Containers and closures

1. A closure comprising:

(a) a top wall and a side wall depending from said top wall;

(b) a plug seal device depending from said top wall within said side wall;

said plug seal device having an upper section, a lower section, and a sealing section proximate the boundary between said upper section and said lower section;

said sealing section operable such that when said plug seal device is inserted in an opening to an inner cavity in a container, said sealing section engages with an inner container surface to provide a seal between an inner cavity of said container and the external environment;

said sealing section is formed as an annular protrusion extending radially beyond an outward surface of each of said upper and lower sections of said plug seal device; and

said lower section is configured and operable when being inserted into said opening, to provide axial alignment of said closure with said container prior to engagement by said sealing section with said inner container surface;

wherein an outward facing surface of said lower section comprises a plurality of vertically extending rib members extending below said sealing section, said plurality of rib members configured to define at least one channel there between, operable to vent fluid and/or gas when said sealing section is not in sealing engagement with said container surface.

2. A closure as claimed in claim 1 wherein said top wall comprising an annular groove in an inner surface of said top wall located proximate and inward to the location where said upper section of said plug seal device is joined to said top wall, said annular groove being operable to provide reduced stiffness to bending of said plug seal device relative to said top wall, when said top wall is subjected to forces resulting from increased pressure within said container when said closure is sealing said container.

3. A closure as claimed in claim 1 , wherein said sealing section comprises a ring shaped member having an arcuate outer sealing surface.

4. A closure as claimed in any of claims 1 wherein said lower section has a generally cylindrical outer surface.

5. A closure as claimed in any one of claims 1 wherein said upper section has a generally cylindrical outer surface.

6. A closure as claimed in claim 5 wherein said outer diameter of said upper section is greater than the outer diameter of said lower section.

7. A closure as claimed in claim 1 wherein said upper section has a wall thickness that is greater than the wall thickness of the lower section.

8. A closure as claimed in claim 7 wherein said top section has a wall thickness greater than said upper section of said plug seal device.

9. A closure as claimed in claim 1 wherein said initial seal is said only seal between said closure and said container surface of said container.

10. A closure as claimed in claim 1 wherein said container surface of said container is an inner surface of said container.

11. A closure as claimed in claim 1 wherein said lower section is configured and operable to assist in maintaining substantial axial alignment of said closure and said container while said sealing section is being moved into engagement with said inner container surface of said container.

12. A closure as claimed in claim 1 wherein said closure has at least one thread on an interior surface of said side wall, said at least one thread of said interior surface of said side wall operable to releasably engage with a complementary thread on an outward facing surface of said container, and wherein said closure is operable such that said plurality of rib members defines said at least one channel to vent said fluid and/or gas when said sealing section is no longer is in sealing contact with the said inner container surface whereby a passageway is defined through said at least one channel between the plug seal device and said container inner surface to allow the escape of said fluid and/or gas past said complimentary threads to the external environment.

13. A system for making a closure as claimed in claim 1 , said system comprising a first mold half and a second mold half, said first and second mold halves being configured and operable to be movable relative to each other between (i) a first position which creates a mold cavity when said first and second mold halves are in a closed relationship to each other wherein a molded closures may be formed in the mold cavity and (ii) a second position where said first and second mold halves are in a separated relationship wherein a molded closure molded in said mold cavity can be removed from said mold cavity.

14. A system as claimed in claim 13 further comprising an injection unit operable to inject an injection material for forming said closure into said mold cavity when said first and second mold halves are in said closed relationship to each other.

15. A system as claimed in claim 13 further comprising a clamping unit operable to clamp said first and second mold halves in said closed relationship to each other when said injection unit is injecting said injection material into said mold cavity.