SEALING FOIL WITH TEAR LINE

Description

[0001] The present invention relates to sealing foils for use in packaging and in particular to sealing foils having a weakened tear line along which the foil may be torn to open the package. The invention also relates to a method of forming such a sealing foil.

[0002] Packages are available in many forms and sizes according to the product to be contained. In the food packaging industries, the presence of a sealing foil can be of great importance in maintaining a product in sterile or fresh condition prior to use. One form of seal that has been disclosed for such packaging is shown in WO2014062119. The seal comprises two layers welded together, wherein the first layer is an aluminium laminate that can be heat sealed or otherwise welded to the sides of a container e.g. using an induction welding process.

[0003] In order to open such seals, they may be provided with a tear line extending along a tearing path around the lid. The tear line may cut the first layer but may not penetrate a hermetic second layer located beneath the first layer and welded thereto. A pull tab may be provided for a user to grasp and commence tearing the first layer along the tearing path. In order to achieve adequate opening it is important that the tear line is without interruption or that any such interruptions are minimal as these may lead to uncontrolled ripping of the sealing foil in a direction other than along the tearing path.

[0004] A seal is disclosed in WO2005075314 that has a pull tab, which leads into a tear line that is continuous through a lead-in section and a circumferential section. Although in theory this arrangement ensures a continuous tear, in practice, the manner in which the tear line is produced may lead to undesired discontinuities. Forming of the tear line generally takes place by punching or die-cutting with a series of punches, each having a blade for cutting a portion of the tear line. For production purposes, the circumferential section is cut using a punch that is different from that of the lead-in section. Alignment of one punch with the following punch determines the accuracy with which the different portions of the tear line align to each other. Furthermore, in order that sealing prior to opening is not compromised, the tear line should be confined within the region covered by the hermetic second layer. Since these layers are not always co-extensive, and are assembled together by welding after cutting of the tear line, careful positioning is required. Another such closing foil is known from US 3,776,450. JP S61 217350 discloses a sealing foil according to the preamble of claim 1. Due to manufacturing tolerances, existing arrangements have led to at least some sealing foils having discontinuous tear lines that can lead to uncontrolled ripping on opening of the seal.

[0005] It would be desirable to provide an alternative arrangement that allows accurate placement of the tear line and encourages correct opening of the seal without ripping. According to the invention there is provided a sealing foil for closing a packaging container comprising the features according to claim 1. The foil comprises: a pre-cut first layer; a hermetic second layer, connected to the first layer and coextensive therewith over the full extent of the second layer; wherein the first layer is pre-cut with a plurality of tear lines defining a tearing path leading from a pull tab to a tear end such that a central portion of the sealing foil can be removed to provide an access opening to the container and a lead-in tear line is contiguous with a circumferential tear line such that uncontrolled ripping of the sealing foil is prevented. In the present context, contiguous to one another, is intended to require that the portions of the tear line run parallel and adjacent to such an extent that a tear is obliged to follow from one portion of the tear line to a following portion, whereby uncontrolled ripping away from the tear path is avoided.

[0006] In one embodiment, the sealing foil is not square shaped. In particular, the sealing foil may be of a rectangular shape with the longer sides of the foil preferably being outwardly bowed. The shorter sides are preferably without a radius between the corners of the foil. Furthermore, the sealing foil has corners that are rounded off. The bowed sides and rounded corners facilitate controlled tearing of the foil. Furthermore, the lead-in tear line should join the circumferential tear line on one of the longer sides, preferably as far from the corner as possible. In one embodiment, the lead-in tear line should join the circumferential tear line at a about the mid-point of the longer side or earlier.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The features and advantages of the invention will be appreciated upon reference to the following drawings of a number of exemplary embodiments, in which:

Figure 1 shows a prior art sealing foil;

Figure 2 shows a detail of the prior art sealing foil of Figure 1;

Figure 3 shows the detail of Figure 2, during opening of the sealing foil;

Figure 4 shows a detail of part of a sealing foil according to an embodiment not falling under the scope of the invention ;

Figure 5 shows a detail of part of a sealing foil according to an embodiment of the invention; and

Figure 6 shows a detail of part of a sealing foil not falling under the scope of the invention.

[0008] Figure 1 shows an existing sealing foil 1 as may be used in various types of food packaging such as drinks powders, infant formulas and the like. The foil 1 comprises a first layer 2 and a second layer 3, which are joined together by welding at various points on their surface. The first layer 2 is formed of a heat-sealable aluminium laminate and extends to an outer circumference 4 that can be joined by heat sealing (such as induction sealing) to an inside wall of a container (not shown). The second layer 3 is slightly smaller than the first layer 2 and is formed of a heat sealable aluminium laminate, with the first and second layers 2, 3 being joined together face to face with the heat sealable surfaces engaged. It will be understood that other appropriate materials may be used for these layers e.g. polymer materials.

[0009] A tear path 5 is formed in the upper first layer leading from a pull tab 6 to a tear end 7. The tear path 5 comprises a series of tear lines 5A, 5B, 5C, pre-cut through the material of the first layer 2. These include a first diagonal, lead-in tear line 5A, a second circumferential tear line 5B and an inner tear line 5C. The pull tab 6 and the diagonal tear line 5A are angled to the circumferential tear line 5B by around 20 degrees. On pulling on the pull tab 6, the sealing foil 1 tears along the tear path 5 whereby the pre-cut first layer 2 causes the underlying second layer 3, which is welded to it, to be torn in a controlled manner. A central portion 8 of the sealing foil 1 is thus removed and an opening formed corresponding to the circumferential tear line 5B.

[0010] Figure 2 shows an enlarged portion of Figure 1 illustrating the intersection of the diagonal tear line 5A with the circumferential tear line 5B. As can be seen, these are formed as separate cuts and they are not contiguous with each other at the point of intersection. This is because the tear line 5B is formed in a separate cutting action to that of the diagonal tear line 5A using a different punch or blade. The accuracy by which the production machine can be set up will determine the size of the gap G. In an existing arrangement, the blade that forms the diagonal tear line 5A is set to avoid the possibility of passing the circumferential tear line 5B. This is to avoid any chance that the diagonal line 5A could extend beyond the outer extent of the second layer 3, once the layers 2, 3 are assembled together.

[0011] Figure 3 shows the detail of Figure 2 during opening of such a conventional foil 1. As a user pulls in the direction P on the pull tab 6, the second layer 3 is caused to tear along the diagonal tear line 5A towards the intersection with the circumferential tear line 5B. Due to the presence of the gap G, the tear does not proceed correctly and instead both the first layer 2 and the second layer 3 rip in the direction R. Such uncontrolled ripping of the sealing foil 1 is undesirable.

[0012] Figure 4 shows an embodiment of a sealing foil 10 not covered by the claims of the invention, shown in detail view corresponding to Figure 2. Other parts of the sealing foil 10 may be identical to the prior art foil of Figure 1 and are provided with like references preceded by 10. According to Figure 4, the diagonal tear line 15A has a curved end 15D that crosses the circumferential tear line 15B and turns in a tangential direction to it. In this context tangential is intended to include both collinear and parallel i.e. it is sufficient that the curved end has at least a portion that lies parallel to the circumferential tear line 15B and may even terminate in a direction returning towards the circumferential tear line 15B. In this manner, during operation the tear will progress along the diagonal tear line 15A and will either directly join the circumferential tear line 15B or cross over via the curved end 15D and then return to join it subsequently. Uncontrolled ripping is thus eliminated, even if the diagonal tear line 15A and circumferential tear line 15B are cut by different punches in different steps and careful alignment of the respective punches is no longer essential.

[0013] Figure 5 shows an embodiment of a sealing foil 20 according to the invention in a detailed view similar to Figure 4. Like references in this embodiment are used, preceded by 20. According to this embodiment, the diagonal tear line 25A has an extended curved end 25D that is tangential to the circumferential tear line 25B over an extended length. Again, in this context tangential is intended to include parallel, since these lines 25B, 25D will only coincide if the set-up of the respective punches is accurate. Nevertheless, irrespective of their accuracy, during opening of the sealing foil 20 of Figure 5, the tear progressing along curved end 25D is tearing parallel to the circumferential tear line 25B and will be more likely to continue in this direction since the force as applied in following curved end 25D is in the same direction as the circumferential tear line 25B.

[0014] Figure 6 shows a sealing foil 30 not covered by the claims of the invention in a detailed view similar to Figure 4. Like references are used, preceded by 30. According to this example, the diagonal tear line 35A extends into the circumferential tear line 35B and continues uninterrupted to the tear end 37. These sections of the tear line 35A, 35B can be cut with a single blade or punch in a single process.

[0015] Although reference is given here and throughout the description to the tear line being uninterrupted, the skilled person will be aware that minor interruption of the cut formed through the first layer may be present. These maintain the integrity of the first layer and prevent the tear line from opening during production and/or prior to use in areas where the first layer and the second layer may not be welded or otherwise connected together. Many modifications in addition to those described above may be made to the structures and techniques described herein without departing from the scope of the invention, which is defined in the claims.

[0016] In particular, although the pull tab has been shown at a diagonal to the circumferential tear line, it may do so at any angle between perpendicular and 5 degrees and the lead-in tear line may be straight or curved. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.

Claims

1. A sealing foil (1) for closing a packaging container comprising:

a pre-cut first layer (2);

a second layer (3), connected to the first layer and coextensive therewith over the full extent of the second layer;

wherein the first layer is pre-cut with a plurality of tear lines defining a tearing path (5) leading from a pull tab (6) to a tear end (7) such that a central portion (8) of the sealing foil can be removed to provide an access opening to the container,

characterized in that the second layer is a hermetic layer, and in that a lead-in tear line (5A) is contiguous with a circumferential tear line (5B) and curves tangentially to but does not cross, the circumferential tear line such that uncontrolled ripping of the sealing foil is prevented.

2. The sealing foil according to claim 1, wherein the lead-in tear line extends at an angle of between 90 degrees and 5 degrees to the circumferential tear line preferably at an angle of between 30 degrees and 10 degrees.

3. The sealing foil according to any preceding claim, wherein the lead-in tear line comprises a first straight portion that is diagonal to the circumferential tear line.

4. The sealing foil according to any preceding claim, wherein the first layer extends beyond the second layer for connection to an inner wall of the container.

5. The sealing foil according to any preceding claim, wherein the first layer is a laminate comprising aluminium.

6. The sealing foil according to any preceding claim, wherein the second layer comprises an oxygen barrier material.

7. The sealing foil according to any preceding claim, further comprising an inner tear line (5C) and the pull tab is formed between the inner tear line and the lead-in tear line.

8. The sealing foil according to any preceding claim, wherein a portion of the lead-in tear line runs parallel and adjacent to the circumferential tear line.

9. The sealing foil according to any preceding claim, wherein the circumferential tear line extends completely around the central portion whereby the opening corresponds to the circumferential tear line.

10. A method of manufacture of a sealing foil according to any preceding claim, comprising:

providing a quantity of material for forming the first layer;

pre-cutting the first layer with a series of cuts to define the tearing path;

providing a quantity of material for forming the second layer; and

joining the first and second layers together.

11. The method of claim 10, wherein the first layer is pre-cut using a punch having a first blade portion to form a diagonal cut and a second blade portion to form a circumferential cut and the first and second blade portions are contiguous and join at a sloping T-junction.

12. The method of claim 10, wherein the first layer is pre-cut using a punch having a blade having a diagonal portion and a circumferential portion.

13. The method of any of claims 10 to 12, wherein the first layer is joined to the second layer by induction welding.

Ansprüche

1. Versiegelungsfolie (1) zum Verschließen eines Verpackungsbehälters, die Folgendes umfasst:

eine vorgeschnittene erste Schicht (2);

eine zweite Schicht (3), die mit der ersten Schicht verbunden ist und sich mit dieser über die gesamte Ausdehnung der zweiten Schicht erstreckt;

wobei die erste Schicht mit einer Vielzahl von Aufreißlinien vorgeschnitten ist, die einen Aufreißweg (5) definieren, der von einer Zuglasche (6) zu einem Aufreißende (7) führt, so dass ein Mittelteil (8) der Versiegelungsfolie entfernt werden kann, um eine Zugangsöffnung zu dem Behälter bereitzustellen,

gekennzeichnet dadurch, dass die zweite Schicht eine hermetische Schicht ist und dass eine einleitende Aufreißlinie (5A) an eine umlaufende Aufreißlinie (5B) angrenzt und sich tangential zu der umlaufenden Aufreißlinie zuläuft, diese aber nicht kreuzt, so dass ein unkontrolliertes Einreißen der Versiegelungsfolie verhindert wird.

2. Versiegelungsfolie nach Anspruch 1, wobei sich die einleitende Aufreißlinie in einem Winkel zwischen 90 Grad und 5 Grad zu der umlaufenden Aufreißlinie, vorzugsweise in einem Winkel zwischen 30 Grad und 10 Grad, erstreckt.

3. Versiegelungsfolie nach einem der vorhergehenden Ansprüche, wobei die einleitende Aufreißlinie einen ersten geraden Teil umfasst, der diagonal zu der umlaufenden Aufreißlinie ist.

4. Versiegelungsfolie nach einem der vorhergehenden Ansprüche, wobei sich die erste Schicht zur Verbindung mit einer Innenwand des Behälters über die zweite Schicht hinaus erstreckt.

5. Versiegelungsfolie nach einem der vorhergehenden Ansprüche, wobei die erste Schicht ein Laminat ist, das Aluminium umfasst.

6. Versiegelungsfolie nach einem der vorhergehenden Ansprüche, wobei die zweite Schicht ein Sauerstoffbarrierematerial umfasst.

7. Versiegelungsfolie nach einem der vorhergehenden Ansprüche, die ferner eine innere Aufreißlinie (5C) umfasst und die Zuglasche ist zwischen der inneren Aufreißlinie und der einleitenden Aufreißlinie gebildet.

8. Versiegelungsfolie nach einem der vorhergehenden Ansprüche, wobei ein Teil der einleitenden Aufreißlinie parallel zur und angrenzend an die umlaufende Aufreißlinie verläuft.

9. Versiegelungsfolie nach einem der vorhergehenden Ansprüche, wobei sich die umlaufende Aufreißlinie vollständig um den Mittelteil erstreckt, wodurch die Öffnung der umlaufenden Aufreißlinie entspricht.

10. Verfahren zur Herstellung einer Versiegelungsfolie nach einem der vorhergehenden Ansprüche, das Folgendes umfasst:

Bereitstellen einer Materialmenge zum Bilden der ersten Schicht;

Vorschneiden der ersten Schicht mit einer Reihe von Schnitten, um den Aufreißweg zu definieren;

Bereitstellen einer Materialmenge zum Bilden der zweiten Schicht; und

Zusammenfügen der ersten und zweiten Schicht.

11. Verfahren nach Anspruch 10,
wobei die erste Schicht unter Verwenden eines Stempels mit einem ersten Klingenabschnitt zum Bilden eines diagonalen Schnitts und einem zweiten Klingenabschnitt zum Bilden eines Umfangsschnitts vorgeschnitten wird und der erste und zweite Klingenabschnitt aneinandergrenzen und an einer geneigten T-Verbindung verbunden sind.

12. Verfahren nach Anspruch 10,
wobei die erste Schicht unter Verwenden eines Stempels mit einer Klinge vorgeschnitten wird, die einen diagonalen Abschnitt und einen Umfangsabschnitt aufweist.

13. Verfahren nach einem der Ansprüche 10 bis 12,
wobei die erste Schicht durch Induktionsschweißen mit der zweiten Schicht verbunden ist.

Revendications

1. Feuille d'étanchéité (1) pour fermer un récipient d'emballage comprenant :

une première couche prédécoupée (2) ;

une deuxième couche (3), reliée à la première couche et coextensive avec celle-ci sur toute l'étendue de la deuxième couche ;

où la première couche est prédécoupée avec une pluralité de lignes de déchirure définissant un tracé de déchirure (5) menant d'une languette de traction (6) à une extrémité de déchirure (7) de sorte qu'une partie centrale (8) de la feuille d'étanchéité peut être enlevée pour fournir une ouverture d'accès au conteneur,

caractérisée en ce que la deuxième couche est une couche hermétique, et en ce qu'une ligne de déchirure d'entrée (5A) est contiguë à une ligne de déchirure circonférentielle (5B) et s'incurve tangentiellement mais ne croise pas la ligne de déchirure circonférentielle de sorte qu'une déchirure incontrôlée de la feuille d'étanchéité est empêchée.

2. Feuille d'étanchéité selon la revendication 1, où la ligne de déchirure d'entrée s'étend à un angle compris entre 90 degrés et 5 degrés par rapport à la ligne de déchirure circonférentielle, de préférence à un angle compris entre 30 degrés et 10 degrés.

3. Feuille d'étanchéité selon l'une quelconque des revendications précédentes, où la ligne de déchirure d'entrée comprend une première partie droite qui est diagonale par rapport à la ligne de déchirure circonférentielle.

4. Feuille d'étanchéité selon l'une quelconque des revendications précédentes, où la première couche s'étend au-delà de la deuxième couche pour se connecter à une paroi interne du récipient.

5. Feuille d'étanchéité selon l'une quelconque des revendications précédentes, où la première couche est un stratifié comprenant de l'aluminium.

6. Feuille d'étanchéité selon l'une quelconque des revendications précédentes, où la deuxième couche comprend un matériau barrière à l'oxygène.

7. Feuille d'étanchéité selon l'une quelconque des revendications précédentes, comprenant en outre une ligne de déchirure intérieure (5C) et la languette de traction est formée entre la ligne de déchirure intérieure et la ligne de déchirure d'entrée.

8. Feuille d'étanchéité selon l'une quelconque des revendications précédentes, où une partie de la ligne de déchirure d'entrée s'étend parallèlement et adjacente à la ligne de déchirure circonférentielle.

9. Feuille d'étanchéité selon l'une quelconque des revendications précédentes, où la ligne de déchirure circonférentielle s'étend complètement autour de la partie centrale, l'ouverture correspondant à la ligne de déchirure circonférentielle.

10. Procédé de fabrication d'une feuille d'étanchéité selon l'une quelconque des revendications précédentes, comprenant :

fournir une quantité de matériau pour former la première couche ;

prédécouper la première couche avec une série de coupes pour définir le tracé de déchirement ;

fournir une quantité de matériau pour former la deuxième couche ; et

joindre les première et deuxième couches ensemble.

11. Procédé selon la revendication 10,
où la première couche est prédécoupée à l'aide d'un poinçon ayant une première partie de lame pour former une coupe diagonale et une deuxième partie de lame pour former une coupe circonférentielle et les première et deuxième parties de lame sont contiguës et se rejoignent au niveau d'une jonction en T inclinée.

12. Procédé selon la revendication 10, où la première couche est prédécoupée à l'aide d'un poinçon comportant une lame présentant une partie diagonale et une partie circonférentielle.

13. Procédé selon l'une quelconque des revendications 10 à 12,
où la première couche est jointe à la deuxième couche par soudage par induction.

Drawing