Container closure assembly with pressure seal
a container and sealing technology, applied in the direction of containers, caps, and closures using caps, can solve the problems of permanent deformation and damage of the cap, impaired subsequent sealing, and plastic deformation of the cap, and achieve the effect of constant torque, less abrupt increase in screwing torque, and right degree of resilience and strength
Inactive Publication Date: 2012-02-16
BEESON & SONS
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[0024]Suitably, the container lip is substantially fully radiused in longitudinal cross-section. That is to say, the longitudinal cross-section of the lip surface presents a substantially continuous curve extending from the inside surface of the neck to the outside surface of the neck, so that the top of the lip is rounded, not flat. More suitably, the surface of the lip is shaped substantially as a segment of a circle in cross-section, for example it may be substantially semi-circular. The rounded lip provides for easy and comfortable drinking directly from the container neck. It is a further advantage of the present invention that the sealing arrangement is effective to provide a pressure-tight seal on a rounded container lip by engagement of the concave inner surface of the sealing skirt on the rounded surface of the lip.
[0025]Suitably, the inner and / or the outer surfaces of the container neck adjoining the lip are slightly tapered. That is to say, the internal diameter of the neck adjacent to the bottom of the lip may be slightly tapered inwardly providing a substantially conical surface wherein the internal diameter decreases slightly with increasing distance from the junction with the (radiused part of) the lip. Suitably, this region of taper extends for an axial distance from about 1 mm to about 10 mm, for example about 2 mm to about 5 mm. so that the olive seal abuts against the tapered inside surface as the sealing position is approached when screwing the cap onto the neck. Similarly, the outer diameter of the neck adjacent to the bottom of the lip may be slightly tapered outwardly so that the outer diameter increases slightly with increasing distance from the junction with the (radiused part of) the lip. Suitably, this region of taper extends for an axial distance from about 1 mm to about 10 mm, for example about 2 mm to about 5 mm, so that the sealing skirt abuts against the tapered inside surface as the sealing position of the cap on the neck is approached. The angle of each taper, measured in longitudinal cross-section, is suitably independently from about 1 degree to about 30 degrees, more suitably from about 5 degrees to about 20 degrees from the longitudinal axis of the assembly. The slight taper of the neck below the lip results in a more constant torque being required to secure the cap on the neck close to the sealing position. In other words, there is a less abrupt increase in screwing torque as the sealing plug and sealing skirt first engage the neck.
[0026]The assembly according to the invention further comprises a cap having a base portion and a threaded skirt portion. The cap is suitably molded in one piece from thermoplastic material, for example by injection molding or by compression molding. The cap includes a sealing plug and a sealing skirt depending from the base of the cap, as defined above.
[0027]The sealing plug is suitably in the form of a tube, typically projecting perpendicularly downwardly from the base of the cap and preferably substantially concentric with the threaded skirt and coaxial with the longitudinal axis of the cap. The height of the sealing plug (measured from the inside surface of the base of the cap) is suitably from about 1 mm to about 5 mm, for example about 1.5 mm to about 2.5 mm. The sealing plug is normally molded integrally with the base of the cap. The mean thickness of the tubular wall of the sealing plug is suitably from about 0.5 mm to about 2 mm, for example about 0.7 mm to about 1.2 mm. This gives the sealing plug the right degree of resilience and strength for the desired sealing function.
[0028]The sealing plug is in the form of an olive seal. That is to say, the plug has a circumferentially projecting radially outer surface having a bulbous shape (when viewed in longitudinal cross-section). The bulbous projection has a substantially smooth, continuous surface and a height suitably from about 10% to about 50% of the radial thickness of the plug. The minimum radius of curvature of the bulbous projection is suitably no less than about the mean radial thickness of the plug. Suitably, the minimum radius of curvature of the bulbous projection is from about 0.5 mm to about 1 mm. Such olive sealing plugs are relatively tolerant of small axial displacements of the plug, for example caused by doming of the cap base under pressure from inside the container, without loss of sealing effectiveness.
[0029]The container closure in the assembly according to the present invention further comprises a circumferential sealing skirt. The sealing skirt is separate and radially spaced from the threaded cap skirt that engages the thread on the outside of the container neck. Suitably, the sealing skirt is substantially tubular, and projects downwardly from the base of the cap intermediate the cap skirt and the sealing plug. The sealing skirt is preferably substantially concentric with the threaded skirt and the sealing plug, and coaxial with the longitudinal axis of the cap. The height of the sealing skirt is suitably from about 1 mm to about 5 mm, for example about 1.5 mm to about 2.5 mm. The height of the sealing skirt in certain embodiments (measured from the inside surface of the cap adjacent to the inside surface of the sealing skirt) is at least about 50%, for example at least about 75% of the height of the sealing plug. The sealing skirt is normally molded integrally with the base of the cap. The mean thickness of the tubular wall of the sealing skirt is suitably from about 0.5 mm to about 2 mm, for example about 0.7 mm to about 1.2 mm. This gives the sealing skirt the right degree of resilience and strength for the desired sealing function.
Problems solved by technology
The present inventors have found that the above sealing arrangements in which a portion of the cap abuts directly against the top of the container lip present a problem, which is that the application of an axial force on the cap to displace it further towards the neck from the fully closed and sealing position results in permanent deformation and damage to the cap and impaired subsequent sealing.
It goes without saying that the prior art closure assemblies currently in use, as described above, do not have this property, as they all require direct abutment between the top of the container lip and the cap at the sealing position that blocks further axial movement of the cap towards the neck under axial force and / or results in permanent, plastic deformation of the cap under the axial force that impairs the sealing properties of the assembly both during and after the axial force is applied.
Method used
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[0072]Referring to FIGS. 1 and 2, this embodiment is a container closure assembly especially adapted for a carbonated beverage container. Many features of this assembly resemble those of the assembly described and claimed in our International Patent Applications WO95 / 05322 and WO97 / 21602 and WO99 / 19228. However, it is important to note that the threads on the closure and the neck are reversed in the present invention relative to the closure assemblies described in those applications. That is to say, the earlier patent specifications describe in detail assemblies having short thread segments in the closure skirt and longer thread segments on the neck, whereas the present invention provides only short thread segments on the neck and longer thread segments on the closure skirt.
[0073]The assembly according to this embodiment includes a container neck 10 of a container for carbonated beverages, and a closure 12. Both the container neck and the closure are formed from plastics material, b...
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A container closure assembly includes a container neck having an opening at one end, a lip extending around the opening; a cap for said neck, the cap having a base portion and a threaded skirt; a screw thread on the neck; a screw thread on an inner surface of the threaded skirt of the cap; the screw threads enabling a user to secure, remove and resecure the cap into a sealing position on the neck; an olive sealing plug extending from the cap inside and substantially concentric with said threaded skirt portion of the cap, the sealing plug forming a seal against an inside surface of the neck; and a sealing skirt extending from said base of the cap intermediate said sealing plug and said threaded skirt portion of the cap and concentric with said sealing plug and said threaded skirt portion of the cap, wherein said cap can be displaced towards said neck from said sealing position by application of an axial force without rotation of the cap on the neck and substantially without plastic deformation of the cap.
Description
BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to improved seals for container closure assemblies. The invention is especially applicable to the sealing of containers in substantially gas-tight and liquid-tight fashion, such as the sealing of carbonated and non-carbonated beverage containers.[0003]It is well known to provide beverage containers of glass, paper, card, metal or plastic having a screw top that can be resecured on the bottle neck. It is desirable to provide such containers with a screw top cap assembly that provides an airtight and liquid-tight seal to retain the quality of the beverage both during initial transport and storage, and after partial consumption of the contents when the cap has been resecured onto the container neck.[0004]The present invention relates to improved seals for container closure assemblies. The invention is especially applicable to the sealing of containers in substantially gas-tight and liquid-tigh...
Claims
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Login to View More IPC IPC(8): B65D41/04
CPCB65D41/0421B65D41/0471B65D2101/003B65D1/0246B65D2401/20
InventorKING, ROGER MILNER
OwnerBEESON & SONS