CLOSURE MEANS FOR CANS, ESPECIALLY PRESERVED FOOD CANS

Abstract: Starting with a can with a body (1) of-any configuration, based on conveniently treated sheet metal, the seal of the invention consists in using a cover (4) materialized in a stratified lamina, based on an external layer of aluminum and an internal layer plastic in nature, which is secured to the mouth of the body (1) by means of welding, by means of adhesive or by any other means, and which has a fluke (5), prolongation thereof and serving as a handle. The stratified lamina (4) constituting the cover itself can be secured directly to the mouth of the body (1), conveniently configured in this respect, or it can be assisted by a perimeter frame (2), also of sheet metal, fitted with an internal perimeter flange (3) to which is secured the stratified lamina (4), the cover (2-4) being secured as a whole, to the body (1} of the container, by the classic flange system.

Description: OBJECT OF THE INVENTION The present invention relates to a seal for cans, especially for preserves, like for example of asparaguses, tomato, peppers, etc., of any configuration, and obtained from tinplate, aluminium, or any other material suitable for this purpose, the objective being to facilitate considerably the operation of opening said cans, without detriment to the sealing properties in themselves, insofar as the conservation of the content thereof is concerned, and with a total absence of risk during the opening manipulation. A can disclosing the features in the preamble of claim 1 is described in document EP-A-0 090 957. BACKGROUND OF THE INVENTION As it is well known, conventional preserve cans are structured by means of a body, from sheet iron suitably treated both externally and internally, which body can adopt a prismatic, cylindrical or other configuration, and which in all cases after being filled, receives over their mouth a sealing cover, also metallic, of similar characteristics, which is flange mechanically on the aforementioned mouth determining, as well as an airtight seal, a rim usable in the later opening operation, as a means of support for the classic can opener. This opening problem becomes worse in the preserve cans that contain fruit of considerable size like asparagus, not only for its larger size, but also because the form thereof, based on a succession of noticeably curved straight segments, create problems both for these last-mentioned segments both when the opening is carried out with a manual can opener and when it is carried out with an electric one. One of the solutions that has been given for the difficulty or inconvenience of opening preserve cans, has been the use of "easy-open" cans, in which the cover comes, in the vicinity of the aforementioned rim, with a stamp determining a weakened line that allows relatively easy opening, by ripping, to which effect the detachable sector of the cover has an associated ring, usable initially as the means to initiate the tear and immediately thereafter as opening puller. This solution has been applied to all types of can, cylindrical, rectangular and oval. Although it allows quicker opening of the can, it presents on the other hand, a problem which is centred fundamentally on two aspects, on one hand on many occasions breaking of the opening ring occurs, rendering the system unusable, and on the other hand and much more frequently, when the material employed is tin, cuts are produced in the hands and/or fingers of the users, due to said tinplate constituting the detachable sector of the cover, during the opening operation, presents a very sharp cutting edge. This problem could be resolved partly by the use of aluminium cans, but this solution would imply a significant increase in cost in that, for storage and transport requirements, this type of can is stacked up to very considerable heights and, since the mechanical strength of aluminium is considerably less than that offered by tinplate for an identical can cost, a noticeable increase would be necessary in the thickness of wall thereof to avoid the crushing of those that occupy the lower layers or a higher cost which is not always accepted by the market because canned products are not usually products of high unit price. Furthermore, it is necessary to bear in mind that the canning process of certain fruits, like asparagus for example, involves sterilization in which the cans are subjected to a temperature of up to 120° C in sterilizers which work under pressure that counteracts the interior outward pressure produced by the content of the can as a consequence of the heating thereof. DESCRIPTION OF THE INVENTION The seal for cans that the invention proposes resolves in a fully satisfactory manner the problem explained above in the two commented aspects, assuring an extraordinarily quick and easy opening and without the least risk of harm for the user, and likewise taking advantage of the form of sterilization which certain fruits undergo. In brief, then, the invention in a can for preserves of any configuration which, for example, in the case of asparagus adopts a rectangular form, with its corners rounded wherein one of its larger faces has been stamped or hollowed and substituted in its greater part by an aluminium and plastic film which is easily pealed away. To this end and in more specifically, the invention centers upon substituting most of the classic rigid cover of the can, based on treated sheet metal, by a stratified lamina based on an aluminum and plastic composite, of those already in use in the foodstuffs industry, although with other different applications. The substitution of part of the cover by means of the stamping thereof leaves the edge thereof uncovered, which remains in contact with the internal content thereof. It is consequently necessary to solve the problem that is posed by the nature of conserving liquid in the case of preserves, because it is composed, mainly, of water and salt. Such a composition proves highly corrosive for the iron of which the can is made and which, on rim that is produced by the stamping of the cover, is not coated with the resin that coats the rest of the interior of the container, protecting it from corrosion. This problem has been solved satisfactorily by means of implementing upward shoulder or flange. This flange, at the time of fabricating the cover, determines a small hole which is filled with the interior coating of the cover and of the can, and which impedes, together with the shoulder formed, that the conserving liquid comes into contact with the rim of the stamped cover, avoiding thereby its corrosion. In accordance with the invention, the aforementioned stratified lamina is supplemented, within the context of the cover, with a frame of metallic nature, similar to the perimeter area of the cover of a conventional can, said frame provided with an internal perimeter flange through which is secured thereto, prior to the seal, the stratified lamina which completes the cover, whereby the cover as a whole can be coupled to the body of the can with the conventional machinery used for such in classic preserve cans. According to the invention, the cover may come without the aforementioned frame, being simply materialized in the stratified lamina that has been mentioned above, in which case the body of the cannot be conventional but rather must be provided in its mouth with an internal perimeter flange, similar to that aforementioned for the frame, with the same purpose of allowing the securing of the stratified lamina. In any case, said lamina will be secured either to the frame or directly to the mouth of the body of the can, by welding or by any other appropriate method which, as well as a leakproof and stable seal that withstands the sterilization treatment in autoclave, allows easy opening by means of manual pulling on a fluke, free prolongation of a point whatever of its contour. In any one of the two aforementioned embodiments, either the internal marginal area of the frame or the marginal area of the mouth of the body of the can, will be turned upward and outward out so that the rim is conveniently isolated from the interior recipient, after sealing the can, the object being to avoid problems of oxidation through said rim being in contact with the conserving liquid, made up of water with salt, mainly, since for the production of the can, one starts with a metal sheet coated with a varnish, resin or plastic on the inside to avoid its oxidation, coating element that obviously does not affect the rim obtained in the stamping operation. DESCRIPTION OF THE DRAWINGS To complete the description that is being made and with the object of assisting in a better understanding of the characteristics of the invention, in accordance with a preferred example of practical embodiment thereof, said description is accompanied, as an integral part thereof, with a set of drawings wherein, by way of illustration and not restrictively, the following has been represented: Figure 1. This shows a view in perspective of one of the cans, provided with the seal which constitutes the object of the present invention. Figure 2. This shows an exploded and sectional detail of the can of the previous figure, at the level of its mouth and according to a first embodiment of the invention. Figure 3. This shows a sectional detail similar to that of figure 3, but corresponding to the second embodiment of the invention. Figure 4. This shows a similar can to that of figure 1, in which its lower base has been implemented by means of a body distinct to that of the side and joined thereto by means of a flange similar to that of figure 2. Figure. 5. This shows a view in perspective of other possible configurations that the cans may adopt. PREFERRED EMBODIMENT THE INVENTION In the light of these figures, more specifically of figures 1 and 2, it can be seen how the seal that is proposed is applicable to preserve cans obtained from sheet metal, pressed and suitably treated both internally and externally, to withstand external environmental effects and those resulting from their own content. Now in accordance with the invention, the aforementioned body (1) is completed with a cover structured by means of a perimeter frame (2) which is secured to the mouth of the aforementioned body by the conventional flange system, as shown in figure 2, with the particularity also that in said frame (2) an internal perimeter flange (3) is defined, preferably included in an imaginary horizontal plane, to which is secured by welding, by means of adhesive or by any other appropriate means, a stratified lamina (4) which completes the cover and which will be obtained by means of a classic composite based on a fine aluminum sheet clad internally with a plastic lamina. Clearly the system of securing the cover should offer enough strength to withstand the sterilization treatment in autoclave, as has been stated previously. This stratified lamina (4), which is secured tightly to the flange (3) over the full length of the latter, will be inserted in the classic recess defined by the rim (2), except for a fluke (5), prolongation thereof and which constitutes a handle employable in the opening operation. Nevertheless and in accordance with the embodiment variant shown in figure 3, the possibility exists that the frame (2) is not present, so that the flange (3') is obtained from the actual body (1) of the can, by means of folding the mouth thereof, securing the aforementioned stratified lamina (4), as in the previous case, to this flange (3'), said lamina having likewise the fluke (5) for manual pulling. In any one of the two variants mentioned, it is foreseen that the flange (3-3') incorporates a fold (6) in the marginal area corresponding to its free edge, oriented upward and outward, as can be observed especially in figures 2 and 3, so that the said free edge (7) is perfectly isolated from the interior of the can and protected from of the effects of oxidation by the cover (4) itself. In this sense the fold (6) mentioned should be implemented, as may also be observed in figures 2 and 3, so that the flange (3-3') as a whole offers a perfectly flat external surface for a good adaptation of the cover (4). In any case, the can will offer a relatively similar appearance to that of a classic can, with the only exception that its cover (4) passes from being rigid to being semi-rigid, maintaining optimum conditions regarding the tightness of the seal and with the outstanding advantage that its opening is carried out in an extraordinarily quick and simple way, by means of simple pulling on the fluke (5) and without the least risk of harm for the user during said opening operation. Figure 4 represents a figure similar to 1, but wherein the lower base has been implemented by means of a body distinct to that of the side (1). This base is joined to the perimeter and side body by means of an rim (2) similar to that shown in figure 2.

Claims: Sealed can, specially for preserves, comprising a body (1) of any shape based on a sheet metal suitably treated both on its external surface and on its internal surface, the body (1) having a top open base in which an internal perimetric flange (3-3') is provided defining a marginal area (6), and wherein a foil (4) is secured to said perimetric flange (3-3') by heat-welding, said marginal area (6) being folded upwards and outwards into itself forming a substantially cylindrical shape, wherein the edge (7) of said marginal area (6) contacts with the flange (3-3') defining therewith a perimetric groove characterised in that said foil (4) is a stratified foil (4) with an external layer of aluminium and an internal layer of plastic, and in that said perimetric groove is filled with the internal coating of the foil. Sealed can according to claim 1, characterised in that the flange (3') is obtained by means of folding the top open base of the body (1). Sealed can according to claim 1, wherein the flange (3) is an internal perimeter flange of a rigid metallic perimeter frame (2) firmly coupled to a top open base of the body (1). Sealed can according to any of the preceding claims characteriersed in that the stratified foil (4) is joined to the flange (3-3') on its inner and flat area, said joint not affecting the fold or internal edge (6) of said perimetric flange (3-3'). Sealed can according to any of the preceding claims, characterised in that the stratified foil (4) has an external prolongation (5) serving as a handle. Sealed can according to any of the preceding claims, wherein the marginal area (6) is folded in a manner such that the flange (3-3'), as a whole, offers a flat external surface for a good adaptation of the foil (4).

Inventors: ARAMENDIA ZUAZU JOAQUIN, ERDOCIAIN BRAVO PEDRO, ARAMENDIA ZUAZU, JOAQUIN, ERDOCIAIN BRAVO, PEDRO
Applicants: IND ALIMENTARIAS DE NAVARRA S, INDUSTRIAS ALIMENTARIAS DE NAVARRA, S.A.
Application year: 2001
Main classification: B65D17
IPC codes: B65D77