GB2445936A

GB2445936A - A cap for removing a closure seal

Info

Publication number: GB2445936A
Application number: GB0701548A
Authority: GB
Inventors: Greif International Holding Bv; Michel Boulange
Original assignee: Greif International Holding BV
Current assignee: Greif International Holding BV
Priority date: 2007-01-26
Filing date: 2007-01-26
Publication date: 2008-07-30
Also published as: GB0701548D0

Abstract

A cap 10 for removing a closure seal of a container comprises a body having a top wall 11 and a side wall 12 downwardly depending from the top wall 11 to a lower rim 13. The top wall 11 has an upstanding cutting member 14 and a centralizing portion 15 comprising of guide members 16. After removing the cap from the container the cap can be inverted and the guide members 16 positioned on the mouth of the container so that when the cap is rotated the centralizing portion guides the rotation of the cutting member to cut an opening to in the seal covering the mouth of the container. The guide members 16 of the centralizing portion 15 is relatively weaker than the top wall of the cap so that when subjected to impact forces as a result of being dropped the guide members 16 of the centralizing portion 15 deform or deflect preventing shearing of the cap. A reinforcing portion 19 may be provided between the top wall and the side wall.

Description

A cap for removing a Closure Seal

Field of Invention

The present invention relates to a closure cap for a container, more particularly to a closure cap having an integral cutting member suitable for cutting a seal covering the mouth of the container.

Introduction

It is commonly known to seal the outlet or mouth of a container with a thin polymeric or metallic membrane or web bonded across the outlet or mouth to prevent tampering, spillage, oxidation, and/or evaporation of the contents of the container. The sealed outlet is then fitted with a resealable closure container cap comprising a body having a top wall and a downwardly extending side wall which fit over the mouth of the container. When the container is opened for the first time, the membrane must be removed or breached by cutting a hole in it. To facilitate the cutting of the seal, a known container cap incorporates cutting members such as a sharp point or knife edge. The cutting members are located in a recess or well formed on the top wall of the container cap which guide the cutting members. When the cap is removed from the container mouth the cap is inverted and located on the mouth of the container such that the cutting members pierce the seal covering the mouth of the container. The recess centralizes the inverted cap over the mouth of the container and guides the cutting member around the seal such that rotation of the cap cuts a neat opening in the seal.

The recess is defined by a continuous ring upstanding from the top wall of the cap and surrounding the cutting members. This ring forms a continuation of, and is in alignment with the cap side wall. The continuous ring formed by the recess is relatively rigid due to its wall thickness in relation to the rest of the body of the container cap, particularly the top wall. The joint between the cap top wall, the side wall and the upstanding wall of the centralizing portion thus forms a stress concentration area. Moreover any impact force experienced by the centralizing portion will be transferred to the stress concentration area, with reaction forces from the container neck acting on the edges of the cap wall together with the impact forces to subject the stress concentration area to very high shear forces, much like a punch and die. Such caps therefore often fail drop tests in which a full container is dropped at angle of 450 so that the cap impacts the ground. Similar failures result from rough handling of such containers and caps in actual use.

s Thus there is a need to provide a centralising portion on the outer surface of a container cap for guiding a cutting member without introducing stress concentration areas vulnerable to shearing when a container is dropped onto its cap or the cap experiences other high impact forces. At the same time the cap should remain economical to manufacture.

Summary of Invention

The present applicant has mitigated the above problems by providing a cap for a container, comprising a body having a top wall and a side wall downwardly depending from the top wall, the top wall having a protruding cutting member and a centralizing portion so that in use in an inverted state the centralizing portion can be located on the mouth of the container and the cap can be rotated such that the centralizing portion guides the rotation of the cutting member to cut an opening in a seal covering the mouth of the container, wherein the centralizing portion is relatively weaker than the top wall of the cap.

By providing a centralizing portion that is weaker than the top wall of the cap any stress concentrated areas in the vicinity around the centralizing portion are made less vulnerable to shearing such that any impact forces experienced by the cap are diffused more effectively within the body of the cap, i.e. the punching effect of the centralizing portion and container neck into the top of the cap is reduced. Instead the impact force compresses the material of the cap against the container neck. Moreover, the centralizing portion in some embodiments may help to cushion the impact force minimizing any transfer of stress to the body of the cap, particularly at the shoulder between the top wall and the side wall of the container cap.

Preferably the centralizing portion comprises a plurality of protruding guide members on the top wall of the cap. Preferably the protruding guide members are arcuate so to form a discontinuous ring surrounding the cutting member. This advantageously makes the cap more flexible since the guide members can deflect individually and any rigidity as a result of a continuous ring having relatively a thick wall is thus removed.

Equally the centralizing portion may be a continuous ring member on the top wall of the container. By making the wall thickness of the centralizing portion relatively thin in comparison to the wall thickness of the top wall any impact force will cause the wall of the S centralizing portion to deflect and thus reduces shearing of the top wall of the cap at the shoulder formed with the cap side wall.

Preferably the shoulder of the cap between the top wall and the side wall has an internal reinforcement to provide support to the shoulder against impact forces. I0

The top wall maybe generally thickened, e.g. up to about 3mm in a 63mm internal diameter cap, compared to 1.8mm for known screw caps of this diameter.

The outer surface of the side wall may have a plurality of spaced apart ribs extending substantially between the top wall and a lower rim of the cap. Extending the rib substantially to the top wall of the cap provides further support to the shoulder of the cap against impact forces and shearing. Preferably the ribs merge with the top wall to form a radius substantially in the range of 2mm to 5mm, preferably in the range substantially between 3mm to 4mm, more preferably substantially 2.9mm. This offers a wide impact radius and thus impact area when subjected to a 45 drop test so as to dissipate the impact forces and avoid concentration of shear forces.

Optionally the cap lower rim is provided with a reinforcement having a height extending up the side wall of the cap. More preferably the reinforcement is in form of a continuous band around the lower rim of the container cap. The reinforcing band or ring reduces the risk of the cap detaching from the mouth of the container (e.g. popping off container neck threads) and thus provides a good support for gripping onto the neck of the container.

Preferably the centralizing portion is integrally formed, e.g. moulded, with the body of the cap and thus can be economically manufactured without any additional expense in relation to existing caps.

Brief Description of the Drawings

Further preferred features of the present invention will be apparent from the claims and the following description of the illustrative embodiments, made with reference to the accompany drawings in which: Fig I is a perspective view of the cap according to an embodiment of the present invention; Fig 2 is a cross sectional view of the cap along the line A-A in Fig. 1, shown during a drop test; Fig 3 is a side view of the cap showing the spaced apart ribs on the side wall outer surface; and Fig 4 is a part sectional view of the container cap showing the reinforcing ring at the lower rim, and the thickened top wall.

Description of Illustrative Embodiments

The cap 10 according to an embodiment of the present invention shown in Fig 1, has a top wall 11 and a sidewall or skirt 12 downwardly depending from the top wall 11 to a lower rim 13 for fitment onto the neck of a container. The top wall 11 has a radially inner upstanding cutting member 14 in the form of sharp point or knife edge suitable to pierce the seal covering the mouth of the container. The seal in the form of a sealing membrane is usually fused to the rim of the neck of the container by induction welding. Surrounding the cutting member 14 is a centralizing portion 15 in the form of a plurality of arcuate upstanding guide members 16. The height of the guide members 16 is substantially between 1mm to 5mm, preferably 2mm to 4mm, more preferably 3mm. When the cap is placed upside down on the mouth of the container the upstanding guide members 16 of the centralizing portion 15 engage snugly over the container mouth and guide the cutting member 14 around the seal covering the mouth of the container in order to cut a neat circular opening in the seal.

The wall thickness of the guide members 16 is relatively small in comparison to the thickness of the top wall 11 and side wall 12 of the cap (see Fig 2). Thus the guide members 16 will deflect or deform when subject to impact forces such as when a container fitted with the cap is dropped cap downwards onto a hard surface such as the ground, limiting any shearing effect in the vicinity of the guide members 16. An advantage of the thinner discontinuous ring is that the impact resistance of the ring in a 45 drop test as shown in Fig. 2, or against similar impacts, is almost non-existent in comparison to the stiffness of the cap walls. Previously known caps have a thicker and taller cutter centralising ring which creates a greater impact resistance when dropped and transmits the ground impact, in combination with the reaction force from the container neck leading to high shear in the stress concentration area at the junction between the cap top wall and the cap side wall/centralising ring. By reducing the centralising ring thickness and introducing discontinuities, it is made very much weaker than the adjacent cap side wall. The shearing effect is therefore substantially eliminated in the drop test and similar impacts, becoming a compression force between the ground etc. and the neck of the container. The cap material is much better able to withstand compression without rupture, compared to shear stress, particularly if the shoulder region and optionally the cap top wall generally are strengthened by thickening or other means. Other reinforcement can be used, such as metal mesh or higher strength (e.g. glass or aramid) fibre inserts.

The top wall 11 of the cap shown in section in Fig. 2 is thickened to provide support to the cap 1 when subject to the impact forces. Typical thickness of the top wall for a 63mm internal diameter cap is preferably greater than 1.8mm, more preferably 3mm. The top walls of caps of other diameters can be proportionally thickened. The side wall 12 is also shown with an internal thread 17 for engaging with the neck of a container. Means for securing the container cap onto the container neck is not limited to threading and other securing means such as a snap-on arrangement are permissible.

The shoulder area 18 of the cap at the junction between the top waIl 11 and the side wall 12 is reinforced by an internal thickened chamfer 19 or larger than usual internal radius to provide support to the cap 10 when fully installed on the neck of the container. For further support to the shoulder area or upper corner of the cap gripping means are provided on the outside of the cap, see Fig 3, represented by a plurality of vertical spaced apart ribs 20 which extend axially along the side wall between the lower rim 13 all the way up to the top wall 11 of the cap. These taller than usual ribs 20 reinforce the shoulder area which is vulnerable to shearing. The ribs 20 may substantially run the entire height of the cap 10 and merge with the top wall 11 to form a radius substantially in the region of between 2mm to 5mm, preferably substantially between 3mm to 4mm, more preferably 2.9mm. This offers a wider impact radius than conventional caps and thus impact area when subjected to a 45 drop test so as to dissipate the impact forces and avoid concentration of shear forces.

To prevent the cap 10 from detaching from the neck of the container by deformation in the hoop direction, the lower rim 13 of the cap 10 is provided with a reinforcement ring or band 21 whose height extends up the sidewall 12. Also shown in Fig. 4 is an anti-tamper ring 22 frangibly connected to the cap body and having inwardly directed ratchet fingers. These engage in the usual way with ratchet teeth (not shown), formed on the container neck.

Claims

Claims 1. A cap for.a container, comprising a body having a top wall

and a side wall downwardly depending from the top wall, the top wall having a protruding cutting member and a centralizing portion so that in use in an inverted state the centralizing portion can be located on the mouth of the container and the cap can be rotated such that the centralizing portion guides the rotation of the cutting member to cut an opening in a seal covering the mouth of the container wherein the centralizing portion is relatively weaker than the top wall of the cap.
2. A cap as claimed in Claim I wherein centralizing portion comprises a plurality of protruding guide members on the top wall of the cap.
3. A cap as claimed in Claim 2 wherein the protruding guide members are arcuate.
4. A cap as claimed in Claim I wherein the centralizing portion is a continuous ring member on the top wall of the container.
5. A cap as claimed in Claim 1, 2 or Claim 3 wherein the centralizing portion is a discontinuous ring on the top wall of the container.
6. A cap as claimed in any of the preceding claims wherein the shoulder of the cap between the top wall and the sidewall has an internal reinforcement.
7. A cap as claimed in any of the preceding claims wherein the outer surface of the side wall has a plurality of spaced apart ribs extending substantially between the top wall and a lower rim of the cap.
8. A cap as claimed in Claim 7 wherein the ribs merge with the top wall to form a radius substantially in the range of 2mm to 5mm, preferably in the range substantially between 3mm to 4mm, more preferably substantially 2.9mm.
9. A cap as claimed in any of the preceding claims wherein the centralizing portion is integrally formed with the body of the cap.
10. A cap as claimed in any of the preceding claims wherein the top wall has a thickness of substantially greater than 1.8 mm, preferably 3mm.
11. A cap as claimed in any of the preceding claims wherein a lower rim is provided with a reinforcement ring having a height extending up the side wall of the cap.
12. A cap as claimed in any of the preceding claims wherein the height of the guide members are substantially between 1mm to 5mm, preferably between 2mm to 4mm, more preferably 3mm.
13. A cap as claimed in any of the preceding claims and substantially described herein with reference to and as shown in the accompany drawings.