JP2643785B2 - Metal container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal container ,
Laminated film based on high-frequency welded aluminum foil layer
Seals the opening and preserves the contents for a long time
The present invention relates to a metal container capable of performing the following .

[0002]

2. Description of the Related Art In general, the opening of a metal container filled with hand cream or the like is sealed with a laminated film based on an aluminum foil layer in order to prevent deterioration of the quality of the contents. As one of the methods, there is a method of welding the laminated film to the opening edge of the metal container by high-frequency induction heating.

[0003] In the case of sealing by the above-mentioned welding, a laminated film in which a high-frequency welding layer is laminated on one side of an aluminum foil layer is used as the laminated film, and the high-frequency welding layer side of the laminated film is connected to an opening edge of a metal container. The laminated film is welded to the opening edge through the high-frequency welding layer by being heated by a high-frequency induction heating method.

The high-frequency induction heating method is an internal heating method, and has an advantage that a required amount of heat can be obtained in a short time because the welded portion is directly heated. Therefore, the effect of heat on the contents is relatively small.

Conventionally, the high frequency welding layer is disclosed in
Thermoplastic resins having a polar group in the molecule, such as EVA (ethylene-vinyl acetate copolymer) and EAA (ethylene-acrylic acid copolymer) described in JP-A-93451 are used. However, these thermoplastic resins have few polar groups in the molecule, and therefore have poor adhesion to a metal container, so that these thermoplastic resins cannot be directly welded to the metal container.

Therefore, in order to improve the adhesiveness of the thermoplastic resin, a method of previously baking and coating a thermosetting resin having a good affinity with the thermoplastic resin on the bonding portion (the opening edge portion) of the metal container has been proposed. In order to stabilize the adhesive force due to the welding of the thermoplastic resin, the bonding portion of the metal container is flattened in advance, or the diameter of the bead is increased at the time of bead processing of the opening edge portion, and the bonding portion is formed. For example, there is a method of increasing the area of the device.

[0007]

However, even if the thermosetting resin is baked and coated on a metal container, it is still necessary to perform welding at a high temperature for a long time in order to obtain sufficient adhesiveness. Therefore, when the content of the metal container is sensitive to heat, for example, a hand cream, the components of the content may be separated or the appearance may change during the welding. Also, if the welding temperature is kept low considering the effect of heat on the contents,
There is a problem that welding is incomplete and sufficient sealing performance cannot be obtained.

In addition, there is a problem in that a large amount of labor and cost are required to process the opening edge of the metal container to increase the area of the bonding portion.

The thermoplastic resin constituting the high-frequency welding layer is usually laminated on the aluminum foil layer by extrusion lamination. When extruding and laminating a thermoplastic resin on a polar surface such as aluminum foil, both of them are used. In order to improve the adhesive strength of aluminum foil, the surface of the aluminum foil is coated in advance with a highly polar plastic to improve the surface of the aluminum foil. Further, in order to make the plastic highly polar, a corona discharge treatment or a flame treatment is performed on the surface of the plastic to express a polar group on the surface.

However, when the thermoplastic resin is a polyester-based hot melt, the polyester-based hot-melt layer is coated with a highly polar plastic on the surface of the aluminum foil, and then the polyester-based hot-melt layer is coated with a metal. Polar solvent (water, etc.) in the container
When the contact is made, the adhesive strength between the aluminum foil layer and the polyester-based hot melt layer is still insufficient, so that the polyester-based hot melt layer swells due to contact with the polar solvent in the metal container. If it is stretched out, it may be peeled off from the aluminum foil layer.

Accordingly, it is an object of the present invention to seal an opening.
That film when RF welding, it is not necessary to perform processing for a wider area of the bonding portion of the metal container, and the
Even if the film is subjected to high-frequency welding at a temperature at which the content of the metal container does not change, it is possible to obtain a strong seal strength and sealing property, and further, the high-frequency welding layer contacts the polar solvent in the metal container. and even swelled, in that said film provides a possibility no metal container which peeled off from the aluminum foil layer.

[0012]

The present inventors have conducted various studies on various thermoplastic resins to be used as a high-frequency welding layer. As a result, the conventional thermoplastic resins have a high melting point and a polar group in the molecule. Focusing on the fact that the number of the high-frequency welding layer is small, a thermoplastic resin having a low melting point and a large number of polar groups in the molecule is used as the high-frequency welding layer, and a suitable intermediate layer is provided between the high-frequency welding layer and the aluminum foil layer. It has been found that the above object can be achieved by laminating layers.

The present invention has been made on the basis of the above-mentioned findings, and a film in which at least a high-frequency welding layer is laminated on an aluminum foil layer is welded to an opening of a metal container through the high-frequency welding layer by a high-frequency induction heating method. In the metal container in which the opening is sealed, the film is a film in which a polyester-based hot melt layer having the following composition is laminated as the high-frequency welding layer on the aluminum foil layer via a polyethylene terephthalate layer. It is intended to provide a metal container characterized by the following.

[0014]

[Action] Oite the metal container of the present invention, in the high frequency welding layer, compared with the conventional thermoplastic resin, due to the use of polyester-based hot-melt number of polar groups are often in the molecule with a low melting point, the contents the fill <br/> beam on the order of temperature alteration does not occur by high-frequency welding to the open mouth, it is possible to obtain the sealability with strong seal strength.

Further, Oite the metal container of the present invention, the adhesive bond between the polyester-based hot-melt layer and the aluminum foil layer, the polyester-based hot-melt layer and the polyethylene terephthalate layer (hereinafter, PET layer That)
A first adhesive bond between the PET layer and the aluminum foil layer and a second adhesive bond between the PET layer and the aluminum foil layer, and the polyester-based hot melt layer in the first adhesive bond Since the adhesive strength between the polyester-based hot melt layer and the PET layer is very strong, even when the polyester-based hot melt layer swells and expands, there is no possibility that the polyester-based hot melt layer is peeled from the PET layer.

The polyethylene terephthalate (PET) in the second adhesive bond is less swellable than the polyester-based hot melt.
The T layer has no possibility of peeling from the aluminum foil layer. Accordingly, the polyester hot melt layer and the aluminum foil layer, which are adhesively bonded by the first and second adhesive bonding, do not have a possibility of peeling.

[0017]

THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the metal container of the present invention will be described with reference to the drawings. 1 is a sectional view showing a film in one embodiment of the metal <br/> container of the present invention, FIG. 2
Is a sectional view showing a state of welding to the opening of the metallic container at a high frequency induction heating method to indicate to full Irumu in FIG.

Film 1 in metal container 2 of the present embodiment
Is a laminated film in which a high-frequency welding layer 12 is laminated as a surface layer on one side of an aluminum foil layer 11 as shown in FIG.
By welding at a high frequency induction heating method of 該Fu Irumu 1 through the high frequency welding layer 12 in the opening edge portion 22 of the metal container 2, it is capable of sealing the open mouth portion 21.

[0019] In Thus, in the Fi <br/> Lum 1 metal container 2 of this embodiment, as shown in FIG. 1, the aluminum foil layer 1
1, a polyester hot melt layer is laminated as the high frequency welding layer 12 via a polyethylene terephthalate layer (hereinafter, referred to as a PET layer) 13.

The above-described fill in the metal container 2 of the present embodiment
1 , the thickness of the aluminum foil layer 11 is preferably 7 to 40 μm, more preferably 9 to 20 μm, and most preferably 12 to 20 μm.
１５15 μm. The thickness of the PET layer 13 is 5
To 40 μm, more preferably 9 to 2 μm.
0 μm, most preferably 12 μm. The polyester hot melt layer 12 has a thickness of 5 to 40 μm.
Is more preferable, more preferably 10 to 30 μm,
Most preferably, it is 20 μm.

The composition of the polyester hot melt constituting the polyester hot melt layer 12 is as follows :
Ru as Der below. The numerical values in parentheses indicate the composition good preferable. Dicarboxylic acid component; terephthalic acid 15-25 wt% (21-23 wt%), isophthalic acid 10-15 wt% (10-14 wt%), adipic acid 10-25 wt% (14-19 wt%), diol component: 1,4 butane Diol 50wt%

The physical properties of the polyester-based hot melt having the above composition are as follows. The numbers in parentheses are
It is a numerical value corresponding to a particularly preferred composition. Glass transition point -40 to -10C (-40 to -15C), melting point 78 to 130C (80 to 120C ), softening point 105 to 140C (110 to 131C).

Examples of commercially available polyester hot melts (thermoplastic low-melting polyester resins) having the above-mentioned components (composition) or physical properties include the following. Among the following commercially available products, Hardeck A5300, A6300, and Byron GM991
Are preferred, and above all, Hardeck A5300 and A630
0 is most preferred.

[Manufacturer name] [Product name] [Grade] Asahi Kasei Industries Hardeck A5300, A5400, A5410, A6300, A6400, A3200, A3300, A3410. Toyobo Byron GM400, GM460, GM900, GM991. Toray Chemit R-79, R-99, R-188, R-248.

Next, using the film 1 described above ,
The method of sealing the opening of the metal container (metal can such as an aluminum can) 2 of the present embodiment will be described. For example, as shown in FIG.
Covered with the film 1 taken more slightly larger size, so as Ategau high-frequency induction heating device 3 thereon.

The schematic structure of the high-frequency induction heating device shown in FIG. 2 will be described.
A rubber plate 32 is provided on the lower surface of the coil case 31 and the metal can 2
A copper tubular coil 34 is disposed via a copper plate 33 at a position almost directly above the opening edge portion 22 of the opening, and a ferrite 35 is provided upright on one side surface of the coil 34.

In the high-frequency induction heating apparatus 3, a high-frequency current is applied to the coil 34 so that the coil 3
4 to induce a high-frequency magnetic field around the high-frequency welding layer 12 located directly above the opening edge portion 22 of the metallic container sealing film 1 of the present embodiment and the induction heating, the film 1 to the high frequency welding layer 12 It can be welded to the opening edge 22 of the metal can 2 through the above.

The above as constituting metal container of this embodiment
Oite to 2, the high-frequency welding layer 12, due to the use of polyester-based hot-melt number of polar groups are often in the molecule with a low melting point compared with the conventional thermoplastic resin, the degree of temperature that deterioration does not occur in the contents in the film 1 by high-frequency welded into the opening 21 of the metal can 2, it is possible to obtain the sealability with strong seal strength.

According to the metal container 2 of the present embodiment ,
Serial film advance metal can 2 in baking is not necessary to paint the thermosetting resin affinity considering the 1, Therefore, the
Without considering the affinity with the full Irumu 1, by baking in advance in the metal can 2 by selecting a good thermosetting resin of the content resistance, further improve the film 1 of the adhesive (the weldability) It is also possible to make it.

Further , according to the metal container 2 of the present embodiment, the polyester hot melt of the high frequency welding layer 12 is
Since the metal can 2 is easily welded, it is not necessary to process the welded portion (opening edge 22) of the metal can 2 so as to increase its area.

In the metal container 2 of this embodiment,
Oite the film 1, the adhesive bond between the polyester-based hot-melt layer 12 and the aluminum foil layer 11, a first adhesive bond between the polyester-based hot-melt layer 12 and a polyethylene terephthalate layer 13, the The second adhesive bonding between the PET layer 13 and the aluminum foil layer 11 constitutes a two-step process, and the polyester hot melt layer 12 and the PET in the first adhesive bonding are used.
Since the adhesive strength with the layer 13 is very strong, even when the polyester-based hot-melt layer 12 swells and expands, the polyester-based hot-melt layer 12 remains
There is no risk of peeling from

Further, polyethylene terephthalate (PET) in the second adhesive bond is less likely to swell than a polyester-based hot melt.
The layer 13 does not have to be separated from the aluminum foil layer 11.

In short, the polyester-based hot melt layer 12 adhesively bonded to the aluminum foil layer 11 by the first and second adhesive bondings swells by contact with a polar solvent such as water in the metal can 2. Even if it is stretched, there is no risk of peeling from the aluminum foil layer 11,
Therefore, according to the metal container 2 of this embodiment, it is possible to save the contents of a long period of time to ensure the sealability have high Ri by the above fill <br/> beam 1.

Next, the above <br/> film 1 in the metal container 2 of this embodiment, for the awe Irumu such comprises the PET layer 13, the results of the test for peel strength of the polyester-based hot-melt layer explain.

In this test, an aluminum foil layer 11 having a thickness of 20 μm and a PET layer 13 having a thickness of 12 μm were laminated by dry lamination, and a 20 μm thick polyester hot melt was formed on the laminated film as a high frequency welding layer 12. The layers [Hardeck A5300 (trade name), manufactured by Asahi Kasei Kogyo] are laminated by extrusion lamination, and the total thickness is 52 μm.
The above-mentioned film 1 in the metal container 2 of Example 1 was prepared. The above configuration is schematically shown for easy understanding. (Outside) Aluminum foil layer (20 μm) / PET layer (12 μm)
m) / Polyester-based hot melt layer [Hardeck A5
300 (product name) 20 μm] (inside)

Further, as the awe <br/> Irumu such comprises the above PET layer 13, coated with a highly polar plastic surface of the aluminum foil layer having a thickness of 20 [mu] m, on its thickness as a high-frequency welding layer A polyester hot melt layer (Hardeck A5300 (trade name), manufactured by Asahi Kasei Kogyo Co., Ltd.) having a thickness of 20 μm was laminated by extrusion lamination to a total thickness of 40 μm.
m were prepared. The above configuration is schematically shown for easy understanding. (Outside) Aluminum foil layer (20 μm) / polyester hot melt layer [Hardeck A5300 (trade name) 20 μm
m] (inside)

[0037] The upper notated Irumu 1 and the PET layer 1
And provided with such awe Irumu a 3, O / W type openings 21, 21 opening 21, 21 are welded by high frequency induction heating method to each of the two metal cans 2, 2 cream was filled Was sealed and stored at room temperature for one month, and then opened to check whether the contents of each film had changed and to observe the inner surface of each film.

As a result, in both metal cans 2,
There was no change in the appearance of the contents (cream), and a strong seal was obtained in each case. In addition, the creams in the metal cans 2 and 2 all had only a very small amount of water transpiration, and no change in appearance, pH, stability of the contained medicinal agent, feeling of use, etc. was observed. .

Next, as a result of observing the inner surface of each of the films, no change was observed on the inner surface of the film 1 in the metal container 2 of this embodiment. This is because, in the film 1 of the metal container 2 of the present embodiment, the innermost layer of the polyester hot melt layer 12 has a low melting point and thus has slightly poor water resistance. By bonding to a PET layer 13 having a high melting point and a very high adhesive strength to the polyester hot melt, the swelling of the polyester hot melt layer 12 is suppressed only by the innermost layer, and P
By bonding the ET layer 13 to the aluminum foil layer 11, the peel strength of the polyester hot melt layer 12 can be strongly maintained by the adhesive bonding between the aluminum foil layer 11 and the PET layer 13. .

On the other hand, the above-mentioned PET layer 13 was not provided.
The inner surface of the awe Irumu, streaky partial peeling was observed. This is because in the awe Irumu such comprises the PET layer 13 swells by the inner layer of the polyester-based hot-melt layer is in contact with water, resulting elongation in the polyester-based hot-melt layer, this time the polyester-based hot Since the peel strength between the polyester hot-melt layer and the aluminum foil layer was too small with respect to the stress generated in the melt layer, the strip-like peeling occurred.

Accordingly, the metal container 2 of this embodiment is
From a metal container using a film without the ET layer 13
It can also be said that the storage stability (sealing property) of the contents is further excellent.

Next, a description will be given of a second embodiment of the metal container of the present invention. The metal container of this embodiment is shown in FIGS.
In the embodiment shown in FIG.
The only differences in the film are described below.
Will be described only. FIG. 3 shows a metal container according to the second embodiment.
That in cross-sectional view showing a film (FIG. 1 corresponding to view), the above-mentioned film 1A in the metal container of the second embodiment is different from the film 1 in the metal container 2 of the first embodiment,
In that the film 1A is formed by laminating a polyolefin, polyamide or polyester layer as an outer layer (a layer on the outer surface side after being welded to the metal container 2) 14 on the aluminum foil layer 11 of the film 1 described above. The film 1A in the metal container of Example 2 is the first film except for this point.
It is configured similarly to the above-mentioned film 1 in the embodiment.

The thickness of the outer layer (polyolefin, polyamide or polyester layer) 14 is preferably 5 to 40 μm, more preferably 9 to 20 μm, and most preferably 12 μm.

[0044] Also by the metal container of the second embodiment using the film 1A, the same effect as the first embodiment are achieved, also Oite the metal container of the second embodiment The above
Since the outer layer 14 is laminated on the outer surface side of the aluminum foil layer 11 of the film 1A, there is also an effect that the aluminum foil layer 11 is hardly damaged.

[0045] The present invention is not to say that not limited to the above embodiment, the upper notated Irumu is in the aluminum foil layer, via the polyethylene terephthalate layer, a polyester-based hot-melt as the high-frequency welding layer It is sufficient that the layers are stacked. For example, the film in the metal container of the present invention can be formed by laminating layers other than the polyethylene terephthalate layer, the high-frequency welding layer, and the outer layer on the aluminum foil layer. Any change can be made without departing from the spirit of the present invention.

[0046]

Effects of the Invention Metal containers of the present invention seals the opening
When the film is subjected to high frequency welding, it is not necessary to perform a process for increasing the area of the bonding portion of the metal container, and
Even if the film is high-frequency welded at a temperature at which the content of the metal container does not change, it is possible to obtain a strong seal strength and sealing property, and further, the high-frequency welding layer contacts the polar solvent in the metal container. be swell, there is no possibility that the film is peeled off from the aluminum foil layer.

[Brief description of the drawings]

FIG. 1 is off in an embodiment of the metal container of the present invention
It is sectional drawing which shows a film .

Figure 2 is a sectional view showing a state of welding to the opening of the metallic container at a high frequency induction heating method to indicate to full Irumu in FIG.

FIG. 3 is a sectional view (corresponding to FIG. 1) showing a film in the metal container of the second embodiment.

[Explanation of symbols]

1 Film 11 Aluminum Foil Layer 12 High Frequency Welding Layer 13 Polyethylene Terephthalate Layer 14 Outer Layer 2 Metal Container (Metal Can) 21 Opening 22 Opening Edge

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-58-166039 (JP, A) JP-A-55-78430 (JP, U) JP-A-57-136738 (JP, U)

Claims (2)

(57) [Claims] A metal container in which a film obtained by laminating at least a high-frequency welding layer on an aluminum foil layer is welded to an opening of a metal container through the high-frequency welding layer by a high-frequency induction heating method and the opening is sealed, the film, in the aluminum foil layer, via the polyethylene terephthalate layer, the following set as a high-frequency welding layer
A metal container characterized by being a film in which a formed polyester hot melt layer is laminated. 2. The metal container according to claim 1, wherein a polyolefin, polyamide or polyester layer is laminated as an outer layer on said aluminum foil layer.