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Threaded closure with internal ribs

Threaded closure with internal ribs description/claims

The present invention relates generally to molded plastic closures used with associated containers such as for packaging beverages, and more particularly to an internally threaded plastic closure having an array of axially extending internal ribs which can cooperate with an associated container to facilitate venting of gas pressure from within the container during closure removal. The internal ribs can also desirably be configured to provide the necessary dimensioned characteristics while minimizing the quantity of polymeric material from which each closure is formed in both venting and non-venting closure applications.

Molded plastic closures which can be threadably applied to associated containers for packaging products such as carbonated and non-carbonated beverages have met with widespread success in the marketplace. Closures of this nature can be efficiently formed by compression molding and injection molding techniques, with the closures configured for tamper-evidence as may be required for some applications. These types of closures can provide highly effective sealing performance, even when used with containers having pressurized contents, with the threaded nature of the closures facilitating convenient removal, and re-application, by consumers. U.S. Pat. No. 4,938,370, No. 5,004,112, No. 5,167,335, No. 5,205,426, and No. 6,557,714, the disclosures all of which are hereby incorporated by reference, illustrate molded plastic closure constructions, and associated packages.

As will be appreciated, packaging of carbonated beverages and like products requires closure sealing performance which maintains the elevated level of gas pressure within the associated container. However, during closure removal, it is desired for this gas pressure within the associated container to be released prior to disengagement of the closure threads from the external thread formation of the associated container. To this end, the provision of axially extending vent grooves in both containers and closures is known in the art. The vent grooves typically traverse and interrupt the closure or container threads, thus providing one or more flow paths for gas pressure to be released from within the container after the sealing interface between the closure and container is broken, but prior to disengagement of the respective thread formations. In current commercial embodiments of packaging for carbonated beverages, both the container and the closure typically define at least several axially extending vent grooves traversing the respective thread formations, with maximum venting performance typically occurring during alignment of the closure and container vent grooves.

In a typical closure construction including axially extending vent grooves, the vent grooves not only traverse the closure thread formation, but typically extend partially into the side wall of the closure to provide flow paths which permit gas flow around the outer periphery of the associated container thread formation. However, experience has shown that the regions at which such axially extending vent grooves are formed in the side wall can undesirably be prone to cracking or other failure, thus detracting from the structural integrity and performance characteristics of the closure.

The present invention is directed to an improved configuration for an internally threaded plastic closure which can be configured to facilitate gas venting, and which at the same time permits formation of the venting and non-venting closures with a relatively reduced quantity of polymeric material, while permitting the closures to exhibit the necessary dimensional characteristics so that the closures can be used in conjunction with conventionally configured containers, and high-speed capping equipment.

The present invention is directed to an internally threaded plastic closure having a plurality of circumferentially spaced, axially extending vent grooves which intersect the thread formation on the inside surface of a skirt portion of the closure. By this arrangement, a plurality of vent paths are formed between adjacent ones of the axially extending internal ribs, with each flow path extending outwardly of the external thread formation of the associated container. Because the vent paths are provided without the formation of vent grooves or the like in the sidewall of the closure, problems associated with closure failure at the vent grooves are desirably avoided. Additionally, the provision of an array of internal axially extending ribs permits fitting both venting and non-venting closures to conventionally dimensioned containers, while permitting the side wall of the closure to be of a relatively reduced thickness for desirably reducing the quantity of polymeric material from which each closure is formed.

In accordance with the illustrated embodiment, the present closure comprises a molded plastic closure cap formed from polymeric material, such as polypropylene, polyethylene, copolymers, etc. The closure cap includes a top wall portion, and an annular skirt portion depending from the top wall portion. The closure includes a sealing portion for sealingly engaging an associated container, which can be provided in the form of at least one annular sealing element depending from the inside surface of the top wall portion of the closure cap, or in the form of a separate sealing liner positioned within the closure cap adjacent to the top wall portion.

In order to facilitate threaded application of the closure to an associated container, the skirt portion of the closure cap includes at least one helical, internal thread formation for cooperating engagement with an external thread formation on the associated container.

In accordance with the present invention, the skirt portion of the closure cap further includes a plurality of circumferentially spaced, axially extending internal ribs, with at least some of said axially extending ribs intersecting the internal thread formation of the closure cap. By this arrangement, vent passages are defined between adjacent ones of the internal ribs to facilitate venting of gas pressure from within an associated container during closure removal. Additionally, the provision of the internal ribs permits the present closure to be fitted to a conventionally dimensioned container, while permitting the side wall of the closure cap to be of a relatively reduced thickness for reducing the weight of the closure cap.

For non-venting closures for use on containers having non-carbonated contents, the internal thread formation of the closure cap can extend continuously about an inside surface of the skirt portion. In illustrated embodiments, the internal thread formation is discontinuous to define vent paths, and comprises a plurality of thread segments helically arranged around the inside surface of the skirt portion. In one of these embodiments, the discontinuous thread formation includes a plurality of connector elements respectively extending between adjacent ones of the thread segments on the inside surface of the skirt portion. The connector elements each have a radial dimension less than a radial dimension of the thread segments, such that the venting capacity of the closure is maintained, while providing closure threads which are relatively more robust.

Other features and advantages of the present invention will become readily apparent from the following detailed description, the accompanying drawings, and the appended claims.

FIG. 1 is a perspective view of an internally threaded plastic closure having an array of internal ribs in accordance with the present invention;

FIG. 2 is a perspective view of the neck portion of a container to which the present closure can be applied;

FIG. 3 is an alternate embodiment of the present internally threaded closure; and

FIG. 4 is a further alternate embodiment of the present internally threaded closure.

• Provisional Patent
• Utility Patent

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