JPS61209149A - Composite plate for can end - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to can container materials for fruit juices such as tomato and orange, and soft drinks containing mounds, particularly aluminum composite plates suitable as can end materials. .

(Prior Art) Conventionally, all-steel so-called three-piece cans have been widely used as can containers for the above-mentioned contents.

This is a steel end (1) as shown in Figure 2.
, a body (2), a bottom (3), etc.

However, regarding M (can end), the ease of various processes that must be performed on the surface of the lid (riveting for attaching the easy-open tab, scoring process, etc.), the ease of opening, and the shape of the opening cut. For reasons such as safety, it is desirable to use aluminum plates instead of steel plates.

For carbonated drinks such as beer, less corrosive juices, coffee, etc., use a steel body.

As a can end material, JIS 5052 (A-2.2
~2.8% by weight [Hereinafter, weight% is simply expressed as %] M g
-0.15~0.35%Cr alloy), 5082 (Al
l-4, 0~5.0% Mg alloy), 5182 (Al-4
, 0 to 5.0% M g -0, 20 to 0.50 M n alloy) and the like are used.

Conventional aluminum materials cannot be used for contents that contain relatively high amounts of salt, such as tomato juice, sports drinks, and soups, because pitting occurs easily at the end of the can due to contact corrosion due to the steel body. .

Therefore, steel plates have often been used as can end materials, but in recent years aluminum alloy plates have been used as core materials.
(Cu, Mn, Mg) alloy, and the use of a composite plate made of A11-Zn alloy as a skin material as a can end for these highly corrosive contents has been proposed (Japanese Patent Laid-Open No. 52-8388). issue).

(Problems to be Solved by the Invention) However, this aluminum alloy composite plate is still not satisfactory in terms of corrosion patterns.In other words, this composite material is clad with Al-Zn alloy, so it does not suffer from deep pitting corrosion. Although this can be prevented from occurring, there is a problem in that the resin film partially lifts up. Aluminum can end materials are generally used after being coated with a resin film.

However, if there are defects in the resin film or scratches caused by easy-open tab attachment, score processing, etc., the aluminum plate at the end of the can can cause contact corrosion against the steel material of the can body through the contents of the can container. However, as the corrosion progresses and the corroded area expands, the resin film becomes partially lifted. At this time, if the potential difference between the skin material and the core material is large, the skin material will be corroded excessively and the corrosion will spread in the lateral direction, causing the resin film to rise widely.

The purpose of the present invention is to obtain a composite plate for can end materials that has the strength and formability required for can end materials, prevents the expansion of the corroded area of the cladding layer, and prevents deep pitting from occurring. It is in.

(Means for Solving the Problems) That is, the present invention has the following features: 1) A core material of an aluminum alloy containing 0.5 to 560% Mg and the remainder being Al, with 0.2 to 5.0% Mg and Z
Composite plate for can ends characterized by being formed by cladding an aluminum alloy containing V containing n0.2 to 2.0% and the balance being Al (hereinafter referred to as the first invention) and 2) Mg 0.5 to 2. 5.0% cr 0.05~
0.5%, Cu0.1-2.0%, Mn 0.1-1.
A core material of an aluminum alloy containing one or more of 5% and the balance being Al, containing 0.2 to 5.0% Mg and 0.2 to 2.0% Zn, and the balance being Al. The present invention provides a composite plate for can ends (hereinafter referred to as the second invention) characterized by being made of a certain aluminum alloy clad.

The reasons for limiting each component in the aluminum alloy of the core material and cladding layer in the composite plate of the present invention are as follows.

In both the first and second inventions, Mg in the core material improves the strength of the can end material. If this amount is less than 0.5%, the effect is insufficient, and if it exceeds 5.0%, moldability deteriorates.

Further, in the second invention, Cr0.05 to 0.5% is contained in the core material.
, Cu 0.1 to 2.0%, and Mn 0.1 to 1.5%. These components further improve the strength of the core material and make the core material more electrochemically effective than the skin material, so they are used when higher strength and sacrificial anode effect are required. Contains. The content is less than 0.05% Cr, Cu
If the content is less than 0.1% and Mn0 is less than 51%, the desired effect of improving the above action cannot be obtained, while 0.5% Cr, C, u 2
% and Mn exceeding 1.5%, moldability deteriorates and the effect of inducing potential becomes saturated.

Next, in both the first invention and the second invention, Mg is present in the cladding layer.
Contains 0.2 to 5.0%. If the Mg content is less than 0.2%, the strength will be insufficient, and if it exceeds 5.0%, the moldability will deteriorate. Furthermore, the addition of Mg has the effect of improving corrosion resistance and suppressing partial lifting of the resin film. It also makes the potential of the cladding layer less noble, contributing to improved pitting corrosion resistance.

Further, in both the first invention and the second invention, 0.2 to 2.0% of Zn is contained in the rad layer.

Zn has the effect of lowering the potential of the skin material, and if it is less than 0.2%, the effect will not increase, and if it exceeds 2.0%, the effect will be saturated.

The composite plate of the present invention can be manufactured according to conventional methods. Generally, it is preferable to form a can end by laminating a resin on the surface of the cladding layer obtained in this way by thermocompression bonding or by applying a paint such as epoxy resin or vinyl resin. It may be used as is without coating, but when coating with a resin film, it is preferable to apply a chemical conversion film such as chromium in advance.

In the present invention, the cladding ratio of the skin material to the core material is not particularly limited, but is usually 2 to 20%, preferably 5 to 15%.
is within the range of The thickness of the resin film is preferably 4 to 2
The range is 0 pm, but is not limited thereto.

Further, in the present invention, the cladding layer is provided on one or both sides of the core material.

The aluminum composite plate of the present invention can be used as a can end with any kind of plastic body material, but is particularly suitable for use when the plastic body material is a steel plate. The case where the can container is made into a can container in this way is shown in the enlarged view of the main part in FIG.
(7a) is a core material, (7b) is a cladding layer, and (7c) is a resin film. In addition, (8) is a score (scorched line) formed on the can end, and (9) is a can body made of a tin-free steel plate (9a) coated with resin (9C).

(Example) Next, the present invention will be explained in more detail based on examples.

As an example core material, an alloy having the composition shown in Table 1 was cast, and then soaked and surfaced in a conventional manner to produce a core material. On the other hand, the skin material was manufactured by casting an alloy having the composition shown in Table 1, soaking and face cutting in a conventional manner, and then heating and rolling it. The skin material was placed on one side of the core material obtained in this way, heated in a conventional manner, and then hot rolled.

Subsequently, cold rolling, intermediate annealing, and cold rolling were performed to obtain a 0.3
An aluminum composite plate with a thickness of m (cladding thickness of 0.03 m layer) was manufactured.

This aluminum composite plate was annealed at a low temperature to obtain a plate with heat quality H38. This board was treated with a chemical conversion coating using a phosphoric acid/chromic acid mixture, and then an epoxy resin coating was applied evenly for 10J.
It was applied to a thickness of Lm.

〔Test method〕

Each sample of the aluminum composite plate obtained as described above and the steel plate were engaged by bending their edges, and then caulked and fixed to electrically connect the aluminum composite plate and the steel plate. Furthermore, a scratch was made at the X portion on the film of the aluminum composite plate sample using a knife.

The thus prepared sample was immersed in 3% saline for 3 months, and the corrosion form was evaluated based on the corrosion of the X part (corrosion distance from the X part).

The pitting depth of the aluminum composite plate is 1 OpHll.
Measurements were made by immersing the sample in tap water to which 1 of Cu''t had been added for 4 weeks.

Further, the potential difference between the core material and the skin material was determined by measuring the potential with respect to a saturated red electrode in 3% saline solution and determining the difference.

The results of these tests are shown in Table 1.

In addition, as a conventional material, Al-1,0%Mg-0,9%Cu
Composite plates made of -0.4% Mn alloy as core material and Al-018% Zn alloy cladding and bare materials of JIS5052.5082 and 5182 were similarly tested.
The results are also shown in Table 1.

The evaluation criteria for each test are as follows.

(IIL) Corrosion form: 2I■ from part X or less Corrosion 2■ from 0x mark
Corrosion exceeding 5 mm or less Corrosion exceeding 5a snow from the Δ× mark As such, the aluminum composite plate of the present invention has a potential of the cladding layer that is about 50 mV or more more base than the potential of the core material, and does not form deep pitting against salt-containing contents when in contact with the steel plate. Even if corrosion occurs from a scratched location, the corrosion area of the cladding layer is small and the resin film will not peel off.Furthermore, the core material of the aluminum composite plate of the present invention is made of aluminum alloys commonly used at present. The composition is close to that of can end materials, and there are no problems in strength and workability.Furthermore, when the core material contains Cu and Mn in the aluminum composite plate of the present invention, the potential difference between the core material and the cladding layer increases, causing damage to the resin film. , the depth of pitting corrosion caused by defects can be suppressed to less than the thickness of the cladding layer.

As described above, the aluminum composite plate of the present invention is extremely useful as a can end material for can containers having contents with relatively high salt concentration.

[Brief explanation of the drawing]

FIG. 1 is an enlarged vertical cross-sectional view of the main parts of a three-piece can using the composite plate for can ends of the present invention, and FIG. 2 is a vertical cross-sectional view of a typical three-piece can.

Claims (2)

[Claims] (1) A core material of an aluminum alloy containing 0.5 to 5.0% Mg and the balance being Al, containing 0.2 to 5.0% Mg and 0.2 to 2.0% Zn, the balance being Al. A composite plate for can ends, characterized in that it is clad with an aluminum alloy that is Al (the above weight %). (2) Mg0.5-5.0% and Cr0.05-0.5%
, Cu0.1~2.0%, Mn0.1~1.5%, and the remainder is Al. .2~2
．． 1. A composite plate for can ends, characterized in that it is clad with an aluminum alloy containing 0% Al and the remainder being Al (the above weight %).