JPH0511547B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a steel plate for containers manufactured by drawing or further ironing after drawing, and it is an object of the present invention to provide a steel plate for containers that is particularly excellent in corrosion resistance on the outer surface of the can. . (Prior Art) In recent years, cans made by drawing or drawing-iron processing have been widely used as containers for various beverages, aerosols, liquefied gases, condensers, oil filters, and the like. Among them, drawn and ironed cans (hereinafter abbreviated as DI cans) are rapidly increasing, and aluminum, aluminum alloy, or tinplate is mainly used as the material. Aluminum or aluminum alloy is an excellent material for DI cans, but tinplate is also used in large quantities due to its cost and strength. Since tin is expensive, tinplates with as little plating as possible are used to reduce the price, and at present, a plating amount of 2.8 to 5.6 g/m ² is generally used. In the case of DI cans, they are processed to strengthen them (the thickness of the can wall becomes 1/2 to 1/3 due to ironing), so
Countless defects occur in the plating layer. Therefore, painting is necessary to impart corrosion resistance. The inner surface does not necessarily need to be painted if the purpose is to use it as a container for liquefied fuel gas, condenser, oil, etc. On the other hand, if it is used for various beverages or industrial azole, internal coating is required.
Beverage cans are generally double coated, and even aerosol cans may be coated with two coats depending on the corrosivity of the contents.
Heavy painting is applied. On the other hand, the outer surface of the can also needs to be painted in most cases, and if it is left unpainted, it will rust in a short period of time and the commercial value of the finished product will be lost. For example, in the case of aerosol cans, the outer surface of the can is painted on the can wall, which is highly processed and suffers a significant deterioration in corrosion resistance, while the bottom of the can, which is less processed and less prone to plating defects, is often omitted from painting. However, since the amount of plating is 2.8 to 5.6 g/ ^m2 , and in most cases as low as 2.8 g/ ^m2 , this is hardly a problem in a dry atmosphere, but in a high humidity atmosphere or where moisture adheres. Red rust easily occurs in the environment. In addition, even if painted, items such as aerosol cans whose contents are used in relatively small quantities over a relatively long period of time may rust from defects in the paint film that occur during use. There are many things. These problems can be solved by greatly increasing the amount of plating, but in that case the price will increase since tin is expensive. Therefore, a coating that can prevent the occurrence of red rust without increasing the price is desired. Also, depending on the contents, high corrosion resistance is required for the inner surface of the can, and in such cases, as mentioned in Hikari,
_Double painting is done. Since weighing cans twice after making cans increases can prices, there is a need for materials that can provide the necessary corrosion resistance with just one coating. (Problems to be Solved by the Invention) The main object of the present invention is to dramatically improve the corrosion resistance of the outer surface of a can, especially the red rust resistance, and to provide an inexpensive, highly corrosion-resistant coating to the inner surface of the can. Aperture,
Another purpose is to provide rust plates for DI cans. (Means for Solving the Problems) The feature of the present invention is that the surface of a thin steel plate, which is the outer surface of the can, is coated with zinc with excellent red rust resistance in an amount of 5 to 20 g/ ^m2 , and then It has a tin plating layer with a plating amount of 0.5 to 3 g/ ^m2 for the purpose of improving processability and maintaining a good appearance for a long time after can manufacturing.The inner surface of the can has a plating amount of 2.8 g/m2. ~5.6
Composite steel sheet for cans with a tin plating layer of g/m ² or, if high corrosion resistance is required, a layer of aluminum or aluminum alloy foil with a thickness of 5 to 100 μm laminated through an organic resin layer of 3 to 100 μm. be. (Function) The present invention will be explained below along with its function. The film structure of the present invention is shown in FIGS. 1 and 2.
Figure 1 shows the coating structure when applied to relatively corrosion-resistant and severe contents, starting from the outer surface of the can: 1 tin plating layer, 2 zinc plating layer, 3 steel plate, 4
These are an organic resin layer and an aluminum or aluminum alloy foil layer. That is, the aluminum or aluminum alloy foil layer becomes the surface facing the inner surface of the can. Figure 2 shows the coating structure when applied to contents with relatively mild corrosion resistance, starting from the outer surface of the can: 1 tin plating layer, 2 zinc plating layers, 3 steel plates,
6 tin plating layers. That is, the tin plating layer is the surface facing the inner surface of the can. Zinc is an electrochemically less base metal than iron;
It exhibits excellent anti-corrosion effects when combined with iron. Therefore, various galvanized steel products are produced and consumed in large quantities. However, it is not used as a material for cans, which is the subject of the present invention. This is because if a galvanized surface is used for the inner surface of a can, the zinc will corrode rapidly and the performance for containers cannot be obtained. The present inventors have discovered that when a galvanized layer is on the outer surface of a can, the outer surface is in a much milder corrosive environment than the inner surface, and even a small amount of galvanized can have a sufficient rust-preventing effect through its sacrificial anticorrosive action. By applying tin plating to the surface of the galvanized layer, the rust-preventing effect can be further increased, and the inner surface can be conventionally tin-plated, or depending on the application, a higher performance anti-corrosion coating can be applied. It has been found that a material for cans with excellent both outer and inner surfaces can be obtained by this method. The reason why the amount of galvanizing is set at 5 to 20 g/ ^m2 in the present invention is that the necessary corrosion resistance cannot be obtained with less than 5 g/ ^m2 , and the ironing process in DI processing can cause sharp galvanizing, which is called galling, on the can wall. This is because the occurrence of linear defects rapidly increases. A plating amount exceeding 20 mg/m ² is excessive and uneconomical in view of the required corrosion resistance. The reason why tin plating is applied on the galvanized layer is to improve workability, especially to prevent galling during the ironing process of DI processing. Although the galvanized layer has the effect of suppressing the occurrence of galling, it is not sufficient compared to the case where the surface of the steel sheet is left as is without the plating layer. In continuous can manufacturing, galling becomes more severe as the number of cans manufactured increases, eventually leading to can breakage. With galvanizing alone, the number of cans that can be made continuously is extremely low, and improvements are needed.As a method, it is extremely effective to have a tin plating layer of 0.5 to 3 g/ ^m2 on the galvanized surface. . Tin plating amount 0.5~3
g/m ² is selected because less than 0.5 g/m ² is less effective in preventing galling, while at 3 g/m ² the galling suppressing effect is saturated, and amounts exceeding this are not only unnecessary but also This is because the price increase is large. Therefore, the most desirable amount of plating is 1 to 2 g/
^m2 . This tin plating layer not only has the effect of preventing galling, but also has the effect of suppressing corrosion of the galvanized layer without impairing its anticorrosion effect on the can base, and has the effect of preventing deterioration of the appearance over a long period of time. There is. The galvanizing layer of the present invention is formed by any method currently practiced in the steel industry or elsewhere, in which only the outer surface of the can is plated. Electroplating is preferable from the viewpoint of controlling the amount of plating or processability. Following galvanization on one side, tin plating is applied to the upper layer.
If the inner surface of the can can also be tin-plated, a predetermined amount of plating can be applied to both sides at the same time after galvanizing.
This tin plating must have excellent adhesion to the zinc plating layer, and it is easier to obtain plating with good adhesion in an alkaline plating bath than in an acidic tin plating bath. The steel plate plated with tin on both sides was immediately washed with water and dried to produce D, which is currently used for tinplate.
The finished product is made by applying a small amount of oil such as O, S, (Di Octyl Sabacate), etc., or if necessary, it is plated.
After washing with water, post-treatments such as phosphate treatment, chromic acid treatment, chromic acid-phosphate treatment, etc. are performed, and the product is made into a finished product in the same manner. If a higher degree of corrosion resistance is required on the inside of the can, tin plating is applied only to the galvanized layer on the outside of the can, and the inside of the can is washed and dried, or if better adhesion is desired, After performing the various post-treatments described above, a layer of aluminum or aluminum alloy foil is laminated via an organic resin. It is important that the organic resin layer has the function of firmly bonding the steel substrate and the aluminum foil, and the function of maintaining corrosion resistance when the anticorrosion effect of the aluminum foil is lost. It also has the function of electrically insulating between the base steel and the aluminum foil to prevent an increase in the elution rate of Fe or Al due to local battery action. The organic resin layer must maintain adhesive strength and continuity as an anticorrosion coating even after DI processing. As the organic resin having such performance, soft thermoplastic adhesives such as acrylic, polyester, polyamide, and polyolefin adhesives, synthetic rubber adhesives, and the like are preferable. The thickness of the organic fat layer is 5μm to 100μm.
This is because if the thickness is less than 100 μm, the functions necessary for the above-mentioned organic fat layer cannot be obtained, whereas at 100 μm, the adhesive performance is saturated and a thickness exceeding that is unnecessary. The thicker the organic resin layer, the better it is as a corrosion-resistant coating, but DI
Even when used as a can, sufficient performance can be obtained with a thickness of 50 μm or less. Therefore, in terms of performance and economy, 15~
A thickness of 30 μm is most desirable. The aluminum foil laminated on top of the organic resin layer has three main functions. The first is corrosion resistance. After can manufacturing, cans are painted with epoxyphenol paint or vinyl paint and put into practical use. In areas where paint film defects occur, an aluminum foil layer prevents corrosive aqueous solutions, oxygen, etc. from penetrating into the substrate. Suppresses elution of Fe. The second is improvement in can manufacturing processability. If corrosion resistance is the only issue, make the lower organic resin layer thicker, e.g.
The problem can be solved to some extent if the thickness is 50 μm or more. but,
When strong processing is applied to DI cans, the resin layer tends to adhere to the molding punch if only the resin layer is used, making it difficult for the molded can to be removed from the punch, which greatly impairs high-speed can manufacturing performance. . These difficulties can be solved by adding a metal-based composite film to the outermost surface, but
Aluminum foil is most suitable from the viewpoint of corrosion resistance, workability of the metal foil itself, price, etc. The third purpose is to protect the properties of the underlying organic layer. The aluminum foil layer prevents the organic resin layer from being destroyed by shearing force during DI processing, and allows it to remain as a layered film, thereby preventing heating (170 to 210℃) during baking of the inner surface coating after processing. ), the underlying organic resin layer melts, contributing to recovery of adhesive strength, repair of processing defects, etc., and plays an important role in helping restore a healthy film. The reason why the thickness of the aluminum foil is set to 5 to 100 μm is that if it is less than 5 μm, the effect of improving corrosion resistance will be small.
On the other hand, at 100 μm, the corrosion resistance is saturated and there is no need for a thicker layer, which is economically disadvantageous. The thus obtained can, which is formed using the surface coated with the organic resin layer and aluminum foil layer of the composite steel plate as the can inner surface, can be coated with a single coat even for various beverages and other highly corrosive contents. Demonstrates excellent performance.
DI made from the steel plate for cans obtained as above
Cans have excellent corrosion resistance even without coating on the outside of the can.
It exhibits particularly good rust resistance, and if the inner surface of the can is tin-plated, it has the same corrosion resistance as conventional tinplate, and if the inner surface of the can is made of organic resin-aluminum foil, it has better corrosion resistance than conventional aluminum or tinplate. have It exhibits even better performance when used for squeezed cans that are processed more lightly than DI processing. In the present invention, when aluminum alloy foil is laminated via an organic resin on the steel plate surface that will become the inner surface of the can, in order to improve the corrosion resistance of the steel substrate or to further improve the adhesion between the steel substrate and the organic resin. It is preferable to laminate the organic resin and aluminum foil after performing chrome plating, nickel plating, various alloy plating TFS, chemical conversion treatment, etc. on the surface of the steel substrate. Examples of the present invention are shown below. Example 1 Plating amount 10g/m ² on one side of a thin steel plate with a thickness of 0.32mm
electrogalvanized, then 1 g/m ² of tin on the galvanized surface and 5.6 g/m 2 of tin on the non-plated surface.
g/m ² , electroplated. Then 35g/35℃ at 45℃
After immersion treatment in an aqueous solution containing sodium dichromate, washing with water and drying, 2.5 mg/m ² of D, O, and S were applied. Punch out a 139mmφ disc from this plated steel plate,
1 with a diameter of 85mmφ so that the galvanized side is the outer surface of the can.
First stage aperture, then second stage diaphragm of 65mmφ,
Furthermore, ironing was performed so that the can wall thickness was 0.1 mm. The DI cans obtained in this way were degreased with a sodium phosphate degreaser, then surface treated with a chromic acid-phosphoric acid treatment bath, and 80 to 100 mg/ ^m2 of epoxyphenol paint was sprayed on the inner surface of the can. Painting, 10 at 210℃
After baking for minutes, a vinyl paint of 60 to 80 mg/m ² was sprayed and baked at 205° C. for 5 minutes. The cans thus obtained were filled with a cola-based carbonated drink, a lemon-lime-citric acid-based carbonated drink, and 0.2% benzalkonium chloride. One of the cans was placed upright in a plastic container filled with tap water and placed in a constant temperature room at 25°C. Another one is 40 cans.
It was placed vertically in a constant temperature and humidity chamber at a temperature of 95% relative humidity. In this way, the state of corrosion on the external surface of each can was investigated when stored in two ways. In addition, in order to examine the corrosion resistance of the inner surface of the can, dry
The containers were placed in a thermostatic chamber at 38°C, and the amount of iron eluted into the contents and the number of perforated containers were examined. The results are shown in Tables 1 and 2. Example 2 One side of a steel plate with a thickness of 0.30 mm was electrolytically galvanized with a plating amount of 5 g/m ² and electrolytically tin plated with a plating amount of 2 g/m ² on top of that, and then a trace amount was applied to one non-plated surface. By electrolyzing in a citric acid aqueous solution containing sulfuric acid, a TFS coating consisting of two layers, a hydrated chromium oxide layer with a deposit of 70 mg/m ² of metallic chromium and a hydrated chromium oxide layer with a deposit of 15 mg/m ² as chromium, is ground-treated. did. A maleic acid-modified polypropylene adhesive with a thickness of 15 μm was applied to the chromium coated surface of this steel plate, and 180
A laminated film was formed by bonding aluminum foil with a thickness of 10 μm at ℃. The inner surface of this steel plate was coated with 80 to 100 mg/ ^m2 of epoxyphenol paint and heated at 210℃ for 10 minutes.
A DI can was prepared in the same manner as in Example 1, except for firing, and was subjected to a performance test. The results are shown in Tables 1 and 2. Example 3 A plating amount of 15 g/m ² was applied to one side of a steel plate with a thickness of 0.28 mm.
electrogalvanized and the amount of plating on it is 0.5g/m ²
Electro-tin plating was applied, and then a 20 μm thick aluminum foil was laminated on one non-plated surface with a 20 μm thick polyester adhesive interposed therebetween. A DI can was prepared using this steel plate in the same manner as in Example 2, and subjected to a performance test. The results are shown in Tables 1 and 2.
Shown in the table. Comparative example 1 Plate thickness 0.32mm, plating amount #25/25 (#25: 2.8g/
A DI can was made from a tin plate of 1.0 m ² ) in the same manner as in Example 1, and a performance test was conducted. The results are shown in Tables 1 and 2. Comparative example 2 Plate thickness 0.32mm, plating amount #50/50 (#50: 5.6g/
A DI can was made from a tin plate of 1.0 m ² ) in the same manner as in Example 1, and a performance test was conducted. The results are shown in Tables 1 and 2. Comparative Example 3 One side of a steel plate with a thickness of 0.32 mm was electrolytically galvanized with a plating amount of 15 g/m ² , and then the other side was electrolytically tin plated with a plating amount of 5.6 g/m ² . Regarding this steel plate, a DI can was prepared in the same manner as in Example 1, and a performance test was conducted. The results are shown in Tables 1 and 2. Tables 1 and 2 show that when cans are made using the steel sheet for cans of the present invention, the corrosion resistance is better on both the outer surface and the inner surface of the can compared to the comparative example, and the corrosion resistance on the outer surface of the can is particularly good. It is excellent.

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[Table] (Effects of the Invention) (1) The steel plate for cans of the present invention dramatically improves the corrosion resistance of the outer surface of the can after can manufacturing, and eliminates the need to paint the outer surface of the can, thereby reducing costs. (2) The corrosion resistance of the inside of the can is also superior to that of conventional products.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory diagram of the composite steel sheet of the present invention, and FIG. 2 is a cross-sectional explanatory diagram showing another example of the composite steel sheet of the present invention. 1...Tin plating layer, 2...Zinc plating layer, 3...
... steel plate, 4 ... organic resin layer, 5 ... aluminum or aluminum alloy foil, 6 ... tin plating layer.

Claims (1)

[Claims] 1. The amount of plating on the surface that becomes the outer surface after canning of the thin steel sheet is 5.
It has a galvanized layer of ~20 g/m ² and a tin plating layer with a plating amount of 0.5 to 3 g/m ² on the galvanized layer,
An organic resin layer with a thickness of 5 to 100 μm on the inner surface after can manufacturing, and a layer of 5 to 100 μm in thickness on the organic resin layer.
A composite steel sheet for cans, characterized by laminating aluminum or aluminum alloy foil. 2 Plating amount 5 on the surface that becomes the outer surface after canning of the thin steel plate
It has a galvanized layer of ~20 g/m ² and a tin plating layer with a plating amount of 0.5 to 3 g/m ² on the galvanized layer,
A composite plated steel sheet for cans, characterized by having a tin plating layer with a plating amount of 1 to 6 g/m ² on the surface that becomes the inner surface after can manufacturing.