Plastic closure, closure and container package, and method of manufacture

Abstract

A method of making a closure having an end panel and a sealing liner on one face of the end panel includes providing an injection mold having at least first and second mold elements, at least one of which is movable with respect to the other. The first and second mold elements are positioned to form a first mold cavity, and the end panel is injection molded within the first mold cavity. At least one of the first and second mold elements then is moved to form a second mold cavity in which a face of the end panel forms at least one mold cavity wall, and the sealing liner is injection molded onto the face of the end panel. The end panel and liner are then removed from the second mold cavity. The liner/disk subassembly thus is provided more easily and economically than if the liner were compression molded in situ onto the undersurface of a separately formed disk. The closure preferably is a two-piece closure, and the method preferably includes the step of assembling the end panel to a separately formed closure shell.

Description

The present disclosure is directed to plastic closures for beverage, food, juice, pharmaceutical and like applications, and more particularly to a closure, package and method of manufacture that are particularly well suited for high-temperature (e.g., pasteurization, hot-fill and retort) applications.

BACKGROUND AND SUMMARY OF THE INVENTIONS

It heretofore has been proposed to provide a plastic closure for a container, which includes a plastic cap or shell with an interior liner for sealing engagement with a sealing surface of the container finish. For example, U.S. Pat. No. 4,984,703 discloses a plastic closure that comprises a shell having a base wall with a peripheral skirt and at least one internal thread or bead for securing the closure to a container finish, and a sealing liner compression molded in situ on the interior of the shell base wall. U.S. Pat. No. 5,451,360 discloses a method and apparatus for compression molding the liner in situ within the closure shell. It also has been proposed to provide plastic resin barrier materials within the sealing liner for resisting transmission of gases (e.g., carbon dioxide and oxygen), water vapor and/or flavorants through the liner. For example, U.S. Pat. No. 6,371,318 discloses a plastic closure and method of manufacture in which the liner is compression molded in situ on the interior surface of the closure base wall, and includes a multiplicity of alternating layers of matrix polymer such as EVA and barrier polymer such as EVOH. U.S. Pat. No. 6,399,170 discloses a plastic closure and method of manufacture in which the liner is compression molded in situ on the interior surface of the closure base wall, and includes a dispersion of barrier polymer platelets, such as EVOH, in a matrix polymer such as EVA.

It is desirable to provide a closure and liner construction, a method of closure manufacture, and a closure and container package that are particularly well adapted for high-temperature applications. Such high-temperature applications include, for example, applications in which the container is filled with product while the product is hot, such as so-called hot fill applications. High-temperature applications also include applications in which the filled package is subjected to pasteurization or retort after filling. During retort applications, for example, the filled package may be subjected to a temperature of 265° F. for fifteen minutes or more. High-temperature situations can also occur when a package is filled with a carbonated beverage and stored or transported under high-temperature conditions in which the internal pressure within the container can increase dramatically. In all of such high-temperature situations, the container closure is subjected to elevated internal pressure, which tends to distort or dome the closure base wall and lift the sealing liner away from sealing engagement with the container finish.

U.S. Patent document 2003/0098286 discloses a plastic closure that has particular utility for such high temperature and retort applications. The closure includes a shell having a base wall and a skirt with one or more internal threads for securing the closure to a container finish. In some embodiments, a plastic disk is loosely captured within the closure shell. An annular ring extends axially from the disk adjacent to but spaced from the periphery of the disk. A resilient liner is molded onto the disk over at least the central portion of the disk and over the ring on the disk. The ring urges the liner into sealing engagement with the radially inner edge and the axial end of the container finish when the closure is secured to the container finish. In some embodiments of the closure, the disk includes an annular rib around the periphery of the disk, with the liner extending around the inner periphery of the rib. The disk thus urges the liner into sealing engagement with the inner and outer edges of the container finish as well as the axial end of the container finish. When a filled package that includes such a closure is subjected to elevated temperatures, during retort applications for example, the liner is maintained in sealing contact with the container finish.

U.S. Patent document 2004/0108294 discloses a plastic closure, package and method of manufacture that are particularly well suited for high-temperature and retort applications. The closure includes a plastic closure shell having a base wall with a central opening and a skirt with at least one internal thread or bead for securing the closure to a container neck finish. A plastic disk is retained within the shell parallel to but spaced from the base wall. The disk includes a plurality of axially extending spacer elements around the disk to engage the undersurface of the base wall and space the disk from the base wall of the shell. A plurality of angularly spaced fingers preferably extend from the disk through the central opening of the shell base wall to retain the disk within the shell. A resilient liner is disposed on an underside of the disk, preferably by being compression molded in situ, for sealing engagement with the container neck finish.

It is a general object of the present disclosure to provide a closure, package and method of manufacture of the general type disclosed in the above-noted U.S. Patent documents, in which the sealing liner is economically molded in situ onto the undersurface of the disk.

The present disclosure embodies a number of aspects or inventions that can be implemented separately from or in combination with each other.

A method of making a closure that includes an end panel and a sealing liner on one face of the end panel, in accordance with a first aspect of the present disclosure, includes providing an injection mold having at least first and second mold elements, at least one of which is movable with respect to the other. The first and second mold elements are positioned to form a first mold cavity, and the end panel is injection molded within the first mold cavity. At least one of the first and second mold elements then is moved to form a second mold cavity in which a face of the end panel forms at least one mold cavity wall, and the sealing liner is injection molded onto the face of the end panel. The end panel and liner are then removed from the second mold cavity. The liner/panel subassembly thus is provided more easily and economically than if the liner were compression molded in situ onto the undersurface of a separately formed panel. The closure preferably is a two-piece closure, and the method preferably includes the step of assembling the end panel to a separately formed closure shell. The closure may be a one-piece closure in which the liner is molded to the undersurface of the end panel that forms the base wall of a closure shell.

A two-piece plastic closure in accordance with another aspect of the present disclosure includes a plastic closure shell having a base wall with a skirt for securing the closure to a container neck finish. A plastic disk is loosely retained within the shell parallel to but separate from the base wall. The disk includes a plurality of axially extending spacer elements around the disk to engage an undersurface of the base wall and space the disk from the base wall of the shell. A resilient sealing liner is molded in situ on an underside of the disk in a two-material molding operation for sealing engagement with a container neck finish. There preferably are angular gaps between the spacer elements to permit flow of fluid through a central opening on the closure shell, between the base wall and the disk, and through the gaps to flush debris from between the closure shell and disk. The disk preferably includes angularly spaced fingers that extend from the disk through the central opening of the shell base wall to retain the disk within the shell.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure, together with additional objects, features, advantages and aspects thereof, will best be understood from the following description, the appended claims and the accompanying drawings, in which:

FIG. 1 is a fragmentary partially sectioned elevational view of a closure and container package in accordance with one exemplary embodiment of the disclosure;

FIG. 2 is an exploded fragmentary view of the sealing disk/liner subassembly in the package of FIG. 1;

FIG. 3 is a fragmentary sectional view of a modification to the disk/liner subassembly of FIG. 2; and

FIG. 4 is a fragmentary elevational schematic diagram of a mold for making the sealing disk/liner subassembly of FIG. 2 in a two-material molding operation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The disclosures of above-noted U.S. Patent documents 2003/0098286 and 2004/0108294 are incorporated herein by reference.

FIGS. 1 and 2 illustrate a closure and container package 20, in accordance with one presently preferred but exemplary embodiment of the disclosure, as including a container 22 having a cylindrical neck finish 24. A closure 26 is externally secured to container neck finish 24. Closure 26 in the illustrated embodiment of the disclosure is a two-piece assembly that includes a ring-shaped closure shell 28, and a disk 30 having a sealing liner 32 molded in situ on the undersurface of disk 30. Closure shell 28 includes a base wall 34 and a cylindrical skirt 36 with one or more internal threads or thread segments 38 for engagement with one or more external threads or thread segments 40 on container neck finish 24. Disk 30 has axially extending fingers 42 for spring-mounting disk 30 within a central opening in shell base wall 34. A tamper band 44 is frangibly connected to the lower edge of skirt 36 for cooperation with a bead 46 on neck finish 24 to separate band 44 from skirt 36 when closure 26 is initially removed from container 22, thereby providing indication of potential tampering. A plurality of spacer elements 48 (FIG. 2), preferably in the form of angularly spaced segments of a circumferential bead 50 are provided on the upper surface of disk 30 for spacing disk 30 from the under surface of base wall 34. Water or other fluid may be directed through the opening in base wall 34, between spring fingers 42, between shell base wall 34 and disk 30, through the gaps in bead 50, and then between neck finish 24 and skirt 36 to flush debris from between the closure disk and shell. Container 22 may be of glass or plastic construction. Closure shell 28 and disk 30 preferably are of relatively rigid plastic construction such as polypropylene. Liner 32 may be of any suitable relatively soft flexible and resilient construction.

FIG. 3 illustrates a modified disk 52, in which lands 54 are provided between spring fingers 42 and spacer bead 50. In both of the embodiments of FIGS. 2 and 3, there is an annular ring or wall 56 that extends axially downwardly from the periphery of disk 30 or 52, and an annular bead or hump 58 is spaced radially inwardly from wall 56. (Directional words such as “upper” and “lower” are employed by way of description and not limitation with respect to the upright orientation of the package illustrated in FIG. 1. Directional words such as “axial” and “radial” are employed by way of description and not limitation with respect to the axis of the container neck finish, the closure skirt or the liner disk as applicable.) Liner 32 preferably extends at least around the radially outer edge of bead 58, the axially facing undersurface of disk 30 or 52 between bead 58 and wall 56, and at least the axially upper edge of wall 56. Sealing liner 32 more preferably extends along the entire undersurface of disk 30 or 52, and includes barrier material in layers or platelets to retard migration of gases and the like through the liner. Such sealing/barrier liners are disclosed, for example, in U.S. Pat. Nos. 6,371,318 and 6,399,170. Suitable non-barrier liner constructions are disclosed in U.S. Pat. Nos. 4,984,703 and 5,306,542.

In accordance with the illustrated embodiments of the present disclosure, liner 32 is molded onto the undersurface of end-panel disk 30 or 52 in a multi-material or a multi-component injection molding operation, preferably a two-material injection molding operation. A multi-material injection molding operation is one in which multiple material parts or components are molded in a single machine cycle. An exemplary mold 60 is illustrated schematically in FIG. 4. Mold 60 includes a plate 62 having a cavity-forming undersurface 64, and a core 66 having a cavity forming upper surface 68. Core 66 in the illustrated mold is a two-piece core to facilitate molding of spring fingers 42 (FIGS. 1-3). Core 66 is coupled to a plate 70 or the like for movement toward and away from plate 62. As a first step in the molding operation, core 66 is moved to a fully closed position relative to plate 62 to form a first cavity for molding disk 30 or 52. Disk material is injected into this mold cavity, such as through a gate 72. The disk material is of relatively rigid plastic construction such as polypropylene. Core 66 is then moved slightly away from plate 62 so as to form a second mold cavity between the upper surface (in the orientation of FIG. 4) of the just-molded disk 30 or 52 and the opposing surface 64 of plate 62. FIG. 4 illustrates mold 60 in this configuration, with the liner mold cavity being formed between just-molded disk 30 and surface 64 of plate 62. Liner material is then injected through a second gate 74 to injection mold the liner within the second mold cavity. Gate 74 is laterally spaced from gate 72 in the illustrated embodiment. Disk 30 is imperforate as molded, and the liner material is injected directly into the mold cavity and not through the disk. The liner is of any suitable relatively soft flexible resilient material. Plate 62 is then moved away from core 66 and the molded disk/liner subassembly is stripped or otherwise removed from the core, such as by movement of inner core pin 76 outwardly relative to outer core sleeve 78.

The method of manufacture and the mold schematically illustrated in FIG. 4, which can be termed a core-back method, is only exemplary. Other techniques can be used. For example, in a rotary stripper method, a stripper plate rotates and carries the part from a first shot cavity/core location. The tooling might include two sets of cavities and cores, one stripper plate and two stripper components. As another example, a core plate rotates and carries the part from a first shot cavity/core location to a second shot cavity/core location. The tooling might include two sets of cavities, and two sets of cores mounted in a rotary indexing plate. The core plate may rotate along the axis of the direction of pull. As a robotic transfer third example, the mold opens after a first shot is injected, and a robotic arm picks the component from the first shot location and places the component in the second shot location. The robot retracts and the mold closes again, molding the second shot around the first component and molding a new shot of the first component. When the mold opens again, the second component is ejected while the robotic arm transfers the new first component to the second shot location.

There thus have been disclosed a closure, a package and a method of manufacture that fully satisfies all of the objects and aims previously set forth. The disclosure has been presented in conjunction with presently preferred exemplary embodiments, and additional modifications and variations have been discussed. Other modifications and variations readily will suggest themselves to persons of ordinary skill in the art in view of the foregoing discussion. For example, mold 60 could be configured to mold a one-piece closure shell and a sealing liner onto the undersurface of the shell base wall. Mold 60 preferably is configured to mold multiple disk/liner subassemblies in a single operation. The disclosure is intended to embrace all such modifications and variations as fall within the spirit and broad scope of the appended claims.

Claims

1. A method of making a closure that includes an end panel of relatively rigid plastic construction and a sealing liner of relatively flexible resilient construction on one face of said end panel, said method including the steps of: (a) providing an injection mold that includes at least first and second mold elements, at least one of which is movable with respect to the other, (b) positioning said first and second mold elements to form a first mold cavity, (c) injection molding said end panel of relatively rigid plastic construction within said first mold cavity, (d) moving at least one of said first and second mold elements to form a second mold cavity in which a face of said end panel forms at least one mold cavity wall, (e) injection molding said sealing liner of relatively flexible resilient construction on said face of said end panel, and (f) removing said end panel and liner from said second mold cavity.

2. The method set forth in claim 1 wherein said steps (c) and (e) are carried out by injecting the panel and liner materials through laterally spaced gates.

3. The method set forth in claim 1 wherein said steps (b) and (c) are such that said end panel is imperforate.

4. The method set forth in claim 1 of making a two-piece closure that includes the step of assembling a separately formed closure shell to said end panel.

5. The method set forth in claim 1 of making a one-piece closure wherein said end panel is molded in said step (c) as a base wall of a one-piece closure shell.

6. A plastic closure that comprises: a plastic closure shell including a base wall with a central opening and a skirt for securing the closure to a container neck finish, a plastic disk retained within said shell parallel to but separate from said base wall, said disk including a plurality of axially extending spacer elements around said disk to engage an underside of said base wall and space said disk from said base wall of said shell, angularly spaced fingers extending from said disk through said central opening of said base wall retaining said disk within said shell, and a resilient sealing liner molded in situ on an underside of said disk in a two-material molding operation for sealing engagement with a container neck finish.

7. The closure set forth in claim 6 wherein said spacer elements comprise a plurality of angularly spaced circumferentially aligned bead segments around a peripheral portion of said disk.

8. The closure set forth in claim 6 wherein said disk is free to rotate with respect to said shell.

9. The closure set forth in claim 6 wherein said disk has an axially extending circumferentially continuous ring around a periphery of said disk, and said liner is molded onto a radially inwardly facing surface of said ring.

10. A two-piece plastic closure that comprises: a plastic closure shell including a base wall with a central opening and a skirt with internal means for securing the closure to a container neck finish, and a plastic disk loosely retained within said shell parallel to but separate from said base wall, said disk including an axially extending bead composed of a plurality of angularly spaced bead segments around a peripheral portion of said disk to space said disk from said base wall of said shell, a plurality of angularly spaced fingers extending from said disk through said central opening of said base wall concentrically with said bead and loosely retaining said disk within said shell, and a resilient sealing liner molded in situ on an underside of said disk in a two-material molding operation for sealing engagement with a container neck finish.

11. The closure set forth in claim 10 wherein each of said fingers is received by snap fit within said central opening.

12. The closure set forth in claim 10 wherein said disk has an axially extending circumferentially continuous ring around a periphery of said disk, and said liner is molded onto a radially inwardly facing surface of said ring.

13. A plastic closure that comprises: a plastic closure shell including a base wall with a central opening and a skirt for securing the closure to a container neck finish, and a plastic disk retained within said shell parallel to but separate from said base wall, said disk including a plurality of axially extending spacer elements around said disk to engage an undersurface of said base wall and space said disk from said base wall of said shell, and angular gaps between said spacer elements to permit flow of fluid through said central opening, between said base wall and said disk and through said gaps, and a resilient sealing liner molded in situ on an underside of said disk in a two-material molding operation for sealing engagement with a container neck finish.

14. The closure set forth in claim 13 wherein said spacer elements comprise a plurality of angularly spaced circumferentially aligned bead segments around a peripheral portion of said disk.

15. The closure set forth in claim 13 wherein said disk is free to rotate with respect to said shell.

16. The closure set forth in claim 13 wherein said disk has an axially extending circumferentially continuous ring around a periphery of said disk, and said liner is molded in situ onto a radially inwardly facing surface of said ring.

17. A two-piece plastic closure that comprises: a plastic closure shell including a base wall with a central opening and a skirt for securing the closure to a container neck finish, and a plastic disk loosely retained within said shell parallel to but separate from said base wall, said disk including an axially extending bead composed of a plurality of angularly spaced bead segments around a peripheral portion of said disk to space said disk from said base wall of said shell, and a resilient sealing liner molded in situ on an underside of said disk in a two-material molding operation for sealing engagement with a container neck finish.

18. The closure set forth in claim 17 wherein said disk has an axially extending circumferentially continuous ring around a periphery of said disk, and said liner is molded in situ onto a radially inwardly facing surface of said ring.

19. A closure and container package that includes: a container having a neck finish with at least one external thread segment, and a two-piece plastic closure that comprises: a closure shell including a base wall with a central opening and a skirt with at least one internal thread engaged with said external thread on said container finish, a disk within said shell, said disk including a plurality of angularly spaced axially extending spacer elements around said disk in abutting engagement with said base wall spacing said disk from said base wall, angular gaps between said spacer channels to permit flow of fluid through said central opening, between said base wall and said disk, through said gaps and around said finish, and a resilient sealing liner on an underside of said disk in sealing engagement with said finish around a periphery of said disk, said liner being molded in situ in a two-material molding operation.

20. The package set forth in claim 19 wherein said spacer elements comprise a plurality of angularly spaced circumferentially aligned bead segments around a peripheral portion of said disk.

21. The package set forth in claim 19 wherein said disk is free to rotate with respect to said shell as said closure is secured to and removed from said container.

22. The package set forth in claim 19 wherein said disk has an axially extending circumferentially continuous ring around a periphery of said disk, and said liner is molded in situ onto a radially inwardly facing surface of said ring.