Composite closure with barrier end panel
Composite closures for plastic containers are disclosed. The composite closures include an end panel with oxygen barrier properties. The liner includes a sealing liner or gasket for sealing engagement with a container finish.
This application claims the benefit of U.S. Provisional Patent Application No. 60/580,946, filed Jun. 18, 2004.
The present invention is directed to a composite closure cap for containers such as, but not limited to, plastic bottles and jars. The closure cap includes a disc-shaped end panel that has excellent oxygen barrier properties. Application of the closure cap results in a hermetic seal between the container and the cap. More particularly, the present invention is directed to a composite closure cap with an end panel made substantially of plastic, having oxygen barrier properties and providing a hermetic seal between the container and the cap in a variety of sealing and sterilization environments.
BACKGROUND OF THE INVENTIONComposite closures are well known in the art. Composite closures typically include two parts (thus, the word “composite”), an annular shell or ring with a central opening and a separate end panel covering the central opening. Composite closures are often used in products that are either hot filled or are thermally pasteurized or -sterilized after filling, including products where the entire package (filled container with sealed closure) is subjected to “retorting” (i.e., heating the package to a temperature greater than 220° F.).
Most currently available composite closures include a metal end panel and an annular gasket or ringed liner that provides a hermetic seal between the closure and the container finish. The metal end panel of the metal/plastic composite closure provides a good barrier to oxygen which, if allowed to freely permeate the package, can result in spoilage of the food product. More recently, composite closures where the end panel is made substantially of a non-metal material, such as plastic, have been introduced. Such “all-plastic” composite closures have the advantage of the end panel being less susceptible to corrosion and are less costly to manufacture.
Although, many of the known composite closures have worked satisfactorily, there is a continuing need for composite closures that (1) effectively limit the ingress of oxygen through the closure, (2) seal the package to further limit oxygen ingress at the interface of the container finish and closure cap, (3) provide evidence of tampering, and (4) reduce the cost of manufacture.
Whether the composite closure includes a metal or plastic end panel, but particularly where the end panel is made substantially of plastic, maintaining the integrity of the seal can be particularly problematic in food products packaged in plastic containers that are subjected to retorting. Plastic containers and, more particularly, the plastic container finishes that are subjected to retort often undergo expansion and subsequent contraction. The expansion and contraction of the container finish affects the seal interface between the container and the closure, thus making it more possible that the product can spoil. Thus, there is a need for a closure with the properties previously described that can also be subjected to retort while maintaining the integrity of the seal. The closure of the present invention addresses the above-stated needs.
BRIEF DESCRIPTION OF THE FIGURES
With reference to the Figures, closure cap 10 includes a generally cylindrical shell 12 having a central opening covered by an end panel 20 held within shell 12. Shell 12 is preferably molded from a plastic material such as, but not limited to, polypropylene.
As shown in the Figures and, in particular,
As shown in
The inner circumferential surface of skirt 14 includes, preferably, lifting bead 24, which is located above thread 22 and, more specifically, above the upper terminal end of thread 22. Lifting bead 24 lifts end panel 20 and releases it from its sealing contact with the container during the opening sequence. In a preferred embodiment, lifting bead 24 is substantially horizontal (i.e., does not slope). In one embodiment, bead 24 may extend around the entire circumference of shell 12 (i.e., 360°). More preferably, bead 24 may extend less than 360° around shell 12. In one embodiment, lifting bead 24 extends approximately 240° or less around ring 12 and is continuous (i.e., uninterrupted). However, as shown in
Alternatively, shell 12 may be provided without lifting bead 24. Where bead 24 is absent, release of disc 20 from the container may be achieved by the lifting action of one of the threads 22. This provides for more distance between disc 20 and the lifting means (i.e., thread 22), thereby maximizing the travel distance of disc 20 before the primary seal of the package is broken. This may be advantageous where more sequential opening is desired.
Attached to the terminal end of skirt 14 is a tamper evident band 26. In a preferred embodiment, band 26 may be an extension of skirt 14 and be attached to skirt 14 by a plurality of bridges, at a location below a container retaining bead 60. A continuous or semi-continuous slit 28 or line of weakening between skirt 14 and band 26 is also provided to allow for separation of the cap from band 26 during opening. Band 26 further includes an upwardly and annular inwardly extending retaining member 29 for engagement of bead 60 on the container finish 27. An example of this type of tamper evident band is disclosed in U.S. Pat. No. 5,685,443, incorporated herein by reference. Alternatively, band 26 may include a series of annular ratchets or ratchet segments (not shown) that engage corresponding ratchets 37 (see
In the embodiment of
End panel disc 20 may be made of any suitable plastic composition and may be provided as a single sheet or layer or, as described below, a plurality of sheets. In one embodiment, end panel 20 may be made of one or more layers of polypropylene. Preferably, however, the disc is made of a material(s) that has good oxygen barrier properties. One example is a material that includes a metal component, such as a metal film. Alternatively, non-metallic, (e.g., plastic) substantially oxygen impermeant compositions may also be used. In one embodiment, where oxygen barrier properties are desired, end panel disc 20 is made of a single layer of one or more plastic materials, wherein at least one of the materials is an oxygen barrier.
In another embodiment, end panel disc 20 may be a multi-layered disc 20. A multi-layered disc, as shown, for example, in FIGS. 5 and elsewhere, can be made by a variety of methods. In one embodiment, disc 20 can be made from co-extruded sheets of multiple sheet layers. In still another embodiment, disc 20 can be made by molding, such as by injection molding.
As shown in
Alternatively, the material having the oxygen barrier property (e.g., EVOH) may comprise top layer 32. Thus, in this alternative embodiment, top layer 32 may be an oxygen barrier, middle layer 24 may be a bonding layer and bottom layer 36 may be polypropylene, a copolymer thereof or other polymeric material with insubstantial oxygen barrier properties. Examples of commercially available films that may be useful in the manufacture of end panel 20 include Besela® films available from Kureha Chemicals.
In addition to or as a further alternative to the above, disc 20 may include an oxygen scavenger. Preferably, the scavenger will be combined, blended or otherwise incorporated into a single-layer disc. Where disc 20 is made of multiple layers, bottom layer 36 may include an oxygen scavenger so as to reduce head space oxygen levels after sealing of the container. Examples of suitable scavengers include fine sodium ascorbate particulate or powder. Other examples of oxygen scavengers include iron-based compounds, such as ferrous oxide. Using an oxygen scavenger with one or more layers of an oxygen barrier provides an active and passive barrier system.
Although the thickness of panel will depend, in part, on the size of closure 10, in most of the embodiments described herein a panel thickness of approximately 0.020 inch is preferred. An end panel of reduced thickness may be preferred for purposes of cost reduction and effective heat transfer, particularly during a retort process. In the embodiment, where the top and bottom layers are polypropylene or copolymers thereof with a middle layer of, for example, EVOH in between, the thickness of the middle layer will preferably be approximately 1.2 mils.
Closure cap 10 may also include an annular gasket or liner 38 which is sealingly engageable with the end and preferably inner surfaces of the container finish. Liner 38 may be a full pad liner that substantially covers the entire bottom surface of disc 20. Liner or gasket 38 may be applied to the bottom of end panel disc 20. In a preferred embodiment, sealant is provided as a ring or gasket 38 around the outer periphery of disc 20, as best seen in
Composite closures of the present invention provide further improvement in oxygen barrier properties over more traditional metal/plastic composite closures (i.e., plastic fitment ring with metal end panel). In one study, the oxygen barrier properties of (A) a composite closure including a polypropylene/EVOH/polypropylene end panel 20, lined with a gasket made of the preferred sealant composition described in U.S. Ser. No. 10/400,304 was compared to (B) a metal/plastic composite closure lined with a plastisol composition.
Using an oxygen permeability measuring apparatus, Model Ox-Tran2/61, available from MOCON® of Minneapolis, Minn., closures of the present invention (as described above) exhibited an oxygen ingress rate of typically less than approximately 0.003 cc/package/day/atm, measured at 65% relative humidity (and based on a 40 mm closure), and approximately 0.0025 cc/package/day/atm. Plastic/metal composite closures, lined with plastisol exhibited an oxygen ingress rate of approximately 0.0041 cc/package/day/atm. (Briefly, equipment of the type described above measures oxygen ingress by introducing nitrogen gas into a vessel sealed with a lined closure. The nitrogen gas flushes any oxygen that may be present, due to ingress through the closure, within the sealed vessel. The nitrogen gas exits the vessel through an outlet and the level of captured oxygen is recorded as an electronic signal and reported as cubic centimeters (cc) of oxygen permeating into a package (closure with liner) in a day. The reading is then adjusted to take into account barrier properties of the container or vessel to give a more accurate reading.
As shown in
The closure 10 of the present invention is particularly well-suited for use in hot-fill or retort environments, provided that the container is likewise suitable for use in retort operations. Further alternative embodiments of a “retortable” closure for use with more traditional container materials are also described below.
Preferably, central panel 50 is integral with ring 12 and is made of the same (plastic) material as ring 12 during the molding process. As shown n
In all other respects, closure cap 10, shown in
Not only do the closure caps 10 of
In one embodiment, shown in
As in the previous embodiments, shell 12 of the closure shown in
Shell 12 of composite closure 10, shown in
As shown in
As shown in the Figures, end panel 20 includes a top surface 20a and a lower surface 20b. End panel 20 further includes a central portion 60 and outer peripheral portion 62. In a preferred embodiment, end panel 20 may be provided with a liner (e.g., full pad) or gasket 38 of sealant, as previously described and shown more particularly in
End panel 20 may be provided as a flat disc, as shown in
As contact between container finish 27 and end panel 20 continues during the application process, outer peripheral portion 62 conforms to the shape of the flange bottom surface 21, as shown in
Whether end panel 20 is applied as a flat disc, as shown in
As shown in
While the present invention has been described in connection with various embodiments, it will be apparent to those skilled in this art that modifications and variations may be made therefrom without departing from the spirit and scope of this invention. Accordingly, this invention is to be construed and limited only by the scope of the appended claims.
Claims
1. A composite closure cap for a container comprising:
- an end panel disk made substantially of one or more plastic materials and having oxygen barrier properties, said disk including upper and lower surfaces, and a central portion and an outer peripheral portion terminating in an outer edge;
- a shell including a cylindrical, downwardly extending skirt and an annular top flange overlying and in contact with the upper surface of said outer peripheral portion of said disk;
- a sealing liner on at least the outer peripheral portion of said lower surface of said disk.
2. The composite closure of claim 1 wherein said disk comprises a plurality of sheets wherein at least one of said sheets is made at least in part from a material that is a substantial barrier to oxygen.
3. The composite closure of claim 2 wherein said disk includes top, middle and bottom sheets, wherein at least one of said top or middle sheets is made at least in part from a material that is a barrier to oxygen.
4. The composite closure if claim 3 wherein said disk comprises a top layer made at least in part of polypropylene or copolymer thereof, a middle sheet made at least in part of EVOH, and a bottom sheet made at least in part of polypropylene or copolymer thereof.
5. The composite closure of claim 3 wherein said disk comprises a top sheet made at least in part of a material that is a barrier to oxygen, said bottom sheet is made at least in part of polypropylene or copolymer thereof, and said middle sheet is made of a material selected to adhere to said top and bottom sheets.
6. The composite closure of claim 3 wherein at least one of said sheets includes an oxygen scavenger.
7. The composite closure of claim 1 wherein said flange defines a central opening in said shell.
8. The composite closure of claim 1 further including a panel overlying and being spaced from said inner portion of said central portion of said end panel disk.
9. The composite closure of claim 8 wherein said overlying panel is integrally formed with said shell.
10. The composite closure of claim 9 wherein said overlying panel is joined to said flange by a plurality of annularly spaced connecting arms.
11. The composite closure of claim 1 wherein said skirt includes at least one preformed thread on the inner circumferential surface of said skirt.
12. The composite closure of claim 1 including at least one preformed thread and a preformed bead on the inner circumferential surface of said skirt, wherein said bead is spaced above the upper terminal end of said thread.
13. The composite closure of claim 12 wherein said bead is continuous.
14. The composite closure of claim 12 wherein said bead extends for less than 360°.
15. The composite closure of claim 12 wherein said preformed bead is non-continuous.
16. The composite closure of claim 12 wherein said the outside diameter of said end panel disk is greater than the diameter of said preformed bead.
17. The composite closure of claim 1 including a plurality of annularly spaced vents in said flange.
18. A composite closure cap for a container comprising:
- an end panel disk made substantially of one or more plastic materials and having oxygen barrier properties, said disk including a upper and lower surfaces, and a central portion and an outer peripheral portion terminating in an outer edge;
- a shell including a cylindrical, downwardly extending skirt including an annular top flange including a top surface a bottom surface and a radially inner surface between said top and bottom surfaces, said flange overlying at least the outer peripheral portion of said disk such that said bottom surface of said flange is in contact with the upper surface of said outer peripheral portion of said disk;
- wherein at least part of said disk upper surface is exposed to the outside environment; and
- a sealing liner on at least the outer peripheral portion of said lower surface of said disk.
19. The composite closure of claim 18 including a panel overlying said inner portion of said central portion of said end panel disk.
20. The composite closure of claim 19 wherein said overlying panel is integrally formed with said shell.
21. The composite closure of claim 19 wherein said overlying panel is joined to said flange by a plurality of annularly spaced connecting arms.
22. The composite closure of claim 18 including a plurality of annularly spaced vents in said flange.
23. The composite closure of claim 22 wherein said vents are located on said radially innermost surface of said flange.
24. The composite closure of claim 22 wherein said vents are located in said top surface of said flange.
25. A composite closure cap for a container comprising:
- a shell including a downwardly extending skirt portion and an annular top flange, said flange including a top surface and a bottom surface wherein at least said bottom surface of said flange has a generally C-shaped profile whereby said flange bottom surface includes a radially inner downwardly extending inner portion, a radially outer downwardly extending portion and a curved portion between said radially inner and outer portions;
- said end panel disk made substantially of one or more plastic materials and having oxygen barrier properties, said disk including upper and lower surfaces, and a central portion and an outer peripheral portion terminating in a free edge, wherein said outer peripheral portion of said disk is substantially conformed to and in contact with at least said downwardly extending and curved top portions of said flange bottom surface; and
- a sealing liner on at least the outer peripheral portion of said lower surface of said disk where said disk is substantially conformed to said radially downwardly extending and curved top portions of said flange bottom surface.
26. The composite closure of claim 25 wherein said disk comprises a plurality of layers and wherein at least one of said layers is made at least in part from a material that is a barrier to oxygen.
27. The composite closure of claim 25 wherein said disk includes a top, middle and bottom layers wherein at least one of said top or middle layers is made at least in part from a material that is a substantial barrier to oxygen.
28. The composite closure of claim 27 wherein said disk comprises a top layer made at least in part of a polypropylene or copolymer thereof, a middle sheet made at least in part of EVOH, and a bottom sheet made at least in part of a polypropylene or copolymer thereof.
29. The composite closure of claim 25 wherein said flange top surface has a generally C-shaped profile, whereby said top surface includes a radially inner downwardly extending inner portion, a radially outer downwardly extending portion and a curved portion between said radially inner and outer portions.
30. The composite closure of claim 29 including a plurality of annularly spaced vents in said flange.
31. The composite closure of claim 30 wherein said vents comprise openings in between said bottom and top surfaces of said flange.
32. The composite closure of claim 31 wherein said vents are located between said curved and radially outer portions of said flange top and bottom surfaces.
33. The composite closure of claim 25 wherein said gasket is made of a material selected to sealingly engage a container finish made of a material that is susceptible to shrinkage during cooling following exposure to temperatures in excess of 220° F.
34. The composite closure of claim 25 wherein said gasket is made of a material selected to adhere to a container finish made of a polyethylene terephthalate.
35. A method of making a composite closure cap comprising:
- molding an outer plastic shell including a cylindrical skirt and an annular top flange, said skirt defining a central mouth and said flange having a top surface, a bottom surface and a generally C-shaped cross-section profile whereby said bottom surface includes a radially downwardly extending inner portion, a radially downwardly outer portion, a curved portion between said radially inner and outer portions;
- providing a circular disk having a top surface and a bottom surface, said disk including a central portion and a outer peripheral portion;
- applying a sealant material to at least the outer peripheral portion of said disk bottom surface;
- introducing said disk into said shell through said central mouth.
36. The method of claim 35 comprising providing a generally flat, flexible circular disk.
37. The method of claim 35 further comprising providing an area of weakening in said disk between said disk central portion and said outer peripheral portion.
38. The method of claim 37 comprising providing said area of weakening in said disk by forming a notch in said disk between said central portion and said outer peripheral portion.
39. The method of claim 37 comprising pressing said outer peripheral portion of said disk against said flange to substantially conform said outer peripheral portion to the shape of said inner radial and top portions of said flange bottom surface.
40. The method of claim 35 comprising providing a disk having a central portion and outer peripheral portion, said outer peripheral portion having a generally C-shaped cross-section and including a radially inner, downwardly extending surface and a radially outer curved surface.
41. The method of claim 40 comprising thermoforming said disk to provide disk having an outer peripheral portion with a generally C-shaped cross-section, including a radially inner, downwardly extending surface and a curved surface.
42. The method of claim 41 comprising applying said sealant prior to said thermoforming.
43. A composite closure cap for a container comprising:
- an end panel disc substantially made of one or more plastic materials and having oxygen barrier properties;
- a plastic ring including a downwardly extending skirt and upper radially inwardly extending flange, said flange overlying the outer periphery of said disc;
- a sealant applied to the bottom surface of said disc.
44. The composite closure of claim 43 wherein said sealant is applied to the outer peripheral portion of said disc bottom surface as a gasket.
45. The composite closure of claim 43 wherein said end panel comprises a single sheet of one or more plastic materials.
Type: Application
Filed: Jun 17, 2005
Publication Date: Dec 29, 2005
Inventors: James Taber (Aurora, IL), Stephen Kras (Chicago, IL)
Application Number: 11/156,076