JPS591197B2 - Laminated metal can and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminated metal can and a method for manufacturing the same.

Generally, the main material for metal cans, which are made up of three parts: top, bottom, and body, is tin plate or chromium-treated steel plate TFS.

Such tin plates and TFS metal cans have excellent resistance to internal corrosion, but corrosion is prevented by forming a protective film on the outer surface exposed to the atmosphere by painting, printing, etc. However, during the can making process, especially the seaming process, most of the protective film on the curled part is peeled off, so the metal surface is exposed and rust occurs, and the appearance may be damaged and the container may no longer function as a container. be. Moreover, when trying to prevent corrosion by painting, printing, etc., a protective film can hardly be expected to have any effect on the mechanical strength of the metal can itself, and solder or adhesives are not used separately to bond and seal the can body. is the current situation. The inventors of the present invention have carried out intensive research to provide a new metal can that eliminates the drawbacks of the conventional metal cans formed with a protective film. It was discovered that the desired metal can could be obtained by subjecting a laminated two-layer thermoplastic film layer and a large thermoplastic film layer to a can-making process and then heat-sealing it, and completed the present invention. I ended up letting it happen.

That is, the gist of the present invention is that the surface of the metal can has a bending rigidity of 0.
A thermoplastic film layer of 01×104 to 0.4×104 kg/ai and a bending rigidity of 0.5×1 on the film layer.
A laminated metal can characterized by providing a thermoplastic film layer of 04 to 3.0 x 104 kg/C77f, and a flexural rigidity of 0.01 x 104 to 0.4 x by laminating the surface of the metal plate. A thermoplastic film layer of 104 kg/j and a bending rigidity of 0.5× on the film layer.
After forming a thermoplastic film layer of 104 to 3.0 x 104 kg/cTi, and then forming a can body using the obtained laminate plate, the seaming part and hook joint part were heated to a temperature higher than the melting temperature of the laminate film. The present invention relates to a method for manufacturing a laminated metal can, which is characterized by bonding and sealing by heating.

As the metal plate for the can material used in the present invention, ordinary metal plates may be employed, such as tin plate, chromium-treated steel plate, mild steel plate, aluminum plate, galvanized steel plate, etc.

The plate thickness may be appropriately set depending on the intended use and performance of the metal can, and is usually selected within the range of 0.1 to 0.5 m. The thermoplastic film layer formed on the surface of the metal plate in the present invention is composed of two layers, and the lower layer (metal plate contact area) has a lower layer of bending rigidity (specifically, a film with a lower bending rigidity). Rate 0.01×104~0.4×104k
v/Cli) and a material with a high bending stiffness in the upper layer (specifically, a material with a bending stiffness of 0.5×
104 to 3.0 x 104 kg/Cit is preferable). With this arrangement, during the can manufacturing process, particularly during the seaming process, stress on the seaming machine can be alleviated, reliable seaming can be achieved, and damage to the curling portion can be prevented. The bending rigidity of the lower layer is preferably within the above range from the viewpoint of suitability for seaming, and the bending rigidity of the upper layer is preferably within the above range in order to prevent damage to the curling portion and improve the mechanical strength of the laminate board as a whole. On the other hand, the thermoplastic film layer is not limited in any way by its resin composition, and may be made of ordinary thermoplastic resins, such as olefin resins (polyethylene (e.g., acrylic acid-modified polyethylene "EAA93OO" manufactured by Union Carbide).
”), polypropylene (e.g., acrylic acid-modified polypropylene manufactured by Tonen Petrochemical Co., Ltd., “Tonen-modified PP”), copolymer resins of these with other polymerizable monomers, etc.), polyester resins (e.g., “Lumira” manufactured by Toray Industries, Inc.) Resins for the upper and lower layers may be selected from among polyamide resins (eg, "Diamid" manufactured by Daicel Chemical Co., Ltd.), vinyl resins, etc., within a range that satisfies the above-mentioned bending rigidity conditions.

Of course, it must be possible to obtain sufficient workability after lamination with the metal plate, and to have no pinholes, and in particular, it must be completely free from peeling of the film or glazing, etc. during the seaming process. be. In addition, the thickness of the thermoplastic film layer is usually in the range of 20 to 200μ in total thickness of the upper and lower layers, and the thickness ratio of the upper and lower layers is usually in the range of 1/9 to 9/1, but depending on the physical properties of the film used, An appropriate range may be selected depending on the capacity of the can making machine (particularly the seaming machine).

Hereinafter, the method for manufacturing a laminated metal can of the present invention will be described in detail.

First, a predetermined thermoplastic resin film is laminated onto the surface of the metal plate.

Such processing may be carried out by a conventional method, for example, the metal plate may be preheated to a surface temperature of 120 to 250°C, and the processing conditions may be a temperature of 150 to 250°C and a pressure of 5 to 30 kg/d. Next, the obtained laminate plate is press-worked into the predetermined member dimensions, and after these are subjected to a normal can manufacturing process to form a can body, the seaming part and the hook joint part are heated to a temperature higher than the melting temperature of the laminate film. Then, the film in the area is heat-sealed, bonded, and sealed.

In this way, the desired laminated metal can is obtained.

According to the laminated metal can of the present invention, which has the above-mentioned structural features, since two laminated film layers are formed on the can surface, corrosion of the outer surface of the metal can, especially corrosion of the seamed and curled portion, is completely prevented. Moreover, the combined effect of the film layer and the metal plate improves mechanical strength, so the thickness of the metal plate can be reduced, making it possible to reduce the weight and cost of the can.

Furthermore, there is no need to use harmful solder or special adhesives at the seaming and hook joints, and the laminate film itself is bonded and sealed by heat fusing, greatly streamlining the can manufacturing process. can. Next, the present invention will be specifically explained with reference to Examples.

Example 1 Can shape: 18t can (oil can) Can material metal: chromium-treated steel plate (thickness 0.3TWL) Laminated film lower layer: Union Carbide acrylic acid modified polyethylene "EAA93OO (film thickness 40μ,
Bending rigidity 0.1 x 104k97 Some upper layer: Tonen Petrochemical Co., Ltd. acrylic acid-modified polypropylene "Thonen modified PP" (film thickness 10μ, bending rigidity 1.4 x 104kvd)
) Lamination processing of the above chromium-treated steel plate surface temperature 250
After preheating at .degree. C., the two-layer laminate film is laminated using a laminator at a temperature of 200.degree. C. and a pressure of 30K9/C77F.

Through such processing, a thermoplastic film layer 2 having a low bending rigidity is formed on the surface of the metal plate 1 as shown in FIG.
}A laminate plate is obtained in which a thermoplastic film layer 3 having a large bending rigidity is formed. Can Making Method After the above-mentioned laminate plate is pressed into the predetermined dimensions of the top, bottom and body of an 18 ton can, a can body is constructed using a can making machine.

Next, the seam portion and hook joint portion of the can body are heated with an infrared burner to a surface temperature of 250° C. for 10 seconds to obtain a laminated metal can. Results Performance test of the laminated metal can obtained in this example (JIS-Zl
6O2) results are shown in Table 1.

Examples 2 and 3 The same procedure as Example 1 is carried out except that the following laminate films are used.

Table 1 shows the results of the performance tests for each of the obtained laminated metal cans. Example 2 Lower layer: Same acrylic acid modified polyethylene as Example 1 Upper layer: Toray polyester resin
Lumira-1” (film thickness 10μ, bending rigidity 1.2×104k
g/Cll) Example 3 Lower layer: Same acrylic acid-modified polyethylene as Example 1 Upper layer: Polyamide resin “Diamid” manufactured by Daicel Chemical Co., Ltd.
(Film thickness 10μ, bending rigidity 1.

0x104k9/Cfi) Comparative Example 1 A conventional solder-bonded tin can (plate thickness 0.32m, surface coated with a 10μ thick can clear coating) was subjected to a performance test in the same manner as in Example 1, and the results were Shown in Table 1.

Comparative Examples 2 and 3 The performance tests were carried out in the same manner as in Example 1, except that the following single laminate layer was formed, and the results of the performance tests are shown in Table 1.

Comparative Example 2 Acrylic acid-modified polypropylene manufactured by Tonen Petrochemical Co., Ltd. [Thonen PP] (film thickness 50μ, bending rigidity 1.4 × 10
4k9/d) Comparative Example 3 Mixture of epoxy resin "Kohon 828" manufactured by Ciel Chemical Co., Ltd./epoxy resin "Versamide 125" manufactured by General Mills Co., Ltd. at a weight ratio of 2/1 (film thickness 50μ, bending rigidity 5x104)
k9/al)

[Brief explanation of drawings]

FIG. 1 is a simplified cross-sectional view showing a laminate board, with 1
is a metal plate, and 2 and 3 are thermoplastic film layers.

Claims (1)

[Claims] 1. Bending rigidity of 0.01 x 10^4 to 0 on the surface of the metal can.
．． A thermoplastic film layer of 4 x 10^4 kg/cm^2 and a bending rigidity of 0.5 x 10^4 to 3 on the film layer.
．． A laminated metal can characterized by being provided with a thermoplastic film layer of 0x10^4 kg/cm^2. 2 The bending rigidity is 0.01 x 10^4 to 0.4 x 10^4 kg/cm^2 by laminating the surface of the metal plate.
a thermoplastic film layer and a bending rigidity of 0.5 x 10^4 to 3.0 x 10^4 kg/cm^2 on the film layer.
After forming a thermoplastic film layer, and then forming a can body using the obtained laminate plate, the seaming part and the hook joint part are heated to a temperature higher than the melting temperature of the laminate film to perform adhesion and sealing. Features: A manufacturing method for laminated metal cans.