U.S. patent application number 13/510881 was filed with the patent office on 2012-12-13 for pressure sealing method for headspace modification.
Invention is credited to David Murray Melrose.
Application Number | 20120311966 13/510881 |
Document ID | / |
Family ID | 44059814 |
Filed Date | 2012-12-13 |
United States Patent
Application |
20120311966 |
Kind Code |
A1 |
Melrose; David Murray |
December 13, 2012 |
PRESSURE SEALING METHOD FOR HEADSPACE MODIFICATION
Abstract
A container cap (80) positioned within a sealing chamber (84)
has an openable aperture to allow the increase in pressure in the
container headspace (231) before the aperture is resealed. In
alternative embodiments the container (1) may include vacuum
compensation panels (801, 802,803, 804) in its sidewall and/or
base.
Inventors: |
Melrose; David Murray; (Mt.
Eden, NZ) |
Family ID: |
44059814 |
Appl. No.: |
13/510881 |
Filed: |
November 17, 2010 |
PCT Filed: |
November 17, 2010 |
PCT NO: |
PCT/NZ2010/000231 |
371 Date: |
May 18, 2012 |
Current U.S.
Class: |
53/403 ; 220/200;
220/601; 53/266.1 |
Current CPC
Class: |
B67B 3/00 20130101; B65B
31/006 20130101; B65D 79/005 20130101; B67C 2003/226 20130101; B65D
71/0088 20130101; B65D 81/2053 20130101 |
Class at
Publication: |
53/403 ;
53/266.1; 220/200; 220/601 |
International
Class: |
B65B 31/00 20060101
B65B031/00; B65D 51/00 20060101 B65D051/00; B65D 6/40 20060101
B65D006/40; B65B 1/00 20060101 B65B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2009 |
NZ |
581313 |
Claims
1-12. (canceled)
13. A sealing machine apparatus for pressurizing the headspace of a
filled container while applying a seal, comprising: an apparatus
for receiving a plurality of containers; a pressure chamber
apparatus connected to a surface or sealing member for engaging a
surface on the container or on a cap provided for the container; a
source of pressure or dosing system coupled to said pressure
chamber for raising the pressure within said pressure chamber and
said containers; apparatus for moving the sealing member or surface
into engagement with the surface on the container or cap; said
pressure chamber surrounding a container sealing apparatus for
applying a seal or said cap to at least one of said containers;
said container sealing apparatus moving to seal said container
within the pressure chamber while the pressure chamber is subjected
to a raised internal pressure to create an increased pressure
within the sealed container.
14. An apparatus as claimed in claim 13, wherein said sealing
machine is a capping machine, and said seals are said caps or are
closures.
15. An apparatus as claimed in claim 13, wherein said containers
are filled with a heated liquid.
16. An apparatus as claimed in claim 13, wherein said sealing
machine is a rotary device driven by a rotatable driven turret.
17. An apparatus as claimed in claim 16, wherein said containers
are moved about in a generally circular path by said turret.
18. An apparatus as claimed in claim 13, wherein said pressure
chamber provides temporary sealing of said containers adjacent a
neck finish of said containers.
19. An apparatus as claimed in claim 18, wherein said container
sealing apparatus or said pressure chamber provides temporary
sealing of said containers at or adjacent a neck support ring of
said neck finish.
20. An apparatus as claimed in claim 13, wherein said container
sealing apparatus is a holding apparatus for holding the cap in
position to engage a finish of the container.
21. An apparatus as claimed in claim 13, wherein said container
sealing apparatus provides capping torque to close the
container.
22. An apparatus as claimed in claim 13, wherein said source of
pressure or dosing system provides at least one liquid and/or
gas.
23. An apparatus as claimed in claim 22, wherein at least one said
liquid and/or gas is steam, air, nitrogen, or carbon dioxide.
24. An apparatus as claimed in claim 13, wherein said containers
are for use in hot or cold filling operations each having a said
seal or said cap adapted to provide a temporary opening or aperture
into said container, said opening or aperture providing for the
introduction under pressure of one or more liquids and/or gases,
said seal or cap providing with a neck of said container, in use, a
container headspace having a pressure, at the moment of sealing,
substantially greater than existed prior to introduction of said
one or more liquids and/or gases.
25. An apparatus as claimed in claim 24 further including at least
one vacuum compensation element in a sidewall of the container.
26. An apparatus as claimed in claim 24 or claim 25 including at
least one vacuum compensation element in a base of the
container.
27. An apparatus as claimed in claim 24 including at least one
expandable element in a sidewall of the container.
28. An apparatus as claimed in claim 24 or claim 27 including at
least one expandable element in a base of the container.
29. An apparatus as claimed in claim 24 wherein said greater
pressure, substantially at the moment of sealing, is positive.
30. An apparatus as claimed in claim 24 for hot filling wherein,
after hot filling, the greater pressure compensates for a pressure
reduction on cooling of the contents of the container.
31. An apparatus as claimed in claim 24 wherein said seal or cap is
adapted to provide said opening or aperture after said seal or cap
has been applied to the neck.
32. An apparatus as claimed in claim 24 wherein said seal or cap is
adapted to be pierced to provide said opening or aperture and
expose the container headspace to ambient pressure.
33. A cap for a container, the cap being adapted for use with the
apparatus of claim 13.
34. A system for filling a container with a fluid including
introducing the fluid through an open end of the container,
providing a seal or cap, providing a sealing chamber enclosing an
opening or aperture between said seal or cap and said container
interior, increasing the pressure within the sealing chamber by
introducing at least one liquid and/or gas through the opening or
aperture to create an increased pressure within the headspace of
the container, sealing the opening or aperture within the sealing
chamber under the increased pressure conditions.
35. A system for filling a container as claimed in claim 34, in
which the fluid is heated before or after its introduction into the
container, and said system compensates for subsequent pressure
reduction in a headspace of the container under the seal or cap
following the cooling of the heated contents.
36. A system as claimed in claim 34 in which the at least one
liquid and/or gas passes through the opening or aperture under
pressure.
37. A system as claimed in claim 34 in which the container is
positioned in a pressurizing area.
38. A system as claimed in claim 34 in which the at least one
liquid and/or gas is a heated liquid or steam injected through the
opening or aperture.
39. A system as claimed in claim 34 in which the opening or
aperture is provided with a temporary or partial seal through which
the at least one liquid and/or gas is provided.
40. A system as claimed in claim 35 including conveying said sealed
or capped containers prior to the pressure chamber, and creating
and/or providing said opening or aperture within the pressure
chamber.
41. A system as claimed in claim 40 in which the opening or
aperture provided within said seal or cap is provided with a
temporary or partial seal for at least a period of time prior to
conveyance into said pressure chamber.
42. A system as claimed in claim 41 in which said seal or cap has a
liner material on an inside surface, said liner temporarily sealing
the opening or aperture.
43. A system as claimed in claim 40 in which the opening or
aperture is sealed under elevated pressure conditions.
44. A system as claimed in claim 34 or 40, wherein said container
includes at least one moveable pressure panel in a sidewall of said
container.
45. A system as claimed in claim 40, wherein said container
includes at least one moveable pressure panel in a base of said
container.
46. A container when filled by the system of claim 40.
47. A method of filling and processing a container with a fluid
including: introducing the fluid through an open end of the
container so that it, at least substantially, fills the container,
applying a seal or cap to said container, transporting or conveying
said container, creating and/or providing an opening or aperture in
said seal or cap, providing a method of introducing at least one
liquid and/or gas through the opening or aperture at a pressure
greater than within said container prior to providing said opening
or aperture, providing a method of sealing the opening or
aperture.
48. A method as claimed in claim 47 wherein said seal or cap is
subjected to at least partial sterilization treatment prior to the
provision of said opening or aperture.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates generally to a method of
light-weighting containers by modifying the pressure in the
headspace and a container utilising that method. The pressure
modification may be undertaken either during the sealing of the
container, or after sealing the container. This headspace
modification may be achieved by filling a container with a liquid,
sealing the contents of the container from contamination from
outside air, and adjusting the pressure of the headspace either
during the capping process or after the container has been capped
or sealed. The headspace modification process increases the volume
of content within the container, thereby increasing the internal
pressure within the container. This action in turn may displace the
liquid below the headspace in the upper neck region of the
container downwardly prior to or after capping of the container,
providing for increased top-load capability for the container. This
invention may further relate to hot-filled and pasteurized products
packaged in heat-set polyester containers.
BACKGROUND
[0002] Most production facilities are searching for ways to reduce
costs as a small savings on the cost of each single container, for
a food or beverage packer, this quickly adds up to tremendous
savings, based on the large number of containers processed.
Utilizing lighter weight containers or reducing utility costs are
good savings methods.
[0003] However, lighter weight containers for noncarbonated
products can collapse when stacked unless special handling
requirements are satisfied. One typical method used to increase
stacked weight capability, or top-load strength, in cold fill
containers is to dose the container with liquid nitrogen prior to
capping. When dosed into a container, liquid nitrogen will provide
some internal pressure, which allows the containers to be stacked
several pallets high. Gaseous nitrogen is one utility used in the
food and beverage industry to expel oxygen from products and
increase shelf life.
[0004] However, as the nitrogen disperses immediately upon
injection the process for controlling accurate dosing is limited.
Some of the nitrogen will escape prior to capping, thus rendering
the process inexact in terms of absolute pressurisation control.
Additionally, handling nitrogen systems can be costly and
dangerous.
[0005] Nitrogen consumption can be reduced by as much as 80% using
a liquid nitrogen dosing system instead of gaseous nitrogen
tunnels, but as the capping or sealing of the container occurs at
ambient pressure at the precise time of sealing, in both systems,
the resulting pressure value is compromised. At the instantaneous
moment of sealing, the pressure value can only be equal to ambient
pressure. Following capping there is a subsequent rise in internal
pressure as the nitrogen continues to expand but cannot escape the
sealed container. However, as the nitrogen is dosed prior to
sealing there is a loss of some of the nitrogen dose prior to
sealing, the amount of which varies according to many factors. This
leaves the process inexact in terms of identifying the dose
actually in the container after sealing. It is accepted that this
will always be a value less than the dose introduced to the open
container prior to sealing.
[0006] Because air is composed of 78% nitrogen by volume, nitrogen
is abundant. Liquid nitrogen has a boiling point of -320.degree. F.
(-196.degree. C.) at atmospheric pressure. Handling liquid nitrogen
when pressurizing or inerting food and beverage containers on a
production line poses challenges. To use liquid nitrogen injection,
a production facility must have a storage vessel, liquid nitrogen
piping and an injection device capable of metering small amounts of
liquid nitrogen accurately and consistently. To store, transfer or
inject liquid nitrogen, insulated equipment is a necessity because
liquid nitrogen will boil away rapidly when exposed to room
temperatures.
[0007] The use of nitrogen, however, does provide for a build-up of
internal pressure within a container following capping. This is
more practical in the case of beverages filled into the container
cold, than when used in conjunction with hot fill beverages. In
both cases it is possible that all dosed nitrogen disperses prior
to sealing the container, for example if there is a stoppage on the
line post dosing and prior to capping. However, in a cold filled
application the result would be a container that at least is capped
at ambient pressure and will remain at ambient pressure. While the
benefit of increased top load and sidewall strength would be lost,
the result is not particularly damaging as the container would
still look attractive to the consumer when purchased. In the case
of a hot filled beverage, however, an insufficient dose results in
the container being sealed at ambient pressure and possessing
little ability to pressurize the container following sealing. As
the liquid contents of the container subsequently cool and contract
a vacuum will build and the container will distort as a result.
This is not attractive for the consumer. Additionally, the dosing
process becomes even more difficult to control in the hot fill
environment, particularly at fast line speeds. When nitrogen is
introduced into a container under ambient pressure conditions and
on top of a heated liquid, the nitrogen will be much more volatile
than if the liquid is cold. It will disperse much more quickly
prior to capping or sealing leaving the consistency of dose, much
more uncertain. A stoppage in the line is therefore more damaging
to consistency of dose. For this reason, containers are often
overdosed as a precautionary measure, and this is still not
ideal.
[0008] Plastic bottles need to be pressurized at all line speeds,
and if control over the exact pressure achieved inside a container
is compromised then the speed of the system will also be
compromised in order to correctly pressurise each container.
[0009] Food and beverage plant personnel are required to consider a
number of goals and criteria when selecting a liquid nitrogen
system, including: [0010] Consistent container pressures or
consistent oxygen reduction. [0011] Plant personnel safety. [0012]
Reliable system operation. [0013] Reasonable acquisition and
operating costs.
[0014] Each producer has different priorities for each goal, but
safety usually is high on the list. It is important to remember
that liquid nitrogen becomes a gas at room temperature and expands
to 700 times its volume as a liquid. Adequate piping system and
injection equipment protection, including safety relief valves,
must be used to prevent over-pressurization or equipment rupture. A
safety relief valve must be placed between any two shutoff valves
in the system. On bulk tank-fed systems, the lowest rated relief
device typically is placed outdoors. If a safety relief valve does
relieve, it is safer if it happens outdoors rather than inside
where someone could get hurt.
[0015] Reliability is important on a production line where losses
are calculated in minutes of downtime. A liquid nitrogen dosing
device will need some startup time from a room temperature
condition because all internal surfaces must be cooled down to
liquid nitrogen temperatures. As with any liquid nitrogen
equipment, operating procedures must be adhered to because the
danger of contaminating the equipment with moisture does exist.
Moisture is the biggest enemy of the cold surfaces of liquid
nitrogen equipment. It takes only a small amount to freeze up the
equipment internally. Equipment adjustments such as nozzle changes
for different container sizes and maintenance must be able to be
completed without moisture contamination or long downtimes. Each
production facility has different specifications for liquid
nitrogen delivery. Some applications require that the liquid
nitrogen be delivered aseptically. In such a case, the dosing unit
also must be capable of being sterilized.
[0016] Consistent pressurizing or inerting results are important to
the entire operation. A water bottle with too little pressure could
collapse when stacked or not labelled properly. A bottle with too
much pressure possibly could burst when stored in the trunk of a
car due to temperature effects. Inerted products could oxidize or
spoil if the liquid nitrogen dose was too small; too large a dose
on an inerted product could cause an over-pressurized container to
jam the production line. Nitrogen injection can be accomplished by
dosing individual containers or with a steady stream of liquid
nitrogen. Either method can yield consistent results.
[0017] Liquid nitrogen will boil away rapidly once it is introduced
into a container. Therefore, it is important to control the liquid
nitrogen efficiently before dosing. A typical 18 fl oz (600 ml)
polyethylene terephthalate (PET) bottle with a 1 fl oz (30 ml)
headspace and pressure specification of 17 psig will need
approximately 0.001411 oz (0.04 g) of liquid nitrogen. The dose of
liquid nitrogen will boil away and expand to 1.163 fl oz (34.4 ml)
of room temperature nitrogen gas after the container is sealed. Add
1.163 fl oz of gas to a sealed volume of 1 fl oz, and you end up
with 17 psig.
[0018] The challenge for the liquid nitrogen dosing equipment
manufacturer is to control the boiling liquid and deliver the
0.001411 oz consistently at speeds from 40 bottles/min to more than
1,000 bottles/min. The dosing equipment can control the liquid
nitrogen up to the dosing point, but it cannot control the liquid
nitrogen's behavior once it has been dosed into the container. The
liquid nitrogen will boil away rapidly as the container travels to
the capper or seamer, so travel time should be minimized for
accurate results. The transfer from dosing to capping also should
be smooth to prevent the boiling liquid from bouncing out of the
container.
[0019] Another aspect to consider is consistent container fill
levels. If container headspace varies because the fill levels are
wildly different, the final bottle pressures also will be wildly
different. For example, suppose the bottle previously mentioned had
an 18 fl oz fill with a 1 fl oz headspace, and the next bottle on
the production line had a fill of 18.3 fl oz (610 ml) with a 0.6 fl
oz (20 ml) headspace. Both bottles receive a 0.001411 oz charge of
liquid nitrogen. The liquid nitrogen dosing is consistent; however,
in accordance with basic gas laws, the final bottle pressure on the
18 fl oz fill is 17 psig and the bottle with a 18.3 fl oz fill has
25.5 psig final pressure. Many factors determine final bottle
pressure accuracy in addition to the dosing equipment accuracy.
They include container volume consistency and good sealing
closures. All factors must be addressed for good results.
[0020] Costs are a critical concern for manufacturers. It is
important to remember that initial purchase price, installation
expenses and operating costs must be considered jointly. Outside
bulk storage tank vessels are more expensive to obtain than small
portable dewars, but liquid nitrogen costs much less in bulk than
dewars. The changing out process also adds to the hidden cost of
using dewars; a 41.6 gal (160 l) dewar usually will last one 8-hr
shift on a production line.
[0021] Piping is another area where processors try to save money.
Most manufacturers can make a relatively inexpensive foam-insulated
pipe. However, consider how much liquid nitrogen is lost during one
year with a foam insulated pipe. Acquisition and installation costs
are higher for a vacuum-jacketed system, but the reduced loss rate
due to superior insulation makes operating costs lower than with a
foam-insulated system. An inexpensive foam insulated liquid
nitrogen injection device is not a bargain if downtime due to a
frozen dosing device occurs.
[0022] Some dosing devices require a thaw out period of up to 24 hr
after use. Startup and shutdown times also are important factors to
consider when calculating liquid nitrogen injection system
operating costs. When considering liquid nitrogen dosing on a
production line, it is necessary to look at many factors. Initial
cost is only a small part of the puzzle. Most production plants
considering using liquid nitrogen need the proper information and
training to be successful and should consult a liquid nitrogen
dosing equipment-manufacturer before making a final decision.
[0023] The amount of liquified gas added to a container and the
head-space volume above the product filled into the container are
critical elements in determining the resulting internal pressure of
a container upon expansion of the liquified gas. Also, the
temperature of hot filled products affects the internal pressure
after cooling, according to Boyles law.
[0024] Conventionally, the dosage of liquified gas dispensed into a
container is based on an average expected fill level of the
containers in a continuous fill operation. Using this method, any
variation in head-space volume due to variations in fill level
would cause under and over pressurized containers. U.S. Pat. No.
4,662,154 discloses the art of providing a closed loop control
circuit between a liquid nitrogen dispenser and a pressure
detector. The average internal pressure of recently sealed
containers is monitored to adjust the dosage of liquid nitrogen
added to containers being presently dosed. Containers not meeting
the preset pressure range may be rejected.
[0025] Problems of uniform pressurization still remain using this
method due to basing the dosage on the average pressure of already
sealed containers. Whether a given container has a head-space
volume that varies high or low, it will receive a dosage based upon
an average head-space volume of containers previously sealed.
Therefore, the range of container pressures can still vary
widely.
[0026] Additional problems are caused by the fact that container
pressure is the only monitored dosage criteria. Container pressure
is measured after a container has already received a dosage and is
sealed. This after-the-fact detection can result in high spoilage
rates when there are sudden variations in product fill level. These
sudden variations will not be detected until after the containers
are sealed. Even more spoilage may result as the detection and
correction of improper dosages is slow due to the averaging
process. Containers must continue to be incorrectly dosed until the
average values detect fluctuation.
[0027] All of the abovementioned concerns are even greater when
used with hot filling liquids into containers.
[0028] So called `hot fill` containers are well known in prior art,
whereby manufacturers supply PET containers for various liquids
which are filled into the containers and the liquid product is at
an elevated temperature, typically at or around 85 degrees C. (185
degrees F.).
[0029] The container is manufactured to withstand the thermal shock
of holding a heated liquid, resulting in a `heat-set` plastic
container. This thermal shock is a result of either introducing the
liquid hot at filling, or heating the liquid after it is introduced
into the container.
[0030] Once the liquid cools down in a capped container, however,
the volume of the liquid in the container reduces, creating a
vacuum Within the container. This liquid shrinkage results in
vacuum pressures that pull inwardly on the side and end walls of
the container. This in turn leads to deformation in the walls of
plastic bottles if they are not constructed rigidly enough to
resist such force.
[0031] Typically, vacuum pressures have been accommodated by the
use of vacuum panels, which distort inwardly under vacuum pressure.
Prior art reveals many vertically oriented vacuum panels that allow
containers to withstand the rigors of a hot fill procedure. Such
vertically oriented vacuum panels generally lie parallel to the
longitudinal axis of a container and flex inwardly under vacuum
pressure toward this longitudinal axis.
[0032] In addition to the vertically oriented vacuum panels, many
prior art containers also have flexible base regions to provide
additional vacuum compensation. Many prior art containers designed
for hot-filling have various modifications to their end-walls, or
base regions to allow for as much inward flexure as possible to
accommodate at least some of the vacuum pressure generated within
the container.
[0033] Even with such substantial displacement of vacuum panels,
however, the container requires further strengthening to prevent
distortion under the vacuum force.
[0034] The liquid shrinkage derived from liquid cooling, causes a
build up of vacuum pressure. Vacuum panels deflect toward this
negative pressure, to a degree lessening the vacuum force, by
effectively creating a smaller container to better accommodate the
smaller volume of contents. However, this smaller shape is held in
place by the generating vacuum force. The more difficult the
structure is to deflect inwardly, the more vacuum force will be
generated. In prior art proposals, a substantial amount of vacuum
may still be present in the container and this tends to distort the
overall shape unless a large, annular strengthening ring is
provided in horizontal, or transverse, orientation typically at
least a 1/3 of the distance from an end to the container.
[0035] The present invention relates to hot-fill containers and may
be used by way of example in conjunction with the hot fill
containers described in international applications published under
numbers WO 02/18213 and WO 2004/028910 (PCT specifications) which
specifications are also incorporated herein in their entirety where
appropriate.
[0036] The PCT specifications background the design of hot-fill
containers and the problems with such designs that were to be
overcome or at least ameliorated and in particular the use of
pressure compensation elements.
[0037] A problem exists when locating such transversely oriented
panels in the container side-wall, or end-wall or base region, even
after vacuum is removed completely from the container when the
liquid cools down and the panel is inverted. The container exits
the filling line just above a typical ambient temperature, and the
panel is inverted to achieve an ambient pressure within the
container, as opposed to negative pressure as found in prior art.
The container is labelled and often refrigerated at point of
sale.
[0038] This refrigeration provides further product contraction and
in containers with very little sidewall structure, so-called `glass
look-a-like` bottles, there may therefore be some panelling that
occurs on the containers that is unsightly. To overcome this, an
attempt is made to provide the base transverse panel with more
extraction potential than is required, so that it may be forced
into inversion against the force of the small headspace present
during filling. This creates a small positive pressure at fill
time, and this positive pressure provides some relief to the
situation. As further cool down occurs, for example during
refrigeration, the positive pressure may drop and may provide for
an ambient pressure at refrigerated temperatures, and so avoid
panelling in the container.
[0039] This situation is very hard to engineer successfully,
however, as it depends on utilising a larger headspace in order to
compress at base inversion time, and it is less desirable to
introduce a larger headspace to the container than is necessary in
order to retain product quality.
[0040] While it is desirable to have the liquid level in the
container drop, to avoid spill when opened by the consumer, it has
been found that providing too much positive pressure potential
within the base may cause some product spill when the container is
opened, particularly if at ambient temperatures.
[0041] In most filling operations, containers are generally filled
to a level just below the containers highest level, at the top of
the neck finish.
[0042] Maintaining as small a container headspace as possible is
desirable in order to provide a tolerance for subtle differences in
product density or container capacity, to minimize waste from
spillage and overflow of liquids on a high-speed package filling
line, and to reduce container contraction from cooling contents
after hot fill.
[0043] Headspace contains gases that in time can damage some
products or place extra demands on container structural integrity.
Examples include products sensitive to oxygen and products filled
and sealed at elevated temperatures.
[0044] Filling and sealing a rigid container at elevated
temperatures can create significant vacuum forces when excessive
headspace gas is also present.
[0045] Accordingly, less headspace gas is desirable with containers
filled at elevated temperatures, to reduce vacuum forces acting on
the container that could compromise structural integrity, induce
container stresses, or significantly distort container shape. This
is also true during pasteurization and retort processes, which
involve filling the container first, sealing, and then subjecting
the package to elevated temperatures for a sustained period.
[0046] Those skilled in the art are aware of several container
manufacturing heat-set processes for improving package
heat-resistant performance. In the case of the polyester,
polyethylene terephthalate, for example, the heat-setting process
generally involves relieving stresses created in the container
during its manufacture and to improve crystalline structure.
[0047] Typically, a polyethylene terephthalate container intended
for a cold-fill carbonated beverage has higher internal stresses
and less crystalline molecular structure than a container intended
for a hot-fill, pasteurized, or retort product application.
However, even with containers such as described in the
abovementioned PCT specifications where there is little residual
vacuum pressure, the neck finish of the container is still required
to be very thick in order to withstand the temperature of fill.
[0048] My PCT patent specification WO 2005/085082 describes a
previous proposal for a headspace displacement method which is
incorporated herein in its entirety where appropriate by way of
reference.
[0049] Where reference in this specification is made to any prior
art this is not an acknowledgment that it forms part of the common
general knowledge in any country or region.
OBJECTS OF THE INVENTION
[0050] In view of the above, it is an object of one possible
embodiment of the present invention to provide a container and
contents combination having an increased pressure within an
unsealed container whereby the volume of the contents combination
exceeds the volume of the as-moulded container, said container
having an increased pressure when subsequently sealed or
capped.
[0051] It is a further object of one possible embodiment of the
present invention to provide a container, cap and contents
combination that provides for an increased pressure within a sealed
container whereby the volume of the contents combination is larger
than the contents combination initially filled and sealed within
the container, when the contents combination is held at the
temperature used at the time of filling and sealing the
container.
[0052] It is a further object of the present invention to force
additional contents into the container under controlled pressure to
reinforce the sidewalls.
[0053] In view of the above, it is an object of one possible
embodiment of the present invention to provide a pressure sealing
method and headspace modification method that can provide for
increased pressure within the sealed container such that there is
increased top load capability.
[0054] It is a further object of one possible embodiment of the
present invention to provide a pressure sealing method and
headspace modification method that can provide for increased
pressure within the sealed container such that there is increased
top load capability, utilising a gas other than nitrogen such as
simple clean or filtered air.
[0055] It is a further object of one possible embodiment of the
present invention to provide a pressure sealing method and
headspace modification method that can provide for removal of
vacuum pressure such that there is substantially no remaining force
within the container utilising a gas other than nitrogen, such as
simple clean or filtered air.
[0056] It is a further object of one possible embodiment of the
present invention to provide a pressure sealing method and
headspace modification method that can provide for removal of
vacuum pressure such that there is substantially no remaining force
within the container utilising a simple heated liquid such as
water.
[0057] It is a further object of one possible embodiment of the
present invention to provide a headspace compression method whereby
air, or some other gas or liquid or combination thereof, is charged
into the headspace under sealed pressure to create an increased
pressure in order to negate the effect of vacuum pressure created
during cooling of the product.
[0058] It is a further object of one possible embodiment of the
present invention to provide a headspace modification method
whereby sterile or heated liquid, or air, or some other gas or
combination thereof, is charged into the headspace under sterile
conditions to create a positive pressure in order to negate the
effect of vacuum pressure created during cooling of the
product.
[0059] It is a further object of one possible embodiment of the
present invention to provide a headspace modification method
whereby sterile air, or some other gas or liquid or combination
thereof, is charged into the headspace under sealed pressure to
negate the effect of vacuum pressure created during cooling of the
product.
[0060] It is a further object of one possible embodiment of the
present invention to provide a headspace modification method
whereby a compressive seal is applied to the neck finish of the
container.
[0061] It is a further object of one possible embodiment of the
present invention to provide a headspace displacement method
whereby a compressive seal is applied to the neck finish that is
forcibly displaceable into the container prior to cooling the
liquid contents, such that a positive pressure may be induced into
the container.
[0062] A further and alternative object of the present invention in
all its embodiments, all the objects to be read disjunctively, is
to at least provide the public with a useful choice.
SUMMARY OF THE INVENTION
[0063] The pressure sealing method of the present invention may
provide for the seal of a container to be finally closed within an
increased pressure environment rather than at ambient pressure. In
this way an exact pressure can be achieved within the container at
the moment of sealing, ensuring consistency of headspace pressure
in every container. This prevents any variability caused by
inconsistent timing of bottle presentation to a capper,
inconsistent fill levels within a container, inconsistent container
sizes and so forth.
[0064] The present invention may improve upon dosing techniques for
expanding gases such as nitrogen, by ensuring the seal is finalised
only when the correct dose is applied inside the container.
[0065] The present invention may also provide for the use of
non-expanding gases to be used, such as air, filtered air, steam or
other inert gas.
[0066] The present invention may also provide for fluid or liquid
to be introduced under pressure into the headspace of a container
as opposed to expanding or non-expanding gas. The liquid may be
either, heated and contractible or heatable and
non-contractable.
[0067] The present invention may be suitable for cold filled and
aseptic filling lines as a way of controlling nitrogen dosing into
containers for increased top load to ensure consistent dose
application.
[0068] The present invention may be suitable for cold filled and
aseptic filling lines as a way of increasing top load in containers
but avoiding the use of nitrogen by instead increasing the pressure
within containers through the introduction of some other medium,
for example filtered air or water, which may be sterile and/or
heated and/or cold.
[0069] The present invention may provide for the pressure to be
increased within the container immediately prior to and during
capping.
[0070] The present invention may provide for the pressure
re-sealing of a container that has been initially sealed in a
conventional, ambient pressure manner.
[0071] The present invention may provide for pressurisation of the
container to provide compensation for any cooling of heated
contents within the container, either before or after the contents
have cooled.
[0072] The pressure sealing method of the present invention may
provide for on-line gaseous or liquid dosage calibration in a
conventional container filling line. The amount of pressure within
the headspace may be controlled precisely at the time of sealing
and may be readily adjusted to deliver consistent dosage to each
container which corresponds to the container's individually
measured head-space volume.
[0073] The system may generally include an empty container in-feed
station, a continuous container conveying system, a container
product fill station, a container head-space dosing station, an
optional liquified gas dispensing station, an optional gas
dispensing station, an optional liquid dispensing station, a
container sealing station, a container internal pressure sensing
station, a discharge conveyor and a reject apparatus.
[0074] One preferred embodiment of the present invention may
provide for the container sealing station to incorporate the
optional gas, liquefied gas, liquid and container internal pressure
sensing stations.
[0075] The system may provide for the on-line control of the
head-space volume of each container after it has been filled with
product and following the addition of liquid or gas. The head-space
volume measurement may be precisely controlled at the time of
sealing so that the dosage of liquid or gas delivered to each
container may correspond directly to its individually measured
head-space, and generally does not alter once immediately sealed,
except for variations caused by temperature changes within the
contained liquid.
[0076] With dosages being exactly correlated to the individually
measured requirements of each container, very uniform pressure
ranges may be obtained opposed to dosages based on expected fill
levels or after-the-fact average measurements. Therefore,
containers can be down gauged as they will not be required to
accommodate a wide pressure range. Furthermore, the system may
achieve lower spoilage rates due to improperly pressurized
containers because the system immediately self adjusts for fill
variations as containers receive a dosage of liquid or gas.
[0077] A particular advantage of the present method and system may
be the greater and more precise control allows for much lower
pressure dosing for hot fill containers. In prior methods a minimum
pressure value can only be assured by over pressurisation on
average, such that the lowest dose achieved will meet
specifications. This has resulted in generally high pressures
achieved during the early stages of hot fill, when the container is
hot and malleable. As a result the container is stressed
significantly in most occasions, necessitating the need for example
for petaloid bases and container designs more suitable to
carbonated or pressure vessels. This reduces significantly the
design options available for containers, and requires additional
weight in the container surrounding the base in order to achieve
reasonable results.
[0078] Other advantages and aspects of the invention will become
apparent upon making reference to the specification, claims, and
drawings to follow.
[0079] According to one aspect of the present invention there is
provided a container for use in hot or cold filling operations and
having a seal or cap adapted to provide a temporary opening or
aperture into said container, said opening or aperture providing
for the introduction under pressure of one or more liquids and/or
gases, said seal or cap providing with a neck of said container, in
use, a container headspace having a pressure, substantially at the
moment of sealing, greater than existed prior to introduction of
said one or more liquids and/or gases.
[0080] According to a further aspect of the present invention there
is provided an expandable container having a seal or cap that is
applied to the container under an increased pressure environment
such that the container headspace has a positive pressure value
substantially at the exact moment of sealing to provide for
increased pressure inside the container.
[0081] According to a further aspect of the present invention there
is provided a container having a seal or cap that is applied to the
container under an increased pressure environment such that the
container headspace has a positive pressure value substantially at
the exact moment of sealing to provide for increased pressure
inside the container to negate the effects of a subsequent cooling
of a liquid that is heated either before or after filling into the
container.
[0082] According to a further aspect of the present invention there
is provided a container having a seal or cap that is finally closed
on a container under a controlled environment such that the
container headspace has a controlled pressure value substantially
at the exact moment of sealing to provide for increased pressure
inside the container to negate the effects of a cooling of a liquid
that is heated either before or after filling into the
container.
[0083] According to a further aspect of the present invention there
is provided a capping unit that seals the open end of a container
from the outside environment and applies pressure to the inside of
the container prior to and during application of a cap or seal such
that the container headspace has a positive pressure value
substantially at the exact moment of sealing to provide for
increased pressure inside the container.
[0084] According to a further aspect of the present invention there
is provided a capping unit that seals the open end of a container
from the outside environment and applies pressure to the inside of
the container prior to and during application of a cap or seal such
that the container headspace has a positive pressure value
substantially at the exact moment of sealing to provide for
increased pressure inside the container to negate the effects of a
subsequent cooling of a liquid that is heated either before or
after filling into the container.
[0085] According to a further aspect of the present invention there
is provided a container having a seal or cap having a temporary
opening or aperture into said container, said aperture providing
for the introduction under pressure of a gas, or liquid or both,
said aperture also being sealable under compression to provide a
controlled raising of internal pressure within the container prior
to cooling of the heated contents.
[0086] According to a further aspect of the present invention there
is provided a container having a seal or cap temporarily applied
such that an opening or aperture into said container is provided by
an incomplete seal being formed between the cap and the neck finish
of the container, said aperture providing for the introduction
under pressure of a gas, or liquid or both, said aperture also
being sealable under torque compression to provide a controlled
raising of internal pressure within the container prior to cooling
of the heated contents.
[0087] According to a further aspect of the present invention there
is provided a container having a seal or cap providing a temporary
seal immediately post-filling and an aperture or opening being
accessible under sterile conditions to provide for the introduction
of a heated or sterile gas, or liquid or both, said aperture or
opening also further being sealable under sterile conditions to
provide a controlled raising of internal pressure within the
container following cooling of the heated contents.
[0088] According to a further aspect of the invention a method of
filling a container with a liquid includes introducing the liquid
through an open end of the container, providing a seal or cap
having, or adapted to have, an opening or aperture, providing at
least one gas and/or liquid through the opening or aperture and
sealing the opening or aperture to increase the pressure in a
headspace of the container.
[0089] According to a further aspect of the invention a method of
filling a container with a fluid includes introducing the fluid
through an open end of the container so that it, at least
substantially, fills the container, heating the fluid before or
after its introduction into the container, providing a seal or cap
having an opening or aperture, said opening or aperture being
initially sealed, providing for the heated contents to cool,
providing a method of subsequently accessing the opening or
aperture under controlled conditions and injecting gas and/or
liquid through the opening or aperture and sealing the opening or
aperture under controlled conditions, so as to compensate for the
pressure reduction in the headspace of the container following the
cooling of the heated contents.
[0090] According to a further aspect of the present invention there
is provided a container having an upper portion with an opening
into said container, said upper portion having a neck finish
adapted to include, subsequent to the introduction of a heated or
heatable liquid into the container, a moveable seal, said seal
being inwardly compressible or mechanically moveable while the
liquid is in a heated state, or prior to heating, so as to increase
the pressure of the headspace.
[0091] According to a further aspect of the invention a method of
filling a container with a fluid includes introducing the fluid
through an open end of the container so that it, at least
substantially, fills the container, heating the fluid before or
after its introduction into the container, providing a moveable
seal for the open end to cover and contain the fluid, said seal
being capable of mechanical compression of the headspace of the
container so as to compensate for subsequent pressure reduction in
a headspace of the container under the seal as the heated contents
are cooled.
[0092] According to a further aspect of the invention a method of
sealing a container with a gas or liquid includes capping the
container with the entire capping station being pressurised.
[0093] Further aspects of the invention which should be considered
in all its novel aspects will become apparent from the following
description.
BRIEF DESCRIPTION OF DRAWINGS
[0094] FIGS. 1a-b: show a container according to one embodiment of
a Prior Art invention with a mechanically compressible cap applied
to seal the beverage;
[0095] FIGS. 2a-b: shows a container according to a further
embodiment of a Prior Art invention with a mechanically
compressible cap applied to seal the beverage;
[0096] FIGS. 3a-b: show part cross-sectional view of an alternative
embodiment of the compressed cap of FIGS. 1 and 2;
[0097] FIGS. 4a-b: show a container according to a one embodiment
of the invention with an enlarged view of a cap including a
sealable aperture;
[0098] FIG. 5a-c: show enlarged views of one possible embodiment of
the cap of FIGS. 4a-b;
[0099] FIG. 6a-c: show one embodiment of enclosing the cap of FIGS.
5 with a pressure application device;
[0100] FIGS. 7a-c: show one embodiment of a cap-sealing device
suitable for use in the pressure application device of FIGS. 6;
[0101] FIGS. 8a-c: show the embodiment of cap-sealing device of
FIGS. 7 closing the cap while under compression;
[0102] FIGS. 9a-c: show withdrawal of the cap-sealing device of
FIGS. 8 following sealing and subsequent decompression of the
compression chamber;
[0103] FIGS. 10a-c: show the container cap of FIGS. 9 following
release from the compression chamber (container not shown
fully);
[0104] FIG. 11a-c: show enlarged views of a further embodiment of
the cap of FIGS. 4a-b;
[0105] FIGS. 12a-c: show one embodiment of a cap-sealing device
suitable for use in the sterilising application device of FIGS.
11;
[0106] FIGS. 13a-c: show one embodiment of cap-sealing device of
FIGS. 12 piercing the cap while under sterilisation;
[0107] FIGS. 14a-c: show withdrawal of the piercing and delivery
device of FIGS. 13 following sterilisation and subsequent pressure
equalisation of the headspace;
[0108] FIGS. 15a-c: show the resealing of the container cap of
FIGS. 14 prior to container release from the sterilisation chamber
(container not shown fully);
[0109] FIGS. 16a-c: show additional views of the cap of FIGS.
12,13,14,15 according to one possible method of headspace
modification;
[0110] FIGS. 17a-c: show a further possible embodiment of this
invention;
[0111] FIGS. 18: shows a further possible embodiment of the
invention using a sealing chamber;
[0112] FIG. 19a-b: show a possible embodiment of the invention in
the form of a capping machine;
[0113] FIG. 20a-b & FIGS. 21a-b: show a further possible
embodiment of the invention using a pressure chamber;
[0114] FIG. 22a-c & FIGS. 23a-c: show diagrammatically a
possible method of the present invention;
[0115] FIGS. 24 to 27: show diagrammatically a further possible
embodiment of the invention in the form of a capping machine;
[0116] FIGS. 28a-d, 29 a-d & FIGS. 30a-b: show further
embodiments of the invention using a sealing chamber;
[0117] FIG. 31: shows diagrammatically a possible capping system;
and
[0118] FIGS. 32a-c; 33a-c 34a-c; 35a-c; 36a-c; and 37a-c: shows
various possible embodiments with alternative forms of vacuum
compensation.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0119] The following description of preferred embodiments is merely
exemplary in nature, and is in no way intended to limit the
invention or its application or uses.
[0120] As discussed above, to accommodate vacuum forces during
cooling of the contents within a heat set container, containers
have typically been provided with a series of vacuum panels around
their sidewalls and an optimized base portion. The vacuum panels
deform inwardly, and the base deforms upwardly, under the influence
of the vacuum forces. This prevents unwanted distortion elsewhere
in the container. However, the container is still subjected to
internal vacuum force. The panels and base merely provide a
suitably resistant structure against that force. The more resistant
the structure the more vacuum force will be present. Additionally,
end users can feel the vacuum panels when holding the
containers.
[0121] Typically at a bottling plant the containers will be filled
with a hot liquid and then capped before being subjected to a
cold-water spray resulting in the formation of a vacuum within the
container that the container structure needs to be able to cope
with. The present invention relates in one embodiment to hot-fill
containers and a method that provides for the substantial removal
or substantial negation of vacuum pressure. This allows much
greater design freedom and light weighting opportunity as there is
no long& any requirement for the structure to be resistant to
vacuum forces that would otherwise mechanically distort the
container.
[0122] As seen in a Prior Art solution in FIGS. 1a to b, when hot
liquid 21 is introduced to a container 1, the liquid occupies a
volume that is defined by a first upper level 3a. Should a
compressive cap 8 be applied immediately post fill to a container
neck 2, then a vacuum builds up in the headspace 23b that is above
the liquid and under the sealing surface 10 of the compressive cap,
the sealing surface being the lower border of the compressible
inner chamber 9 which is engaged with the outer portion of the cap
8. This headspace vacuum is normally only released when the cap is
removed. While the cap 8 remains in place then the vacuum force
remains largely unchanged. If the walls of the container bend or
flex inwardly then the vacuum pressure level may drop to a small
degree.
[0123] Referring to FIGS. 3a-b shows a further embodiment of Prior
Art invention.
[0124] However, as disclosed in the Prior Art as illustrated in
FIGS. 2a-b, mechanical compression of the moveable seal within the
cap structure to achieve a positive pressure occurs only once the
container has cooled. This has the distinct disadvantage of moving
unsterilized wall surfaces of the cap components into communication
with the liquid contents of the container. This contamination can
not be tolerated and so an embodiment of the present invention
provides only for this mechanical compression of the headspace to
occur immediately post application of the cap.
[0125] In this way mechanical compression can achieve a positive
pressure while the contents of the container are in a heated state,
and to subsequently enable the container to be cooled without
panelling. The cap components that enter the container headspace
under compression will be sterilised therefore by the heated
contents prior to cooling. It will be appreciated that many
different structures are envisaged for providing a primary sealing
structure that is forcible downwards to displace the liquid
contents to a large degree. Containers of the 600 ml size for
example will require displacement to the order of 20-30 cc of
liquid. Containers of the 2000 ml range of size will require
displacement to the order of 70 cc of liquid.
[0126] It is envisaged that the cap 8 may be of metal or plastics
and could in alternative embodiments be pushed into the neck of the
container 1 rather than screwed and could be lockable in a required
position.
[0127] The cap 9 may be controllably displaced downwardly by any
suitable mechanical or electrical or other means, or manually.
[0128] The method of the present invention allows many variables in
mechanical compression to be accounted for, but for larger
containers where significant downward displacement would be
required it is envisaged that only some of the compressive force
would be obtained from a compressive cap and, more significantly,
the remainder would be obtained by the methods discussed in the
following disclosure.
[0129] Referring to FIGS. 4a and b, an exemplary embodiment of the
present invention is shown with a cap 80 engaged with the container
neck 2. Figures onward from 4a all refer to upper portions of
containers as similarly shown in FIG. 4a.
[0130] According to a further aspect of the present invention, and
referring to FIGS. 4a and b, and FIGS. 5 a-c, following the
introduction of a liquid, which may be already heated or suitable
for subsequent heating, a cap may be applied including a small
opening or aperture 81. Thus a headspace 23a is contained under the
main cap body 80 and above the fluid level 40 in the container. The
headspace 23a is communicating with the outside air at this stage
and is therefore at ambient pressure and allowing for the fluid
level 40.
[0131] As seen in FIGS. 6a-c, in one embodiment a sealing chamber
84 is applied over the neck finish and cap combination to seal the
liquid from the outside air (the upper, closed end of the structure
84 is not shown). Following the introduction of a compressive force
50, for example by way of injecting air or some other gas, the
increased pressure within the sealing chamber provides for a
subsequent increase in pressure within the headspace 23b and also
forces the fluid level 40 to a lower point due to the subsequent
expansion of the plastic container.
[0132] As an alternative to the injection of gas, a heated liquid
could be injected, for example heated water. This would provide
further advantage, in that the liquid injected would not be subject
to the expansion that would normally occur when injecting gas into
a heated environment. Thus less force would be ultimately applied
to the sidewalls of the container during the early hot-fill
stages.
[0133] Even further, the injected liquid would contract less than a
gas when subsequently cooled. For this reason less liquid is
necessarily required to be injected into the headspace to provide
compensation for the anticipated vacuum forces that would otherwise
occur.
[0134] Now referring to FIGS. 7 a-c (the compressive force not
shown), while pressure is maintained within the sealing chamber 84,
a plug mechanism 82 is moved downwardly from a delivery device 83
towards the aperture 81.
[0135] As can be seen in FIGS. 8 a-c, while pressure is maintained
within the sealing chamber 84, the hole is closed off permanently
by the placement of the plug 82 into the hole 81.
[0136] At this point, and as can be seen in FIGS. 9 a-c, the
headspace 23b is charged under a controlled pressure, dependant on
the amount of gas delivered, and the sealing chamber may provide
for withdrawal of the delivery device 83 following a release of
pressure within the chamber as the container is ejected and
returned to the filling line.
[0137] As shown in FIGS. 10 a-c, as the bottle subsequently travels
down the filling line and is cooled, the headspace 23b expands as
the liquid volume shrinks. The fluid level 40 lowers to a new
position 41 and the pressurised headspace 23b expands and loses
some or all of its pressure as it forms a new headspace 23c.
[0138] Importantly, however, once the contents are cooled there is
no residual vacuum in the container.
[0139] As an alternative, and as shown in FIGS. 10 d-f, the plug 92
may be temporarily attached to the cap, for example by member 91,
during production of the cap. A liquid, as in the example
illustrated, or gas, could be injected in the same manner under
pressure to circumnavigate the plug and enter the container
headspace under pressure, and a rod mechanism 93 is then forced
downwardly to advance the plug 92 into the hole permanently. In
this alternative there is no need to load the rod with multiple
plug mechanisms.
[0140] A further example of such an alternative is provided in FIG.
18. In this embodiment of the invention the cap 80 has a plug 92
temporarily attached by a member (not shown). A sealing chamber 84
encloses the cap and provides an internal sealed chamber headspace
87 through the compression of sealing rings 89 against the upper
surface of the cap. Gas or liquid, or, a combination of both, is
injected into the chamber headspace 87 through an inlet 86 and
through the spaces around the plug into the headspace of the
container. Once the required pressure within the container is
obtained, the push rod 88 is advanced downwardly to force the plug
92 into position within the cap and therefore seal the container
headspace under the required pressure. This provides for a
calculated internal pressure to be achieved precisely at the time
of sealing the container, when the plug is advanced into final
position. This provides for forward compensation of the effects of
subsequent vacuum generated by a cooling of any heated contents
within the container.
[0141] With reference to FIGS. 19a and 19b, the present invention
may be manufactured to function along very similar lines to a
typical capping station on a filling line. A typical capping
machine head unit 101 encapsulates the sealing unit 84 and provides
the function of sealing and pressurising the container through the
cap to seal the container. A typical capping unit may have
optionally already torqued the cap into position, but the container
would remain unsealed due to the presence of a plug being in an
`unplugged` position within the cap and allowing the passage of
liquid or gas between the inside and outside of the container. The
precise moment of sealing the container occurs as the plug is
rammed into position and the headspace within the cap is not at
ambient pressure, as would be typical of prior art capping
procedures within the filling and capping area, but instead with
the present invention a headspace modification unit 102 may receive
capped containers 1, and subsequently pressurise the container
immediately prior to sealing the container with a cap sealing
plug.
[0142] As an alternative, the headspace modification unit 102 could
also perform the usual function of a typical capping machine. The
unit could receive empty containers, apply caps containing the
plugs and subsequently torque the caps into position as well as
pressurise the container prior to ultimately sealing the container
through advancing the plug or some other sealing method.
[0143] Still further examples of alternative embodiments of the
present invention are illustrated in FIGS. 20 a-f. The cap 80 may
incorporate a rubber, or other suitable material, plug 182 within
the cap. This would provide the advantage of having an initially
leakproof seal to the container prior to pressurising the
headspace. In this way, the container could be charged with
pressure from a liquid or gas either prior to the cooling of the
contents, for example immediately after filling and capping by way
of overpressure, or the procedure could occur after the contents
have been cooled and there is a vacuum within the container. By way
of example, the cap and sealing plug 182 could be sterilized by
very heated water 66 after the liquid contents have cooled. This
would sterilize the upper surface of the cap and a heated liquid
could then be injected to compensate for vacuum pressure. Following
withdrawal of the injecting needle 102 the sterilizing heated
liquid could be removed as the container is ejected from the
pressure chamber. The rubber seal 182 would have closed off and
sealed the container to prevent any communication between the
headspace under the cap and outside air present as the chamber is
opened.
[0144] A further alternative for a suitable plug mechanism within a
cap 80 is illustrated in FIGS. 21 a-f. A ball-valve type closure
882 could be utilized to provide a hole through which headspace
modification may occur within the pressure chamber unit as
previously described. Once the headspace has been pressurized, a
rotating push rod 883 can close the ball valve while the headspace
is maintained under exact pressure as illustrated in FIGS. 21
d-f.
[0145] FIGS. 22a-c shows a typical example method of headspace
modification using the method of the present invention. An empty
container (not shown below the neck finish) is filled or even
`overfilled` to the brim of the neck finish, and a cap is applied
that has an opening through which headspace modification can be
achieved, for example a ball closure device. The capped neck
finish, at least, is contained within a pressure chamber (not
shown) and the container is placed under a calculated pressure.
This increase in pressure may be by injection of a gas as in the
illustrated example, or by overinjection of further liquid. During
this process the container will increase in size to a degree
allowing the fluid level to drop (if gas is being injected) and the
ball-valve closure may then be closed to maintain the increased
pressure within the container.
[0146] The same method procedure may occur using a more typical
`push-pull` type sport closure as illustrated in similar manner in
FIGS. 23 a-c.
[0147] As a further alternative to the present invention, and to
remove the need for a hole or plug mechanism within the cap itself,
and with reference to FIGS. 17a, a normal cap could be applied by a
capping unit but not forcibly torqued into position. The neck
finish can then be enclosed within the chamber 84 and the liquid or
gas forced into the container through the gap between the cap and
the thread mechanisms of the neck finish, as shown by passage of
liquid 86. Once the desired pressure is obtained the cap, as shown
in FIG. 17b, can then be torqued into position by advancing the
torque rod 85 within the chamber 84 while holding the container
headspace at pressure. In this embodiment the method may be
achieved using standard caps rather than modified caps. FIG. 17c
illustrates removal of the torque rod 85, correctly torqued cap 80,
immediately prior to ejecting the container head from the chamber
84.
[0148] It will be appreciated that the present invention offers
multiple choices in carrying out a headspace modification procedure
by way of modifying a typical capping machine. Such a piece of
machinery could easily be employed to also provide the function of
capping the container in addition to modifying the headspace during
the procedure.
[0149] FIG. 24 shows how a container could be contained within a
typical sealing chamber 84 from immediately below the neck support
ring 33 of the container.
[0150] FIG. 25 illustrates how the whole container could be
contained within a sealing chamber 84. In this embodiment the
container will not be stressed from the increased pressure until
after ejection from the sealing chamber.
[0151] FIG. 26 shows an alternative embodiment of the present
invention. It is envisaged that the sealing chamber 84 could
comprise optionally a lower end sealing skirt 884. In this example,
a sealing ring of soft material may be inflated under pressure of
water or gas through an inlet 883 to form a close contact with the
container shoulder. Gas or liquid may then be charged into the
pressure chamber headspace 87 through inlet 86 to modify the
container headspace prior to final sealing.
[0152] FIG. 27 shows how the sealing chamber of FIG. 26 could be
incorporated into a typical capping unit station with rotary head
applicators. This would allow for a modified capping unit to apply
a cap in the normal manner, but to modify the headspace prior to
application of torque to seal the cap on the container.
[0153] In facilitating the present invention, the complete or
substantial removal of vacuum pressure by displacing the headspace
prior to the liquid contraction now results in being able to remove
a substantial amount of weight from the sidewalls due to the
removal of mechanically distorting forces.
[0154] According to a further aspect of the present invention, and
referring to FIGS. 11a-c, following the introduction of a liquid,
which may be already heated or suitable for subsequent heating, a
cap may be applied including a small opening or aperture 81 which
is temporarily covered by a communicating seal 91. Thus a headspace
23d is contained under the main cap body 80 and above the fluid
level 40 in the container. The headspace 23d is not communicating
with the outside air at this stage and is therefore at typical
container pressure during the stages of cooling down on the filling
line.
[0155] As seen in FIGS. 12a-c, once the container has been
typically cooled to a level providing for labelling and
distribution the headspace 23e will be in an expanded state with a
lowered fluid level, and will have created a vacuum due to the
contraction of the heated liquid within the container.
[0156] As seen in this preferred embodiment of the present
invention, in order to remove the vacuum pressure a sealing chamber
84 is applied over the neck finish and cap combination to seal the
communicating seal 91 from the outside air (the upper, closed end
of the structure 84 is not shown).
[0157] Following the introduction of a sterilising medium 66, for
example by way of injecting heated water, preferably above 95
degrees C., or a mixture of heated water and steam, the sterilising
medium provides for the sterilisation of the internal surfaces of
the sealing chamber (84) and the communicating seal 91.
[0158] Now referring to FIGS. 13 a-c, while the sterilising medium,
is maintained within the sealing chamber 84, a plug mechanism 82 is
placed downwardly from a delivery device 83 towards the aperture
81. The plug mechanism pierces the communicating seal 91 and is
withdrawn again temporarily as shown in FIGS. 14a-c, providing for
communication between the sterilized volume within the sealing
chamber above the cap (80) and the headspace (23e) below the
cap.
[0159] As can be seen in FIGS. 14 a-c, the sterilising medium, for
example heated water at 95c, is immediately drawn into the
container through the open hole 81 due to the communicating seal
being pierced. This causes equalization of pressure or removal of
vacuum pressure within the container, such that the level of the
headspace 23f rises higher. In another preferred embodiment the
liquid would in fact be injected into the container under a small
pressure supplied from the sealing chamber 84 such that the
pressure within the container would in fact be a positive pressure
and the headspace would in fact be very small.
[0160] The integrity of the product volume within the container is
not compromised as the environment above the cap has been
sterilised prior to communicating with the headspace, and the
additional liquid supplied into the container replaces the volume
`lost` due to shrinkage of heated liquid within the container prior
to the method of headspace replacement described.
[0161] Following the pressure equalization, and now referring to
FIGS. 15 a-c, the delivery device 83 is advanced again such that
the plug 82 will be injected into the hole to close it off
permanently. At this point, the headspace 23f is under a controlled
pressure dependent on the volume of liquid having been delivered to
compensate for previous liquid contraction, as described above.
[0162] The sealing chamber may now provide for withdrawal of the
delivery device 83 which may now be done following a release of
sterilising medium and/or pressure within the chamber as the
container is ejected and returned to the filling line.
[0163] It will be appreciated that many variations of sealing
chamber may be utilised, for example the sealing chamber may only
seal directly to the top surface of the cap, rather than enclosing
the entire cap.
[0164] It will also be appreciated by those skilled in the art that
may forms of seal may be employed to provide the same the temporary
seal and also the plug mechanism to be utilised.
[0165] Thus a method of compensating vacuum pressure within a
container is described. Referring to FIGS. 16 a-c, the original
headspace level 40 experienced following cooling of heated contents
within a closed container provides for a vacuum to be present
within the first headspace 23d. Following compensation according
this embodiment of the present invention the headspace level
changes and perhaps rises 41 depending on the pressure contained
within the headspace and the pressure within the headspace 23f is
now preferably virtually at ambient pressure or preferably slightly
positive such that the sidewalls of the container are supported by
the slight internal pressure.
[0166] With reference to FIGS. 28a-d, an alternative embodiment of
the present invention also incorporates a compressible cap wherein
the compression occurs after filling and prior to the cooling of
the contents. In this way, by compression occurring when the liquid
is hot, the chamber 9 may be sterilized by the contents once it is
advanced into the container. The compressible cap may be contained
within a compression chamber as previously described, particularly
for large size containers. Containers of the 600 ml size for
example will require displacement to the order of 20-30 cc of
liquid, but containers of the 2000 ml range of size will require
displacement to the order of 70 cc of liquid. Such a large
displacement is difficult to achieve without having an extremely
large displaceable chamber entering the container. Therefore, in
order to keep the chamber size to a minimum, it is envisaged that
the compression chamber could provide an injection of a certain
amount of gas or liquid, and a compressible cap could provide the
rest of the compression required. In this way a minimum of gas is
also injected into the container. Of course, for small container
sizes it will be appreciated that just the compressible cap could
be utilised.
[0167] Unlike as described in prior art, the present invention
provides for the hot liquid within the container to sterilize the
underside of the internally presented surface of the inner chamber
9 as it has been compressed into the hot liquid contents.
[0168] Ordinarily, as the product cools, a vacuum will build up
within the container in the primary headspace 23b under the cap.
This vacuum may distort the container 1 to a degree if the walls
are not rigid enough to withstand the force.
[0169] However, as the internal pressure has been adjusted upwardly
prior to product cooling, the net effect may be a temporary raised
level of pressure during product cooling and substantially no
pressure once product cooling has finished, or perhaps even
advantageously a small amount of positive pressure.
[0170] Referring to FIGS. 29a-d, another similar embodiment of the
present invention provides for a mechanical cap that has a
mechanically controllable "out" and "in" position. The compressive
cap 8 is applied to the container 1 immediately post filling with a
hot beverage. In this particular embodiment the sealing surface 10
of the compressible inner chamber 9 is displaced higher than in the
previous example shown in FIGS. 24 a-d.
[0171] Referring to FIGS. 30a-b, a further embodiment of the
present invention is disclosed. The cap structure may be either a
2-piece construction, or a single unit whereby the compressible
inner chamber 9 engages with an internal thread on the neck finish
99 and causes compression of the headspace as the cap is applied
and secured to the container 1. Again, for larger size containers
this provides the ability to keep gas or liquid injection to a
minimum while utilising the displacement of the hot liquid contents
to provide the increase in container pressure as the container is
sealed.
[0172] Referring to FIGS. 31, a further embodiment of the present
invention is disclosed. The disclosed system generally includes an
empty container in-feed station prior to the filling station. This
may be through preblown containers being fed into the Filling
Enclosure, or may be through online blowmolding production as
illustrated. In the case of online blowmolding the preforms are fed
into an integrated blowmolder that also has its own housing that
may be continuously shielded alongside and joining the Filling and
Capping Enclosures.
[0173] The system may also contain a continuous container conveying
system, a container product fill station, a container head-space
dosing station, an optional liquified gas dispensing station, an
optional gas dispensing station, an optional liquid dispensing
station, a container sealing station, a container internal pressure
sensing station, a discharge conveyor and a reject apparatus.
[0174] Alternatively, as illustrated in FIG. 31 the conveying
system, fill station and container sealing station, or capping
station, may all be integrally contained within an enclosure or
integrated enclosures such that the inside environment may be
pressurised. This results in the headspace within each container
being pressurised to the desired level as the capper seals the
container. Effectively the ambient pressure within the enclosure is
artificially elevated while the container is sealed and the
internal pressure of the container rises immediately upon ejection
of the filled and capped containers as they are presented to a
lower ambient pressure outside of the system enclosures.
[0175] The system provides for the on-line control of the
head-space volume of each container as it is filled with product
through elevated ambient pressure around the container opening. The
head-space volume measurement is precisely controlled at the time
of sealing so that each container corresponds directly to its
individually measured head-space, and generally does not alter once
immediately sealed, except for variations caused by temperature
changes within the contained liquid and ambient temperature or
pressure changes.
[0176] With dosages being exactly correlated to the individually
measured requirements of each container, very uniform pressure
ranges are obtained as opposed to dosages based on expected fill
levels or after-the-fact average measurements. Therefore,
containers can be down gauged as they will not be required to
accommodate a wide pressure range. Furthermore, the system achieves
lower spoilage rates due to improperly pressurized containers
because the system immediately self adjusts for fill
variations.
[0177] A particular advantage of the present method and system is
the greater and more precise control allows for much lower pressure
dosing for hot fill containers. In prior methods a minimum pressure
value can only be assured by over pressurisation on average, such
that the lowest dose achieved will meet specifications. This has
resulted in generally high pressures achieved during the early
stages of hot fill, when the container is hot and malleable. As a
result the container is stressed significantly in most occasions,
necessitating the need for example for petaloid bases and container
designs more suitable to carbonated or pressure vessels. This
reduces significantly the design options available for containers,
and requires additional weight in the container surrounding the
base in order to achieve reasonable results.
[0178] With reference to FIGS. 32 a-c, an alternative embodiment of
the present invention also incorporates at least one portion of the
sidewall 801 configured to respond to vacuum pressure forces. In
this particular embodiment, the amount of gas or liquid required to
be forcibly injected into the container 1 within the sealing
chamber 84 prior to sealing the cap 800 onto the container is
reduced.
[0179] When a PET container is filled with liquid at a temperature
above 70 degrees Celsius the plastic walls become very soft and
elastic as the material passes its elastic modulus. With the
subsequent force being applied to the container by introduction of
a force to raise internal pressure, the sidewalls expand and the
overall volume of the container increases. Some of this increase in
volume is non-recoverable and results in the container becoming
larger than originally manufactured. A particular object of the
present invention is to reduce the amount of stress being applied
to the sidewalls to the lowest possible amount to prevent
unnecessary volume growth in the container.
[0180] This is of particular benefit when utilising very thin
sidewalls such as found in lightweight containers. It will be
appreciated therefore, that in a particular volume size container
to be filled with a heated liquid, for example in a range of 75 to
95 degrees Celsius, then the amount of gas or fluid required to be
introduced to compensate for the subsequent contraction of contents
may be reduced if the container has a residual capacity to account
for a portion of the expected contraction. For example, in a
container of 600 cc size, it may be expected that approximately
25-30 cc of fluid contraction may occur and therefore an amount of
gas or fluid equivalent to this would need to be injected into the
headspace during final sealing of the container in order to
compensate. By providing this compensation it may be possible to
therefore lightweight the container or change the shape of the
container as there is a much reduced need for the container to
resist vacuum pressure forces that would otherwise occur.
[0181] It will be appreciated that introduction of this additional
material creates extra stresses initially on the container. By
configuring at least a portion of the sidewall to respond to vacuum
forces, it is possible to reduce the amount of initial material
introduced, for example to 50% of the required amount, if the
sidewalls are able to provide compensation for 50% of the required
amount also.
[0182] It will be appreciated that a container-that is only
required to compensate for 50% of expected vacuum pressure through
sidewall compensation will be able to be made more lightweight than
a container required to compensate for the entire 100% through
sidewall compensation.
[0183] With reference to FIGS. 33 a-c an alternative embodiment of
the present invention also incorporates at least one transversely
oriented pressure panel 802 in the container 1. In this particular
embodiment the transverse panel is located in the base portion of
the container, but may equally be incorporated in the sidewall. In
this particular embodiment, the amount of gas or liquid required to
be forcibly injected into the container 1 within the sealing
chamber 84 prior to sealing the cap (800) onto the container is
also reduced. As explained above with reference to FIGS. 32 a-c,
the transverse panel may account for a portion of the required
vacuum compensation, for example 40%, when moved into the inverted
position as shown in FIG. 33c from the initial position as shown in
FIG. 33a. Inversion of the element 802 may be by way of mechanical
force for example. As the container can account easily for some of
the vacuum compensation required, there is only a need to provide
for approximately 60% of the required liquid contraction by way of
pressure injecting prior to sealing the cap. In this way there is
reduced stress applied to the container during processing.
[0184] With reference to FIGS. 34 a-c an alternative embodiment of
the present invention provides for both sidewall vacuum
compensation and transverse panel compensation to be combined with
headspace compensation for even less stress to be applied to the
container during processing. By way of example, it will be
appreciated that if the sidewall compensation elements 801 provide
approximately 30% of vacuum compensation, and the transverse panel
802 is able to provide approximately 40% of vacuum compensation,
then a charge of gas or liquid into the headspace during sealing
would only require approximately 30% of that required in a
container not having vacuum compensation elements equivalent to 801
and 802. It will be appreciated that varying amounts of
compensation may be attributed to each element.
[0185] With reference to FIGS. 35 a-c a further alternative
embodiment of the present invention is also provided. In the same
way as already described, at least one portion of the sidewall may
incorporate a vacuum compensation element 803. In this particular
embodiment, the element 803 is also configured to expand radially
outwardly under internal pressure as illustrated in FIG. 35c. It
will be appreciated that under internal pressure charge during
headspace sealing the vacuum compensation element 803 will reduce
the amount of stress within the container by expanding radially
outwardly first. If filled with a heated liquid, the contents will
subsequently cool inside the container and a pressure reduction
will occur. As this happens the element 803 will return to the as
moulded position shown in FIG. 35a and will then, subsequently be
able to provide further vacuum compensation. By way of example
only, if element 803 as shown in FIG. 35a is able to provide
approximately 30% of the required vacuum, then 70% of the
compensation would be required to be introduced during headspace
sealing. By incorporating a vacuum compensation element 803 that is
able to expand outwardly then the stress induced is reduced during
the initial phases by a significant amount.
[0186] With reference to FIGS. 36 a-c a further alternative
embodiment of the present invention is also provided. It will be
appreciated by the prior descriptions above that a container of the
present invention may be provided with sidewall vacuum compensation
elements or may be provided with sidewall vacuum compensation
elements that are able to expand radially outward under pressure to
reduce stresses during headspace modification and sealing
procedures. These containers may also be provided with transverse
pressure panel compensation elements also to further reduce the
amount of stress required to be imposed on the container during
processing. In this particular embodiment the transverse panel 802
is placed in the base of the container. It is envisaged by way of
example and with reference to FIGS. 35 a-c and FIGS. 36 a-c, that
element 803 may be able to provide approximately 30% of the
required vacuum compensation and base element 802 may provide
approximately 30% of the required vacuum compensation. Therefore,
40% of the compensation required would be injected into the
headspace during processing as previously described. As sidewall
element 803 is able to expand radially outward then the stress
imposed during processing and headspace modification is reduced
further.
[0187] With reference to FIGS. 37 a-c, even further stress
reduction is anticipated in a further embodiment of the present
invention. In a manner as described above, base element 804 is
configured to expand longitudinally outward to relieve the pressure
induced during headspace modification and injection of gas or
liquid during sealing. This reduces the stresses imposed upon the
container sidewall. In this particular embodiment, sidewall element
803 is also configured to expand radially outward under the
internal pressure. Therefore substantial ability is provided within
the container to reduce the stresses induced as gas or liquid is
injected into the container. Upon subsequent cooling of any heated
contents inside the container both sidewall element 803 and
transverse element 804 are able to be inverted inwardly to assist
vacuum pressure compensation.
[0188] Where in the foregoing description, reference has been made
to specific components or integers of the invention having known
equivalents then such equivalents are herein incorporated as if
individually set forth.
[0189] Although this invention has been described by way of example
and with reference to possible embodiments thereof, it is to be
understood that modifications or improvements may be made thereto
without departing from the scope or spirit of the invention.
* * * * *