GB1577663A - Closure - Google Patents

Description

(54) A CLOSURE (71) We, METAL BOX SOUTH AFRICA LIMITED, of Metal Box Centre, 25 Owl Street, Auckland Park, Johannesburg 2092, Transvaal Province, Republic of South Africa, (formerly of EDURA, 40 Commissioner Street, Johannesburg, Transvaal Province, Republic of South Africa), do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to a closure. More particularly, it relates to a closure for closing containers such as bottles, jars, cans, etc. in a sealed manner.

According to the invention there is provided a closure of plastics material for closing a container the closure having on its inside surface a projecting formation forming a shoulder against which there abuts a flowed-in gasket for making sealing contact with a container the flowed-in gasket being confined to only a part of the closure.

Conveniently, the closure has a circular base and a tubular skirt depending from the base and the projecting formation is radially inwardly spaced from the skirt and defines an annular recess in association with the skirt, the flowed-in gasket being received in the annular recess.

The projecting formation may be coaxial with the skirt and may have a convergent cross-sectional profile, the profile converging from the inside surface of the closure towards the free end of the formation.

The projecting formation may be bent over towards the skirt of the closure so that the annular recess thus defined between the projecting formation and the skirt is undercut at the projecting formation.

The closure may further include an annular ridge co-axial with the skirt and projecting radially inwardly from the skirt and axially inwardly from the base, the annular recess being defined between the annular ridge and the projecting formation.

The skirt may be provided with an internal screw thread whereby the closure can be screwed onto a screw-threaded container.

The projecting formation may be integral with the base of the closure.

The gasket may be of a suitable polyvinyl chloride material such as plastisol, or it may be of a water based rubber latex material.

In order that the invention may be more fully understood an embodiment thereof will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a cross-sectional side view of a closure on line I-I in Figure 2; and Figure 2 shows a bottom plan view of the closure.

Referring now to the drawings, reference numeral 10 generally indicates a moulded plastics closure having a circular base 12 and an internally screw-threaded round tubular skirt 14 depending from the base.

The base has integral therewith an axially inwardly protruding formation 16 co-axially arranged with respect to the skirt 14. The surface of the formation 16 facing the skirt 14 is undercut as shown in 16.1 in Figure 1 so that the formation is directed towards the skirt and has a convergent shape. The skirt 14 has a thickened base portion 18 adjacent the base 12 and forming an annular ridge within the closure interior. The height of this ridge is substantially the same as that of the formation 16.

The base is thus provided with an undercut annular recess 20 defined by the facing surfaces of the thickened portion 18 of the skirt and the formation 16, and the inner surface of the base between the formation and the thickened portion.

A flowed-in plastisol material forming a gasket 22 substantially fills the recess 20.

The gasket 22 is formed by squirting the plastisol material, when in a fluid form, into the recess 20, during relative movement, such as by rotation, between the closure and the squirting nozzle (not shown). It is then cured by heating it to a temperature of approximately 120-130"C for three minutes. Once cured, the plastisol material forms a resilient gasket.

The formation 16, by being undercut forms a shoulder which prevents the gasket 22 from peeling away from the base 12. The formation 16 also restricts the region in which plastisol material is required, thus substantially reducing the amount of plastisol required for forming a flowed-in gasket in the closure.

WHAT WE CLAIM IS: - 1. A closure of plastics material for closing a container, the closure having on its inside surface a projecting formation forming a shoulder against which there abuts a flowed-in gasket for making sealing contact with a container, the flowed-in gasket being confined to only a part of the closure.

2. A closure according to Claim 1, in which the closure has a circular base and a tubular skirt depending from the base and the projecting formation is radially inwardly spaced from the skirt and defines an annular recess in association with the skirt, the flowed-in gasket being received in the annular recess.

3. A closure according to Claim 2, in which the projecting formation is co-axial with the skirt.

4. A closure according to any one of the preceding claims, in which the projecting formation has a convergent cross-sectional profile, the profile converging from the inside surface of the closure towards the free end of the formation.

5. A closure according to Claim 4, in which the projecting formation is bent over towards the skirt of the closure so that the annular recess thus defined between the projecting formation and the skirt is undercut at the projecting formation.

6. A closure according to any one of Claims 2 to 5, which includes an annular ridge co-axial with the skirt and projecting radially inwardly from the skirt and axially inwardly from the base, the annular recess being defined between the annular ridge and the projecting formation.

7. A closure according to any one of Claims 2 to 6, in which the inner surface of the skirt is provided with screw threads by means of which the closure can be screwed onto a screw-threaded container.

8. A closure according to any one of the preceding claims, wherein the projecting formation is integral with the base of the closure.

9. A closure according to any one of the preceding claims, wherein the flowed-in gasket is of plastisol material.

10. A closure substantially as described in the specification and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. A flowed-in plastisol material forming a gasket 22 substantially fills the recess 20. The gasket 22 is formed by squirting the plastisol material, when in a fluid form, into the recess 20, during relative movement, such as by rotation, between the closure and the squirting nozzle (not shown). It is then cured by heating it to a temperature of approximately 120-130"C for three minutes. Once cured, the plastisol material forms a resilient gasket. The formation 16, by being undercut forms a shoulder which prevents the gasket 22 from peeling away from the base 12. The formation 16 also restricts the region in which plastisol material is required, thus substantially reducing the amount of plastisol required for forming a flowed-in gasket in the closure. WHAT WE CLAIM IS: -

1. A closure of plastics material for closing a container, the closure having on its inside surface a projecting formation forming a shoulder against which there abuts a flowed-in gasket for making sealing contact with a container, the flowed-in gasket being confined to only a part of the closure.

2. A closure according to Claim 1, in which the closure has a circular base and a tubular skirt depending from the base and the projecting formation is radially inwardly spaced from the skirt and defines an annular recess in association with the skirt, the flowed-in gasket being received in the annular recess.

3. A closure according to Claim 2, in which the projecting formation is co-axial with the skirt.

4. A closure according to any one of the preceding claims, in which the projecting formation has a convergent cross-sectional profile, the profile converging from the inside surface of the closure towards the free end of the formation.

5. A closure according to Claim 4, in which the projecting formation is bent over towards the skirt of the closure so that the annular recess thus defined between the projecting formation and the skirt is undercut at the projecting formation.

6. A closure according to any one of Claims 2 to 5, which includes an annular ridge co-axial with the skirt and projecting radially inwardly from the skirt and axially inwardly from the base, the annular recess being defined between the annular ridge and the projecting formation.

7. A closure according to any one of Claims 2 to 6, in which the inner surface of the skirt is provided with screw threads by means of which the closure can be screwed onto a screw-threaded container.

8. A closure according to any one of the preceding claims, wherein the projecting formation is integral with the base of the closure.

9. A closure according to any one of the preceding claims, wherein the flowed-in gasket is of plastisol material.

10. A closure substantially as described in the specification and as illustrated in the accompanying drawings.