JPH03257146A - Manufacturing method of aluminum foil for resin laminate - 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 Field of Industrial Application This invention relates to a method for producing aluminum foil for resin lamination used, for example, in aluminum containers for food packaging;
In particular, the present invention relates to a method for producing aluminum foil that has excellent adhesion to resin and corrosion resistance.

In this invention, the term aluminum is used to include its alloys.

BACKGROUND OF THE INVENTION Aluminum foils for resin lamination used in aluminum containers for food packaging and the like are required to have good adhesion between the resin and the aluminum foil and sufficient corrosion resistance for packaged foods.

Such adhesion and corrosion resistance are not only affected by the surface condition of the aluminum foil, such as the presence or absence of an oxide film or oil film, but also greatly affected by Mg as an impurity that is concentrated on the surface when the aluminum foil is annealed. It is known that as the surface concentration of Mg increases, adhesiveness and corrosion resistance decrease.

Therefore, in order to obtain good adhesion and corrosion resistance, the annealing temperature is set low to prevent Mg contained in the aluminum foil from concentrating on the surface during annealing.
Alternatively, instead of annealing according to a conventional method, an aluminum foil whose Mg content is regulated to, for example, about 30 ppm or less is used as the foil material.

Problems to be Solved by the Invention However, when annealing is performed at a low temperature, there is a problem in that the moldability after resin bonding deteriorates.

On the other hand, when aluminum foil with Mg content controlled to 30 ppm or less is used as the foil material, there is a problem in that the cost is high because the alloy is expensive.

This invention was made in view of the above-mentioned problems, and it is possible to produce an aluminum foil for resin lamination that has excellent adhesiveness and corrosion resistance without using aluminum foil with a particularly low Mg content as a foil material. This was done to present a method.

Means for Solving the Problem In order to distantly achieve this object, the inventor conducted various experiments and research, and found that the Mg content could be significantly reduced by annealing the aluminum foil in an atmosphere with low moisture content. The present invention was completed based on the discovery that excellent resin adhesion and corrosion resistance can be obtained even if the aluminum foil is not controlled.

In other words, this invention uses M as an impurity as a foil material.
Using an aluminum foil with an allowable g content of 300 ppm or less, the aluminum foil has a water content of 50
The gist of the present invention is a method for producing aluminum foil for resin lamination, which is characterized by annealing in an atmosphere regulated to 0 ppm or less.

As an aluminum foil material, Mg content as an impurity is allowed up to 30ppm.

This is because if a foil material containing more than 300 pprn of Mg is used, even in the present invention, the foil material will lack adhesiveness to resin and corrosion resistance to packaged foods.

However, from this point of view, it is preferable to use a material with as low a Mg content as possible, but using a material with an extremely low Mg content increases costs as the foil material becomes expensive. I will invite you.

Therefore, a range of about 5 to 1100 pp is preferably used. The remaining composition other than Mg is not particularly limited. Therefore, for example, it may be pure A2 (IN30, etc.), or may be an A3003 alloy or an Aj;j-Fe series alloy.

As described above, an aluminum foil material having a Mg content as an impurity of a predetermined value or less is annealed in an atmosphere in which the water content is regulated to be 5 oppm or less.

Since the moisture content is extremely high in normal air atmosphere and it is difficult to control it, it is preferably carried out in an inert gas atmosphere such as nitrogen gas or argon gas, or in a vacuum atmosphere. The reason for regulating the moisture content as described above is that, although the mechanism is not necessarily clear, when the moisture content in the atmosphere decreases, it becomes difficult for Mg to concentrate on the surface of the aluminum foil. This is because if the content exceeds 500 ppm, the effect of inhibiting Mg concentration will be poor. A particularly preferred water content is 1100 pp or less.

Annealing temperature is about 200-500℃, annealing time is 2-15
About an hour is desirable. This is because if the annealing temperature is less than 200°C, sufficient annealing cannot be performed, whereas if it exceeds 500°C, surface concentration of Mg will be promoted. In addition, if the annealing time is less than 2 hours, sufficient annealing cannot be performed, and conversely, if the annealing time is less than 2 hours,
This is because if the time is exceeded, Mg will be concentrated on the surface. A particularly suitable annealing temperature is 250 to 400°C, and a suitable annealing time is 3 to 10 hours.

The aluminum foil annealed in this way is used with a synthetic resin film laminated on its surface, and examples of such films include polypropylene (pp), polyester (PET), Examples include polyethylene (PE) and nylon.

Effects of the Invention As described above, the method for producing aluminum foil for resin lamination according to the present invention uses an aluminum alloy foil having an allowable Mg content as an impurity of 300 ppm or less as a foil material. The material cost is lower than when using aluminum foil whose content is regulated to a very low value.

In addition, the above aluminum foil has a water content of 500 ppm.
Since the annealing is carried out in an atmosphere regulated as follows, surface concentration of Mg is suppressed, resulting in excellent adhesiveness and corrosion resistance. Moreover, since the annealing does not need to be carried out at a lower annealing temperature as in the conventional case, it is possible to eliminate problems such as poor moldability after resin bonding.

Example Next, examples of the present invention will be shown in comparison with comparative examples.

Margin below c] Table 1! Various foil materials having a thickness of 30 μm made of A3003 alloy with the Mg content shown in Table J1 were prepared, and these were heat annealed at 380"C for 13 hours in the atmosphere shown in the same table.

The surface Mg concentration of the aluminum foil after annealing was measured using a fluorescent X-ray analyzer, and the results are shown in Table 2.

Next, a vinyl chloride resin coating layer was formed on the surface of each of the aluminum foils, and the adhesive strength was measured.

Further, the coating layer was cut into a cross shape with a knife, subjected to a salt spray test for 1000 hours in accordance with Jl522371, and then the state of occurrence of corrosion was visually determined.

As a result, those in which corrosion progressed from the cross-cut portion are marked x5, and those in which corrosion did not progress are marked with ○ in the same table.

[Margins below] Table 2 As is clear from the above results, it was confirmed that according to the present invention, it was possible to obtain an aluminum foil for resin bonding with excellent adhesiveness and corrosion resistance.

that's all

Claims (1)

[Claims] Mg content as an impurity as a foil material is 300ppm
A method for producing an aluminum foil for resin laminate, which comprises using an aluminum foil that is acceptable within the following range, and annealing the aluminum foil in an atmosphere where the moisture content is regulated to 500 ppm or less.