GB2111470A

GB2111470A - Containers

Info

Publication number: GB2111470A
Application number: GB08138128A
Authority: GB
Inventors: Adrien Patrick Rayner
Original assignee: Metal Box PLC
Current assignee: Crown Packaging UK Ltd
Priority date: 1981-12-17
Filing date: 1981-12-17
Publication date: 1983-07-06
Also published as: GB2111470B; ZA829248B

Abstract

A paint container has a plastics lid engaged in a metal lever ring of the container body. The lid has a in peripheral flange 15 and a snap-in bead 28 spaced from the flange by the generally cylindrical sealing surface 14 of the lid. In order substantially to reduce pressure differences between the interior and exterior of the container, the bead is segmented and vent formations in the form of ribs or grooves 31 extend between the bead segments and the flange. When the lid is fitted the vent formations provide vent passages enabling equalising gas to flow through the interface between the lid and the lever ring. The passages are such, however, as to be closed off by any paint which attempts to pass through them. <IMAGE>

Description

SPECIFICATION Containers This invention relates to containers for skinforming substances such as paint. The invention has particular (but not exclusive) applications to such containers having a lever ring on the container body and defining the container mouth and a lid which is adapted to close the container by plug fit engagement in the lever ring. The lever ring may be formed integrally with the container body or it may be separate but attached thereto by, for example, double-seaming.

Proposals to provide paint containers with plastics lids have hitherto been hampered by the tendancy of the lid (and the container body if wholly or partially of plastics) to deform inwardly or outwardly in response to differential pressures between the container interior and exterior. Such pressure differences may occur at various times between the intitial application of the lid to the container by the paint manufacturer, and the eventual discarding by the consumer when the container is empty. Often the resulting distortion of the container will go unnoticed and will not result in any significant deterioration of the functional capabilities of the container or its suitability for its intended task; in such circumstances the distortion as such can be tolerated.However, distortion which is present in the paint manufacturer's plant after the container has been lidded may prevent satisfactory palletising or stacking of the containers for storage or transit, and may subsequently reduce the saleability of the containers. In particular for a container which is partially or wholly of plastics material there therefore exists a need for a means to allow venting for pressure equalisation without any concomitant tendancy for the product to leak from the container if the latter is upturned or shaken.

Accordingly, from a first aspect, there is provided a container for a skin forming substance, which comprises a body and a lid to seal the body closed by mutual engagement of sealing surfaces of the body and lid, at least one of the said surfaces being formed with a vent formation arranged, when the lid is fitted to the body with the surfaces in engagement, to provide a vent passage which extends along the interface of the surfaces to communicate the interior of the container with the container exterior, but which is of such a size as to be closed off by any of the skin forming substance which attempts to pass therethrough.

In a preferred embodiment of the invention the lid is of synthetic plastics material and is formed with a said vent formation. Accordingly, from a second aspect the invention provides a plastics lid for a container of paint or other skin forming substances, which has a surface for sealing engagement with a sealing surface of the container body, the said sealing surface of the lid being formed with a vent formation arranged, when the lid is fitted to the body with the said sealing surfaces in engagement, to provide a vent passage which extends along the interface of the surfaces to communicate the interior of the container with the container exterior, but which is of such a size as to be closed off by any of the skin forming substance which attempts to pass therethrough.

These and other aspects and features of the invention will become apparent from the following description of embodiments thereof, described by way of example and with reference to the accompanying drawings, wherein: Fig. 1 shows a plastics lid for a fitting to a metal lever ring of a paint container body; Fig. 2 is a scrap view of the lid when engaged with the lever ring, as seen on a tangential section taken on the line Il-Il of Fig. 1; Fig. 3 is a further sectional view of the lid and lever ring engagement, as seen on horizontal section Ill-Ill of Fig. 2; Fig. 4 is a view similar to Fig. 2 of a modified plastics lid; and Fig. 5 is a view of the modified lid as seen on section V-V of Fig. 4.

Referring firstly to Fig. 1, a circular lid for a paint container is injection-moulded from a suitable thermoplastics material such as high density polyethylene. It has a plane central panel 10, and a portion 11 which surrounds the panel 10 and forms an upwardly-open channel 12 around the lid periphery.

As can clearly be seen from Fig. 2, the channelforming portion has generally cylindrical (but slightly tapering and convergent inner and outer skirts 13, 14 and a web 1 5 joining the bottom ends of the skirts so as to form the base of the channel. The top end of the inner skirt 13 is connected to the periphery of the central panel 10, whereas the top end of the outer skirt 14 carries a plane annular flange 1 5 providing the free edge 1 6 of the lid. The flange 1 5 is located so that its upper surface 1 7 stands slightly proud of the upper surface 1 8 of the central panel 10.A groove 1 9 formed around the channel-forming portion 11 at the junction of the outer skirt 14 and flange 1 5 provides location for the lids when stacked on top of one another. It similarly serves as a stacking feature for the lidded and productfilled containers. Such stacking is accommodated by the recessing of the central panel 10 in relation to the flange 1 5.

Fig. 2 shows the central panel 10 and channelforming portion 11 in relation to the metal lever ring 21 of a paint container body. The body may be conventional and accordingly is not shown in fuli; it may thus comprise a fabricated metal side wall with a longitudinal seam, a metal end closure closing the bottom end of the side wall and double-seamed to the same, and the lever ring 21 double-seamed to the top end of the side wall.

The lever ring 21 conventionally has a plane, annular main panel 22 extending to connection with the container side wall at its outer edge (not shown), and a vertically elongate, solid bead or rib 23 having a cylindrical inner portion 24 which defines the inside periphery of the lever ring and accordingly the dimension of the container mouth. The cylindrical portion 24 is joined to the outer periphery of the panel 22 by an arcuate portion 25; at its top end it carries an outturned curl 26 extending to the terminal edge 27 of the lever ring material.

When as shown in Fig. 2, the lid is fitted into the lever ring 21 to close the container, the outer skirt 1 4 of the lid makes an interference fit in the cylindrical portion 24 of the lever ring so as to create a seal between them against escape of paint from the container. The flange 1 5 is available to limit the entry of the lid into the container by engagement with the curl 26 as shown.Inadvertent or unauthorised removal of the lid is prevented or impeded by a bead 28 which is formed around the exterior of the channel-forming portion 11 at the base of the outer skirt 14; the bead 28 is profiled so as to ride down the lid bead 23 when the lid is applied, and thereafter to be able to ride up the bead 23, but with difficulty, when the lid is removed in the normal way by an implement engaged between the main panel 22 of the lever ring and the free undersurface presented by the flange 1 5 of the lid.

In order to prevent it from generating a substantial super-atmosphere or sub-atmospheric pressure in the container by piston action when the lid is applied or removed, the bead 28 is segmented at a plurality (e.g. 6) of discontinuities 30 (Fig. 1) which allow gas to pass the bead 28 when it is moving across the inner cylindrical surface of the lever ring bead 23. However, as described above, when the lid is fully in position on the container, the required seal between the lid and container is provided between the opposed cylindrical surfaces of the lid outer skirt 14 and the portion 24 of the lever ring bead 23, and in such circumstances the discontinuities 30 are ineffective for pressure equalisation. Pressure equalisation is then provided by solid vertical ribs or heads 31 of which one is provided for each segment 32 of the bead 28.As is apparent from Figs. 1 and 2, each vertical bead 31 is moulded to project from the outside surface of the outer skirt 14 and extend longitudinally between the flange 1 5 at its top end and the centre of the respective bead segment 32 at its bottom end.

Figure 3 shows one of the ribs 31 in relation to the adjacent part of the cylindrical portion 24 of the lever ring bead 23. It will be seen that the ribs 31 locally holds the lid material clear of the lever ring so as to form a pair of shallow passages 34 disposed one to each side of the rib. These passages, which are shown exaggerated for clarity, provide for two gas flow in the appropriate direction along the otherwise hermetic seal provided between the lid and the lever ring as described above, and in this way allow for pressure equalisation when the lid is in position.

In order to ensure that the passages 34 cannot be obstructed by the flange 1 5 when the lid is fully inserted into the container mouth, the ribs 31 may be continued across at least part of the undersurface of the flange as shown in Fig. 2; likewise, for a similar reason, they may be continued across the upper flanks of their respective bead segments 32.

Each rib 31 may be of any suitable profile (e.g.

semi-circular or triangular), but it should be such that the passages 34 which it forms are sufficiently shallow to be closed off by any paint which enters them, by virtue of the skin-forming properties of the paint. In general, the more viscous and quicker-drying the paint, the greater the depth of the passages 34 which can be used without incurring the risk of paint leakage. A typical depth for the passages is 0.125 mm.

adjacent the rib 31, the rib itself being of appropriate height, with allowance made for any deformation of the rib by virtue of the substantial pressure exerted by the lever ring.

The ribs 31 shown in the drawing have a width which is substantially the same as their height and typically of the order of 0.15 mm. Such a rib will be subject to substantial deformation by the lever ring. However, by increasing the width of the ribs to 1 cm. (for example), to facilitate moulding the ribs become substantially undeformable by the lever ring, and the height of the vent passages 34 is then substantially equal to the height of the ribs.

From the above description it will be appreciatesi that the discontinuities 30 in the bead 28 together with the passages 34 generated by the ribs 31 will substantially reduce the levels of pressure differential which can exist between the exterior and interior of the container. Because of there will be little or no likelihood that distortion of the container (in particular, of the lid) caused by differential pressure will be of such magnitude to affect the function or aesthetic appeal of the container, or prevent its satisfactory handling and storage between paint manufacturer and consumer. In particular, the ability of the containers to be stacked on top of one another on pallets after filling and lidding is assured.

When the lid is first applied to the container in the paint manufacturer's plant, the bead segments 32 wipe the opposed surface of the lever ring 21 clear of any paint which may have slopped onto it during and after filling. By virtue of the location of the ribs 31 above the segments 32, there is therefore little or no paint available to cause premature blockage of the passages 34 before the containers are stacked and palletised.

Figs. 4 and 5 shows a modification of the lid of Figs. 1 to 3 in which the ribs 31 are replaced by grooves 310 formed in the skirt 14. As will be apparent from Fig. 5, the required equalising gas flow across the interface between the lid and the lever ring is now accommodated by the grooves 310 themselves. The grooves are of sufficiently small cross-sectional dimensions to be closed off by any paint which attempts to leak through them; the ability of the container to hold paint without leakage is thereby again assured. By way of example the grooves are shown to extend along the supper flank of the bead 28 but not along the undersurface of the flange 15; however, it will be appreciated that if desired the grooves may extend along the flange 1 5 and/or not along the bead 28.

The invention is not limited in application to paint containers having plastics lids and metal lever rings as particularly described. It may be used in relation to skin forming substances other than paint, and may use closure combinations other than plug lids in lever rings. One or more vent passages forming formations, viz. the ribs 31 and grooves 310, may be provided, and these formations may be located on the container body instead of, or in addition to, the closure. The formation or formations may be provided for plastics/plastics or metal/metal interfaces, as well as for metal/plastics interfaces as particularly described.

Claims

1. A container for a skin forming substance, which comprises a body and a lid to seal the body closed by mutual engagement of sealing surfaces of the body and lid, at least one of the said surfaces being formed with a vent formation arranged, when the lid is fitted to the body with the surfaces in engagement, to provide a vent passage which extends along the interface of the surfaces to communicate the interior of the container with the container exterior, but which is of such a size as to be closed off by any of the skin forming substance which attempts to pass therethrough.

2. A plastics lid for a container of paint or other skin forming substance, which has a surface for sealing engagement with a sealing surface of the container body, the said sealing surface of the lid being formed with a vent formation arranged, when the lid is fitted to the body with the said sealing surfaces in engagement, to provide a vent passage which extends along the interface of the surfaces to communicate the interior of the container with the container exterior, but which is of such a size as to be closed off by any of the skin forming substance which attempts to pass therethrough.

3. A lid in accordance with claim 2, which has a flange to limit entry of the lid into the container, there being a bead formed around the sealing surface at a spacing from the flange and arranged to prevent or impede inadvertent or unauthorised removal of the lid from the container, the vent formation extending between the flange and the bead.

4. A lid in accordance with claim 3, wherein the bead is segmented at a plurality of discontinuities spaced therearound, the vent formation corresponding, peripherally of the lid, to a segment of the bead.

5. A lid in accordance with claim 4, which includes a plurality of the said vent formations equal in number to the bead segments, each vent formation corresponding, peripherally of the lid, to a respective bead segment.

6. A lid in accordance with any claim of claims 3 to 5, wherein the vent formation is continued from the sealing surface onto the adjacent surface of the flange.

7. A lid in accordance with any claim of claims 3 to 6, wherein the vent formation is continued from the sealing surface onto the adjacent flank of the bead.

8. A lid in accordance with any claim of claims 2 to 7, wherein the vent formation comprises a rib formed as a projection on the sealing surface and arranged, when the said surfaces are in engagement, to hold the surfaces locally apart and thereby create a said vent passage down each side thereof.

9. A lid in accordance with any claim of claims 2 to 7, wherein the vent formation comprises a groove formed in the sealing surface to provide a said vent passage.

10. A lid in accordance with any claim of claims 2 to 9 when in combination with a metal lever ring providing the said sealing surface of the container body.

11. A lid for a container, substantially as hereinbefore described with reference to Figs. 1 to 3 of the accompanying drawings.

12. A lid for a container, substantially as hereinbefore described with reference to Figs. 4 and 5 of the accompanying drawings.

1 3. A lidded container, substantially as hereinbefore described with reference to the accompanying drawings.