GB2312207A - Cap and plug closure assembly - Google Patents

Abstract

A two-piece plastics closure assembly for a container comprises a cap 31 (having an annular depending skirt 33 with retention means 35 on its inner surface for engagement with complementary means 12 on the container neck 11) and a plug 50. The cap 31 has means 40 for holding the plug 50 against the cap underside 32 prior to fitting the whole assembly to a container. Optionally these means 40 comprise a series of radially-inwardly directed fins engaging the outer periphery of the plug 50, being formed on the inner surface of the skirt 33 between the cap underside 32 and the retention means 35. The plug 50 includes a spigot portion 54 adapted to have an interferance fit in the container mouth 10.

Description

PLUG CLOSURE ASSEMBLY The present invention relates to a closure for a bottle, tube or like container and, in particular, to a snap-off closure having an associated plug insert adapted to be retained in the container aperture after the closure has been applied to the container for the first time.

A closure of this type is known from British Patent No. 2 255 083 in which the plug is retained loosely between the closure underside and a retaining bead formed on the inner circumference of the closure skirt. The retaining bead is a dual-function feature which also serves to retain the closure on the container neck by engagement behind a nose formation provided on the neck finish.

When such a closure is applied to a container for the first time, the plug is displaced away from the retaining bead by engagement with the container mouth until the plug comes into contact with the underside of the closure.

Then it is forced into the container mouth where it is held by interference. This arrangement allows the closure and plug to be offered to the container as a unitary assembly in the packaging plant and simplifies the packaging process.

The looseness of the plug behind the retaining bead allows a degree of self-centring to assist delivery of the plug into the container mouth. However, one of the drawbacks of such looseness is that plugs occasionally become separated from their respective closures. In such circumstances, a closure may be assembled to a container in the packaging plant with no plug present. On a packaging line which is designed to assemble closure, plug and container in a single operation, the omission of the plug is very difficult to detect through routine quality control. Also, the plug may become diagonally oriented within the closure to such a degree that its insertion into the container mouth is hindered.

It is therefore an object of the present invention to overcome these problems by providing a closure and plug assembly in which the plug is firmly retained against the underside of the closure until it is delivered into a container mouth during the packaging process. It is a further object of the invention to provide a closure and plug assembly which allows self-centring of the plug during the step of attaching the closure and plug assembly to a container for the first time.

The invention is a two-piece plastics closure comprising a cap portion having an annular skirt depending therefrom said skirt being provided with retention means on its radially inner surface for engagement, in use, with complementary retention means formed on a container neck, and a plug element including an insert portion having a predetermined outer diameter adapted to be an interference fit in said container mouth, said cap portion having means for holding said plug element against the underside of said cap portion prior to the fitting of said closure to a container.

In a particularly preferred arrangement, the means for holding the plug element in position against the underside of the cap portion comprises a series of radially-inwardly directed fins formed on the inside surface of the annular skirt between the retention means and the cap portion underside. The fins are dimensioned to engage the outer periphery of the plug element and hold it in place. Preferably, at least three fins are provided around the inner periphery of the annular skirt. For best results, the fins are substantially equally spaced around the annular skirt. Preferably, the fins extend the full distance between the retention means and the cap portion underside. The thickness of the fins is selected to ensure that they become flattened by engagement with a container neck in use in such a way that they do not interfere with the final fitting and sealing performance of the closure on the container neck. The fins may be slightly swept in the clockwise or anti-clockwise sense to assist in this flattening step. The inherent flexibility of the fins allows the plug a degree of transverse movement relative to the cap portion underside against their resilience, so that the plug element can centre itself when the closure is installed on a container neck for the first time.

Preferably, the fins are formed with a radially inward taper extending from an upper portion adjacent the cap portion underside radially inwardly towards a lower portion in the vicinity of the retaining means. This taper assists in urging the plug element into abutment against the cap portion underside.

Alternatively, the plug element may be retained against the cap portion underside by a spigot and aperture arrangement, the most preferred arrangement being spigot means formed on the underside of the cap portion engaging in an aperture or apertures in the plug element. The aperture or apertures may serve as sprinkling holes for dispensing dry goods such as herbs and spices or as pouring holes for a liquid such as an edible oil.

The plug element may be provided with flange means adapted to sit on the rim of a container mouth, in use. Also, the plug element may have a slight inward taper at its lower extremity to assist the initial guidance of the plug element into the container mouth.

In an especially preferred arrangement, the closure is provided with tamper-evident means on the lower periphery of the skirt portion. This may be in the form of a guaranty strip which is removable by the purchaser of the package when the container is opened for the first time. The guaranty strip may have a finger grip portion which makes it easier for the purchaser to grasp the guaranty strip to effect its removal.

In screw-on/screw-off and push-on/ screw-off closures, the guaranty strip conveniently extends around the entire circumference of the lower periphery of the skirt portion. Removal of the guaranty strip then separates the closure skirt portion from a ring which may be retained on the container neck when the closure in unscrewed. Alternatively, for snap-on/pull-off closures, the guaranty strip may extend circumferentially around the closure skirt lower periphery except for a relatively short arc. On removal of the guaranty strip, which is designed to rupture at the site of this short arc, the closure forms a lid portion hinged to an anchoring band that remains on the container neck.

This arrangement enables the closure to be pulled open, hinged away from the container mouth and then snapped back into position after dispensing part of the container contents. The lid portion of the closure may be provided with a thumb tab diametrically opposite the hinge to assist in lifting the lid from the container mouth.

The invention will now be described by way of example only with reference to the drawings in which: Figure 1 is a cross-sectional view through part of a closure and plug assembly according to the present invention shown in place on a container neck; Figure 2 is a similar view to Figure 1 showing a cross-section through part of a closure and plug assembly according to the present invention prior to placement on a container neck; Figure 3 is a perspective view of the underside of a closure in accordance with the present invention; Figure 4 is a detail view of part of Figure 1; Figure 5 is a sectional view on line 3-3' of Figure 2, and Figure 6 is a detail view of part of Figure 5.

Referring now to Figure 1, there is shown in sectional view the left hand side of a glass container neck 11 which surrounds a container mouth 10. The container mouth 10 has a relatively smooth bore and formed on the outside of the neck 11 are circumferential beads 12 and 13, the purpose of which will be described in more detail below. The rim 14 of the neck 11 is relatively flat with gently radiused edges typical of glass neck finishes.

A flange member 52 of a plug 50 rests on top of the rim 14 of the container neck 11. The plug 50 is formed of a pliable plastics material approved for use in foodstuffs packaging, such as polyethylene, and comprises an upper plate element 51 provided with a series of apertures 53 (only one shown) through which dry particulate goods may be sprinkled in use. A spigot portion 54 depends from the plate element 51 and penetrates into the upper part of the container mouth 10. The outer surface of the spigot portion 54 is formed with a series of circumferential interference ribs 55 which ensure good sealing contact between the plug 50 and the container mouth 10. These circumferential interference ribs 55 also serve to concentrate the frictional forces between the plug 50 and the container mouth 10 so that the plug 50 is firmly retained therein during the working life of the closure. The lower extremity of the spigot portion 54 is formed with a slight inward taper 56, shown slightly exaggerated in this view for emphasis. The taper is of assistance during initial placement of the closure and plug assembly on a container mouth 10, when it serves to help in centring of the plug 50 relative to the container mouth 10. In practice, it will be understood by persons skilled in the art that the taper is not so large that it causes hindrance to the dispensing of dry goods. Nor must it provide a large dead volume for liquid contents.

Overlying the plug 50 and surrounding the upper portion of the container neck 11 is a cap 30. The cap comprises a top portion 31, the underside 32 of which abuts the plate element 51 and closes the apertures 53. The top portion 31 has an annular depending skirt 33 which is formed on its radially inner surface with a circumferential bead 35 that is captured, in use, behind the corresponding circumferential bead 12 formed on the container neck 11. At its lower periphery 34, the closure skirt 33 is conjoined to a guaranty strip 37 by a thin web of material which extends virtually around the entire circumference of the cap 30. Similarly, at the lower periphery of the guaranty strip 37, there is an annular anchoring band 38 to which it is conjoined by a further thin web extending virtually around the entire circumference. The anchoring band is formed on its radially inner surface with a retaining bead 39 which is captured, in use, behind retaining bead 13 formed on the outer surface of the container neck 11. In the regions where the respective retaining beads 12, 35 and 13, 39 interengage, this has been depicted in Figure 1 by overlapping the interengaging portions. However, it will be understood by persons skilled in the art that the hard glass material of the container neck 11 causes slight elastic deformation of the softer material of the cap 30 and that the overlapping portions shown are, in practice, elastically deformed.

Between the underside 32 of the cap 30 and the retaining bead 35 formed on the radially inner surface of the cap skirt 33 is a series of gripping fins 40 spaced at substantially equal intervals around the inner circumferential wall of the cap skirt 33.

As best seen with reference to Figure 2, which shows the cap and plug assembly without the inserted container neck 11, these gripping fins 40 extend radially inwardly from the inner circumferential wall of the cap skirt 33. They are formed with a slight radially inward taper from the upper portion 42 near the cap underside 32 towards the lower portion 41 in the vicinity of retaining bead 35. In other words, their radial dimension is slightly greater nearer the lower portion 41. This non-lateral configuration serves to assist in urging the plate element 51 of the plug 50 into engagement with the underside 32 of the cap 30. Figure 2 therefore illustrates how the cap 30 and plug 50 form a unitary assembly prior to placement on a container neck for the first time, with the plug in the most favourable location abutting the cap underside 32.

The gripping fins 40 are very thin in cross-section and are sufficiently resilient that they permit a moderate degree of transverse movement of the plate element 51 relative to the cap underside 32 for self-centring purposes during placement of the cap and plug assembly on a container neck for the first time. Moreover, the gripping fins 40 are sufficiently flexible that they become flattened when installed on a container neck 11 and thereby cause no interference to the sealing performance of the cap.

Figure 3 shows a perspective view of the underside of cap 30 after the guaranty strip 37 has been removed. This view omits the container neck 11 and plug 50 for clarity and illustrates the cap 30 hinged to anchoring band 38 at hinge 37a. Hinge 37a is formed by making the guaranty strip extend around almost the entire circumference of the cap skirt lower periphery 34 and the anchoring band upper periphery, respectively, except for a relatively short arc which remains when the guaranty strip is removed. Three gripping fins 40 are just visible in this view, disposed between the retaining bead 35 formed on the cap skirt 33 and the cap underside 32. A thumb tab 36 is provided diametrically opposite the hinge 37a to assist in lifting the lid from the container mouth.

Figure 4 is an enlarged view of part of the arrangement shown in Figure 1, showing the cap and plug assembly in position on a container neck 11. As in Figure 3, the guaranty strip 37 has been detached from the lower extremity 34 of the closure skirt 33. Figure 4 is included to show more clearly the slight radially inward taper of the gripping fins 40. Here it can be seen quite plainly that the upper portion 42 of gripping fin 40 has a lesser radially inward extent than the lower portion 41 thereof. Although this view shows the gripping fin 40 stopping short of the circumferential bead 35, it is possible for it to extend all the way from the underside 32 of the cap 30 to the bead 35, as mentioned previously. The inherent flexibility of the gripping fins 40 means that such an arrangement does not interfere with the sealing performance of the closure.

Figure 5 is a cross-sectional view taken on line 3-3' looking upwards towards the underside 32 of the cap 30. In this view, six gripping fins are shown projecting radially inwardly from the inner circumferential wall of the closure skirt 33. These are substantially equally spaced around the periphery of the closure interior.

Figure 6 is an enlarged view of a part of Figure 5, showing a preferred geometry for a gripping fin 40. As in previous Figures, the interference between the gripping fin 40 and the periphery of the flange member 52 of the plug 50 is depicted as an overlap. In practice, however, the gripping fin 40 is elastically deformed and its resilience serves to grip the flange member 52 and hold it in abutment against the underside 32 of the cap 30. There may also be a slight plastic deformation of the periphery of the flange member 52, but it has a thickness which is relatively much greater than that of the gripping member 40, so the major deformation is experienced by the gripping member 40.

Although the present invention has been particularly described above with reference to one preferred embodiment, it will be understood by persons skilled in the art that other variants are possible without departing from the scope of the claims which follow.

For example, the retaining means 12, 35 on the container and closure skirt, respectively, may be in the form of screw threads rather than snap-action formations. A guaranty strip and anchoring band (or tamper-evident band) of known design may then be chosen more in keeping with such arrangements adapted for screw-threaded disengagement.

Claims (10)

1. A two-piece plastics closure comprising a cap portion having an annular skirt depending therefrom said skirt being provided with retention means on its radially inner surface for engagement, in use, with complementary retention means formed on a container neck, and a plug element including an insert portion having a predetermined outer diameter adapted to be an interference fit in said container mouth, said cap portion having means for holding said plug element against the underside of said cap portion prior to the fitting of said closure to a container.

2. A closure as claimed in claim 1 wherein said means for holding the plug element in position against the underside of said cap portion comprises a series of radially-inwardly directed fins formed on the inside surface of the annular skirt between the retention means and the cap portion underside, said fins being dimensioned to engage the outer periphery of the plug element.

3. A closure as claimed in claim 2 wherein at least three fins are provided around the inner periphery of the annular skirt.

4. A closure as claimed in claim 2 or claim 3 wherein the fins are substantially equally spaced around the inner periphery of the annular skirt.

5. A closure as claimed in any one of claims 2 to 4 wherein the fins extend the full distance between the retention means and the cap portion underside.

6. A closure as claimed in any one of claims 2 to 5 wherein the fins are formed with a radially inward taper extending from an upper portion adjacent the cap portion underside radially inwardly towards a lower portion in the vicinity of the retaining means, said taper serving to assist in urging the plug element into abutment against the cap portion underside.

7. A closure as claimed in any one of claims 2 to 6 wherein the fins are sufficiently thin and flexible that they become flattened by engagement with a container neck in use and thereby do not interfere with the sealing performance of the closure.

8. A closure as claimed in claim 7 wherein the fins are swept in the clockwise or anti-clockwise sense to facilitate flattening thereof when the closure is installed on a container neck for the first time.

9. A closure as claimed in any one of claims 2 to 8 wherein the flexibility of the fins allows the plug a degree of transverse movement relative to the cap portion underside against their resilience so that the plug element can centre itself when the closure is installed on a container neck for the first time.

10. A two-piece plastics closure substantially as described herein with reference to the drawings.