EP3279105A1 - Cover ring - Google Patents

Abstract

For sterilisable containers (1), a cover ring (7) is proposed, which consists of a metal ring (40) coated on both sides with at least one plastic layer (37, 43), a radially outer cutting edge and a radially inner, forming a lid opening (36) Cutting edge (33) is formed. The radially inner cutting edge (33) is folded back on itself at least once, and the fold is additionally pressed.

Description

The present invention relates to a cover ring. Furthermore, the invention relates to a container with a lid and a method for producing the cover ring.

For cans and cans packaging, it is known to provide them on their top with a permanently attached to the can or container sump lid made of metal. The permanently attached to the container sump lid is formed from a cover ring and a heat-sealed seal on the cover ring lid film. As lid films, in particular metal foils or composite films are used. The cover film closes the removal or lid opening formed by the cover ring for the contents of the package until it is used for the first time. In part, an additional, preferably made of plastic lid is placed over the metal lid to make the container again closed. The latter, however, is only necessary if the packaging content is not completely used up the first time the container is opened.

The requirements for a cover formed from cover ring and lid film are the same, which are also provided on conventional lids of containers, in particular of metal containers. This also includes corrosion resistance, both against environmental influences and against the contents. Such contents are at least partially chemically aggressive. Especially with moist or wet products, as they occur in the field of food packaging, especially in retort food products, corrosion in terms of longer storage life is a problem. Corrosion of the metal packaging material can here on the one hand to optical problems in the form of discoloration and on the other hand also lead to taste problems. Especially with canned fish the transfer of iron oxide into the product, also known as "ironing", leads to unacceptable changes in taste of the packaged food. To avoid corrosion, the sheet metal from which the container sump or the cover rings or the sealed-on metal foil is coated. In this case, the inside of the container facing the contents is usually coated with polyethylene terephthalate (PET) or a lacquer which withstands the mechanical stress during the production of the container and also withstands aggressive contents over the desired storage period of sometimes several years. The outside of the container is usually coated with polypropylene or a polypropylene-containing material, since polypropylene is preferably used as a sealing material for the lidding film. In other words, the side of the cover film facing the filling material coated with polypropylene is sealed onto the polypropylene-coated outer side of the cover ring facing away from the filling material.

When punching the lid opening or removal opening from the lid ring blank creates an uncoated cutting edge. Such a cut edge holds for the user of a corresponding container a certain risk of injury. With regard to corrosion, such a raw cut edge is unproblematic at most when dry and short shelf life. However, corrosion regularly occurs in such cases and leads to the above-mentioned adverse changes in the packaged food. A known from the prior art measure to prevent corrosion is to provide the lid ring on its side facing the contents with a rolled edge area at the cutting edge, a retort roller, also referred to as "retort curl" to provide. In this case, the cutting edge in the form of a roll inwards, that is, to the side of the filling out, bent and thus covered by a surface region of the cover ring. This means that the cut edge is usually no longer exposed to the contents. However, this solution causes quite high costs in the production of the corresponding tools. It is also particularly disadvantageous that even small deviations in the production lead to an irregular formation of the retort roll and lead to an irregular coverage of the cutting edge. Incidentally, also the Retort process, that is, the sterilization of the filling, by heating and cooling cause the contents itself or liquid from the contents in the retort roller passes.

In WO 01/07330 It is proposed that the coating of the molded sheet metal cover ring is made after punching the removal opening by means of powder coating. The powder coating of a geometrically complex body such as a cover ring in the desired quality, however, is difficult to achieve. Coating processes other than powder coating can not be used.

In WO 2006/092073 It is described to coat the cut edge of a lid ring separately with a hotmelt material.

The present invention has for its object to provide a cover ring or a corresponding lid and a corresponding container available, which or which avoid the disadvantages mentioned. Furthermore, the invention relates to a method for producing a cover ring.

The object is achieved by a cover ring according to claim 1. Preferred embodiments are the subject of the dependent claims. A lid is defined in claims 8 to 10. A method of manufacturing the cover ring is defined in claim 12.

A lid ring according to the invention comprises a metal ring with a radially outer cut edge and a radially inner cut edge forming a lid opening. The metal ring is coated on both sides with at least one plastic layer. The radially inner cut edge is folded back on itself at least once. The fold is also pressed.

In a preferred embodiment, a cover ring according to the invention comprises a metal ring with a radially outer cutting edge and a radially inwardly forming a lid opening cut edge. The metal ring is coated on both sides with at least one plastic layer. The radially inner cut edge is folded back on itself at least twice, as a result of which the cut edge is enclosed by the plastic layer lying on the inner side of the fold virtually without air. With folded inside side that side of a fold is designated with the smaller fold radius.

Since the radially inner cut edge is folded back on itself at least twice, it is not exposed to contact with the contents of the container. The cutting edge is enclosed by the multiple fold between the lying on top of the lid ring and the lid ring bottom plastic layers virtually air-free and -proof. As a result, almost complete protection against corrosion is achieved in a simple manner. In addition, this results in a protection against injury during handling of the container by the user. The radially inner cut edge can be folded both toward the lid ring underside, that is to the side facing the filling material, or to the lid ring upper side, that is to the side facing away from the filling material. If the radially inner cut edge is folded back two or more times onto itself, the fold always takes place on the same side.

Preferably, the radially inner cut edge is folded back exactly twice on itself.

In addition, one or more folds of the radially inner cut edge are preferably pressed. This achieves even better protection of the radially inner cut edge with respect to air and possibly with respect to contents.

In a preferred embodiment, a flange with a peripheral sealing zone arranged thereon is formed between the folded-back radially inner cut edge and a cover ring core wall. The circumferential sealing zone is preferably arranged on the side facing away from the contents of the flange, that is, on the lid ring top side arranged.

In a further embodiment, the radially inner cut edge is folded back on the opposite side of the sealing zone of the flange. That is, the radially inner cutting edge lies on the side facing the contents of the flange or the cover ring and thus on the lid ring bottom.

In a preferred embodiment, the metal from which the lid ring is formed is selected from the group consisting of aluminum, aluminum alloys, tinplate, black plate, and steel. Tinplate is a thin cold-rolled steel sheet whose surface is coated with tin. Currently, sheet thicknesses of 0.1 to 0.5 mm are common. Black plate is made of mild steel and is annealed, reacting with oxygen in the ambient air and preserving its dark appearance. When hot rolling, black plate is manufactured in thicknesses of 1.5 mm and more. Cold-rolled black plate, on the other hand, can be produced with thicknesses of 0.4 to 1.5 mm thinner and with a better surface finish.

In another embodiment, the plastic coating the two sides of the lid ring sheet is selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, and polyamide. The top and bottom of the cover ring sheet can be coated with the same plastic or with different plastics. As a rule, they are coated with various plastics. With the underside of the cover ring plate or cover ring, the filling material facing side is called. With the top of the cover ring plate or cover ring, the side facing away from the contents of the cover ring sheet is called.

The layer thickness of the plastic layers on the lower and upper side of the cover ring is generally 5 μm to 100 μm, preferably 10 μm to 50 μm and particularly preferably 20 μm to 40 μm. It can be arranged on both sides of the cover ring of the same plastic. However, the plastic layers arranged on the lower and upper side of the cover ring are preferably different, since they have to meet different requirements.

While the plastic layer disposed on the underside of the lid ring serves to prevent corrosion of the lid ring plate, the plastic layer disposed on the top side of the lid ring must be sealable since the lid film is sealed on a surface area on top of the lid ring, the sealing zone. Preference is given to using polypropylene (PP) or a polypropylene-containing material as the sealable plastic for the plastic layer on top of the cover ring. The top side of the cover ring facing side of the lid film is therefore preferably also coated with PP or a polypropylene-containing material.

In a further aspect of the invention, a lid with a lid ring according to the invention is described. The lid comprises the lid ring and a lid foil which is sealed in the sealing zone of the lid ring and closes the lid opening. The circumferential sealing zone of the cover ring arranged on the flange formed between the cover ring core wall and the radially inner cut edge is arranged on the upper side of the cover ring or on the outer side of the flange of the cover ring. The side of the cover film facing the filling material and thus also the upper side of the cover ring is preferably coated with PP or a polypropylene-containing material. But it can also be coated with another sealable material.

In a preferred embodiment, the lid film of the lid is preferably formed of plastic coated aluminum. In this case, the aluminum foil is usually coated on one side with plastic, wherein on the sealable side of the lid foil preferably polypropylene (PP) is arranged. The sealable side of the lid film opposite side is usually printed and / or painted. In addition to the plastic-coated aluminum composite films, other composite films can also be used as cover films, for example painted aluminum foils and laminated aluminum foils. In addition, aluminum-free composite films can be used as lidding films. However, all lidding films must have a sealable side to seal in the sealing zone of the sealant To produce cover ring.

In a further embodiment of the lid, the lidding film has an embossing or a printing. The lidding film may also have an embossing and a printing at the same time. Incidentally, unembossed lidding films can also be used.

In a further aspect of the invention, a container with the inventive lid or lid ring is described. The lid or the lid ring is preferably connected to the container sump by a rabbet joint. The connection between the cover and the fuselage could, however, also be made in a purely mechanical manner by positive locking and / or frictional engagement or gluing or hot-sealing or a combination of such fastening types in another way.

A method for producing the cover ring according to the invention comprises the step of at least simple folding of the radially inner cut edge. This creates a folded region in the radial direction. In this folded area, a double or multiple flange forms. After folding, the fold or the folded area is additionally pressed.

A preferred embodiment of the method for producing the cover ring according to the invention comprises the step of folding the radially inner cut edge. The cut edge is folded at least twice, a triple or multiple flange being formed over the area folded in the radial direction, and the cut edge is enclosed by the plastic layers lying on the inside of the fold virtually without air.

The cutting edge is bent or folded during the folding in the radial direction, thus forming a circumferential fold. The radius of the surface area folded in the radial direction is generally only a few millimeters, preferably 1 to 3 mm. By folding at least twice, the radially inner cutting edge by the on the Trapped inside the fold lying plastic layers almost free of air.

After folding in a further step, the folded area is additionally pressed in order to achieve an even better tightness of the fold against liquids, moisture and air and thus to better protect the enclosed cut edge from corrosion.

Fig.1

zeigt eine perspektivische Ansicht eines Gebindes mit einem Aufreissdeckel;

Fig. 2

zeigt eine perspektivische Teilansicht eines Deckelringrohlings;

Fig. 3

zeigt eine perspektivische Teilansicht eines Deckelringrohlings in einem weiteren Stadium der Herstellung;

Fig. 4

zeigt einen Querschnitt einer ersten Ausführungsform einer Schnittkante eines erfindungsgemässen Deckelrings;

Fig.5

zeigt einen Querschnitt einer zweiten Ausführungsform einer Schnittkante eines erfindungsgemässen Deckelrings;

Fig. 6

zeigt einen Querschnitt einer weiteren Ausführungsform einer Schnittkante eines erfindungsgemässen Deckelrings;

Fig. 7

zeigt einen Querschnitt der ersten Ausführungsform einer Schnittkante eines erfindungsgemässen Deckelrings mit aufgesiegelter Deckelfolie;

Fig.8

zeigt einen Querschnitt der weiteren Ausführungsform einer Schnittkante eines erfindungsgemässen Deckelrings mit aufgesiegelter Deckelfolie;

Further advantages, features and details emerge from the following description of preferred embodiments and with reference to the figures. Here are purely schematic:

Fig.1

shows a perspective view of a container with a tear-open;

Fig. 2

shows a partial perspective view of a cover ring blank;

Fig. 3

shows a partial perspective view of a cover ring blank in a further stage of manufacture;

Fig. 4

shows a cross section of a first embodiment of a cutting edge of an inventive cover ring;

Figure 5

shows a cross section of a second embodiment of a cutting edge of a cover ring according to the invention;

Fig. 6

shows a cross section of a further embodiment of a cutting edge of a cover ring according to the invention;

Fig. 7

shows a cross section of the first embodiment of a cutting edge of an inventive cover ring with sealed lid sheet;

Figure 8

shows a cross section of the further embodiment of a Cut edge of a cover ring according to the invention with lid film sealed on;

Fig. 1 shows a container 1 with a container sump 5, a Aufreissdeckel 3, which in turn comprises a fixed to the container sump 5 lid ring 7, a lid film 10 and a tear tab 15 includes. The cover film 10 closes the removal opening of the tear-open lid 3. The cover film 10 is provided with a tear-open tab 15 for opening the lid 3. In the view of FIG. 1 is no difference of the container according to the prior art to a container with the inventive cover ring visible.

Fig. 2 shows a partial perspective view of a cover ring blank 18. For clarity, only a part of a whole lid ring blank 18 is shown. Shown is the package-side formation of the cover ring blank 18 for a rabbet joint of the cover ring with the container sump (not shown). The seaming edge 21 has, in the radial direction toward the center of the lid ring blank 18, a fold radius 22 with which the seaming edge 21 merges into the lid ring core wall 23. The lid ring core wall 23 is followed by the lid ring depth radius 24, which merges into the lid ring bottom 27. As can be seen from the figure, no lid or removal opening has yet been punched out in this production stage of the blanking blank.

Fig. 3 shows a partial perspective view of a cover ring blank 18 in a further stage of its manufacture. The cover ring blank 18 again has a folded edge 21 on the package side, a fold radius 22, a lid ring core wall 23 and a lid ring depth radius 24. In this production stage, the cover ring blank 18 now has a removal opening 36. The cover ring depth radius 24 merges into the flange 31 in the direction of the removal opening 36. The removal opening 36 is formed by the radially inward cutting edge 33 formed during the punching step. On top of the flange 31 there is a sealing zone 30 on the upper side of the cover arranged.

Fig. 4 In the embodiment shown, the cover ring has a layer stack structure with the following layers, a cover layer arranged on the upper side plastic layer 37th , a metal layer in the form of a metal ring 40 and a cover ring arranged on the underside plastic layer 43. Here, the cover ring arranged on the underside plastic layer to the Füllgutraum (not shown) facing and the cover ring upper side plastic layer on the side facing away from the Füllgutraum the cover ring 7 and thus arranged to the outside of the container 1 out. In this embodiment, the radially inner cut edge 33 has been folded back twice on itself. The folding took place twice towards the cover ring underside, so that the enclosed cut edge 33 comes to rest on the side of the lid ring 7 facing the filling material space. In the folded area d, the flange 31 is thus formed in three ways. On the upper side of the cover ring, the sealing zone 30 is furthermore arranged, which extends beyond the folded area d out to a maximum of the cover ring core wall (not shown). The cutting edge 33 is enclosed by the plastic layers (37, 43) lying on the inside of the fold (46, 47), virtually without air.

Fig. 5 shows in cross-section a section of a second embodiment of an inventive cover ring 7. In this embodiment, the double fold to cover ring top side out, so that the trapped cutting edge 33 on the Füllgutraum (not shown) facing away from the cover ring 7 comes to rest. In the folded region d, the flange 31 is again formed in three ways. Since now arranged in the folded area d on the Füllgutraum facing cover ring inner side plastic layer 43 comes to rest on the lid ring outer side, the selected plastic preferably also sealable. If the folded portion d has a sufficient radius, the sealing zone 30 can be limited to the folded portion d. However, it is also possible to extend the sealing zone 30 beyond the folded area onto the outer part of the flange 31 lying in the radial direction up to the lid ring core wall (not shown). In this variant, however, the sealing zone 30 is interrupted by a gap 45.

Fig. 6 shows in cross section a detail of another embodiment of an inventive cover ring 7. As in the in Fig. 5 In the embodiment shown, the cutting edge 33 is folded back twice onto the cover ring top side. About a gradation 48 in the region e corresponding to twice the thickness of the plastic coated cover ring 7 on both sides, the cover ring top comes in the folded area d to lie in the same plane as the radially outer portion of the flange 31. The sealing zone 30 can be easily over entire radial Length of the flange 31 are maximally extended to the cover ring core wall (not shown). In the region of the gradation 48, the sealing zone 30 is interrupted by a gap 45.

Fig. 7 shows the in Fig. 4 illustrated embodiment of the inventive cover ring 7, which in turn is shown in fragmentary form. In the sealing zone 30, a cover film 51 is sealed on the cover ring-side upper plastic layer and thus on the upper side of the cover ring. The sealing zone 30 extends in the illustrated example over the entire flange 31, that is, over the folded region d, in which the flange 31 is formed in three, further on the radially outer region of the flange 31 to a maximum towards the cover ring core wall (not shown). , The double folding of the radially inner cutting edge 33 was carried out in this embodiment to the lid ring bottom and thus to Füllgutraum 55 out. The lying on the inside of the fold (46, 47), arranged on the metal layer in the form of a metal ring 40 plastic layers 37 and 43 almost free of air trapped cutting edge 33 is therefore on the Füllgutraum 55 facing lid ring underside.

Fig. 8 shows the in Fig. 6 illustrated embodiment of the inventive cover ring 7, which in turn is shown in fragmentary form. In the sealing zone 30, a lidding film 51 is sealed on the cover-ring-side upper plastic layer. Since in this embodiment the double folding of the radially inner cut edge 33 takes place towards the upper side of the lid ring, the cutting edge 33 enclosed between the plastic layers 37 and 43 lies on the upper side of the lid ring, facing away from the filling space 55. The gradation 48 in the region e lies in the folded region d lying on the cover ring upper side plastic layer 43 in a plane with the on the metal layer 40 on the Füllgutraum 55 facing away from the upper lid ring plastic layer 37. The lid film 51 can therefore be sealed without difficulty in the arranged on the flange 31 sealing zone 30. The sealing zone 30 extends beyond the folded region d further beyond the radially outer region of the flange 31 to at most toward the cover ring core wall (not shown). The cover film 51 closes on the one hand the removal opening (not shown) and also the gap 45 formed by the step 48 in the region e.

Claims (13)

Cover ring (7) comprising a metal ring (40) coated on both sides with at least one plastic layer (37, 43) with a radially outer cut edge and a radially inner cut edge (33) forming a cover opening (36), characterized in that the radial inside lying cutting edge (33) folded back on itself at least once and the fold is pressed. Lid ring according to claim 1, characterized in that the radially inner cut edge (33) folded back on itself at least twice and is trapped by the lying on the inside Falzinnenseite (46, 47) plastic layers (37, 43) almost free of air. Lid ring (7) according to claim 2, characterized in that between the folded-back radially inner cut edge (33) and a lid ring core wall (23) is formed a flange (31) having a circumferential sealing zone (30) arranged thereon. Lid ring (7) according to claim 3, characterized in that the radially inner cutting edge (33) is folded back on the sealing zone (30) opposite side of the flange (31). Cover ring (7) according to one of the preceding claims, characterized in that the metal of the metal ring (40) is selected from the group consisting of steel, tinplate, black plate, aluminum and aluminum alloys. Cover ring (7) according to any one of the preceding claims, characterized in that the plastic of the plastic layers (37, 43) is selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate and polyamide. Cover ring (7) according to one of the preceding claims, characterized in that the plastic layer (37, 43) has a layer thickness of 5 .mu.m to 100 .mu.m, preferably, 10 .mu.m to 50 .mu.m and particularly preferably from 20 .mu.m to 40 .mu.m. Cover with cover ring (7) according to one of claims 3 to 7, characterized in that in the sealing zone (30) a cover opening (36) closing lid film (51) is sealed. Lid according to claim 8, characterized in that the cover film (51) is a composite film selected from the group consisting of plastic-coated aluminum, laminated aluminum, painted aluminum and aluminum-free composite films. Lid according to claim 8 or 9, characterized in that the cover film (51) is a composite film and preferably has an embossing and / or printing. Container (1) with a lid according to one of claims 8 to 10, characterized in that the lid is connected by a rabbet joint with a container sump (5). A method for producing a cover ring (7) according to one of claims 1 to 7, characterized in that at least simple folding of the radially inner cut edge (33) via a folded in the radial direction region (d) a two- or multiple flange (31 ) is formed and wherein after folding of the folded area (d) is additionally pressed. A method for producing a cover ring (7) according to claim 12, characterized in that at least twice folding the a three-fold or multiple flange (31) is formed on the radially inner cut edge (33) via a region (d) folded in the radial direction, and the cut edge (33) is formed by the plastic layer (37, 43) lying on the fold inside (46, 47) ) is trapped almost free of air and wherein after folding of the folded area (d) is additionally pressed.

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