Receptacles – End wall structure – Joint or seam between sidewall and end wall
Patent
1996-11-18
1999-01-26
Moy, Joseph M.
Receptacles
End wall structure
Joint or seam between sidewall and end wall
220669, 156 731, B65D 8500
Patent
active
058629394
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL AREA OF THE INVENTION
The invention falls in the technical area of the fabrication by drawing or drawing and ironing starting from a layered metal-plastic construction, of cans for use for example in packaging of beverages or foods and of containers for aerosols or of can ends, whether easy-open or not.
More precisely, the metal-plastic construction used in the present invention is of the type metal-polymer=metal, that is in which a layer of polymer is interposed between two metal sheets to which it is adhered.
In the text of this patent application, we will use without distinction for the designation of this construction the terms metal-plastic-metal, metal-polymer-metal, or more simply in the abbreviated fashion, MPM.
DESCRIPTION OF THE PRIOR ART
There are numerous documents describing layered metal-plastic constructions intended for the fabrication of food cans, beverage cans, or can ends. However, the majority of these concern the metal-polymer or polymer-metal-polymer constructions, the metal-polymer-metal constructions being rarer.
By way of illustration one can cite the international PCT application filed on Jun. 25, 1981 by Metal Box Limited and published under the number WO 82/00020 on Jan. 7, 1982. This application has given birth in particular to the European patent EP 055 719.
This patent describes a metal-plastic construction composed in its simplest form of realization of a polyethylene (called for abbreviation PE) film attached to a foil or plate of metal. Another method of realization consists of two films of PE attached to opposite surfaces of a metal plate to form a complex PE-metal-PE. Finally, a third method of realization consists of two plates or foils of metals attached to opposite surfaces of a PE film. The PE used, obtained by copolymerization under a low pressure of ethylene and of butene-1, is of the type linear low density and it has been found that this particular type, whose characteristics are described in the application, has the interesting property of adhering directly to the metal without needing to use an adhesive. It suffices to adhere it to the metal by the simultaneous application of heat and pressure (heat sealing).
The metallic substrate can be steel, steel having a coating of tin, or of chrome, or of chrome/chrome oxide, or of zinc, of aluminum treated or not with nickel, copper, or zinc. It can have undergone a chemical conversion treatment.
In the examples given, the films of different types of polyethylene of 100 microns thickness are thus heat sealed on the plates of different metals; steel, tin plated steel, steel coated with chrome-chrome oxide, or aluminum of a thickness of 2310 microns. The specimens obtained are then formed into hollow articles by folding, stamping, drawing, wall-ironing. The adhesion of the coatings is compared and demonstrates the superiority of linear low density polyethylene.
The French patent FR2 665 887 (Pechiney Emballage Alimentaire) describes a capsule to fit over a cork made by drawing, drawing and ironing, or flow turning, characterized in that it is comprised of two layers of aluminum bound together by an adhesive layer of shore hardness less than 80. The adhesive layer can be constituted of an ethylene acrylic acid or of polyethylene, or of polypropylene modified with acid functionality. The total thickness of the complex is comprised between 120 and 400 microns with the following percentage distribution of the total thickness:
Outer layer of aluminum 20 to 50%
Adhesive layer 3 to 30%
Inner layer of aluminum 40 to 60%
PROBLEM POSED
The problem presented to the inventors was that of improving drawn can bodies, in particular for food, of drawn and ironed cans intended for beverages and their ends, whether they be easy-open or standard.
The forming process for food cans is the drawing-redrawing process, that of beverage cans is drawing and ironing, that of ends is drawing. All of these processes permits very high production rates.
In all cases, one begins by a drawing pass. One starts with a circular disc of stee
REFERENCES:
patent: 2568029 (1951-09-01), Seeman
patent: 2660171 (1953-11-01), Dickinson, Jr.
patent: 2753868 (1956-07-01), Seeman
McHenry Robert J.
Petit Dominique
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