JPH0971876A - Steel sheet for welded can excellent in weldability, corrosion resistance, appearance and adhesion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a steel sheet for a welded can excellent in adhesion for coatig materials, appearance, corrosion resistance and adhesion for films by forming a hydroxide layer on the space between an Fe-Ni alloy plating layer formed on the surface of a steel sheet and an insular Sn plating layer. SOLUTION: The surface of a steel sheet is applied with an Fe Ni alloy plating contg. 5 to 55% Ni per face by 50 to 800mg/m<2> coating weight. On the surface of the above substrate plating, an Fe or Ni base hydroxide layer is formed so as to regulate the area coating rate of the part having 1nm to 500nm film thickness to >=50%. Next, an insular Sn plating layer formed by hot dip tinning treatment and having 40 to 98% area coating rate is formed by 400 to 2500mg/m<2> coating weight. In this steel sheet for a welded can, the roll of the hydroxide layer is mainly the securance of its weldability. When the above hydroxide layer is present, even in the case the temp. is less than the m.p. of Sn metal or above that, its alloying with the base metal can be suppressed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a can-making material,
In particular, the present invention relates to a steel plate for a welding can having excellent seam weldability, corrosion resistance, appearance and adhesion.

[0002]

2. Description of the Related Art In recent years, the technology for producing welded cans by the wire seam resistance welding method has made rapid progress, and its practical application in the field of beverage cans has made rapid progress. As a steel plate for a can used for this kind of welded can, a metal S having a large number of protrusions on the surface as disclosed in JP-A-60-208494 is used.
A surface-treated steel sheet having n and having an appropriate chromate coating layer formed thereon, or a surface-treated steel sheet for can making which is excellent in seam weldability as disclosed in JP-A-60-29484. Proposed. Using these surface-treated steel sheets for containers, paint baking is performed on the inner surface of the can to ensure corrosion resistance, and multicolor printing is performed on the outer surface of the can.

Normally, in these coating and printing processes, baking is carried out at a temperature below the melting point of Sn (about 190 to 220 ° C.) for several tens of minutes. After that, canning is performed by the wire seam welding method.
It has been conventionally known that it depends on the amount of free Sn (non-alloyed metal Sn) after printing. In general,
In the Sn-plated steel sheet, when the Sn plating amount is small, Sn is alloyed with the base metal by coating and printing, and the free Sn tends to decrease and the weldability tends to deteriorate.
Suppresses Sn alloying during painting and printing, and provides a certain amount of free S
Weldability is secured by securing n. Therefore, the above invention certainly provides a surface-treated steel plate for a welding can.

[0004]

In recent years, technological innovation has been carried out with the aim of significantly improving the can-making productivity in combination with the further improvement of the can-making technology and the cost reduction of the can-making. .
That is, it is the development of a short-time high-speed coating baking technique by high-temperature baking that exceeds the melting point of Sn, which has not been performed conventionally. With this technology, it is possible to perform painting and printing, which took several tens of minutes in the past, in tens of seconds to minutes, and it is possible to dramatically improve can-making productivity. When the above-mentioned invention is applied to this high-temperature, short-time, high-speed coating baking technique, in high-temperature baking that exceeds the melting point of Sn,
The effect of suppressing Sn alloying does not function sufficiently, the amount of free Sn decreases, and good weldability cannot be secured. Also, in the conventional invention, if the amount of Sn is increased, the amount of free Sn remaining after baking is increased, but the increase of expensive Sn is economically disadvantageous.

Further, in recent years, a laminated welded can in which an organic film is laminated on the inner surface of the can and / or the outer surface of the can instead of painting or printing tends to be put into practical use. When a Sn-based material is used as the material for the laminated welding can, poor film adhesion occurs near the weld. This is because the vicinity of the weld where the temperature rises above the Sn melting point by welding is
The n-plated layer melts. At this time, since the film on the plating layer is in a state of floating on the molten liquid metal Sn, the film adhesion is extremely low, and film peeling due to cooling air or film shrinkage due to internal stress of the film occurs. It becomes easy and poor film adhesion occurs. Also, when a laminate is applied on one side and a high temperature and a short time is applied on the other side, a similar film adhesion failure due to Sn melting occurs. Therefore, even if high-speed short-time high-speed coating baking is performed, free Sn that can exhibit good weldability is secured, and paint adhesion required as a material for welding cans,
A surface-treated steel sheet for a welding can, which has excellent appearance and corrosion resistance, and also has excellent film adhesion, which is essential for the properties of a laminated welding can, has been earnestly desired.

[0006]

Means for Solving the Problems The present inventors have proposed a plating structure in which free Sn remains, which suppresses alloying of Sn and exhibits excellent weldability even when high-speed and high-speed coating baking is performed. I studied hard. As a result, metal Sn
If a hydroxide layer is formed between the underlayer and the underplating layer, S
It has been found that even if high-temperature baking exceeding the melting point of n is performed, this hydroxide layer forms a barrier film and prevents Sn from alloying with the underlying metal, and a much larger amount of free Sn can be secured as compared with the prior art. .

The present invention is based on the above findings. (1) A plating amount of 5 to 55% containing Ni on the surface of a steel sheet.
A Fe-Ni alloy plating of 0 to 800 mg / m ² has a hydroxide layer, and then an area coverage of 40 to 98% formed by molten tin treatment, and a plating amount of 400 to 2500 m.
A steel plate for a welding can having excellent weldability, corrosion resistance, appearance and adhesion, which has an island-shaped Sn plating layer of g / m ² . (2) Amount of plating containing 5 to 55% of Ni on the steel plate surface 5
A Fe-Ni alloy plating of 0 to 800 mg / m ² has a hydroxide layer, and then the area coverage formed by the molten tin treatment is more than 80% and 98% or less, and the plating amount is 400.
A steel plate for a welding can having excellent weldability, corrosion resistance, appearance and adhesion, which has an island-shaped Sn plating layer of ˜2500 mg / m ² .

(3) The outermost layer has a Cr equivalent of 2 to 40 mg.
/ M ² of a chromate coating layer is formed, the steel plate for a welded can having excellent weldability, corrosion resistance, appearance and adhesion according to the above (1) or (2). (4) The area coverage of a portion of the hydroxide layer having a film thickness of 1 nm to 500 nm is 50% or more, the weldability, corrosion resistance, appearance and adhesion according to the above (1) to (3). Steel plate for welding cans with excellent properties. (5) The weldability and corrosion resistance according to (1) to (4), wherein the hydroxide is composed of one or two of Fe-based hydroxide and Ni-based hydroxide. , A steel plate for welding cans having excellent appearance and adhesion.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. In the present invention, the plating base sheet is not particularly limited, and a steel sheet usually used as a container material is used. There is no particular restriction on the manufacturing method, material, etc. of the original plating plate, and the original plate is manufactured through ordinary steps such as 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.
In the above-mentioned plating original plate, when performing plating, usually, degreasing and pickling are performed as a pretreatment for cleaning the plating original plate surface, but those methods are not particularly limited,
For example, after degreasing in 10% caustic soda, pickling may be performed in a 5% sulfuric acid solution.

After degreasing and pickling, first, a Fe-Ni alloy plating layer is formed. The purpose of the Fe-Ni alloy plating layer is to ensure corrosion resistance. The Fe-Ni alloy plating can improve the corrosion resistance of the plating layer itself by using Ni having high corrosion resistance. Furthermore, by alloying with Fe, the corrosion potential is brought closer to the base iron,
Even if there is a plating defect such as a pinhole in the e-Ni plating, the potential difference can be suppressed as small as possible, so that the progress of pitting corrosion can be suppressed.

Therefore, Fe-Ni alloy plating is practically used.
In order to exhibit excellent corrosion resistance, N per sheet of steel plate
The i content must be 5% or more and the plating amount must be 50 mg / m ² or more. Fe-Ni increases as the Ni content in the plating layer increases or the Fe-Ni alloy plating amount increases.
Although the corrosion resistance improving effect of the alloy plating increases, when the Ni content exceeds 55% or when the Fe-Ni alloy plating amount exceeds 800 mg / m ² , the corrosion resistance improving effect of the Fe-Ni alloy plating saturates. Therefore, it is economically disadvantageous. Therefore, the Ni content in the Fe-Ni alloy plating layer is 5 to 55%, and the Fe-Ni alloy plating amount is 50 to 8%.
It is necessary to set it to 00 mg / m ² .

In the present invention, the Fe-Ni alloy plating method is not particularly limited. For example, it can be obtained by an electroplating method or a heat diffusion treatment after Ni plating.
If the e-Ni alloy plating method is used, Fe-N described below is used.
Since the hydroxide layer on the i alloy plating layer can be formed at the same time when the Fe—Ni alloy plating is performed, it is industrially desirable to manufacture it by the abnormal eutectoid Fe—Ni alloy plating method.

Next, the hydroxide layer composed of one or two of Fe-based hydroxide and Ni-based hydroxide formed on the Fe-Ni alloy plating layer will be described. The role of this hydroxide layer is mainly to secure weldability. That is, the weldability mainly depends on the amount of free Sn, and the greater the amount of free Sn, the better the weldability, and conversely the free S
It is known that the weldability deteriorates as n decreases. On the other hand, Sn is alloyed with Fe or Ni as a base metal even at a melting point (232 ° C.) or less, but if it exceeds the melting point, the alloying rate of Sn remarkably increases, so that the weldability deteriorates at high temperature baking. . However, if Fe-based hydroxides or Ni-based hydroxides are present in the lower layer of the Sn plating layer, alloying with the base metal is suppressed even if the Sn metal is below or above the melting point. The reason for this is considered to be that the Fe-based hydroxide or Ni-based hydroxide has a low affinity with the metal Sn, and therefore acts as a barrier layer that prevents movement of Sn to be alloyed.

Therefore, in order to fully exert the alloying suppressing effect of Fe hydroxide or Ni hydroxide practically, it is necessary to coat the hydroxide with an area occupancy ratio of 50% or more. Further, it is desirable that this hydroxide be uniformly present in order to prevent local alloying of Sn.
If the area occupancy of the hydroxide is less than 50%, the alloying progresses from the portion not covered by the hydroxide during coating baking, and the alloying suppressing effect of the hydroxide is sufficiently exerted. Cannot be done. As the coverage of the hydroxide increases, the alloying suppression effect also increases, and the effect is maximized by complete coverage.

Further, the above-described effect of suppressing the Sn alloying of the hydroxide is exerted when the hydroxide is present at 1 nm or more. Therefore, the amount of hydroxide having an area occupation ratio of 50% or more needs to be 1 nm or more. As the thickness of the hydroxide layer becomes thicker, the effect of suppressing Sn alloying increases, but when it exceeds 500 nm, the hydroxylation has a low cohesive force, and therefore the hydroxide layer serves as an interface to cause poor adhesion due to cohesive failure. It will be easier. Therefore, the thickness of the hydroxide amount needs to be 1 nm to 500 nm. The hydroxide coverage or thickness is, for example,
It can be measured by ESCA, SIMS, EPMA or the like.

The hydroxide used in the present invention is composed of one or two of Fe-based hydroxide and Ni-based hydroxide. The hydroxide is not particularly limited, and examples thereof include Fe (OH) ₂ and Fe as Fe-based hydroxides.
O · xH ₂ O, Fe (OH) ₃ , Fe ₂ O ₃ · nH ₂ O,
FeO (OH), etc., as Ni-based hydroxide, NiOH,
Ni (OH) ₂ , Ni ₂ O ₃ · nH ₂ O, NiO (OH)
Etc. may be used. The method for forming these hydroxides is also not particularly limited. For example, an electrochemical method may be used, or a chemical reaction or vacuum deposition may be used. Industrially, as described in Fe-Ni alloy plating, it is possible to use an abnormal eutectoid Fe-Ni alloy plating method capable of simultaneously performing Fe-Ni alloy plating and formation of these hydroxides. desirable.

Next, Sn plating that has been subjected to molten tin treatment is formed on the hydroxide layer. The purpose of this Sn plating layer is to secure weldability as described repeatedly. According to the present invention, the plating amount of Sn needs to be 400 mg / m ² or more. If the plating amount is less than 400 mg / m ² , weldability deteriorates and stable and good welding cannot be obtained. When the Sn plating amount is 400 mg / m ² or more, the weldability becomes good, and as the Sn plating amount increases, the effect of improving the weldability improves, but when the Sn plating amount exceeds 2500 mg / m ² , this improvement is achieved. Since the effect is saturated, an Sn plating amount of 2500 mg / m ² or less is economically sufficient.

Further, in this Sn plating layer, it is necessary to heat the Sn to a temperature equal to or higher than the melting point by a molten tin treatment so as to repel it so that the area occupancy rate is 40 to 98%. This is because if the area occupancy of Sn exceeds 98%, the film adhesiveness deteriorates. In order to secure the film adhesiveness, the area of molten Sn is reduced, and the Fe—Ni alloy plating layer and hydroxide layer that do not melt are exposed even when the melting point of Sn is exceeded or by welding heat. As a result, excellent film adhesion can be exhibited in combination with the chromate film described later.

Therefore, the area occupancy of Sn must be 98% or less. The smaller the area occupancy rate of Sn, the greater the exposed area rate of the non-melting Fe—Ni alloy plating layer and the hydroxide layer. Therefore, the smaller the area occupancy rate of Sn, the better. However, when the area occupancy of Sn is less than 40%, S
The good weldability of n will not be exhibited, and dust will occur during welding and the nugget will not be stably generated.

Further, the appearance of the products of the present invention and the coated and laminated steel sheets using the products of the present invention depends on the Sn area ratio, and the lower the area ratio, the smaller the area of Sn having excellent appearance. , The appearance deteriorates. Area ratio of Sn is 40
% Or more, there is no problem in practical use, but the area ratio of Sn is 8
When it exceeds 0%, it begins to show an excellent beautiful appearance like a general tin plate covered with Sn on the entire surface. Therefore, the area occupancy ratio of Sn is 40 to 98%, and it is necessary to set the area ratio of Sn to more than 80% in order to exhibit more excellent appearance. In addition, Sn
The area ratio can be measured from the characteristic X-ray intensity of Sn by irradiating the sample with an electron beam having a diameter of 1 micron at 400 × 400 points.

In the present invention, the Sn plating and the subsequent molten tin treatment method are not particularly restricted. Sn
The plating can be obtained, for example, by electroplating from a Sn plating bath based on phenolsulfonic acid. Further, regarding the molten tin treatment method, for example, it may be heated to a temperature equal to or higher than the melting point of Sn by electric heating or dielectric heating. Subsequently, after the molten tin treatment, a chromate film is applied for the purpose of paint adhesion, film adhesion, and corrosion resistance (prevention of undercutting corrosion). 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 a lower layer and a chromium oxide hydrate layer as an upper layer. Pointing to. The hydrated chromium oxide layer may contain sulfate ions, fluorine ions, etc., which are plating aids described later. Film adhesion and corrosion resistance are ensured by the strong chemical bond between the functional groups of the hydrated chromium oxide and the functional groups of the film to be laminated.

However, since the hydrated chromium oxide film is an electrically insulating material, it has a very high electric resistance, and since metallic chromium has a high melting point and a high electric resistance, both are negative factors that deteriorate the weldability. For this reason, good film adhesion, corrosion resistance, and an appropriate amount of chromate film adhesion that does not practically deteriorate weldability are very important. Therefore,
Chromate film adhesion amount is 2 per side in terms of metal chrome.
４０40 mg / m ² is selected. That is, if the amount of chromate film adhered is less than 2 mg / m ² , the effects of improving the film adhesion and preventing undercutting corrosion cannot be obtained, so an amount of ² mg / m ² or more is desirable. On the other hand, if the amount of the chromate film adhered exceeds 40 mg / m ² , the contact resistance increases remarkably, scattering easily occurs due to local heat generation, and the weldability deteriorates. Therefore, the amount of the chromate film attached is regulated to 40 mg / m ² or less.

The chromate treatment method may be any of various methods such as dipping treatment with an aqueous solution of various chromic acid sodium salts, potassium salts and ammonium salts, spraying treatment, electrolytic treatment, etc., but cathodic electrolytic treatment is particularly excellent. There is.
In particular, the cathodic electrolysis treatment in an aqueous solution in which sulphate ion, fluoride ion (including ferric ion) or a mixture thereof is added to chromic acid as a plating aid is the most excellent.

[0024]

EXAMPLES Examples of the present invention and comparative examples will be described below, and the results are shown in Table 1. By cold rolling or double rolling after annealing, the plating base plate adjusted to a predetermined plate thickness is electrolytically degreased in 5% caustic soda, washed with water and then electrolytically pickled in 10% sulfuric acid, and surface-treated after surface activation. It was Fe-N was added to this plating base plate under the conditions shown in (1)-(A) to (B).
After i alloy plating and hydroxide formation, (2)-
Sn plating is performed under the conditions shown in (A) to (B), followed by heat treatment under the conditions shown in (3)-(A) to (B), and then to (4)-(A) to (C). What produced the chromate film | membrane in the processing bath shown was produced.

[0025]

[Table 1]

(1) Fe-Ni plating conditions (A) Sulfuric acid bath composition Ni ion 15 g / l, Fe ion 30
g / l, sulfuric acid ion 15 g / l, boric acid 20 g / l Plating conditions 20 to 40 ° C., 5 to 15 A / dm ² (B) Sulfuric acid-hydrochloric acid bath bath composition Ni ion 25 g / l, Fe ion 50
g / l, sulfate ion 15g / l, chloride ion 10g / l,
Boric acid 20g / l Plating condition 30-55 ° C, 5-40A / dm ²

(2) Sn plating conditions (A) Sulfuric acid bath Bath composition Sn ion 20 g / l, sulfate ion 15
g / l Plating condition 20-60 ° C, 5-30A / dm ² (B) Phenolsulfonic acid bath Bath composition Sn ion 15g / l, Phenolsulfonate ion 15g / l Plating condition 30-55 ° C, 5-40A / dm ²

(3) Heat treatment conditions (A) Induction heating method The sample was inserted into an induction heating furnace and heated to 220 ° C. for 4 to 15 s.
Electricity is applied so that the temperature rises at ec, and water is immediately cooled after completion of energization. (B) Electric heating method The electric current is applied so that the alternating current is heated up to 220 ° C. in 4 to 15 seconds, and water cooling is performed immediately after the completion of the energization.

(4) Chromate treatment conditions (A) Chromium oxide 100 g / l, sulfate ion 0.6 g
/ l Plating conditions 20 to 60 ° C., 5 to 80 A / dm ² (B) Sodium dichromate 15 to 45 g / l, Plating conditions 30 to 50 ° C., 10 to 40 A / dm ² (C) Chromic acid 80 g / l, sulfate ion 0.05 g
/ l, sodium fluorosilicate 2.5 g / l, ammonium fluoride
0.5 g / l Plating condition 15-75 ° C, 10-85 A / dm ²

Regarding the above-mentioned treated material, the following (A) to
It carried out about each item of (D), and evaluated the performance. (A) Seam weldability The test piece was prepared under the conditions of high temperature and short time baking.
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.
5 mm, pressing force 45 kgf, welding wire speed 80
Welding is carried out by changing the current under the condition of m / min, and the width of the proper current range consisting of the minimum current value at which sufficient welding strength can be obtained and the maximum current value at which welding defects such as scattering start to stand out and welding defects Was evaluated comprehensively from the occurrence situation of.

(B) Paint adhesion The surface of the test piece, which corresponds to the inner surface of the can, is coated with epoxyphenol.
55mg / dm of paint ² Apply, and also correspond to the outer surface of the can
40mg / dm of clear lacquer on the surface² Apply, 29
It was dried and hardened to 0 ° C. under a baking condition of 15 seconds. Pull
Continue, scratch each surface at 1mm intervals, about
Prepare 100 grids, peel off the tape immediately,
The peeling condition of No. 2 was observed and the paint adhesion was evaluated.

(C) Film Adhesion Evaluation Test After laminating a PET (polyethylene terephthalate) type film having a thickness of 15 μm on a test piece, a cross cut is put until the base metal is reached, and it is quickly heated to 240 ° C.,
An air gas of 5 kg / cm ² was vertically blown to the central portion of the cross cut to evaluate the peeling state of the film.

(D) UCC (Undercutting Corrosion) Evaluation Test In order to evaluate the corrosion resistance of the surface of the test piece corresponding to the inner surface of the can,
A PET (polyethylene terephthalate) film having a thickness of 15 μm was laminated on the surface corresponding to the inner surface of the can.
After that, make a cross cut until the steel reaches
The sample was immersed in a test solution composed of a mixture of 1.5% citric acid and 1.5% sodium chloride at 55 ° C. for 4 days under the open air. After the completion of the test, the scratch portion and the flat surface portion were rapidly peeled off with a tape, and the corrosion situation near the scratch portion, the pitting situation of the scratch portion and the film peeling situation of the flat surface portion were judged and comprehensively evaluated. (E) Appearance evaluation test White printed on the surface corresponding to the outer surface of the can 1
A 5 um PET (polyethylene terephthalate) film was laminated and the brightness of the color tone was evaluated.

In Table 1, Comparative Example 8 is an Fe-Ni alloy plating carried out by vacuum vapor deposition and has no hydroxide layer. Therefore, it is shown that the free Sn is not secured and the seam weldability is deteriorated. However, as shown in Examples 1 to 12 in Table 1, it was revealed that the steel plates for welded cans produced according to the present invention have excellent weldability, adhesion, appearance and corrosion resistance.

[0035]

As described above, the steel plate for a welded can produced by the present invention has excellent weldability, adhesion, appearance and corrosion resistance.

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[Procedure amendment]

[Submission date] June 26, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction contents]

[0025]

[Table 1]

Claims (5)

[Claims] 1. A hydroxide layer is formed on a Fe—Ni alloy plating having a plating amount of 50 to 800 mg / m ² containing 5 to 55% of Ni on the surface of a steel sheet, and then formed by a molten molten tin treatment. Area coverage 40-98% and plating amount 400-2
A steel plate for a welding can excellent in weldability, corrosion resistance, appearance and adhesion, which has an island-shaped Sn plating layer of 500 mg / m ² . ^2. A hydroxide layer is formed on a Fe—Ni alloy plating having a plating amount of 50 to 800 mg / m ² containing 5 to 55% Ni on the surface of a steel sheet, and then formed by a molten molten tin treatment. For a welded can excellent in weldability, corrosion resistance, appearance and adhesion, having an island-shaped Sn plating layer having a plating amount of 400 to 2500 mg / m ^{2 with} an area coverage of 80% to 98%. steel sheet. 3. The outermost surface layer has a Cr equivalent amount of 2 to 40 mg / m.
^A steel plate for a welded can having excellent weldability, corrosion resistance, appearance and adhesion, according to claim 1 or ^{2, wherein} the chromate coating layer of ² is formed. 4. The weldability, corrosion resistance, appearance and adhesion of the hydroxide layer having an area coverage of 50% or more in a portion having a film thickness of 1 nm to 500 nm. Excellent steel plate for welding cans. 5. As the hydroxide, Fe-based hydroxide, N
A steel sheet for a welding can having excellent weldability, corrosion resistance, appearance and adhesion, which is composed of one or two types of i-type hydroxides.