JPS627541A - Aluminum laminate material for cap seal - 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 an aluminum laminate material for a cap seal for producing a cap seal with less elastic deformation (so-called springback) after molding.

In this specification, the term "aluminum" is used to include aluminum alloys.

Conventional technology Soft foil (so-called O material) made by annealing 1N30 alloy, etc. has been used as a material for cap seals of food and drink containers, etc., but such soft foil has low strength, so foil The thickness must be relatively thick, approximately 30 to 100 μm, and it has become impossible to meet recent demands for cost reduction.

Therefore, recently, aluminum laminate material, which is made by laminating a synthetic resin film on aluminum foil, has been used as a cap seal material to reduce the cost by thinning the aluminum foil itself and to compensate for the decrease in strength due to the thinning of the foil. It's starting to look like this.

Problems to be Solved by the Invention However, in such aluminum laminate materials, since the elastic modulus of the synthetic resin film is low, the springback of the laminate material after drawing is generally large, and the shape of the drawing punch is even worse. This has led to drawbacks such as the possibility that the resulting product is different and may cause processing problems in the next step.

This invention was made in view of such circumstances, and
The object of the present invention is to provide an aluminum laminate material that can reduce springback of a cap seal after drawing.

Means for Solving the Problem In order to achieve this objective, the inventor conducted various experiments and research and determined the amount of elastic recovery after 1% deformation due to tensile deformation of aluminum laminate material and the springback after forming. There is a close relationship between the stress and the elasticity, especially when the ratio of the stress (σ1.0) at 1% deformation due to tensile deformation of the laminate material and the apparent elastic modulus (E) is 0.003 or less. In some cases, I found that the above purpose could be effectively achieved, and after extensive research, I found that these conditions were the same as the thickness and tensile strength of the aluminum foil forming the aluminum laminate, and the thickness and 1% elongation of the synthetic resin film. The present invention was completed by discovering that this can be satisfied by keeping the tensile stress within a certain range.

That is, this invention has a thickness of 10 to 25 μm and a tensile strength of 7 to 25 μm.
A synthetic resin film with a thickness of 4 to 30 μm and a tensile stress of 0.5 to 3 kgr/IWA at 1% elongation is laminated on at least one side of an aluminum foil of 16 kgf/mtA, and is deformed by 1% due to tensile deformation. A cap characterized in that the ratio σ1°o/E of the stress (σt,o) kOf/− and the apparent elastic modulus (E)kaf/− is 0.003 or less. This article focuses on aluminum laminate materials for seals.

Stress at 1% deformation of aluminum laminate material (σ1.
0>, the apparent elastic modulus (E) can be easily determined from a stress-strain curve based on tensile deformation, as is well known.

If the tensile strength of aluminum foil or the tensile stress of a synthetic resin film at 1% elongation is less than the lower limit of the above range, the breaking strength will not be satisfied, and if it exceeds the upper limit, the aluminum laminate material will eventually deform by 1%. The stress at time (σ
1. O) and the apparent elastic modulus (E) is the ratio σ1. o/
E exceeds 0°003, the amount of springback of the cap seal becomes large, and the intended purpose of the invention cannot be achieved. The tensile strength of the aluminum foil is preferably around 10 kgf/mm2. Further, if the thickness of the aluminum foil is less than 10 μm, the breaking strength is too low, and if this is compensated for by the film, the thickness of the film becomes thicker, the strength becomes higher, and the amount of springback increases. That is,
It is not possible to manufacture a material that satisfies σ1.0/E≦0.003 and has satisfactory breaking strength. On the other hand, if the thickness exceeds 25 μm, there will be a drawback that the cost will increase, so it is preferable to set the thickness to 20 μm or less. The aluminum foil has the above thickness,
The material can be of any type as long as it satisfies the tensile strength, but an example is a soft part obtained by treating a pure aluminum alloy such as 1N30 alloy with O material. On the other hand, if the thickness of the synthetic resin film is less than 4 μm, and 30 LITr
If it exceeds L, the disadvantage of a significant increase in cost will also arise. Examples of synthetic resin films include films of polypropylene, polyester, polyethylene, nylon, and the like. The thickness and tensile stress of the film may be within the above range, but it is generally desirable to set the thickness to about 4 to 9 μm for a polyester film and about 5 to 15 μm for a stretched polypropylene film. Furthermore, as an example of the tensile stress of a synthetic resin or resin film in a state of 1% elongation, in the case of polyester (thickness 6 μm or 9 μm), 12 kaf/ali
and of /- in the case of polypropylene stretched film (thickness 5 μm).
・Aluminum laminate material is formed by laminating the above aluminum and synthetic resin film.
.

However, this invention applies to aluminum foil with a resin film laminated only on one side, aluminum foil with the same kind of film laminated on both sides, aluminum foil with a different type of film on each side, or Furthermore, the same kind on the film,
Allows for lamination of multiple layers of different types of films. In this case, for aluminum laminate materials in which two or more synthetic resin films are used on one or both sides of aluminum foil, the thickness of each film alone, 1
The total value of the tensile stress in the % elongated state is 0.0000000000 when the film thickness is 4 to 30 μm and the tensile stress in the 1% elongated state is 0.
If it satisfies the condition of 5 to 13 kgf/mm2, springback can be reduced. The stress due to tensile deformation of the aluminum laminate material was defined at 1% deformation because the actual forming process for cap seals does not cause large deformation, and it is just based on the stress value and elastic modulus at 1% tensile deformation. This is because the determined springback amount of the aluminum laminate material itself corresponds well to the springback amount of the cap seal after molding. Therefore, σ1 at 1% deformation. The most desirable material is a material with o/E of 05OO3 or less and high breaking strength.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, as described in detail, by laminating an aluminum foil and a synthetic resin film whose thickness and tensile strength or tensile stress at 1% elongation are within a predetermined range, The stress at 1% deformation due to tensile deformation and the apparent elastic modulus are the ratio σ1. It is possible to produce an aluminum laminate material for cap seals with an o/E of 0.003 or less, and by drawing this aluminum laminate material, springback can be reduced, as will be clear from consideration of the examples described below. We can provide a cap seal with a

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

As shown in Table 1, various aluminum foils and synthetic resin films with different materials, thicknesses, tensile strengths, and tensile stress at 1% elongation (indicated by σ in the table) were prepared, and one side of the aluminum foil was Two-layer aluminum laminate material laminated with resin film (1) (sample No. 1.3 to 11)
) and a resin film (1) on one side of the aluminum foil.
An aluminum laminate material (sample No. 2) having a three-layer structure in which a resin film (2) was laminated on the other side was produced. In addition, among the materials of synthetic resin film in Table 1, OPP
is polypropylene stretched film, CPP is polypropylene cast film, PET is polyester film,
PE stands for polyethylene film.

[Left below] Then, each aluminum laminate material was subjected to a tensile test, and the rupture force and apparent elastic modulus at 1% deformation due to tensile deformation were determined. A cap seal was manufactured by shallow drawing under the above conditions, and the stress at 1% deformation and the apparent elastic modulus were υ
σ1. The relationship between o/E and the amount of spring deflection of the cap seal was investigated. The spring knock amount was evaluated based on the difference between the maximum diameter of the cap seal and the punch C. The results are shown in Table 2.

[Margins below] ; Table 2; >; As is clear from the above results, the aluminum laminate materials according to the present invention all have a ratio of stress at 1% deformation due to tensile deformation to the apparent elastic modulus σ1 .0/E is 0.0
03 or less, and it was confirmed that the springback of the cap seal after molding was the least.

that's all

Claims (1)

[Claims] Thickness 10~25μm, tensile strength 7~16kgf/mm^
At least one side of the aluminum foil of No. 2 has a thickness of 4 to 30
μm, tensile stress at 1% elongation 0.5 to 13 kg
f/mm^2 synthetic resin films are laminated and bonded, and the stress at 1% deformation due to tensile deformation (σ_1_._0) kg
f/mm^2 and apparent elastic modulus (E) kgf/mm
Ratio of ^2 σ_1_. An aluminum laminate material for a cap seal, characterized in that _0/E is formed to be 0.003 or less.