EP2349908A1

EP2349908A1 - Stretchable plastic polymer protective cap for cans or similar containers, having a radial fringe for removal of the cap and device for making said cap

Info

Publication number: EP2349908A1
Application number: EP09756455A
Authority: EP
Inventors: Leon Antoine Ribi
Original assignee: Ribipack SpA
Current assignee: Ribipack SpA
Priority date: 2008-11-11
Filing date: 2009-11-06
Publication date: 2011-08-03
Also published as: CH699874A2; CH699874B1; WO2010055000A1

Abstract

A stretchable plastic polymer protective cap (8) designed to be axially stretchably fitted over the opening of metal containers, such as beverage cans or similar containers (1), having an artifactual ring-shaped radial fringe (3) for manual removal of the cap before opening the can, and device for making such cap.

Description

RIBI PACK S . P . A .

STRETCHABLE PLASTIC POLYMER PROTECTIVE CAP FOR CANS OR SIMILAR CONTAINERS, HAVING A RADIAL FRINGE FOR REMOVAL OF THE CAP AND DEVICE FOR MAKING SAID CAP

PREAMBLE

The present invention relates to a special stretchable plastic polymer cap 8 designed to be axially stretchably fitted along the longitudinal axis of metal containers such as machine-sealed beverage cabs 1 and a device for making such cap 8. This cap 8 is essentially used for hygienically sealing the top, i.e. the part with the pull tab 5, by a tight membrane. Before opening the can, the protective cap 8 should be easily removed to open the can 1. For this purpose, the cap 8 has a kind of radial peripheral ring-shaped fringe 3 formed in the free edge of the membrane 3 that is used to form the cap 8 as it being fitted. Such fringe 3 is generally 5 to 10 mm wide, which allows grasping thereof by two fingers for removal of the cap 8, of which it is part, from the can 1. This fringe 3 is formed by a device, better described hereinafter, composed of a hollow cylinder 7 coaxially sliding between the flat jaws of a gripper 6 that clamps the membrane 2 to be fitted. Therefore, the fringe 3 looks like a corrugated edge, clearly visible on a radial plane, whose deformability does not prevent tight packaging of the cans 1. In prior art, cans 1 are not generally protected by such films. They are usually covered with semi-rigid plastic or deformable aluminum caps, not with tightly fitting membranes 2 and namely not with membranes having a removal device such as the annular fringe 3 of the present invention.

All the other methods that involve the use of a stretchable plastic membrane 2 or film require the latter to be removed before use by scratching the film by a nail to remove the film that adheres to the side wall of the cans 1. This operation is often inconvenient for the consumer and may also affect hygienic opening of the can 1. The membrane 2 having the fringe 3 of the present invention solves the problem in an inexpensive and hygienic manner, fulfils reasonable consumer expectations and is compliant with the laws in force.

TEXT OF THE DESCRIPTION

The cap 8 of the present invention is in the form of an enclosure adhering to the can 1 to about 20% its length, without limitation, from the top of the cylindrical side wall . The top closure and the pull tab 5 of the can 1 are also covered and the membrane 2 is stretched over the circular rim of the closure 4.

The lower edge of the membrane 2 adhering to the cylindrical area of the can 1 is outwardly bent at 90°, creating a widened portion or fringe 3, whose plane is approximately perpendicular to the cylindrical wall of the can. . The fringe 3 has the shape of a thin flat ring surrounding the circumference on the cylindrical wall of the can 1. This fringe 3 maintains its position and shape because, as the membrane 2 is axially and orthogonally stretched beyond its elastic limit, the lack of shrinkage after stretching causes a permanent plastic deformation. Such shrinkage, which allows the membrane 2 to adhere to the cylindrical wall, is essentially caused by necking, i.e. a circular tension around the can, due to the orientation distribution of the long fiber molecules of the polymer along the generatrices of the wall of the can 1, which fibers statistically assume a vertical orientation and parallel to the cylindrical wall of the cans 1 during axial stretching caused by a gripper 6 having annular flat jaws. Furthermore, a hollow cylinder 7 moving concentrically with the annular jaw gripper 6, presses the partially pre-stretched stretchable plastic polymer membrane 2 by its bottom circular rim, thereby causing an irreversible orthogonal plastic deformation on the bent lower edge of the membrane 2 , and forming the fringe 3.

Once plastic deformation of the fringe 3 is completed, the axial force exerted on the membrane 2 by the annular jaw gripper 6 in combination with the hollow cylinder tears the membrane 2 at the end of stroke when the gripper 6 is lifted up without the auxiliary cylinder 7 , thereby leaving the fringe 3 exposed, as a deformed plastic residue.

Utility and use

The pull tab system 5 of the can 1 is accessed by simply grasping said fringe 3 in any position by two fingers and pulling it upwards. Then, the whole membrane 2 that forms the cap 8 will be easily pulled off and leave the top closure 4 of the can 1 exposed, for access to the pull tab 5 of the opening.

In addition to allowing removal of the cap 8 this fringe 3 is an evidence that hygienic protection of the can 1 has not been tampered and that the consumer can safely drink with his/her lips in contact with the opening of the can 1.

A further advantage of the fringe for protecting the opening of the can 1 is that visually impaired or blind consumers may be also assured of the asepsis and hygiene of the opening of the can 1 by touching it.

An additional advantage is that membranes 2 of different colors may be used, whereby local darkening at the fringe 3, caused by a different refractive index of the irreversibly stretched polymer beyond its elastic deformation limit, will reveal the presence of an intact fringe 3.

In addition to the above, the provision of a colored membrane 2 may obviously be advantageously used, for instance, to characterize a type of beverage or indicate the presence of alcohol in the beverage or carry a colored advertisement or an expiration date.

Furthermore, an important advantage in terms of product marketing is that hidden information concerning any prizes or bonuses for additional drinks can be disposed under the membrane 2 , which is only removable by the fringe 3, which will act as a tamper-evident device . In terms of costs, the fringe 3 that characterizes the present invention involves a negligible cost as compared with the whole package, because it has a weight of a few milligrams .

Furthermore , according to applicable laws , various stretchable polymer formulations may be used, whose chemical and mechanical properties may be the most suitable for and compatible with their use in the relevant country. The fringe 3 of the invention will always be an evidence of easy use of the can 1 and a guarantee of product hygiene for consumers .

The cap 8 with the fringe has the essential task of hygienically protecting the opening near the pull tab device 5. There have been reported cases of microbial contamination, that caused local or internal infections , due to the storage of cans 1 in places infested by rats or other disease-carrying animals, causing even serious diseases . The presence of the fringe 3 of the present invention is a guarantee for consumers that the pull tab 5 of the can 1 and its surroundings are sterile and are and will be protected until use.

DEVICE FOR NLAKING THE CAP

The device for forming the cap 8 directly on the cans 1 is essentially composed of a gripper 4 with annular jaws and an auxiliary concentric hollow cylinder 7. These two elements 4 and 7 are preferably mounted to guided vertical rods that may cause said two elements to move up and down by controlled movements , while the cans 1 lie with their bottom on a surface or movable carpet and are conveyed thereby for operation under the jaw gripper 4 and its auxiliary hollow cylinder 7 to a position in which the axes of symmetry of the jaw gripper 4, the auxiliary hollow cylinder 7 and the can 1 are coincident. Such operating systems are known and typically used, for instance, for bottling or fitting stoppers or membranes 2 as seals to the openings of traditional containers with circular openings . The operating procedure is as follows :

1^st. The gripper 4 with annular jaws grips and clamps an aligned guided membrane web 2 from a roll . 2^nd Step I : The gripper 4 and its mating hollow cylinder 7 move down (see Fig. 4) until they lay the membrane 2 on the edge of the closure 4 of the can 1.

3^rd Step II: The gripper 4 moves further down (see Fig. 5) , and stretches the membrane 2 on the edge of the closure 4 , while the hollow cylinder 7 remains in its previous position.

Such initial stretching operation causes a deformation of the membrane 2 that assumes a conical surface with an axial section consisting of two curved generatrices that correspond to two inverted paraboloids of revolution. This shape is caused by necking, resulting from a parallel axial statistical orientation of the molecular fibers of the polymer of the membrane 2 which cause the fibers to move towards one other in the direction of their transverse dimensions . This reduces the circumference of radial sections, whereas the corresponding elastoplastic deformation creates tangential forces perpendicular to the axis of symmetry, that combine with the axial forces to create the equilibrium surface . The invention particularly utilizes this effect for the operation of the device .

4^th Step III: The auxiliary hollow cylinder 7 (see

Fig. 6) sealably moves down into the hole created by the jaws of the gripper 4 and further deforms the membrane 2 by pressing it until a step is created at the interface o the jaws of the gripper 4.

The gap between the inner diameter of the hollow cylinder 7 and the outer diameter of the cylindrical wall of the can 1 may be of 4 to even 10 times the thickness of the stretched membrane 2. Therefore, such stretching causes the step-like deformation to be permanent, thereby forming the desired fringe 3. The above values may obviously change according to the mixtures of polymers that compose the membrane 2 , the temperatures and stretching rates.

5^th Step IV: As the gripper 4 clamps the membrane between the jaws, it moves up (see Fig. 7) to its top position to allow ejection of the capped can 1, thereby tearing the membrane 2 against the outer sharp edge of the bottom rim of the auxiliary hollow cylinder 7.

6^th Step V: The hollow cylinder 7 also moves to its top position whereas the annular jaws of the gripper 4 open to feed the web of the membrane 2 and restart the cycle .

Minor variants of the above described cycle may be obviously used for special optimizations .

KEY OF DRAWINGS

1) Can

2) Membrane 3) Fringe

4) Top rim of can

5) Pull tab device

6) Annular jaw gripper

7) Auxiliary hollow cylinder 8) Cap (membrane stretched on can closure, with fringe)

Fig. 1 - The figure is an axial cross sectional view of a can 1 with a cap 8 thereon.

Fig. 2 - The figure is a top view of a can 1 with a cap 8 having a fringe 3.

Fig. 3 - The figure is a side view of a capped can. The annular fringe 3 is shown.

Fig. 4 - The figure is a cross sectional view of a can 1 that is about to be capped by the device 8.

Fig. 5 - The figure shows the gripper 4 of the device 8 that has already stretched the membrane 2. Fig. 6 - The figure shows the hollow cylinder of the device 8, that has already orthogonally deformed the membrane 2 to obtain the fringe 3.

Fig. 7 - The figure shows the gripper 4 that has moved up to its highest level after tearing the membrane 2 against the outer bottom sharp edge of the auxiliary hollow cylinder 7.

Fig. 8 - The figure shows the auxiliary hollow cylinder 7 back into its highest position, the gripper

4 with the jaws open and the capped can 1 with its annular fringe. Now the device 8 is ready to restart the cycle.

Claims

1) A cap (8) fitted on the sealed opening (4) of beverage cans (1) or equivalent containers and composed of a stretchable plastic polymer membrane (2) , adhering to their top closure (4) and their cylindrical side wall, characterized in that it has a ring-shaped fringe (3) or annular widened portion that forms the extension of the lower edge of the membrane (2) being fitted.

2) A cap (8) as claimed in claim 1) , characterized in that it is obtained by stretching a stretchable plastic polymer membrane (2) along the longitudinal axis of the cans (1) against the top closure (4) of the closed can (1) to adhesion to said top closure (4) and the side wall and by permanent orthogonal deformation of the free lower end edge of the membrane (2) to form the fringe (3) .

3) A cap (8) as claimed in claims 1) and 2) , characterized in that the membrane (2) is stretched and adhered by using an annular gripper (6) having two concentric jaws that clamp a stretchable plastic polymer film and push it vertically against the top closure (4) of the cans (1) to fit it thereon.

4) A cap (8) as claimed in claim 2) et seq. , characterized in that the fringe (3) is formed using an auxiliary hollow cylinder (7) coaxial with the jaws of the annular gripper (6) and the can (1) and disposed between the annular gripper (6) and the can (1) , which also acts and vertically presses upon the membrane (2) to cause the desired permanent orthogonal plastic deformation thereof .

5) A cap (8) as claimed in claim 2) et seq. , characterized in that the fringe (3) resulting from permanent deformation of the free edge of the membrane (2) caused by the hollow cylinder 7, assumes the shape of a ring lying on a plane approximately perpendicular to the longitudinal or symmetry axis of the cans (1) .

6) A cap (8) as claimed in claims 1) et seq. , characterized in that its fringe is conceived and formed to allow removal of the cap by the fingers , to access the pull tab device (5) of the cans (1) .

7) A cap (8) as claimed in claims 1 et seq. , characterized in that it can hide an advertisement or an encrypted and/or confidential message to the consumer between the stretchable plastic polymer membrane (2) and the can (1) , with the non-tampered fringe (3) ensuring integrity and secrecy thereof.

8) A device for making the cap (8) characterized in that it comprises a gripper 4 having two annular jaws consisting of two mating flat rings having a slightly larger inner diameter than, i.e. ensuring a seal with, the outer diameter of an auxiliary hollow cylinder (7) , whose inner diameter is in turn larger than the outer diameter of the cylindrical wall of the containers to be capped.

9) A device as claimed in claim 8) , wherein both the annular jaws of the gripper (4) and the auxiliary hollow cylinder (7) can move in a vertical and mutually independent manner along their axes of symmetry using any suitable device that guides and controls their vertical coaxial movements , but preferably vertical rods, sliding along guides that are in turn fixedly anchored to a bed through a raised frame, the cans (1) to be capped being designed to move on said bed, through belt conveyors or equivalent devices .

10) A device as claimed in claim 8) et seq. , characterized in that the two jaws of the gripper (4) have mutually facing surfaces processed to have such a friction coefficient as to prevent the membrane 2 clamped thereby from slipping.

11) A device as claimed in claim 8) et seq. , characterized in that the outer bottom rim of the auxiliary hollow cylinder 7 has a sharp edge to facilitate tearing of the membrane 2 when the gripper 4 moves up after stretching the membrane 2 on the can 1.

12) A device as claimed in claim 8) et seq. , characterized in that the bottom inner rim of the auxiliary hollow cylinder 7 has a rounded edge to facilitate stretching and orthogonal deformation of the membrane 2 and obtain the fringe 3.