Composite closure with enhanced sealing

Abstract

A composite closure includes a plastic outer closure cap, and an inner sealing liner positioned adjacent to an inside surface of a top wall portion of the outer cap. In order to enhance sealing integrity with an associated container, the liner is configured to include inward and outwardly facing sealing surfaces, with the provision of an annular sealing bead providing a top/side seal with an associated container, and an annular sealing plug fitting within the mouth of an associated container for providing an inside seal. The closure construction has been found to maintain sealing integrity with an associated container when the closure and container package is subjected to relatively high temperatures.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to plastic closures for use with an associated container, and more particularly to a composite plastic closure, including an outer closure cap and an inner sealing liner, wherein the sealing liner defines cooperating outside and inside the sealing surfaces for enhanced sealing with the associated container.

BACKGROUND OF THE INVENTION

[0002] Plastic closures for use on containers such as for carbonated beverages and the like have met with widespread success in the marketplace. One type of composite closure construction includes a compression molded outer plastic cap or shell, and an inner sealing liner which can be efficiently formed by compression molding within the outer closure cap. The outer closure cap can be formed from polypropylene or like polymeric material for the desired strength and durability, while the inner sealing liner may be formed from a softer polymeric material, such as ethylene vinyl acetate (EVA). This type of closure can be formed with a tamper-indicating pilfer band to assure the quality of the container's contents for a consumer. U.S. Pat. No. 4,378,893, U.S. Pat. No. 4,407,422, U.S. Pat. No. 4,418,828, U.S. Pat. No. 4,497,765, and U.S. Pat. No. 4,978,017, all hereby incorporated by reference, illustrate these types of compression molded composite closures, and methods of formation.

[0003] Heretofore, these types of composite closures have been very effective for use on carbonated beverages by virtue of the formation of a so-called top/side seal between the sealing liner of the closure and the finish of an associated container. For such applications, the sealing liner is configured to define a downwardly facing top seal surface, and includes an annular sealing bead portion which defines a generally inwardly facing sealing surface at the periphery of the top sealing surface. The downwardly facing and inwardly facing sealing surfaces cooperate with the associated container to form a top/side seal generally at the top and top outside corner portions of the associated container. Even if the closure exhibits outward deformation of its top wall portion, a phenomenon known as “doming” which can result from cold flow deformation or “creep” of the plastic material under the influence of gas pressure within the container, the sealing integrity of the closure is maintained.

[0004] Sealing of this outside, top corner of the container finish typically provides the requisite sealing integrity for the container to maintain the quality of the container contents. However, under certain conditions, the sealing integrity of such a top/side seal closure can be impaired. If the closure and container package are subjected to relatively high temperatures, such as an excess of 42° C., for extended periods of time, and is then subjected to top loading, the sealing between the closure and the container can be impaired. A similar effect can occur if the closure is pierced with a so-called Zham Nagel needle, as is used for ascertaining the level of carbon dioxide carbonation within the package.

[0005] In view of this, it is desirable to provide a closure construction, including a sealing liner which is configured to effectively seal carbonated soft drink packages after the packages are subjected to temperatures on the order of 42° C. for as long as fourteen (14) days, and still maintain sealing integrity if subjected to top loading conditions, and/or piercing with Zham Nagel needles, as are typically employed for assessing the level of carbonation in the package. A closure system that is able to maintain sealing integrity under such high temperature conditions will act to provide better sealing performance in those geographical regions which typically exhibit high temperatures, such as in southern Europe or in the southwestern United States.

[0006] While enhanced sealing performance under such high temperature conditions is desirable, a closure construction must be configured so as to facilitate high-speed application with automated capping equipment, while avoiding any deterioration of the sealing liner and the closure. In particular, it is important that a closure construction avoid “stringing” which can result during high-speed closure application, that is, the shearing of small, elongated pieces of the liner material from the liner by the bottle finish during application of the closure at high speed.

SUMMARY OF THE INVENTION

[0007] A composite closure configured in accordance with the present invention includes an outer closure cap, and a sealing liner positioned adjacent an inside surface of a top wall portion of the closure cap. Notably, the sealing liner is configured to define cooperating inwardly and outwardly facing sealing surfaces by the provision of an annular sealing plug element which is configured to extend into the bottle finish of the mouth of an associated container. By this arrangement, not only is the desired top/side seal formed at the upper outside corner of the container finish, but additionally, an inside seal is formed by the sealing plug. The configuration of the closure has been found to desirably enhance the high-temperature sealing characteristics of the closure, with the sealing integrity of the closure maintained under high-temperature conditions such as described above, and attendant to carbonation testing entailing piercing of the closure by a Zham Nagel needle.

[0008] In accordance with the illustrated embodiment, the present composite closure includes an outer closure cap having a top wall portion, and an annular, depending skirt portion. The skirt portion includes an internal thread formation for securement of the closure to an associated container, and may include a tamper-indicating pilfer band formed integrally with the closure skirt.

[0009] The closure cap includes an annular shoulder extending inwardly of the skirt portion in spaced relationship to the top wall portion. In the illustrated embodiment, the annular shoulder is configured generally as a sealing lip, which defines an annular recess positioned between the annular shoulder and the top wall portion of the closure.

[0010] The present composite closure further includes a sealing liner positioned adjacent the inside surface of the top wall portion of the outer closure cap. The sealing liner includes an annular outside sealing bead portion positioned adjacent to the annular shoulder, with the sealing bead portion extending into the annular recess defined between the shoulder and the top wall portion.

[0011] The sealing liner further includes an annular inside sealing plug spaced inwardly from the outside sealing bead portion of the liner. The sealing plug defines with the annular bead portion an annular recess for receiving the mouth of an associated container.

[0012] In order to facilitate high-speed application, the outer sealing portion of the liner includes an outwardly, downwardly tapering guide surface adjacent the annular shoulder of the closure cap. The outside sealing bead portion further includes an outside sealing surface extending from the guide surface into the annular recess of the liner.

[0013] The sealing plug of the closure includes an inwardly, downwardly tapering guide surface, and an adjacent inside sealing surface extending into the annular recess. The guide surfaces cooperate to facilitate fitment of the closure to a container, and disposition of the container in the annular recess between the outside and inside sealing surfaces.

[0014] In the preferred form, the guide surface and sealing surface of the sealing plug are arranged at an obtuse angle, with the sealing surface of the sealing plug preferably vertically oriented. The guide surface of the sealing plug extends at an angle of 15°, plus or minus 10°, relative to the horizontal.

[0015] In the preferred form, the sealing surfaces of the annular sealing bead portion and sealing plug are arranged in converging relationship in the annular recess of the liner. The liner includes a downwardly facing, top sealing surface extending between the sealing surface of the sealing bead portion, and the sealing surface of the sealing plug. The downwardly facing top sealing surface is preferably perpendicular to the sealing surface of the plug.

[0016] In accordance with the illustrated embodiment, the sealing liner defines a radius between the sealing surface of the bead portion and the top sealing surface of the liner of at least about 0.005 inches. The sealing plug of the liner defines a radius between the guide and sealing surfaces thereof of at least about 0.010 inches.

[0017] 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

[0018] FIG. 1 is a cross-sectional view of a composite closure embodying the principles of the present invention;

[0019] FIG. 2 is a relatively enlarged, fragmentary view further illustrating the composite closure of FIG. 1.

DETAILED DESCRIPTION

[0020] While the present invention is susceptible of embodiment in various forms, there is shown in the drawings, and will hereinafter be described, a presently preferred embodiment, 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.

[0021] With reference now to the drawings, therein is illustrated a composite closure 10 embodying the principles of the present invention. Composite closure 10 includes a plastic outer closure cap 12, preferably formed from polypropylene or a like polymeric material. 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 preferred form, the skirt portion 16 includes an internal thread formation 18 for cooperating engagement with a like thread formation on an associated container. If the closure 10 is to be configured for tamper-indication, the closure includes a pilfer band 20 at least partially detachably connected to the skirt portion 16.

[0022] In order to provide the desired sealing performance for use on a container having carbonated or otherwise pressurized contents, composite closure 10 includes a sealing liner 22 positioned adjacent an inside surface of top wall portion 14. Sealing liner 22 is preferably formed by compression molding within the outer closure cap 12, and to this end, the outer closure cap 12 includes an annular shoulder 24 extending inwardly of the skirt portion 16. Annular shoulder 24 provides a surface against which a sleeve of a liner-forming tool is seated during formation of sealing liner 22 attendant to compression molding of the liner. In the illustrated embodiment, annular shoulder 24 is provided in the form of an annular seal lip which defines an annular recess 26 between the shoulder and the top wall portion 14 of the outer closure cap.

[0023] In accordance with the present invention, the sealing liner 22 of closure 10 is configured to provide cooperating outside and inside seals with an associated container. To this end, the sealing liner includes an annular, outside sealing bead portion 28, which extends into annular recess 26. Sealing bead portion 28 is positioned adjacent annular shoulder 24, and is configured to facilitate high-speed closure application, and effective closure sealing. To this end, the annular sealing bead portion 28 includes an outwardly, downwardly tapering guide surface 30 adjacent shoulder 24, and a generally inwardly facing, outside sealing surface 32 which extends from the guide surface 30.

[0024] The desired sealing integrity between the closure 10 and the associated container is further enhanced by the provision of an annular sealing plug 34 which depends from a central portion 36 of the liner 22. The sealing plug 34 is spaced inwardly from the outside sealing bead portion 28, and defines therewith an annular recess 38 for receiving the mouth portion of the associated container.

[0025] The sealing plug 34 is configured to extend into the mouth of the associated container C, and sealing engage the inside and top/inside corner of the container finish, for providing sealing in cooperation with the top/side seal provided by sealing bead portion 28. In the preferred embodiment, the sealing plug includes an inwardly, downwardly tapering guide surface 40, an adjacent inside sealing surface 42 which extends into the annular recess 38, and a radiuses transition region 43 extending therebetween.

[0026] In the preferred embodiment, the guide surface 40 and the sealing surface 42 of sealing plug 34 are arranged at an obtuse angle to each other, with the sealing surface 42 preferably vertically oriented, and the guide surface 40 arranged at an angle of 15°, plus or minus 10°, relative to the horizontal. To facilitate application of the closure to an associated container, the sealing plug 34 defines a radius at transition region 43 between the guide and sealing surfaces 40, 42 of at least about 0.010 inches.

[0027] The sealing liner 22 defines a downwardly facing top sealing surface 44 which extends between the sealing surface 32 of the bead portion 28, and the sealing portion 42 of the sealing plug 34. Top sealing surface 44 is preferably perpendicular to the vertically oriented sealing surface 42 of the plug 34. In contrast, the top sealing surface 44 is arranged at an obtuse angle to sealing surface 32, with the sealing surfaces 32, 44 arranged in converging relationship in the annular recess 38. Sealing liner 22 defines a radius between the sealing surface 32 of the annular sealing bead 28, and the top sealing surface 44 of at least about 0.005 inches.

[0028] In a current embodiment of the present composite closure, suited for fitment on a standardized container finish, the sealing plug 34 has been sized with an outside diameter of 0.885 inches, with a nominal inside diameter at the sealing surface 32 of annular sealing bead 28 of 0.964 inches. By the illustrated arrangement, guide surfaces 30, 40 of the sealing liner 22 desirably act to guide and seat a container finish within the annular groove 38 of the liner, with the upwardly converging outside and inside sealing surfaces 32 and 42 further facilitating seating of the closure within the annular recess 38 until it engages top sealing surface 44. In the preferred form, sealing plug 34 has a radial dimension of about 0.033 inches, and a maximum vertical dimension, from central portion 36, of 0.042 inches. The central portion 36 of the sealing liner 22 has a nominal thickness of 0.012 inches, with the liner thickness at top sealing surface 44 being 0.016 inches.

[0029] The above-described preferred dimensioning of the sealing liner 22 acts to desirably provide the enhanced sealing characteristics for the present composite closure, while at the same time minimizing use of the relatively expensive material from which the sealing liner is formed. The described dimensioning of the sealing plug 34 facilitates high-speed closure application, by providing the desired sealing with the associated container, but while exhibiting sufficient flexibility to avoid interference with the associated container during closure application. The above-described dimensioning and angular relationships have been found to provide the desired penetration of the container finish into the annular recess 38, thus providing a greater axial seal length for sealing engagement of the liner with the closure, with the illustrated configuration exhibiting less sensitivity to static torque and variations in closure application speed. The arrangement desirably avoids “stringing” or other deterioration of the liner attendant to high-speed closure application.

[0030] From the foregoing, 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 embodiment disclosed 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 composite closure for a container, comprising: an outer closure cap having a top wall portion and an annular skirt portion, said closure cap including an annular shoulder extending inwardly of said skirt portion in spaced relationship to said top wall portion; and a sealing liner positioned adjacent an inside surface of said top wall portion, said sealing liner including an annular outside sealing portion positioned adjacent to said annular shoulder, and an annular inside sealing plug spaced inwardly from said outside sealing portion, and defining therewith an annular recess for receiving said container, said outside sealing portion including an outwardly, downwardly tapering guide surface adjacent said shoulder, and an outside sealing surface extending from said guide surface into said annular recess, and a transition region extending therebetween said sealing plug including an inwardly, downwardly tapering guide surface, an adjacent inside sealing surface extending into said annular recess, said guide surfaces facilitating fitment of said closure to a container and disposition of said container in said annular recess between said outside and inside sealing surfaces.

2. An composite closure in accordance with claim 1, wherein: said guide surface and said sealing surface of said sealing plug are arranged at an obtuse angle to each other.

3. A composite closure in accordance with claim 2, wherein: said sealing surface of said sealing plug is vertically oriented.

4. A composite closure in accordance with claim 1, wherein: said sealing surfaces are arranged in converging relationship in said angular recess.

5. A composite closure in accordance with claim 3, wherein: said sealing liner includes a downwardly facing top sealing surface extending between the sealing surface of said outside sealing portion and the sealing surface of said sealing plug, said top sealing surface being perpendicular to said sealing surface of said plug.

6. A composite closure in accordance with claim 1, wherein: said outer closure cap defines an annular recess positioned between said annular shoulder and said top wall portion into which said annular sealing portion of said liner extends.

7. A composite closure for a container, comprising: an outer closure cap having a top wall portion and an annular skirt portion, said closure cap including an annular shoulder extending inwardly of said skirt portion in spaced relationship to said top wall portion; and a disc-shaped sealing liner positioned adjacent to an inside surface of said top wall portion, said sealing liner including an annular outside sealing bead portion positioned adjacent said annular shoulder, and an annular inside sealing plug spaced inwardly from said outside sealing bead portion, and defining therewith an annular recess for receiving said container, said sealing bead portion including an outwardly, downwardly tapering guide surface adjacent said shoulder, and an outside sealing surface extending from said guide surface into said annular recess, said plug including an inwardly, downwardly tapering guide surface and an adjacent inside sealing surface extending into said annular recess arranged vertically and at an obtuse angle to said plug sealing surface, said sealing surfaces being arranged in converging relationship in said annular recess, and extending to a downwardly facing top sealing surface which is perpendicular to said vertical sealing surface of said sealing plug.

8. A composite closure in accordance with claim 7, wherein: said outer closure cap defines an annular recess positioned between said annular shoulder and said top wall portion into which said annular sealing bead portion of said liner extends.

9. A composite closure in accordance with claim 8, wherein: said sealing liner defines a radius between said sealing surface of said bead portion and said top sealing surfaces of at least about 0.005 inches.

10. A composite closure in accordance with claim 8, wherein: said sealing plug defines a radius between the guide and sealing surfaces thereof of at least about 0.010 inches.

11. A composite closure in accordance with claim 8, wherein: said guide surface of said sealing plug extends at an angle of 15°, ±10° relative to the horizontal.