IE902789A1

IE902789A1 - Safety closure

Info

Publication number: IE902789A1
Application number: IE278990A
Authority: IE
Original assignee: Cmb Foodcan Plc
Priority date: 1989-08-02
Filing date: 1990-08-01
Publication date: 1991-02-27
Also published as: WO1991001924A1; GB8917646D0; ZA906061B

Abstract

A safety closure for a container has a disc-like top (1), a cylindrical skirt (3) downwardly dependent from the periphery thereof, which skirt is threaded to engage a corresponding thread on the neck of the container, and a substantially frusto-conically shaped skirt (5) provided with internal ribs (8, 18) for engagement with corresponding abutments (10) on the container. The frusto-conical skirt is deformable such that the ribs and abutments do not engage when the skirt is deformed, and has a wall thickness which increases gradually from the point (6) at which it merges into the cylindrical skirt to its outer end (7).

Description

SAFETY CLOSURE This invention relates to safety closures and is especially concerned with a safety closure which requires a combined squeezing and turning operation to remove it from a container to which it is applied.

Many different types of safety closure, or child-resistant closure, have been proposed, amongst which is the type generally known as the squeeze-and-turn’* type. This has a threaded skirt for screw-threaded application to and removal from the neck of a container, and a deformable portion including one or more internal fins or lugs which co-operate with corresponding abutments on the container neck to resist the unscrewing operation necessary to remove the closure from the container until the deformable portion of the closure is deformed to place the fins or lugs clear of the abutments. A simple form of this type of safety closure is disclosed in United Kingdom Patent Specification 1521201, in which the closure is provided with a single skirt, the upper portion of the skirt being provided with a screw-thread for engagement with a screw-thread on the container neck; and the lower portion of the skirt being deformable and having internal lugs which engage a camming projection on the container neck. When the closure is screwed fully on to the container neck, the lugs on the closure and the camming projection are in engagement and simple unscrewing removal of the closure is impossible. Removal of the closure can only be accomplished if the lugs are placed clear of the projections, and this is accomplished by deforming the lover part of the skirt of the closure by radial pressure applied at right angles to the position of the lugs and projections.

A double-skirted or double-walled variation of this type of safety closure is disclosed in United Kingdom Patent Specification No: 1387572. This shows a closure having an inner skirt, which is provided with a screw-thread for engagement with a screw-threaded container neck, and an outer skirt, which is deformable and has projections engaging with complementary recesses on the container neck. Other closures of this general type are disclosed for example in UK Patent Specifications Nos: 1434546, 1603294 and 2011869.

Both the single-walled and the double-walled safety closure are very efficient, but they do have disadvantages. Thus, in the single-walled safety closure, one part of the closure skirt, the threaded part, must of necessity be substantially non-deformable, whereas the other part of the skirt must be deformable in order that the lugs and projections may be taken out of engagement. This is not a problem with the double-walled closure, since the threaded part may be non-deformable, and the radially outer wall deformable to the extent necessary to remove the lugs from engagement with the projections. However, by its very nature the double-walled closure is unattractive. The presence of the outer wall or skirt, necessarily separated from the inner wall, gives to the closure an overall '’heavy'· or clumsy appearance.

It is the object of the present invention to provide a safety closure of the general type described above, which does not suffer from the disadvantages of the singlewalled closure but yet has a more attractive and pleasing appearance than the known double-walled closures.

According to the invention there is provided a safety closure for a container, said closure having a disc-like top, a cylindrical skirt downwardly dependent from the periphery thereof, which skirt is threaded to engage a corresponding thread on the neck of the container, and a substantially frusto-conical shaped skirt provided with internal ribs for engagement with corresponding abutments on the container, the frusto-conical skirt being deformable such that said ribs and abutments do not engage when said skirt is deformed, wherein the frusto-conical skirt has a wall thickness which increases gradually from the point at which it merges with the cylindrical skirt to its free end.

A structure of this kind has the advantage of an attractive appearance, such as that of the known singlewalled closure, combined with the ease of manufacture of the known double-walled closure.

In a preferred embodiment the frusto-conical skirt merges at its upper end into the cylindrical skirt at a position below the periphery of the disc-like top.

The thickness of the wall of the frusto-conical skirt where it merges with the cylindrical skirt may for example be of the order of 0.3 to 0.5 mms, and the thickness of its free end for example 1.0 to 2.0 mms; this represents a taper of some 2° to 5° for a 24mm cap. The cone angle between the frusto-conical skirt and the screw threaded cylindrical skirt is preferably of the order of 5° to 15®, for example 8®.

In one embodiment of the invention the internal ribs on the frusto-conical skirt are radial ribs; alternatively they may lie at an angle to the radius of the cap. In the latter case the abutments on the container may be shaped, e.g. concavely, to receive the leading edges of the ribs.

The thread on the container is suitably provided with a stop buttress to prevent overtightening of the closure onto the container, and also to assist alignment of the closure and container. Alternatively, for the same purpose, the lowermost turn of the thread on the closure may be enlarged, e.g. by enlarging the root internal diameter at this point whilst keeping the thread peak diameter constant, and the thread peak diameter on the container enlarged.

Additional safety may be built into the closure by providing it with a tear-off strip or tear band at the lower end of the frusto-conical skirt, such that the deformable skirt cannot be deformed until after the tear band has been removed. Thus, to remove the closure it is first necessary to remove the tear band, then squeeze the deformable skirt to place the ribs and abutments clear of each other, and finally unscrew the closure. The tear band will suitably be joined to the deformable skirt by spaced frangible bridges. In one form the bridges will be positioned axially below the squeeze points of the skirt, with the internal surface of the tear band being tight up against the cylindrical surface of an annular shoulder formed on the container below the abutments. Squeezing of the skirt to deform it is impossible until the tear band has been removed.

In a second form the internal surface of the tear band is provided with a series of spaced axial ribs, the radially inward surfaces of the ribs being tight up against the annular shoulder on the container to prevent deformation of the skirt on squeezing until after removal of the tear band. The axial ribs may be joined by an annular web for additional stability.

In another form of the closure the internal surface of the tear band is provided with inwardly and obliquely directed teeth or ratchets which mesh with corresponding teeth or ratchets formed on an annular shoulder on the container. In this case, even if it is possible to deform the skirt by squeezing, it is not possible to unscrew the closure until after the tear band has been removed.

In those embodiments of the invention in which the lower end of the frusto-conical skirt is provided with a tear band it may be of advantage to provide yet further •’safety'’ by the provision of an upstanding annular collar which surrounds the lower portion of the frusto-conical skirt and prevents access to the squeeze points on the skirt. The annular collar may be formed as an extension of the tear band and may, if desired, be stiffened at least in the region of the squeeze points by buttresses or stiffening ribs. The stiffening ribs on the collar may suitably be formed as extensions of the axial ribs provided on the inside of the tear band in accordance with the embodiment detailed above.

In a still further embodiment of the invention, a security ring is provided at the lower end of the frustoconical skirt, and joined thereto by a frangible web or spaced frangible bridges. The inner wall or surface of the security ring is provided with one or more inwardlydirected projections which act against a surface of the container such that when the closure is unscrewed from the container the web or bridges fracture and the security ring remains on the container. The inwardly-directed projections are preferably upwardly-directed spaced arcuate fins which, on unscrewing of the closure, come into contact with an annular shoulder on the container and prevent further upwards movement of the security ring relative to the container neck. In such an embodiment as this, the security ring is preferably attached to the frusto-conical skirt by means of four equi-spaced frangible bridges, suitably positioned at the nodal points of the cap skirt (i.e. those points which do not move out of position when the frusto-conical skirt is deformed).

The upwardly- and inwardly-directed fins are preferably four in number, and situated between adjacent pairs of bridges.

The fins may be moulded in the closure in the attitude which they assume when the closure is attached to the container. Alternatively they may be moulded as inwardlyand downwardly-projecting fins which are then caused to flex and pivot about their junction with the security ring in a post-moulding operation so that they assume an inwardly- and upwardly-directed attitude. This postmoulding operation can be performed as the closure is screwed onto the container.

The accompanying drawings illustrate a number of possible forms of safety closure according to the invention. In the drawings, Figure 1 is a part sectional elevation of a safety closure according to one embodiment; Figure 2 is a detail of a second embodiment, having a tear band, attached to a container;.

Figure 3 is an elevation, partly in section, of a further embodiment having an alternative form of tear band; Figure 4 is a section on the line IV-IV of Figure 3; Figure 5 is a part sectional elevation of a fourth embodiment of the invention; Figure 6 is a section on the line VI-VI of Figure 5; Figure 7 is a part sectional elevation of a fifth embodiment of the invention; and Figure 8 is a part-sectional elevation of a sixth embodiment of the invention.

The safety closure shown in Figure 1 has a disc-like top 1 from which depends an internal flexible annular sealing plug 2. From the periphery of the disc-like top l depends a substantially rigid cylindrical inner wall 3 having a screw thread 4 for engagement with a complementary thread on the neck of a container to which the closure is applied.

A frusto-conical outer wall 5 merges into the cylindrical wall 3 a short distance below the top of the wall 3. The wall 5 tapers in thickness, its thinnest portion being at the point 6 where it merges into the cylindrical wall 3, and its thickest portion being at its outer end 7. The thinning of the wall 5 where it merges into the wall 3 gives the necessary flexibility or deformability to the wall 5.

Formed internally of the wall 5 are ribs 8 which engage and co-operate with corresponding abutments or projections on the container neck in the manner disclosed in the prior Specifications referred to above. Thus, as the closure is screwed onto the container neck, the ribs 8 ride over and seat behind the corresponding abutments on the neck, so that normal unscrewing removal of the closure is impossible. In order to unscrew the closure, the ribs 8 must be placed clear of the abutments, and this is achieved by exerting radial pressure on the wall 5, at the positions of diametrically opposed flats 9 provided at right angles to the ribs 8, and this has the effect of deforming the wall 5, at its lower end, into elliptical form whereby the ribs 8 are placed clear of the abutments on the container neck and the closure may then be unscrewed in the normal manner.

In the embodiment shown in Figure 2, the internal ribs on the frusto-conical skirt 5 are not radial (as at 8 in Figure 1) but are rather obliquely directed ribs 18 which bear against abutments 10 formed on the neck portion 11 of a container. There are suitably two such abutments 10, diametrically opposed. Situated beneath abutments 10 is an annular shoulder 12 having a cylindrical outer surface 13. Attached to the end of skirt 5 is a tear band 14.

The attachment of band 14 to skirt 5 is through spaced frangible bridges 15. Preferably there is a bridge adjacent each squeeze point or flat 9.

The inner surface of the band 14 is a tight, or at least snug, fit against the cylindrical surface 13 of the annular shoulder 12. Thus, it is impossible to squeeze the skirt 5 at the squeeze points 9 while the tear band 14 is attached to the skirt 5. Removal of the tear band must precede the deformation and subsequent unscrewing of the closure.

In the embodiment of Figures 3 and 4 the internal ribs 18 are again obliquely directed, as in the Figure 2 embodiment. The abutments 10 on the container (one only is shown) are profiled to receive the edges of the ribs 18. Beneath the abutments 10 is an annular shoulder 20 provided with opposed sets of ratchets 21.

Attached to the lower end of skirt 5 is a tear band 24, the attachment of the tear band to the skirt being through spaced frangible bridges 25. Provided internally of the tear band are opposed series of ratchets 26 which mesh as shown with the ratchets 21 on the container neck, thus preventing unscrewing of the closure until the tear band 24 has been removed. The ends of the tear band are joined by a thin link band 27 through a frangible bridge 28.

The closures of Figure 2 and Figures 3 and 4 are applied to a container by simply screwing them on in the normal way. As the closures approach their fullytightened position, the ribs 18 ride over the abutments 10, and in the case of the Figures 3 and 4 embodiment the ratchets 26 on band 24 ride over the ratchets 21. Normal unscrewing of the closures is then impossible, since abutment of ribs 18 and ratchets 26 with abutments 10 and ratchets 21 respectively prevent unscrewing rotation of &°ι δ the closures. Further, in neither case can the skirts 5 be squeezed to deform them so as to place the abutting features clear of each other.

Indeed, the application of pressure at squeeze points 9 only serves to increase the engagement of the ratchets in the Figures 3 and 4 embodiment. The tear bands 14, 24 must be removed before the skirts 5 can be deformed and the closures removed from their respective containers.

The embodiment of Figures 5 and 6 and that of Figure 7 are similar to that shown in Figure 2. In the former cases, however, the tear band 14 is radially spaced from the external cylindrical surface of the shoulder 12, but is provided with spaced axial ribs 30 in the region of the squeeze points 9 (only one set is shown, for convenience). The tear band is attached to the skirt 5 by bridges 31 adjacent the ribs 30 and by spaced bridges 32 elsewhere. The interior axial surfaces of the ribs 30 are a tight, or at least snug, fit against the external cylindrical face of the shoulder 12. The provision of an integrally-formed arcuate web 33, at least in the region of the ribs 30, helps to ensure that when the closure is squeezed at diametrically-opposed points 9, the abutment of the ribs 30 against the shoulder 12 prevents the skirt 5 from being deformed.

In the form of the invention illustrated in Figure 7, which is otherwise identical to that of Figures 5 and 6, a further safety feature is provided by the upstanding annular collar 40 which surrounds the lower half of skirt 5 and prevents finger access to the squeeze points 9. The collar 40 is an axial extension of tear band 14 and, in the embodiment shown, is provided with internal strengthening ribs 41 which conveniently are axially aligned with ribs 30.

The example of the invention illustrated in Figure 8 is similar in many respects to that shown in Figure 5, but in the case of the Figure 8 example a security ring 50 is attached to the lower end of skirt 5 by means of four equi-spaced frangible bridges 51, the points of attachment ^0^789 of the bridges 51 to skirt 5 being at the nodal points of the skirt. Integrally moulded to the security ring 50 are four arc-shaped flexible fins 52, equi-spaced around the ring 50 and situated between respective pairs of bridges 51 when the ring 50 is viewed in plan. Fins 52 have their roots at the lower end of ring 50, from where they extend upwardly and inwardly. An annular shoulder 53 is provided on the container beneath the screw-threaded neck 11.

The closure is removed by squeezing the skirt 5 at the squeeze points 9, whereby the ribs 18 are placed radially clear of the abutments 10. The closure may then be unscrewed until the free ends of the fins 52 come into contact with the lower face of the shoulder 53. This arrests the upwards movement of security ring 50.

Continued unscrewing of the closure stresses the bridges 51 until they break, allowing complete removal of the closure while the ring 50 remains on the container.

The diameter of the circle produced by the upper ends of the fins 52 is preferably slightly larger, e.g. by about 2 mms, than the external diameter of the nearest portion 54 of the container, so ensuring that the ring 50 falls down the container and is not retained in its Figure 8 position by frictional engagement with the container.

All the closures illustrated are suitably produced by the injection moulding of a thermoplastics material such as, for example, polypropylene or polystyrene.

Claims

1. A safety closure for a container, said closure having a disc-like top (1) , a cylindrical skirt (3) downwardly dependent from the periphery thereof, which skirt is threaded to engage a corresponding thread on the neck of the container, and a substantially frustoconically shaped skirt (5) provided with internal ribs (8,18) for engagement with corresponding abutments (10) on the container, the frusto-conical skirt being deformable such that said ribs and abutments do not engage when said skirt is deformed, wherein the frusto-conical skirt has a wall thickness which increases gradually from the point (6) at which it merges into the cylindrical skirt to its outer end (7).

2. A safety closure according to claim 1 wherein the frusto-conical skirt merges at its upper end into the cylindrical skirt at a position below the periphery of the disc-like top.

3. A safety closure as claimed in claim 1 or 2 in which a tear band (14,24) is provided at the lower end of the frusto-conical skirt (5), removal of the tear band being necessary before the skirt can be deformed.

4. A safety closure as claimed in claim 3 wherein the inside surface of the tear band comprises a series of spaced axial ribs (30) the radially inward surfaces of which are a tight fit against an annular shoulder (12) on the container.

5. A safety closure as claimed in claim 4 wherein the axial ribs are connected by an arcuate membrane.

6. A safety closure as claimed in claim 3 wherein the internal surface of the tear band is provided with inwardly and obliquely directed teeth or ratchets (26) which mesh with corresponding teeth or ratchets (21) formed on an annular shoulder on the container.

7. A safety closure as claimed in any of claims 1 to 6 wherein the lower portion of the frusto-conical skirt is surrounded by an annular collar (40).

8. A safety closure as claimed in claim 7 wherein the Ί05~76°» annular collar is an axial extension of the tear band of any of claims 3 to 6.

9. A safety closure as claimed in claim 1 or 2 wherein a security ring (50) is provided at the lower end of the frusto-conical skirt (5), and joined thereto by a frangible web or spaced frangible bridges (51), the inner wall of the security ring being provided with one or more inwardly-directed projections (52) which act against a surface of the container such that when the closure is unscrewed from the container the web or bridges (51) fracture and the security ring (50) remains on the container.

10. A safety closure as claimed in claim 9 wherein the inwardly-directed projections are upwardly- and inwardlydirected spaced fins (52) which act against an annular shoulder on the container.

11. A safety closure according to any preceding claim, substantially as hereinbefore described with rererence to and as illustrated in the accompanying drawings.