JPH0665789A - Material for welded can excellent in high-speed seam weldability, resistance to corrosion and heat and coating adhesion - Google Patents

Abstract

PURPOSE:To produce a material for the welded can excellent in high-speed seam weldability, resistances to corrosion and heat and coating adhesion by successively forming an Ni-Fe alloy plating layer, an Sn plating layer and a chromate coating film on the surface of a steel sheet under specified conditions. CONSTITUTION:An Ni-Fe alloy plating layer (contg. about 10-80wt.% Fe) or an Ni-P alloy plating layer (contg. about 0.1-10wt.% P) is formed on the surface of a steel sheet at 150-2500mg/m<2> per side. An Sn plating layer, in which the Sn plating grains having 0.2-12.0mum diameter are interspersed at 400-2800mg/m<2>, is formed on the plating layer, and further, a chromate coating film is formed on the Sn plating layer at 1-50mg/m<2> expressed in terms of chromium. When the coated material is baked at high temp. for a short time and then high-speed seam welded, a material for the welded can having a sufficiently wide appropriate welding range and excellent in coating adhesion and corrosion resistance after coating is obtained.

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 structure excellent in high-speed seam weldability, heat resistance, corrosion resistance and paint adhesion.

[0002]

2. Description of the Related Art In recent years, the system represented by the pseudoronic method is used.
Practical application of the dome welding can manufacturing method is progressing rapidly. This melt
In order to cope with the expansion of the canning method, it is used as a material for welding cans.
Various materials have been developed and put into practical use. Ever developed
The following can be mentioned as the welded can material. (1) 150 to 2500 mg / m per surface of steel plate
²Ni plating layer and 2 to 15 mg / m in terms of chromium²Ku
Welding can material formed of a chromate coating layer
No. 56-169788) (2) Ni / Ni + Fe = 0.02 on a steel plate by weight ratio
Fe-with a composition in the range of 0.50 and a thickness of 10 to 5000 Å
Ni alloy layer and 100-1000 mg / m on it ²Of S
An n-plated layer is provided and reflow processing is performed to convert it to chromium.
5 to 20 mg / m²Method for providing the chromate film layer
(JP-A-60-17099) Furthermore, recently, (3) 150 to 2500 mg / m on each side of the steel plate surface.
²Ni-Fe alloy or Ni-P alloy plating layer
And Sn-plated particles with a particle size of 0.2-4.0μ on it.
10-400 mg / m²Tin-plated layer scattered, and further
1-50mg / m on top²Welding with chromate coating
Materials for cans are also open to the public.

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-Fe or granular Sn / Ni-P plated steel sheet of (3) has good weldability, corrosion resistance, heat resistance and paint adhesion, but has not yet been put to practical use.

[0004]

In recent years, further progress in can-making technology and cost reduction in can-making, in combination with the further reduction in can-making cost, enables thinning of the original plate material and high-speed coating baking and seam welding at high temperature and in a short time. 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 20 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
There is a strong demand for high-temperature short-time baking in which the temperature is raised from min to a temperature above the melting point of tin (232 ° C.) in several tens of seconds, and the paint is baked during that time. The speed of seam welding can be increased to 40 to 60 m by considering the hardware of the welding machine.
70-100m / mi from wire speed of / min
A speedup of n 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-Fe or granular Sn / Ni-P plated steel sheet, good weldability can be secured at the conventional welding speed, but as the welding speed increases, the proper welding range becomes narrower and the seam It cannot fully cope with the speeding up of 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 when free-Sn is present on the entire surface of the material, the tin plating layer is inferior in heat resistance, so baking at high temperature for a short time is required. When it is performed, free-Sn melts, and it is difficult to secure good corrosion resistance after coating.

It has been found that the following means are 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 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, the tin plating layer is interspersed in a granular form with a great effect. I knew that. At this time, in order to exhibit excellent weldability even in 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, a Ni-Fe alloy layer or N having excellent heat resistance and corrosion resistance is formed below the granular Sn plating layer.
It has been found that by providing the i-P alloy plating layer, it is possible to sufficiently withstand high temperature short time baking and to secure good paint adhesion and corrosion resistance after coating. That is, in order to secure good weldability and corrosion resistance and good heat resistance capable of withstanding short-time high temperature baking, a Ni-Fe alloy layer or a Ni-P alloy plating layer is formed on the surface of the steel sheet, and then granular tin plating is applied thereon. The point is to provide layers.

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 film 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 thereof is a Ni-Fe alloy layer of 150 to 2500 mg / m ² per surface of a steel plate,
Alternatively, it has a Ni-P alloy plated layer, on which Sn plated particles having a particle size of 0.2 to 12.0 [mu] are 400 to 280.
Welding can with excellent high-speed seam weldability, corrosion resistance, heat resistance, and paint adhesion, with 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 formed on the Sn plating layer. The purpose is to provide materials.

[0010]

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 ordinary steel slab manufacturing processes such as hot rolling, pickling, cold rolling, annealing and tempering. Further, 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, 2CR).
Method). First, the coating composition that exhibits good heat resistance, corrosion resistance, and paint adhesion will be described. The heat resistance required as described above is baking of the paint in a high temperature in a short time at a temperature that rises above the melting point of tin in a few tens of seconds, and in order to withstand this baking condition and secure good post-paint corrosion resistance. , 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 investigations conducted by the present inventors, N
It has been found that these problems can be solved by applying an i-Fe alloy metal or Ni-P alloy plating layer. That is, it was found that by effectively utilizing the high melting point of the Ni-Fe alloy or the Ni-P alloy, good heat resistance capable of withstanding high temperature short time baking can be exhibited, and good post-painting corrosion resistance and weldability can be secured. It was In particular, regarding the weldability, the good weldability obtained by the upper layer granular tin is not impaired, and the Ni-Fe alloy or Ni-
It has been found that the P alloy plating layer exhibits excellent weldability due to the excellent forgeability. Forge weldability is a characteristic that not only the metal completely melts at the time of welding to exert a strong welding strength, but also strong bonding strength can be obtained by thermocompression bonding at high temperature without completely melting the metal. Layer or N
The i-P alloy plating layer is a metal having excellent forgeability.

Further, a Ni-Fe alloy layer or Ni-P
The alloy 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. However, Ni-Fe
In the case of alloy or Ni-P alloy plated layer, the potential is N
Since it is more basic than i metal, even if there are pinholes in the alloy layer, there is little occurrence of pitting corrosion in the steel sheet by forming a local battery between the base metal and the plating layer. That is, N
The i-Fe alloy or Ni-P alloy plated layer is more N
Corrosion resistance is improved as compared with the i-plated layer.

Further, regarding the paint adhesion, good adhesion can be ensured in the portion where the chromate film is formed on the Ni-Fe alloy layer or the Ni-P alloy 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-Fe alloy layer or the Ni-P alloy plated layer, such a brittle oxide film is not formed and good paint adhesion can be secured. The Ni-Fe alloy layer or Ni-P alloy plating amount is 150 to 2500 m as an appropriate plating amount.
regulated to g / m ² . Ni-Fe alloy layer or Ni
The -P alloy plating amount is less than 150 mg / m ^2, can not be pinholes in the plating layer to secure many good corrosion resistance, also can not be ensured good heat resistance. Further, when the plating amount exceeds 2500 mg / m ² , the effect of improving the corrosion resistance and heat resistance due to the reduction of pinholes in the plating layer is saturated, and an economic disadvantage occurs.

The alloy composition is not particularly limited, but the following range is a preferable range. Ni-Fe
In the alloy layer, Fe% in the alloy layer is preferably 10 to 80% by weight. When Fe% is less than 10%, there is a possibility of pitting corrosion from the pinhole portion because the potential is not different from that of the Ni plating layer. On the other hand, when the Fe% exceeds 80%, the effect of the Ni metal is lost and the corrosion resistance tends to deteriorate. Therefore, Ni-
The Fe% of the Fe alloy layer is preferably 10 to 80%. Furthermore,
As for the Ni-P alloy layer, P% is 0.1 to 1 by weight.
0% is preferable. If P% is less than 0.1%, the effect of P is lost and the potential is no different from that of the Ni plating layer, and pitting corrosion from the pinhole portion is feared. On the other hand, P% is 10
If it exceeds%, the alloy layer becomes hard and cracks are likely to occur during the can-making process, and the corrosion resistance tends to deteriorate. Therefore, P% in the Ni-P alloy plated layer is 0.1
10% is preferable.

The method for applying the Ni-Fe alloy layer is not particularly limited, but the following method is suitable. (1) A method of alloy plating which is usually carried out from a sulfuric acid bath, a chloride bath or the like. (2) An Ni plating layer is formed from a Watts bath, a sulfuric acid bath, a chloride bath, etc., and the Ni metal is diffused into the base iron by heat treatment to form N.
A method of forming an i-Fe alloy layer. (3) A method in which the Ni—Fe alloy plated layer obtained in (1) is further heat-treated to obtain a diffusion layer. The methods (2) and (3) can exhibit more economical advantages if the diffusion step and the refining step are combined. Ni-P is not particularly limited, and the following method is suitable. (1) A method of electrolytically plating a Ni-P alloy from a sulfuric acid bath, a chloride bath or the like. (2) A method in which sodium hypophosphite is added to a sulfuric acid bath, a chloride bath or the like and electroless Ni-P alloy plating is performed.

Next, the function and effect of the coating structure that exhibits good weldability will be described. Weldability does not occur,
The wider the suitable welding range with which 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 interface and 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 seam weldability becomes remarkable especially 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. Thus, in order to reduce the contact resistance at the electrode / material and the material / material interface, the coating structure of performing the chromate treatment after Ni plating, which is a known technique, is not sufficient, and tin on the upper layer of the Ni plating layer is not sufficient. It has been found that applying the plating layer in a granular form is very effective in reducing the contact resistance. That is, as a coating structure capable of exhibiting good weldability, first the Ni-F is applied to the steel plate surface.
e alloy layer or Ni-P alloy plating layer plating,
A suitable coating structure is that granular tin plating is applied on top of this and a chromate coating is further provided.

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-Fe or Ni-P alloy 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 welding resistance is reduced, 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,
A granular tin plating layer is applied to obtain good weldability, but the plating amount is regulated to 400 to 2800 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,
Since a sufficient residual amount of e-Sn cannot be secured, good weldability cannot be exhibited especially during high-speed welding with a large heat input per unit time.

The amount of granular tin plating is 2800 mg / m
^When it exceeds ² , the free-Sn residual effect is saturated, and too much free-Sn with a low melting point remains, so
As will be described later, even if a Ni plating layer is provided as an upper layer, when high temperature baking reaching 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 regulated to 0.2-12.0 μ of grain size. This is because if the grain size is less than 0.2 μm, free-heating occurs due to the progress of alloying in the height direction due to high temperature short time baking.
Sn does not remain and good weldability cannot be secured. If the particle size exceeds 12.0μ, the effect of improving the weldability is saturated, the economic merit is lost, and the heat resistance deteriorates. Therefore, the high temperature baking melts the tin metal and deteriorates the corrosion resistance after coating. . In this way, 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 0.2-12.0μ. 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 with 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, the amount of Sn ²⁺ ions is 0.1 to 30 A / dm in an acidic solution of 1 to 400 g / l.
It is preferable to perform tin plating at a current density of ² .

Further, the plated steel sheet having such a coating layer is subjected to a chromate treatment in order to improve 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 film,
Adhesion of the coating 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 great effect of preventing the blackening of the surface of the steel sheet, that is, the sulfurization blackening, which is seen in the case of foods containing a sulfur compound, for example, fish 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. Chromate treatment is immersion treatment with an aqueous solution of various chromic acid sodium salts, potassium salts, and ammonium salts, spray treatment,
It may be performed by any method such as electrolytic treatment, but cathodic electrolytic treatment is particularly excellent. In particular, SO ₄ ^2-
Cathodic electrolysis in an aqueous solution containing added ions, F ⁻ ions (including complex ions) or a mixture thereof is the best. Although the concentration of chromic acid is not particularly limited, it is 20 to 2
A range of 00 g / l is sufficient.

The amount of anion added is 1/30 of Cr ⁶⁺
The best chromate film is obtained at 0 to 1/25, preferably 1/200 to 1/50. The amount of anion is Cr ⁶⁺
If the ratio is 1/300 or less, a high-quality chromate film that is homogeneous and uniform and that greatly affects the coating performance cannot be obtained. Also, 1
When the ratio is / 25 or more, the amount of anions incorporated in the resulting chromate coating increases, and the coating performance, particularly 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 a range of 30 to 70 ° C. is an appropriate temperature range from the viewpoint of workability. Cathode electrolysis current density is 5-100A / dm
A range of ² is sufficient. The treatment time is set such that the chromium deposition amount falls within the range of 1 to 50 mg / m ² shown above under any combination of the treatment conditions.

The ratio of the metal chromium layer to the hydrated chromium oxide layer in the two-layer chromate film is not particularly restricted within the above-mentioned range of the adhesion amount, but the range of 0.6≤hydrated chromium oxide / metal chromium≤3 is preferable. . 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 amount of hydrated chromium oxide layer is larger than that of the metallic chromium layer, the amount of anions and Cr ⁶⁺ ions contained in the hydrated chromium oxide layer increases, and these ions are eluted when exposed to a high temperature environment after coating. Occurs, and minute swelling (so-called blisters) easily occurs under the coating film, which is not preferable. 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 Table 1. By cold rolling or double rolling after refining, the plated original plate adjusted to a predetermined plate thickness is electrolytically degreased in 5% caustic soda, washed with water, then electrolytically pickled in 10% sulfuric acid, and surface-treated after surface activation. went. First, (1)-
A Ni-Fe alloy layer or a Ni-P alloy plating layer was formed under the conditions shown in (A) to (D). At this time, Ni-F
When forming the e-diffusion alloy layer, a cold-rolled material was used for both the diffusion treatment step and the refining treatment step. Next, granular tin plating is applied under the conditions shown in (2), followed by (3)-(A).
What produced | generated the chromate film in the processing bath shown to-(C) was created.

[0026] (1) Ni-Fe alloy layer or the Ni-P alloy plating conditions (A) Ni-Fe alloy plating Plating bath composition _{NiSO 4 · 6H 2 O 75g /} l NiCl 2 · 6H 2 O 140g / l FeSO 4 · 7H ₂ O 30 to 150 g / l (Adjusted according to alloy composition) H ₃ BO ₃ 30 g / l Plating bath temperature 50 ° C. Current density 20 A / dm ² (Electrolysis time is adjusted according to plating amount)

[0027] (B) Ni-Fe diffusion alloy layer Ni plating conditions plating bath composition _{NiSO 4 · 6H 2 O 70g /} l NiCl 2 · 6H 2 O 160g / l H 3 BO 3 30g / l plating bath temperature 50 ° C. Current density 20 A / dm ² (electrolysis time is adjusted according to the plating amount) Heat treatment A heat treatment was performed at a temperature of 500 ° C. to 800 ° C. for 10 to 40 seconds depending on the degree of diffusion.

[0028] (C) Ni-P alloy plating (electrolytic treatment) plating bath composition _{NiSO 4 · 6H 2 O 60g /} l NiCl 2 · 6H 2 O 120g / l phosphorous acid 20 to 100 g / l (adjusted depending on the alloy composition ) H ₃ BO ₃ 30 g / l Plating bath temperature Normal temperature to 70 ° C. Current density 20 A / dm ² (electrolysis time is adjusted according to plating amount)

[0029] (D) Ni-P alloy plating (electroless process) plating bath composition _{NiSO 4 · 6H 2 O 60g /} l NiCl 2 · 6H 2 O 120g / l sodium hypophosphite 20 to 100 g / l (alloy composition H ₃ BO ₃ 30 g / l Plating bath temperature Normal temperature to 80 ° C. Immersion time 5 to 60 seconds (immersion time is adjusted 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 80 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 material, 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 was designed to be 32 pieces on the assumption that the coating will be continued 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. 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 The surface of the test piece corresponding to the inner surface of the can was coated with 55 mg / dm ² of epoxyphenol-based paint, and the surface of the outer surface of the can was coated with 40 mg / dm ² of clear lacquer, and 290
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 ²Application
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 add 1.5% citric acid to 1.5% salt.
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.

(G) 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 ²Disperse and further correspond to the outer surface of the can
40 mg / dm of clear lacquer on the surface²After applying
Dry under baking conditions that heat up to 320 ° C in 22 seconds
Cured. Then, using a seam welder,
Welded parts are repaired with epoxy resin and orange
# 25 tin can lid after squeezing the base and cola
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. The present invention is limited as shown in the table showing these results.
Welding can materials in the range of N are outside the scope of the present invention.
i-based alloy plating amount, Sn plating particle size and its plating amount
Compared to other comparison materials, weldability, corrosion resistance after painting, etc.
The characteristics required for materials are stably obtained.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

As described above, according to the present invention, a material for a welding can having excellent high speed seam weldability, corrosion resistance, heat resistance and paint adhesion can be obtained.

Front page continuation (72) Inventor Toshinori Katayama 1-1 Tobahata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka New Nippon Steel Co., Ltd. Yawata Works

Claims (1)

[Claims] 1. 150 to 250 per surface of a steel plate
0 mg / m ² Ni-Fe alloy plating layer or Ni-
It has a P alloy plating layer and a grain size of 0.2 to 12.0 on it.
Sn plating layer in which μ of Sn plating particles are scattered at 400/2800 mg / m ² and further 1 to 5 in terms of chromium on it
A material for a welding can having a high-speed seam weldability, corrosion resistance, heat resistance, and paint adhesion, which is characterized by having a 0 mg / m ² chromate film formed.