JPH0822990B2 - Aluminum material with no peeling of printing ink or resin coating during stretch forming - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a molding used for containers and caps of jelly, pudding, meat, vegetables, prepared foods, etc., or caps of food and drink containers such as drinks, whiskeys and juices. The present invention relates to an aluminum material for use, in particular, an aluminum material which does not peel off printing ink or resin coating film during bulging.

In this specification, the term aluminum is used to include an aluminum alloy.

2. Description of the Related Art Conventional Problems and Problems Generally, printed or resin-coated aluminum materials are used for food and drink containers, caps, and the like. Such printing or resin coating is performed to improve the aesthetic appearance of the container or cap or to prevent corrosion of aluminum by the contents of the container.

However, such printing and resin coating conventionally have the following drawbacks because they are applied on the surface of an aluminum base material after an undercoat called a size coat is applied thereon. That is, the ink or coating peels off when the bulge molding process is performed, or the adhesiveness of the ink or coating decreases when the container is filled with jelly, cooked food, drink, etc. after retort sterilization after molding. However, there is a drawback that the coating film may be peeled off and the aluminum substrate may be corroded due to the contents of the container during long-term storage.

Some users also want to omit the size coat and apply printing or resin coating directly to the surface of the aluminum substrate, but if the size coat is omitted, peeling of the ink and coating film will still occur. Realization was difficult.

On the other hand, in order to eliminate the above drawbacks, it is also known to form a phosphoric acid-chromate film as a base film on the surface of the aluminum substrate, and to perform resin coating or printing through the film, The adhesiveness of the coating film and the ink was still insufficient. Further, the chromate treatment for forming the film takes time and labor, and the treatment liquid is toxic, which causes a problem in waste liquid treatment.

The present invention has been made based on such a background, and by forming a novel undercoat film instead of the phosphoric acid-chromate film, a size coat becomes unnecessary, and an ink or a coating film at the time of retort treatment is formed. Not only can it prevent adhesion deterioration, prevent film peeling due to contents during long-term storage of food, etc. and corrosion of aluminum base material, but also have excellent adhesiveness with printing ink and resin to be coated. It is an object of the present invention to provide an aluminum material for caps, which does not cause peeling of ink or coating film at the time, and has improved workability during film formation.

Means for Solving the Problems In order to achieve the above object, the aluminum material according to the present invention is, as shown in FIG. 1, an undercoat film for printing or resin coating on the surface of an aluminum substrate (1). As the polyacrylamide resin film (2) containing one or more kinds of metal compounds, the adhesion amount of the metal compound (at least one of them when two or more kinds of metal compounds are contained) is 0.1 mg / It is characterized in that a coating is formed in a state defined to be m ² or more, and the base film is subjected to printing or resin coating to be stretch-molded.

The composition of the aluminum base material (1) is not particularly limited as long as it has the stretchability and other properties required for containers, caps and the like.

The polyacrylamide resin film (2) containing a metal compound as a base film is formed through a coating and drying process using a mixed aqueous solution of a metal compound and a polyacrylamide resin as a treatment liquid. Here, as the metal compound, a zirconium compound can be cited as a preferable example. Further examples of the zirconium compound include ammonium zirconium carbonate, alkali salts of fluorozirconate, ammonium salts, zircon hydrofluoric acid, and the like. However, particularly when zirconium fluoride is used, the film is formed by the action of fluorine. (2) It is preferable in that the adhesiveness of itself to the aluminum substrate (1) can be made higher and can be eliminated. The metal compound contained in the film may be not only one type but also two or more types.
A preferable example of the combination of two or more kinds of metal compounds is a combination of a zirconium compound and a chromium compound.
This is because the corrosion resistance of the coating can be further improved by containing the chromium compound. Here, examples of the chromium compound include salts thereof containing chromium fluoride and various salts containing trivalent chromium.

Regarding the mixing ratio of the metal compound and the polyacrylamide resin in the treatment liquid as described above, when the metal compound is one kind, the content ratio of the metal compound and the polyacrylamide resin in the film is polyacrylamide to metal compound 1. The mixing ratio of the resin is preferably 0.5 to 20, and more preferably 1 to 10. Also 2
Even when a metal compound of one kind is contained, it is preferable to mix the polyacrylamide resin in a ratio of 0.5 to 20, preferably 1 to 10 with respect to the total amount of the metal compound of 1 in the film. . As a method of applying the treatment liquid, any method such as a spray method, a dipping method, a roll coating method, a brush coating method can be adopted. Further, it is desirable that the drying after coating is performed at a temperature of about 15 to 300 ° C. The drying time varies depending on the drying temperature, but is preferably about 30 seconds at 100 to 150 ° C, for example.

By the way, in the present invention, the resin film is formed in a state in which the amount of the metal compound (at least one of the two or more kinds of metal compounds in the case of containing two or more kinds) is regulated to 0.1 mg / m ² or more. It is a requirement. This is because if it is less than 0.1 mg / m ² , the adhesiveness to the coating film and the printing ink during the overhang forming process will be poor and the corrosion resistance will also be poor.
When two or more kinds of metal compounds are contained, the amount of the other remaining metal compounds is preferably 0.1 mg / m ² respectively.
The above is better. Conversely, the amount of metal compound deposited is 2000 mg / m
^It is desirable to set it to ² or less. This is because even if the amount of adhesion exceeds 2000 mg / m ² , not only the effect of improving the adhesiveness of the coating film cannot be remarkably increased, but also the adhesiveness may be deteriorated. The preferred deposition range is 0.5-500 mg / m ² for any metal compound. The deposition amount of the metal compound may be set by setting the mixing ratio of the metal compound and the polyacrylamide resin in the process of producing the treatment liquid, or by adjusting the coating amount of the treatment liquid on the aluminum substrate. good. The final coating amount is preferably 0.5 to 5000 mg / m ² from the viewpoint that the effect of improving the adhesiveness and the like can be more exerted, and particularly preferably 1 to 1000 mg / m ² .

As shown in Fig. 2, the containers and caps are manufactured as follows.
Printing or resin coating is applied to the aluminum material as described above to form a printing layer (3) or a coating layer (4), which is then baked and then stretch-molded into a predetermined shape. Vinyl-based and epoxy-based resins are generally used as the coating resin. The size coat is no longer necessary for this printing or resin coating.

Effects of the Invention As described above, the present invention, as an undercoat for printing or resin coating on the surface of an aluminum substrate, a polyacrylamide resin film containing a metal compound, the adhesion amount of the metal compound 0.1mg / m It is characterized in that it is formed into a coating in a state defined by ² or more, and that the undercoat is printed or resin-coated and is stretch-molded. As is clear from the examples, even if the size coat is omitted and the film surface is directly printed or resin-coated, it can maintain excellent adhesiveness with resin and printing ink and is stable against heat. As a matter of course, peeling of printing ink and coating film does not occur during expansion molding processing on containers and caps, and coating film does not peel off even during retort sterilization treatment. . Further, the corrosion resistance of the coating is excellent, and it is possible to prevent a situation in which the coating is corroded by the contents of the container during storage for a long period of time and further the aluminum substrate is corroded, and by extension, the corrosion resistance of the container or the cap can be improved. Furthermore, since the film can be formed by applying the treatment liquid, not only the workability is good, but also the treatment cost is low because the treatment liquid is a water-soluble treatment liquid, and the waste liquid treatment of the treatment liquid is unnecessary. There is also such an effect.

Embodiment Next, an embodiment of the present invention will be described.

A plurality of 0.23 mm thick aluminum base materials (tempered H34) made of JIS1100 and 1200 alloys were prepared, and the surfaces of these base materials were first degreased with a surfactant, followed by washing with water and drying in sequence. Then, various aluminum materials shown below were manufactured for each set of aluminum base materials.

Example 1 First, a solution (A) containing ammonium zirconium carbonate and a polyacrylamide resin having the following properties.
Prepared.

Properties of solution (A) PH: 8.1 (at 25 ° C) Viscosity: 23cP (at 27 ° C) Ammonium zirconium carbonate amount: (0.3 for zirconium
%) Polyacrylamide resin amount: 5% Then, the above solution (A) was mixed at a ratio of 1 and water to prepare a treatment liquid. Then, this treatment liquid is applied to the surface of an aluminum base material with a rubber roll, and then dried at 200 ° C. for 20 seconds to obtain an aluminum material according to the present invention having a polyacrylamide resin film containing a zirconium compound on the surface. It was At this time, the coating amount was 100 mg / m ² and the amount of ammonium zirconium carbonate attached was about 5 mg / m ² .

Example 2 A solution containing a zirconium fluoride compound and a polyacrylamide resin (B) and a solution containing a chromium fluoride compound (C) having the following properties were prepared.

Properties of solution (B) PH: 5.2 (at 25 ° C) Viscosity: 16 cP (at 27 ° C) Specific gravity: 1.025 (at 27 ° C) Molecular weight: 50,000-100,000 Zirconium fluoride amount: (0.5% zirconium) Polyacrylamide resin Amount: 5% Properties of solution (C) Chromium amount: 0.83% F concentration: 0.9% Then, solution (B) is mixed at a ratio of 5, solution (C) at a ratio of 1 and water to make a treatment liquid, After applying the treatment liquid on the surface of an aluminum substrate with a rubber roll, drying at 200 ° C. for 20 seconds is performed, and the aluminum material according to the present invention having a polyacrylamide resin film containing a zirconium compound and a chromium compound on the surface. Got The coating amount at this time was 60 mg / m ² . The amount of zirconium compound attached was 5 mg / m ² , and the amount of chromium compound attached was 2 mg / m ² .

[Comparative Example 1] A conventional aluminum material was obtained by forming a phosphoric acid-chromate film on the surface of an aluminum substrate by a known method. The amount of deposited chromium was about 10 mg / m ² .

[Comparative Example 2] The above-mentioned rolled aluminum base material not subjected to the surface treatment and film treatment was used as it was as an aluminum material.

The following tests were performed on the four types of aluminum materials obtained as described above.

[Adhesion Test of Resin Coating and Printing Ink] A black acrylic resin was coated on the surface of each aluminum material to a thickness of about 10 μm, and dried at 200 ° C. for 10 minutes to form a coating. Similarly, the surface of each aluminum material was printed with an ink made of a black alkyd resin and dried at 150 ° C. for 10 minutes to form a printed layer having a thickness of about 2 μm. Then, each test material was subjected to bulging molding processing using an Erichsen tester based on JIS B7729, and the peeling state of the coating film and printing ink in the molding part was visually observed (1
Next adhesion test). Furthermore, the one subjected to bulging molding processing by the above Erichsen tester was subjected to hot water treatment at 95 ° C or higher.
After soaking for 30 minutes, the peeling state of the coating film and the printing ink on the molded part was also visually observed (secondary adhesion test). The results are as follows: ○: No peeling was observed, △:
The results are shown in Table 1 as those in which fine peeling was observed, x: The degree of peeling was severe.

[Corrosion Resistance Test] The above four kinds of aluminum materials were visually observed for the corrosion state of the surface when salt spray according to JIS Z2371 was applied for 150 hours. The results are shown in Table 1 as ◯: no corrosion was observed, Δ: slight corrosion was observed, and x: severe corrosion was observed. Moreover, the discolored state of the surface of each aluminum material when immersed in hot water at 95 ° C. or higher for 30 minutes was visually observed. The results are shown in Table 1 as ◯: no discoloration was observed, Δ: slight discoloration was recognized, and x: severe discoloration.

As is clear from the above results, the aluminum material according to the present invention is not limited to the one not subjected to the undercoating treatment, but also to the coating film, the printing, even if the undercoating film is a phosphoric acid-chromate film. It can be seen that the adhesiveness of the ink is excellent, the coating film and the ink are not peeled off during the bulging process, and the corrosion resistance of the film itself is excellent.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an aluminum material according to the present invention, and FIG. 2 is an enlarged sectional view of a state in which a coating layer or a printing layer is formed on the aluminum material of FIG. (1) ... Aluminum base material, (2) ... Polyacrylamide resin film, (3) ... Printing layer, (4) ... Coating film layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-60-221582 (JP, A) JP-A-51-82324 (JP, A) JP-A-63-171683 (JP, A) JP-A-62- 87286 (JP, A)

Claims (3)

[Claims] 1. A polyacrylamide resin coating containing one or more metal compounds as an undercoat for printing or resin coating on the surface of an aluminum substrate, wherein the metal compound (two or more metal compounds are used). When it is contained, at least one of them is coated to form a coating amount of 0.1 mg / m ² or more, and the base film is printed or resin-coated and stretch-molded. An aluminum material that does not peel off the printing ink or resin coating film during bulging, which is characterized by being made. 2. An aluminum material having no peeling of printing ink or resin coating film during bulging molding according to claim 1, wherein the metal compound contained in the polyacrylamide resin film is a zirconium compound. 3. An aluminum material which does not peel off the printing ink or resin coating film during bulging molding according to claim 1, wherein the metal compound contained in the polyacrylamide resin film is a zirconium compound and a chromium compound.