IE43361B1 - Closure cap, particularly for containers having screw-threaded neck - Google Patents

Abstract

A screw on cap for bottle with suitably threaded necks has a top section (1) of varying thickness, the thickness decreasing towards the centre. A lip is formed on the inner surface so that it is pressed against the top surface of the neck of the bottle. A variation has a circular lip which fits inside the neck of the bottle. Another variation has two circular ribs with a groove between them, the ribs being directed inwards and outwards, to be pressed onto the bottle neck.

Description

The present invention relates to a closure cap particularly for a container having a screw-threaded neck, which cap comprises an end wall portion from the periphery of which extends a lateral skirt portion having an internal screw-thread to enable it to be screwed onto the neck of the container.

To enable a cap of this type to provide a completely tight seal it is at present necessary to fit therein a circular sealing element made of resilient material which bears against the inner surface of the top cover portion of the cap. A sealing element of this kind is intended to be compressed between the top of the cap and the end face of the neck when the cap is screwed on, so as to establish the seal. However, when a seal is established in this way, the cost is relatively high.

It ts in fact necessary to form the caps ahd the sealing elements separately and then to fit the latter into the various caps, and this calls for the use of several, generally very expensive machines and the employment of a relatively large work-force for carrying out the numerous handling operations.

The present invention aims at eliminating this disadvantage and, to this end the invention provides a cap for a container having a screwthreaded neck, said cap comprising an internally threaded skirt portion and an integrally formed substantially planar end wall of resilient plastics material extending across the whole cross-sectional area of the annular skirt portion ahd forming an end closure thereto, wherein both the internal and external faces of said end wall have a concave configuration, and wherein said internal face has upstanding therefrom an annular lip portion which when the cap is screwed onto the container sealingly engages the end face of the heck. - 2 4 3 3 61 This arrangement enables the cap to be used alone, that is to say, it is not necessary to provide it with an additional sealing element.

The machines previously used for producing sealing elements and for fitting them in the caps are therefore no longer required, and this enables the total cost of caps of the above-mentioned kind to be greatly reduced.

When the cap is screwed on to the neck of a container, the annular lip portion, because of its resilient nature, is resiliently deformed and, by becoming flattened against the end face of the neck, ensures that the container is sealed in a completely tight manner. Also, because of its reduced thickness at the centre due to the opposite concavities of the internal and external faces of the end wall, the end wall is resiliently deformed in the outward direction and tends to act like a spring. Consequently, axial pressure is set up between the screw-threads of the neck and those of the cap, and this enables the seal to be maintained even when the cap is accidentally unscrewed to a slight extent.

Furthermore, the cap can be used for tightly sealing containers having necks of varying thickness, the seal being established across the end face of the neck of the container to be closed.

The annular lip portion may be provided with annular ribs on that of its faces intended to be brought into contact with the end face of the neck.

A seal may thus be established in a very satisfactory manner even when the end face of the neck is not of perfectly regular shape. When the cap is screwed on, the annular ribs are elastically deformed and, by becoming flattened side-by-side against the end face of the neck, they tightly fill up any surface irregularities that may exist in said end face. - 3 4 3 3 61 In one embodiment, the annular lip portion is associated with an annular tongue, downwardly dependent from the inner periphery of the annular lip portion which tongue is adapted to move into close contact with the inner wall of the neck when the cap is screwed on to it. It will be readily 5 appreciated that an even tighter seal is established in this case since it is provided not only by an annular lip portion but also by the annular tongue.

In another embodiment, the internal face of the end wall has two concentric annular lip portions extending in opposite directions and separated by an annular channel.

Advantageously, the inner surface of the skirt portion may also have annular tongues adapted to move into close contact with the outer wall of the neck near the end face thereof, when the cap is screwed on to the neck of the container. It will be appreciated that the tongues also improve the seal by becoming deformed upwardly when the cap is screwed on.

Several embodiments of the present invention are illustrated by way of example in the accompanying drawings and will now be described in more detail.

In the drawings:Figures 1 to 3 are sectional views of a first form of closure cap in accordance with the invention, these Figures illustrating the fitting of the cap on a container having a screw-threaded neck; Figures 4 to 6 are views similar to those of figures 25 1 to 3 and show a second form of construction of closure cap; Figures 7 to 9 are again views similar to those of Figures 1 to 3 and show a third form of closure cap; and - 4 43361 Figures 10 to 12 are further views similar to those of Figures 1 to 3 and show, on a larger scale, a fourth form of construction of closure cap.

The various closure caps illustrated in the drawings each comprise an end wall 1 from the periphery of which extend an annular skirt portion 2 which has an internal screw-thread so that it can be screwed on to the screwthreaded neck 3 of a container such as a bottle. These caps are made of a resilient material, for example polypropylene, and they each have an end wall 1 the opposite faces of which are concave and which has on its inner face an annular lip 4 intended to bear tightly against the end face of the neck 3 when the cap is screwed on to the latter.

Referring first to the form illustrated in Figures 1 to 3, it will be seen that the cap has a single lip which forms an angle of approximately 30° with the median plane of the end wall 1, and that the latter is of generally concave form on both faces.

When the cap is screwed on to the container (Figure 1), the annular lip 4 moves towards the end face of the neck 3 and finally into contact therewith (Figure 2). Starting from this stage, a hermetic closure of the container begins to be effected. The lip 4 in face deforms elastically because of the nature of the material of which it is made and it flattens (Figure 3) against the end face of the neck thus establishing an excellent seal. During this time, the end wall 1, becuase of its reduced thickness towards its centre, also becomes elastically deformed towards the exterior and tends to act like a spring. Thus, if the cap is accidentally unscrewed to a slight extent, the lip 4 will continue to be firmly applied against the end face of the neck so that a completely tight seal is maintained. - 5 4 3 3 81 After the cap has been tightened the lip 4 forms an angle of approximately 45° with the median plane of the cover portion 1.

When the cap is unscrewed, the end wall 1 and the lip 4 will, of course, resume their original shapes.

In the second form of cap illustrated in Figures 4 to 6 the concave inner face of the end wall 1 has, in addition to the annular lip 4, an annular tongue 5 adapted to move into close contact with the inner wall of the neck when the cap is screwed on to the latter.

While the cap is being tightened, the lip 4 and the end wall 1 become resiliently deformed as explained above, whilst the annular tongue 5 enters the neck and thus improves the seal.

In the third form of cap illustrated in Figures 7 to 9, the concave inner face of the end wall 1 has two concentric annular lips 4 and 5, which extend in opposite directions and are separated by an annular channel 7. It will be readily appreciated that the presence of these two lips further improves the seal.

Finally, in the fourth form of cap illustrated in Figures 10 to 12, the annular lip 4 has a number of annular ribs 8 on that of its faces intended to move into contact with the end face of the neck. Furthermore, the inner surface of the skirt portion 2 has annular inwardly directed tongues 9 adapted to move into close contact with the outer wall of the neck 3 near the end face thereof, when the cap is screwed on.

When the cap is screwed on to the container, the ribs 8 fill up any irregularities which may be present on the end face of the neck, whereas the tongues 9 become upwardly deformed and move into close contact with - 6 « 3 3 61 the outer wall of the neck near the end face thereof.

It will thus be seen that containers haying screw-threaded necks can be hermetically closed by means of these caps, within which it is no longer necessary to provide a separate sealing element so that the number of handling operations during manufacture is reduced and the total cost of the caps can be considerably lowered.

Claims (6)

1. A cap for a container having a screw-threaded neck, said cap comprising an internally threaded skirt portion and an integrally formed substantially planar end wall of resilient plastics material extending across the whole cross-sectional area of the annular skirt portion and forming an end closure

2. A cap according to claim 1, wherein the annular lip portion is provided 10 with annular ribs on the face thereof which, in use, sealingly engages the end face of the neck.

3. A cap according to claim 1 or 2, wherein the annular lip portion has an annular tongue downwardly dependent from the inner periphery thereof, which tongue in use, sealingly engages inside the neck of the container. 15

4. A closure cap according to claim 1 or 2, wherein the internal face of the end wall has an additional concentric annular lip portion, said lip portions extend in different directions therefrom and are separated by an annular channel, which annular lip portions both sealingly engage the end face of the neck of the container when the cap is engaged thereon. 20

5. A cap according to any of the preceding claims wherein the inner surface of the skirt portion adjacent the juncture with the end wall is provided with an inwardly directed annular tongue which in use engages with the outer wall of the neck of the container near the end face thereof. - 8 43361 5 thereto, wherein both the internal and external faces of said end wall have a concave configuration and wherein said internal face has upstanding therefrom an annular lip portion which when the cap is screwed onto the container sealingly engages the end face of the neck.

6. A cap according to claim 1 substantially as hereinbefore described with reference to Figures 1 to 3 or Figures 4 to 6 or Figures 7 to 9 or Figures 10 to 12 of the accompanying drawings.