CAP AND CAP/CONTAINER COMBINATION

Abstract: In order to prevent "missiling" of the cap of a bottle or other screw-top container intended to contain a carbonace­ ous beverage, the screw-thread ridge 11 on the neck 13 of the container has one or more transverse notches 12 in its length so as to relieve the gas pressure as the cap is removed. The radial depth of the notches may conveniently be equal to the radial height of the screw-thread ridge in which it is formed. Notches in adjoining turns of the ridge may be circumferen­ tially staggered. Additionally or alternatively the screw-­ thread ridge in the screw-cap for the container may be pro­ vided with similar notches in its length.

Description: "IMPROVEMENTS TN OR RELATING TO CONTAINERS HAVING SCREld-THREADED NECKS AND TO CAPS FOR SUCH CONTAINERS" This invention relates to containers, more particularly bottles, having screw-threaded necks and to caps for such containers. When a screw-capped bottle containing a carbonated beverage is partly empty the liquid is more susceptible to shaking and disturbance, causing the carbon dioxide to come out of solution and create a substantial gas pressure in the bottle. It is well-known that the gas pressure may be sufficient to blow the cap out of the hands as the cap is unscrewed. The cap is thus potentially a missile capable of inflicting serious damage on property and person. According to this invention there is provided a container having a screw-threaded neck the screwthread ridge of which is forrred with one or more transverse notches in its length. In another aspect the invention provides a screwcap the screw-thread ridge of which is formed with one or more transverse notches in its length. Such caps will normally be moulded from plastics materials. The invention also provides a container having a screw-threaded neck and a screw-threaded cap screwed on to said neck, the ridge of the screwwthread of the cap and/or of the container having one or more transverse notches in its length. Thus excess pressure in the container can be relieved during removal of the cap, as gas escapes across the screw-thread by way of the notch or notches. It is preferred to provide a plurality of said notches, and notches in successive turns of the thread may be formed in axial alignment with each other so as to shorten the escape path. However, where the notches are formed in the screw-thread on the container, and the cap is a metal cap rolled on to the thread, the notches should not be of such size as to produce a complementary formation on the cap, and it may be preferable also that the notches in each turn of the thread be circumferentially staggered with respect to those in the other turn or turns so that minor irregularities in the thread on the screw-cap resulting from the rolling-on process are widely distributed along the thread and do not lead to "lumpy" movement of the cap during removal and replacement. The notch or notches may have a radial depth equal to or less than the radial height of the threadforming ridge. The distances measured along the ridge between adjacent notches may differ. For example the distances between adjacent notches may be greater at either end of the ridge than the other. Some embodiments of the invention are shown in the accompanying drawings and will now be described by way of example. In the drawings: Figures 1 and 3 each show diagrammatically the neck portion of a container according to the invention, Figures 2 and 4 are plan views corresponding to the threaded portion of Figures 1 and 2 respectively, and Figures 5 and 6 are respectively a sectional elevation and underneath plan of a cap embodying the invention. The container whose neck portion 10 is shown is in the form of a bottle with an external helical ridge 11 constituting a screw-thread. At intervals along its length notches 12 are formed in the ridge. The portion 13 of the neck has, in the manner wellknown in the art, a closely controlled external diameter and forms a seal with a complementary screwcap (not shown). During removal of the cap, the seal at 13 is broken whilst the screw-threads on the cap and bottle are still well engaged, and any pressure in the bottle is then relieved by flow of gas past the sealing surfaces and thence through the notches 12 and round the profile of the complementary thread-constituting ridge of the cap. The cap may be made from metal sheet and have a screw-thread rolled on to it, in the well-known manner, in substantial conformity with the thread on thebottle, except for the notches 12, the dimension of which lengthwise of the thread ridge should not be as to produce any corresponding interruption of the thread on the cAp. If desired, where the cap of the container is moulded from plastics material, the thread-constituting ridge of the cap may also be formed with notches similar to the notches 12. Alternatively the cap thread may be notched and the bottle thread unnotched. The bottle may additionally have a peripheral rib (not shown) for the formation of a rolled-on pilferproof band, but the rib is immaterial to the invention. Figures 5 and 6 show a cap 15 according to the invention. The cap is moulded from a suitable plastics material and has an internal screw-thread ridge 16 which is formed with a series of transverse notches 17 spaced along its length. The radial depth of the notches is equal to the radial height of the ridge 16. Such a cap can be used with a bottle having a conventional uninterrupted screw-thread ridge or with bottles such as are illustrated in Figures 1 to 4. Annular ribs 18, 19 and an annular surface 20 are provided to form a pressure-tight seal with the uppermost portions of the bottle neck.

Claims: LATHS 1. A container having a screw-threaded neck, and a screw-threaded cap engaged on said neck, so that the container and cap each have a screw-thread ridge, characterised in that the said ridge on the cap and/or on the container neck is formed with one or more transverse notches in its length. 2. A container as claimed in claim 1, characterised in that the notched ridge on the container and/or on the cap extends in more than one screw turn, the notches in successive turns of the ridge being axially aligned. 3. A container as claimed in claim 1, characterised in that the notched ridge on the container neck or on the cap extends in more than one screw turn, the notches in successive turns of the ridge being circumferentially staggered. 4. A container as claimed in any one of claims 1 to 3, characterised in that each notch has a radial depth substantially equal to the height of the ridge.

Inventors: GUEST, JOHN HARRY
Applicants: METAL CLOSURES LIMITED
Application year: 1979
Main classification: B65D51
IPC codes: B65D51, B65D41