WO2008095863A1

WO2008095863A1 - Tamper evident closure and container for receiving tamper evident closure and combination thereof

Info

Publication number: WO2008095863A1
Application number: PCT/EP2008/051222
Authority: WO
Inventors: Sebasten Cedric Widmer; Lino Dreyer; Juilen Rouchon
Original assignee: Obrist Closures Switzerland Gmbh
Priority date: 2007-02-08
Filing date: 2008-01-31
Publication date: 2008-08-14

Abstract

A container assembly comprising a container finish and a tamper evident closure in sealing contact. The tamper evident closure (10) having a lower tamper evident band (18) frangibly connected to an upper body portion (16) and inwardly protruding projections (22) positioned on the tamper evident band (18). The projections are configured to engage with corresponding retaining projections (30) on the outer surface of the container finish (28). Such engagement occurs when an axially rotational force is applied to the closure in an opening direction, resulting in the tamper evident band (18) rupturing from the upper body portion (16) before the sealing contact is broken.

Description

Tamper evident closure and container for receiving tamper evident closure and combination thereof

This invention relates generally to the field of packaging technology, and in particular to tamper evident closures for containers .

It is common practice for beverages and some foods and medicines to be delivered to the public in bottles or other containers that are provided with re-sealable closures. Although resealable containers provide benefits to consumers, by their nature they permit unauthorised and sometimes undetectable tampering with the product .

Accordingly, there is a requirement in the packaging industry for closures for bottles and other resealable containers to be provided with some form of tamper-evident feature, which are designed to make it apparent to a consumer that a container has been opened. Many conventional tamper evident closures utilise what is known as a tamper evident band. Commonly, the tamper evident band is connected to the lower edge of the skirt portion of the closure by a line of weakness, for example, frangible bridges or a scored line. The tamper evident band rests beneath a retaining structure, such as an annular ledge, on the container finish and the annular ledge is located below a threaded section of the container finish. A retaining element such as a radially inwardly directed flange or folded flaps on the inner face of the tamper evident band prevents the tamper evident band from being removed due to engagement of the retaining element with the annular ledge when the closure is unscrewed for removal. This means that there is some resistance to unscrewing of the closure, until the line of weakness or bridges fracture, consequently allowing easy removal of the closure, with the tamper evident band remaining in position below the annular ledge.

In another known closure, commonly referred to as a "pig-tail closure", the line of weakness between the tamper evident band and the skirt portion of the closure does not continue around the entire circumference. Consequently, when the consumer unscrews the closure, the line of weakness fractures and the tamper evident band breaks, allowing removal of the closure with the tamper evident band still attached to a section of the skirt portion of the closure.

US Patent Number 5,860,542 to Takamatsu discloses a sealing device having erectable engaging projections on an inner surface of a tamper evident ring. The container finish comprises an annular expanded portion beneath an external thread having at least one depressing portion formed on the expanded portion which engages the erectable engaging portions when the consumer turns the closure in a closure opening direction.

However, the tamper evident band and the retaining structure of the container have to be designed such that the tamper evident band will slip over the retaining structure without damage during the initial application of the closure onto the container at the packaging plant.

A problem associated with such closures results from the inherent elasticity of some types of plastic materials. If the closure is slowly and carefully slightly unscrewed, it may be possible, particularly at elevated temperatures, to stretch the bridges so that the closure seal to the contents of the container opens prior to the bridges breaking. This would enable contamination of the container contents through the open seal. Subsequently returning the closure to its original position would mean that the contamination was not evident to the consumer .

A need, therefore, exists for an improved closure structure that reduces the likelihood of the closure seal being broken without separation of the tamper evident band from the rest of the closure .

A further problem associated with such closures is related to the retaining structure for the tamper evident band. The retaining structure, generally a continuous annular ledge around the container finish, substantially increasing the diameter of the finish. Hence, during the bottling process when the closure is initially applied, it is necessary to expand and distort the tamper evident band in order to pass it over the retaining structure on the finish. This process weakens the whole closure structure and in particular the bridges, thus leading to the possibility that the bridges break during application.

Therefore, a need exists to provide a container assembly having a tamper evident closure for which the weakening of the closure during application to the finish is reduced.

A primary object of the present invention is to provide a tamper evident feature which overcomes the drawbacks of the prior art. Specifically, the present invention provides a construction of a container finish and closure therefore which has a tamper evident closure, and does not allow the closure seal to be broken without separation of the tamper evident band from the rest of the closure. Further, the present invention seeks to provide a tamper evident closure for which the weakening of the closure during application to the finish is reduced, and also destruc- tion of the bridges during application is avoided.

According to a first aspect of the invention there is provided a tamper evident closure for a container finish, the closure comprising an upper body portion and a lower tamper evident band frangibly connected to the upper body portion, the tamper evident band having at least one inwardly protruding projection, wherein the projection has a ramp on the surface directed towards the upper body portion, and the ramp is configured to engage with a corresponding retaining projection on the container finish .

According to one embodiment of the invention, the inwardly per- truding projection may be arranged on an inner surface of the tamper evident band. In an alternative embodiment, it is also possible to provide a tamper evident band with an inwardly fold- able surrounding ring. In such a case, the projection will be arranged on the radially inwardly directed surface of the ring when the ring is in its upwardly folded position. Such a design can be easily moulded with a downwardly extending ring. In such a case, the projection is moulded on a radially outwardly directed surface of the foldable ring in its downwardly, unfolded position .

Advantageously, the projections are designed to slip over the corresponding retaining projections during initial application of the closure to the container finish.

The ramp may comprise the leading edge of the projection when the closure is rotated in an opening direction and preferably, the ramp has an angle of inclination of around 30 degrees from the radial axis. Further, the tamper evident closure may com- prise several projections regularly located on the inner circumference of the tamper evident band.

Preferably, the closure further comprises a threaded section on the inner surface of the upper body portion, wherein the pitch of the threads in the threaded section and the position of the threads relative to the projections are arranged such that the projections engage with the corresponding retaining projection on the container finish when an axially rotational force is applied to the closure in an opening direction.

Advantageously, the application of a minimal rotational force to the upper body portion of the closure will rupture the bridges before the seal between the closure and the container finish is broken .

According to a second aspect of the invention there is provided a container for receiving a tamper evident closure, the container comprising a finish having at least one outwardly protruding retaining projection, wherein the retaining projection has an inverted ramp on the surface directed away from the finish opening, and the inverted ramp is configured to engage with a corresponding projection on the tamper evident closure.

Advantageously, the total increase in the outer circumference of the container finish due to the retaining projections is minimal. Consequently, it is not necessary to substantially expand and distort the tamper evident band in order to pass it over the retaining projections when initially applying the closure to the container .

Preferably, the inverted ramp comprises the edge of the retaining projection that first engages the corresponding projection on the tamper evident closure when the closure is rotated in an opening direction. Further, the ramp may have an angle of inclination of around 30 degrees from the radial axis. In a preferred embodiment, the container may comprise several of the retaining projections regularly located on the outer circumference of the container finish. Preferably, the container further comprises a threaded section on the outer surface of the finish, wherein the pitch of the threads in the threaded section and the position of the threads relative to the retaining projections are arranged such that the retaining projection engages with the corresponding projection on the tamper evident closure when an axially rotational force is applied to the closure in an opening direction .

Advantageously, during the axial rotation, the ramp surfaces would slide across one another effectively resisting the rotational force and causing the tamper evident band to forced axially downwards. This action would cause the bridges to break, thereby releasing the upper body portion of the closure.

According to a third aspect of the invention there is provided a container assembly, comprising the container of the first aspect and the tamper evident closure of the second aspect, wherein the original application of the tamper evident closure to the container finish positions the tamper evident band projection below the retaining projection of the container finish such that the ramp surface of the tamper evident band projection is complementary to and adjacent the inverted ramp surface of the corresponding retaining projection of the container finish.

Advantageously, it is not necessary to substantially expand and distort the tamper evident band in order to pass it over the retaining projections when the closure is initially applied to the container. Thus, no weakening of the structure or material of the closure results.

Preferably, the finish opening further comprises an annular sealing surface which is in sealing contact with the inner surface of the tamper evident closure and wherein the tamper evident band ruptures from the upper body portion before the sealing contact is broken when an axially rotational force is applied to the closure in an opening direction. Further, the inner surface of the upper body portion of the closure and the outer surface of the container finish may be engaged by one of a single thread formation, a multi thread formation or a bayonet formation .

Advantageously, the closure seal of the container will not open until after the tamper evident band has become separated from the closure. Therefore, it is not possible for the container contents to be contaminated without it being evident to the consumer that the container assembly had been tampered with.

A preferred embodiment of the present invention is now described by way of example with reference to the accompanying drawings, in which;

Figure 1 shows a tamper evident closure;

Figure 2a illustrates a tamper evident band according to an embodiment of the present invention;

Figure 2b shows a cross sectional view of the tamper evident band with additional marking to indicate the angle of inclination of a ramp of one of the projections; Figure 3a illustrates a container finish according to an embodiment of the present invention;

Figure 3b shows a side view of the container finish with additional marking to indicate the angle of inclination of an inverted ramp of one of the projections;

Figure 4 illustrates a part of the container assembly comprising the tamper evident band of Figures 2a and 2b, engaged with the container finish of Figures 3a and 3b;

Figure 5a shows a cross sectional view of the closure according to a preferred embodiment of the present invention;

Figure 5b illustrates a container finish according to a preferred embodiment of the present invention;

Figure 5c illustrates a part of the container assembly comprising the projections of the tamper evident band of Figure 5a, engaged with the container finish of Figure 5b.

Figure 6 depicts a part of the container assembly according to a further preferred embodiment, showing only the projections of the tamper evident band engaged with the container finish.

Figure 7a shows the cross-section or view of a closure according to another embodiment of the invention and figure 7b shows a container finish for the closure shown in figure 7a.

Referring to the drawings, like reference numerals designate corresponding features throughout the views. Figure 1 illustrates a tamper evident closure 10 having an upper body portion 12 which has a base 14 and a downwardly depending annular sidewall portion 16. The closure 10 further includes a tamper evident band 18 that is frangibly connected to the side- wall portion 16 by a plurality of breakable bridges 20. The outer of surface of the upper body portion 12 may include a surface designed to improve grip when the consumer is unscrewing the closure 10. In a preferred embodiment, the closure is preferably manufactured from plastics, such as PP or HDPE, by injection-molding or compression moulding.

Figure 2a shows an embodiment of the tamper evident band 18 which has four inwardly protruding projections 22 regularly spaced around the inner circumferential surface of the tamper evident band 18. In this embodiment, which is constructed according to a preferred embodiment of the invention, each projection 22 has a single form comprising a ramp section 24 and a rectangular section 26 when viewed in a radial direction. When the closure is being rotated in the direction for unscrewing, the ramp section 24 is at the leading edge and the rectangular section 26 is at the trailing edge. The ramp 24 starts at the lower face of the projection 22 and terminates at the upper face of the projection, thereby forming a ramp 24 on the upper side of the projection 22. Whilst it is not shown in this illustration, the bridges 20 illustrated in Figure 1 would, in use, be seen extending from the upper edge of the tamper evident band 18. The breakable bridges 20 can be formed by moulding during moulding of the closure. It is, however, also possible to preform bridges on the inner surface of the closure and to slit a score line in a manner known to those skilled in the art after demoulding of the closure. It is furthermore possible to use any way of frangible line known to those skilled in the art in context with the present invention. In the case of frangible bridges, the bridges are preferably uniformly arranged along the circumference of the closure with respect to the projections 22. A uniform distribution as compared to the projections leads to a uniform breaking off the bridges. Preferably, bridges are axi- ally aligned with respect to each of the projections 22. In the spaces between neighbouring projections, additional frangible bridges may be uniformly distributed. During opening, the highest force will be initially created neighbouring the projection 22 which will lead to distraction of the breakable bridegs closest to the projection 22 first.

Figure 2b is a cross-sectional diagram of the tamper evident band 18 which includes an extra diagrammatical marking to indicate the angle of inclination of the ramp 24 of one of the projections 22. In a preferred embodiment the form of each of the projections 22 is substantially the same. The angle of inclination of the ramp 24 is at approximately 30 degrees to the horizontal. The closure is preferably manufactured from plastics, such as PP or HDPE, by injection-molding or compression moulding.

Figure 3a shows an embodiment of the container finish 28 which has four outwardly protruding retaining projections 30 regularly spaced around a lower portion of the outer circumferential surface 32 of the finish 28. In this embodiment, which is constructed according to an embodiment of the invention, each retaining projection 30 has a single form comprising an inverted ramp section 34 and a rectangular section 36 when viewed in a radial direction. When the closure is being rotated in the direction for unscrewing, the inverted ramp section 34 is at the leading edge of the retaining projection ie. it engages first with the associated projection on the tamper evident band, and the rectangular section 36 is at the trailing edge. The inverted ramp 34 starts at the upper face of the retaining projection 30 and terminates at the lower face of the retaining projection 30, thereby forming an inverted ramp on the underside of the retaining projection 30. An annular sealing surface 38 is located at the top edge of the finish 28. Whilst it is not shown in this illustration, the upper portion of the outer circumferential surface 32 of the finish 28 would preferably have a single thread formation, a multi thread formation or a bayonet formation in order that it can engage with a complementary formation on the inner surface of an upper body portion 16 of the closure 10.

The inner surface of the base 14 of the closure 10 forms a seal with the annular sealing surface 38. The closure 10 may be a liner closure or alternatively a one-piece closure engaging with a plug type seal or another suitable type of closure Depending on the specific application, minor closures or one piece closures may be preferred. The sealing will be designed in such a way as to ensure a seal at least until the time when the tamper evident band has been detached from the sidewall portion of the closure, i.e. until the breakable bridges have been broken.

Figure 3b is a side-view diagram of the container finish which includes an extra diagrammatical marking to indicate the angle of inclination of the inverted ramp 34 of one of the retaining projections 30. In a preferred embodiment the form of each of the retaining projections 30 is substantially the same. The angle of inclination of the inverted ramp 34 is at approximately 30 degrees below the horizontal. The finish is preferably manufactured from plastics, such as PET, by injection-molding.

Figure 4 illustrates a part of the container assembly. The container finish 28 and the tamper evident band 18 are shown in or- der to illustrate the relative position of the projections 22 and the retaining projections 30 when the closure finish 28 is sealed. Thus, the original application of the closure 10 to the container finish 28 in, for example, a bottling plant, positions the tamper evident band projection 22 below the retaining projection 30 of the container finish 28 such that the ramp surface 24 of the tamper evident band projection 22 is complementary to and adjacent the inverted ramp surface 34 of the corresponding retaining projection 30 of the container finish 28. Here, the term adjacent means either directly next to or at some distance, for example several millimetres distance.

It is assumed that the container finish 28, the tamper evident band 18 and their associated projections 30 22, although not clearly seen in Figure 4, are of the same form as shown in the proceeding figures. Thus, in use, a consumer would apply a rotational force in the direction of arrow A to the upper body portion 16 of the closure 10 in order to unscrew the closure. During the rotation, the projections 22 30 would initially be forced into an engaging contact between their respective ramp surfaces 24 34. Then the ramp surfaces 24 34 would slide across one another effectively resisting the rotational force in the direction of arrow A by causing the tamper evident band 18 to forced axially downwards. This action would cause the bridges 20 to break, thereby releasing the upper body portion 16 of the closure 10 and enabling the upper body portion 16 to be completely unscrewed from the finish 28. Accordingly, separation of the tamper evident band 18 from the upper body portion 16 is assured even when the rotational force applied to the upper body portion of the closure is minimal.

Subsequently, the consumer may reseal the container assembly by screwing the upper body portion 16 of the closure back onto the finish 28 and this action is in no way impeded by the presence of the tamper evident band 18. Furthermore, in a preferred embodiment the finish 28 is designed such that the tamper evident band 18 falls a distance down the finish towards the body of the container. Consequently, there is a visible gap between the ruptured tamper evident band 18 and the sidewall portion 16 of the closure 10 providing the consumer with easily visible evidence that the container assembly has been tampered with.

When the tamper evident closure 10 is originally applied to the container finish 28, a seal is formed between the annular sealing surface 38 located at the top edge of the finish and a part of the inside of the container finish, preferably the uppermost edge of the container finish. Thus, the seal will be broken if the upper portion 16 of the closure is moved axially upwards with respect to the container finish 28. As explained in the foregoing description, the application of a minimal rotational force to the upper body portion of the closure will rupture the bridges. Importantly, this means that the axial displacement of the upper body portion 16 of the closure resulting from the rotational movement is also minimal and hence the seal is maintained at least until the bridges have ruptured.

Figure 5a is a cross sectional view of a closure 10 also showing two projections 22 on the far side of the tamper evident band 18. Each projection 22 of this preferred embodiment comprises a tapered body having an upper ramp surface 24. The profile of the inner surface of the base 14 illustrates a so-called one-piece closure enabling a plug-type seal with the annular sealing surface of the container finish.

Figure 5b illustrates a container finish having an arrangement of threads 40 positioned on the finish and retaining projections 30 according to a preferred embodiment of the present invention. Each retaining projection 30 has an inverted ramp surface 34 directed away from the top edge of the container finish 28. In this preferred embodiment, the thread design has two complete circumlocutions of the finish and the upper surface of each retaining projection is substantially parallel to the lower ramp surface. The inclined ramp surfaces 24, 34, will create forces into directions during removal of the closure. A first force is created in circumferential direction. This force leads to a stretching of the breakable bridges in circumferential direction. Because of this force, the opening moment for removing the closure is slightly increased. The ramp surfaces further create a force in the axial direction. This force leads to axial stretching of the bridges. This axial force does not substantially increase the opening moment of the closure during removal. Compared to standard ratchet designs where forces are only created in the circumferential direction, the present invention reduces the opening moment and thus facilitates handling by the user.

Figure 5c shows the position of the projections 22 of this preferred embodiment with respect to the retaining projections 30 on the container finish of the preferred embodiment. It is noted that the respective ramp surfaces 24 34 have complementary positions and are illustrated in close proximity to one another.

A further preferred embodiment of the present invention is shown in Figure 6. A container finish is shown having an arrangement of threads 40 positioned on the finish 28 and three of the four retaining projections 30 on the finish are visible. Each retaining projection 30 has an inverted ramp surface 34 directed away from the top edge of the container finish 28. A minor portion of the inverted ramp surface at the leading end and the trailing end is substantially parallel to the top edge of the finish. In this further preferred embodiment, the upper surface of each retaining projection is also substantially parallel to the top edge of the finish 28. Of the tamper evident band, only the projections 22 are illustrated in Figure 6. Each projection 22 of this preferred embodiment comprises a tapered body having an upper ramp surface 24, where at least half of the trailing portion of the projection 22 has upper and lower edges which are substantially parallel to the top edge of the finish 28. The projections 22 of the tamper evident band are shown in engaging contact with the retaining projections 30.

Upon initial application of the closure 10 to the container finish 28, the projections 22 are designed to slip over the retaining projections 30. This slipping action is particularly facilitated by the rounded, smooth form of the projections 22 30 illustrated in the embodiments of Figures 5a-5c and Figure 6.

The total increase in the outer circumference of the container finish due to the retaining projections is minimal. As a result, it is not necessary to substantially expand and distort the tamper evident band in order to pass it over the retaining projections when applying the closure to the container. Preferably, a minimum of pressure applied to the closure to cause a slight modification in the closure form to a polygon is adequate for the closure to be applied to the finish. In this way, no weakening of the structure or material of the closure results. In contrast, the total increase in the outer circumference of the container finish due to the annular ledge of the prior art is substantial. Thus it is necessary to expand the closure form in order to apply the closure to the finish. Such expansion may result in damaging or weakening the structure or material of the closure . It will be appreciated by those skilled in the art that various modifications and alternatives to the features of the above described embodiments could be envisaged in light of the overall teachings of the description. Accordingly, the particular embodiment described is illustrative only and not limiting as to the scope of the invention.

The design in figure 7a substantially corresponds to the closure shown in figure 5a with the only difference that the projections 220 are arranged on a upwardly folded ring 25 attached to the lower edge of the tamper evident band 18. In the upwardly folded position of the ring 25, the projections are directed radially inwardly. The projections can be moulded on the ring 25 in a downwardly unfolded position so as to extend radially outwardly in the ...moulded position. Such a design is easier to be moulded.

In general, the pitch of the threads, the kind of the seal used and the arrangement and design of the projections 23 shall be selected in combination such as to achieve the desired result. In particular, the design of the seal should be made in a manner such that the seal only breaks after the breakable bridges 20 are broken. Because of the additionally used axial force on the bridges, the bridges break relatively quickly even if the pitch of the thread is relatively low. In particular, the thread can have a pitch of 2,8 (i.e. an axial movement of 2,8mm upon one turn of the closure) which is relatively low as compared to standard closures. Because of this relatively low pitch, the seal can be maintained for a relatively long time. Thereby, breaking of the bridges before disruption of the seal can be ensured. In case of closures used for carbonated beverages, appropriate venting systems can be used. Such systems are known to those skilled in the art.

Claims

1. A tamper evident closure (10) for a container finish (28), the closure (10) comprising an upper body portion (16) and a lower tamper evident band (18) frangibly connected to the upper body portion (16), the tamper evident band (18) having at least one inwardly protruding projection (22), wherein the projection (22) has a ramp (24) on the surface directed towards the upper body portion, and the ramp (24) is configured to engage with a corresponding retaining projection (30) on the container finish (28).

2. A closure as claimed in claim 1, wherein the ramp (24) comprises the leading edge of the projection (22) when the closure (10) is rotated in an opening direction.

3. A closure as claimed in claim 2, wherein the ramp (24) has an angle of inclination of around 30 degrees from the radial axis .

4. A closure as claimed in claims 2 or 3, comprising several projections (22) regularly located on the inner circumference of the tamper evident band (18) .

5. A closure as claimed in claim 4, further comprising a threaded section on the inner surface of the upper body portion (16), wherein the pitch of the threads in the threaded section and the position of the threads relative to the projections (22) are arranged such that the projections (22) engage with the corresponding retaining projection (30) on the container finish (28) when an axially rotational force is applied to the closure in an opening direction.

6. A container for receiving a tamper evident closure (10), the container comprising a finish (28) having at least one outwardly protruding retaining projection (30), wherein the retaining projection (30) has an inverted ramp (34) on the surface directed away from the finish opening, and the inverted ramp (34) is configured to engage with a corresponding projection (22) on the tamper evident closure (10) .

7. A container as claimed in claim 6, wherein the inverted ramp (34) comprises the edge of the retaining projection (30) that first engages the corresponding projection (22) on the tamper evident closure (10) when the closure is rotated in an opening direction.

8. A container as claimed in claim 7, wherein the ramp (24) has an angle of inclination of around 30 degrees from the radial axis .

9. A container as claimed in claim 7, comprising several of the retaining projections (30) regularly located on the outer circumference (32) of the container finish (28) .

10. A container as claimed in claims 8 or 9, further comprising a threaded section on the outer surface of the finish (28), wherein the pitch of the threads in the threaded section and the position of the threads relative to the retaining projections are arranged such that the retaining projection (30) engages with the corresponding projection (22) on the tamper evident closure (10) when an axially rotational force is applied to the closure in an opening direction.

11. A container assembly, comprising a container as claimed in any of claims 6 to 10, and a tamper evident closure (10) as claimed in any of claims 1 to 5, wherein the original application of the tamper evident closure (10) to the container finish (28) positions the tamper evident band projection (22) below the retaining projection (30) of the container finish (28) such that the ramp surface (24) of the tamper evident band projection (22) is complementary to and adjacent the inverted ramp surface (34) of the corresponding retaining projection (30) of the container finish (28) .

12. A container assembly as claimed in claim 11, wherein the finish opening further comprises an annular sealing surface (38) which is in sealing contact with the inner surface of the tamper evident closure (10) and wherein the tamper evident band (18) ruptures from the upper body portion (16) before the sealing contact is broken when an axially rotational force is applied to the closure in an opening direction .

13. A container assembly as claimed in claim 12, wherein the inner surface of the upper body portion (16) of the closure

(10) and the outer surface (32) of the container finish (28) are engaged by one of a single thread formation, a multi thread formation or a bayonet formation.