GB2199571A

GB2199571A - Closures for containers

Info

Publication number: GB2199571A
Application number: GB08700350A
Authority: GB
Inventors: Nigel Thompson
Original assignee: Metal Closures Ltd
Current assignee: Arconic Closure Systems International UK Ltd
Priority date: 1987-01-08
Filing date: 1987-01-08
Publication date: 1988-07-13
Also published as: GB8700350D0

Abstract

A plastics closure has an internal screw-thread 15 and a tamper-evident ring 14 connected to the bottom edge of the skirt 11 of the closure by frangible bridges 16. For engagement with an annular ridge 23 of the container, the tamper-evident band 14 has a segment 13 spaced radially inwardly of the ring 14 and connected to the ring 14 by a series of flexible connecting ribs 19 which extend obliquely outward from segment 13 to ring 14 in a forward direction relative to the direction of rotation of the closure in applying the closure. <IMAGE>

Description

CLOSURES FOR CONTAINERS This invention relates to closures for containers and is more particularly concerned with screw-threaded closures moulded from plastics materials and having a tamper-evident security band.

According to the invention there is provided a closure moulded from a resilient plastics material and having a top, a depending skirt which has on its internal surface a screw-thread for engagement with a complementary screw-thread on the neck of a container, and a security band comprising a radially outer ring connected to the bottom edge portion of the skirt by a plurality of circumferentially spaced frangible bridges, and one or more circumferentially extending segments spaced radially inward of the outer ring and connected to the outer ring by a plurality of circumferentially spaced connecting portions all of which extend obliquely outward from the or each segment to the outer ring on a forward 4-ir-ection relative to the direction of rotation of the closure in application of the closure.

In one preferred embodiment of the invention, there is one segment only, which segment extends in a substantially complete circle but has a circumferential gap in its periphery. Preferably the segment, or as the case may be one or more of the segments, has intermediate its ends one or more circumferentially extending weakened areas to form a hinge between the two parts of the segment flanking the hinge.

Said connecting portions are conveniently of flat-strip form with their major cross-sectional dimension extending axially of the closure.

According to a preferred feature of the invention, the segment or each of the segments has its radially inner face outwardly chamfered in a direction away from the top.

Some embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a first form of closure according to the invention, Figure 2 shows the closure of Figure 1 in partsectional elevation, and the outline of the container to which the closure is to be applied, Figure 3 is a sectional plan on the line 3-3 of the closure in Figure 2, Figure 3A is a local cross-sectional view on the line 3A-3A of Figure 3, Figure 4 shows the closure at an intermediate stage in its application to the container, Figure 5 is a sectional view on the line 5-5 of Figure 4, Figure 6 shows the closure applied to the container, Figure 7 shows a second form of closure according to the invention, Figure 8 shows a third form of closure according to the invention, and Figure 9 illustrates a modification which is applicable to the closures of Figures 1, 7 and 8.

Referring now to Figures 1 to 4 of the drawings, there is shown a tamper-evident closure having a top 10, a depending skirt 11 and a tamperevident security band 12 which comprises inner and outer rings 13, 14. The closure is moulded in one piece from a suitable thermoplastics material and may have, for sealing the container, a suitable sealing means formed integrally with the closure or some form of sealing liner, as desired. The internal surface of the skirt is formed with a screw-thread ridge 15.The radially inner surface of the outer ring 14 of the security band is substantially axially aligned with the radially outer surface of the skirt, and a series of ribs 16 extend from the external surface of the skirt to the top edge of the ring 14, ribs 16 constituting bridges which are designed to fracture on removal of the closure from the container for which it is intended.

The outer ring 14 is completely circular and the inner ring 13 is almost completely circular but has a-gap 18 in its periphery. The inner ring is connected to the outer ring by a series of hinge elements 19 which extend obliquely outward from the inner ring to the outer ring in a direction inclined forwardly with respect to the direction in which the closure is rotated during application of the closure to a container. The inner ring has an axial groove 20 in its surface at a location diametrically opposite the gap 18, to form a hinge enabling the parts of the ring at opposite sides of the groove 20 to flex inward and outwards relative to each other. The hinge elements 19 are of rectangular cross-section as shown in Figure 3A and have their major dimension extending parallel to the central axis of the closure.The radially inner surface of the inner ring is chamfered outward and downward in its parts further from the top of the closure.

Referring now particularly to Figures 2 and 4, the neck 21 of the container to which the closure is to be applied has a screw thread 22 and, below the screw thread, an annular ridge 23 the radially outer surface 24 of which increases slightly in diameter in a downward direction and the lower edge of which provides a shoulder 25. The internal diameter of the inner ring 13 is such that it can pass over the screw thread ridge on the container as the closure is screwed on to the container neck.As the inner ring 13 moves downward over the surface 24, the hinge groove 20 and gap 18 in the inner ring, and the hinge elements 19 interconnecting the inner and outer rings co-operate to allow the inner ring to expand as shown in Figure 5 until it moves below the shoulder 25 of the ridge on the container, when the resilience of the thermoplastics material causes the inner ring to spring back inward to its former position and into axial abutment with the shoulder 25. When unscrewing movement of the closure commences, the top edge of the inner ring resists upward movement of the whole of the security band, and as the closure is unscrewed, the bridges fracture enabling the upper portions of the closure to be re-moved but leaving the security band on the container.

In the alternative construction illustrated in Figure 7, in which corresponding components are indicated by the same reference numerals as in Figures 1 to 6, the outer ring 14 of the security band initially forms an extension of an increased diameter bottom edge portion 28 of the skirt. A series of ribs 29 spaced about the circumference of the skirt project downward from the internal shoulder formed at the increase of diameter and extend to the radially inner surface of a lower section of portion 28, which section is eventually to constitute the outer ring 14. In this construction, a circumferential slit 30 is cut through or substantially through the skirt at the location of the ribs subsequently to moulding, but the ribs 29 are left intact or substantially so and constitute frangible bridges connecting the security band to the skirt.The security band itself is the same as that described in relation to Figures 1 to 6 and operates in the same manner.

In another alternative construction illustrated in Figure 8, in which corresponding parts arse indicated by the same reference numerals as in Figures 1 to 6, the inner diameter of the outer ring 14 of the security band is greater than the outer diameter of the bottom edge of the skirt, and the outer ring 14 is joined to the skirt only by a series of circumferentially spaced ribs 27 which extend from the bottom edge of the skirt to the inner surface of the outer ring.

These ribs constitute the frangible bridges between the skirt and the security band. The operation of this construction is similar to that of Figures 1 to 6.

Figure 9 illustrates one arrangement of a modification which is applicable to each of the illustrated arrangements. In this modification an additional rib 31 similar to the frangible ribs is provided but is circumferentially much wider, and the outer ring 114 is weakened at a location between the two hinge elements 19 flanking the gap 18. The weakening may be provided by forming an axial groove 32 in either the inner or outer surface or both the inner and outer surfaces of the ring 14. During application of the closure to a cont-ainer, the security band behaves in exactly the same way as described above in relation to Figures 1 to 6. When the closure is removed, however, the frangible bridge elements become fractured but the security band remains anchored to the container at its location below the annular ridge on the container until the outer ring breaks or is broken along its line of weakening or one of its lines of weakening. The security band thus remains attached to the closure on removal of the closure from the container.

It will be understood'that the hinge elements 19 are mechanically weaker than the inner and outer rings 13,14 in order to ensure that flexing of the elements 19 occurs, and not of the rings 13, 14.

The neck of the bottle shown in Figure 2 is formed with a peripheral flange 34 at a location below the annular ridge and this flange serves as a point at which the container can be supported in order to sustain the body of the container against downward forces arising during application of the closure to the container.

If desired, the outer ring 14 can be extended axially, as at 14a in Figure 6, to a point close to this flange so as to impede the insertion of any instrument intended to be used to interfere with the normal operation of the security band.

It will be understood that the angular relationship between the bridges and the hinge elements 19 is immaterial. Similarly the relationship between the number of bridges and the number of hinge elements 19 is immaterial.

Claims

1. A closure moulded from a resilient plastics material and having a top, a depending skirt which has on its internal surface a screw-thread for engagement with a complementary screw-thread on the neck of a container, and a security band comprising a radially outer ring connected to the bottom edge portion of the skirt by a plurality of circumferentially spaced frangible bridges, and one or more circumferentially extending segments spaced radially inward of the outer ring and connected to the outer ring by a plurality of circumferentially spaced flexible resilient hinge elements all of which extend obliquely outward from the or each segment to the outer ring in a forward direction relative to the direction of rotation of the closure in application of the closure.

2. A closure as claimed in claim 1, wherein there is one segment only, which segment extends in a substantially complete circle but has a circumferential gap in its periphery.

3. A closure as claimed in claim 1 or claim 2, wherein the segment, or as the case may be one or more of the segments, has intermediate its ends one or more circumferentially extending weakened areas to form a hinge between the two parts of the segment flanking the hinge.

14. A closure as claimed in any of the claims 1 to 3, wherein said hinge elements are of flat-strip form with their major dimension extending axially of the closure.

5. A closure as claimed in any one of the preceding claims, wherein the or each of the segments has its radially inner face outwardly chamfered in a direction away from the top.

6. A closure as claimed in any one of the preceding claims, wherein said outer ring is further connected to the bottom edge portion of the skirt by a bridge which is circumferentially wider than said frangible bridges and wherein the outer ring is weakened by one or more axial grooves formed therein circumferentially adjacent the wider bridge.

7. A closure as claimed in any one of the preceding claims, wherein the radially inner surface of said outer ring is substantially axially aligned with the radially outer surface of the skirt, and wherein ribs extend from the outer surface of the skirt to the top edge of said outer ring to constitute said bridges.

8. A closure as claimed in any one of claims 1 to 6, wherein the radially inner surface of said outer ring is substantially axially aligned with the radially outer surface of the skirt, and wherein ribs extend from the inner surface of said outer ring to the bottom edge of the skirt to constitute said bridges.

9. A closure as claimed in any one of claims 1 to 6, wherein a circumferential score line is cut to form the division between the outer ring and the skirt, and wherein a plurality of circumferentially spaced ribs extend between the skirt and the inner surface of the outer ring across the location of the score line thereby to constitute said bridges.

10. A closure as claimed in claim 2, wherein the outer ring is weakened at a location between the two hinge elements flanking said gap.

11. A closure as claimed in claim 10, wherein one or more axial grooves are formed in the outer ring at said location thereby to weaken the ring at said location.