GB2131774A

GB2131774A - Improvements relating to closures for bottles and other containers

Info

Publication number: GB2131774A
Application number: GB08332572A
Authority: GB
Inventors: Peter Reginald Haines
Original assignee: Metal Closures Ltd
Current assignee: Arconic Closure Systems International UK Ltd
Priority date: 1982-12-14
Filing date: 1983-12-07
Publication date: 1984-06-27
Also published as: GB8332572D0; GB2131774B

Abstract

A closure for a bottle or other container is moulded in one piece from a flexible resilient plastics material and has a sealing fin 14 which extends from the region of the junction between the top and the skirt and which is inclined radially inward and away from the top 10. The underside of the sealing fin is formed with sealing ribs 15 which are of triangular section. Above the screw- thread ridge 12 in the internal surface of the skirt a shoulder 20 is formed and its radially inwardly facing surface is formed with sealing ribs 21 for engaging the cylindrical surface of the neck of the container above its screw- thread. Further sealing ribs 22 are formed between the shoulder 20 and the root of the sealing fin 14. A groove 24 confines inward or outward doming of top 10 to the central area thereof. <IMAGE>

Description

SPECIFICATION Improvements relating to closures for bottles and other containers This invention relates to closures for containers and has a particularly useful but not exclusive application in closures for bottles intended to contain carbonated or still beverages.

According to this invention there is provided a container closure moulded from a resilient plastics material and having a top, a depending peripheral skirt, and a flexible annular sealing fin extending from the region of the junction between the top and the skirt and inclined radially inward and away from the top, said fin having on its lower surface a plurality of annular sealing ribs, and the portions of the underside of the top axially aligned with the sealing fin being continuous and substantially planar.

The sealing fin may extend from said junction, or from either the top or the skirt at a location adjacent said junction. If the container on which the closure is to be used is to hold carbonated liquids, and the sealing fin extend-either from the junction or from the top of the closure the annular groove may be provided on the underside of the top at a location radially inward of the root portion of the sealing fin so as to localise doming of the top under the pressure within the container substantially to the area enclosed by the annular groove.In this way any tendency for the root of the fin to be lifted due to doming of the top and any consequent loss of sealing pressure between the fin and the top of the container are reduced such an annular groove can similarly be employed where the container is a vacuum container to mitigate any adverse effects on the seal resulting from inward doming of top due to the vacuum within the container.

In one arrangement according to the invention, the radially inner surface of the skirt is formed with a screw-threaded ridge and an annular portion of the skirt above the ridge extends radially inward beyond the screw-thread ridge for forming a seal with the container neck. Preferably this annular portion of the skirt is formed with one or more inwardly projecting annular sealing ribs. Where the sealing fin depends from the top of the closure, the portions of the underside of the top between the root of the sealing fin and said annular portion of the skirt above the screwthread ridge are formed with annular sealing ribs.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawing which shows a sectional view of a closure according to the invention.

Referring to the drawing, the closure is moulded in one piece from a resilient plastics material and has a top 10 with a depending skirt 1 A screw thread ridge 12 is formed on the internal surface of the skirt, and the external surface of the skirt has serrations 1 3 to provide improved manual grip.

A flexible annular sealing fin 14 extends from the underside of the top adjacent its junction with the skirt and is inclined downwardly and radially inwardly. The underside of the fin is formed with triangular-section ribs 1 5 and a V-section groove 1 6 is defined between each pair of adjoining ribs.

The radially inwardly facing wall 1 7 of these grooves is inclined inwardly and upwardly at a small angle of approximately 10 to the central axis of the closure.

A shoulder 20 is formed on the internal surface of the skirt above the screw-thread and extends up to the junction with the top. The radially-inwardly facing surface of the shoulder has annular triangular-section sealing ribs 21 which project inward beyond the screw-thread ridge 12 for the purpose of making sealing contact with the cylindrical surface of the neck of the bottle above its screw-thread. The part of the underside of the top between the shoulder and the root of the sealing fin is similarly provided with triangularsection sealing ribs 22.

When the closure is applied to the externally threaded neck of a bottle the top of the neck comes into sealing engagement with the ribs 1 5 on the sealing fin 14 and the ribs 21 on the shoulder 20 form a seal with the side and corner portions of the neck above the screw-thread.

Upward deflection of the fin 1 9 is limited by the top, the parts of the undersurface of which axially aligned with the fin are continuous (i.e. devoid of interruptions such as ribs and grooves) and are substantially planar.

An annular groove 24 may be formed in the underside of the top 10 at a location radially inwardly of the portions thereof which may come into contact with the sealing fin 14. Such a groove forms an annular hinge enabling upward or downward bulging of the central area of the top to take place without substantially affecting the outer portions of the top and hence the backing force afforded to the sealing fin thereby.

The neck of the bottle is formed in a multi-part mould the various parts of which are required to move relative to each other and are therefore provided with appropriate clearances, and these clearances produce flashing which interrupts the smooth curves which are desirable at the radially inner and outer edges of the top of the neck. The shape of the grooves 1 6 resulting from the undercut form of the ribs on the lower surface of the fin is thought to be particularly beneficial in providing surfaces which operate to deflect the flashing into the grooves 16 where it is accommodated and does not interfere with the formation of a gas-tight seal.

The shoulder 20 may be omitted in some cases since the friction between the ribs 21 and the bottle may increase to an unacceptable value the torque necessary to remove and/or replace the closure, and in other cases where the bottle has what is known as an extended finish i.e. where the thread extends to a point so close to the end of the neck to leave an insufficiently long cylindrical sealing surface on the bottle.

Claims

1. A container closure moulded from a resilient plastics material and having a top, a depending skirt, and a flexible annular sealing fin extending from the region of the junction between the top and the skirt and inclined radially inward and away from the top, said fin having on its lower surface a plurality of annular sealing ribs, and the portions of the underside of the top axially aligned with the sealing fin being continuous and substantially planar.

2. A closure as claimed in claim 1 wherein the radially inner surface of the skirt is formed with a screw-thread ridge and an annular portion of the skirt above the ridge extends radially inward beyond the screw-thread ridge for forming a seal with the container neck.

3. A closure as claimed in claim 2, wherein said annular portion of the skirt is formed with one or more inwardly projecting annular sealing ribs.

4. A closure as claimed in any one of claims 1 to 3, wherein the sealing fin depends from the top of the closure.

5. A closure as claimed in claims 4 and 5 wherein the portions of the underside of the top between the root of the sealing fin and said annular portion of the skirt above the screwthread ridge are formed with annular sealing ribs.

6. A closure as claimed in any one of claims 1 to 5 wherein the sealing ribs are of triangular cross-section.

7. A closure as claimed in claim 6, wherein the sealing ribs on the underside of the sealing fin are adjacent each other so as to form triangular section grooves between adjoining ribs, the radially outer walls of which grooves are inclined towards the top of the closure.

8. A closure as claimed in any one of claims 1 to 7, wherein an annular groove is formed on the underside of the top at a location radially inward of said planar portions of the top.

9. A container closure substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.