TAMPER EVIDENT CLOSURE

Description

[0001] The invention is related to a tamper evident closure according to the preamble of claim 1 EP 0 179 199 A discloses such a closure.

[0002] Such closures are for instance applied for containers with nutritional or pharmaceutical products. A typical process of manufacturing babyfood in glass jars comprises filling the jars with the contents at increased temperature and placing a cap on the jar by means of a "steamcapper" as is known in the art. Subsequently the jars are placed in a retort for sterilisation, as to guarantee an excellent microbiological quality for the product.

[0003] During and directly after the heat treatment process large changes in physical conditions (pressure, temperature) occur, which puts high demands on the closure with regard to tightness. The closure forms a tight seal which resists the normal forces that could occur during transport and distribution and shelf life.

[0004] In addition, it is of utmost importance to the consumer that the package has not been opened before. This would guarantee the consumer that no micro-organisms, chemicals, toxins etc. have been introduced in the product.

[0005] For this reason, closures have been developed which demonstrate a clear audible signal once the product is being opened. Reference is made to the well-known tin caps for closures of glass jars. On the inside, these caps are covered by a soft material (compound) that can withstand the conditions and allows a consistent closure of the jar. By pressing and twisting the cap can be removed. Once the vacuum, that was created during the cooling process, disappears the cap takes it original form and a "clicking sound" can be heard. Despite the good closure and tamper-evident properties the caps are expensive to produce and are difficult to modify (shape or printing) to give it a unique appearance. The latter disadvantage is more serious when many different products are sold in the same type of package. In addition high demands are put on the quality and nature of the inner compound of the cap, in order to ensure easy twisting of the cap and to prevent contamination of the contents of the jar.

[0006] Furthermore, homogeneous plastic caps have been developed which can resist retorting conditions. However, some appeared not to be able to produce an audible signal. Thus, additional tamper-evident members such as a paper or plastic sealing were required. These are however less practical to the consumer.

[0007] Also caps were developed which consisted of two parts: one plastic part which was used for closing the jar and which has a circular opening above the opening of the jar, and a second part that consists of a circular shaped tin plate which fits in this opening and which produces the audible signal when the cap is twisted off. These caps are even more expensive to produce and have more limitations with regard to the possibilities to introduce modifications in the shape of the cap with regard to printing.

[0008] The object of the invention is to provide a closure which does not have these disadvantages, instead the closure should be relatively cheap and should be able to produce an improved audible sound upon opening. This object is achieved by means of the features of the characterising part of claim 1.

[0009] It appears that a cap of a polymer material having a spherically convex stable shape is able to produce an audible signal, upon changing the instable shape into the stable shape. The polymer material in question should be of a certain stiffness for producing such sound, and therefore preference is given to a propylene material. Furthermore, good results are obtained in case at least a part of the cap is of a composite polymer material, e.g. containing fibres.

[0010] Also, the polymer material (compound) can resist the conditions that result from the heating or cooling process. It forms consistently an air tight closure, experiences less problems with lubrication, contamination or discoloration (browning of compound), allows large flexibility with regard to shape or colour of the cap and possibility for printing.

[0011] The loudness of the audible signal is improved by selecting an appropriate design of the cap. Between the central cap part and the rim a ring shaped cap part is provided, the central cap part in its stable shape and said ring shaped cap part intersecting each other according to a non-zero intersecting angle in a radial cross-section of the closure.

[0012] In order to ascertain a proper, tight sealing of the closure, it is preferred that the point of intersection between the central cap part and the ring shaped part, in a radial cross-section of the closure, has a distance to the outside of the rim which is at least equal to the thickness of said rim. In case the inner surface of the rim is coated, the point of intersection has a distance to the outside of the rim which is at least equal to the sum of the thickness of said rim and the thickness of said coating. Good results can be obtained in case the point of intersection has a distance to the outside of the rim which is at least equal to the sum of the thickness of said rim and the thickness of the neck or throat of the jar.

[0013] The transfer between the instable and stable position of the cap is promoted by introducing a switch area which has a smaller thickness than the remainder of the cap, said switch area enabling the transfer between the instable and stable positions of the cap. This switch area has a thickness which is 0,1 - 0,9 times the thickness of the remainder of the cap; preferably the switch area has a thickness which is 0,2 - 0,8 times the thickness of the remainder of the cap.

[0014] Said switch area may be situated at the position of the point of intersection. It can take the form of a continuous ring, but is may also be constituted by a series of spots.

[0015] The intersecting angle α between the central cap part and the ring is comprised in the range of 4° - 15°.

[0016] The invention will now be described further with reference to an embodiment of the closure shown in the figures.

Fig. 1 shows a jar comprising a closure according to the invention.

Fig. 2 shows an axial cross section through the jar and closure according to fig. 1.

Fig. 3 shows a view in perspective.

Fig. 4 shows a view in perspective of the inside of the cap of the closure according to the invention.

Fig. 5 shows an enlarged detail of the further embodiment of the closure, in axial cross section.

[0017] As shown in the figures 1 - 5, ajar 2, e.g. of glass, is provided with a cap 1 according to the invention. This cap 1 has a rim 5 which comprises a screw thread 10 on the inside. The neck 4 of the jar comprises a corresponding screw thread 11 on the outside. By screwing the cap 1 on the jar 2, a tight seal can be obtained between the upper surface 12 of the neck 4, and the lower surface 13 of the ring shaped cap part 8. This lower side 13 is defined by a coating 9, which stretches over the rim 5 and the ring shaped cap part 8.

[0018] The central cap part 7 is spherically convex, and has a stable dome shaped indicated by with full lines in fig. 5, as well as an instable, almost flat shape indicated with dotted lines in said fig. 5.

[0019] The central cap part 6 joins the ring shaped cap part 8 through a line of intersection 14, which in the embodiment shown is a continuous line. Alternatively, the intersection will also be discontinuous.

[0020] At the spot of the line of intersection 14, a switch area is defined, which switch area has a reduced thickness with respect to the remainder of the cap (not shown). The switch area has the thickness of 0,1 - 0,9 times the thickness of the remainder of the cap, or preferably 0,2 - 0,8 times.

[0021] At said line of intersection 14, an angle α is defined, in the axial cross section shown in fig. 2, between the ring shaped cap part 8 and the central cap part 7, which angle can range from 4° - 15°.

[0022] The distance w between the line of intersection 14 and the outer circumference of the ring, is preferably at least equal to the sum of the thickness of said ring, the thickness of the coating 9, and the thickness of the neck 4.

Claims

1. Tamper evident closure for a container (2) such as a jar, comprising a cap (1) of a polymer material and means (3) for connecting the cap (1) to a neck (4) or throat of said container (2), said cap (1) comprising a rim (5) and an end wall (6) which can be brought into two end shapes, one of said end shapes being mechanically stable and the other end shape being mechanically instable, wherein the end wall (6) can be held in its instable position under the influence of a pressure difference over the inside and the outside when being connected to the container (2), and can be released towards its stable position by removing said pressure difference when being released from the container (2), said transfer from the instable to the stable position being accompanied by an audible sound, wherein the cap (1) comprises a central cap part (7), a ring shaped cap part (8) being provided between the central cap part (7) and the rim (5), the central cap part in its stable shape and said ring shaped cap part (8) intersecting each other according to a non-zero intersecting angle in a radial cross-section of the closure, characterised in that the stable shape of the central cap part (7) is defined by an outer surface which is spherically convex, in that the intersecting angle α is comprised in the range of 4° - 15°, in that the cap (1) has at least one switch area which has a thickness which is 0,1 - 0,9 times the thickness of the remainder of the cap, said at least one switch area enabling the transfer between the instable and stable positions of the cap (1), and in that the cap (1) is of a composite propylene polymer material.

2. Closure according to claim 1, wherein the point of intersection between the central cap part (7) and the ring shaped part (8), in a radial cross-section of the closure, has a distance to the outside of the rim (5) which is at least equal to the thickness of said rim (5).

3. Closure according to claim 2, wherein the inner surface of the rim (5) is coated, the point of intersection having a distance to the outside of the rim (5) which is at least equal to the sum of the thickness of said rim (5) and the thickness of said coating (9).

4. Closure according to claim 2 or 3, wherein the point of intersection has a distance to the outside of the rim (5) which is at least equal to the sum of the thickness of said rim (5) and the thickness of said neck (4) or throat.

5. Closure according to any of the preceding claims, wherein the switch area has a thickness which is 0,2 - 0,8 times the thickness of the remainder of the cap.

6. Closure according to any of the preceding claims, wherein the switch area is at the position of the point of intersection.

7. Closure according to any of the preceding claims, wherein the switch area is a continuous ring.

8. Closure according to any of the preceding claims, wherein the switch area is constituted by a series of spots.

9. Closure according to any of the preceding claims, wherein at least one part of the cap (1) is of a composite polymer material containing fibres.

10. Closure according to claim 3, wherein the coating is of a polyethylene polymer.

11. Closure according to any of the preceding claims, wherein the cap is of a homogeneous character.

12. Closure according to any of the preceding claims, wherein the cap is of a mainly circular symmetric shape.

13. In combination, a closure according to any of the preceding claims, as well as a container.

14. Cap (1) for a closure according to any of the preceding claims.

Ansprüche

1. Unversehrtheitssicherungsverschluss für einen Behälter (2) wie z.B. ein Gefäß, umfassend einen Verschlussdeckel (1) aus einem Polymermaterial und Mittel (3) zum Verbinden des Verschlussdeckels (1) mit einem Hals (4) oder einer Kehle des genannten Behälters (2), wobei der genannte Verschlussdeckel (1) einen Rand (5) und eine Endwand (6) umfasst, die in zwei Endformen gebracht werden kann, wobei eine der genannten Endformen mechanisch stabil und die andere Endform mechanisch instabil ist, wobei die Endwand (6) unter dem Einfluss eines Druckdifferentials über der Innenseite und der Außenseite in ihrer instabilen Position gehalten werden kann, wenn sie mit dem Behälter (2) verbunden ist, und durch Wegnehmen des genannten Druckdifferentials in Richtung auf ihre stabile Position gelöst werden kann, wenn sie von dem Behälter (2) gelöst wird, wobei der genannte Transfer von der instabilen in die stabile Position von einem hörbaren Ton begleitet wird, wobei der Verschlussdeckel (1) einen mittleren Verschlussdeckelteil (7) umfasst, wobei ein ringförmiger Verschlussdeckelteil (8) zwischen dem mittleren Verschlussdeckelteil (7) und dem Rand (5) vorgesehen ist, wobei der mittlere Verschlussdeckelteil in seiner stabilen Form und der genannte ringförmige Verschlussdeckelteil (8) einander in einem Schnittwinkel von ungleich null in einem radialen Querschnitt des Verschlusses schneiden, dadurch gekennzeichnet, dass die stabile Form des mittleren Verschlussdeckelteils (7) durch eine Außenfläche definiert wird, die sphärisch konvex ist, dadurch, dass der Schnittwinkel α im Bereich von 4° bis 15° liegt, dadurch, dass der Verschlussdeckel (1) wenigstens einen Schaltbereich hat, der eine Dicke hat, die das 0,1 - 0,9fache der Dicke des Rests des Verschlussdeckels beträgt, wobei der genannte Schaltbereich den Transfer zwischen der instabilen und der stabilen Position des Verschlussdeckels (1) ermöglicht, und dadurch, dass der Verschlussdeckel (1) aus einem Composite-Propylenpolymermaterial besteht.

2. Verschluss nach Anspruch 1, wobei der Schnittpunkt zwischen dem mittleren Verschlussdeckelteil (7) und dem ringförmigen Teil (8) in einem radialen Querschnitt des Verschlusses einen Abstand zur Außenseite des Randes (5) hat, der wenigstens gleich der Dicke des genannten Randes (5) ist.

3. Verschluss nach Anspruch 2, wobei die Innenfläche des Randes (5) beschichtet ist, wobei der Schnittpunkt einen Abstand zur Außenseite des Randes (5) hat, der wenigstens gleich der Summe der Dicke des genannten Randes (5) und der Dicke der genannten Beschichtung (9) ist.

4. Verschluss nach Anspruch 2 oder 3, wobei der Schnittpunkt einen Abstand zur Außenseite des Randes (5) hat, der wenigstens gleich der Summe der Dicke des genannten Randes (5) und der Dicke des genannten Halses (4) oder der genannten Kehl ist.

5. Verschluss nach einem der vorherigen Ansprüche, wobei der Schaltbereich eine Dicke hat, die das 0,2 - 0,8fache der Dicke des Rests des Verschlussdeckels beträgt.

6. Verschluss nach einem der vorherigen Ansprüche, wobei der Schaltbereich an der Position des Schnittpunkts liegt.

7. Verschluss nach einem der vorherigen Ansprüche, wobei der Schaltbereich ein kontinuierlicher Ring ist.

8. Verschluss nach einem der vorherigen Ansprüche, wobei der Schaltbereich von einer Reihe von Punkten gebildet wird.

9. Verschluss nach einem der vorherigen Ansprüche, wobei wenigstens ein Teil des Verschlussdeckels (1) aus einem Fasern enthaltenden Composite-Polymermaterial besteht.

10. Verschluss nach Anspruch 3, wobei die Beschichtung aus einem Polyethylenpolymer besteht.

11. Verschluss nach einem der vorherigen Ansprüche, wobei der Verschlussdeckel einen homogenen Charakter hat.

12. Verschluss nach einem der vorherigen Ansprüche, wobei der Verschlussdeckel hauptsächlich eine kreisförmige symmetrische Gestalt hat.

13. In Kombination einen Verschluss nach einem der vorherigen Ansprüche sowie einen Behälter.

14. Verschlussdeckel (1) für einen Verschluss nach einem der vorherigen Ansprüche.

Revendications

1. Fermeture inviolable pour un récipient (2) tel qu'un bocal, comprenant un capuchon (1) constitué d'un matériau polymère et un moyen (3) destiné à relier le capuchon (1) à un col (4) ou une gorge dudit récipient (2), ledit capuchon (1) comprenant une couronne (5) et une paroi d'extrémité (6) qui peut être amenée dans deux formes d'extrémité, l'une desdites formes d'extrémité étant mécaniquement stable et l'autre forme d'extrémité étant mécaniquement instable, dans laquelle la paroi d'extrémité (6) peut être maintenue dans sa position instable sous l'influence d'une différence de pression entre l'intérieur et l'extérieur lorsqu'elle est connectée au récipient (2), et peut être libérée vers sa position stable en éliminant ladite différence de pression lorsqu'elle est libérée du récipient (2), ledit transfert de la position instable à la position stable étant accompagné par un son audible, dans laquelle le capuchon (1) comprend une partie de capuchon centrale (7), une partie de capuchon en forme d'anneau (8) étant prévue entre ladite partie de capuchon centrale (7) et la couronne (5), la partie de capuchon centrale dans sa forme stable et ladite partie de capuchon en forme d'anneau (8) se coupant l'une l'autre selon un angle d'intersection non égal à zéro dans une coupe radiale de la fermeture, caractérisée en ce que la forme stable de la partie de capuchon centrale (7) est définie par une surface extérieure qui est sphériquement convexe, en ce que l'angle d'intersection α est compris dans la plage de 4° à 15°, en ce que le capuchon (1) possède au moins une zone de commutation qui a une épaisseur qui est égale à 0,1 à 0,9 fois l'épaisseur du reste du capuchon, ladite au moins une zone de commutation permettant le transfert entre les positions instable et stable du capuchon (1), et en ce que le capuchon (1) est constitué d'un matériau polymère de propylène composite.

2. Fermeture selon la revendication 1, dans laquelle le point d'intersection entre la partie de capuchon centrale (7) et la partie en forme d'anneau (8), dans une coupe transversale radiale de la fermeture, a une distance jusqu'à l'extérieur de la couronne (5) qui est au moins égale à l'épaisseur de ladite couronne (5).

3. Fermeture selon la revendication 2, dans laquelle la surface intérieure de la couronne (5) est revêtue, le point d'intersection ayant une distance jusqu'à l'extérieur de la couronne (5) qui est au moins égale à la somme de l'épaisseur de ladite couronne (5) et de l'épaisseur dudit revêtement (9).

4. Fermeture selon la revendication 2 ou 3, dans laquelle le point d'intersection a une distance jusqu'à l'extérieur de la couronne (5) qui est au moins égale à la somme de l'épaisseur de ladite couronne (5) et de l'épaisseur dudit col (4) ou gorge.

5. Fermeture selon l'une quelconque des revendications précédentes, dans laquelle la zone de commutation a une épaisseur qui est égale à 0,2 à 0,8 fois l'épaisseur du reste du capuchon.

6. Fermeture selon l'une quelconque des revendications précédentes, dans laquelle la zone de commutation se situe à la position du point d'intersection.

7. Fermeture selon l'une quelconque des revendications précédentes, dans laquelle la zone de commutation est un anneau continu.

8. Fermeture selon l'une quelconque des revendications précédentes, dans laquelle la zone de commutation est constituée par une série de points.

9. Fermeture selon l'une quelconque des revendications précédentes, dans laquelle au moins une partie du capuchon (1) est constituée d'un matériau polymère composite contenant des fibres.

10. Fermeture selon la revendication 3, dans laquelle le revêtement est constitué d'un polymère de polyéthylène.

11. Fermeture selon l'une quelconque des revendications précédentes, dans laquelle le capuchon est de caractère homogène.

12. Fermeture selon l'une quelconque des revendications précédentes, dans laquelle le capuchon est de forme symétrique principalement circulaire.

13. Combinaison d'une fermeture selon l'une quelconque des revendications précédentes et d'un récipient.

14. Capuchon (1) pour une fermeture selon l'une quelconque des revendications précédentes.

Drawing