WO2006092073A1

WO2006092073A1 - Lid for a packaging corresponding production method and device

Info

Publication number: WO2006092073A1
Application number: PCT/CH2006/000113
Authority: WO
Inventors: Marcel Oberholzer
Original assignee: Elpatronic Ag
Priority date: 2005-03-03
Filing date: 2006-02-22
Publication date: 2006-09-08
Also published as: CH697975B1

Abstract

The invention relates to a lever ring (1) for containers made from coated sheet metal, enclosing a discharge opening, covered by a sealing film (10), whereby the cutting edge (20) of the lever ring itself has a coating (30) made from a hot melt material. A cover for the cutting edge of reliably high quality is thus achieved, on a lever ring with any coating, whereby a shaping of the inner edge region of the lever ring with regard to the coating of the cutting edge is not required. An effective protection against injury is also achieved.

Description

COVER FOR A PACKAGING, MANUFACTURING METHOD AND DEVICE THEREFOR

Reference to related applications This application claims the benefit of Swiss Patent Application No. 374/05, filed on Mar. 3, 2005, the entire disclosure of which is hereby incorporated by reference.

background

The present invention relates to a cover ring for containers made of coated sheet metal, which encloses a removal opening, which is covered with a sealing foil or covered, and which has a corrosion-protected cutting edge in the region of the removal opening. Furthermore, the invention relates to a method for producing a cover ring, wherein in a first step rondelles punched out of a coated sheet and in further steps both the rondel deformed and from this the removal opening is punched out, such that a covered with a sealing foil or covered cover ring arises. Furthermore, the invention relates to an apparatus for carrying out this method.

State of the art

Metal packaging, but also plastic packaging or packaging of other materials are suitable, e.g. perishable content in the long term to protect against environmental or mechanical influences. Safe packaging, by nature, makes it not easy to open; Once open, it can not be closed again.

In the field of drinks, cans with tear-open lids are known as "easy open". spreads; the lid has a scoring corresponding to the contour of the intended spout opening, so that when opening the corresponding lid area broken out and thus a removal opening can be formed.

Other solutions provide that in the sheet metal cover already provided a Aususussöffnung, but, for. is closed by a sealing film. The packaging is opened by tearing off the sealing foil. Still other packages have a permanently connected to the packaging body cover ring made of sheet metal, in which the actual lid, also consisting of sheet metal, is mechanically clamped.

Finally, in the field of food or animal feed, lids for packaging have become known which consist of a cover ring covered with a sealing foil. In addition to the advantage that such a package is relatively easy to open, it is added that the removal opening is very large and thus the content is well accessible except for small remnants. It is also possible, after the tearing foil has been completely torn off, to remove the packaging by means of a cover which is mechanically fixed in the cover ring, be it made of sheet metal or e.g. made of plastic, to reseal. The resulting consumer-friendliness are faced with disadvantages, such as, for example, the reduction in mechanical stability through the use of a large-area sealing film or the more difficult and expensive manufacture or filling of such a packaging.

Covering rings covered with a sealing foil are known, the cross-section of which is of the same design as that of conventional sheet-metal covers which are mechanically fastened to a packaging body made of sheet metal, e.g. a can, be connected by curling.

The present invention relates to such container lids, but is not limited to using these container lids to close a tin can; Container lid of the type mentioned Although they are particularly suitable for closing a packaging body made of sheet metal, they can readily be made of other materials, for example composite materials or film-type, semi-hard, aluminum-based materials, together with packaging bodies. The existing sheet metal lid ring then compensates for the lack of mechanical stability of the sealing film, so that throughout the desired mechanical stability of the packaging is given.

Of course, the requirements placed on such container lids correspond to those placed on conventional lids for sheet metal containers or other packaging bodies.

This includes corrosion resistance, not only against external influences, but especially against the contents, which is often chemically aggressive. Especially with moist or wet products corrosion is problematic in view of the long storage time, as required for packaging of the type mentioned. For this purpose, the sheet metal, from which the metal cover or made of sheet metal cover rings are made coated. This corrosion-resistant coating must in turn be mechanically highly stressed, since the deformation of the sheet to cover or cover ring on the one hand and the flange for the connection with the packaging body on the other hand represent an extreme stress on sheet itself and its coating.

Finally, the coating must be suitable for food or animal feed.

Then the geometry of the package, and thus of the lid, is not limited to round packaging bodies; Oval, rectangular or other shapes are widely used. In the present case, such forms should always be included in the term "lid ring": "lid ring" here refers to a carrier for a sealing foil, which in a round or not round, for example right can be used square and polygonal or other trained opening of a packaging body and connected to this. However, it is always the case that a "corner" has a certain radius of curvature, which is sufficiently large that the cover ring can be produced by forming a sheet metal section.

In addition, the production of packaging is predominantly a mass production, in which material consumption is a deciding factor in addition to that of the investment costs for the production line. At the same time, however, it is often required that a packaging, and thus its lid, can be produced even for small series or special applications.

The above-mentioned coating of the metal sheet to be used for a cover ring is known to those skilled in the art; It is usually on the inside of polyethylene terephthalate, a high-strength thermal paint that is capable of crimping and last but not least by this property and aggressive contents over the required storage life of sometimes several years resists. The outside is coated with polypropylene (PP), although such a coating is only reduced crimpable (i.e., mechanically stressed) because PP is preferably used as the adhesive or sealing medium, which in turn adheres in sufficient quality only to a PP coated surface. Both the PET and the PP coating have been tried and tested on an industrial scale.

The cover rings are usually produced as follows: Rondels are punched out of a metal sheet coated as described above, which are further processed in a combination tool. On the one hand, several forming steps take place until the desired profile of the cover ring is present, on the other hand, the interior of the rondel is also punched out, so that instead of a closed lid there is a cover ring. These punching processes produce raw cut edges without coating. Possibly a raw cut edge on the inside of the cover ring with dry contents and short storage time is no longer problematic; As a rule, however, corrosion is the result, which undesirably affects the contents and, for example, can affect the taste of food.

This sequence is counteracted by providing the cover ring on its inside with a so-called "retort curl". As a result, the raw cut edge is covered by a surface region of the cover ring and is no longer accessible to the contents.

Disadvantages of this solution are the comparatively high production costs, which occur in particular on the side of the tool. Above all, it is disadvantageous that the retort curl can not be produced today with the required high and uniform quality in a large series, even in mass production. Only slight deviations in the production lead to the irregular formation of the c-curl in such a way that the cut edge is not reliably covered. Even a slight change in the cross section of the rolled-up wall section results in that the cutting edge does not rest continuously on the corresponding surface region of the cover ring, so that the filling material can reach the raw cut edge.

From WO 01/07330 a solution has become known in which a cover ring is punched out of uncoated metal sheet. This has the consequence that the e- benfalls punched inside the Rondelle, since of course also uncoated, is easily reusable, which reduces the material costs of the corresponding produced cover rings. The subsequent coating of the molded cover ring must be done as a powder coating, since the conventional, suitable for the coating of metal sheets methods are not applicable.

On the one hand, this solution entails that the cut edge is also coated; disadvantageous lig is, however, that the powder coating of a geometrically complicated body, such as a cover ring, difficult to achieve in the required quality and, accordingly, is not suitable for industrial use. In particular, when the cover ring shown in Figure 3 of said document has to be further formed, a reliable coating by powder coating on an industrial scale can hardly be achieved. A further reshaping of the inner edge of the cover ring shown, however, is indicated that otherwise there is considerable risk of injury to the consumer after tearing off the sealing foil at the sharp cutting edge projecting radially inwards. In the case of dry contents, therefore, a so-called "c-curl" is usually provided in the industry, while in the case of aggressive contents, the "retort-curl" which is then necessary offers the inevitable protection against injury.

If a curl was formed after the powder coating in the cover ring, it must be assumed on the basis of the coating materials suitable for the powder coating that the mechanical stress during the deformation causes the coating to be damaged or weakened so that its protective quality is no longer sufficient. However, if the indentation of the curl takes place before the coating, such an unfavorable geometry for the powder coating results that it can scarcely be realized at reasonable cost in sufficient quality.

Presentation of the invention

Accordingly, it is an object of the present invention to improve the disadvantages mentioned.

This object is achieved by a cover ring according to claim 1, a method for its production according to claim 7 and an apparatus for carrying out the method according to claim 14. The fact that the cut edge of the inventive cover ring itself has its own coating of a hotmelt material results in a cover for the cut edge of reliably high quality on an otherwise arbitrarily coated cover ring, where ^¬ in a transformation of the cutting edge bearing inner edge region of the cover ring with regard to the cover of the cutting edge deleted. In addition to the stated task, there is an effective protection against injury, regardless of the position in which the cutting edge is located.

Due to the fact that, in the production method according to the invention for the cover ring according to the invention, the cut edge resulting from the removal opening is covered with a hotmelt material, this method can be integrated into the existing production process, with the result that proven and mature production processes, e.g. can be maintained for the coating of metal sheets for later production of cover rings. Beyond the task set, the elaborate tools for producing a "retort curl" are eliminated. In addition, the removal opening is particularly large, since this shrinking "retort curl" is unnecessary.

Because a hotmelt material can be applied to the cut edge in a targeted manner in the apparatus according to the invention for carrying out the production method, the lid ring according to the invention can be produced particularly easily.

In a preferred embodiment of the cover ring, the inner edge region which carries the cut edge engages a circumferential shoulder for sealing the sealing foil and is bent away from it (and the plane of the sealing foil), which increases the stability of the cover ring. In a particularly preferred embodiment, the edge region forms a substantially frusto-conical skirt, which coincides with the shoulder of a includes an angle between 45 degrees and less than 90 degrees. Thus, the cover ring is particularly rigid, with the advantage that even a highly aufgesiegelte tear-open can be easily opened without it comes through a twisting of the cover ring for jerky and uncontrolled release of the film.

In a preferred embodiment of the method according to the invention, the edge region is bent away from the shoulder at a right angle, the film is sealed, then the edge region is further shaped and finally the cut edge is covered with the hotmelt material. This allows a seal on an optimally narrow shoulder, with the advantage that material can be saved through the narrow shoulder and a removal opening enlarged in diameter or in terms of the internal dimensions can be created, even the cover ring is replaced by the frustoconical skirt Has stiffness which corresponds to that of a "retort curl".

BRIEF DESCRIPTION OF THE DRAWINGS Further embodiments, advantages and applications of the invention will become apparent from the dependent claims and from the following description with reference to the figures. Showing:

FIG. 1 a shows a cover ring according to the prior art with a "retort curl" in a view from above, without a sealing film,

FIG. 1 b shows the cover ring of FIG. 1 a in the same view, wherein a sealing film is sealed,

FIG. 2 a shows a cross section through the cover ring of FIG. 1 a, FIG. 2 b shows a cross section through another cover ring, but in a view corresponding to FIG. 2 a,

FIG. 3 shows a cross section through yet another cover ring, in a view corresponding to FIG. 2 a, with the film sealed,

Figure 4 shows the cover ring of Figure 3 at the moment of the seal, and

Figure 5 shows the lid ring of Figure 4 after a further forming step.

Ways to carry out the invention

In Figure 1 a, a lid ring according to the prior art is shown, which is still to string as an intermediate product with a sealing foil, in a view from above. Shown is a ^• bead 2, a shoulder 3 and a retort curl 4. Between the bead 2 and the shoulder 3 is a side wall 5, which is not visible as such in the selected view. The same applies to a downwardly bent edge region 6, the end of which is rolled up to the retort curl 4. The cover ring encloses the limited by the retort curl 4 removal opening. 7

FIG. 1 b shows the lid ring of FIG. 1 a with sealed-on sealing film 10 which covers the major part of the shoulder 3 and has a folded-over tab 11, via which the sealing film 10 can be torn away from the shoulder 3.

FIG. 2 a shows a cross section through the cover ring of FIG. 1 a at location AA. The edge region 6 is bent away from the shoulder 3 (and the sealing foil surface), substantially at right angles, and formed as a circumferential skirt which carries the retort curl 4 at its end. This in turn is caused by a helical curling of the outermost portion of the edge region 6; so that the cutting edge 20 is in Interior of the curl. Since the curl curl 4 rests on the edge region 6 due to the curling, the cut edge 20 is arranged concealed in relation to the filling material; a contact between the cutting edge 20 and filling material does not take place.

The upper side 12 of the cover ring 1 is preferably coated with polypropylene, referred to below as PP; the underside 13 preferably with polyethylene terephthalate (hereinafter called PET). The cutting edge 20 itself is uncoated, which it has been produced in the manner described above by a punching operation on the already coated sheet metal. It is highly corrosive, as not only the described coating with PP or PET is missing, but also the protective coating of tin, as it is present in the commonly used tinplate.

On the one hand, the arrangement shown is advantageous because it has a considerable rigidity due to the stepped structure and the retort curl 4 added structure. On the other hand, it is the case that, with the slightest production deviations, the retort curl 4 does not reliably keep the contents away from the cutting edge 20.

Figure 2 b shows a c-curl 9, which he can be used for dry and non-corrosive products.

FIG. 3 shows a lid ring 1 with sealing foil 10 sealed onto the shoulder 3, the edge region of which is designed as a substantially cylindrical skirt 6, which encloses a substantially right angle with the shoulder 3. The cutting edge 20 itself has its own coating 30 of a hotmelt material. In the figure, it is shown that the hotmelt material rests on the cutting edge 20 in the manner of a bead and preferably covers the adjoining area of the skirt 6 sufficiently far that the PET and the PP coating are achieved by hotmelt material and so that corrosion is excluded. Such covered with a sealing film 10 cover ring 1 is particularly suitable for packaging for aggressive products, is exposed to a rather stiff packaging body or mechanically not too great stress.

FIG. 4 shows the cover ring 1 of FIG. 3 during the sealing. A lower tool part 40 brings heat and pressure from below into the shoulder 3 / an upper tool part 41 brings heat and pressure from above to the sealing point of the sealing film 10 a. This is e.g. heated as a coating on the sealing film 10 provided PP, so that forms a seal between the film 10 and the shoulder 3 in a known manner. In particular, in sterilization products, the sealing surface has a width of 2 mm, so that the connection between the cover ring 21 film 10 can withstand the sterilization pressure. If the angle between the shoulder 3 and the skirt 6 is substantially 90 degrees, on the one hand the shoulder 3 can be kept as narrow as possible and on the other hand the removal opening can be kept as large as possible. A large removal opening (narrow shoulder 3 and discontinued retort curl 4) facilitates the removal of the last remnant of contents, if e.g. the packaging is kept at an angle for emptying or scratching out. An enlargement of the removal opening by about 2 millimeters, corresponding to the two-sided omission of a retort curl 4 (of one millimeter each) with otherwise constant outer diameter of the cover ring 1 may be referred to as a significant advantage. A corresponding method for the seal with an optimally narrow shoulder of the cover ring 1 is described in the parallel Swiss patent application CH 00275/05 the same applicant; This application is explicitly referred to.

FIG. 5 shows the cover ring 1 with the foil 10 of FIG. 4 sealed on, after the sealing and after a further forming process of the edge region 6 Edge region is pressed against the exterior of the lid 1 and forms a substantially frusto-conical skirt which encloses with the shoulder 3 at an angle of between about 45 degrees and less than 90 degrees. This configuration additionally increases the rigidity of the cover ring 1. After this further deformation of the edge region to the truncated cone-shaped skirt β, the hot-melt material 30 is applied to the cutting edge 20.

As a result, there is a covered with a film 10 cover ring 1, which is suitable for the closure of packaging with highly corrosive contents, ensures a maximum removal opening, through the elimination of complicated tools (for the formation of the retort Curl 4) is inexpensive to manufacture and moreover, it can easily be produced without errors in a large series.

Depending on the specific need for a special packaging, it is of course conceivable to make the cover according to the invention of the cut edge 20 by means of a hotmelt material on a c-curl or retort curl.

The hotmelt material is preferably applied directly and selectively to the cut edge 20 in a station of a device for applying hotmelt material to a cut edge 20 of a cover ring 1 operatively mounted in the latter from a nozzle of an extruder. In this case, the nozzle of the length of the cut edge is guided along this, so that a coating of hotmelt material deposited on the cutting edge 20. With a suitable relative movement between the cutting edge and nozzle results in a uniform coating of the cutting edge with hotmelt material. In a particular embodiment, a plurality of nozzles may cover an assigned part length of a cover over the cut edge 20, which reduces the production time of the individual cover ring 1 and thus allows increased production capacity.

Preferably, the nozzle is arranged in a device for coating a cut edge 20 such that that she delivers hotmelt material from above onto the cutting edge 20 lying below her. In particular, the person skilled in the art then has to choose the viscosity of the hotmelt material such that it flows down from the cutting edge surface laterally slightly on the skirt 6, so that the coating of the metal sheet adjacent to the cutting edge is somewhat covered. However, the viscosity must not be so high that too much Hotmeltmaterial flows down the side of the skirt 6 and thus the cover of the cutting edge itself thins and thus is poor quality.

For the purpose of the invention, a hotmelt material from Jowat with the name "Jowat Highterrα APAO-Hotmelt" can be used. The viscosity is then preferably between 1000 and 3500 mPas at 180 degrees. Celsius, more preferably selected from substantially 3000 mPas at 180 degrees Celsius.

While preferred embodiments of the invention are described in the present application, it is to be understood that the invention is not limited to these and may be practiced otherwise within the scope of the following claims.

Claims

claims

1. cover ring for containers made of coated metal sheet, which encloses a removal opening, which is covered with a sealing foil or is covered, and in the region of the removal opening has a corrosion-protected cutting edge, characterized in that the cut edge itself has its own coating of a Hotmeltmaterial.

2. Cover ring according to claim 1, characterized ^'by a circumferential shoulder for the Aufsiegelung

Sealing film and a subsequent thereto, bent away from the ^■ shoulder and the sealing foil surface edge region which carries the cutting edge.

3. Cover ring according to claim 2, characterized in that the edge region forms a circumferential, substantially cylindrical skirt which encloses a substantially right angle with the shoulder.

4. Cover ring according to claim 2, characterized in that the edge region forms a circumferential, substantially frusto-conical apron, which encloses with the shoulder an angle between 45 ° and less than 90 °.

5. cover ring according to claim 2, characterized in that the edge region is formed as a c-curl.

6. cover ring according to claim 2, characterized in that the edge region is formed as a retort curl.

7. A method for producing a cover ring according to claim 1, wherein in a first step rondelles punched out of a coated sheet metal and in further steps both the rondel deformed and from this the discharge opening is punched out, in such a way in that a covering ring which can be covered or covered with a sealing film is produced, characterized in that the cut edge resulting from the punching of the removal opening is covered with a hotmelt material.

8. The method of claim 7, wherein the sealing film is sealed onto the cover ring, characterized in that prior to the sealing process, a forming operation is performed such that the cover ring has a shoulder on which the film is sealable and one of the shoulder and the Sealing surface weggebogener edge region in the manner of a circumferential skirt is formed, which has the cutting edge and with the shoulder encloses a substantially right angle, and that - after the sealing process, the edge area further formed and finally the cutting edge is covered by the Hotmeltmaterial.

9. The method according to claim 8, characterized in that the edge region after the sealing process is further transformed such that it is frusto-conical and forms an angle of less than 90 ° with the shoulder.

10. The method according to any one of claims 7 to 9, characterized in that the hotmelt material is applied from a nozzle on the cutting edge, wherein nozzle and cutting edge perform a relative movement such that the cutting edge is swept by the nozzle over its length.

11. The method according to claim 10, characterized in that a plurality of nozzles sweep the cut edge over an assigned partial length.

12. The method according to any one of claims 7 to 11, characterized in that the viscosity of the hotmelt material is selected at application temperature so high that it can flow when applied on the cutting edge in order to cover their edges also, but not so high, that it is essentially at the side The cutting edge flows down so that the layer thickness thins out on the cut edge to be covered.

13. The method according to claim 12, characterized in that the viscosity of the Hotmeltmaterials between 1000 and 3500 mPas at 180 ° C, preferably 3000 mPas at 180 ° C.

14. A device for carrying out the method according to claim 7, characterized in that it comprises a station in which selectively a Hotmeltrαa- material can be applied to a previously prepared cutting edge of an operatively mounted in the station lid ring.

15. The device according to claim 14, characterized in that hotmelt material can be applied to the cut edge via at least one nozzle.

16. The apparatus according to claim 15, characterized in that the station is designed to produce during operation a relative movement between the at least one nozzle and the cover ring, such that the nozzle of the cutting edge is arranged along movable and can sweep them.