Lid attachment for metal can and method of attaching a lid to a metal can

Abstract

 The invention relates to a lid attachment for a metal can (400) having an open upper end with a flange (410) forming an annular upper face (411) and an outwardly curved flange edge (412), wherein the lid attachment comprises a unitary plastic part (100) comprising a snap-on ring (105) with an abutment surface (101) and a sealing surface (102) and an adhesive applied to the sealing surface wherein an axial distance between the abutment surface and the sealing surface corresponds to the axial distance between the flange edge and the upper face of the metal can wherein the lid attachment is designed for such that the abutment surface initially expands when the lid attachment is attached to a can and the abutment surface springs back behind the flange edge when fully attached. The invention further relates to a method of attaching a lid to a metal can.

Description

[0001] The invention relates to a lid attachment for a metal can. The invention further relates to a method of attaching a lid to a metal can. Particularly, a lid attachment for a metal beverage can and a method for attaching a lid to a metal beverage can are provided.

[0002] Lid attachments for metal cans, particularly metal beverage cans, usually comprise a metal lid that is secured to the metal can via a double seam. However, manufacturing of this double seam is complex, time-consuming and expensive.

[0003] It is also known to provide lid attachments comprising plastic materials from US 4,236,629, US 4,568,006, EP 0 320 808 A1 and EP 0 779 227 A1. However, the solutions disclosed in these documents are at least as complex, time-consuming and expensive to manufacture as the known metal to metal lid attachments using a double seam. Further lid attachments comprising plastic materials are known from EP 0 620 160 A2, WO 2007/015752 A2, US 2008/0290105 A1 and WO 2009/060207 A1. The solutions disclosed in these documents show different kinds of projections on the outer periphery of the upper end of the can. But these projections are also complex, time-consuming and expensive to manufacture and are further not suitable for thin-walled contemporary metal beverage cans.

[0004] It is therefore an objective of the present invention to provide a lid attachment for a metal can, a metal can and a method of attaching a lid to a metal can that avoid or at least reduce one or more of the above mentioned disadvantages. It is further an object of the present invention to provide a lid attachment for a metal can, a metal can and a method of attaching a lid to a metal can that are suitable for thin-walled metal cans for storing carbonated beverages.

[0005] According to a first aspect of the invention, a lid attachment for a metal can is provided having an open upper end with a flange forming an annular upper face and exhibiting an outwardly curved flange edge that has an axial distance from the upper face measured in an axial direction of the metal can, wherein the lid attachment comprises a unitary plastic part and an adhesive, wherein the unitary plastic part comprises a hook-shaped annular snap-on ring with an upwardly facing abutment surface and a downwardly facing sealing surface, wherein an axial distance between the abutment surface and the sealing surface corresponds to the axial distance between the flange edge and the upper face of the metal can, wherein the lid attachment is designed for such that the hook-shaped annular snap-on ring upwardly facing abutment surface initially expands when the lid attachment is attached to a can and the upwardly facing abutment surface of the annular snap-on ring springs back behind the flange edge when fully attached to a can, and wherein the adhesive is applied to the sealing surface.

[0006] The lid attachment according to the present invention comprises a unitary plastic part which is meant to be a one-piece-element made of plastic material. Preferably, the unitary plastic part is formed using injection molding. The provision of such a unitary plastic part has the advantage that fewer parts need to be handled during assembly of the lid attachment and the open upper end of the metal can, resulting in a manufacturing and assembly process that is less complex, time- and cost-intensive.

[0007] To further facilitate the assembly of the lid attachment and the open upper end of the metal can the invention provides for a hook-shaped annular snap-on ring with an upwardly facing abutment surface, i.e. a ring-shaped part of the unitary plastic part that is flexible enough to slip over the diameter of the outwardly curved flange of the open upper end of the can while being pushed over the upper end of the can in axial direction of the metal can during assembly. When the hook-shaped annular snap-on-ring with the upwardly facing abutment surface has passed the outwardly curved flange edge during assembly, this ring-shaped element of the unitary plastic part shows resilient characteristics and moves back into a shape with a diameter smaller than the upwardly curved flange edge. This allows for an time- and cost-efficient production process of the unitary plastic part as well as a time- and cost-efficient assembly process of the lid attachment and the open upper end of the can, since a linear process pushing the lid attachment and the can against each other in axial direction of the can is sufficient rather than a process involving rotation of the can for forming a double seam.

[0008] Since according to the invention the axial extension of the outwardly curved flange, i.e. the distance from the outwardly curved flange edge to the annular upper face, and the axial extension of that part of the unitary plastic part between the sealing surface and the upwardly facing abutment surface correspond, the lid attachment and the open upper end of the metal form a positive fitting after assembly suitable to withstand an internal pressure in a can containing beverages, different kinds of food etc., particularly an internal pressure of up to 6.2 bar in a metal can containing carbonated beverages.

[0009] In addition to this positive fit between the lid attachment and the open upper end of the metal can an adhesive bond between the two parts is provided for, more precisely between the sealing surface of the hook-shaped annular snap-on ring and the annular upper face of the flange of the open upper end of the metal can. This further increases the bond strength between the lid attachment and the can in order to provide for an arrangement able to withstand internal pressure due to storage of carbonated beverages in the can.

[0010] A further advantage of the present invention is hat the upper end of a metal can receiving the lid attachment according to the present invention can be shaped as a flange projecting outwardly and downwardly with respect to the opening defined by the open upper end of the can. In order to form the inventive shape of a flange with an annular upper face and an outwardly curved flange and with an axial distance from the annular upper face in axial direction of the metal can, the open upper end of the metal can is curled. Thus the can can be produced easily and time- and cost saving without significant changes to the can manufacturing process.

[0011] The invention may be improved in that an inner diameter of the snap-on ring is smaller than a diameter of a flange edge of a metal can the lid attachment is adapted for.

[0012] According to this embodiment the unitary plastic part, particularly the hook-shaped annular snap-on ring, is flexible enough to expand such that the inner diameter of the snap-on ring in a non-expanded state can be enlarged to a diameter of at least the extension of the diameter of the flange edge during assembly.

[0013] The invention may be improved in that the axial distance between the abutment surface and the sealing surface is slightly larger than the axial distance between the flange edge and the upper face of a metal can the lid attachment is designed for. This embodiment may be an addition or an alternative to the previously described embodiments.

[0014] According to this embodiment, the axial distance between the abutment surface and the sealing surface does not correspond exactly to the axial distance between the flange edge and the upper face of a metal can the lid attachment is designed for. In this case, a clearance in the positive fit between the lid attachment and the metal can may occur. This embodiment is particularly preferred in cases where an additional adhesive bond is provided for between the sealing surface and the upper face, particularly an adhesive bond as described with respect with the following embodiments.

[0015] The invention may be improved in that the adhesive includes an activation mechanism that activates an adhesive effect and/or an increase in volume of the adhesive in the presence of an activation trigger, wherein the activation trigger is pressure and/or air and/or moisture and/or heat and and/or a contact of at least two adhesive components and/or an absence of air. It is further preferred that the adhesive includes an expansive material and/or a material sensitive to pressure and/or air and/or moisture and/or heat and and/or a contact of another adhesive components and/or an absence of air.

[0016] To provide for the adhesive bond between the sealing surface of the lid attachment and the upper face of the metal can it is preferred that the adhesive material only exhibits its adhesive characteristics after it is activated. This has the advantage, that the adhesive can be applied in an early stage of the production or assembly process without causing problems due to the adhesive characteristics. These characteristics are preferably only activated in a stage of the process where the adhesive effect is desired.

[0017] This activation of the adhesive can be initiated by one or more of the following activation triggers: One activation trigger may be pressure that is applied to the adhesive. In this case, the adhesive preferably is microencapsulated such that the microcapsules brake when a certain pressure is applied. Preferably, the pressure needed for activating the adhesive corresponds to a pressure occurring during the assembly of the lid attachment to the open upper end of the metal can. Alternatively or in addition the adhesive might be of cyanoacrylate-type that is activated by the presence of air and/or moisture. A further activation trigger might be the contact between two adhesive components that leads to a chemical reaction between the two components, e.g. a 2K-epoxy-adhesive. Further still, an adhesive material might be activated by a heat source leading to a chemical reaction of the adhesive material (e.g. 1K-epoxy-adhesive). A heat source may activate an adhesive material also by melting e.g. hot melt adhesives or meltable plastic adhesives. Further still, also the lack of air can be a preferred activation trigger for e.g. anaerobic adhesives. It is preferred that the material of the adhesive is adapted to the kind of activation trigger used.

[0018] Further, it is preferred to provide an adhesive material that has an expansive effect. In this embodiment it is preferred that the activation trigger initiates the expansion of the extensive material. The provision of an expansive material has the advantage that this expansive material will fill up possible gaps between the lid attachment and the open upper end of the can when activated and thus provide for a particularly tight seal between the lid attachment and the open upper end of the can.

[0019] The invention can be improved in that the lid attachment, particularly the adhesive, is designed for a permanent fixation of the lid attachment, particularly the unitary plastic part, to a can.

[0020] The provision for a permanent fixation of the lid attachment to the open upper end of the can, i.e. a non-removable attachment of the lid to the open upper end of the metal can, is particularly preferred because of the advantage that the fixing of the lid attachment to the open upper end of the metal can is permanent in a sense that during the general lifetime of a beverage can and during common handling conditions the lid attachment cannot be removed from the open upper end of the can applying common forces that apply during handling, transport, storage and sales or intended use of the beverage can.

[0021] The invention can be further improved in that the lid attachment and the flange are designed for such that the outwardly curved flange edge initially is compressed when the lid attachment is attached to a can and springs back behind the upwardly facing abutment surface of the annular snap-on ring when it is fully attached to a can.

[0022] This embodiment is preferred in order to reduce or eliminate the requirement of flexibility of the hook-shaped annular snap-on ring of the unitary plastic part of the lid attachment. When the outwardly curved flange edge is flexible in that it can be compressed during assembly of the lid attachment, the upwardly abutment surface of the annular snap-on ring needs to expand less or not at all while the annular snap-on ring is being pushed over the outwardly curved flange during the assembly process. In order to provide for a positive fit between the lid attachment and the open upper end of the can, the outwardly curved flange edge is resilient and moves back into its un-deformed shape after the upwardly faced abutment surface of the annular snap-on ring has passed the outwardly curved flange edge.

[0023] This embodiment allows for a balanced design of the outwardly curved flange edge and the annular snap-on ring with the upwardly faced abutment surface and the respective materials of the flange and the snap-on ring in order to provide the actual combination of flexibility and resilience in the two parts required for the inventive engagement and positive fit in the assembled state as well as for an easy push-on assembly process.

[0024] The invention can be further improved in that the lid attachment further comprises a cap designed for closing an opening defined by the unitary plastic part.

[0025] In order to access the contents of the metal can, particularly a beverage contained in a metal beverage can, the lid attachment includes a cap in addition to the unitary plastic part. The cap closes an opening in the unitary plastic part during handling, transport and storage of the metal can. During intended use of the metal can, its contents need to be accessed and therefore the cap is designed to be at least partly detached from the opening during intended use. The cap may be fully removed or still be connected to the unitary plastic part after opening. Further, the cap might be a reselable cap i.e. the cap might be designed to open and close the opening defined by the unitary plastic part more than once. The cap may comprise metal or plastic material or consist thereof. For example, the cap may comprise alloys of aluminum, steel etc.

[0026] This embodiment has the advantage that only the unitary plastic part needs to be specifically designed to engage with the open upper end of the metal can. The cap, however only engages with the unitary plastic part and thus a variety of caps designed for different purposes can be fitted onto one design of the unitary plastic part. Thus, the assembly process of the lid attachment with the engagement of the unitary plastic part and the open upper end of the can can remain unchanged or nearly unchanged while at the same time providing for a variety of different opening mechanisms of the can.

[0027] The invention can be further improved in that the unitary plastic part comprises a downwardly facing second abutment surface designed for engaging with the cap.

[0028] In a particularly preferred embodiment the unitary plastic part is fitted with a second abutment service for a positive fit with the cap. A particularly preferred embodiment provides for a flexible cap with an annular cap ring with a diameter smaller than the diameter of the downwardly facing second abutment surface of the unitary plastic part, wherein the annular cap ring initially expands when the cap is attached to the unitary plastic part and the annular cap ring springs back behind the downwardly facing second abutment surface of the unitary plastic part when the cap is fully attached to the unitary plastic part. In this way a time- and cost-efficient procedure to assemble the cap and the unitary plastic part can be provided by pushing both parts relatively against each other.

[0029] The assembly of the cap and the unitary plastic part as well as the assembly of the unitary plastic part and the open upper end of the can can be realized in the same or succeeding assembly process steps. Alternatively, it can be preferred to assemble the cap and the unitary plastic part separately and provide a lid attachment of the cap already assembled to the unitary plastic part to the further process of assembling this pre-assembled lid attachment to the open upper end of the can.

[0030] According to a further aspect to the invention, a metal can is provided having an open upper end with a flange forming an annular upper face and exhibiting an outwardly curved flange edge that has an axial distance from the upper face measured in an axial direction of the metal can, characterized in that the metal can comprises a lid attachment according to the invention as described herein.

[0031] According to a further aspect of the invention, a method of attaching a metal lid to a metal can is provided comprising the steps providing a metal can having an open upper end with a flange forming an annular upper face and exhibiting an outwardly curved flange edge that has an axial distance from the upper face measured in an axial direction of the metal can, providing a lid attachment comprising a unitary plastic part with a hook-shaped annular snap-on ring with an upwardly facing abutment surface and a downwardly facing sealing surface wherein an axial distance between the abutment surface and the sealing surface corresponds to the axial distance between the flange edge and the upper face of the metal can, applying an adhesive to the sealing surface, attaching the lid attachment to the metal can wherein the hook-shaped annular snap-on ring upwardly facing abutment surface initially expands and the upwardly facing abutment surface of the annular snap-on ring springs back behind the flange edge when fully attached to a can.

[0032] The method according to the invention can be improved in that attaching the lid attachment to the metal can comprises that the outwardly curved flange edge initially is compressed when the lid attachment is attached to a can and springs back behind the upwardly facing abutment surface of the annular snap-on ring when it is fully attached to a can.

[0033] The method according to the invention can be further improved by the step activating an adhesive effect and/or an increase in volume of the adhesive in the presence of an activation trigger, wherein the activation trigger is pressure and/or air and/or moisture and/or heat and and/or a contact of at least two adhesive components and/or an absence of air.

[0034] The method according to the invention can be further improved by the step providing a permanent fixation of the lid attachment, particularly the unitary plastic part, preferably via the adhesive, to a can.

[0035] The method according to the invention can be further improved by the step attaching a cap to the unitary plastic part such that the cap closes an opening defined by the unitary plastic part, wherein preferably the cap engages with a downwardly facing second abutment surface of the unitary plastic part.

[0036] As to the advantages, preferred embodiments in details of these further aspects and preferred embodiments, reference is made to the corresponding aspects and embodiments described above.

[0037] Preferred embodiments of the invention shall now be described with reference to the attached drawings in which

Fig. 1:

shows a part of a cross-section of an open upper end of a metal can according to the state of the art,

Fig. 2:

shows a part of a cross-section of an open upper end of a metal can according to the present invention,

Fig. 3:

shows different alternative embodiments to the open upper end of a metal can shown in Fig. 2,

Fig. 4:

shows a cross-section of a lid attachment attached to the open upper end of a metal can according to the present invention,

Fig. 5:

shows an enlarged view of detail "D" in Fig. 4,

Fig. 6-8:

show different embodiments of the flange of an open upper end of a metal can and of the annular snap-on ring of the lid attachment,

Fig. 9:

shows an exemplary embodiment of a lid attachment with a mouthpiece.

[0038] State of the art lid attachments for open upper ends of metal cans regularly involve a metal lid that is secured to the upper end of a can via a double-seam. The open upper end, or neck, of a metal can 900 according to the state of the art as depicted in Fig. 1 therefore has a slightly outwardly curved flange 901.

[0039] As can be seen from Fig. 2, according to the invention the flange 410 of the open upper end of a metal can 400 differs from the state of the art in that the flange 410 according to the invention has an annular upper face 411 with a radial extension S and an outwardly curved flange edge 412 that has an axial distance A from the upper face 411 measured in an axial direction of the metal can 400.

[0040] Fig. 3 depicts a variety of alternatives of flanges 410a-I according to the present invention. The details and advantages described herein apply accordingly to a variety of different flanges as exemplary depicted fig 3.

[0041] The flange 410 provides for easy, time- and cost-saving manufacturing on the one hand and, as will be understood from the following description with respect to the lid attachment 1 and its engagement with the flange 410 of the open upper end of a metal can 400, it also provides for a secure positive fit with the lid attachment 1 suitable for carbonated drinks as well as a time- and cost-saving assembly with the lid attachment 1.

[0042] Fig. 4 depicts a lid attachment 1 according to the present invention including a unitary plastic part 100 attached to the open upper end of a metal can 400 and including a cap 300. Details with respect to the engagement of unitary plastic part 100 and open upper end of a metal can 400 as well as cap 300 after assembly are depicted in fig. 5.

[0043] The lid attachment 1 comprises a unitary plastic part 100 with a hook-shaped annular snap-on ring 105 with an upwardly facing abutment surface 101 and a downwardly facing sealing surface 102. An axial distance between the abutment surface 101 and the sealing surface 102 corresponds to the axial distance (A as depicted in fig. 2) between the flange edge 412 and the upper face 411 of the metal can 400. During assembly the hook-shaped annular snap-on ring 105 upwardly facing abutment surface 101 initially expands when the lid attachment 1 is pushed over the flange 410 of the can 400. In the assembled state shown in fig. 5, the upwardly facing abutment surface 101 of the annular snap-on ring 105 springs back behind the flange edge 412.

[0044] As can be further seen from fig. 5, the axial distance between the abutment surface 101 and the sealing surface 102 is slightly larger than the axial distance (A as depicted in fig. 2) between the flange edge 412 and the upper face 411 of a metal can 400 the lid attachment 1 is designed for. The resulting gap is preferably filled by an adhesive 201, 202, 203a, b as depicted in fig. 6-8.

[0045] It is further preferred, that outwardly curved flange edge 412 initially is compressed when the lid attachment 1 is attached to a can 400 and springs back behind the upwardly facing abutment surface 101 of the annular snap-on ring 105 when the lid attachment 1 is fully attached to the can 400 as shown in fig. 5.

[0046] The embodiment shown in fig. 4 and 5 further comprises a cap 300 designed for closing an opening 600 defined by the unitary plastic part 100. For engagement with the cap 300 the unitary plastic part 100 comprises a downwardly facing second abutment surface 103. The cap 300 comprises a removable top part 301 and a tamper evidence ring 302. The type of tamper evidence element shown in this embodiment is an example only and may be realized using other options and designs. Prior to use oft he can 400, i.e. prior to opening of the can 400, the top part 301 and the tamper evidence ring 302 are connected via one or several breakable straps 303. The cap 300 can be removed from the unitary plastic part 100 preferably by twisting the top part 301 along a thread 500. Since the tamper evidence ring 302 is engaged with the downwardly facing second abutment surface 103, the straps 300 break on the first opening of the can 400 while the tamper evidence ring 302 stays on the can 400 and the only top part 301 of the cap 300 is removed. It is further preferred that the can is reclosable or resealable, i.e. that the top part 301 can be replaced to close the opening 600 defined by the unitary plastic part 100 again.

[0047] Further, it is preferred that the cap 300, particularly the tamper evidence ring 302, is flexible enough to be pushed over the downwardly facing second abutment surface 103 during assembly of the lid attachment 1. This allows for an easy production of the cap 300 since the top part 301, the tamper evidence ring 302 and the straps 303 can be manufactured as one piece and assembled with the unitary plastic part 100 by pushing the cap 300 and the unitary plastic part 100 gainst each other. The top part 301 of the 300 cap may comprise different solutions regarding mouthpieces, reclosable mechanisms and the like.

[0048] Fig. 6-8 depict three different exemplary embodiments of the upwardly facing abutment surface 101 of the unitary plastic part, the downwardly curved flange edge 412, and an adhesive 201, 202, 203a, b between the sealing surface 102 and the upper face 411. The upwardly facing abutment surface 101 can be in a plane perpendicular to the axis of a can 400 as depicted in fig. 6 or in a slanted plane to the axis of a can 400, i.e. in a plane at an angle different from 90° to the axis of a can 400, as depicted in fig. 7. The upwardly facing abutment surface 101 also can have a curved shape as depicted in fig. 8. The downwardly curved flange edge 412 can have a straight edge as depicted in fig. 6-7 or a slanted edge as depicted in fig. 8.

[0049] According to the invention, an adhesive 201, 203a is applied to the sealing surface 102 as can be seen from fig. 6 and 8. In fig. 8 the adhesive 203b further reaches down to the space between the downwardly curved flange edge 412 and the upwardly facing abutment surface 101. Alternatively or in addition it is preferred to apply adhesive 202 to the downwardly curved flange edge 412 as depicted in fig. 7 so that an adhesive bond is formed between the downwardly curved flange edge 412 and the upwardly facing abutment surface 101.

[0050] Fig. 9 depicts an exemplary embodiment of a mouthpiece 304 closing the opening 600 defined by the unitary plastic part 100. Alternatively to being directly attached to the unitary plastic part 100 the mouthpiece 304 can be part of a cap 300, preferably part of the top part 301 of the cap 300.

Claims

1. A lid attachment (1) for a metal can (400) having an open upper end with a flange (410) forming an annular upper face (411) and exhibiting an outwardly curved flange edge (412) that has an axial distance (A) from the upper face measured in an axial direction of the metal can,

- wherein the lid attachment comprises a unitary plastic part (100) and an adhesive (201, 202, 203a, b),

- wherein the unitary plastic part comprises a hook-shaped annular snap-on ring (105) with an upwardly facing abutment surface (101) and a downwardly facing sealing surface (102),

- wherein an axial distance between the abutment surface and the sealing surface corresponds to the axial distance between the flange edge and the upper face of the metal can,

- wherein the lid attachment is designed for such that the hook-shaped annular snap-on ring upwardly facing abutment surface initially expands when the lid attachment is attached to a can and the upwardly facing abutment surface of the annular snap-on ring springs back behind the flange edge when fully attached to a can, and

- wherein the adhesive is applied to the sealing surface.

2. The lid attachment (1) of claim 1, wherein an inner diameter of the snap-on ring (105) is smaller than a diameter of a flange edge (412) of a metal can (400) the lid attachment is adapted for.

3. The lid attachment (1) of claim 1, wherein the axial distance between the abutment surface and the sealing surface is slightly larger than the axial distance between the flange edge and the upper face of a metal can the lid attachment is designed for.

4. The lid attachment (1) of any one of the preceding claims, wherein the adhesive (201, 202, 203a, b) includes an activation mechanism that activates an adhesive effect and/or an increase in volume of the adhesive in the presence of an activation trigger, wherein the activation trigger is pressure and/or air and/or moisture and/or heat and and/or a contact of at least two adhesive components and/or an absence of air.

5. The lid attachment (1) of any one of the preceding claims, wherein the adhesive (201, 202, 203a, b) includes an expansive material and/or a material sensitive to pressure and/or air and/or moisture and/or heat and and/or a contact of another adhesive components and/or an absence of air.

6. The lid attachment (1) of any one of the preceding claims, wherein the lid attachment, particularly the adhesive (201, 202, 203a, b), is designed for a permanent fixation of the lid attachment, particularly the unitary plastic part (100), to a can (400).

7. The lid attachment (1) of any one of the preceding claims, wherein the lid attachment and the flange are designed for such that the outwardly curved flange edge initially is compressed when the lid attachment is attached to a can and springs back behind the upwardly facing abutment surface of the annular snap-on ring when it is fully attached to a can.

8. The lid attachment (1) of any one of the preceding claims, wherein the lid attachment further comprises a cap (300) designed for closing an opening (600) defined by the unitary plastic part.

9. The lid attachment (1) of the preceding claim, wherein the unitary plastic part (100) comprises a downwardly facing second abutment surface (103) designed for engaging with the cap (300).

10. Metal can (400) having an open upper end with a flange (410) forming an annular upper face (411) and exhibiting an outwardly curved flange edge (412) that has an axial distance (A) from the upper face measured in an axial direction of the metal can, characterized in that the metal can comprises a lid attachment (1) of any one of the preceding claims.

11. Method of attaching a lid to a metal can (400) comprising the steps

- providing a metal can having an open upper end with a flange (410) forming an annular upper face (411) and exhibiting an outwardly curved flange edge (412) that has an axial distance (A) from the upper face measured in an axial direction of the metal can,

- providing a lid attachment (1) comprising a unitary plastic part (100) with a hook-shaped annular snap-on ring (105) with an upwardly facing abutment surface (101) and a downwardly facing sealing surface (102) wherein an axial distance between the abutment surface and the sealing surface corresponds to the axial distance between the flange edge and the upper face of the metal can,

- applying an adhesive (201, 202, 203a, b) to the sealing surface,

- attaching the lid attachment to the metal can wherein the hook-shaped annular snap-on ring upwardly facing abutment surface initially expands and the upwardly facing abutment surface of the annular snap-on ring springs back behind the flange edge when fully attached to a can.

12. The method of the preceding claim, wherein attaching the lid attachment (1) to the metal can comprises that the outwardly curved flange edge (412) initially is compressed when the lid attachment is attached to a can and springs back behind the upwardly facing abutment surface (101) of the annular snap-on ring (105) when it is fully attached to a can (400).

13. The method of any one of the two preceding claims, comprising the step

- activating an adhesive effect and/or an increase in volume of the adhesive (201, 202, 203a, b) in the presence of an activation trigger, wherein the activation trigger is pressure and/or air and/or moisture and/or heat and and/or a contact of at least two adhesive components and/or an absence of air.

14. The method of any of the preceding claims 11-13, further comprising the step

- Providing a permanent fixation of the lid attachment (1), particularly the unitary plastic part (100), preferably via the adhesive (201, 202, 203a, b), to a can.

15. The method of any of the preceding claims 11-14, further comprising the step

- attaching a cap (300) to the unitary plastic part (100) such that the cap closes an opening (600) defined by the unitary plastic part, wherein preferably the cap engages with a downwardly facing second abutment surface (103) of the unitary plastic part.

Drawing