US20090045158A1

US20090045158A1 - Threaded closure with internal ribs

Info

Publication number: US20090045158A1
Application number: US11/891,907
Authority: US
Inventors: Jordi Lluch Suriol
Original assignee: Alcoa Closure Systems International Inc
Current assignee: Closure Systems International Inc
Priority date: 2007-08-14
Filing date: 2007-08-14
Publication date: 2009-02-19
Also published as: BRPI0815420A2; AU2008287506A1; EP2197758A4; WO2009023102A1; CN101801805A; RU2010109399A; EP2197758A1; JP2010536665A; AU2008287506B2; MX2010001635A; ZA201001065B; CA2695987A1

Abstract

An internally threaded plastic closure in accordance with the present invention includes an array of axially extending, circumferentially spaced internal ribs which intersect the internal thread formation of the closure. By this arrangement, vent passages are defined between adjacent ones of the internal ribs, thus providing the closure with desirable gas venting characteristics, while avoiding the provision of vent grooves extending into the inside surface of the closure side wall, which can undesirably impair the strength of the side wall. By the present construction, the amount of polymeric material from which the closure is formed can be desirably reduced, while maintaining the desired dimensional characteristics of the closure, to facilitate use with existing containers and high-speed capping equipment.

Description

BACKGROUND OF THE INVENTION

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.

TECHNICAL FIELD

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.

SUMMARY OF THE INVENTION

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.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

DETAILED DESCRIPTION

While the present invention is susceptible of embodiment in various forms, there is shown in the drawings, and will hereinafter be described, presently preferred embodiments, with the understanding that the present disclosure is to be considered as an exemplification of the invention, and is not intended to limit the invention to the specific embodiment illustrated.
With reference first to FIG. 1, therein is illustrated a closure 10 embodying the principles of the present invention. Closure 10 includes a molded plastic closure cap 12 formed from polymeric material, such as polypropylene, polyethylene, copolymers, and the like, as are known in the art.
The closure cap 12 includes a top wall portion 14, and an annular skirt portion 16 depending from the top wall portion 14. In the illustrated embodiment, closure 10 is configured for tamper-evidence, and to this end, the closure includes an annular, tamper-evident band 18 depending from skirt portion 16, and at least partially frangibly connected to the skirt portion. Tamper-evident band 18 may include one or more suitable engaging elements 20 for cooperative engagement with an associated container, whereby during closure removal the tamper-evident band is at least partially detached from the skirt portion 16 to provide readily visually discernible evidence that the closure has been partially or completely removed from an associated container. Tamper-evident band 18 can be frangibly connected to the skirt portion 16 such as by a plurality of circumferentially spaced, frangible bridges 22 which detachably connect the tamper-evident band to the skirt portion. As illustrated in FIG. 2, container C may include an annular locking ring L, or like element, for cooperation with the engaging elements 20 of the tamper-evident band 18 for effecting tamper-indication.
Threaded application of the closure 10 to an associated container, such as container C illustrated in FIG. 2, is facilitated by the provision of at least one helical thread formation 24 provided on the inside surface of skirt portion 16 of closure cap 12. The thread formation 24 is configured for cooperative, threaded engagement with an external thread formation T on container C, whereby relative rotation of the closure with respect to the container effects application and removal of the closure. In this illustrated embodiment, the thread formation 24 is shown as discontinuous, and comprising a plurality of cooperating thread segments to define a plurality of vent paths. However, for use on containers having non-carbonated contents for which gas venting may not be required, the thread formation 24 may be continuous, such as illustrated in phantom line at 24′.
In order to provide the desired sealing cooperation between the closure 10 and container C, the closure includes a sealing portion for sealingly engaging the associated container. In the embodiment of FIG. 1, the sealing portion of the closure 10 is provided integrally with the closure cap 12, such as in the form of an annular sealing element 26 depending from an inside surface of the top wall portion 14 of the closure cap. Sealing element 26 can be configured to fit generally within the open mouth of the associated container to provide a so-called plug seal. As will be recognized by those familiar with the art, the closure 10 may include one or more additional sealing features, and may be provided with a separate, typically disc-shaped sealing liner positioned within the closure cap adjacent the top wall portion 14.
In order to facilitate release of gas pressure from within container C during removal of closure 10 therefrom, the external thread formation T of the container defines at least one axially extending vent groove G intersecting and interrupting the external thread formation T of the container. The provision of the vent grooves G permits gas pressure from within the container to flow generally between the inner peripheral edge of the closure thread formation 24, and the exterior of the container finish after the sealing portion of the closure has been moved out of sealing cooperation with the container, during closure removal.
In order to further facilitate release of gas pressure from within the container, and in accordance with the present invention, closure cap 12 of closure 10 includes an array of internal ribs 28 positioned in circumferentially spaced relationship on the inside surface of skirt portion 16, with at least some of the ribs 28 intersecting the internal thread formation 24. By the provision of internal ribs 28, a plurality of gas passages are defined extending along the inside surface of skirt portion 16, with each of the gas passages facilitating flow of gas outwardly of the outer periphery of the external thread T of container C. Each of the internal ribs 28 preferably has a radial dimension less than that of the associated thread formation 24 to provide the desired plurality of vent passages. By way of example, in a current embodiment having twenty-four (24) of the internal ribs 28, each rib has a radial dimension of 0.008 inches, while the associated thread formation has a radial dimension of 0.040 inches.
As will be appreciated, the configuration of the present closure, including the provision of internal ribs 28, desirably configures the closure to provide the desired venting performance, while avoiding the provision of vent grooves which extend into the inside surface of sidewall 16, as in previous constructions. Any weakening of the closure sidewall associated with these types of previous vent grooves is thus desirably avoided.
Additionally, the provision of the internal ribs 28 desirably permits the closure 10 to be formed from less polymeric material, desirably saving weight and cost. In particular, the thickness of the sidewall 16 of the closure cap 12 can be relatively reduced, while maintaining the conventional outside dimension of the closure to facilitate application with existing camping equipment. The internal ribs 28 can be dimensioned to provide the desired cooperation with the external thread formation T of the associated container, thus ensuring that each closure can be properly fitted to an associated container.
A further benefit of the present invention relates to cooperation of the internal ribs 28 with the external thread formation T of the associated container, particularly at the vent grooves G defined by the container. Heretofore, the provision of rotation-inhibiting projections, sometimes referred to as “speed bumps”, on the inside surface of a closure is intended to cooperate with the thread formation of the associated container to inhibit free rotation of the closure on the container during closure removal. By providing predetermined interference between such projections and the container thread formation, closure removal is effected over a time span which facilitates release of gas pressure from within the associated container prior to disengagement of the respective thread formations on the closure and container.
By the present construction, during closure removal the internal ribs 28 are substantially continuously contacting the external thread formation T of the container, particularly at the vent grooves G, to create the desired resistance to free spin. However, notwithstanding this desired resistance to free rotation, experience has shown that the present closure remains desirably convenient to remove, facilitating convenient use by consumers. By way of example, a conventional closure may include two rotation-inhibiting projections, with a standard container finish having 4 vent grooves G. Thus, during each rotation of the closure relative to the container, there are a total of 8 interfering engagements of a projection with a vent groove (i.e., 2 projections times 4 vent grooves). In contrast, the illustrated embodiment of the present closure 10 includes twenty (20) of the circumferentially spaced internal ribs 28. Thus, when the present closure is fitted to a conventional container finish having four of the vent grooves G, each turn of the closure relative to the container creates 80 interfering engagements, which 76 is tactilely perceived as smoother during closure removal. Thus, the desired resistance to free spin of the closure on the container can be achieved, while facilitating convenient consumer use.
As shown in phantom line at 24′ in the embodiment of the present closure illustrated in FIG. 1, internal thread formation 24 can extend continuously, without interruption, about the inside surface of the closure skirt portion 16. The embodiments of the present closure illustrated in FIGS. 3 and 4 each include discontinuous internal thread formations, each formed by a plurality of thread segments helically arranged about the inside surface of the skirt portion of the closure.
In the embodiment of FIG. 3, a closure 110 includes elements corresponding to those of the previous embodiment designated by like reference numerals in the 100-series. Closure 110 includes a discontinuous thread formation 124 comprising helically arranged thread segments which are spaced from each other, and are otherwise unconnected. Closure 110 includes a tamper-evident band 118 having projections 120 which can be configured in accordance with the teachings of U.S. Pat. No. 5,242,068, hereby incorporated by reference. The closure can be formed with a separate sealing liner 27.
In contrast, in the embodiment of FIG. 4, thread formation 24 includes thread segments which are spaced from each other, but with connector elements 25 respectively extending between adjacent ones of the thread segments. The connector elements each have a radial dimension less than the radial dimension of the associated thread segments, with the connector elements acting to provide a more robust internal thread formation, which can desirably enhance the hoop strength of the skirt portion. As will be appreciated, the provision of the connector elements 25 acts to maintain the venting performance achieved by the provision of the multiple vent passages defined by the internal ribs 28.
Notwithstanding the relatively reduced side wall thickness that can be achieved in accordance with the present invention, the provision of internal ribs desirably acts to guide the present closure onto the neck portion of the associated container during high-speed application with automated capping equipment. As will be appreciated, contact points of support are provided where each of the internal ribs engages the outer periphery of the external thread formation T of the container C, as opposed to engagement of the container thread formation along the complete inside surface of the skirt portion. Notwithstanding, the practical result of the present invention is substantially the same for purposes of high-speed, automated application. The internal ribs desirably act to guide the closure during application travel, offering a better level of adjusting. Ordinarily, designers must keep some clearance between the closure and the container neck to avoid jamming in the system. The internal ribs offer the advantage of working with substantially zero clearance, since even with some interference, the ribs can be easily deformed without blocking the system. This offers the possibility to better fit and adjust onto the container neck finish, despite typical tolerance issues. The closure is desirably centered on the associated container, and desirably resists cocking during high-speed operation, which can undesirably result in improper application of a closure to an associated container. As will be recognized by those familiar with the art, any reduction in the quantity of material from which each closure is formed can very desirably result in substantial cost savings.
From the foregoing, it will be observed that numerous modifications and variations can be effected without departing from the true spirit and scope of the novel concept of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated herein is intended or should be inferred. The disclosure is intended to cover, by the appended claims, all such modifications as fall within the scope of the claims.

Claims

1. A closure for a container, comprising:

a molded plastic closure cap formed from polymeric material, said closure cap including a top wall portion, and an annular skirt portion depending from said top wall portion,

said closure including a sealing portion for sealingly engaging an associated container,

said skirt portion including at least one helical, internal thread formation for cooperating engagement with a thread formation on the associated container,

said skirt portion further including a plurality of circumferentially spaced, axially extending ribs, at least some of said axially extending ribs intersecting said internal thread formation.

2. A closure for a container in accordance with claim 1, wherein:

said internal thread formation extends continuously about an inside surface of said skirt portion.

3. A closure for a container in accordance with claim 1, wherein:

said internal thread formation is discontinuous, and comprises a plurality of thread segments helically arranged about an inside surface of said skirt portion.

4. A closure for a container in accordance with claim 4, wherein:

said discontinuous thread formation includes a plurality of connector elements respectively extending between adjacent ones of said thread segments on the inside surface of said skirt portion, said connector elements each having a radial dimension less than a radial dimension of said thread segments.

5. A closure for a container in accordance with claim 1, wherein:

said sealing portion of closure comprising at least one annular sealing element depending from an inside surface of said top wall portion of said closure cap.

6. A closure for a container in accordance with claim 1, wherein:

said sealing portion of said closure comprises a sealing liner positioned within said closure cap adjacent said top wall portion.

7. A closure for a container in accordance with claim 1, including:

an annular, tamper-evident band depending from said skirt portion and at least partially, frangibly connected thereto.

8. A closure and container package, comprising;

a container have a neck portion having an external thread formation; and

a closure configured to be removably applied to said container,

said closure comprising a molded plastic closure cap formed from polymeric material, said closure cap including a top wall portion, and an annular skirt portion depending from said top wall portion,

said closure including a sealing portion for sealingly engaging said container,

said skirt portion including at least one helical, internal thread formation for cooperating engagement with the external thread formation on said container,

said skirt portion further including a plurality of circumferentially spaced, axially extending ribs, at least some of said axially extending ribs intersecting said internal thread formation, and defining a plurality of vent passages between adjacent ones of said axially extending ribs.

9. A closure and container package in accordance with claim 8, wherein:

said container defines at least one axially extending vent groove intersecting said external thread formation.

10. A closure and container package in accordance with claim 8, wherein:

said internal thread formation of said closure is discontinuous, and comprises a plurality of thread segments helically arranged about an inside surface of said skirt portion.

11. A closure and container package in accordance with claim 10, wherein:

12. A closure and container package in accordance with claim 10, wherein: