WO2021009119A1

WO2021009119A1 - Method and apparatus for producing tear-open lids, and tear-open lid

Info

Publication number: WO2021009119A1
Application number: PCT/EP2020/069751
Authority: WO
Inventors: Peter Taiana
Original assignee: Soudronic Ag
Priority date: 2019-07-18
Filing date: 2020-07-13
Publication date: 2021-01-21
Also published as: TW202110551A; CH716413A1

Abstract

The invention relates to a method for producing tear-open lids (10), in the case of which a lid blank (1) is provided on both sides with a coating, the lid blank (1) is formed into a lid ring (2) with a central removal opening (15), which is surrounded by an initial flange (44), the initial flange (44) is subjected to a drawing process to form a sealing flange (7) and a collar (4), which projects away from the sealing flange (7), an annular strip (32) made of a thermoplastic material which is compatible with the coating layer is applied to the collar (4) on an outer collar side (41a), which is directed away from the removal opening (15), or on an inner collar side (40), which is directed towards the removal opening, the free end (31) of the collar (4) is rolled in towards the outer collar side (41a), or towards the inner collar side (40), until the rolled-in formation (33) comes into full-circumference contact with the annular strip (32), and a tear-open film is sealed onto a sealing surface of the sealing flange (7).

Description

l

Method and device for the production of easy-open lids and easy-open lids

Reference to related documents

This document claims the priority of Swiss patent application No. 0921/19, filed on July 18, 2019, the entire content of which is hereby incorporated by reference.

Field of invention

The invention relates to a method for the manufacture of tear-open lids, a device for the manufacture of tear-open lids and a tear-open cover according to the respective independent claim.

background

Tear-open lids are used to close containers and are typically used in the food industry for packaging food. The tear-off lids comprise a lid ring which is attached to the opening of the container. A tear-off film is attached to the lid ring, which must be peeled off before the contents of the container are consumed. If such a container, which is closed with the tear-off lid, contains a liquid, corrosive filling material such as salt water, the bare cut edge of the lid opening of the container can corrode. In the case of a tear-off lid with a so-called retort curl, there is a certain degree of curling of the area with the cut edge upwards and inwards and with the overlap by the tear-off film Protection against the influence of the product. The bare or possibly corroded cut edge is also not visible. However, depending on the aggressiveness of the product and the storage time of the filled container, traces of corrosion can still be visible. In EP-A 1 153 840 it is proposed that the tear-off film is also sealed on the curl itself, as a result of which the cut edge is protected from the contents of the can by a seal. It turns out, however, that the sealing both on the sealing flange and also on the rolling in production with a high manufacturing rate is difficult to master perfectly. WO-A 02/790041 mentions in passing that the can in the Einrol ^¬ lung resulting gap with the heat-sealable coating of the tear-open fill, without explaining how this would tatsäch Lich feasible in the industrial production of Aufreissfolien. Known tear-off foils are only provided with a very thin heat-sealing layer and it is not apparent to the person skilled in the art how this layer can be used to fill the gap when a heat-sealing known to the person skilled in the art is carried out. The possibility mentioned in WO-A 02/790041 can therefore hardly be implemented in practice. WO 2018/191828 Al suggests that the collar is placed a band-shaped strip of plastic on ^¬ on the inside of the collar before the curling of the free end. Nonetheless, even with this solution, in rare cases the contents of the container may come into contact with the cut edge, making the view unappetizing for the consumer.

Presentation of the invention

The invention is based on the object of creating a method and a production device for tear-open lids, with which a tear-open lid can be produced industrially at high rates and at low costs, and that too In the case of corrosive products, the possibility of contamination of the contents due to corrosion of the cut edge is minimized.

The object is achieved in a first aspect of the invention with a method for producing tear-open lids according to claim 1 and in a second aspect of the invention with a device for producing tear-open lids according to claim 10.

In that an annular strip is applied to the outside or inside of the collar and then the collar is rolled up to form a so-called "reverse curl" towards the outside of the collar or to form the "retort curl" towards the inside of the collar back, the cut edge exposed as a result of the punching is brought into contact with the annular strip and sealed by it.

If the subsequent curling of the collar to form the "reverse curl" takes place towards the outside of the collar, the product is also prevented from collecting between the curling and the tear-off film, with the cut edge being protected from corrosion at the same time. This minimizes the risk of the user himself or the rest of the product in the container comes into contact with this accumulation of product after peeling off the tear-off film. Last but not least, the appearance is improved after peeling off the tear-off film because the user does not see any "dirty" curling.

The preferred positioning of the ring-shaped strip in the corner area on the outside of the collar is advantageous for reverse curl, as this offers very good stability due to the partially horizontal application, in contrast to a completely vertical application on the wall of the collar.

Furthermore, the invention is based on the object of creating a tear-open cover which does not have the disadvantages mentioned and which can be produced industrially in a high rate and quality at low cost. This object is achieved with a tear-off cover with the features of claim 15.

Brief description of the drawings

Further embodiments, advantages and applications of the invention emerge from the dependent claims and from the description that follows with reference to the figures. Show:

1 shows a schematic side view of an apparatus for producing tear-open lids;

2 shows a vertical sectional view of a cover ring in the production of a tear-open cover according to the invention;

3a shows an enlarged view of part of the cover ring from FIG. 2 after further manufacturing steps in a first embodiment;

3b shows an enlarged view of part of the cover ring from FIG. 2 after further manufacturing steps in a second embodiment;

4 shows a schematic representation of the processing station for applying the seal, in particular with the positioning of the application nozzle for applying the plastic for a tear-off lid with reverse curl;

FIG. 5 shows the cover ring from FIG. 2 after a roll of the edge of the removal opening;

6 shows a plan view of the cover ring of a tear-open cover with retort curl; and

7 shows a plan view of the cover ring of a tear-off cover with reverse curl.

Definitions used below

The following terms are defined for the present text: - With regard to a collar 4 (Fig. 3a, 3b), a collar inner side 40 directed towards the removal opening and a collar outer side 41a directed away from the removal opening,

- With regard to the lid blank 1, the lid ring 2 and the tear-open lid 10, a lid outside or "outside" in the direction of the surroundings of the later container closed with the tear-off lid (reference number 7, 40) and a lid inside or "inside" for the side facing the interior of this container (reference numerals 41a, 41b in FIGS. 3a, 3b).

Ways of Carrying Out the Invention

Fig. 1 shows schematically an apparatus for producing tear-open lids. Fig. 2 shows a vertical sectional view of a cover ring in the production of a tear-open cover according to the invention and FIG. 3a and 3b each show an enlarged view of part of the cover ring of FIG. 2, each with a different embodiment of the annular strip 32. In the following, reference is made again and again to FIG. 1 in the description of the cover rings shown in order to establish the connection with the to show individual manufacturing steps or processing stations.

At the beginning of the transport route of the manufacturing device 20, a stack 12 is shown, which contains a plurality of cover blanks 1, which are individually stacked and processed along the transport path by various processing stations, with cover rings 2 being formed from the cover blanks 1 first and then up to the finished tear-off cover 10 further processed who the. The cover blanks 1 are, for example, round disks made of coated metal that is largely protected against corrosion, such as tin-coated steel, also known as tinplate, or tin-free steel (Tin Free Steel; TFS). Under TFS one with an electrolytic Applied chrome coating provided steel (Electro- lytic Chromium Coated Steel, ECCS) understood. In the context of this invention, TFS has proven to be particularly well suited because, due to the electrolytic deposition of the chromium, it provides a good substrate for the further processing steps (good adhesion for paints).

Since the chrome layer on the later inner side of the lid 41a, 41b should not come into direct contact with the contents of the can, e.g. food, and the later outer side 7, 40 of the lid should be heat-sealable in some areas, the sheet metal is on both sides, at least in the relevant areas of the sealing flange 7 and of the collar 4, with respect to the inside of the lid 41a, 41b, preferably on the entire inside of the lid 41a, 41b with a lacquer layer described in more detail in the context of the present invention. The outer lacquer layer can be different from the inner lacquer layer, but in the context of this invention it should at least have similar properties, in particular with regard to the polarity and the melting points. The same paint is preferably used for both paint layers.

Similar polarity is to be understood as meaning that both are either apolar or polar, the same polarity means that they have the same degree of polarity.

In order to improve the adhesion of the paint layer on the sheet metal, it has been found to be preferred to provide the sheet metal with a primer before the paint is applied. Primers or adhesion promoters for metal surfaces are known and commercially available. The choice of primer depends, among other things, on the composition of the paint whose adhesion it is intended to improve. Since the chrome coating is oxidized in the contact area with air, adhesion can be achieved, for example, by means of special silanes which, in addition to the silanol groups, contain functional groups that are also part of paint components. In addition, suitable primers do not contain any wax components. In the context of this invention, suitable paints contain at least one component which is liquid at room temperature and which can be a resin component and / or a solvent. Thermosetting epoxy resins, such as epoxyphenol resins, or polyester resins, for example, are suitable as resin components. Another type of lacquer contains thermoplastic materials in particle form in a solvent, in which they dissolve when the temperature rises, so that when the solvent is removed they form a continuous film with a suitably high melting point. One such type of product based on polyvinyl chloride is known as an organosol.

As heat-sealable materials, polyolefins are usually used in pure form or in a mixture with one another, such as polyethylene, polypropylene and mixtures thereof. The heat-sealable materials can be added to the thermally hardening or thermally layer-forming lacquer, e.g. in particle form.

A lacquer coating (including the heat-sealable layer) comprises epoxy and polypropylene, for example in an amount ratio of 80:20 to 95: 5, preferably 85:15 to 90:10, such as 88:12.

The strip 32 is usually a thermoplastic plastic that contains at least one polyolefin or consists of at least one polyolefin. Before ferred polyolefins are polyethylene, polypropylene and mixtures of the same, in particular a mixture of polypropylene and polyethylene with a melting point of about 150.degree. In special cases it can be advantageous to use modified polyolefins such as graft polymers and / or block polymers which, due to functional groups, optimize the adhesion to the cut edge 31, for example.

All materials that have to be melted on application should have a melting point which - if the lid is subjected to thermal sterilization - is at least 10 ° C, preferably at least 20 ° C above the sterilization temperature, for reasons the process economy should be as low as possible, ie at a sterilization temperature of approx. 130 ° C, preferably at approx. 150 ° C.

So that the tin and in particular the chromium layer is covered completely and pore-free, layer thicknesses for the primer from 5 to 15 μm, preferably from 7 to 12 μm and for the lacquer layer (including a heat-sealable layer) from 5 to 12 μm are provided preferably from 5 to 8 p advantageous.

The cover blanks 1 have, for example, a diameter of 11 cm. These blanks have already been preformed on their edge 6 by a processing machine, not shown, and the formation of the edge 6 is later used to attach the finished tear-off cover to a container or a can by means of a folded joint. This is known to the person skilled in the art and is not explained further here.

A conveying device 22 (Fig. 1), which conveys the lid blanks, the lid rings and the tear-off lid in the manufacturing device 20 along the transport path in the direction of arrow A from one processing station to the next processing station, is formed in particular by two toothed belts running in parallel, on which receptacles for the cover blanks or cover rings are provided, as is known to the person skilled in the art from WO 2006/017953 and is therefore not explained further here. At the respective processing stations, which are only shown schematically here, the blank cover to be processed is lifted from the conveyor device, processed by the processing station and returned to the conveyor device. This is indicated in the editing stations with arrows pointing up and down.

In a punching processing station (not shown ge) a cover ring 2 is first formed from the cover blank 1 by cutting a central part of the blank and discarding it as waste. This becomes the Removal opening 15 (see Fig. 6 or 7) of the later loading container formed, which is closed in a later manufacturing step with the tear-off film. Following the removal opening 15, there remains an initial flange 44 (see FIG. 2), which is further processed later. The metal material lies bare at the cutting edge 31 of the initial flange or the sheet metal of the cover ring 2 is no longer protected there by the coating. In a processing station 23, the edge of the initial flange 44 is pulled up to form a collar 4 with reference to FIG. 2. As can be seen from the synopsis of FIGS. 2 and 3, after this processing step the initial flange 44 is divided into two sections, which result from the drawing of the initial flange in a drawing station 24. A portion of the above-mentioned collar 4 and a further section having 7 gekennzeich ^¬ net and represents the sealing flange that is later than the upper surface ^¬ serves to Aufsiegelung the tear-off foil. Together, the two sections form a corner region 45, which is indicated in FIGS. 3a and 3b with the corresponding arrow. The collar 4 has an inner side 40 of the collar facing the removal opening and an outer side 41a of the collar facing away from the removal opening, and the cover blank 1, the cover ring 2 and the tear-off cover 10 have an outer side 7, 40 and an inner side 41a, 41b of the cover. In the corner region 45 in Fig. 3a a strip 32 is shown which is ring-shaped with respect to the circumference of the cover ring and is essentially triangular in cross-section, and in Fig. 3b is a strip 32 which is ring-shaped with respect to the circumference of the cover ring, is essentially L-shaped in cross-section, Stripe 32 shown.

As already described above, the ringför-shaped strip 32 is made of thermoplastic material and bil det in the later curling of the collar 4 a sealing device for the cut edge 31, which will be described below. The application of the annular strip 32 according to the invention is carried out by applying molten, liquid plastic material in an application station 24a (according to the third processing station), which is arranged between the drawing station 24 and a rolling station 25, by means of an application nozzle 3, what in Fig. 4 is shown. Accordingly, the application nozzle 3 comprises an outlet opening 3a which is designed in terms of shape such that the annular strip 32 fills the corner area 45 and is thus essentially triangular, which can be seen in FIG. 3a. With reference to FIG. 3b, the outlet opening can, for example, also be shaped in such a way that the annular strip 32 is applied in a substantially uniform thickness d2 over its entire width. In this context, "width" is understood to mean the sum of the two strip legs S1 and S2 shown in FIG. 3b. The length of the two legs S1 and S2 need not be the same in both embodiments from FIGS. 3a and 3b and it can in each case vary, depending on the dimensions (diameter) of the tear-off cover to be produced or depending on the size ratios between the removal opening and the ring width of the cover ring. In the context of FIGS that has a larger / smaller and / or differently shaped exit opening.

In the embodiment from FIG. 3b, the strip 32 preferably has a thickness d2 in the range from 0.05 millimeters to 0.5 millimeters, preferably a thickness of approximately 0.1 millimeters.

The application station 24a comprises a spacer element (not shown) to maintain an essentially constant distance between the application nozzle 3 and the outside 41a of the collar 4, so that the annular strip 32 in the triangular embodiment (Fig. 3a) an im Essentially constant maximum thickness dl, in particular a maximum thickness dl of 0.4 mm, over its entire length and, in the embodiment from FIG. 3b, in addition to its essentially constant thickness d2 over its entire width, also has an essentially uniform thickness d2 over its entire length. The length here denotes the total circumference of the annular strip. The term “fully” in this text also refers to this. During application, care is therefore taken that the distance between the outlet opening 3a remains essentially constant when the liquid plastic is applied, so that the thickness d2 or the maximum thickness dl of the strip 32 is essentially constant and the strip can be made thin. This can be done, for example, in that the cover ring 2 is precisely centered on a receptacle in the processing station 29 and the application nozzle 3 with the outlet opening is at a defined distance from this receptacle Transfer from the conveyor with a subsequent centering takes time, however, so that for the very high manufacturing cadences that are aimed for, it is preferred that the cover ring in the processing station is pressed with the collar outside 41a against a roller that is precisely positioned with respect to the nozzle position during application is, whereby the distance between the application nozzle z ur collar outside 41a is precisely defined in a simple manner.

The application nozzle 3 is preferably stationary in egg ner application position for the annular strip 32. The cover ring is moved in a rotating manner in the processing station 29 and the outside of the collar 41a is moved past the outlet opening 3a of the application nozzle in order to apply the plastic in liquid form to the rotating cover ring via the application nozzle 3. Alternatively, the application nozzle could be moved around the cover ring while the cover ring would keep stationary ge. However, this alternative is not preferred, as compliance with the required strip thickness would be more difficult and the process would take longer.

In a preferred embodiment, the application station 24a comprises a pivot element (not shown) for pivoting the cover ring 2 from a Zuführungspo position in which the cover ring can be guided into the application station (usually horizontal), into the Aufbringpo position, and back. Depending on the embodiment of the application station, it may be advantageous to move the cover ring from its horizontal position in FIG. 3a or 3b to an inclined position so that the application nozzle can more easily get to the corner area 45. Of course, an application in the horizontal position of the cover ring is also possible, as is shown in FIG.

The processing station 29 comprises a heated supply line and a heated and controllable valve (not shown), wherein the application nozzle 3 can be supplied via the valve with the melted plastic, which passes through the channel 3b to the application opening 3a. In this context, it is noted that application is preferably understood here as application and not as spraying. In this way, a shape-related better defined strip is achieved.

The cover ring 2 is thus raised at the processing station 29, possibly pivoted, rotated ver and the application is activated when the cover ring has reached the correct position relative to the outlet opening 3 a of the application nozzle 3. After at least one full rotation, when a continuous strip is formed in the corner area 45, the cover ring with the strip 32 is moved back down to the conveyor device, the rotation being stopped so that the cover ring is placed back onto the receptacles of the conveyor device 22 can be. The cover ring can be rotated at high speed during the application of the thin plastic strip, including a rotation with more than 200 revolutions per minute is understood. A preferred speed of rotation is in the range from 400 to 600 per minute.

After the application of the annular strip 32, it is conveyed to the roll-in station 25. The plastic of the strip 32 cools down as soon as it is applied to the lid ring and solidifies, so that the plastic does not flow during further conveyance and the strip in the in Fig. 3a or 3b shape shown is stable. At most, a coolant, for example in the form of a fan, can be provided in the application station 24a or processing station 29.

In the embodiments shown in FIGS. 3a and 3b (or beforehand in a separate step) at the upper free end of the collar 4, a curvature (also called "precurl") outwards (away from the removal opening) has been produced, which the In an embodiment with retort-curl (not shown) this curvature points inwards accordingly (towards the removal opening). In the curling station 25, the curling is carried out upwards and towards the outside of the collar 41a. The directional indication "upwards" relates to the position of the cover ring shown in FIGS. 2 and 3 (the intended top of the cover ring in these figures pointing downwards). When the reverse curl is formed, the strip 32 forms a seal which prevents liquid from entering the interior of the reverse curl. Thus, the bare cut edge 31 is protected against the influence of a liquid in the later container. It does not matter whether the curling takes place in such a way that the cut edge 31 is partially embedded in the band 32 or whether it only lies against the band 32. Even the opposite, that the cut edge 31 cuts through the band 32 and rests on the metal of the collar outer side 41a, does not interfere with the function of the strip 32. In one embodiment, however, it is preferred if the cut edge 31 is within the reverse curls is as shown in FIG. In any case, it is only important that the curl is in full contact with the strip 32 and thus a sealing effect is achieved. This full contact is brought about with regard to the pressure of the curling on the ring-shaped strip in such a way that the seal withstands subsequent sterilization (typically 60 min. At 121 ° C.). The seal also ensures that none of the contents of the container to be closed with the tear-off lid come into contact with the unprotected cut edge. The curl that forms the edge of the removal opening ensures that the user of the container is protected from the sharp-edged cut edge when removing the contents.

The previous manufacturing steps have been carried out in a position in which the linge Deckelroh ^¬ and cover rings were side with their subsequent upper ^¬ or sorted with the sealing flange 7 facing down on as mentioned. This is the preferred embodiment also in the present invention, although the lid blanks or lid rings could also be transported upside down if this would be expedient. As mentioned, the blank or the ring is lifted off the conveyor in the individual processing stations 23, 24, 24a, 29 and 25, processed and put back again, whereupon the conveyor carries out conveying steps which take the lid blanks or lid rings to the next processing station leads.

In embodiments of the invention, the curl is heated in order to at least partially melt the strip 32 at least in the contact area to the metal of the lid or the coatings located thereon and thus to establish a good connection, which will be explained below.

In a first exemplary embodiment, it is a processing station 35 in front of the turning station 26 is provided, in which processing station 35 the heating of the curling takes place. This can be carried out in such a way that the cover is also lifted off the conveyor 22 at this processing station 35, followed by heating in the processing station 35 and then placing it on the conveyor. The cover ring or its curling can, however, also be heated in the processing station 35 while it is located on the conveying means 22, that is to say without being lifted off the conveying means. In the processing station 35 in front of the turning station, the cover ring is still facing up with the curl. This enables heating from above. For this purpose, an induction heating device is preferably provided in the processing station 35. The design of such a Heizeinrich device is known to the person skilled in the art and need not be explained in more detail here. Instead of an induction heating device, an infrared radiation source or a hot air source could also be provided.

In another exemplary embodiment, the processing station for heating the roll-up can be provided after the turning station and is shown in the example shown as processing station 35 '. In this processing station 35 'the curling is at the bottom and accordingly it is preferred if the heat source acts from below, so that it may be more advantageous to design the processing station 35' so that the cover ring 2 is lifted from the conveyor 22 in it to carry out the processing with the heating source. In this case too, induction heating or another type of heating can be provided.

After the curling has been heated, cooling can be provided, for example by means of a fan. This is particularly advantageous if the processing station 35 ′ is present after the turning station 26 and a presealing station 27 is also provided for presealing the tear-open film on the sealing flange 7. Otherwise, heating up the curl can lead to a undesired influence on the temperature for the preseal gel.

As an alternative to heating in a processing station 35 or 35 'or in addition to this, the heating of the curling can be provided in a sealing station, which is preferably divided into a pre-sealing station 27 and a main sealing station 28.

If the manufacturing steps are carried out with the sealing flange 7 pointing downwards, the cover ring is now turned in the turning station 26, so that during further processing the sealing flange 7 is at the top in the conveyor 22 and in the processing stations after the turning station. Fig. 5 shows this position, which corresponds to the intended use of the tear-open cover. In this position, the cover ring is thus conveyed into the sealing station, in which the tear-open film is sealed over the removal opening 15. The tear-off film is completely sealed onto the area shown by arrow 7. This takes place in two stages with the pre-sealing station 27 and the main sealing station 28. The sealing process is also known to the person skilled in the art and is not explained further here. Further processing stations can follow in which the sealing film is embossed, the tear-off tab is positioned and a leak test is carried out. This is also known to the person skilled in the art and is not explained further here.

At the end of the manufacturing device 20 fer term tear-off lids 10 are issued, the removal opening 15 of which is spanned by a tear-off film (not shown) which is sealed on the sealing flange 7.

From a synopsis of Fig. 6, which shows a tear-off lid 10a with retort curl, and FIG. 7, which shows a tear-off lid 10 with reverse curl, the difference can be seen that with retort curl the curling with the annular strip 32 is visible from above when the tear-off film is pulled from the removal opening 15. In contrast, the solution with the reverse curl, the curl and the strip 32 are not visible, since in this view they have been carried out downwards and towards the outside of the collar 41a. Apart from the fact that this results in a better appearance for the consumer, the solution with reverse-curl has the important advantage that no product can collect between the roll and the tear-off film.

While preferred embodiments of the invention are described in the present application, it should be clearly pointed out that the invention is not restricted to these and can also be carried out in other ways within the scope of the following claims. Terms used in the description such as “preferred”, “in particular”, “advantageous”, etc. relate only to optional and exemplary embodiments.

Claims

1. A method for producing tear-open covers (10), in which

- a sheet or a blank cover (1) punched out of it made of tinplate or tin-free steel (Tin Free Steel or TFS) is treated on both sides with at least one lacquer in such a way that both sides have a lacquer layer that is more similar, preferably the same polarity,

- A cover ring (2) with a central Ent receiving opening (15) is formed from the cover blank (1) by punching, which is surrounded by an initial flange (44);

- A sealing flange (7) and a collar (4) protruding away from the sealing flange (7) are formed from the initial flange (44) by drawing, which together form a corner region (45);

- On the collar (4), a ring-shaped strip (32) made of a thermoplastic material compatible with the at least one layer of lacquer on an outer side of the collar (41a) facing away from the removal opening (15) or on an inner side of the collar (40) facing the removal opening is applied;

- The collar (4) is rolled up at its free end (31) to the outside of the collar (41a) or to the inside of the collar (40) until the roll (33) comes fully into contact with the annular strip (32) and

- A tear-off film is sealed onto a sealing surface of the sealing flange (7).

2. The method according to claim 1, wherein the sheet metal or the blank cover punched therefrom (1) prior to the application of the lacquer layer one the adhesion of the Lacquer layer improving step, in particular a primer was subjected.

3. The method according to claim 1 or 2, in the case of which

- In the corner area (45) a ring-shaped strip (32) made of plastic by means of an application nozzle (3) is applied to one of the removal opening (15) from the outer side of the collar (41a) facing away;

- The collar (4) is rolled up at its free end (31) towards the outside of the collar (41a) until the roll-up (33) comes into full contact with the ring-shaped strip (32);

- A tear-off film is sealed on a sealing surface of the sealing flange (7).

4. The method according to any one of the preceding claims, wherein an outlet opening (3a) of the application nozzle (3) for the plastic is shaped related to the shape so that the annular strip (32) has a substantially uniform thickness (d2) over its ge entire width is applied, in particular applied, or that the annular strip (32) is applied, in particular applied, in such a way that it fills the corner region (45) essentially in a triangular cross-section.

5. The method according to any one of the preceding claims, wherein when applying the distance between the application nozzle (3) and the cover ring (2) is kept constant ge, so that the annular strip (32) with a substantially uniform thickness (d2) over its entire length is applied, in particular applied, or is applied with an essentially constant maximum thickness (dl) over its entire length, in particular is applied.

6. The method according to any one of the preceding claims, wherein the cover ring (2) in a horizontal position, in particular with the sealing surface of the Siegelflan cal (7) pointing downward, is brought up to the application nozzle (3), and before the application of the ringförmi gene strip (32) is pivoted from the horizontal position into an inclined position until the outlet opening (3a) of the application nozzle (3) is properly aligned on the Eckbe rich (45) or on the inside of the collar (40), and when the cover ring is applied (2) is rotated around its axis in the inclined position, while the application nozzle (3) is held stationary.

7. The method according to any one of the preceding claims, wherein the lid ring on its lid outer side (7, 40) at least in the area of the sealing flange (7) and the collar (4) has a coating that is heat-sealable with a contact side of the tear-off film and wherein the inside of the lid (41a, 41b) has a coating that is compatible with the filling material and has a similar or the same polarity as the coating of the outside of the lid (7, 40).

8. The method according to any one of the preceding claims, wherein the cover ring has a primer layer improving the adhesion of the paint layer under the paint.

9. The method according to any one of the preceding claims, wherein the annular strip (32) is applied by applying a melted, liquefied thermoplastic plastic, the ther moplastic plastic on the paint layer of the lid outer side (7, 40) and the Lacquer layer on the inside of the lid (41a, 41b) and on the cut edge (31) adheres and in particular where the plastic contains at least one polyolefin or consists of at least one polyolefin, in particular special polyethylene and / or polypropylene.

10. Device (20) for producing tear-off lids (10) by means of the method according to one of the preceding claims, in which tear-open lids (10) each have a tear-off foil on a sealing surface (7) arranged around a removal opening (15) , wherein the device (20) comprises a conveying device (22) for lid blanks (1), lid rings (2) and tear-off lid (10) as well as processing stations (23-28) which follow one another in the conveying direction (A) for processing the lid blanks , Lid rings and tear-off lid are provided, with a first processing station as a punching station for the formation of a lid ring (2) from a lid blank (1), a second processing station (23) for forming the collar (4), a third processing station (24a) for On bringing the annular strip (32) to the cover ring (2) are provided and a fourth processing station (25) is provided for rolling the collar, wel che de is designed so that the curl (33) comes into contact with the annular strip (32), and further at least one sealing station (27, 28) is provided, which is designed to seal a tear-off film on the sealing surface (7), characterized thereby net that the annular strip (32) can be applied, in particular can be applied, on an outer side of the collar (41a) facing away from the removal opening (15) in the corner region (45) of the collar (4) or on an inner side of the collar (40), and that the The collar (4) can be rolled up towards the outside of the collar (41a) or towards the inside of the collar (40).

11. The device according to claim 10, wherein the third processing station (24a) for applying the annular strip (32) made of plastic includes an application nozzle (3) with an outlet opening (3a), which outlet opening (3a) is designed in terms of shape in such a way that the annular strip (32) has a substantially uniform thickness (d2) over its ge entire width is applied, or that the ring-shaped strip (32) is essentially triangular in cross-section, and the third processing station (24a) has a spacer element for maintaining an essentially constant distance between the application nozzle (3) and the cover ring ( 2), so that the ring-shaped strip (32) has an essentially uniform thickness (d2) over its entire length, in particular with a thickness (d2) in the range from 0.05 mm to 0.5 mm, preferably with a thickness of approx. 0.1 mm, or so that the annular strip (32) has an essentially uniform maximum thickness (dl) over its entire length.

12. Device according to one of claims 10 or 11, wherein the application nozzle (3) is statio när in an on-bringing position for the annular strip (32), the third processing station (24a) having a receptacle for a cover ring that can be rotated by means of a drive. 2) in order to apply the plastic in liquid form to the rotating drivable cover ring (2) via the application nozzle.

13. The device according to claim 12, wherein the third processing station (24a) is a pivot element for pivoting the cover ring (2) from a position Zuführungspo in which the cover ring (2) in the third processing station (24a) can be introduced into the Aufbringposi tion , and back, includes.

14. Device according to one of claims 10 to 13, wherein the third processing station (24a) a heated supply line and a heated and controllable valve, wherein the application nozzle (3) can be supplied with the melted plastic via the valve.

15. Tear-open lid (10) made of tinplate or tin-free steel (TFS) provided on both sides with a layer of lacquer, comprising a circumferential fastening section (6), a sealing flange (7) with a tear-off film sealed on this and a sealing flange (7) around the circumferential rolled-up collar (4) which forms a corner area (45) with the sealing flange (7) and which laterally delimits the removal opening (15), the collar (4) facing away from the collar outer side (41a) or the removal opening (15) is rolled in towards an inner side of the collar (40) facing the removal opening, and is further characterized by an annular strip (32) applied, in particular applied, to the outer side of the collar (41a) in the corner area (45) or to the inner side (40) of the collar, made of thermoplastic synthetic material, which annular strip (32) is fully in sealing contact with the outwardly or inwardly rolled collar (33) and wherein the Lac The layer on the outside of the cover (7, 40) and the layer of varnish on the inside of the cover (41a, 41b) at least in the area of the sealing flange (7) and the collar (4) have similar or the same polarity and the strip (32) made of thermoplastic material with the lacquer layer on the outside of the cover (7, 40) and with the layer of lacquer on the inside of the cover (41a,

41b) and is compatible with the metal of the cut edge (31), ie adheres well to it, in particular a thermoplastic plastic which contains at least one polyolefin or consists of at least one polyolefin, especially preferably polyethylene and / or polypropylene.

16. A tear-off lid (10) according to claim 15, where the collar (4) is rolled up to one of the removal opening (15) from the outer side of the collar (41a) facing away, and is further characterized by one on the outer side of the collar (41a) in the corner area ( 45) applied, in particular applied, annular strips (32).