JPH09174186A - Easy open lid steel sheet having excellent corrosion-resistance and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy open lid steel sheet which can obviate the need of repair coating at a score part and to provide the method therefor. SOLUTION: The composition of this steel sheet contains <=0.20wt.% C, <=0.5wt.% Si, <=1.0wt.% Mn, <=0.15wt.% P, <=0.100wt.% S, <=0.150wt.% solAl, <=0.0150wt.% N, the other <=0.0070wt.% B, and the balance Fe with inevitable impurities further it contains, is necessary, <=0.0070wt.% B and one kind or more than two kinds of Nb and Ti by <=0.10wt.%, it has a score for an easy open lid on the front face of a cold rolled steel sheet with the above composition, it has an electroplating layer on the front face of steel sheet, an upper part of both side walls of a score groove and on an intermediate side wall face, and it has a coating layer on the above electroplating layer of the front face of steel sheet, and on the faces of the intermediate part, the upper part and the bottom part of both side walls of the score groove. Further, for the production therefor, the cast billet of the above composition is hot-rolled, cold- rolled and annealed for re-crystallization according to the normal method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel plate for an easy open lid having a score excellent in corrosion resistance and a method for producing the same.

[0002]

2. Description of the Related Art Recently, in a can lid such as a beverage can or a food can, a score having an appropriate shape and depth is engraved, a tab for opening the can is attached, and the tab is pulled so that the score portion is outside. P that can be torn easily and open can
Artial-EOE or by causing a tab, the score part is ruptured inward and can be opened easily, the tab remains inside and the tab does not scatter on roads, parks, etc. S
A lid of a tay-on-tab-EOE is used.

Materials of this easy open lid include steel and aluminum. The aluminum lid cannot be said to be used for all contents from the viewpoint of corrosion resistance, and steel is used especially for contents containing salt.
Also, aluminum lids are inconvenient from a recycling perspective for steel can body lids. On the other hand, the steel easy-open lid has a defect that the score part needs to be repair-painted because the plating and the coating film of the score part are destroyed by the score process to deteriorate the corrosion resistance of the score part.

As a method for improving the corrosion resistance, Japanese Patent Laid-Open No. 61-193731 discloses "Sn after score processing,
Method for producing steel plate for easy open lid having a score excellent in corrosion resistance by performing surface treatment such as Cr and Ni plating "
In addition, Japanese Patent Publication No. 63-40863 discloses "a surface-treated steel plate for an easy-open lid, which has a plurality of score-processed score parts and a coating is formed on the score parts" (however, , And all of these methods are methods whose main task is to improve can openability).

The method disclosed in Japanese Patent Laid-Open No. 61-193731 discloses, according to the specification, "a slab is hot-rolled and cold-rolled by a usual method and then recrystallized and annealed to obtain a steel sheet for a can. Then, a score is stamped on the steel sheet with a press or a roller, after which heat treatment for softening the scored portion is performed to improve the can openability, and then S
It is plated with n, Cr, Ni and shipped, and the can opener manufactures the easy open lid. This allows
It is an invention whose main technology is "improving can openability and corrosion resistance". The improvement of corrosion resistance provided by the method of the present invention is
The evaluation method of the corrosion resistance in the examples of the publication is "In addition, in Table 1, a can body is formed after the lid is made, and 1.5% citric acid and 1.5% are used.
The result of investigating the rusting condition of the can lid after being filled with a mixed solution of salt and kept at a temperature of 50 ° C. for 30 days is shown. ..... 3
Page top right 15th line ". Therefore, the inventors have evaluated the corrosion resistance of the can lid on the inside of the can and found that the corrosion resistance can be improved. That is, the invention of the same publication has not been investigated with respect to the corrosion resistance of the scored portion (the scored portion is on the outside of the can), which is a problem to be solved by the present invention.

Therefore, the inventors of the present invention focused on the corrosion resistance of the score portion of this method and conducted a detailed investigation. As a result, this method, that is, the surface treatment of the score processed portion Sn, Cr, Ni plating or the like was performed. As a result of investigating the corrosion resistance of the easy open lid manufactured by using the steel plate
It was clarified that red rust was generated in the score part under the non-repair coating condition, and the problem of the present invention could not be solved.

The method disclosed in Japanese Patent Publication No. 63-40863 is as follows.
According to the same specification, "a thin steel plate after temper rolling is pre-washed, resist-printed to give a score pattern, and then an etching treatment is performed to dissolve the base material to perform score processing, and after this score processing, resist printing is performed. TFS after removing
Surface treatment such as electrical or other plating such as plating or Sn plating, or chemical conversion coating treatment, etc .... Incidentally, those treated in this way are subjected to inner coating as appropriate,
Riveted and then sent to the can manufacturing process. This is an invention whose main technology is "improving can openability and corrosion resistance", but the method of the present invention is "after the score processing by etching, the sidewalls and bottoms of the groove of the score processing are almost uniform. Cover with Sn plating of thickness (second
The main feature is "improving the corrosion resistance of the score part", but the problem with this method is that the shape of the score processing is about 150μ in an extremely narrow width of about 100μm.
It has a sharp shape with a depth of m or more. By electroplating the side walls and bottom of the score groove to a substantially uniform thickness, the electric current is concentrated in the portion closer to the electrode in electroplating. As a result of the flow, since the sharp recess has a property that electroplating is not applied, there is a problem that it is extremely difficult to obtain the plating state of the score part shown in FIG. 2 of the publication. There is. As described above, there is still no steel plate for easy-open lid and a manufacturing method thereof that can completely eliminate the repair coating of the score part.

[0008]

The problem to be solved by the present invention is to provide a steel plate for an easy open lid which can completely eliminate the repair coating of the score portion, and a method for producing the same.

[0009]

Means for Solving the Problems The present inventors have conducted earnest studies and completed the present invention in order to provide a steel plate for an easy-open lid and a method for producing the same, which can completely eliminate repair coating of the score part. The summary is as follows. (1) C: ≦ 0.20 wt% Si: ≦ 0.5 wt% Mn: ≦ 1.0 wt% P: ≦ 0.15 wt% S: ≦ 0.100 wt% solAl: ≦ 0.150 wt% N: ≦ 0. In addition, B: ≤ 0.0070 wt% and 1 or more of Nb and Ti ≤ 0.10.
wt% as needed, the balance has a score for the easy open lid on the surface of the cold-rolled steel sheet having a composition consisting of Fe and unavoidable elements, and on the steel sheet surface and the upper side of both side walls of the score groove and the middle side wall surface. For an easy-open lid having an electroplating layer, and a coating layer on the electroplating layer on the surface of the steel plate and on the middle, lower and bottom surfaces of both sides of the score groove, which has excellent corrosion resistance. steel sheet.

(20) The steel plate for easy-open can lid excellent in corrosion resistance according to (1), wherein the electroplating layer is a Sn plating layer. (3) The electroplating layer is a Sn plating layer and this layer (1) above, characterized in that it comprises an electrolytic chromate treatment layer above
Steel plate for easy open can lids with excellent corrosion resistance described in.

(4) C: ≤ 0.20 wt% Si: ≤ 0.5 wt% Mn: ≤ 1.0 wt% P: ≤ 0.15 wt% S: ≤ 0.100 wt% solAl: ≤ 0.150 wt% N: ≦ 0.0150 wt% In addition, B: ≦ 0.0070 wt% Further, one or more of Nb and Ti are ≦ 0.10.
According to a conventional method, a steel having a composition containing wt% as necessary and the balance consisting of Fe and unavoidable elements is melted, a hot rolled steel sheet is manufactured, and a steel sheet subjected to cold rolling and recrystallization annealing is added,
An easy-open can lid with excellent corrosion resistance, which is characterized by stamping a score for the easy-open lid, correcting the shape if necessary, then performing electroplating or electroplating and electrolytic chromate treatment, and then painting. Method for manufacturing steel sheet.

(5) The method for producing a steel plate for an easy open can lid having excellent corrosion resistance as described in (4) above, wherein the electroplating is electro Sn plating. (6) The method for producing a steel plate for an easy open can lid having excellent corrosion resistance according to the above (4) or (5), which is characterized in that coating is performed with a roll coater.

The present invention will be described in detail below. The inventors of the present invention have described the above-mentioned "method for producing a steel plate for an easy open lid having a score excellent in corrosion resistance, which is subjected to surface treatment such as Sn, Cr, Ni plating after score processing in JP-A-61-193731". , Is an invention that provides a method of improving the corrosion resistance of the inner surface of the lid, not the scored portion,
Since the method of the publication is a method of performing electric Sn plating after score processing, the present inventors consider that the method has a possibility of improving the corrosion resistance of the score part, and pay attention to that, However, it was clarified that the red rust was completely generated in the score part under the non-repair coating condition, and the repair-free coating of the score part could not be achieved.

Therefore, as a result of detailed investigation on the cause, the inventors of the present invention have found that, in electroplating such as Sn, Cr, and Ni plating, the distance between the lower and bottom side walls of the score groove is smaller than that of the electrode. Since electric current hardly flows due to the distance, electroplating becomes almost impossible. As a result, electroplating is performed in the upper and middle portions of the score groove, but Sn, Cr, Ni plating, etc. in the lower and bottom portions of the score groove. It is impossible to apply electroplating, and the corrosion resistance can be slightly improved, but the repair coating on the score part cannot be eliminated. "

Therefore, in addition to electroplating, various economical methods for ensuring the overall corrosion resistance including the bottom of the score part have been investigated, and in the experiment, the score groove groove Contrary to electroplating, the coating condition of the coating film is that the top part of the score is almost covered with the paint, but the bottom part of the score is filled with the paint that has flowed and is well covered with the paint film. I found that.

If the present inventors pay attention to this finding and combine it with the knowledge obtained by the investigation of the electroplating coverage of the score groove portion electroplated after the score processing, the electroplating and the painting can be applied to each other. It was found that the weak points of No. 1 could be compensated for, and the corrosion resistance of the entire score area could be made sufficient, and the technical idea of the present invention could be found. Based on this technical idea, the inventors of the present invention, under various conditions, after score processing, electroplating and then coating with a roll coater or the like, lid-making, and evaluate the corrosion resistance of the score portion, and the score portion. The present inventors succeeded in discovering the method of the present invention by investigating the coating state of the Sn plating and the coating state of the coating film and repeating the confirmation experiment of the technical idea of the present invention.

Table 1 is a table showing a part of the experiment. In addition, the corrosion resistance of the score part was evaluated by performing a salt spray test (24 hours), and the score part was evaluated for the state of red rust. If the degree of spillage from the score part is slight, it is ×, if the rust is severely spilled, it is ×.
It was set to x. At the same time, the comparison method and the like were evaluated, and Table 1
Shown in In addition, FIG. 1 shows a schematic view of the result of investigation of the coating state of Sn plating and the coating state of the coating film of the score portion with an optical microscope and a scanning electron microscope.

[0018]

[Table 1]

No. 1 of the present invention. The method of No. 3 is No. 1, N
o. Sufficient corrosion resistance is obtained in the same manner as the method according to the reference for performing post-manufacturing maintenance coating of 5 or the current method. According to the method of the present invention, the manufactured lids are spray-repaired one by one, It is well understood that the repair coating, which is problematic both in terms of the environment where the drying process is performed and economically, can be omitted. In addition, the method of the present invention can omit maintenance painting as shown in FIG.
As shown in the method of the present invention, `` after electroplating, coating is performed by a roll coater or the like, the upper part to the middle part of the side wall of the score groove is electroplated, and the middle part to the lower part and the bottom part of the score groove are painted. By adopting a coating configuration that can complement each other's weak points, "
The corrosion resistance of the entire score part can be made sufficient. It is not possible to obtain the great merit of omitting repair painting only by electroplating.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The constitutional conditions of the present invention will be described in detail below. Regarding the steel composition of the steel plate for the easy open lid of the present invention, C, Si, Mn, P, S, solAl, and N are all elements that strengthen the material of the steel plate, and C: ≤ 0.20.
wt%, Si: ≤ 0.5 wt%, Mn: ≤ 1.0 wt
%, P: ≤0.15 wt%, S: ≤0.100 wt%,
solAl: ≤0.150 wt%, N: ≤0.0150
If the content exceeds the range of wt%, the openability of the easy-open lid will be impaired, so it is necessary to regulate to these ranges. Further, B fixes N as BN and has an action of preventing aging deterioration due to solid solution N, so it may be added as necessary, but B: ≤ 0.007
If it exceeds the range of 0 wt%, adverse effects such as the material becoming too hard will occur, so it is necessary to regulate within this range. Furthermore, one or more of Nb and Ti may be used as ≦
When added in the range of 0.10 wt%, C and N can be fixed as TiC, NbC, and TiN when a steel sheet is manufactured by the continuous annealing method, and a soft, non-aging material can be obtained. It may be added if necessary, but even if it exceeds this range, no special effect is obtained, the alloy cost increases only, it is restricted to this range, and the balance is Fe and an unavoidable element unless it is a steel composition. I won't.

The steelmaking conditions for the steel sheet for the easy-open lid of the present invention are not particularly limited as long as the steel having the above composition can be melted into a slab, and a slab can be formed by a usual method. . Hot rolling conditions, cold rolling conditions, and annealing conditions do not need to be particularly regulated, and hot rolled steel sheets are manufactured according to a conventional method, and cold rolled and recrystallized annealed steel sheets are scored for easy open lids. May be used, and any method such as recrystallization annealing, box annealing or continuous annealing may be used, and tempered rolling may be applied to the annealed steel sheet as necessary without any adverse effect. Further, there is no problem in a method in which the recrystallized annealed steel sheet is appropriately temper-rolled and then scored by etching disclosed in Japanese Patent Publication No. 63-40863. However, it goes without saying that the electroplating and coating of the present invention should be performed after the score processing, and the coating condition of the electroplating and coating of the score groove portion should be the condition of the present invention.

It is essential that the steel sheet of the present invention has a score for the easy open lid on the surface of the steel sheet, and the score portion is also electroplated after score processing and coated. The score for the easy-open lid on the surface of the steel plate is the score for the above-mentioned Partial-EOE or Stay-on-tab-EOE lid, and the entire can lid used for food cans such as salmon cans is opened. Any of the scores for full-open EOE may be used, and there is no particular need for regulation. Further, the score processing method may be a roll score transfer method, a press stamping method, or JP-B-63-4086.
There is no problem even in the method of performing score processing by etching, which is disclosed in Japanese Patent No. 3 publication.

For shape correction after scoring, when scoring is performed by a mechanical method such as rolling or pressing, elastic stress is generated around the scoring portion and the periphery rises and the shape becomes uneven. In many cases, electroplating or painting in the next process cannot be performed.
The shape may be corrected if necessary. The shape correction may be performed by a temper rolling mill or a leveler, but when the shape is not good, it is preferable to spread it by 0.3 to 1.5% by the temper rolling mill.

The electroplating after the score processing may be Sn plating which is a plating of a steel plate for an easy open lid made of steel, or Ni or Cr plating. The plating thickness is not particularly limited as long as it is within the range of the plating thickness of tin-plated steel sheet or TFS (tin-free steel sheet) that is usually used for food cans or beverage cans. The conditions of coating after plating are
It has corrosion resistance and does not need to be restricted as long as it has a viscosity that allows it to flow to the bottom of the score without the viscosity of the paint being too high. Usually, paints used for food and beverage cans. Good. Further, the coating may be performed by a commonly used method such as a roll coater before the lid is manufactured.

The electroplating and coating conditions of the coating film are shown in FIG.
As shown in "the steel plate surface and the upper and middle side walls of both sides of the score groove have an electroplating layer on the above-mentioned electroplating layer of the steel plate surface and the middle and lower and bottom surfaces of both sides of the score groove. It is indispensable to have a coating layer on each side, and by doing this, the weak points of each other can be complemented to achieve repair-free painting of the score part. It is possible to omit the repair coating, which is an economically and economically problematic problem. As for the plating after the score processing, as long as the coating conditions shown in FIG. 1 can be achieved, Cr, other than Sn plating,
Ni plating may be used. Further, if it is desired to improve the adhesion of the coating film, a chromate treatment may be performed on the electroplating to obtain more stable corrosion resistance.

[0026]

EXAMPLES The effects of the present invention will be described below with reference to examples. A slab having the composition shown in Table 2 was prepared, and steel A was heated to 1200 ° C and hot-rolled, and finish rolling was completed at 880 ° C.
Winding at 70 ° C, Steel B is heated to 1200 ° C and hot-rolled, finish rolling is completed at 920 ° C and wound at 620 ° C, Steel C is heated to 1220 ° C and hot-rolled to 840 ° C.
Finishing rolling is completed with and rolled up at 570 ° C.
2.3mm, 2.5mm, 2.0mm hot rolled steel sheets were manufactured, after pickling, each was cold rolled to 0.23mm, Steel A was continuously annealed at 670 ° C, Steel B was continuously annealed. 78 by law
At 0 ° C., Steel C was re-annealed at 670 ° C. by the continuous annealing method, and 1.0% temper-rolling was applied to each to manufacture test materials. An easy-open lid was made under the conditions of 1 to 8 and the coating state, can openability and corrosion resistance were evaluated, and the results are shown in Table 3.

[0027]

[Table 2]

[0028]

[Table 3]

As for other conditions, the score processing is Stay.
-On-tab-EOE with a score remaining thickness of 70 μm, electric Sn plating is a ferrostein bath method, and plating and coating with the plating amount shown in Table 3 is a clear coating (50 mg / dm ² ) applied to a food can with a roll coater. I went there. still,
The score (P) in Table 3 is the press method, and the score (E)
Was subjected to score processing by an etching method. The coating state was evaluated by observing the coating state of Sn and the coating film on the score portion with an optical microscope and a scanning microscope, and as shown in FIG. 1, "the electroplating layer was formed on the upper and middle side wall surfaces of both sides of the score groove. And a structure having coating layers on the middle and lower and bottom surfaces of both sides of the score groove "was evaluated as ◯, and when not achieved, was evaluated as x.

The can openability was evaluated as ◯ if the openability of the commercially available steel easy-open lid was secured, and as × if it was not achieved. To evaluate the corrosion resistance of the score part, a salt spray test (24 hours) was performed, and the score part was evaluated for the state of red rust. If nothing occurred, it was ◯, red rust occurred in the score part, but red rust occurred in the score part. Those with a slight degree of runoff were evaluated as x, and those with severe red rust runoff were evaluated as xx.

No. 1 is a reference example in which after the score processing, plating is performed, the lids are made, and then the lids that have been made are spray-repaired one by one, followed by a drying treatment, which is a problematic environmentally and economically problematic repair coating. It is a similar method. As for the evaluation results, good openability and corrosion resistance are obtained.
However, there is a problem with the above-mentioned repair painting. No. 2
Is No. In the comparative example in which the repair coating after lid making is omitted from the condition of No. 1, the coating composition condition of the score groove portion of the present invention is not satisfied because no coating is applied, and red rust occurs. No. 3, the manufacturing process is the same as the process of the present invention, but the Sn plating amount is extremely small, and the coating condition of the score groove portion of the present invention, which is the point of the coating condition of the plating and the coating film, is satisfied. In the comparative example which was not applied, red rust occurred.

No. Nos. 4, 5, and 6 are all the methods of the present invention. Nos. 4 and 5 are examples of low carbon Al killed steel having a chromate amount of 8 mg / m ² which is a condition usually used for Sn plating, and 30 mg / m ² which is an improved condition of coating adhesion. No. 6 is an example of TFS of 90 mg / m ² using ultra-low carbon steel to which Ti, Nb and B are added in combination, all of which are examples of the present invention satisfying the conditions of the coating condition of the present invention, Good openability and corrosion resistance are obtained. As described above, the steel sheet and the method for producing the same according to the present invention have good corrosion resistance and excellent industrial value even if the repair coating, which is both environmentally and economically problematic, is omitted.
No. No. 7 is a comparative example in which the Mn of the steel composition is 1.80%, which is outside the range of the present invention, and the steel sheet becomes too hard and the can openability is poor. No. No. 8 is a current method and has good can openability and corrosion resistance, but requires repair coating.

As is clear from the results of the above embodiments,
The steel sheet and the manufacturing method thereof of the present invention are sufficient to provide “a steel sheet for easy open lid and a manufacturing method thereof which can completely eliminate repair coating of the score part” of the problem to be solved by the present invention. It can be achieved and its industrial value is extremely high. The types of easy-open lids targeted by the steel plate of the present invention are Partial-EOE,
Stay-on-tab-EOE or Full-E
The effect of any lid of OE is not impaired.

[0034]

As described above, the present invention has been described in detail. However, the steel sheet and the manufacturing method thereof according to the present invention are "easy to completely eliminate repair coating of the score portion" which is a problem to be solved by the present invention. "Providing a steel plate for an open lid and a manufacturing method thereof" can be sufficiently achieved, and the industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a result of an investigation of a coating state of Sn plating and a coating state of a coating film on a score portion, which is a feature of the present invention, by an optical microscope and a scanning microscope.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C25D 7/00 C25D 7/00 Z

Claims (6)

[Claims] 1. C: ≤0.20 wt% Si: ≤0.5 wt% Mn: ≤1.0 wt% P: ≤0.15 wt% S: ≤0.100 wt% solAl: ≤0.150 wt% N: ≤ 0.0150 wt% and B: ≤ 0.0070 wt% and one or more of Nb and Ti ≤ 0.10.
wt% as needed, the balance has a score for the easy open lid on the surface of the cold-rolled steel sheet having a composition consisting of Fe and unavoidable elements, and on the steel sheet surface and the upper side of both side walls of the score groove and the middle side wall surface. For an easy-open lid having an electroplating layer, and a coating layer on the electroplating layer on the surface of the steel plate and on the middle, lower and bottom surfaces of both sides of the score groove, which has excellent corrosion resistance. steel sheet. 2. The steel plate for an easy-open can lid having excellent corrosion resistance according to claim 1, wherein the electroplating layer is a Sn plating layer. 3. The steel plate for an easy-open can lid having excellent corrosion resistance according to claim 1, wherein the electroplating layer comprises an Sn plating layer and an electrolytic chromate treatment layer on the Sn plating layer. 4. C: ≦ 0.20 wt% Si: ≦ 0.5 wt% Mn: ≦ 1.0 wt% P: ≦ 0.15 wt% S: ≦ 0.100 wt% solAl: ≦ 0.150 wt% N: ≦ 0.0150 wt% and B: ≤ 0.0070 wt% and one or more of Nb and Ti ≤ 0.10.
According to a conventional method, a steel having a composition containing wt% as necessary and the balance consisting of Fe and unavoidable elements is melted, a hot rolled steel sheet is manufactured, and a steel sheet subjected to cold rolling and recrystallization annealing is added,
An easy-open can lid with excellent corrosion resistance, which is characterized by stamping a score for the easy-open lid, correcting the shape if necessary, then performing electroplating or electroplating and electrolytic chromate treatment, and then painting. Method for manufacturing steel sheet. 5. The method for producing a steel plate for an easy open can lid having excellent corrosion resistance according to claim 4, wherein the electroplating is electro Sn plating. 6. The method for producing a steel plate for an easy open can lid having excellent corrosion resistance according to claim 4 or 5, wherein coating is performed with a roll coater.