EP4400444A1

EP4400444A1 - Container closure overcap

Info

Publication number: EP4400444A1
Application number: EP23157040.9A
Authority: EP
Inventors: Dale Taylor; Pedro DE OLIVEIRA
Original assignee: Greif International Holding BV
Current assignee: Greif International Holding BV
Priority date: 2023-01-13
Filing date: 2023-02-16
Publication date: 2024-07-17

Abstract

A molded plastics overcap 10 for a container closure comprises a top wall 12, a generally annular side wall 14 depending from the top wall 12, and a retention skirt 16 foldably attached to a rim 18 of the side wall 14. The retention skirt 16 is foldable between a first position in which it extends from the side wall 14 away from the top wall 12, to an operative position in which it extends within the side wall 14 towards the top wall12. The retention skirt 16 comprises a retention boss 20 which, when the retention skirt 16 is in the operative position, extends radially inward and provides an engagement surface 22 facing the top wall 12 so as to be engageable beneath a closure flange 26 retaining curl 24 to retain the overcap 10 thereon. The retention skirt 16 further comprises a locking projection 18 which projects towards the top wall 12 radially outward of the engagement surface 22 when the retention skirt 16 is in the operative position within the side wall 14. The overcap 10 may also comprise frangible tamper evidencing features 36, 38a, 38b, 40.

Description

Field of the invention

The present invention concerns a molded plastics overcap for a container closure.

Background of the invention

Such overcaps are typically used to provide a degree of tamper resistance and physical protection for a container closure, such as a closure plug for a "200-litre" ("55 U.S. gallon") steel drum or similarly sized industrial container. The overcap may for example restrict access to the plug extraction features and shield the plug against dirt and water ingress. The overcap may be designed to be broken upon removal, whereby the presence of an undamaged overcap provides some assurance that the container contents have not been interfered with in the supply chain.
Current polymer tamper evident overcaps used to protect the contents of steel drums rely on an internally projecting annular retention boss engageable beneath the drum closure flange retaining curl. Historically polymer tamper evident overcaps have been designed with a retention boss geometry that allows the overcap to be injection molded and then removed from the mold by being stripped away from the core tooling. To facilitate removal from the injection mold tooling the retention boss has a ramp angle that enables the overcap to expand out of the internal retention boss undercut in the core tooling without permanent deformation. See US 7,080,749B2 , US7,568,585B2 , WO2005/056412A1 and USD963,811S1 for example. However, this angled retention feature also allows a determined individual a relatively easy means of prying the overcap off the drum opening and therefore affords minimal tamper evidence. With this design the contents of the drum may be compromised by an individual with ill intent. The large variability in nominally standard flange curl geometries among different manufacturers exacerbates the problem. The retention boss internal diameter is made to accommodate the largest flange curl dimensions (prevalent e.g. in the U.S.), which means in practice that the overcap will often be a relatively loose fit in other markets (e.g. in Asia, where flange curl dimensions tend to be on the smaller side).

Summary of the invention

The present invention provides a molded plastics overcap for a container closure, the overcap comprising a top wall, a generally annular side wall depending from the top wall, and a retention skirt foldably attached to a rim of the side wall, whereby the retention skirt is foldable between a first position in which it extends from the side wall away from the top wall, to an operative position in which it extends within the side wall towards the top wall; the retention skirt comprising a retention boss which, when the retention skirt is in the operative position, extends radially inward and provides an engagement surface facing the top wall and engageable beneath a closure flange retaining curl to retain the overcap thereon; the retention skirt further comprising a locking projection which projects towards the top wall radially outward of the engagement surface when the retention skirt is in the operative position within the side wall. The overcap may therefore be snapped onto the closure flange retaining curl of a container, with the retention skirt in the operative position. The engagement surface of the overcap's retention boss will then engage beneath the closure flange retaining curl, and the locking projection will project towards the overcap's top wall between the overcap's side wall and the closure flange retaining curl. If an attempt is then made to pry the overcap off the closure flange retaining curl, this will tend to rotate the retention skirt towards its first position extending from the sidewall away from the top wall. However, such rotation is blocked by engagement of the locking projection with the closure flange retaining curl, which lies radially inward of the locking projection. In contrast to the prior art, when the retention skirt is in the operative position, the engagement surface of the overcap's retention boss need not be angled away from the top wall in the radially inward direction, because the retention skirt may be configured to escape mold core tooling when in the first position. This may therefore be adopted as the as-molded position of the retention skirt. The absence of a slope to the retention boss radially inward away from the closure cap top surface when the retention skirt is in the operative position on the other hand means that the overcap will be firmly engageable beneath the closure flange retaining curl, and much more resistant to prying off the container opening. The radial extent of the engagement surface of the overcap's retention boss may also be larger than in the prior art, reducing the problem of loose-fitting overcaps. Because the engagement surface of the overcap's retention boss is thus improved, the cross-sectional areas of the retention boss and/or of the overcap side wall transverse to the hoop direction may be reduced in comparison to the prior art. This not only may lead to significant materials savings (e.g. of the order of 13%), but also may mean that the side wall and/or retention boss are circumferentially "stretchier". Therefore they can be made to a smaller internal diameter that will closely hug and firmly engage "undersized" container flange retaining curls, and yet still can be snap-fitted to "oversized" flange curls with acceptably low press-on forces.
The engagement surface of the retention boss may comprise a hooked profile whereby in the operative position for engagement beneath the closure flange retaining curl, a radially inner portion of the engagement surface is closer to the cap top than a radially outer portion thereof. Then an attempt to pry the overcap off the container opening will tend to draw the retention skirt into tighter engagement in the angle between the closure flange retaining curl and the neck of the container opening. Thus the pry-off attempt will be strongly resisted, making it extremely difficult to remove the overcap without leaving visible damage.
For ease of removal from the mold core, the retention boss when the retention skirt is in its first position may comprise an inwardly-facing surface which tapers relatively gently inward in the direction away from the overcap top wall, is substantially cylindrical, and/or which flares outward in the direction away from the overcap top wall. For example, when the retention skirt is in its first position, the retention boss may comprise a generally frustoconical inwardly-facing surface sloping inward in the direction away from the cap top wall at an angle to a central axis of the overcap of less than 45 degrees, for example at an angle to this central axis of 20-25 degrees, optionally about 23 degrees.
For ease of application of the overcap to the container closure, when the retention skirt is in the operative position, the retention boss may comprise an inwardly-facing surface which tapers relatively gently outward in the direction away from the overcap top wall. For example, when the retention skirt is in the operative position, the retention boss may comprise a generally frustoconical inwardly-facing surface sloping outward away from the overcap top wall at an angle to the central axis of the overcap of less than 30 degrees, for example at an angle to this central axis of 20-25 degrees, optionally about 23 degrees. This may again serve to reduce the required cap press-on force, or keep it to an acceptably low level when adopting a tighter fitting overcap design as regards the variance in nominally standard neck curl diameters present in the marketplace. This measure may be applied together with or independently of a smaller overcap sidewall and/or retaining boss cross-section transverse to the hoop direction, as previously discussed.
The overcap may comprise frangible features which break to allow tamper evident removal of the overcap from the container opening. The improved effectiveness of the retention boss means that higher pull-off forces can be generated before the overcap is unseated from the container closure. This allows the frangible features to be more robust and therefore less prone to accidental damage in the supply chain and hence less prone to giving false positive tamper indications.
The overcap may comprise an outer ring attached to side wall by frangible bridges and a permanent connection. The outer ring may be configured such that it is positionable closely adjacent to a surface of the container (e.g. the upper surface of a flange pocket in a drum head) when the overcap is seated on the container closure. Pry-off tools inserted beneath the overcap side wall are therefore also likely to lever up the outer ring and break one or more of the frangible bridges. When the end user desires to access the container contents for the first time, the frangible bridges can be deliberately broken, whereby the outer ring and permanent connection may then serve as a convenient handle for pulling the overcap off the container closure. The rim of the overcap side wall may be axially recessed within the outer ring, thereby making it less accessible to pry-off tools, without also disturbing the outer ring.
The side wall of the overcap may comprise a frangible line of weakness adjacent to the permanent connection. Pulling on the permanent connection, e.g. using the outer ring after breaking the frangible bridges, may therefore easily and reliably break the line of weakness, making the overcap easier to pull off the container closure. This line of weakness may be substantially absent from the top wall. This allows the closure cap top wall to be substantially homogeneous, allowing for consistent molding, e.g. to provide a consistently substantially flat top surface suitable for the application of printed graphics and text, labels and the like.
A circumferential gusset may be provided between the side wall and top wall to stiffen and strengthen the overcap. The circumferential gusset may be relieved or absent adjacent to the permanent connection so that the side wall is more readily deformable (e.g. outwardly hingeable) to allow removal of the overcap from the container opening by pulling on the permanent connection.
The permanent connection may comprise a pair of generally parallel connecting walls bridging between the outer ring and the side wall of the overcap; the adjacent line of weakness comprising a first part adjacent to one of the connecting walls and a second part adjacent to the other one of the connecting walls. The first and second parts of the line of weakness may be linked by a flexible region at the boundary between the top wall and the side wall of the overcap, whereby the flexible region forms a hinge after the first and second line of weakness have been broken.
The first and second parts of the line of weakness adjacent to the permanent connection may intersect an aperture or frangible region provided at a boundary between the overcap side wall and the retention skirt. This allows the portion of the side wall between the first and second parts of the line of weakness to hinge outwardly about the flexible region after the line of weakness has been broken, making the overcap easier to pull off the container opening.
The retention skirt may similarly comprise a frangible line of weakness. This line of weakness may lie adjacent to the permanent connection where a permanent connection is present; e.g. being breakable to form a break in the circumference of the retention skirt adjacent to the permanent connection. Additionally or alternatively, the retention skirt frangible line of weakness may extend to other parts of the retention skirt, e.g. around the foldable attachment between the retention skirt and the overcap's side wall, so as to disconnect the retention skirt from the remainder of the overcap when broken.
Similarly, a frangible line of weakness in the retention skirt may intersect an aperture or frangible region provided at a boundary between the overcap side wall and the retention skirt. Thus the retention skirt may be more readily deformable to allow removal of the overcap from the container opening by pulling on the permanent connection. For example the frangible line of weakness of the retention skirt may be breakable to form a break in the circumference of the retention skirt adjacent to the permanent connection. Pulling on the permanent connection may therefore also cause such circumferential breakage of the retention skirt.
The retention skirt foldable attachment may comprise a frangible line of weakness and/or alternating circumferentially distributed frangible bridges and gaps. The frangible bridges may for example be formed at the ends of ribs formed on an exterior surface of retention skirt when in the first position, with the gaps being formed at the corresponding ends of the gaps between the ribs.
At least a portion of the retention skirt may thereby be left behind as an intact ring trapped beneath the closure flange retaining curl, to indicate that the remainder of a once-present overcap has been removed from the container closure.
Thus the retention skirt may be substantially circumferentially continuous, with no clearly defined preferential circumferential breaking point. Alternatively, the retention skirt may comprise a line of weakness providing a circumferential breaking point. For example, the retention skirt foldable attachment may comprise a frangible line of weakness and a permanent attachment to the side wall of the overcap; the retention skirt comprising a line of weakness providing a circumferential breaking point.
The invention and some of its optional features and advantages is further explained below with reference to illustrative embodiments shown in the drawings.

Brief description of the drawings

FIG. 1 is a three-quarter perspective view from the top, front and left side of an illustrative overcap embodying the present invention;
FIG. 2 is a top plan view of the overcap of FIG. 1;
FIG. 3 is a bottom plan view of the overcap of the preceding figures, with the retention skirt in the first position, extending from the side wall away from the top wall (i.e. extending toward the viewer, in this bottom plan view);
FIG. 3a is an enlarged view of a portion of FIG. 3;
FIG. 3b is a scrap cross-sectional view on line iiib - iiib in FIG. 3a;
FIG. 4 is a view on arrow iv in FIG. 2 with the retention skirt in the first position;
FIG. 4a is a view on arrow iva in FIG. 2, with the retention skirt in the first position and the outer ring omitted;
FIG. 4b illustrates a variant of FIG. 4a;
FIG. 5 is a view on arrow v in FIG. 2 with the retention skirt in the first position;
FIG. 6 shows a cross-section on line VI-VI in FIG. 2;
FIG. 7 shows a cross-section on line VII-VII in FIG. 3;
FIG. 8 shows a cross-section on line VIII-VIII in FIG. 3;
FIG. 9 is a bottom plan view corresponding to FIG. 3, but shows the retention skirt in the operative position, extending within the side wall towards the top wall (i.e. extending away from the viewer, in this bottom plan view);
FIG. 10 shows a cross-section on line X-X in FIG. 2, with the retention skirt in the operative position;
FIG. 11 is a cross-section corresponding to FIG. 6, but with the retention skirt shown in the operative position;
FIG. 12 shows a cross-section on line XII-XII in FIG. 9;
FIG. 13 is a perspective view from the top and left side of the overcap of the preceding
Figures, shown seated on a container closure;
FIG. 14 is a top plan view of the overcap and container closure of FIG. 13;
FIG. 15 shows a cross-section on line XV-XV in FIG. 14;
FIG. 16 is a bottom plan view corresponding to FIG. 3, showing another illustrative overcap embodying the present invention, with the retention skirt in the first position (i.e. extending toward the viewer);
FIG. 17 is a view corresponding to arrow iv in FIG. 2, showing the overcap of FIG. 16, with the retention skirt in the first position;
FIG. 18 is a view corresponding to arrow v in FIG. 2, showing the overcap of FIGs. 16 and 17, with the retention skirt in the first position;
FIG. 19 is a cross-sectional view of the overcap of FIGs. 16 to 18, on a line corresponding to VI-VI in FIG. 2;
FIG. 20 is a cross-sectional view of the overcap of FIGs. 16-19, on line XX-XX in FIG. 16, with the retention skirt in the first position;
FIG. 21 is a cross-sectional view of the overcap of FIGs. 16-20, on line XXI-XXI in FIG. 16, with the retention skirt in the first position;
FIG. 22 is a bottom plan view corresponding to FIG. 16, but showing the overcap of FIGs. 16-21 with the retention skirt in the operative position, extending within the side wall towards the top wall (i.e. extending away from the viewer);
FIG. 23 is a cross-sectional view of the overcap of FIGs. 16-22, on a line corresponding to VI-VI in FIG. 2, with the retention skirt in the operative position;
FIG. 24 is a cross-sectional view of the overcap of FIGs. 16-23, on line XXIV-XXIV in FIG. 22, with the retention skirt in the operative position;
FIG. 25 is a cross-sectional view of the overcap of FIGs. 16-24, on line XXV-XXV in FIG. 22, with the retention skirt in the operative position;
FIG. 26 is a perspective view of a container closure after fitting and removal of the overcap shown in FIGs. 16-25;
FIG. 27 is an axial cross-section through the container closure after fitting and removal of the overcap shown in FIGs. 16-25;
FIG. 28 is a top perspective view of the retention skirt after separation from the overcap shown in FIGs. 16-25, with the container opening and the remainder of the overcap omitted;
FIG. 29 is a cross-sectional view corresponding to FIG. 27, with the container opening and the remainder of the overcap omitted; and
FIG. 30 is a side view corresponding to FIG. 29.

Detailed description of illustrative embodiments

Figures 1-15 show a first illustrative overcap 10 embodying the present invention. The overcap 10 may be injection molded from a suitable plastics material, such as PCR resin. The overcap 10 comprises a top wall 12, a generally annular side wall 14 (see e.g. FIGs. 4a and 8) depending from the top wall 12, and a retention skirt 16 foldably attached to a rim 18 of the side wall 14. The retention skirt 16 is evertably foldable about its annular line of attachment at the rim 18, between a first position (FIGs. 2-8) in which it extends from the side wall 14 away from the top wall 12, to an operative position (FIGs. 9-15) in which it extends generally co-axially within and next to the side wall 14, towards the top wall 12. The retention skirt 16 may be configured so that in the operative position its outer surface lies closely adjacent to (e.g. in face-to-face contact with) the interior surface of the side wall 14. The retention skirt 16 may therefore be stably circumferentially supported in the operative position by the surrounding side wall 14.
The retention skirt 16 comprises a retention boss 20. When the retention skirt 16 is in the operative position, the retention boss 20 is configured to extend radially inward to provide an engagement surface 22 facing the top wall 12 (see e.g. FIG. 10). In this position, the engagement surface 22 is engageable beneath retaining curl 24 of a container closure flange 26 (FIG. 15), to retain the overcap 10 thereon. The retention skirt 16 further comprises a locking projection 28 which projects towards the top wall 12 radially outward of the engagement surface 22, when the retention skirt 16 is in the operative position within the side wall 14 (FIGs. 9-15).
The overcap 10 may therefore be snapped onto the closure flange retaining curl 24, with the retention skirt 16 in the operative position (FIGs. 13-15). The engagement surface 22 of the overcap's retention boss 20 will then engage beneath the closure flange retaining curl 24, and the locking projection 28 will project towards the overcap's top wall 12 between the overcap's side wall 14 and the closure flange retaining curl 24. If an attempt is then made to pry the overcap 10 off the closure flange retaining curl 24, this will tend to rotate the retention skirt 16 about the rim connection 18, towards the first position (FIGs. 2-8) in which the retention skirt 16 extends from the sidewall 14 away from the top wall 12. However, such rotation is blocked by engagement of the locking projection 28 with the closure flange retaining curl 24, which lies radially inward of the locking projection 28. In contrast to the prior art, when the retention skirt 16 is in the operative position (FIGs. 9-15), the engagement surface 22 of the overcap's retention boss 20 need not be angled away from the top wall 12 in the radially inward direction, because the retention skirt 16 may be configured to escape mold core tooling when in the first position (FIGs. 2-8). Absence of a slope to the retention boss 20 radially inward away from the closure cap top surface 12 when the retention skirt 16 is in the operative position (FIGs. 9-15) on the other hand means that the overcap 10 will be firmly engageable beneath the closure flange retaining curl 24, and much more resistant to prying off the container opening. The radial extent of the engagement surface 22 of the overcap's retention boss 20 may also be larger than in the prior art, reducing the problem of loose-fitting overcaps. Because the engagement surface 22 of the overcap's retention boss 20 is thus improved, the cross-sectional areas of the retention boss 20 and/or of the overcap side wall 14 transverse to the hoop direction (see FIGs. 6-8, 10-12, and 15) may be reduced in comparison to the prior art, providing concomitant advantages in materials usage and technical performance as previously mentioned.
The engagement surface 22 of the retention boss 20 may comprise a hooked profile whereby in the operative position for engagement beneath the closure flange retaining curl 24 (FIGs. 9-13), a radially inner portion 22a of the engagement surface 22 is closer to the cap top 12 than a radially outer portion 22b thereof (see FIG. 10). Then an attempt to pry the overcap 10 off the container opening will tend to draw the retention skirt 16 into tighter engagement in the angle between the closure flange retaining curl 24 and the neck 30 of the container opening. Thus the pry-off attempt will be strongly resisted, making it extremely difficult to remove the overcap 10 without leaving visible damage.
For ease of removal from the mold core, the retention boss 20 when the retention skirt 16 is in its first position (FIGs. 2-9) may comprise an inwardly-facing surface 32 which may taper relatively gently inward in the direction away from the overcap top wall 12 (as shown in FIGs. 6-8), be substantially cylindrical (not shown), and/or flare outward in the direction away from the overcap top wall 12 (not shown). For example, the surface 32 when the retention skirt 16 is in its first position may be a generally frustoconical internal surface sloping inward in the direction away from the cap top wall 12 at an angle to the central axis of the overcap 10 of less than 45 degrees, for example at an angle to this central axis of 20-25 degrees, optionally about 23 degrees. This shallower taper angle of the retention boss 20 allows the retention boss to escape from the undercut in the mold core tool under lower ejection forces than molded plastic overcaps of the prior art, and/or without excess ejection forces while providing a radially broader, and thus more effective, retention boss 20.
For ease of application of the overcap 10 to the container closure, and/or to provide other advantages as previously mentioned, when the retention skirt 16 is in the operative position (FIGs. 9-15), the retention boss 20 may be configured to provide an inwardly-facing surface 34 which tapers relatively gently outward in the direction away from the overcap top wall 12. For example, the internal surface 34 may be generally frustoconical, sloping outward away from the overcap top wall 12 at an angle to the central axis of the overcap 10 of less than 30 degrees, for example at an angle to this central axis of 20-25 degrees, optionally about 23 degrees.
The overcap 10 may comprise frangible features 36, 38a, 38b, 40, which break to allow tamper evident removal of the overcap 10 from the container opening. The improved effectiveness of the retention boss 20 means that higher pull-off forces can be generated before the overcap 10 is unseated from the container closure. This allows the frangible features to be more robust and therefore less prone to suffering accidental damage in the supply chain and hence less prone to providing false positive tamper indications.
The overcap 10 may comprise an outer ring 42 attached to the side wall 14 by frangible bridges 36 and a permanent connection 44a, 44b. The outer ring 42 may be configured such that it can be positioned closely adjacent to a surface 46 of the container (e.g. the upper surface of a flange pocket 48 in a drum head, FIGs. 14 and 15) when the overcap 10 is seated on the container closure (FIGs. 13-15). Pry-off tools inserted beneath the overcap side wall 14 are therefore also likely to lever up the outer ring 42 and break one or more of the frangible bridges 36. When the end user desires to access the container contents for the first time, the frangible bridges 36 can be deliberately broken, whereby the outer ring 42 and permanent connection 44a, 44b may then serve as a convenient handle for pulling the overcap 10 off the container closure. The rim 18 of the overcap side wall 14 may be axially recessed within the outer ring 42 (see e.g. FIG. 10), thereby making it less accessible to pry-off tools, without also disturbing the outer ring 42.
The side wall 14 of the overcap 10 may comprise a frangible line of weakness 38a, 38b adjacent to the permanent connection 44a, 44b. For example, the frangible line of weakness 38a, 38b may comprise one or more membranous webs consisting of a thinner portion of the side wall 14 neighboring the permanent connection 44a, 44b. Pulling on the permanent connection 44a, 44b, e.g. using the outer ring 42 after breaking the frangible bridges 36, may therefore easily and reliably break the line of weakness 38a, 38b, making the overcap 10 easier to pull off the container closure. This line of weakness may be substantially absent from the top wall 12. This allows the closure cap top wall 12 to be substantially homogeneous, allowing for consistent molding, e.g. to provide a consistently substantially flat top surface suitable for the application of printed graphics and text, labels and the like.
The retention skirt 16 may similarly comprise a frangible line of weakness 40. For example a groove may be molded into the radial thickness of the retention skirt 16 and its retention boss 20 to leave a membranous web comprising the line of weakness 40. This line of weakness 40 may lie circumferentially adjacent to the permanent connection 44a, 44b in the overcap 10, where a permanent connection is present; although the retention skirt line of weakness 40 may extend to other parts of the retention skirt, e.g. around the rim 18 at which the retention skirt 16 is foldably attached to the overcap's side wall 14.
A circumferential gusset 50 may be provided between the side wall 14 and top wall 12 to stiffen and strengthen the overcap 10. The circumferential gusset 50 may be relieved or absent at a region 52 adjacent to the permanent connection 44a, 44b. This makes the side wall 14 more readily deformable (e.g. outwardly hingeable) to allow removal of the overcap 10 from the container opening by pulling on the permanent connection 44a, 44b.
The permanent connection may comprise a pair of generally parallel connecting walls 44a, 44b bridging between the outer ring 42 and the side wall 14 of the overcap 10; the adjacent line of weakness in the side wall 14 comprising a first part 38a adjacent to the connecting wall 44a and a second part 38b adjacent to the other connecting wall 44b. The first and second parts 38a, 38b of the line of weakness adjacent to the permanent connection may be linked by a flexible region 52 at the boundary between the top wall and the side wall of the overcap, whereby the flexible region 52 forms a hinge after the first and second line of weakness have been broken. For this purpose the first and second parts 38a, 38b of the line of weakness may extend partially into the thickness of the top wall 12 at its boundary with the side wall 14 (see extension region 38a' of line of weakness first part 38a in FIGs. 7 and 3a; line of weakness 38b having a similar extension region). Additionally or alternatively, the flexible region 52 at the boundary between the top wall 12 and the side wall 14 of the overcap 10 between the first and second parts 38a, 38b of the line of weakness may comprise a thinner part of that boundary, e.g. formed by omitting a circumferential gusset 50 at that part of the boundary, as described above.
The first and second parts 38a, 38b of the line of weakness adjacent to the permanent connection 44a, 44b may intersect an aperture or frangible region 56 provided at a boundary 18 between the overcap side wall 14 and the retention skirt 16 (see e.g. FIGs. 3b, 4a and 10). This allows the portion of the side wall 14 between the first and second parts 38a, 38b of the line of weakness to hinge outwardly about the flexible region 52 after the line of weakness 38a, 38b has been broken, making the overcap 10 easier to pull off the container opening.
The retention skirt 16 may similarly comprise a frangible line of weakness 40. This line of weakness may lie adjacent to the permanent connection 44a, 44b where a permanent connection is present; e.g. being breakable to form a break in the circumference of the retention skirt 16 adjacent to the permanent connection 44a, 44b. Additionally or alternatively, the retention skirt frangible line of weakness may extend to other parts of the retention skirt 16, e.g. around the foldable attachment 18 between the retention skirt 16 and the overcap's side wall 14, so as to disconnect the retention skirt 16 from the remainder of the overcap 10 when broken.
Similarly, a frangible line of weakness 40 in the retention skirt 16 may intersect an aperture or frangible region 56 provided at a boundary between the overcap side wall 14 and the retention skirt 16. Thus the retention skirt 16 may be more readily deformable to allow removal of the overcap from the container opening by pulling on the permanent connection. For example the frangible line of weakness 40 in the retention skirt 16 may be breakable to form a break in the circumference of the retention skirt 16 adjacent to the permanent connection 44a, 44b. Pulling on the permanent connection 44a, 44b may therefore also cause such circumferential breakage of the retention skirt 16.
The same aperture or frangible region 56 may be intersected by both the side wall frangible line of weakness 38a, 38b and the retention skirt frangible line of weakness 40, as shown in FIGs. 3b, 4a and 10. The retention skirt 16 can therefore flex/hinge away from the overcap side wall 14 as a pair of free ends, when the frangible connections 38a, 38b, and 40 have been broken. Moreover, the permanent connection 44a, 44b may be used to easily break both the side wall frangible line of weakness 38a, 38b and the retention skirt frangible line of weakness 40. This allows ready removal of the overcap 10 from the container opening by pulling on the permanent connection 44a.
The outer ring 42 may be provided with a pull tab 54 e.g. diametrically opposite to the permanent connection 44. To remove the overcap 10 from the container opening, the end user can therefore grasp and pull upwardly on the pull tab 54 to break the frangible bridges 36. The outer ring 42 can then be used as a handle to pull upwardly on and twist the permanent connection 44a, 44b. This can then rupture the membranous webs 38a, 38b and hinge the intervening portion of the side wall 14 upwardly and outwardly about the flexible region 52 (if necessary breaking any frangible connection 56). A continued upward pull on the outer ring 42 imposes tensile hoop stress on the retention skirt 16 which is not relieved in the vicinity of the frangible line of weakness 40 by the (now absent) adjacent portion of the overcap side wall 14. The retention skirt's frangible line of weakness 40 therefore readily breaks, to provide two opposed, flexible, free ends of the retention skirt. The side wall 14 and retention skirt 16 are thus both rendered circumferentially discontinuous, whereby they are each more readily radially expandable and can be easily pulled out from beneath the flange curl 24. In FIG. 4a, the outer ring has been omitted, so that the overcap's side wall 14, frangible line of weakness 38a, 38b, permanent connection 44a, 44b, aperture or frangible region 56, and flexible region 52 may be more clearly seen. The omission is for clarity of illustration only, because ordinarily the outer ring will remain connected to the remainder of the overcap 10 via the permanent connection 44a, 44b. For example, the outer ring 42 may remain connected to the top wall 12 of the overcap 10 via the flexible region 52, after the frangible bridges 36, frangible lines of weakness 38a, 38b and 40 and (where applicable) frangible region 56 have been broken. The overcap may therefore remain as a single piece after removal from the container closure, with no broken-off parts to pollute the environment or container contents, and is conveniently recyclable.
The retention skirt 16's foldable attachment at the side wall rim 18 may comprise a frangible line of weakness 58 and/or alternating circumferentially distributed frangible bridges 62 and gaps 64, as shown in Figs. 16-25. The frangible bridges 62 may for example be formed at the ends of ribs 66 formed on an exterior surface of retention skirt 16 when in the first position (as perhaps best seen in FIGs. 17 and 18). As shown in FIGs. 22-25, when the retention skirt 16 is folded to its operative position in which it extends within the side wall 14 towards the top wall 12, the ribs 66 now lie on the inner surface of the retention skirt 16. From FIGs. 22-25, it can be seen that the gaps 64 may be formed at the corresponding ends of the gaps between the ribs 66.
The frangible line of weakness 58 may therefore be broken by pulling on the permanent connection 44a, 44b in a similar way as described above with reference to the embodiment shown in Figures 3-15. However, in contrast to this preceding embodiment, as shown in FIGs. 26 and 27at least a portion of the retention skirt 16 may thereby be left behind as an intact ring 16a trapped beneath the closure flange retaining curl 24, to indicate that the remainder of a once-present overcap 10 has been removed from the container closure. FIGs. 28-30 similarly show the intact ring 16a separated from the remainder of the overcap 10 by breakage of the circumferential line of weakness 58/frangible bridges 62, but with the container closure omitted. This is for clarity of illustration only, because in practice extraction of the ring 16a from beneath the flange curl 24 without breaking the ring 16a will be very difficult or impossible. As access to the ring 16a is restricted by the flange curl 24 and other adjacent parts of the container closure, such breakage is itself quite difficult, whereby the ring 16a will usually remain present to indicate when the remainder of a once-present overcap 10 has been removed.
Thus, the retention skirt 16 (including the retention boss 20) may be substantially circumferentially continuous, with no clearly defined preferential circumferential breaking point. Alternatively, even in embodiments otherwise generally similar to the one shown in FIGs. 16-30 (or otherwise provided with a frangible line of weakness extending at least partly around the circumference of the foldable attachment between the overcap side wall and the retention skirt), the retention skirt may comprise one or more lines of weakness providing a circumferential breaking point (like the line of weakness 40 in the embodiment shown in FIGs. 2-15). For example, the overcap side wall may comprise a frangible line of weakness (e.g. comprising rupturable webs similar to the rupturable webs 38a and 38b described above) and a permanent attachment to an outer ring 42 (e.g. comprising connecting walls similar to the walls 44a and 44b described above), and the retention skirt 16 may be provided with a line of weakness similar or identical to line of weakness 40.
The circumferential frangible line of weakness 58 may comprise a discontinuity whereby the retention skirt 16 and its retention boss 20 are left attached to the remainder of the overcap 10 when the overcap 10 has been torn off from the container closure. Other variations and modifications are readily possible. For example, in embodiments provided with a frangible line of weakness extending at least partly around the circumference of the foldable attachment between the overcap side wall and the retention skirt, any one or more of the components 38a, 38b, 40, 42, 44a and 44b may be omitted. In such embodiments, the aperture/frangible region 56 of the side wall 14 and retention skirt 16 interconnection may be present adjacent to the permanent connection 44a, 44b, effectively being equivalent to an enlarged one of the gaps 64. The aperture 56 then serves to initiate sequential breakage of the frangible bridges 62 when a breaking force is applied via the permanent connection 44a, 44b.
Further variants of the side wall frangible line of weakness 38a, 38b, permanent connection 44a, 44b and related features will be readily apparent. For example, FIG. 4b shows a variant otherwise similar to FIG. 4a, but in which the two axially and generally radially extending connecting walls 44a, 44b comprising the permanent connection are replaced by a single connecting wall 44 which extends between the overcap's side wall 14 and the outer ring 42 (not shown), generally parallel to the cap top wall 12, positioned between the frangible line of weakness parts 38a, 38b and adjacent to the aperture or frangible region 56. This variant may be used in any of the above-described embodiments, where technically compatible.
In another aspect consistent with the foregoing description, the present invention provides a molded plastics overcap for a container closure, the overcap comprising a top wall, a generally annular side wall depending from the top wall, and a retention skirt foldably attached to a rim of the side wall, whereby the retention skirt is foldable between a first position in which it extends from the side wall away from the top wall, to an operative position in which it extends within the side wall towards the top wall; the retention skirt comprising a retention boss which, when the retention skirt is in the operative position, extends radially inward and is engageable beneath a closure flange retaining curl to retain the overcap thereon; the overcap further comprising an outer ring surrounding the side wall; the outer ring and side wall being frangibly connected to each other around their circumferences; the overcap further comprising a permanent connection extending between the outer ring and the side wall, and a line of weakness comprising a first part extending generally axially of the overcap in the side wall on a first side of the permanent connection and a second part extending generally axially of the overcap in the side wall on a side of the permanent connection opposite to the first part; wherein the first and second parts of the frangible line of weakness are interconnected with each other by an aperture and/or by a third part of the frangible line of weakness provided at or proximate to the rim of the side wall. Thus, after breaking the circumferential frangible connection between the outer ring and side wall, the outer ring may be used as a handle to pull on the permanent connection, thereby breaking the frangible line of weakness and further detaching from the retention skirt that portion of the side wall which is adjacent to the permanent connection. The corresponding portion of the retention skirt is therefore no longer reinforced by the side wall (or such reinforcement is significantly reduced) and can be broken or deformed by a continued or further pull on the permanent connection via the outer ring. Thus, the overcap is at least partially freed for removal from the container closure.
The outer ring and its spatial relationship to the other parts of the overcap, including the sidewall may be as described in more detail above, or may be of any other suitable form.
The portion of the side wall between the permanent connection and the cap top wall may remain intact, so that the outer ring remains connected to the remainder of the overcap via the permanent connection. This portion of the side wall and/or a boundary between this portion and the top wall may be made more flexible, e.g. by being made thinner and/or by a discontinuity in a circumferential gusset provided between the side wall and top wall to stiffen and strengthen the overcap, as described in more detail above. After breaking the frangible line of weakness, the portion of the side wall inside the break and still attached to the permanent connection can therefore hinge outward and upward as the outer ring is pulled upward. The retention skirt may comprise frangible lines of weakness as described above, or of any other suitable form. The permanent connection may be as described in more detail above, or of any other suitable form.

Claims

A molded plastics overcap (10) for a container closure, the overcap (10) comprising a top wall (12), a generally annular side wall (14) depending from the top wall (12), and a retention skirt (16) foldably attached to a rim (18) of the side wall (14), whereby the retention skirt (16) is foldable between a first position in which it extends from the side wall (14) away from the top wall (12), to an operative position in which it extends within the side wall (14) towards the top wall (12); the retention skirt (16) comprising a retention boss (20) which, when the retention skirt (16) is in the operative position, extends radially inward and provides an engagement surface (22) facing the top wall (12) and engageable beneath a closure flange (26) retaining curl (24) to retain the overcap (10) thereon; the retention skirt (16) further comprising a locking projection (28) which projects towards the top wall (12) radially outward of the engagement surface (22) when the retention skirt (16) is in the operative position within the side wall (14).
An overcap (10) as claimed in claim 1 wherein when the retention skirt (16) is in the operative position, the engagement surface (22) is not angled away from the top wall (12) in the radially inward direction, or wherein the engagement surface (22) comprises a hooked profile whereby in the operative position of the retention skirt a radially inner portion (22a) of the engagement surface (22) is closer to the cap top than a radially outer portion (22b) thereof.
An overcap (10) as claimed in claim 1 or 2 wherein the retention boss (20) when the retention skirt (16) is in its first position comprises an inwardly-facing surface (32) which tapers relatively gently inward in the direction away from the overcap top wall (12), is substantially cylindrical, and/or which flares outward in the direction away from the overcap top wall (12), the inwardly-facing surface (32) optionally comprising a generally frustoconical internal surface (32) sloping inward in the direction away from the cap top wall (12) at an angle to a central axis of the overcap (10) of less than 45 degrees, optionally of 20-25 degrees, optionally of about 23 degrees.
An overcap (10) as claimed in any preceding claim wherein, when the retention skirt (16) is in the operative position, the retention boss (20) comprises an inwardly-facing surface (34) which tapers gently outward in the direction away from the overcap top wall (12), the inwardly facing surface (34) optionally being generally frustoconical and sloping outward away from the overcap top wall (12) at an angle to the central axis of the overcap (10) of less than 30 degrees, optionally of 20-25 degrees, optionally of about 20 degrees.
An overcap (10) as claimed in any preceding claim and comprising frangible features (36, 38a, 38b, 40) which break to allow tamper evident removal of the overcap (10) from the container opening.
An overcap (10) as claimed in any preceding claim and comprising an outer ring (42) attached to the side wall (14) by a frangible bridge (36) and a permanent connection (44a, 44b), wherein the outer ring (42) optionally is configured such that it is positionable closely adjacent to a surface (46) of the container when the overcap is seated on the container closure, and wherein the rim (18) of the overcap side wall (14) optionally is axially recessed within the outer ring (42).
An overcap (10) as claimed in claim 6, comprising a frangible line of weakness (38a, 38b) adjacent to the permanent connection (44a, 44b), wherein the line of weakness (38a, 38b) adjacent to the permanent connection (44a, 44b) optionally is substantially absent from the top wall (12).
An overcap (10) as claimed in claim 7, wherein a circumferential gusset (50) is provided between the side wall (14) and the top wall (16).
An overcap (10) as claimed in claim 8, comprising an outer ring (42) attached to the side wall (14) by a frangible bridge (36) and a permanent connection (44a, 44b) and wherein the circumferential gusset (50) is relieved or absent adjacent to the permanent connection (44a, 44b).
An overcap (10) as claimed in claim 9 wherein the permanent connection comprises a pair of generally parallel connecting walls (44a, 44b) bridging between the outer ring (42) and the side wall (14) of the overcap (10); the adjacent line of weakness comprising a first part (38a) adjacent to one of the connecting walls (44a) and a second part (38b) adjacent to the other one of the connecting walls (44b).
An overcap (10) as claimed in claim 9 or 10 wherein the first and second parts (38a, 38b) of the adjacent line of weakness are linked by a flexible region (52) at the boundary between the top wall (12) and the side wall (14) of the overcap (10).
An overcap (10) as claimed in claim 11 wherein the first and second parts (38a, 38b) of the line of weakness adjacent to the permanent connection (44a, 44b) intersect an aperture or frangible region (56) provided at a boundary (18) between the overcap side wall (14) and the retention skirt (16).
An overcap (10) as claimed in any preceding claim wherein the retention skirt (16) comprises a frangible line of weakness (40), the overcap (10) optionally comprising an outer ring (42) attached to the side wall (14) by a frangible bridge (36) and a permanent connection (44a, 44b) and the frangible line of weakness (40) of the retention skirt (16) lies adjacent to the permanent connection (44a, 44b), optionally wherein the frangible line of weakness (40) of the retention skirt (16) extends around the foldable attachment (18) between the retention skirt (16) and the side wall (14) of the overcap (10), optionally wherein the frangible line of weakness (40) of the retention skirt (16) intersects an aperture or frangible region (56) provided at a boundary (18) between the overcap side wall (14) and the retention skirt (16), optionally wherein the frangible line of weakness (40) of the retention skirt (16) is breakable to form a break in the circumference of the retention skirt (16) adjacent to the permanent connection (44a, 44b).
An overcap (10) as claimed in any preceding claim wherein the retention skirt (16) foldable attachment comprises a frangible line of weakness (18) and/or alternating circumferentially distributed frangible bridges (62) and gaps (64), optionally wherein the frangible bridges (62) are formed at the ends of ribs (66) formed on an exterior surface of retention skirt (16) when in the first position, with the gaps (64) being formed at the corresponding ends of gaps between the ribs (66).
An overcap (10) as claimed in any preceding claim and configured such that upon removal of the overcap (10) from a seated position on the container closure, at least a portion (16a) of the retention skirt (16) is left trapped on the container closure, optionally wherein the retention skirt (16) is substantially circumferentially continuous, with no clearly defined preferential circumferential breaking point.