U.S. patent application number 10/599249 was filed with the patent office on 2008-02-14 for closure with integral gas barrier.
This patent application is currently assigned to BAPCO CLOSURES RESEARCH LTD.. Invention is credited to Peter Michael McGeough, Henning Von Spreckelsen.
Application Number | 20080035600 10/599249 |
Document ID | / |
Family ID | 32188609 |
Filed Date | 2008-02-14 |
United States Patent
Application |
20080035600 |
Kind Code |
A1 |
McGeough; Peter Michael ; et
al. |
February 14, 2008 |
Closure with Integral Gas Barrier
Abstract
A cap (2) suitable for use with a PET beverage bottle has an
integral gas barrier provided by a plastics-coated aluminium foil
disc (30) having its peripheral edge (32) embedded into the
plastics internal or external surface (40) of a top panel (4) of
the cap or of a valve (20). A plastics component (28) from which
the cap (2) can be produced is described. The component (28) has a
recess (48) defined by a sacrificial wall (50) formed inwardly of a
resealing valve (20).
Inventors: |
McGeough; Peter Michael;
(Woking, GB) ; Von Spreckelsen; Henning; (Woking,
GB) |
Correspondence
Address: |
CHRISTOPHER J. KULISH, ESQ
HOLLAND & HART LLP
P. O. BOX 8749
DENVER
CO
80201-8749
US
|
Assignee: |
BAPCO CLOSURES RESEARCH
LTD.
SUNDIAL HOUSE, HIGH STREET, HORSELL
WOKING
GB
|
Family ID: |
32188609 |
Appl. No.: |
10/599249 |
Filed: |
March 24, 2005 |
PCT Filed: |
March 24, 2005 |
PCT NO: |
PCT/GB05/01109 |
371 Date: |
September 22, 2006 |
Current U.S.
Class: |
215/341 ;
264/487 |
Current CPC
Class: |
B65D 41/0407 20130101;
B65D 41/0414 20130101; B65D 41/045 20130101; B65D 41/325
20130101 |
Class at
Publication: |
215/341 ;
264/487 |
International
Class: |
B65D 41/04 20060101
B65D041/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2004 |
GB |
0406630.4 |
Claims
1-27. (canceled)
28. A method of producing a cap (2) from an existing plastics
component (28), comprising a top panel (4) surrounded by a skirt
(6), and a plastics coated aluminium gas barrier foil (30), the
method comprising the steps of placing the barrier foil (30)
adjacent the top panel (4) and induction heat welding the foil to
the panel (4) by melting the component indirectly by contact with
the heated foil.
29. A reclosable plastics cap (2) having a top panel (4), a skirt
(6), a gas barrier (30) to inhibit gas flow through the cap (2),
and a closed plug (92) substantially filling a void inside the cap
to define a valve (20) adapted to fit inside and seal against an
inner wall of a neck of a container to which the cap is fitted,
characterised in that the cap can be resealed and in that the gas
barrier is provided by means of a plastics coated aluminium foil
(30) induction heat sealed to plastics material of the cap.
30. A reclosable plastics cap (2) having a top panel (4) and a
skirt (6), wherein a plastics coated aluminium foil liner (30) has
a peripheral edge (32) that is embedded and fused into an external
surface (70) of the skirt (6) or top panel (4) of the cap (2).
31. A cap (2) as claimed in claim 30, wherein an opening (66) is
formed in the top panel (4).
32. A cap (2) as claimed in claim 30, wherein a valve (20), adapted
to fit inside and seal against an inner wall of a neck of a
container to which the cap is fitted, depends from the top panel
(4).
33. A cap (2) as claimed in claim 32, wherein the valve (20) is
provided on a plate (62), which traps the foil liner (30) to an
internal surface of the top panel (4).
34. A cap (2) as claimed in claim 33, wherein the plate (62) has an
opening (68) which cooperates with a corresponding opening (66) in
the top panel to enable the foil to be pierced to access the
contents of a container closed by the cap in use.
35. A cap (2) as claimed in claim 29, wherein the foil liner (30)
forms or covers an internal or external end face of the plug
(92).
36. A cap (2) as claimed in claim 29, wherein an interior of the
plug (92) is defined by a recess (90) lined with the foil liner
(30).
37. A cap (2) as claimed in claim 29, wherein an interior of the
plug (92) is lined with EVOH or other similar gas barrier plastics
material.
38. A cap (2) as claimed in claim 29, wherein the plastics coated
aluminium foil (30) extends across the entire width of the valve
(20).
39. A cap (2) as claimed in claim 38, wherein the aluminium foil
also extends up or down the wall of the valve (20).
40. An assembly of a cap as claimed in claim 29 and a glass,
plastics, steel or aluminium bottle, jar or any other
container.
41. An assembly of a cap as claimed in claim 29 and a container
made of paperboard or composite material.
42. An assembly of a cap as claimed as claimed in claim 29 and a
thermoformed container.
43. A method of producing a cap (2) from a plastics component (28)
comprising a top panel (4) surrounded by a skirt (6), a receiving
recess (48) for a barrier foil, and a sacrificial wall (50), the
method comprising the steps of placing a barrier foil (30) into the
recess (48) and heating the wall (50) to melt the plastic material
of the wall in order to embed an edge (32) of the foil (30) into
the cap (2).
44. A method as claimed in claim 43, wherein the heating step
comprises induction heating the foil (30) to melt the wall
(50).
45. A method as claimed in claim 43, wherein the foil (30) is
oversized and when placed into the recess (48) has its peripheral
edge (32) pressed against an inner surface of the recess (48).
46. A plastics component (28) for use in manufacturing a cap (2) by
method as claimed in claim 1 or 16, wherein an annular wall (20,
50) extends from the top panel (4) in order to define a recess (48)
to receive the foil liner (30) wherein the wall (20, 50) has an
intermediate, reduced cross-section portion (56) in order to enable
a lower part (54) of the wall to be folded back towards the top
panel in order to retain the peripheral edge (32) of the foil liner
during production.
47. A cap (2) as claimed in claim 32, wherein the plastics coated
aluminium foil (30) extends across the entire width of the valve
(20).
48. A cap (2) as claimed in claim 47, wherein the aluminium foil
also extends up or down the wall of the valve (20).
49. An assembly of a cap as claimed in claim 30 and a glass,
plastics, steel or aluminium bottle, jar or any other
container.
50. An assembly of a cap as claimed in claim 30 and a container
made of paperboard or composite material.
51. An assembly of a cap as claimed as claimed in claim 30 and a
thermoformed container.
52. A method as claimed in claim 44, wherein the foil (30) is
oversized and when placed into the recess (48) has its peripheral
edge (32) pressed against an inner surface of the recess (48).
Description
TECHNICAL FIELD
[0001] The present invention relates to closures with integral gas
barriers. More specifically the invention relates to the field of
closures for packaging for liquids that require a gas or humidity
barrier. The invention is relevant in particular to the field of
glass, plastics, including thermoformed plastics, or metal bottles
or jars and unpressurised cartons.
[0002] Certain liquids, such as beer, are particularly susceptible
to oxygen levels. The control of oxygen levels is also essential in
aseptic and extended shelf life (ESL) packaging to prevent
spoilage, tainting and discolouration due to the entry of
oxygen.
[0003] The invention is therefore concerned with the control of
gases within a container and, more specifically, the impact of the
closure on this issue. A gas barrier is required to prevent both
the escape of carbon dioxide from carbonated drinks packed under
pressure, and the ingress of oxygen through the closure. Air can
also be introduced into the container during a capping process.
BACKGROUND ART
[0004] Crown cork caps that are crimped onto a glass bottleneck
provide an effective packaging solution with excellent gas barrier
characteristics.
[0005] Aluminium screw caps are also used with glass bottles. These
have a post-applied liner material fitted to provide a seal.
Another closure that relies on the gas barrier that metal provides
is a ring-pull closure consisting of a metal cap moulded over the
mouth and neck and provided at one edge with a ring-pull to enable
removal. This closure is not reclosable. WO 03/022705 (Technocaps
Limited--Mestriner) teaches the use of a plain metal sealing disk
that is retained on a bead at the bottle rim by a plastics ring
that can be removed by means of a tab. Again the Technocaps closure
is not reclosable.
[0006] Screw-on metal closures are less suitable for use with
plastics bottles as their use requires high axial loading that
would damage a plastics bottleneck.
[0007] Another option is to use a moulded closure with a loose
multi-layered foil liner, which is inserted into the closure body.
This assembly is applied after filling. The assembled closure is
exposed to an induction energy field thus sealing the foil to the
bottleneck. This foil seal provides a gas barrier. However, such
loose foil seals are typically very difficult to remove and the
closure system provides poor reseal performance once the foil
element is removed. This solution is also not suitable for aseptic
applications as microbes and contamination get trapped behind the
loose foil liner. The cap sterilisation systems employed are unable
to eradicate such contamination.
[0008] Developments in gas barriers for bottles, including
scavenging agents added to PET polymers, mean that it is now
practicable to use plastics bottles for products such as beer and
other oxygen-sensitive beverages. However there is a need for a
closure suitable for use with a plastics bottle that offers a high
integrity gas barrier and is preferably reclosable.
PRIOR ART SOLUTIONS
[0009] A typical screw closure for use with a bottle is described
in U.S. Pat. No. 4,658,976 (Aluminum Company of America--Pohlenz).
A top seal is provided by means of a plastics liner in the top of
the cap to seal against a rim of the bottle mouth. This type of cap
is commonly used for mineral water and carbonated soft drinks.
[0010] The presence of a valve that seats inside a bottle mouth is
a preferred solution for resealability in a reclosable plastics
closure. A good seal is essential for plastics containers that have
been processed in an in-line pasteuriser as this can result in
heat-induced deformations of the bottleneck. A long valve is
preferable to eliminate the leakage risk arising from this
deformation.
[0011] Although Aluminum Company of America does not specifically
address the gas barrier problem; others have used the same plastics
liner or wad approach to address this problem. EVOH (ethylene vinyl
alcohol) or rubber materials have been tried, but although these
provide a gas barrier, they do not form good humidity barriers.
Owens-Illinois Closure Inc have, for example, announced a
moulded-in liner seal that uses multiple thin layers of barrier
material as described in U.S. Pat. No. 6,399,170 (Hock). This
material tends to be expensive and brittle and is not well suited
to function as a seal. Accordingly various designs have been
suggested for use of such a barrier with other sealing structures.
See EP-A-1081 058 (Riffer) and US 2003/0057175 A1 (Willingham et
al). These moulded liner sealers have been developed to provide gas
barrier levels equal to or better than foil. While aluminium foil
has excellent gas and humidity barrier properties, it is
undesirable to allow exposed metal to come into contact with many
products due to its propensity to cause corrosion under conditions
of prolonged contact.
[0012] The problems of providing an oxygen barrier with a plastic
or metal/plastic or metal closure are also discussed in WO 02/14171
(White Cap, Inc). An oil-free, single layer plastics liner is
proposed as a liner to provide a gas barrier and also to act as a
sealing gasket. Such a solution results in a closure that requires
a high torque for removal if a good seal is to be achieved.
Closures made of composite materials are also relatively expensive
to produce. Sealing against a rim of the bottle mouth also requires
the rim to be level and smooth. These conditions are not always
possible after heat treatment.
[0013] In order to minimise the amount of oxygen entrained in a
bottleneck during the capping process, it is usual for nitrogen to
be continuously blown over the necks of the bottles. The inert
nitrogen displaces any oxygen trapped in the neck of the bottle
above the contents. However, the nitrogen does not displace oxygen
that is trapped in the caps as it is lowered onto the necks. As a
result a small but significant amount of oxygen is entrained and
inevitably becomes trapped within the sealed bottles. This is a
particular problem for screw cap closures.
Technical Problem
[0014] To provide a complete solution for gas-tight packaging in
plastics containers that may have distorted necks, it is necessary
to solve the technical problem of providing a reclosable,
resealable closure with an integral gas barrier that can be fitted
with minimal bottle top loading pressures during capping whilst
being aseptic-compatible.
[0015] A further technical problem is presented by the need to
prevent oxygen being introduced into the container when the closure
is fitted.
Solution of the Invention
[0016] Instead of plastics liners and wads, the present invention
provides a solution in which the advantages of an aluminium foil
gas barrier are provided within a plastics cap. It is therefore
possible to produce closures made from two materials, a plastics
cap component and lightweight, flexible coated aluminium foil, in a
variety of configurations that solve the technical problems
identified.
[0017] The present invention provides a reclosable plastics cap
having a top panel, a skirt and a plastics coated aluminium foil
element fused to the cap to provide a gas barrier inhibiting gas
flow through the cap, such that a peripheral aluminium edge of the
foil element cannot come into contact with the contents of a
container closed by the cap in use. This can be achieved by
arranging the gas barrier on the top panel or sandwiched above a
valve plate. New design possibilities are opened up by an
appreciation that the gas barrier does not need to face the
contents of the container to be effective.
[0018] Alternatively the present invention also provides a
reclosable plastics cap having a top panel and a skirt, wherein a
plastics-coated aluminium foil liner has a peripheral edge that is
embedded and fused into a surface of the cap.
[0019] By using a plastics-coated liner with an embedded edge the
contamination risk from an exposed aluminium edge is avoided. The
key to the fusing of the edge into the cap lies in a realisation
that with a suitable arrangement of sacrificial walls or the like
in the component from which the cap is made induction heating can
be employed to embed the edge completely without leaving any
crevices that would prevent effective sterilisation of the assembly
cap.
[0020] This type of cap may be used together with a valve to
provide resealability. It can also be used with threaded or snap-on
caps. The edge is preferably embedded into the internal surface of
the top panel or of a valve of the cap, but may also be embedded
into the external surface of the top panel or wrapped over the top
of the cap and embedded into the skirt. By fusing the edge into the
material of the cap the same level of protection is provided as
with the normal coating on the major surfaces of the foil.
[0021] The invention also provides a plastics component for use in
manufacturing such a cap, wherein an annular wall extends from the
top panel in order to define a recess to receive the foil liner.
The recess can be beneath or on top of the top panel. Preferably
the annular wall has an intermediate, reduced cross-section portion
in order to enable a lower part of the wall to be folded back
towards the top panel in order to retain the peripheral edge of the
foil liner during production.
[0022] The invention also provides a reclosable plastics cap having
a top panel, a skirt and a gas barrier to inhibit gas flow through
the cap, characterised in that a closed plug substantially fills a
void inside the cap and defines a valve adapted to fit inside and
seal against an inner wall of a neck of a container to which the
cap is fitted.
[0023] The present invention further provides a method of producing
a cap from a plastics component comprising a top panel surrounded
by a skirt, a receiving recess for a barrier foil, and a
sacrificial wall, the method comprising the steps of placing a
barrier foil into the recess and heating the wall to melt the
plastic material of the wall in order to embed an edge of the foil
into the cap.
[0024] The heating is preferably carried out by induction heating
the foil to melt the wall, as this avoids contact with the cap and
promotes clean and quick production.
[0025] Such a method is aseptic-friendly as the resulting cap has
smooth surfaces and no additional crevices in which bacteria may
escape when the cap is being rinsed and flushed.
[0026] Other features of the invention are defined in the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order that the invention may be well understood, four
embodiments thereof will now be described, by way of example only,
with reference to the accompanying diagrammatic drawings, in
which:
[0028] FIG. 1 shows a longitudinal half-section through a first
embodiment of a cap shown incompletely assembled;
[0029] FIG. 2 shows a detail of the cap assembly of FIG. 1 during a
first production step;
[0030] FIG. 3 shows the same detail as FIG. 2 in a finished cap
after a second production step;
[0031] FIG. 4 shows a longitudinal section through a second
embodiment of a cap assembly;
[0032] FIG. 5 shows the same section as FIG. 4 during a first
production step;
[0033] FIG. 6 shows the same section as FIGS. 4 and 5 in a finished
cap after a second production step;
[0034] FIG. 7 shows a longitudinal, exploded section through a
third embodiment of a cap assembly;
[0035] FIG. 8 shows the same section as FIG. 7 after the cap has
been fully assembled;
[0036] FIG. 9 shows a longitudinal section through a fourth
embodiment of an exploded cap assembly;
[0037] FIG. 10 shows the same section as FIG. 9 after the cap has
been fitted to the neck of a container or bottle;
[0038] FIG. 11 shows a variation to a part of the component shown
in FIG. 9;
[0039] FIG. 12 shows a longitudinal, exploded section through a
fifth embodiment of a cap;
[0040] FIG. 13 shows the same section as FIG. 12 after the cap has
been fully assembled;
[0041] FIG. 14 shows a longitudinal section through a sixth
embodiment of a cap; and
[0042] FIG. 15 shows a longitudinal section through a seventh
embodiment of a cap.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0043] A plastics cap 2 has a top panel 4 and a skirt 6. The cap 2
is intended for use with a PET container with a standard PCO.sup.1
or BPF.sup.2 (or any other standard) neck finish with typically a
28, 33, 38, 43 or 45 mm neck diameter. It will be appreciated that
the principle of the invention can be applied to other closures and
diameters. However the embodiments being described are examples
only. 1 Plastics Closures Only--definition of a standard neck
finish as used in the USA 2 British Plastics Federation--definition
of a standard neck finish as used in the United Kingdom
[0044] Seven embodiments are described and in each similar parts
are identified by like reference numerals.
[0045] Referring first to the embodiment of FIGS. 1 to 3, an inner
wall 8 of the skirt 6 has thread formations 10. A lower edge of the
skirt is connected by means of a breakable area 12 to a tamper band
collar 14 that engages with and is retained on an external
formation of the bottleneck in order to provide tamper
evidence.
[0046] An annular sealing valve 20 depends from the top panel 4
inwardly of the skirt 6. The valve is positioned so that its outer
surface 22 will seal against an inner surface of the bottleneck
when the cap 2 is installed.
[0047] The plastics cap 2 as described thus far is conventional and
readily available on the market.
[0048] The cap 2 of the invention is an assembly of the above
described plastics component 28 with an aluminium foil barrier
liner 30.
[0049] The foil liner 30 is positioned inside the valve 20. The
liner 30 is a disc of foil having a peripheral edge 32. The disc 30
is cut from a sheet of plastics coated aluminium foil and therefore
its peripheral edge 32 has exposed aluminium between two thin
plastics layers or membranes. The liner 30 is made of double-sided
induction heat sealing (IHS) foil as described, for example, in
GB237740A (Spreckelsen McGeough Ltd).
[0050] The term foil liner would normally be understood in the art
to refer to a loose element. It will be appreciated that in this
context the foil liner 30 will be welded into the cap 2 as
described in detail below.
[0051] In order to enable the edge 32 to be embedded and fused into
an internal surface 40 of the top panel 4, the cap is produced from
an injection-moulded, plastics component that initially has a
receiving recess 48 for the foil disc 30 formed by an annular
sacrificial wall 50 depending from the internal surface 40 just
inwardly of the valve 20. The wall 50 has an upper part 52 and a
lower part 54 separated by an intermediate, reduced cross-section
portion 56 that runs round the entire circumference of the annular
wall 50. The lower part 54 terminates in an outwardly projecting
flanged foot 58. The lower part 54 is designed so as to be able to
be bent back up about a hinge provided by the reduced cross-section
portion 56 so that it sits inside the upper part 52 with the foot
58 extending parallel to the internal surface 40 of the top panel 4
as shown in FIG. 2. In this configuration the foot 58 retains the
foil disc 30 in position.
[0052] During production, the plastics components 28 are inverted
and a foil disc 30 is punched and placed into each plastics
component 28 inside the wall 50. A tool is then brought down
towards the panel 4. The tool face is shaped to engage with the
lower part 54 of the wall 50 and fold it down over the edge 32 of
the disc and then to further press down and heat (by way of
induction) the assembly so that the plastics material of the wall
50 softens and flows over the edge 32 to embed it into the internal
surface 40 of the top panel 4 as shown in FIG. 3 fusing the
plastics of the coating with the plastics of the component 28. This
results in the foil liner 30 being welded on both sides to the
plastics cap 2. The retaining of the disc step and the embedding
step may be carried out as separate operations. The use of
double-sided IHS foil allows the wall 50 to be melted indirectly by
contact with the heated foil.
[0053] The foil discs 30 can be slightly dished to facilitate
handling and aid accurate location.
[0054] The foil discs 30 may be sterilised prior to insertion in
the recesses 48.
[0055] The foil discs 30 may have a smaller diameter than that of
the neck of a bottle or container to which they are fitted. The
foil liner may also cover the whole surface of the top panel 4
especially if externally mounted.
[0056] When the discs 30 are dropped into the recesses 48, they may
be oversized and have the peripheral edge pressed down the inner
surface of the sacrificial wall 50 in order to ensure that the gas
barrier extends over the largest possible area of the top panel 4.
If the portion of foil that extends down the wall is long, then the
excess foil will need to be folded to fit. In this case the foil 30
and the component 28 must be passed through an aseptic sterilising
rinser prior to assembly in order to maintain aseptic conditions.
It is also possible to heat the foil sufficiently to enable the
folded and wrinkled portions to be wholly embedded within the
surface of the plastics component. A slightly oversized margin of a
thin foil 30 can be smoothly sealed to the interior of the recess
48.
[0057] The caps 2 produced in this way can then be sterilised and
passed to an aseptic filling line. It will be appreciated that due
to the production process there are no remaining crevices in the
internal surface 40 of the top panel such as may exist when a
separate wad or liner is adhered to the internal surface 40.
[0058] It should be noted that the foil liner 30 is not welded to a
spout or neck of the container or bottle, but is welded to the cap
2.
[0059] It will be appreciated that the term "embedding" refers to
the position of the peripheral edge 32 relative to the final
configuration of the top panel 4. In practice the foil may have one
surface welded to the original surface 40 of the top panel of the
component 28 and the other surface welded to the remnants of the
sacrificial wall 50. In the second embodiment described below, the
edge 32 is embedded into the internal surface of the valve, whereas
in the third embodiment the edge 32 and the whole foil 30 is welded
into the top panel 4. In the fourth embodiment, the whole foil is
welded to the external surface of the top panel 4. In addition it
would be possible to wrap the foil over the cap and embed the edge
in the skirt 6. However this is not a preferred option as foil on
the side wall of the cap may be accidentally stripped if the caps
are applied by means of a tool that grips the side wall. Foil in
this position would also cover the knurling typically provided on
the external surface of the skirt 6 to facilitate gripping of the
cap 2 when it is opened and closed. In all these embodiments the
plastics coating of the foil 30 is fused with the plastics of the
cap component 28.
Variations
[0060] Caps 2 may also be produced without a valve 20, or with
valves that can be as long as necessary to provide resealability
against distorted bottlenecks. As illustrated in FIGS. 1 to 3, the
valve 20 is an open-ended cylindrical wall. As the depth of the
valve increases there is scope for it to entrain air, which is
drawn into the bottleneck when the cap is fitted. This can be
avoided by closing the open end of the valve as described in more
detail in the embodiments of FIGS. 11, 14 and 15 below.
[0061] The sacrificial wall 50 may have other configurations that
will nevertheless allow it, in conjunction with a suitably shaped
tool, to sacrifice the material from which it is formed into an
embedment for the edge 32 of the foil disc 30. A tapered wall,
L-shaped wall 50 or a thin wall bent over at the base may be
possible.
Second Embodiment
[0062] In the second embodiment as illustrated in FIGS. 4 and 5,
the sacrificial wall 50 is formed as an extension part 54 of the
valve 20 itself. The annular part 54 is separated from an end of
the valve by a reduced cross-section portion 56. In this embodiment
the recess 48 is the whole of the space within the valve 20. During
production the part 54 is folded inwardly against an inner wall of
the valve 20 as shown in FIG. 5. After heating through the IHS foil
30 the edge 32 of the foil disc 30 becomes embedded in the cap and
more specifically into the wall of the valve 20.
Third Embodiment
[0063] In the third embodiment as illustrated in FIGS. 7 to 8, the
cap 2 is made of a component 28 and a second component or valve
plate 60 formed in the shape of a circular plate 62 that carries
the valve 20.
[0064] The component 28 has a top panel 4 that is thinner than
normal in order to define the barrier-foil receiving recess 48 that
also receives the plate 62 of the second component 60. The recess
48 is defined by a wall 64 inside the top panel. A central part 66
of the top panel 4 need not be present in order to reduce overall
weight in applications where the foil itself has sufficient
pressure-retaining capability to maintain the structural integrity
of the cap 2. A central hole or opening 66 that exposes the foil 30
and corresponds to a hole 68 in the plate 62 can be used to allow
the consumer to puncture the cap with a straw for consumption of
the contents without opening of the cap. Where only weight saving
is required the plate 62 can have a solid top. The central hole 66
may be larger than shown provided there is a sufficient recess 48
to hold the foil disc 30 during assembly. The plate 62 may also
have a central opening 68 when there is no corresponding opening in
the top panel.
[0065] In order to assemble the third embodiment, the disc 30 is
placed in the recess 48 and trapped in position by the plate 62.
When the foil is heated by induction heating the plastic material
of the plate 62 and wall 64 acts in the same way as the sacrificial
wall and embeds the foil in the cap fusing its plastic coating with
the material of the cap component 28.
Fourth Embodiment
[0066] In the embodiment of FIGS. 9 and 10 the cap 2 is made of an
annular cap component 28 and a circular valve plate 60 formed in
the shape of a circular plate 62 that carries the valve 20. The
foil liner 30 sits on top of the plate 60.
[0067] The component 28 has a top panel 86 that defines a central
hole or opening 88 that has a diameter smaller than the diameter of
the plate 62. The cap 2 is part-assembled prior to fitting to the
spout or neck of the container or bottle. As shown in FIG. 9, the
plate 60 is fitted to the component 80 and held in place towards
the base of the cap 2. This can be achieved by resting on an
inwardly facing flange (not shown).
[0068] As the plate 60 is at the base of the cap component 28 when
the cap is fitted there is no significant volume of air that is
entrained when the cap 2 is fitted to the neck of a container or
bottle. As the cap 2 is screwed onto the neck the plate 60 moves
upwards in relation to the skirt component 28. When the plate 60
abuts the top panel 86 the foil 30 trapped against the panel 86.
The cap is induction heated to embed the foil between the plate 62
and the top panel 86 as shown in FIG. 10.
Variations
[0069] As shown in FIGS. 11a to 11c the foil 30 may be fitted over
an open-end face of the valve 20 on the base of the plate 74. In
FIG. 11a, the edge of the foil 32 fits between the valve 20 and a
sacrificial wall 50. Induction heating causes the material of the
sacrificial wall 50 to flow over the edge 32 embedding it in the
material of the valve plate 60. In FIGS. 11b and 11c the foil
extends out to the edge of the valve plate 62 or may be wrapped
round it.
[0070] These variations further reduce the amount of oxygen
entrained when the cap 2 is assembled to the neck as the small
amount trapped in the space defined by the valve 20 is also
eliminated.
Fifth Embodiment
[0071] In the embodiment of FIGS. 12 and 13 the recess 48 is
located on an external surface 70 of the top panel 4 and is
surrounded by a protruding sacrificial wall 50. The foil disc 30 is
dropped into the recess 48 and then heated by induction. The
contact between the edge 32 of the foil and the sacrificial wall 50
causes the material of the wall to flow over the edge sealing the
disc 30 securely to the top 70 of the cap so that it cannot be
removed. The use of a gas barrier on top of the cap allows the foil
30 to cover an even larger portion of the surface. This means that
any gas that is to pass through the cap must pass along a tortuous
and long path within the plastic of the cap to avoid the foil. This
results in very low levels of gas transmission.
[0072] While embedment of the edge 32 is not essential in this
embodiment for avoiding contamination of the contents, the foil
liner 30 must be welded to the top panel 4. Fusing of the entire
foil disc to the panel will prevent the foil being removed during
transport.
Sixth and Seventh Embodiments
[0073] In the embodiments of FIGS. 14 and 15, a large plug 92 fills
nearly all of an internal space within the cap 2. This plug 92 also
forms in its upper part the valve 20 for sealing against an
internal surface of the neck of the bottle or container to which
the cap is fitted.
[0074] In FIG. 14 the cap component 28 is moulded to create a deep
recess 90 in the top panel 4. The valve 20 is formed by an upper
portion of side walls of the recess. A lower part of the plug 92
can have a reduced diameter relative to the valve to aid insertion.
The plug could also be tapered.
[0075] The foil 30 is seated in a recess 48 formed in the top panel
4 and is embedded as described in relation to the earlier
embodiments of FIGS. 12 and 13. The welding of the foil 30 to the
cap component 28 is carried out in a nitrogen environment so that
the recess 90 is filled with this inert gas.
[0076] It will be appreciated that a cap component 28 having a plug
92 cannot be moulded in one piece with a flat top panel. It is
unacceptable to leave the recess exposed as it would attract dirt
and become contaminated. Closing it by means of the foil disc 30,
which seals in the nitrogen atmosphere, provides an elegant
solution to this problem. Moreover, the foil liner 30 is not
directly exposed to the pressure of the contents of the container
but is supported by the plug structure. It is therefore possible to
use a lightweight, flexible aluminium foil for this purpose, as it
is not under pressure.
[0077] In the embodiment of FIG. 15, the foil 30 forms a closure
for an open end of the plug 92 and is embedded and fused into the
valve wall by means of a sacrificial wall 50 which depends
downwardly from the valve wall 20 to provide a slot into which the
edge 32 of the foil can fit prior to being fused into the slot by
means of induction heat sealing. The void inside the plug 92 is
filled with nitrogen or other inert atmosphere.
[0078] In both these embodiments the application of the cap to the
bottleneck introduces the smallest possible amount of entrained
air. Therefore this cap retains as much as possible of the inert
atmosphere in the neck space above the contents as is possible.
Variations
[0079] Rather than simply extending across a top of the deep recess
90 the foil 30 may be used to line the recess 90. The recess may be
left empty, but is preferably filled with other decorative material
to avoid trapping dirt and representing a hygiene risk.
Alternatively a foil may be placed across the deep recess 90 and
the interior lined with EVOH or other similar gas barrier plastics
materials.
General Variations
[0080] Scavenger chemicals may be added to the material of which
the cap is moulded or added to the foil membrane or a scavenger
coating may be applied to the inner surface of the cap 2. It is
also desirable to use oxygen scavenger materials in the parts of
the cap touching or close to the product for example on an internal
end surface of the plug 92.
[0081] It will be appreciated that the constructions described
allow the production of a cap with an effective gas barrier that
also has a functional long valve 20 suitable for sealing carbonated
beverages.
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