GB2025381A - Container and closure assemblies - Google Patents

Abstract

A plastics container (10), see in plan Fig. 2, for a particulate product such as cocoa has an outwardly projecting flange (15) formed around its mouth for providing the container (10) with a plane upper surface suitable for attachment of a diaphragm closure, the flange (15) being of constant thickness and provided with four regular and regularly spaced lobes (17) where the flange (15) is of increased radial depth. In use of the container these lobes (17) serve individually to engage four formations (25), Fig. 3, forming a multi-start screw thread on a screw closure (21), so as to retain the closure (21) in position on the container (10). <IMAGE>

Description

SPECIFICATION Containers and screw closures therefor This invention relates to containers and to screw closures on or for such containers.

For the packaging of brown powders (e.g.

drinking chocolate and cocoa) and other particulate food products there exists a need for a plastics container which has a plane upper surface of sufficient area to provide an hermetic seal with a plane and rupturable or removable diaphragm heat-sealed or otherwise adhered in position, and which furthermore is capable of accepting a screw closure to provide protection for the diaphragm closure to the point of use and to provide a reclosure for the container when the diaphragm closure has been ruptured or removed.

It is known to provide such a plane upper surface on a flange which projects outwardly from integral connection with the container side wall around the container mouth. It is also known to provide a container side wall with exterior screwthread formations for engagement with complementary screw-thread formations on the interior of a tubular skirt of a screw closure. In this respect it will be noted that "side wall" is used in a general sense and would include, for example, the reduced-diameter neck of a blow-moulded plastics bottle.

The provision of an outwardly projecting flange suitable for attachment of a diaphragm closure as described above introduces difficulties in arranging the container for screw-thread engagement by a screw closure overlying the diaphragm. Suitable screw-thread formations can be provided on the container side wall beneath the flange, but they must be carried so as to stand proud of the flange radially of the closure in order to provide the necessary clearance required for the complementary screw-thread formations on the closure skirt to pass the flange when the closure is applied. Such a screw-thread arrangement represents increased costs in material and production, and furthermore tends to result in a container lacking aesthetic appeal.

The present invention seeks to provide a plastics container having a peripheral flange suitable for attachment of a plane diaphragm closure and with provision for receiving a screw closure, and yet which lacks, wholly or substantially, the disadvantages outlined in the previous paragraphs. Accordingly, the invention provides a plastics container having a plane upper surface provided by an outwardly projecting flange surrounding the container mouth, characterised in that the flange is peripherally shaped to provide a plurality of regularly spaced lobes for individual camming engagement with a like plurality of screw-thread formations of a multi-start screw thread on a closure fitted on the container over the container mouth.

This invention also provides a container as defined above having a plane diaphragm closure attached to its said upper surface and furthermore having a screw closure overlying the diaphragm, the closure having a said multi-start screw thread engaged with the lobes to attach the closure to the container in overlying relation to the diaphragm closure.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a view, partly on a diametral section and partly in side elevation, of a food product container in accordance with the invention, having its mouths closed by a diaphragm closure and by a screw closure overlying the diaphragm closure; Fig. 2 is an upper plan view of the container; and Figs. 3 and 4 are respectively an under plan view and part of an expanded section of the screw closure.

Referring now to the drawings, a container 10 for cocoa, drinking chocolate, coffee or like particulate food product is injection-moulded from polypropylene. It has a tubular side-wall 11 extending betweent the container mouth at its top end (as shown) and the container base at its bottom end. The base is closed by a substantially plane and transverse base panel 1 2 which is attached to the side wall a smal! distance up the height of the latter. The container accordingly has a recessed bottom, and a free terminal edge 13 of the side wall which provides it with a stable standing surface.

The container is generally circular in crosssection, being centred on an axis XX which is vertical (as shown) when the container is supported by its bottom edge 13 from a horizontal surface. The side wall 11 is substantially rightcylindrical, but to assist moulding is given a slight outward taper in the upward direction.

Transversely of the axis XX the only noncircularity of the container is provided by the free outer edge 14 of a flange 1 5 which projects outwardly from the side wall around the container mouth. The flange is directed transversely of the axis XX and, within moulding tolerances, is of constant thickness. Its upper surface 1 6 provids a plane terminal surface for the container; its lower surface, parallel to the upper surface 16, is denoted by the reference numeral 1 9.

As can clearly be seen from Fig. 2, the free outer edge 14 of the flange 1 5 is circular except at four identical lobes 17 where the flange is of increased radial depth. The lobes are regularly disposed around the flange and individually subtend an angle of about 400 at the axis XX. The flange is accordingly formed of the four lobes 1 7 arranged in two paris of diametrically disposed lobes, and four annular portions 18 which are alternate with the lobes and which merge with the lobes at their ends. As shown, each lobe is regular, that is to say, it is symmetrical about a radial plane directed axially of the container; in a modification, however, the lobes are non-regular.

An hermetic seal for the container is provided by a plane flexibie diaphragm 20 (Fig 1) which closes the container mouth. The diaphragm is shaped to conform to the free edge 14 of the flange, and has the peripheral margin where it overlies the flange heat-sealed to the flange upper surface 1 6. Although not apparent from the drawings, the diaphragm is formed from laminated sheet material having a paper and/or foil centre between layers of plastics film on either side. The bond between the diaphragm and the container is formed between the flange and the lower one of these plastics layers in known manner, by the application of heat and pressure.To open the container for use, the diaphragm may be severed around the inside of the flange, or alternatively the bond may be arranged to rupture so that the whole diaphragm can be pulled away; to that end a pull tab (not shown) may be provided on thg diaphragm.

To provide protection for the diaphragm closure to the point of use and to provide a reclosure for the container when the diaphragm closure has been removed in whole or in part, the container is additionally provided with a circular screw closure 21 which is shown in position in Fig. 1 and of which the arrangement is apparent from Figs. 3 and 4.

Referring now to Figs. 3 and 4 in combination with Fig. 1, the screw closure is injection-moulded from polypropylene and has a generally plane closure panel 22 and a cylindrical skirt 23 depending from the panel periphery. On its ~ exterior surface the skirt is formed with knurls 24 (some of which are shown in Fig. 1 only) to assist gripping by the user. The interior surface of the skirt is formed with four equispaced and identical screw-thread formations 25 arranged in pairs of diametrically opposed formations and forming a four-start screw thread for the screw closure.

Although not apparent from the drawings it is to be understood that, as seen on a radial crosssection, the formations as moulded are drooped wards the mouth of the screw closure so that they can be jumped-out of the mould core when the closure is ejected after moulding.

Each formation 25 subtends an angle of approximately 650 at the centre of the screw closure so that adjacent formations are separated by approximately 250 of subtended angle. As seen in Fig. 4, which shows two of the formations as seen radially of the closure, each formation in side elevation is formed of a central portion 26 parallel to the closure panel 22, a downwardly inclined portion 27 extending to the leading end 28 of the formation, and an upwardly inclined portion 29 extending to the trailing end 30 of the formation.

The portions 29 are more steeply inclined than the portions 27 for the reason to become apparent later.

The diameter D of the internal bore of the skirt 23 is slightly greater than the maximum dimension F of the flange free edge 14 across a pair of opposed lobes 1 7. The smaller diameter d separating the formations 25 of each opposed pair is less than the dimension F but somewhat greater than the diameter f of the flange free edge 14 at the annular portions 18. Typical D, d, F and fare 82.5, 79.5, 82 and 78 millimetres respectively.

The screw closure is applied to the container initially or for reclosure in conventional manner, by turning it in a clockwise direction. When, during this movement the lobes 17 become vertically aligned with the spaces between the formations 25, the closure drops sufficiently to allow the leading ends of the formations to subsequently engage under the lobes so that further movement results in camming engagement of the downturned portions 27 with the lobes to force the screw closure downwardly onto the container mouth. The turning movement is continued until the central portions 26 ofthe formations underlie the lobes whereupon further movement is substantially prevented by the upturned portions 29 acting as stops.The formations are spaced beneath the closure panel 22 of the closure by a distance such that this engagement of the formations 25 with the lobes in attended by resilient deformation of those members. The resilience thereby introduced ensures that the closure is thereafter held firmly on the container against inadvertent removal.

For removal the screw closure is turned in the clockwise direction to again align the lobes 1 7 with the spaces between the formations 25, whereupon the closure may be lifted away from the container. The upturned portions 29 assist removal by riding over the lobes 17 as the closure is turned.

In a modification of the described arrangement, suitable for products for which an hermetic seal is not required, the diaphragm 20 is omitted. The screw closure is then provided with suitable means on the Underside of its closure panel 22 for effecting a seal with the container; for example, a flowed-in gasket, integral plug portion or separate sealing wad may be used.

Although particularly described in relation to injection-moulded containers having their mouth at their greatest cross section, the invention may have application to plastics containers moulded by other methods or having their mouth at a reduced diameter neck. Furthermore, a number of lobes other than four may be used. The screw closure may be of metal rather than plastics material.

Claims (12)

1. A plastics container having a plane upper surface provided by an outwardly projecting flange surrounding the container mouth, characterised in that the flange is peripherally shaped to provide a plurality of regularly spaced lobes for individual camming engagement with a like plurality of screw-thread formations of a multi-start screw thread on a closure fitted on the container over the container mouth.

2. A container as claimed in Claim 1, wherein the lobes are each regular and centred on an axially directed radial plane of the container.

3. A container as claimed in Claim 1 or 2, wherein the flange regions between the lobes are part-annular in form and merge into the lobes.

4. A container as claimed in Claim 1, 2 or 3, wherein the lobes are four in number.

5. A container as claimed in Claim 4 wherein each lobe subtends an angle of approximately 400 at an axis of the container.

6. A container as claimed in any preceding claim having its mouth closed by a plane diaphragm of flexible sheet material which is shaped to substantially conform to the flange and peripherally heat-sealed to the same.

7. A container as claimed in Claim 1 when fitted with a said closure.

8. A container and closure as claimed in Claim 7, wherein the multi-start screw thread comprises a plurality of formations each having a central portion generally parallel to a closure panel of the closure, a leading portion inclined form the central portion away from the closure panel, and a trailing portion inclined from the central portion towards the closure panel.

9. A container and closure as claimed in Claim 8 wherein the trailing portion of each formation is more steeply inclined relative to the closure panel than the leading portion.

10. A container and closure as claimed in Claim 8 or 9 wherein the formations are four in number.

11. A container and closure as claimed in Claim 10 wherein each formation subtends and an angle of approximately 650 at the centre of the closure.

12. A container substantially as herein described with reference to the accompanying drawings.

1 3. In combination, a container, diaphragm and screw closure, substantially as herein described with reference to the accompanying drawings.