Headspace modification method for removal of vacuum pressure and apparatus therefor
Inactive Publication Date: 2011-04-28
MELROSE DAVID MURRAY
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- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
[0024]In view of the above, it is an object of one possible embodiment of the present invention to provide a headspace sealing and modification method that can provide for removal of vacuum pressure such that there is substantially no remaining force within the container.
[0025]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.
[0026]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.
Problems solved by technology
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.
Even with such substantial displacement of vacuum panels, however, the container requires further strengthening to prevent distortion under the vacuum force.
The liquid shrinkage derived from liquid cooling, causes a build up of vacuum pressure.
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 ⅓ of the distance from an end to the container.
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.
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.
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.
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.
Headspace contains gases that in time can damage some products or place extra demands on container structural integrity.
Filling and sealing a rigid container at elevated temperatures can create significant vacuum forces when excessive headspace gas is also present.
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.
Method used
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[0055]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.
[0056]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.
[0057]Typically at a bottling plant the containers will be filled with a hot liquid and then capped before being subje...
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Abstract
To modify the headspace in a container to remove vacuum pressure, a container has a seal or cap which may provide a temporary opening into the container which is sealable under compression to provide a controlled raising of the internal pressure as the heated contents of the container cools. A sealing chamber (84) may enable the introduction of a fluid into the headspace (23b) to force the fluid level (40) lower. Other methods and apparatus are described.
Description
TECHNICAL FIELD OF THE INVENTION[0001]This invention relates generally to a method of light-weighting hot fill containers by modifying the headspace for the removal of vacuum pressure and apparatus therefor. This is achieved by filling a container with a heated fluid; which term for the purposes of this specification including both liquids and gases unless specified otherwise, sealing the contents of the container from contamination from outside air, and adjusting the pressure of the headspace during the capping process to negate vacuum forces generated within the container following fluid cooling. The headspace modification process displaces the fluid below the headspace in the upper neck region of the container downwardly prior to allowing the fluid contents to cool, and labelling the container. This invention further relates to hot-filled, and pasteurized products packaged in heat-set polyester containers and is particularly useful for packaging oxygen sensitive foods and beverag...
Claims
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Login to View More IPC IPC(8): B65B1/20B65D51/00
CPCB65B31/006B65B31/06B65D47/243B65B7/2842B65D79/005B67C2003/226B65B7/2807B65D47/30B65D79/0087
InventorMELROSE, DAVID MURRAY
OwnerMELROSE DAVID MURRAY