-melting metal tin (hereinafter referred to as “LTS”) that is soft and has a low melting point after baking for the purpose of further improving weldability. "Free-Sn") and corrosion resistance can be ensured by a Ni-based undercoating, 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 according to the intended use such as contents. The granular Sn / Ni plated steel sheet of (3) has good weldability, heat resistance,
It has paint adhesion, but has not yet been put to practical use.

[0004]

In recent years, in combination with the further improvement of the can manufacturing technology and the cost reduction of the can, in recent years, the raw material of the original plate has been made thinner, and the baking of paint at a high temperature and a short time and the speed of seam welding have been accelerated. Is strongly requested. That is, the thinning of the original plate material is from the current plate thickness of 0.20 to 0.24 mm to 0.
A thin material of 2 mm or less is required, and in the high temperature short time baking, the current paint baking conditions are 200 to 210 ° C x 10 m.
There is a strong demand for high-temperature short-time baking, in which the temperature is raised from in to a temperature not lower than the melting point of tin (232 ° C.) in several tens of seconds and the paint is baked during that time. The speedup of seam welding is 40-60m /
70 ~ 100m / mim from min wire speed
That speed is planned. 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.

First, the Ni-plated / chromate-treated steel sheet has a problem that the proper welding range for obtaining sufficient welding strength and good welding appearance becomes extremely narrow as the sheet thickness becomes thinner. This is because the molten metal jumps out (hereinafter referred to as "scatter") before the welding current increases and sufficient welding strength is obtained.
This is a problem that corrosion resistance and welding strength deteriorate after coating. Ni plating /
Chromate-treated steel sheet can sufficiently support its good heat resistance, and can secure good corrosion resistance after painting. On the other hand, in the case of LTS type materials, deterioration of weldability due to thinning can be avoided by controlling the tin plating amount on the inner and outer surfaces of the can, but when baking at high temperature for a short time, the baking temperature of the paint is the melting point of tin. Therefore, there is a problem that the tin in the surface layer is melted and the corrosion resistance after coating is significantly deteriorated.

Further, in the case of granular Sn / Ni plated steel sheet, good weldability can be secured at the conventional welding speed,
As the welding speed increases, the proper welding range becomes narrower and it is not possible to cope with the speeding up of seam welding. To solve these problems, the present invention has a sufficiently wide proper welding range when performing high-speed short-time baking and high-speed seam welding, and for a welding can that exhibits good paint adhesion and post-paint corrosion resistance. It is intended to provide materials. In particular, the present invention exerts a very remarkable effect in ensuring good weldability when a thin material is used as the plating original plate.

[0007]

DISCLOSURE OF THE INVENTION As a result of investigations by the present inventors on an appropriate surface coating composition of materials for welding cans, a wide appropriate welding range in which no scattering occurs even at high speed welding and sufficient welding strength can be obtained. It was found that the contact resistance at the weld pole / material interface and the material / material interface is reduced as much as possible in order to secure the above. The residual amount of free-Sn after baking is most effective for reducing the contact resistance, but if free-Sn is present on the entire surface of the material, the tin plating layer is inferior in heat resistance, so baking is performed at high temperature for a short time. In that case, free-Sn melts, and it is difficult to secure good corrosion resistance after coating. Solve these problems,
It has been found that the following means are most effective in achieving both practical performance as a material for a welding can.

That is, in order to reduce the contact resistance without causing significant deterioration of the corrosion resistance after coating due to complete melting of the tin plating layer by baking at high temperature for a short time, it is important to intersperse the tin plating layer in a granular form. It turned out to be effective. At this time, in order to exhibit excellent weldability during high-speed welding,
It is important to increase the plating amount and particle size of the granular Sn and strictly control it, compared with the conventional coating structure. Further, it was found that by providing a Ni plating layer having good heat resistance under the granular Sn plating layer, it is possible to sufficiently withstand high temperature short time baking and to secure good paint adhesion and post-coating corrosion resistance. That is, in order to secure good weldability and good heat resistance that can withstand high temperature short time baking, the point is to provide a granular tin plating layer on the Ni plating layer on the steel plate surface.

Further, in order to secure good paint adhesion and corrosion resistance after coating, a chromate film layer must be provided on the granular Sn plating layer, but the hydrated chromium oxide layer is an insulator and exists in a trace amount. Since chromium metal has a high melting point, the chromate coating has a negative effect on weldability. Therefore, the chromate coating must be regulated to the minimum amount necessary to ensure good paint adhesion and corrosion resistance after painting. As a result of a detailed study based on these ideas, the present inventors found that a material for a welding can having excellent weldability as a material for a welding can that can be baked at high temperature for a short time with a thin material, paint adhesion, and corrosion resistance after painting It was found that it can be obtained.

The present invention was made on the basis of the findings, and the gist of the invention is 150 to 250 per surface of the steel sheet.
It has a Ni plating layer of 0 mg / m ² and further has 400 to 250 Sn plating particles with a particle size of 0.2 to 12.0 μm.
Welding can material excellent in high-speed seam weldability, heat resistance, and paint adhesion in which a Sn plating layer scattered at 0 mg / m ² and a chromate film of 1 to 50 mg / m ^{2 in} terms of chromium are further formed on it. To provide.

[0011]

The present invention will be described in detail below. In the present invention, the original plating plate is not particularly limited, and a steel plate that is usually used as a container material is used. There is no particular restriction on the manufacturing method, material, etc. of the plated original plate, and it is manufactured through the steps of ordinary steel billet manufacturing such as hot rolling, pickling, cold rolling, annealing and tempering. Furthermore, this plated original plate is cold-rolled and then annealed according to the required can strength and plate thickness, and then re-cold-rolled (that is, 2C).
R method). First, the coating composition that exhibits good heat resistance and paint adhesion will be described.
As mentioned above, the heat resistance is the baking of the paint in a high temperature and a short time, which raises the temperature above the melting point of tin in a few tens of seconds, and it is necessary to withstand this baking condition and secure good corrosion resistance after painting. , At least a metal having a melting point higher than that of tin must be plated. Further, not only heat resistance, but also good corrosion resistance, paint adhesion, and properties that do not impair the good weldability secured by the granular tin plating layer must be provided.

As a result of various studies conducted by the present inventors, N
It has been found that these problems can be solved by applying the i-plated layer. That is, 145 of Ni metal
It has been found that by effectively utilizing the high melting point of 0 ° C., good heat resistance capable of withstanding high temperature short time baking can be exhibited, and good post-coating corrosion resistance and weldability can be secured.
In particular, regarding the weldability, it was found that the good weldability obtained by the upper layer of granular tin is not impaired, and the weldability is excellent due to the excellent forge weldability of Ni metal. Forge weldability is a characteristic that not only the metal is completely melted at the time of welding to exert a strong welding strength, but also the strong bonding strength is obtained by thermocompression bonding at a high temperature without completely melting the metal.
The i metal is a metal having particularly good forgeability.

The Ni plating layer is also important from the viewpoint of ensuring good corrosion resistance. Although Ni metal itself exhibits extremely good corrosion resistance, when Ni plating is applied to the steel plate, a local battery of Fe and Ni is formed in the pinhole part of the plating layer, and Fe is dissolved, so pitting corrosion occurs in the steel plate. To do.
That is, the point is to reduce the pinholes in the Ni plating layer in order to ensure good corrosion resistance. Further, regarding the paint adhesion, good adhesion can be ensured in the portion where the chromate film is formed on the Ni plating layer in which the granular Sn is not deposited. The reason why it is difficult to secure good paint adhesion at the granular Sn precipitation portion is that brittle tin oxide is generated during paint baking, which is destroyed by damage such as can manufacturing and causes peeling of the coating film. In the Ni-plated layer, such a brittle oxide film is not formed and good paint adhesion can be secured.

Regarding this Ni plating amount, proper plating
150 ~ 2500mg / m as quantity ² Regulated by. N
i plating amount is 150mg / m² Below the plating layer
Since there are many holes, good corrosion resistance cannot be secured.
In addition, good heat resistance cannot be ensured. Also, N
i plating amount is 2500mg / m² Of the plating layer
Corrosion resistance and heat resistance due to reduced pinholes
The improvement effect is saturated and economic demerits occur.
To do. There is no particular restriction on the method of applying Ni plating.
However, Watts bath, sulfuric acid bath, chloride bath, etc. that are usually performed
The plating bath of is appropriate.

Next, the function and effect of the coating structure which exhibits good weldability will be described. Weldability does not occur,
The wider the proper welding range where sufficient welding strength can be obtained, the better the weldability is evaluated. The most effective way to improve seam weldability is to reduce the contact resistance at the electrode / material surface and at the material / material interface. The reason for this is that if the contact resistance at the electrode / material and material / material interface is high, the current concentrates during welding, causing localized heat generation and scattering. In other words, if the welding current is increased in order to secure the welding strength, scattering occurs at the location where local heat is generated before sufficient welding strength is obtained, so there is no proper welding range and weldability Is rated as bad. In contrast,
In the case of materials with low contact resistance at the electrode / material and material / material interface, local heat generation due to current concentration is less likely to occur, and sufficient welding strength can be obtained without scattering, resulting in good weldability. Is evaluated.

Such a tendency of the seam weldability becomes remarkable particularly in high-speed welding in which the welding speed is increased. In other words, 40-60m / min at the conventional wire speed
With such welding speed, there is a proper welding range even if the contact resistance is not so low. However, 70-100m
As the welding speed increases with the / min, the amount of welding heat input per unit time increases and "scattering" easily occurs, and the appropriate welding range becomes narrow. In order to have a wide welding range even during high-speed welding, it is necessary to further reduce the contact resistance. In order to reduce the contact resistance at the electrode / material and the material / material interface as described above, it is not sufficient to use the coating structure of Ni plating followed by chromate treatment, which is a heretofore known technique. It has been found that applying a tin-plated layer in a granular form is very effective in reducing the contact resistance. That is, as a coating composition capable of exhibiting good weldability, a coating composition in which the surface of the steel sheet is first plated with Ni, the tin is then plated with granular tin, and the chromate coating is further provided is suitable.

The reason why the contact resistance can be reduced and good weldability can be secured by providing the granular tin plating layer on the Ni plating layer is considered as follows. (1) Since the soft tin metal is present in the lower layer of the Ni plating layer, the contact area between the pole wheel / material and the material / material is widened by the pressure applied from the pole wheel during welding, and the contact resistance is greatly increased. It can be reduced. (2) Since tin metal has a low melting point, it is easily melted by the heat generated during welding, which has the great effect of widening the contact area between the pole wheel / material and material / material, and the contact resistance decreases, so the local area during welding. Current concentration can be prevented.

In order to obtain the above-mentioned effects with a small amount of tin plating, it is difficult for the tin plating layer to be an ordinary smooth plating layer, and it is important to make the tin plating layer granular. This is because the smooth tin-plated layer is alloyed entirely during baking at high temperature and for a short time, so that it has a soft low melting point fre.
The e-Sn does not remain and the contact resistance reduction effect cannot be exhibited. Since the alloying of the tin plating layer proceeds in the height direction at the interface between the steel plate and the tin plating layer, if the granular tin plating layer is used, the amount of residual free-Sn that exhibits good weldability even after high temperature and short time baking is exhibited. Can be secured.

Therefore, in order to obtain good weldability, a granular tin plating layer is applied, but the plating amount is 400 to 280.
It is regulated to 0 mg / m ² . This is because when the amount of granular tin plating is less than 400 mg / m ² , alloying proceeds during high-temperature short-time baking, and it is not possible to secure a sufficient amount of free-Sn residue, which is especially good for high-speed welding with a large heat input per unit time. I can't exert my ability. Further, when the amount of granular tin plating exceeds 2800 mg / m ² , the free-Sn residual effect is saturated and a large amount of low-melting free-Sn remains. Therefore, even if a Ni plating layer is provided on the upper layer as described later. When high temperature baking that reaches a temperature exceeding the melting point of tin is performed, tin metal is melted and corrosion resistance is significantly deteriorated. That is, it becomes impossible to secure heat resistance that can withstand high temperature baking.

Further, the size of the granular tin plating is 0.2
It is regulated to ~ 12.0μ. This is because if the grain size is less than 0.2 μm, free-Sn does not remain due to the progress of alloying in the height direction due to baking at high temperature for a short time, and good weldability cannot be ensured. The particle size is 12.0
If it exceeds μ, the effect of improving the weldability is saturated, the economic merit is lost, and the heat resistance deteriorates. Therefore, high temperature baking melts the tin metal and deteriorates the corrosion resistance after coating. As described above, the proper and economical plating amount and particle size of the granular tin plating layer capable of achieving both good weldability and heat resistance are 400 to 2800 mg / m ² and 0.2 to 12.0.
is μ. The method of applying the granular tin plating layer on the steel sheet is not particularly limited, but the following method is preferable. If tin plating is performed at a low current density in a dilute acidic aqueous solution of Sn ²⁻ ions, a granular tin plating layer can be formed on the steel sheet. For example, tin plating is preferably performed at a current density of 0.1 to 30 A / dm ² in an acidic solution having an Sn ²⁺ ion amount of 1 to 400 g / l.

Further, a chromate treatment is applied in order to improve the plated steel sheet having such a coating layer, paint adhesion and coating corrosion resistance. The chromate coating prevents undercutting corrosion on the inner surface of the can, in which the contents of the can pass through the coating film to cause corrosion under the coating film, and on the outer surface of the can, the so-called filamentous rust that occurs under the coating film during storage. It is very effective in improving rust resistance such as filiform corrosion. By forming such a chromate coating, the adhesion of the coating does not deteriorate over a long period of time, and good corrosion resistance,
The rust resistance is retained. Further, the chromate film has a great effect of preventing the blackening of the surface of the steel sheet, that is, the sulfurization blackening, which is observed in the case of foods containing sulfur compounds, such as fish meat and livestock products. As described above, the chromate coating has a great effect on the performance improvement when it is used after being coated, but it is a negative factor on the weldability. The chromate film mentioned here refers to two cases: a single film of hydrated chromium oxide, that is, the original chromate film, and another film consisting of a lower layer of metal chromium layer and an upper layer of hydrated chromium oxide layer. pointing. Since the hydrated chromium oxide film is an electrical insulator, 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, a good coating performance and a proper amount of chromium deposition which does not deteriorate the weldability in practical use are very important. In the present invention, the amount of chromium deposited is selected to be 1 to 50 mg / m ² per one surface in terms of metallic chromium. That is,
When the amount of deposited chromium is less than 1 mg / m ² , the effect of improving paint adhesion and preventing undercoat corrosion such as undercutting corrosion cannot be obtained. Therefore, the amount of deposited chromium of 1 mg / m ² or more is desirable. On the other hand, when it exceeds 50 mg / m ² , the contact resistance is remarkably increased, and dispersion due to local heat generation is likely to occur to deteriorate weldability. Therefore, the chromium deposition amount is regulated to 50 mg / m ² or less.

The chromate treatment may be carried out by any method such as dipping treatment with an aqueous solution of various sodium salts, potassium salts and ammonium salts of chromic acid, spray treatment, electric field treatment and the like, and cathodic electric field treatment is particularly excellent. In particular, cathodic electric field treatment in an aqueous solution obtained by adding SO ₄ ^2- ions, F ⁻ ions (including complex ions) or a mixture thereof to chromic acid is the most excellent. The concentration of chromic acid is not particularly limited, but a range of 20 to 200 g / l is sufficient. The amount of anion added is 1/300 to 1 / of Cr ⁶⁺
The best chromate film is obtained at 25 / preferably 1/200 to 1/50. Anion amount is 1/3 of Cr ⁶⁺
When it is less than 00, a high-quality chromate film which is homogeneous and uniform and which greatly affects the coating performance cannot be obtained. On the other hand, when it is 1/25 or more, the amount of anions taken 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 compounds of sulfuric acid, chromium sulfate, ammonium fluoride, sodium fluoride and the like.

The bath temperature is not particularly limited, but is 30
The range of 70 ° C is an appropriate temperature range from the viewpoint of workability. A cathode electric field current density of 5 to 100 A / dm ² is sufficient. The treatment time is 1 to 20 m when the amount of deposited chromium is the same as above, in any combination of the treatment conditions.
Set so that it falls within the range of g / m ² . The ratio of the metallic chromium layer to the hydrated chromium oxide layer in the two-layer chromate film is not particularly limited within the above range of the amount of adhesion, but is preferably in the range of 0.6 ≦ hydrated chromium oxide / metallic chromium ≦ 3. That is, when the amount of hydrated chromium oxide is smaller than that of metallic chromium, the uniform coating property of the hydrated chromium oxide layer on the metallic chromium layer is inferior, so that the coating adhesion tends to deteriorate. On the other hand, when the hydrated chromium oxide layer is more than the metallic chromium layer,
Anions and Cr ⁶⁺ contained in the hydrated chromium oxide layer
It is not preferable because the amount of ions increases and these ions elute when exposed to a high temperature environment after coating, and micro swelling (so-called blisters) easily occurs under the coating film.
Therefore, it is preferable to set the composition ratio of hydrated chromium oxide and metallic chromium within the range of 0.6 to 3 as described above.

Examples of the present invention will be described below, and the results are shown in Tables 1 and 2. By cold rolling or double rolling after annealing, the plated original plate adjusted to a predetermined plate thickness
% Electrolytically degreasing in a caustic soda, washing with water, electrolytic pickling with 10% sulfuric acid, surface activation and surface treatment. First,
Ni plating is performed under the conditions shown in (1), then granular tin plating is performed under the conditions shown in (2), and then (3) (A)-
A chromate film was formed in the treatment bath shown in (C). (1) Ni plating conditions plating bath composition _{NiSO 4 · 6H 2 O 75g /} l NiCl 2 · 6H 2 O 140g / l H 3 BO 3 30g / l plating bath temperature 50 ° C. Current density 20A / dm ² (electrolysis time is Ni Adjust according to the plating amount)

(2) Granular tin plating treatment Plating bath composition SnSO ₄ 10-30 g / l H ₂ SO ₄ 60 g / l Plating bath temperature 60 ° C. Current density 0.1-30 A / dm ² (electrolysis time depends on Sn plating amount) Adjust the tin plating particle size according to the amount of SnSO ₄ and the current density.

(3) Chromate treatment bath (A) CrO ₃ 100 g / l SO ₄ ^2- 0.6 g / l (B) Na ₂ Cr ₂ O ₇ 24 g / l pH 4.5 (C) CrO ₃ 30 g / l ^{_{SO 4 2- 0.05g / l Na 2}} SiF 6 2.5g / l NH 4 F 0.5g / l

Regarding the above-mentioned treated materials, the following (A) to
The item (G) was implemented and its performance was evaluated. (A) Measurement of contact resistance The contact resistance value that greatly affects the seam weldability was measured using a CF-type electrode spot welder. The test pieces for measurement were subjected to baking under the condition that the temperature was raised to 310 ° C. in 20 seconds on the assumption of baking at high temperature for a short time.
The static resistance measuring method using a CF type electrode is shown below. The electrodes used were made of chrome copper and had a tip diameter of 4.5 mmφ. Two test pieces are placed between the electrodes, and a constant current of 1 A is applied between the electrodes while being pressurized to 200 kgf by an air cylinder, and the voltage between the electrodes / electrodes, between the electrodes / steel plates, and between the steel plates / steel plates at that time. The static resistance in the cold was obtained by measuring the drop with a nanovoltmeter.

(B) Seam Weldability The test piece is assumed to be coated and baked at high temperature for a 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. Welding is performed by changing the current under the conditions of a lapping margin of 0.5 mm, a pressing force of 45 kgf, and a welding wire speed of 80 m / min, and the minimum current value that provides sufficient welding strength and welding defects such as "scattering" are conspicuous. The evaluation was performed by comprehensively judging from the width of the appropriate current range consisting of the maximum current value to start and the occurrence of welding defects.

(C) Cross-cut test Epoxyphenol-based paint was applied at 55 mg / dm ² on the surface corresponding to the inner surface of the can of the test piece, and 40 mg / dm ² of clear lacquer was applied on the surface corresponding to the outer surface of the can.
Drying and curing were performed under baking conditions in which the temperature was raised to 15 ° C in 15 seconds. Subsequently, scratches were placed on each surface at 1 mm intervals, a total of 100 grids were prepared, and the tape was rapidly peeled off, and the peeled state was evaluated.

(D) UCC (Under cutting roller
Evaluation test To evaluate the corrosion resistance after painting of the surface corresponding to the inner surface of the can,
Epoxy phenol for cans (pheno
50% / dm3 on one side ² Application
And bake under the condition that the temperature is raised to 310 ° C in 18 seconds.
I went. After that, scrub to reach the iron surface of the painted plate.
And mix with 1.5% citric acid-1.5% sodium chloride mixture.
It was immersed in a certain test liquid under the atmosphere at 55 ° C. for 4 days.
After the test is completed, quickly test the scratch and flat parts.
Peeled off to prevent corrosion under the coating film near the scratches.
Litting pitting status and flat surface coating peeling
The situation was judged and evaluated comprehensively.

(E) Sulfuration blackening resistance test The same coating as (E) was applied to the surface corresponding to the inner surface of the can, and 1
The t-bent test piece was put into a homogenized commercial mackerel boiled product and subjected to retort treatment at 115 ° C. for 90 minutes. After the test, the sulfide blackening state of the bent portion and the flat portion was evaluated. (F) Philiform Corrosion Test In order to evaluate the thread-like rust resistance of the surface corresponding to the outer surface of the can, 40 mg / dm ^{2 of} clear lacquer was applied and dried and hardened under the baking conditions of heating up to 280 ° C. for 17 seconds.
Next, insert a scratch that reaches the iron surface with a knife, and 3
A 5% salt water spray was applied at 5 ° C. for 1 hour, followed by rapid washing with water, drying, and then leaving at 25 ° C. and 85% relative humidity for 2 weeks to evaluate the filamentous rust property.

(C) Actual Can Test Epoxy phenol-based material on the surface of the test piece corresponding to the inner surface of the can.
55 mg / dm of paint ² Apply and then correspond to the outer surface of the can
40 mg / dm of clear lacquer on the surface² After applying
Dry under baking conditions that heat up to 320 ° C in 22 seconds
Cured. Continue to control the can body using a seam welder.
Made welded part is repaired with epoxy resin and orange
After filling the juice and cola, wrap and squeeze the # 25 tin can lid.
Therefore, it was stored at 38 ° C. for 12 months. After the test,
The amount of iron taken out and the inner surface of the can (flat part and welded part)
The corrosion state was observed and evaluated.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

As can be seen from the results summarized in the table, the materials for welding cans within the range defined by the present invention are more effective than the comparative materials such as Ni plating amount and Sn plating particles which deviate from the scope of the present invention. It exhibits stable and excellent properties such as weldability and corrosion resistance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshinori Katayama 1-1 Tobahata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka New Nippon Steel Corporation Yawata Works

Claims (1)

[Claims] 1. 150 to 250 per surface of a steel plate
It has a Ni plating layer of 0 mg / m ² and a grain size of 0.
2-12.0μ Sn plated particles 400-2800m
Excellent in high-speed seam weldability, heat resistance, and paint adhesion, characterized by a Sn plating layer scattered at g / m ² and a chromate film of 1 to 50 mg / m ^{2 in} terms of chromium formed on it Material for welded cans.