HK1145079B - Container structure for removal of vacuum pressure - Google Patents

Description

Container structure for removing negative pressure

The present application is a divisional application entitled "container structure for removing negative pressure" filed on 30/9/2003 by the applicant under application number 03824824.7.

Technical Field

The present invention relates generally to a container structure that allows for removal of negative pressure. This is achieved by turning a transverse suction plate arranged in the lower end wall, or bottom region, of the container.

Background

So-called "hot-fill" containers are well known in the art, and manufacturers supply PET containers to fill the containers with various liquids, which have relatively high temperatures, typically around 85 degrees celsius (185 degrees fahrenheit).

The container is made to withstand thermal shock of the hot liquid it holds, resulting in a "heat set" of the plastic container. The thermal shock is caused by the injection of hot liquid during filling or by heating the container after the liquid has been injected.

However, once the liquid in the sealed container cools, the volume of liquid in the container decreases, thereby creating a vacuum within the container. The contraction of the liquid causes a negative pressure on the sides or end walls of the container to pull inward. If the plastic bottle does not have a sufficiently rigid structure to resist such forces, this in turn can result in deformation of the plastic bottle wall.

Typically, the negative pressure is regulated by using a vacuum plate that deforms inwardly under the negative pressure. The prior art discloses a number of vertical vacuum panels that allow the container to withstand the intense heat of the hot-fill process. Such vertical vacuum panels are generally parallel to the longitudinal axis of the container and curve inwardly toward the longitudinal axis under negative pressure.

In addition to the vertical vacuum panels, many prior art containers also have flexible bottom regions to provide additional vacuum compensation. Many containers designed for hot-filling have variations in the end wall or bottom region to allow as much inward flexing as possible in order to regulate at least some of the negative pressure generated within the container.

However, all of these prior art techniques provide a horizontal or inwardly sloping or concave floor. These bottom surfaces have also been modified so as to be inwardly deflectable as much as possible. When the bottom region flexes due to pressure, it can move to a more inclined position than before the vacuum force is applied.

Unfortunately, however, the force generated under vacuum pulling longitudinally in the base region is only half of the force simultaneously generated in the transverse direction. Thus, a vertical vacuum plate can react more easily to forces than a plate arranged at the bottom. Furthermore, more surface area may be available around the perimeter of the container than in its end walls. Thus, sufficient vacuum compensation can be achieved by merely providing vertical vacuum panels over a large portion of the area of the peripheral wall of the container, typically 60% of the available area.

Even with such substantial movement of the vertical panels, however, the container needs to be further reinforced to prevent distortion under vacuum forces.

The liquid contraction due to the cooling of the liquid increases the negative pressure. The vacuum panel deflects toward this negative pressure until the vacuum force is reduced, better accommodating the smaller volume of the contents by effectively forming a smaller container. However, the smaller shape is held in place by the vacuum force generated. The more difficult the structure is to deflect inwardly, the greater the vacuum force generated. In the prior art, there is still a substantial vacuum within the container which tends to distort the overall shape unless a large, annular reinforcing ring is provided in a horizontal or transverse direction at least 1/3 from the end of the container.

In view of this, it is believed that it is not possible to provide complete vacuum compensation by merely varying the end wall or base region, as is known. The bottom region provides very little surface area in comparison to the side walls and reacts to half the ratio of force on the side walls.

It is therefore customary practice to only require partial assistance by the entire vacuum compensation produced by the base region. Furthermore, even if the bottom region is able to provide sufficient flexure to accommodate the shrinkage of all the liquid in the container, there may be an effective vacuum force and an effective stress on the bottom mounting ring. Forces may also be generated on the side walls, smooth side walls may be thicker in material distribution, may be reinforced by ribs or the like, or may be provided in a shape more compatible with mechanical deformation (e.g. square instead of circular) in order to prevent deformation.

For this reason, it is not possible to provide a container of the design of plastic containers without the vertical vacuum panels of the usual prior art on the side walls. Many manufacturers are therefore unable to commercialize plastic bottles of the same design as glass bottle designs with smooth sidewalls.

Us patent 6,595,380 (drivers) requests the provision of a total vacuum compensation by means of a bottom area, without the need for vertical vacuum panels on smooth sidewalls. This is proposed in combination with the known art and the practical application in the prior art. The Silver provides a slightly inward domed and concave bottom region to provide further inward movement under negative pressure. However, the percentage area required for the disclosed techniques and the described efficiencies is not considered by the present application to provide a viable solution to the problem.

In fact, the curvature in the bottom area is considered to be greatest in the horizontal bottom area, which is widely used, and it has been found that it does not provide sufficient vacuum compensation to avoid the simultaneous use of vertical vacuum panels.

Slivers do provide a reinforced bottom region by connecting the bottom region to the container securing ring to help prevent unwanted outward movement of the inwardly sloping or flat portions when the heated liquid increases the initial internal pressure within the newly filled and capped container. This connection is obtained by a rib structure, which also serves to reinforce the flat area. Although it may strengthen the region so that more vacuum force is applied to it, which in turn further reduces the curvature in the base region and thus the degree of curvature.

The applicant believes that the special "ribbed" approach suggested by Silvers can only provide about 35% of the required vacuum compensation, as the applicant does not believe that the improved end wall can effectively flex inwardly to fully account for liquid shrinkage that may develop. Therefore, the negative pressure is effectively kept to be desirably formed. Containers using this bottom structure still require a high degree of thickening of the side walls, and when the side walls are thickened during manufacture, the bottom area becomes thicker. The result is a less curved bottom region, which in turn reduces the efficiency of the vacuum compensation obtained.

The present invention relates to a hot-fill container which is an improvement of the hot-fill container described in international application WO02/18213(PCT application), the relevant parts of the entire specification of which are incorporated herein.

The PCT application, which addresses the background of the design of hot-fill containers and the problems resulting from these designs, discloses overcoming, or at least making improvements to, the problems of the original design by design.

In the PCT application, a semi-rigid container is provided having a generally vertically corrugated vacuum panel portion. Such transversely disposed vacuum panel portions include an initiating portion and a controlling portion which are generally resistant to expansion caused by the collapsed condition.

Further description of the PCT application is the covering of vacuum panels at various locations along the vessel wall.

When such a panel is provided in the end wall or base region, there is a problem in that the stability of the panel is compromised if it cannot be moved longitudinally far enough into the container to no longer form part of the container in contact with the upright surface of the container.

Another problem that exists when using a transverse panel in the bottom end wall is the potential energy caused by the impact deflection of the roll-over panel as a full and capped container is dropped. This may be formed in a side-drop flexible or non-structural wall container. The impact deflection of the side walls causes a shock wave of internal pressure acting on the plate. In such cases, improved panel structures are desired to further prevent unfolding of the panel, or preferably to prevent this reverse movement with initial area structures.

Disclosure of Invention

In light of the above, it is an object of a preferred embodiment of the present invention to provide a plastic container structure having a transverse pressure panel in its lower portion that is configured to remove negative pressure so that there is substantially no residual force within the container.

It is a further object of a preferred embodiment of the present invention to provide a container having a transverse pressure panel that attenuates the effects of adjacent walls to allow for greater inward and longitudinal movement.

It is a further object of a preferred embodiment of the present invention to provide a container with a transverse pressure panel that is inwardly disposed to a position above a securement loop of the container final structure, thereby creating a new bottom region with a greater securement loop or footprint area that is protected from top loading forces applied to the container during commercial distribution.

It is a further object of a preferred embodiment of the present invention to provide an improved transverse pressure plate having an initial portion that uses substantially the same angle as the control portion, thereby removing a greater amount of negative pressure and also better resisting outward deflection.

Further and alternative ones of all separately understandable objects of all embodiments of the invention are at least offered to the public for their selection.

According to one aspect of the present invention there is provided a container having a longitudinal axis, an upper portion having an opening into the container, a body portion extending from the upper portion to a base closing one end of said container, the container having an at least substantially transverse pressure panel portion disposed in the base, the pressure panel portion being capable of being collapsed from a longitudinally inclined position to an inverted position to compensate for pressure variations occurring in the container, the pressure panel portion including an initiator portion and a control portion, the initiator portion being less resistant to collapsing pressure to collapse prior to the control portion.

According to a further aspect of the invention, a container as described in the preceding paragraph has at least one substantially transverse vacuum panel portion provided at the base, the vacuum panel portion being adapted to collapse from a longitudinally inclined position to an inverted position in use so as to compensate for pressure variations within the container caused by cooling of the liquid therein after closure of the container, whereby less force is exerted on the inner wall of the container.

According to a further aspect of the invention, a container as described in the preceding paragraph has a single substantially transverse vacuum panel portion disposed within the base and connected to the side wall by a breakaway or hinged structure, the vacuum panel portion being adapted to buckle from a longitudinally inclined position to an inverted position in use to compensate for pressure variations occurring within the container.

Preferably in one embodiment the disengagement structure connects the pressure plate portion and the body portion and is an area that allows the pressure plate to move longitudinally farther inwardly and upwardly.

Preferably in one embodiment the vacuum panel portion is free of stiffening ribs that inhibit substantial longitudinal movement and turnover.

Preferably in one embodiment the vacuum panel may include a groove configuration or the like to allow for an even circumferential distribution of the creasing force to provide for increased control of the panel portion in creasing from one inclined position to another to help prevent the vacuum panel from undesirably returning to an original position.

Preferably in one embodiment, after creasing, the upstanding support for the container is provided by a lower portion of the container side wall which provides an alternative upstanding support for the container.

According to a further aspect of the present invention there is provided a method of compensating for pressure variations within a container defined in any one of the preceding seven paragraphs, wherein the method comprises applying a force to each vacuum panel portion to cause the corrugations to occur.

According to a further aspect of the present invention there is provided a hot-fill container substantially as hereinbefore described with reference to any one of the embodiments shown in the accompanying drawings.

Other aspects of the invention that relate to novelty considerations will become apparent from the description below.

Drawings

FIG. 1 shows a cross-sectional view of a hot-fill container before collapse, according to one possible embodiment of the present invention;

FIG. 2 shows the container of FIG. 1 in a collapsed condition;

FIG. 3 shows the lower portion of FIG. 1 prior to deflation;

FIG. 4 shows the lower portion of FIG. 2 after collapse;

FIG. 5 shows a bottom view of the container of FIG. 1 prior to collapse of the lower portion thereof;

FIG. 6 shows the lower portion of FIG. 1 prior to deflation;

FIG. 7 shows the lower portion of FIG. 2 after collapse;

FIG. 8a shows a cross-sectional view of a hot-fill container according to another embodiment of the present invention prior to collapse;

FIG. 8b shows a cross-sectional view of the container taken along line C-C in FIGS. 8a and 9;

FIG. 9 shows a bottom view of the container of FIGS. 8a, 8b and 10 prior to collapse of the lower portion thereof;

FIG. 10 shows a cross-sectional view of the container taken along line D-D of FIG. 9;

FIGS. 11a-d show cross-sectional views of a container incorporating a push rod to provide plate corrugations in accordance with another embodiment of the present invention;

FIGS. 12a-d show cross-sectional views of a container incorporating a push rod to provide plate corrugations in accordance with yet another embodiment of the present invention;

FIG. 13 shows a lower portion of another embodiment of the present invention prior to collapse;

FIG. 14 shows the lower portion of FIG. 13 during an initial stage of deflation;

FIGS. 15a-b show side and cross-sectional views of the container of FIG. 9 containing outwardly projecting grooves;

FIG. 15c shows a bottom view of the lower portion of the container of FIGS. 15a and 15b with dotted outlines along lines E-E and F-F;

FIG. 15d shows a perspective view of the lower portion of the container of FIGS. 15 a-c;

FIG. 16a shows a side view along line I-I of the container of FIG. 16c containing inwardly projecting grooves according to another embodiment of the present invention;

FIG. 16b shows a cross-sectional view of the lower portion of the container of FIG. 16c taken along line J-J;

FIG. 16c shows a bottom view of the lower portion of the container of FIGS. 16a and 16b with dotted outlines along lines G-G and H-H;

FIG. 16d shows a perspective view of the lower portion of the container of FIGS. 16 a-c;

FIGS. 17a-d show a side view, a side perspective view, an end perspective view and an end view, respectively, of the container of FIG. 15;

FIGS. 18a-d show a side view, a side perspective view, an end perspective view and an end view, respectively, of the container of FIG. 16;

Detailed Description

The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

As mentioned above, in order to accommodate the vacuum forces during cooling of the contents of a thermoset container, the container is typically provided with a series of vacuum panels around its side walls and an optimized lower portion. Under the influence of the vacuum force, the vacuum plate is deformed inwardly, while the lower part is deformed upwardly. This prevents undesired twisting of other parts of the container. However, the container is still subject to internal vacuum forces. The plate and the lower part merely provide a suitable structure to resist this force. The more resistant the structure, the more vacuum force is present. In addition, the presence of the vacuum panels can be felt by the end user when gripping the container.

In a filling plant, containers are typically filled with a hot liquid prior to being subjected to a cold water spray, and subsequently capped, resulting in a vacuum being formed within the container, which the container structure needs to be able to overcome. The present invention relates to hot-fill containers and a structure for substantially removing or substantially eliminating negative pressure. This structure allows greater design freedom and lighter possibilities, since it no longer requires structures that resist vacuum forces that might mechanically deform the container.

As mentioned above and in the PCT application, various proposals have been made for hot-fill container designs.

Another improvement in the PCT application relating to hot-fill containers is the provision of outwardly inclined and transversely disposed vacuum panels between the lower portions of the side walls and the inwardly domed lower regions. In this position, the container has poor stability and, in the case of a smaller diameter in the lower region, no good support of the securing ring is possible. In addition, a disengagement structure is preferably provided that provides a hinged connection to the vacuum panel at the junction with the lower portion of the sidewall. The disengagement structure provides the vacuum panel with a greater range of longitudinal movement than would be possible if the vacuum panel were connected to the side wall, for example by ribs. One side of the breakaway structure remains adjacent the sidewall, allowing the other side of the breakaway structure adjacent its initial portion to flex inwardly and upwardly. Thus, the disengagement structure allows for a greater deflection of the initial portion and allows the panel portion to move longitudinally further away from the previously outwardly inclined position while allowing the panel portion to buckle inwardly relative to the container and upwardly relative to the initial lower position. The lower portion of the sidewall is thus subjected to a lower force during such inversion. During this action, the lower part moves longitudinally upwards and into the container.

In addition, the breakaway structure allows the vacuum panels to simultaneously form part of the lower portion of the container when the vacuum panels are partially creased inwardly and upwardly. This improvement has at least two significant advantages.

First, since the vacuum plate is provided to form the lower portion after the corrugation, a mechanical force can be immediately applied to the vacuum plate so as to apply a steering force. This allows more control over the above operation, which may be exerted, for example, by a mechanical pusher engaging the lower portion of the container to reset the shape of the container. This allows for more design optimization for the initial portion.

Second, as the transverse vacuum panel is pushed from an outward position to an inward position, the vacuum panel is virtually completely removed from the view. This means that no significant design features are added to the major portion of the container sidewall to create vacuum compensation. Thus, a substantial portion of the side walls of the present invention may be free of structural components, as desired, and the containers of the present invention are capable of replicating the walls of clear glass containers, as desired. Alternatively, since little or no vacuum may remain in the container after the vacuum panels are inverted, any design or shape can be immediately applied without concern for fully resisting the vacuum forces created in other hot-filled packages.

This design allows for a wider retaining ring. The breakaway structure allows the vacuum panel to move longitudinally so that there is no contact between any portion or upwardly domed lower portion of the vacuum panel and the associated lower surface. A retaining ring is then positioned adjacent the lower portion of the sidewall of the breakaway structure.

Furthermore, by adding more control over the movements and forces of the present invention, it is possible to allow the initiation portion to have the same acute angle as the control portion. This allows for increased volume transfer during inversion and improved resistance to return to the original position.

Referring to the drawings, figure 1 shows, by way of example only, a bottle-shaped container in diagrammatic cross-section. The container is generally indicated by arrow 10 and has a neck 12 and a sidewall 9 extending to a lower portion 11 or bottom of the sidewall 9, and an underlying bottom 2.

The container 10 is typically blow molded from any suitable plastic material, typically polyethylene terephthalate (PET).

The base 2 is shown provided with a plurality of stiffening ribs 3 to form a "champagne-type" lower portion, although this is only an example.

In fig. 1, the lower portion 11 of the sidewall, which is the pressure panel, is shown in an unfolded state, and a ring or annular portion 6 is then arranged above the lower level of the bottom 2, which forms the securing ring or support 4 of the container 10.

In fig. 2, the lower part 11 of the side wall is shown as having been folded inwards, so that the ring or annular part 6 is arranged below the lower level of the bottom 2 and forms a new fixing ring or support for the container 10.

To facilitate its formation, as can be seen in particular in figures 3 and 4, adjacent to the ring or annular portion 6 is an arch or recess 8 and a disengaging structure 13, here a substantially flat area without ribs, able to bring the bottom 2, after creasing, to lie effectively entirely on the line a-a, not visible in the lower part of the container. However, many other configurations for the disengaging structure 13 are also conceivable.

Referring now in particular to fig. 5, the base 2 with the reinforcing ribs 3 is shown surrounded by the annular portion 6 of the side wall 9 and the disengagement arrangement 13, which is annular in fig. 5. In this particular embodiment, a lower portion 11 is shown having an initial portion 1, the initial portion 1 forming part of a collapse or inversion zone, thereby creating a longitudinal collapse force prior to the remainder of the collapse or fold zone. The base 2 is shown arranged in a lower retaining ring 4, which retaining ring 4 will be the first support position for the container 10 before the fold plate is inverted.

Connected to the initiator portion 1 is a control portion 5, in this embodiment the control portion 5 is a more steeply angled flip portion which resists further expansion in the deflated condition.

The outer circumference of the lower portion 11 forming the side wall 9 is shown, the ring or annular portion 6 providing new container support after collapse of the lower portion 11.

To increase the evacuation of the vacuum, it will be appreciated that it is preferred to provide the control portion 5 of the lower portion 11 with an acute angle, wherein the lower portion may act as a pressure plate. As shown in fig. 6, the control portion 5 of the pressure plate is typically designed with an angle varying between 30 and 50 degrees. It is preferable to ensure that the angle is designed at least more than 10 degrees. The initiation portion 1 in this embodiment may have a small angle of at least 10 degrees less than the control portion.

By way of example, it will be appreciated that when a pressure plate is inverted by mechanical pressure, it may undergo a double angular change applied to it. If the conical control 5 is designed to be 10 degrees it will provide a plate variation equivalent to 20 degrees. It has been found that the vacuum compensation provided in the hot-fill container at such low angles is insufficient. Thus, it is preferable to provide a more acute angle.

Referring to fig. 6 and 7, it is appreciated that the control portion 5 may be initially designed to be inclined outwardly approximately 35 degrees and then flipped over and changed in angle by approximately 70 degrees. The initial portion may be 20 degrees in this example.

Referring to figures 8a and 8b, where like parts have been given like numbers as previously described, it is envisaged that in a possible embodiment of the invention the initial portion may be rearranged and the control portion 18 may then substantially provide a continuous tapered region around the periphery of the base portion 2.

The initial portion 1 and the control portion 5 in the embodiment described in the preceding figures are here arranged at a general (common) angle, so that they form a uniformly inclined plate portion. However, the initiator 1 may still be shaped to provide a minimum area to resist inversion, so that it still provides an initial region of collapse or inversion even though it is at the same angle as the control section 18. In this embodiment the initiation portion 1 causes the pressure plate to invert from its widest diameter adjacent the release formation 13.

In this embodiment, the container side wall 9 is of a "glass type" construction, i.e. without additional stiffening ribs or plates which may be formed in a typical container, particularly if resistance to forces generated by negative pressure is required. But additionally structure may be added to the taper of the pressure plate used as the vacuum plate to further increase control over the inversion process. For example, the tapered portion of the vacuum plate may be divided into a plurality of recessed regions. Referring particularly to fig. 8a and 9, the plate portions projecting outwardly and evenly distributed about the central axis forming the area of the larger corner assembly 19 and the area of the smaller corner assembly 18 may provide greater control over the inversion of the plate. This geometry provides greater resistance to the flipping of the panel and more evenly distributed force when in the flipped position.

Referring to fig. 15a-c and 17a-d, a groove that is convex or protrudes downwardly and outwardly is shown.

In addition to outwardly formed grooves, concave or inwardly formed grooves are also envisioned. The inward groove provides less resistance to the initial flipping force but is accompanied by greater resistance to flipping back to the initial position. In this way they behave in much the same way as the ribs to prevent the panel from being forced back to the outwardly inclined position but to allow the hinge to move from the first outwardly inclined position to the inwardly inclined position. Such inwardly or outwardly directed grooves or protrusions act as ribs to increase the force required to flip the panel. It will be appreciated that the mechanical action applied to flip the panels will be sufficient to overcome any rib reinforcing panels and when removed from the rib reinforcing panels, for example a strong groove, will be severely resistant to returning to its original position if the container is dropped or impacted.

Referring to fig. 16a-d and 18a-d, which show concave or upwardly and inwardly projecting grooves, the contours G and H of fig. 16c depict the concavity by two cross-sections (relief).

Other embodiments including the use of a groove and projection arrangement are also within the scope of the invention.

In the embodiment shown in fig. 11a-d, the container is blow molded with pressure panel 20 in an inwardly and upwardly inclined position. Before using the vacuum vessel as shown in fig. 11d, a force can be applied to the pressure plate 20, for example by means of a mechanical push rod 21 which enters the neck region and pushes downwards, so as to place the plate in an outwardly inclined position.

In the embodiment shown in fig. 12a-d, after the vacuum in the filled bottle is created as a result of the filling, capping and cooling water spraying of the bottle, the creation of some relative movement of the bottle bottom, such as by mechanical push rod 21 or relative thrust or otherwise, may exert a force on pressure plate 20 to force pressure plate 20 from an outwardly inclined position to an inwardly inclined position. Because the internal volume is forcibly reduced, any distortion caused by distortion of the bottle shape prior to inversion of the pressure plate 20 is eliminated. When the pressure panel 20 is inverted to cause the pressure to rise, the vacuum within the container is removed. This pressure increase reduces the negative pressure until atmospheric pressure is reached or just right before a positive pressure is obtained.

In another embodiment of the invention it will be appreciated that the plate is inverted in the manner shown in figures 12a-d to provide a means of accommodating internal forces such as those present during heat sterilization or similar sterilization. In this way, the plate will provide a reduction in the internal pressure generated and will be able to adjust the vacuum force generated when the product cools down.

In this manner, the panel will flip from the upwardly inclined position of fig. 11a to 11b to the downwardly inclined position shown in fig. 12a-d unless this mechanical action is not provided. Instead, the force is replaced by the internal pressure of the contents.

Referring again to fig. 12a-d, it can be seen that the major portion of the side wall 9 may be free of any structural components due to the provision of a crease in the lower portion of the side wall 9 of the container 10, so that the container 10 can substantially replicate a glass container, if desired.

Although a particular structure for the lower portion of the side wall 9 has been shown in the drawings, it will be appreciated that other structures may be provided. For example, in another embodiment, a plurality of folds can be incorporated around the base 2.

Many different decoupling or hinge structures 13 may be provided without departing from the scope of the invention. Referring particularly to fig. 6 and 7, it can be seen that the side of the disengagement feature 13 provided to the pressure panel can be an enlarged area to provide an increased longitudinal movement upward into the container after inversion.

In another embodiment of the present invention, and with reference to fig. 13 and 14, it can be seen that the widest portion 30 of the pressure plate can be folded over prior to the narrower portion 31. The initiator may be constructed to allow for the use of thinner material, etc., to cause the plate to begin to invert in front of its narrower portion, at a location of greater diameter. In this case, the widest part 30 of the plate, which is disposed radially further from the central axis of the container, is folded back in front of the narrow part 31 as an initial part.

In the foregoing specification, reference numerals have been used to designate specific parts of the invention or the invention as a whole, and such identical parts have been incorporated herein as if individually set forth.

Although the invention has been described by way of example in connection with possible embodiments, it is to be understood that modifications and variations are possible in light thereof without departing from the scope of the invention as defined in the appended claims.

Claims (51)

1. A plastic container having a longitudinal axis; an upper portion having an opening into the container; a body portion extending from the upper portion to the lower portion; said lower portion including a bottom, said bottom closing one end of said container; said container having at least one transverse pressure panel portion disposed within said lower portion, said pressure panel portion being capable of collapsing from an inclined position to an inverted position to change the internal volume within the container, said pressure panel portion including an inclined portion that is inclined at an angle greater than 10 ° in the inclined position relative to a plane orthogonal to said longitudinal axis, wherein said pressure panel portion is connected to the lower portion of said container by a breakaway or hinge structure.

2. The container of claim 1, wherein the inclined portion is inclined at an angle between 30 ° and 45 °.

3. A container according to claim 1, wherein said pressure panel portion comprises an initiator portion and a control portion, said initiator portion being less resistant to the buckling pressure and providing buckling of said control portion.

4. A container as claimed in claim 3, wherein the initiator causes the control portion to invert and bend inwardly into the container or outwardly away from the container.

5. A container as claimed in claim 3, wherein said initiator is disposed adjacent a widest edge of said pressure panel portion.

6. A container as claimed in claim 3, wherein the inclined portion is a control portion.

7. A container as claimed in claim 3, wherein the initial portion is inclined at the same angle as the angle of inclination of the control portion.

8. A container according to claim 3, wherein the initiation portion is inclined at an angle which is less than the angle of inclination of the control portion.

9. The container of claim 8, wherein the initiation portion is inclined at an angle of at least 10 ° less than the plane normal to the longitudinal axis.

10. The container of claim 9, wherein the control portion is inclined at an angle of 35 ° and the initiation portion is inclined at an angle of 20 °.

11. A container as claimed in any one of the preceding claims wherein said pressure panel portion is capable of collapsing from said tilted position to said inverted position to compensate for pressure variations occurring within the container.

12. A container as claimed in claim 11, wherein in use said pressure panel portion provides compensation for reduced pressure induced within said container such that less force acts on the walls of said container.

13. The container of claim 12, wherein said reduced pressure results from cooling of the heated liquid within the container after said container is capped.

14. The container of claim 12, wherein the compensation is such that there is no pressure reduction within the container.

15. A container as claimed in claim 11 wherein said pressure panel portion is capable of collapsing from an inverted position to an inclined position to compensate for pressure build-up within said container.

16. A container as claimed in claim 15, wherein said pressure panel portion is adapted to provide, in use, compensation for increased pressure induced within said container upon heating of liquid within the container after said container has been capped.

17. A container as claimed in claim 1 or claim 3 wherein said pressure panel portion is adapted to resist expansion from an inverted position.

18. A container as claimed in claim 1 or claim 3 wherein said pressure panel portion is adapted to be longitudinally inverted in use under externally applied mechanical force.

19. The container of claim 18, wherein a portion of the base is configured to engage a mechanical push rod.

20. A container according to claim 1 or 3, wherein the pressure panel portion has a variable width and is turned from its widest part to its narrowest part.

21. A container as claimed in claim 1 or claim 3 wherein said pressure panel portion is adapted to retract said base further longitudinally into said body portion.

22. A container as claimed in claim 21 wherein said pressure panel portion is adapted to displace a lowermost portion of said base into a configuration providing fixed support for said container.

23. A container as claimed in claim 1 or claim 3, wherein the structure of the container is such that, in use, a top load force applied to the container is transmitted from the base to a portion of the side wall of the container.

24. A container as claimed in claim 1 or 3, wherein said pressure panel portion includes an outwardly projecting portion.

25. A container as claimed in claim 1 or 3, wherein said pressure panel portion includes an inwardly projecting portion.

26. The container of claim 1 or 3, wherein the bottom further comprises a centrally located upwardly projecting portion connected adjacent an inner boundary of the pressure panel portion and closing a bottom of the container.

27. The container of claim 26, wherein the upwardly projecting portion is adapted to move upwardly when the pressure panel portion is inverted.

28. A container as claimed in claim 1 or claim 3 wherein said pressure panel portion is located within said base.

29. A container as claimed in claim 1 or claim 3 wherein said pressure panel portion includes a plurality of grooves forming tapered regions in said base.

30. The container of claim 29, wherein the recess is outwardly convex.

31. The container of claim 29, wherein the recess is concave.

32. A container as claimed in claim 1 or claim 3, wherein said container further includes a securing ring surrounding said pressure panel portion, said securing ring providing stability to the container when the pressure panel portion is in the inverted position.

33. The container of claim 32, further comprising a trough-shaped arch abutting an inner boundary of the securing ring, the arch surrounding the pressure plate portion and being displaced within the container more than an upper boundary of the pressure plate portion.

34. The container of claim 33, wherein said disengagement or hinge structure connects an adjacent widest boundary of said pressure panel portion to said arch, said disengagement structure providing greater inward upward longitudinal movement of said pressure panel portion.

35. The container of claim 1, wherein the breakaway structure is relatively flat compared to the longitudinal axis.

36. The container of claim 1, wherein the disengagement feature is relatively ribless and separates a widest point of the pressure panel portion from the trough-shaped arch portion.

37. A container as claimed in claim 1 or 3, wherein said pressure panel portion is free of stiffening ribs which inhibit longitudinal movement and inversion.

38. A container as claimed in claim 1 or claim 3 wherein said inclined portion of said pressure panel portion is inclined outwardly in said inclined position and inwardly in said inverted position.

39. A container as claimed in claim 1 or 3 wherein said inclined portion of said pressure panel portion is inclined inwardly in said inclined position and outwardly in said inverted position.

40. A plastic container having a bottom, the plastic container adapted for vacuum absorption, the container comprising: an upper portion having a mouth defining an opening into the container; a neck extending from said upper portion; a body portion extending from said neck portion to a base, said base closing an end of said container; the upper portion, the neck portion, the body portion and the base cooperating to define a receiving chamber within the container, wherein a product can be filled into the receiving chamber, the container comprising a securing ring defining a support surface, said container being supported on said support surface, said base further comprising a central portion and a pressure panel portion surrounding said central portion, said pressure panel portion defining an inwardly inclined forming portion when said container is filled and sealed, said inwardly inclined contoured portion being defined by a surface inclined toward the longitudinal axis of said container at an angle of greater than 10 ° relative to said support surface, the central portion and the pressure plate portion are movable to accommodate vacuum forces generated within the container, wherein said pressure panel portion is connected to the lower portion of said container by a breakaway or hinge structure.

41. The container of claim 40, wherein the central portion is configured to engage a mechanical push rod.

42. A container according to claim 40 or 41, wherein the central portion is at least partially defined by a push rod located on a longitudinal axis of the container.

43. A plastic container, comprising: a closed bottom connected to a flat rigid fixation ring, said bottom comprising a central annular flexible portion curved from a convex configuration to a concave configuration with respect to a support surface; a body portion extending above the sole, the body portion including a wall portion and a neck portion extending above the body portion, the neck portion including a dispensing opening; wherein the transition between the retaining ring and the central annular flexible portion allows flexing, the central annular flexible portion being configured to collapse upwardly around the retaining ring in response to a vacuum created within the container and the wall portion remaining unchanged, wherein the central annular flexible portion is connected to the lower portion of the container by a breakaway or hinge structure.

44. A method of raising pressure within a plastic container, the method comprising:

filling a plastic container with a liquid, the plastic container having a longitudinal axis; an upper portion having an opening into the container; a body portion extending from said upper portion to a lower portion, said lower portion including a bottom, said bottom closing one end of said container; said container having at least one transverse pressure panel portion disposed within said lower portion, said pressure panel portion including a portion that is outwardly inclined at an angle greater than 10 ° relative to a plane orthogonal to said longitudinal axis, wherein said pressure panel portion is connected to said lower portion of said container by a breakaway or hinge structure;

capping the container; and

applying a force to the container such that the pressure panel portion buckles from an inclined position to an inverted position to cause a rise in pressure within the container.

45. The method of claim 44, wherein the force applied to the container is an externally applied mechanical force.

46. The method of claim 45, wherein the force is applied by a mechanical push rod engaging a portion of the base.

47. The method according to claim 44 or 45, wherein said pressure panel portion comprises an initiator portion and a control portion, said initiator portion being less resistant to the creasing pressure and providing the creasing prior to said control portion, said force applied to said container resulting from pressure variations within said container.

48. A method according to claim 44 or 45, wherein the pressure rise compensates for a pressure decrease in the vessel.

49. The method of claim 48, wherein said container is filled with a heated liquid, said liquid being cooled after said container is capped.

50. The method of claim 48, wherein the pressure rise causes the resulting pressure within the vessel to be atmospheric pressure.

51. The method of claim 48, wherein the pressure rise causes a resultant pressure within the vessel to be greater than atmospheric pressure.