JP2002346672A - Manufacturing method for aluminum di can body, and aluminum di can body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a fault in outside surface appearance of a DI aluminum can body when the can body is manufactured. SOLUTION: An aluminum thin plate or aluminum alloy thin plate is punched off in a bottomed cylindrical cup shape, and the can body having the bottomed cylindrical cup shape is formed by a DI machining method. After the inner and outer faces of the can body is degreased and washed, a chemically inert undercoating film e.g. an undercoating film having oxide or hydroxide whose main component is aluminum as a main component is formed on the surface of the can body. After washed with water, the can body is washed with pure water and dried at high temperature, thus the aluminum DI can body is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottomed aluminum DI can (drawing and ironing can) formed of a thin aluminum or aluminum alloy sheet, and in particular, to prevent brown discoloration (brown spot) on the inner and outer surfaces of the can. The present invention relates to a method for manufacturing an aluminum DI can body and an aluminum DI can body.

[0002]

2. Description of the Related Art Conventionally, aluminum DI cans (aluminum squeezed ironing cans) have been widely used as beverage can containers under internal pressure, such as beer and carbonated beverages. Recently, teas such as fruit juices, coffee, green tea, and oolong tea have been widely used. It is also being used for beverage containers and the like.

[0003] A method of manufacturing an aluminum DI can is generally manufactured by the following steps. First, 3004 materials, 3
A well-known aluminum thin plate for aluminum made of aluminum or an aluminum alloy such as 104 material is punched into a bottomed cylindrical cup shape, and drawn and ironed to form a bottomed cylindrical aluminum DI can body. When a thin aluminum plate for a can is punched into a cup shape and drawn and ironed, a lubricating oil composed of mineral oil, synthetic oil, or the like is usually used as a couple bricant agent or a coolant for DI ironing. Lubricating oil is attached to the can body. Further, a coating of aluminum oxide or the like is formed on the surface of the aluminum thin plate.

[0004] Thereafter, in order to form a good chemical conversion coating on the bottomed cylindrical aluminum DI can, the inner and outer surfaces of the bottomed cylindrical aluminum DI can are subjected to oil removal using a degreasing agent containing an etching agent. A washing process is performed, and then a washing process is performed. As such a degreasing agent, a degreasing agent containing an etching agent for the aluminum surface and a surfactant for removing an oil component is used.

Next, a surface cleaning treatment is performed to form a chemical conversion coating on the inner and outer surfaces by subjecting the bottomed cylindrical aluminum DI body after water washing to a chemical conversion treatment. As such a chemical conversion treatment agent, a chromium-based, zirconium-based, titanium-based chemical conversion treatment agent containing a fluoride is used (for example,
JP-B-57-39314, JP-A-10-3171
No. 62, etc.).

[0006] Further, printing is performed on the outer surface of the can body portion of the bottomed cylindrical aluminum DI can having the chemical conversion coating film formed thereon, and a protective coating is applied on the inner surface. Then, after printing and painting, a bottomed cylindrical aluminum D is formed by performing neck-in processing for reducing the diameter of the opening end of the aluminum DI can body, flange forming processing for forming a flange portion for tightening the can lid, and the like.
The I can is completed. The bottomed cylindrical aluminum DI can is filled with the contents and then wound around a separately manufactured can lid at the opening end to form an aluminum DI can.

Hitherto, in order to improve the adhesion of the coating film and the corrosion resistance of the aluminum DI can after the degreasing and washing, a phosphoric acid chromate treatment and a zirconium-based non-chromate treatment have been applied as a chemical conversion treatment. Phosphoric acid chromate treatment, albeit at a chromate-based film, Cr ⁶⁺ in the film
It has been used as a surface treatment for aluminum DI cans from the beginning because it does not elute chromium and has good coating adhesion and corrosion resistance because it does not contain chromium. System processing has become mainstream. However, zirconium-based treatment is superior to phosphoric acid chromate treatment in terms of environmental pollution,
As in the case of the phosphoric acid chromate treatment, there is still a problem that it contains a fluoride and the wastewater treatment in the surface treatment step is costly. In addition, the zirconium-based treatment has a problem that, when the coating amount is large, the coating film is peeled off in a molding step (for example, necking or flanging) after coating and printing. On the other hand, if the coating amount is small, the bare corrosion resistance becomes insufficient, and there is a problem that the pasterizer after filling and winding the inner solution causes blackening on the outer surface of the bottom of the can and significantly impairs the appearance.

Further, the water-based ink or water-based paint used for printing or protective coating applied to the surface of the can body has a lower adhesion to the aluminum base treatment film than conventional solvent-based resins, so that the adhesion is improved. Therefore, it is necessary to reduce the thickness of the surface treatment film, and there is a problem that brown discoloration which appears to be an oxidation reaction with the base metal occurs in a drying step in a drying oven. This brown discoloration is an appearance defect called a so-called brown spot. Aluminum and water react under high temperature to form an oxide film,
At this time, when the water is pure water, an oxide film called a boehmite film grows remarkably and becomes brown, which is a cause of the generation of a brown spot. Such brown spots are generated on the inner and outer surfaces of the can where water droplets adhere. Once a brown spot is formed, the properties of the can body surface become non-uniform, so even after printing and painting, ink unevenness occurs on the outer surface of the can body, and the color tone with other parts on the inner body surface of the can However, there is also a problem that appearance defects are caused.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an improved method for manufacturing an aluminum DI can and an aluminum DI can that solve the above-mentioned conventional problems. That is, it is an object of the present invention to provide a method of manufacturing an aluminum DI can and a method of manufacturing an aluminum DI can, in which the bath solution for surface treatment is relatively easily drained during the manufacture of the can, and the occurrence of defects in the surface appearance of the can is prevented. To provide a can body.

[0010]

DISCLOSURE OF THE INVENTION The aluminum D of the present invention
The method of manufacturing the I can body is as follows: an aluminum thin plate or an aluminum alloy thin plate is punched into a bottomed cylindrical cup shape, a bottomed cylindrical can body is formed by a DI processing method, and the inner and outer surfaces of the can body are degreased and washed. The method is characterized in that a chemically inert treatment film is formed on the surface of the can body, and then the body is washed with water, further washed with pure water, and dried at high temperature. In such a manufacturing method, the means for forming the treatment film may be a method of forming a treatment film mainly composed of an oxide or hydroxide mainly composed of aluminum on the surface of a can body, or a method of forming a treatment film of 1 to 100 in terms of phosphoric acid.
Preferably, 0 ppm of a phosphoric acid aqueous solution or a phosphate aqueous solution is brought into contact with the surface of the can body. Further, the aqueous phosphoric acid solution or the aqueous phosphate solution may further contain 1 to 1000 pp.
An aqueous solution to which hydrogen peroxide having an m concentration is added is preferable. In the method for producing an aluminum DI can of the present invention, an aluminum thin plate or an aluminum alloy thin plate is punched into a bottomed cylindrical cup shape, a bottomed cylindrical can is formed by DI processing, and the inner and outer surfaces of the can are cleaned. It is characterized in that it is washed with degreasing water, then with pure water, a chemically inert treated film is formed on the surface of the can body, and then the can body is dried at a high temperature. In such a production method, the means for chemically inactivating is a method in which a treatment film mainly composed of an oxide or hydroxide mainly composed of aluminum is formed on the surface of a can body, or a method in which phosphoric acid is converted to 1%. It is preferable that an aqueous solution of phosphoric acid or an aqueous solution of phosphate of about 1000 ppm is brought into contact with the surface of the can body. Further, the phosphoric acid aqueous solution or the phosphate aqueous solution is preferably an aqueous solution to which hydrogen peroxide having a concentration of 1 to 1000 ppm is further added. In the aluminum DI can of the present invention, an aluminum thin plate or an aluminum alloy thin plate is punched into a bottomed cylindrical cup shape, a bottomed cylindrical can is formed by DI processing, and the inner and outer surfaces of the can are degreased and washed with water. After that, a chemically inert treatment film is formed on the surface of the can body, and thereafter, the surface of the can body is washed with water, further washed with pure water, and dried at a high temperature. it is desirable amount is 0.01 to 1.0 mg / ^{m 2.} Further, the aluminum DI can of the present invention is formed by punching an aluminum thin plate or an aluminum alloy thin plate into a bottomed cylindrical cup shape, forming a bottomed cylindrical can by DI processing, and degreasing the inner and outer surfaces of the can. After washing with water, washing with pure water, a chemically inert treatment film is formed on the surface of the can body, and then dried at a high temperature. The treatment film has an adhesion amount of phosphorus of 0.01%. ~1.0mg / ^{m 2}
It is desirable that In the present invention, “pure water”
The term “water” refers to water having an electric conductivity of 1 μS / cm or less, and includes deionized water and distilled water.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The method of manufacturing an aluminum DI can according to the present invention is as follows. A thin aluminum sheet or aluminum alloy sheet is punched into a bottomed cylindrical cup shape, and a bottomed cylindrical can body is formed by DI processing. Then, after washing the inner and outer surfaces of the can body with degreasing water, a layer mainly composed of aluminum-based oxide or hydroxide is formed on the surface of the can body to chemically inactivate the aluminum surface, The can is washed with pure water and dried at high temperature. As a can body material used in the present invention, an aluminum thin plate or an aluminum alloy thin plate can be used.

Examples of the aluminum alloy sheet include aluminum-manganese alloy sheets such as 3004 and 3104 which are excellent in corrosion resistance and workability.

The thickness of the aluminum sheet or aluminum alloy sheet is generally 0.10 to 1.00 mm. Preferably 0.18 to 0.5
It has a thickness of 0 mm. The aluminum can body of the present invention is manufactured from the above-described aluminum thin plate or aluminum alloy thin plate by a conventionally known DI working method.

First, an aluminum thin plate or an aluminum alloy thin plate is punched into a circular shape, and formed into a shallow cup shape with a bottomed cylinder by drawing at a drawing ratio of 1.1 to 3.0. The cup is redrawn and ironed with a DI working punch and die while applying lubricating oil to form an aluminum DI can with a redrawing ratio of 1.1 to 2.0 and an ironing of 10 to 80%. I do.

(Degreased water washing) After DI processing, DI cans with lubricating oil are collected at the entrance of the washer process at a high speed with the bottom of the can facing upward, spread in the width direction of the washer device, and sent onto a mat conveyor. And degreased and washed.
The DI can body to which the lubricating oil is adhered is degreased and washed through light pre-washing with water and then through a preliminary degreasing / degreasing / water washing process.

(Formation of Treated Film) A chemically inert treated film is formed on the aluminum surface of the can body. For example,
Phosphorus adhesion on aluminum surface of can body
A 1.0 mg / m ² treated coating is formed, making the aluminum surface chemically inert. Examples of the treated film include H ₃ PO ₄ , (NH ₄ ) H ₂ PO ₄ , NaH ₂ PO ₄ , N
_{a 2 HPO 4, KH 2 PO} 4, K 2 HPO 4 phosphate alkali metal salts such as, calcium phosphate, or a phosphate alkaline earth metal salts such as magnesium phosphate and the like.

The concentration of the aqueous solution of phosphoric acid or the aqueous solution of phosphate in the treatment bath is 1 to 1000 ppm in terms of phosphoric acid. A preferred lower limit is 1 ppm in terms of phosphoric acid, and a more preferred lower limit is 1.5 ppm. 1p in terms of phosphoric acid
pm, the amount of phosphorus attached is 0.01 mg / m ^2.
The above-mentioned good film is not formed, and there is no effect in preventing the generation of brown spots. Although the upper limit is 1000 ppm,
Preferably it is 500 ppm. 1000ppm upper limit
The reason is that even if an aqueous solution having a higher concentration is applied, the effect of the treated film is converged without forming a film having a phosphorus adhesion amount of 1.0 mg / m ² or more. Therefore, the most preferred range is from 1.5 to 500 ppm. The treatment bath may be further added to a phosphoric acid aqueous solution or a phosphate aqueous solution,
A treatment bath to which hydrogen peroxide having a concentration of about 1000 ppm is added is preferable. The use of a treatment bath to which hydrogen peroxide is added promotes the formation of the chemically inert treatment film,
It is considered that the phosphorus content in the treated film can be effectively increased. In particular, when a treatment bath to which hydrogen peroxide is added in addition to the phosphoric acid aqueous solution or the phosphate aqueous solution is used, even if the concentration of the phosphoric acid aqueous solution or the phosphoric acid aqueous solution is low, the amount of deposited phosphorus can be effectively increased. When the concentration of hydrogen peroxide is less than 1 ppm, it is impossible to effectively increase the amount of phosphorous adhering.
Even if the concentration exceeds m, the effect converges.

As a means for forming a treatment film on the aluminum surface, a phosphoric acid aqueous solution or a phosphate aqueous solution is brought into contact with the surface of the can body. For example, means for immersing the can body and spraying on the surface of the can body may be mentioned. The dipping and spraying time is preferably from 2 to 60 seconds, preferably from 5 to 3 seconds.
0 seconds. If the time is less than 2 seconds, a good film is not formed, and there is no effect in preventing the generation of brown spots. If it exceeds 60 seconds, the treated film does not change, but the productivity is reduced. Therefore, the most preferable range is 5 to 30 seconds.

The temperature of the treatment bath is preferably 5 to 80 ° C, more preferably 10 to 60 ° C. If the temperature is lower than 5 ° C., a good film is not formed, and there is no effect in preventing brown spots from occurring. If the temperature exceeds 80 ° C., problems may occur in workability, equipment, and line productivity. Therefore, the most preferable range is 10 to 60C.

(Drying) In the degreasing and washing step, spraying is performed from above and below the can, and water droplets remain on the outer surface of the can at the contact portions between the cans even in the drying step. On the inner surface of the can, the center of the downwardly facing can bottom dome is at the lowest position, so that water droplets remain to the end even in the drying process. Conventionally, it is considered that water droplets remaining in the contact portion between the cans and the dome of the can bottom were exposed to a high temperature in a drying oven, and the aluminum alloy in this portion turned brown, which led to the generation of brown spots. In the present invention, since the above-mentioned treated film is formed, it does not change to brown due to the reaction with water droplets to generate a brown spot.

In the above description, in the method for manufacturing an aluminum DI can body, an aluminum thin plate or an aluminum alloy thin plate is punched into a bottomed cylindrical cup shape, and a bottomed cylindrical can body is formed by DI working method. After cleaning the inner and outer surfaces of the can body with degreasing water, a layer mainly composed of an oxide or hydroxide mainly composed of aluminum is formed on the surface of the can body to chemically inactivate the aluminum surface, and then to purify pure water. In the order of washing the can body and drying at high temperature in
4, the method is referred to as “Method A”).
In the present invention, the step of cleaning the can body with the pure water can be set before the aluminum surface is chemically inertized.

That is, an aluminum thin plate or an aluminum alloy thin plate is punched into a bottomed cylindrical cup shape, and DI
A bottomed cylindrical can body is formed by a processing method, the inner and outer surfaces of the can body are degreased and washed with pure water, and the surface of the can body is mainly composed of an oxide or hydroxide mainly composed of aluminum. In this process, the aluminum surface is chemically inertized, and then the can body is dried at a high temperature. Even in such a process sequence, the effect of the present invention of preventing appearance defects on the surface of the aluminum DI can is similarly exhibited.

[0023]

Next, the aluminum DI can of the present invention and its manufacturing method will be described in more detail with reference to examples.
In this example, an aluminum DI can was manufactured as follows. First, an aluminum alloy thin plate (3004 material) having a thickness of 0.30 mm is punched into a cup shape with a bottom using a conventional method, and subjected to drawing and ironing (DI processing).
An aluminum DI can for 0 ml was formed. Next, the following treatment was performed on the surface of the DI can body by a spray method. First, Nippon Paint Co., Ltd. degreasing agent Surf Cleaner NH
The base surface of the aluminum DI can was degreased and washed using C260, and then washed with water.

Next, <Method A: the method of claims 1 to 4> Using a phosphating bath having a different composition and concentration (Table 2), the amount of phosphorous adsorbed in terms of the amount of phosphorous was reduced to 0.1.
An inert coating in the range of 01-1 mg / m ² was formed. Then, it was washed with water and further with pure water. Table 1 (a) shows the processing conditions of each step. <Method B: The method of claims 5 to 8> After the above-described degreasing and water washing, washing with pure water, and then using a phosphating bath (Table 2) having a different composition and concentration, the amount of phosphorus is calculated in terms of phosphorus. Adhesion amount 0.01
An inert coating in the range of １1 mg / m ² was formed. Table 1 (b) shows the processing conditions of each step. Then method A or B
Processed cans are in an inverted state (can bottoms up)
Then, in a state where the cans were densely packed so as to be in contact with each other, the cans were heated and dried in an oven at an ambient temperature of 240 ° C.

[0025]

【table 1】

The measurements and evaluations shown in Examples and Comparative Examples were performed as follows. 1) Amount of Phosphorous Adhesion The amount of phosphorus adhering to the can body in each treatment solution was measured by cutting out the outer surface of the can body and using a fluorescent X-ray spectrometer ZSX100e manufactured by Rigaku Corporation. Table 2 shows the evaluation results. 2) Appearance evaluation 1 (discoloration) Sampling and observing 100 cans after drying, 50 mm ²
The state of occurrence of the above discoloration area was evaluated. The b * value was measured for the degree of discoloration using a spectral color difference meter NF333 manufactured by Nippon Denshoku Industries Co., Ltd., and evaluated based on the number of cans in which the following three levels of discoloration occurred.
Table 2 shows the evaluation results. When the b * value was ≧ -4, the color changed to brown, and a brown spot was generated, causing a problem in appearance. In the case of -4> b * value> -7, the discoloration was slight and was within an acceptable range. In the case where the whole can was good in appearance without discoloration, the value of -7 ≧ b * was obtained in any part. For convenience, in Table 2, the b * value is described as b. 3) Appearance evaluation 2 (water stain) 100 cans after drying were sampled, observed, and evaluated by the number of cans of water stains which could be visually confirmed. Table 2 shows the evaluation results. The water-stained portion has poor adhesion to the coating film, and causes peeling of the coating film during the winding process.

[0027]

[Table 2]

From the results shown in Table 2, the DI cans of Examples 1 to 13 produced by the production method according to the present invention showed that no brown spots were observed on the sample surface by visual observation.
Alternatively, the rate of occurrence was small due to light discoloration and was in an acceptable range, and the appearance was excellent without occurrence of water stain. On the other hand, in Comparative Example 1, a hem-colored brown spot was observed on the outer surface of the can and the inner surface of the can bottom due to the treatment with water only, and this portion was clearly recognizable even by daylight. Even after the application, printing unevenness remained. Even on the inner surface side of the can, the portion where the brown spot occurred appeared different in color tone from the other portions even after the inner surface coating. Comparative Example 2
In the DI can manufactured by the conventional zirconium phosphate treatment, the appearance was not problematic, but the occurrence rate was small but water stain was generated. Further, as shown in Comparative Example 3, the water stain was definitely generated in the method B. Further, in Comparative Examples 2 and 3,
Wastewater treatment costs are also high.

[0029]

As is apparent from the above description, the method of manufacturing an aluminum DI can of the present invention comprises punching a thin aluminum plate or thin aluminum alloy plate into a bottomed cylindrical cup shape, and forming the bottomed cylinder by DI processing. To form a can-like body
After the inner and outer surfaces of the can body are degreased and washed with water, a chemically inert treatment film, for example, a treatment film mainly composed of aluminum-based oxide or hydroxide is formed on the surface of the can body, and then washed with water. Furthermore, the can body is washed with pure water and dried at a high temperature to produce an aluminum DI can body, so that it is possible to reliably obtain an excellent aluminum DI can body having no appearance defect.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) C23C 22/08 C23C 22/10 22/10 B65D 1/00 C F term (reference) 3E033 AA06 BA09 EA10 FA10 GA02 4K026 AA09 AA25 BA03 BB07 CA23 CA35 DA03 DA06 DA11 EA08

Claims (12)

[Claims] An aluminum thin plate or an aluminum alloy thin plate is punched into a bottomed cylindrical cup shape, a bottomed cylindrical can body is formed by DI processing, and the inner and outer surfaces of the can body are degreased and washed with water. A method for producing an aluminum DI can, comprising forming a chemically inert treatment film on the surface of the can, then washing with water, further washing the can with pure water, and drying at a high temperature. 2. The aluminum DI can body according to claim 1, wherein the means for forming the treated film forms a treated film mainly composed of an oxide or hydroxide mainly composed of aluminum on the surface of the can body. Manufacturing method. 3. The method for forming a treated film comprises bringing a phosphoric acid aqueous solution or a phosphate aqueous solution of 1 to 1000 ppm in terms of phosphoric acid into contact with the surface of a can body.
A method for producing the aluminum DI can as described above. 4. The method for producing an aluminum DI can according to claim 3, wherein the aqueous phosphoric acid solution or the aqueous phosphate solution is an aqueous solution to which hydrogen peroxide having a concentration of 1 to 1000 ppm is further added. 5. An aluminum thin plate or aluminum alloy thin plate is punched into a bottomed cylindrical cup shape, a bottomed cylindrical can body is formed by DI processing, and the inner and outer surfaces of the can body are degreased and washed with pure water. And forming a chemically inert treatment film on the surface of the can body, followed by drying the can body at a high temperature. 6. The aluminum DI can body according to claim 5, wherein the means for forming the treated film forms a treated film mainly composed of aluminum-based oxide or hydroxide on the surface of the can body. Manufacturing method. 7. The means for forming the treated coating is to contact a phosphoric acid aqueous solution or a phosphoric acid aqueous solution of 1 to 1000 ppm in terms of phosphoric acid with the surface of the can body.
A method for producing the aluminum DI can as described above. 8. The method for producing an aluminum DI can according to claim 7, wherein the phosphoric acid aqueous solution or the phosphate aqueous solution is an aqueous solution to which hydrogen peroxide having a concentration of 1 to 1000 ppm is further added. 9. An aluminum thin plate or aluminum alloy thin plate is punched into a bottomed cylindrical cup shape, a bottomed cylindrical can body is formed by a DI processing method, and the inner and outer surfaces of the can body are degreased and washed with water. An aluminum DI can body formed by forming a chemically inert treatment film on the surface of the can body, then washing with water, further washing the can body surface with pure water, and drying at high temperature. 10. An aluminum sheet or an aluminum sheet.
Punching a thin gold plate into a bottomed cylindrical cup shape, DI processing method
To form a bottomed cylindrical can body, the inner and outer surfaces of the can body
After degreasing and washing, the surface of the can body is treated with a chemically inert treatment.
After that, the surface of the can is washed with pure water and
An aluminum DI can that has been washed and dried at high temperature.
The treated film has an amount of phosphorus of 0.01 to 1.0 m.
g / m² Aluminum DI can characterized by being
body. 11. An aluminum thin plate or an aluminum alloy thin plate is punched into a bottomed cylindrical cup shape, a bottomed cylindrical can body is formed by DI processing, and the inner and outer surfaces of the can body are degreased and washed with pure water. An aluminum DI can body obtained by washing the above, forming a chemically inert treatment film on the surface of the can body, and then drying at high temperature. 12. An aluminum thin plate or an aluminum alloy thin plate is punched into a bottomed cylindrical cup shape, a bottomed cylindrical can body is formed by DI processing, and the inner and outer surfaces of the can body are degreased and washed with pure water. Cleaning, forming a chemically inert treatment film on the surface of the can body, followed by drying at a high temperature, wherein the treatment film has an adhesion amount of phosphorus of 0.01 to An aluminum DI can having a content of 1.0 mg / m ² .