CN1345280A - Containers with pressure sensitive panels - Google Patents

Abstract

A container (1), suitable for use as a hot-fill container, comprises a controlled-flexing bendable plate (3) which can be reversed and bent under pressure, such as hot-filling conditions, to avoid deformation and permanent deformation of the container (1). The bendable plate (3) comprises an actuating portion (8) which is less convex than the rest of the bendable plate and which initiates the deflection of the bendable plate (3).

Description

Containers with pressure sensitive panels

technical field

This invention relates to an adjustable pressure container, and more particularly to a polyester container capable of filling hot liquids, and an improved side wall construction for such a container.

Background technique

"Hot fill" applications place high and complex mechanical stresses on the container structure due to thermal stresses during filling and immediately after capping, liquid pressure and vacuum pressure when the liquid cools.

Due to the introduction of hot liquid, thermal stresses are applied to the walls of the container. The hot liquid causes the container walls to soften and shrink unevenly, causing distortion of the container. Therefore, polyester must be heat-treated in order to change the molecular structure so that the container exhibits thermal stability.

During the filling process and long thereafter, pressure and stress act on the side walls of heat-resistant containers. When a container is filled with hot liquid and sealed, the initial liquid pressure and increased internal pressure act on the container. Thermal shrinkage causes the container to be partially evacuated as the liquid and the air headspace beneath the lid subsequently cool. The vacuum created by cooling tends to mechanically deform the vessel walls.

In general, containers that incorporate multiple longitudinal planes are more likely to withstand vacuum forces. U.S. Patent 4,497,855 to Agrawal et al. discloses a container having a plurality of recessed collapse panels separated by land areas, which allow uniform inward deformation under vacuum force. The vacuum effect is controlled without affecting the appearance of the container. The plates are drawn inwardly to remove the internal vacuum and thereby prevent excessive forces from being applied to the container structure which would otherwise deform the structure of the rigid struts or bonded areas. However, the amount of "bend" obtainable in each panel is limited, and as the limit is approached, the forces transmitted to the side walls increase.

In order to minimize the effect of the forces transmitted to the side walls, many prior art efforts have been made to provide hardened areas on the container, including the plate, to prevent the container structure from yielding to the vacuum forces.

The provision of horizontal or vertical annular sections or "ribs" throughout containers is common practice in container construction and is not limited to hot fill containers. Such an annular portion will reinforce the area in which it is deployed. U.S. Patent No. 4,372,455 to Cochran discloses a longitudinal reinforcing annular rib placed in the region between flat surfaces subjected to inwardly deformed hydrostatic pressure under vacuum force. U.S. Patent No. 4,805,788 to Aklho Ota et al. discloses a longitudinally extending rib on the side of the plate to strengthen the container. Akiho Ota also discloses the reinforcing effect of providing a larger step in the side of the bonded area. This provides greater size and strength to the rib area between the plates. U.S. Patent No. 5,178,290 to Akiho Ota et al. discloses grooves that reinforce the plate area itself.

U.S. Patent No. 5,238,129 to Akiho Ota et al. further discloses annular ribs that reinforce the hot fill plate portion of the bottle in a horizontal orientation in a strip fashion at the upper, lower, and outer portions.

In addition to the need to strengthen the container against thermal and vacuum stress, consideration also needs to be given to the initial liquid pressure, and the increased internal pressure acting on the container when hot liquid is introduced and subsequently capped. This results in stresses on the side walls of the container. This forces the hot plate outward, causing the container to bulge.

Thus, U.S. Patent No. 4,877,141 to Hayashi et al. discloses a plate structure that can withstand an initial and inherent outward bow caused by internal liquid pressure and temperature, and subsequent bowing due to the vacuum created during cooling. Curved inside. It is important that the shape of the plate remains relatively flat, but that the central portion is shifted slightly in order to strengthen the plate, but not prevent it from moving radially inwards and outwards. However, since the plate is generally flat, the amount of movement is limited in both directions. Naturally, for a particularly good elasticity, there are no plate ribs, which would prevent the outward and inward return movement of the plate as a whole.

US Patent No. 5,908,128 to Krishnakumar et al. discloses another flexible sheet for reacting to liquid pressure and temperature forces generated after filling. Relatively standard "hot fill" container geometries are disclosed for "pasteurizable" containers. It is stated that the pasteurization process does not require the container to be heat set prior to filling, as the liquid is introduced in a cooler state and heated after capping. Concave plates are used to compensate for pressure differences. However, in order to be flexible during both radially inward and subsequent radially outward movements, the plate maintains a shallow inward bow to withstand the internal pressures and temperatures of the bar process response to change. The temperature increase, sustained for a period of time after capping, softens the plastic material and thus allows the inwardly bowed panels to bend more easily under the resulting forces. However, it was revealed that too much bending would prevent this. Both the provision of a shallow bow and the softening of the material under the action of heat avoid permanent deformation when forced into the opposite bow. Thus, just as in a standard hot-fill bottle, the amount of force transmitted to the container wall is again determined by the amount by which the plate can bend. However, the amount of bending is limited due to the need to maintain a shallow concavity in the radial shape of the plate. Thus, the bottle can be reinforced in a number of standard ways.

US Patent 5,303,834 to Krishnakumar et al. further discloses "bendable" panels that are displaceable from a convex position to a concave position to provide a "squeezable" container. Vacuum pressure alone cannot invert the plates, but they can be manually forced to invert. Since a great deal of force is required to hold the plate in the inverted position, and this must be maintained manually, releasing the squeezing force will cause the plate to automatically "spring" back to its original shape. By employing multiple longitudinal bending points, permanent deformation of the plate due to the presence of the initial bulge is avoided.

U.S. Patent 5,971,184 to Krishnakumar et al. further discloses "bendable" panels that can be moved from a convex first position to a concave second position to provide a hand-held bottle. Each plate incorporates a toothed "reversible" center. Such containers, by having two large, flat opposing sides, differ in vacuum pressure stability from hot-fill containers, which tend to maintain a generally cylindrical shape under vacuum pull. The enlarged panel sidewalls experience increased suction and sink more than would occur if the panels were smaller in size than would occur in a "standard" construction, which is in a generally circular shape. Six plates are included on the container. Thus, such a container structure increases the force applied to the two plates, thereby enhancing the effective bending force.

Even so, the raised portion of the plate must remain relatively flat, or the vacuum force will not be able to pull the plate to the desired concavity. The need to maintain a shallow arch to allow for bending was previously disclosed by Krishnakumar et al. in US Patent No. 5,303,834 and US Patent No. 5,908,128. This limits the amount of vacuum force that is removed before the container walls are strained. Additionally, it is generally believed that a shape that is convex in both the longitudinal and horizontal planes is in any case unlikely to be successfully inverted unless it is very shallowly convex. Still further, if there is a sufficient amount of protrusion on the plates, the plates cannot return to their original raised position again due to the release of vacuum pressure when the cover is removed. At most, one plate will be "force-flipped" and locked into a new inverted position. The plate cannot reverse when there is no longer the influence of heat from the liquid to soften the material and sufficient force cannot be obtained from ambient pressure. Also, there is no longer the aid of memory that can be obtained from plastic before being snapped into a recessed position. US Patent 5,908,128 to Krishnakumar et al. previously disclosed the provision of longitudinal ribs to prevent such permanent deformation as the arc of the panel bends from a convex position to a concave position. The same observation on permanent deformation is also disclosed in US Patent No. 5,303,834 to Krishnakumar et al. US Patent No. 4,877,141 to Hayashi et al. also discloses the need to keep the panels relatively flat if they are bent in a direction opposite to their natural arc.

The applicant considers that the main form of failure in prior art containers is when there is a vacuum pressure inside the container, and especially when such containers are commercially advantageous to reduce the material weight, resulting in impossibility of the container geometry due to weakness. Restored deformation.

On the contrary, the present invention allows for increased bending of the side walls of the vacuum panel so that the pressure acting on the container can be more easily withstood. Ribs of various types and locations as described above may still be employed so as to still compensate for any excessive stresses during bending of the vessel wall to the new "pressure regulation" condition by the environmental forces. These stresses inevitably exist.

Contents of the invention

It is therefore an object of the present invention to overcome or at least reduce this problem with current containers, or at least to provide the public with a useful choice.

Further objects of the present invention will appear from the following description.

According to one aspect of the present invention, there is provided a container having a central longitudinal axis, said container comprising at least one reversible, bendable panel having at least one protrusion from a plane in one direction part, said plane being arranged relative to said longitudinal axis, said bendable plate further comprising at least one actuation portion having a lesser convexity in said direction, whereby in use, deflection of the actuation portion results in a bendable deflection of the rest of the board.

In a preferred form, the protrusion is in an outward direction relative to said plane.

In another preferred form, the protrusion is in an inward direction relative to said plane.

In one preferred form, the bendable plate may be generally arcuate.

In an alternative form, the bendable plate may comprise two bendable plate portions converging at a vertex.

Preferably, a bendable plate may be located between relatively inflexible bonded regions.

In a preferred form the or each activation portion may be located substantially at one end of the bendable plate.

In an alternative preferred form, the activation portion may be located generally near the center of said flexible plate.

Preferably, the or each activation portion may comprise a generally planar portion.

Preferably, the flat portion may be located at the distal end of the activation portion relative to the rest of the bendable plate.

In a preferred form, the or each activation portion may project in a direction away from the remainder of the bendable plate.

Preferably, the boundary between the activation portion and the remainder of the bendable plate may be substantially arcuate in the circumferential direction of the plate.

In a preferred form, the degree of convexity of the bendable plate may gradually increase in a direction away from said activation portion.

In an alternative form, the convexity of the bendable plate may remain substantially constant in a direction away from said activation portion.

Preferably, said container may comprise a connecting portion between said bendable panel and said joining region, the connecting portion being adapted to position said bendable panel and said joining region at different positions relative to the center of the container. on the circumference of .

Preferably, the connecting portion may be substantially "U"-shaped, wherein the side of the connecting portion facing the bendable plate is adapted to be bent such that the "U" shape is substantially straightened when the bendable plate is in the first position, and when The bendable panel returns to a "U" shape when inverted from the first position.

Preferably, the convexity of the activation portion may be adapted to allow deflection of the activation portion when a predetermined liquid introduced into the container at a predetermined temperature cools.

Preferably, the bendable plate is adapted to be reversed in use due to flexing of the activation portion.

According to another aspect of the present invention there is provided a controlled deflection bendable panel having an activation region of predetermined convexity and a more convex flexure region extending from said activation region, Thus, deflection of the bendable plate occurs in a controlled manner as the pressure of the vessel changes.

According to a further aspect of the present invention, there is provided a controlled deflection bendable panel for a hot-fillable container having a portion with an activation area of a predetermined degree of convexity and a spring from said progressively more convex curved regions extending from the actuation region, the wall flexing outwardly between said regions such that the deflectable panel deflects between said regions in a controlled manner in response to changes in vessel pressure Happened gradually.

Preferably, a flat region may extend between said non-bendable regions, forming the end of said activation portion.

According to another aspect of the present invention there is provided a controlled deflection bendable panel having an activation region of a predetermined degree of convexity and a bending region of lesser convexity in a direction opposite the activation region , the flexure region extends from said activation region such that the flexure plate flexes in a controlled manner in response to changes in vessel pressure.

According to a further aspect of the present invention, there is provided a controlled deflection bendable panel for a hot-fillable container having a portion with an activation area of a predetermined degree of convexity and a spring from said progressively less convex curved regions extending from the actuation region between which the wall flexes inwardly so that the curved plate responds gradually in a controlled manner to changes in vessel pressure between said regions produce deflection.

In a preferred form, the activation region and/or the bending region may be generally arcuate.

In an alternative preferred form, the activation region and/or the flexure region may comprise two plate portions converging at a vertex.

Other aspects of the invention will become apparent from the following description, given by way of example with reference to the accompanying drawings.

Description of drawings

Figure 1 shows a front view of a container according to a possible embodiment of the invention.

Figure 2a shows a front view of a panel of the container shown in Figure 1 .

Figure 2b shows a side view of the plate shown in Figure 2a.

Figure 3 shows a reversed side view of the plate shown in Figure 2b.

Figures 4a-c are schematic views showing the cross-section along line A-C of the container of Figure 1, respectively, when the plate portion is not inverted.

Figures 5a-c respectively show schematic views of the section of the container of Figure 1 along the line A-C when the plate is inverted.

Figures 6a-c show front and side views of an alternative embodiment of the plate.

Figure 7a shows a front view of another alternative embodiment of the plate.

Figures 7b-c show side views of the plate portion of Figure 7a in uninverted and inverted positions, respectively.

Figure 8a shows a front view of another embodiment of the plate.

Figures 8b-d show side views of the plate portion of Figure 8a in non-inverted, partially inverted and fully inverted positions, respectively.

Figures 9a-c and d-f respectively show a schematic view of a section along the corresponding line A-C of the container shown in Figure 1 with another alternative plate portion in the uninverted and inverted positions respectively.

Detailed ways

Referring to Figure 1, according to a preferred form of the invention, a container generally indicated by the numeral 1 has a main side wall portion 2 of generally cylindrical shape.

Container 1 is an adjustable pressure container, in particular a "hot fill" container suitable for filling liquids at a temperature above room temperature. The container 1 may be blow molded and may be made of polyester or other plastic material, such as heat-set polyethylene terephthalate (PET). The lower portion of the side wall portion 2 comprises a plurality of vertically oriented elongated vacuum panels 3 arranged on the circumference of the container, separated from each other by smooth vertically elongated joining regions 4 . The plates may be generally rectangular in shape and adapted to bend inwardly when the container is filled with hot filling liquid, covered and the liquid subsequently cooled. During this process, the vacuum panel 3 operates to compensate for the hot-fill vacuum.

FIG. 2 a shows the vacuum panel 3 of the container 1 . The vacuum panel 3 comprises at least one connecting portion 7 connecting a raised portion 5 to the bonding area 4 . The raised part 5 includes an activation part 8 which controls the engagement of the raised part 5 and the connecting part 7 . Preferably, the connecting portion 7 can be relatively easily bent inwardly under the action of the vacuum force, and the actuating portion 8 deflects the raised portion 5 by inversion and further inward bending. This results in a larger volume displaced by the vacuum panel 3 than with existing curved panels. The vacuum pressure is thereby reduced considerably compared to prior art containers, which results in less stress being applied to the side walls of the container.

Preferably, the connection portion 7 allows a radius from the center of the container 1 at the edge of the curved plate 3 (inside the connection portion 7 ) to be independent of the radius at the edge of the bonding area 4 (around the outside edge of the connection portion 7 ). Thus, the connecting portion 7 allows the joining portion 4 to be completed independently on one side, and the curved plate 3 to be completed on the other side and is most suitable for flexing. This connecting portion 7 transitions any difference in radius between the two structures.

The border 8A between the activation portion 8 and the rest of the raised portion 5 is shown as being generally arcuate in the circumferential direction of the plate 3 .

The amount of protrusion or curvature of the activation portion 8 relative to the plane defined by the central longitudinal axis of the container is significantly less than that of the raised portion 5, making it more susceptible to vacuum pressure. The activation portion 8 further includes a very flat activation end 9 which is most susceptible to vacuum pressure. Therefore, when the container 1 is subjected to vacuum pressure, the vacuum panel 3 can bend at the activation end 9, then the entire activation portion 8 flexes and then reverses, and then the raised portion 5 reverses. In an alternative embodiment, the activation end 9 may be recessed. However, in this embodiment the convexity of the concave portion relative to the plane defined by the longitudinal axis of the container is still less than the convexity of the rest of the convex portion 5 .

It can be understood that the inversion of the raised portion 5 can be performed stably during the cooling process as the volume of the contents of the container 1 gradually shrinks. This is in contrast to a board that "jumps" between two states. Compared to a "jumping" plate, the raised portion 5 gradually deflects into and out of the inversion under a relatively small pressure difference, which means that less force is transmitted to the container 1 side wall. This results in less material having to be used in the construction of the container, making the product less expensive.

Thus, for the same amount of container material, there are fewer failures under load.

In addition, the reduction in the pressure difference required to invert the raised portion 5 allows a greater number of plates 3 to be included in one container 1 . The plate 3 also does not need to be very large in size since only a low vacuum force needs to be provided to initiate the bending of the plate. Therefore, the size of the plate 3 does not need to be large, nor does it need to reduce its number in the container structure, so that the design of the container is more flexible.

Fig. 2b shows a sectional view along line DD in Fig. 2a. The raised portion 5 of the plate 3 is shown in an uninverted position, the dotted lines demarcating the boundaries of the raised portion 5 with the connecting portion 7 . In a preferred form of the invention, raised portion 5 is generally arcuate in an outward radial or transverse direction, as indicated by arrow 6 . The connecting portion 7 is substantially "U"-shaped, and the relative heights of the sides of the "U" shape determine the relative radii of the locations where the bonding area 4 and the protruding portion 5 are located. With the least convexity, ie having the smallest curvature of the raised portion 5, the activation end 9 is most susceptible to vacuum pressure.

Figure 3 shows a plate 3 with the raised portion 5 inverted due to the application of vacuum pressure. The activation end 9 and activation portion 8 first flex and invert, effectively pulling the adjacent area of raised portion 5 inwards. This action continues along the raised portion 5 until the raised portion is completely inverted as shown in Figure 5b. The dotted line in FIG. 3 indicates the edge of the raised portion 5, and the dotted line 5a indicates the position of the raised portion 5 when not inverted.

Importantly, when the vacuum pressure is released following removal of the closure from the container, the plate 3 can recover from its vacuum position, returning to its original shape. A uniform gradient of curvature from one end of the raised portion 5 to the other facilitates this variation. The curvature of the curvature gradually increases in the direction away from the activation portion 8 . Alternatively, the raised portion 5 may have a substantially constant transition. When the pressure is released, the activation portion 8 successfully reverses the inwardly bowed plate 3 laterally, initially the reversal of the activation portion 8, followed by the swelling of the raised portion 5, without irreversible deformation. The vacuum panel 3 can be reversed repeatedly without significant permanent deformation.

Figures 4a-c show cross-sectional views of the container shown in Figure 1 along lines AA, BB, CC, respectively, wherein the raised portion 5 is in an uninverted position. In this preferred embodiment, the raised portion 5 is gradually further raised outwardly in a direction away from the activation portion 8 .

Figures 5a-c show cross-sectional views of the container 1 along lines AA, BB, CC, respectively, where the raised portion 5 in 5b is in a fully inverted position due to the application of vacuum pressure. The area near the line AA of the raised portion 5 is relatively more deflected than the area near the activation portion 8 . The dotted line 5a in Figures 5a-c marks the position of the raised portion 5 in the absence of vacuum pressure.

FIG. 6 a shows a front view of an alternative embodiment of a vacuum panel 30 having an activation portion 80 and a flat area 90 . The connecting portion 70 of the vacuum panel 30 is a planar member surrounding the raised portion 50 . Figure 6b shows the vacuum panel 30 without vacuum pressure applied. In a direction away from the activation area 80 , the raised portion 50 has a substantially constant arc in the direction of the arrow 6 . Figure 6c shows the vacuum plate 30 with the raised portions 50 in a fully inverted position due to the application of vacuum pressure.

FIG. 7 a shows a front view of another alternative embodiment of a vacuum panel 300 . The vacuum panel 300 includes two convex portions 500 adjacent in the vertical direction. The activation portion 800 extends in two directions from the central activation end 900 . In this embodiment, the center of the vacuum panel 300 is most susceptible to flexing under vacuum pressure and therefore flexes first. Figures 7b and 7c show the vacuum panel 300 with no pressure applied and the vacuum panel 300 in a fully inverted position, respectively.

Dotted line 800a represents the arcuate boundary between activation portion 800 and the remainder of raised portion 500 .

Figure 8a shows a front view of another alternative embodiment of a vacuum panel, generally indicated by arrow ³⁰⁰¹ . The vacuum panel 300 ¹ comprises two vertically adjacent raised portions 500 ¹ and 500 ¹¹ each having an activation portion 800 ¹ including a central flat area 900 ¹ therebetween. However, unlike the vacuum panel 300, the normal position of one of the raised portions 500 ¹¹ is concave rather than convex (see Fig. 8b). Upon hydraulic action, the concave raised portion 500 ¹¹ is reversed in the direction of arrow 6a (see FIG. 8c ), reducing the pressure on the connection area ( 4 ) between adjacent plates 300 ¹ . Once the fluid cools, the vacuum pressure causes both raised portions ⁵⁰⁰¹ and ⁵⁰⁰¹¹ to reverse in the direction of arrow 6B (see Figure 8d).

It should be understood that the shape and/or configuration of the vacuum panels may vary. For example, as shown in Figure 9, the container (1) may have a vacuum panel with a raised portion ⁵¹ comprising two planar portions 10 converging at an apex 11 so as to form an angled rather than Arched board. Figures 9a-c show sections along the lines AA, BB and CC, respectively, of the container 1 of Figure 1 with such a raised portion ⁵¹ . Figures 9d-f show the inverted position of the raised portion ⁵¹ of Figures 9a-c, respectively, wherein the solid line ^51b indicates the inverted position and the dotted line ^51a indicates the position before inversion. Additionally, or alternatively, the panels 3 of any embodiment may be arranged transversely to the longitudinal axis of the container 1 rather than vertically as exemplarily shown in FIG. 1 .

Accordingly, the present invention provides an adjustable pressure container that incorporates bendable panels that allow for greater variation in the volume of the container, thereby reducing the pressure exerted on the side walls. As a result, the amount of material required to support the container as a whole is reduced, so that the container can be manufactured more cheaply.

Where in the foregoing description, reference has been made to specific elements or integers of the invention, which have known equivalents, these equivalents are also encompassed by the invention as if individually described herein.

Although the invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims (26)

1. A container having a central longitudinal axis, said container comprising at least one reversible, bendable panel having at least one portion raised in one direction from a plane, said plane Arranged relative to said longitudinal axis, said bendable panel further comprises at least one activation portion which is less convex in said direction, so that in use, deflection of the activation portion causes deflection of the remainder of the bendable plate. song. 2. A container as claimed in claim 1, wherein the protrusion is in an outward direction relative to said plane. 3. A container as claimed in claim 1 or 2, wherein the protrusion is in an inward direction relative to said plane. 4. A container as claimed in claim 1, 2 or 3, wherein the bendable panel is generally arcuate, the actuation portion having a smaller arc of curvature than the remainder of the bendable panel. 5. A container as claimed in claim 1, 2 or 3, wherein the bendable panel comprises two bendable panel portions which converge at a vertex. 6. A container as claimed in any one of claims 1 to 5, wherein a bendable panel is located between relatively inflexible joining regions. 7. A container as claimed in claim 6, wherein the or each activation portion is located substantially at one end of the bendable panel. 8. The container of claim 6, wherein the activation portion is located generally near the center of the flexible panel and between two flexible panel portions extending therefrom. 9. The container of claim 6, wherein each activation portion includes a generally planar portion. 10. A container as claimed in claim 9, wherein the flat portion is located at the distal end of the activation portion relative to the remainder of the flexible panel. 11. A container as claimed in claim 1, wherein each activation portion is at least partially convex in a direction away from the remainder of the flexible panel. 12. The container of claim 6, wherein the boundary between the activation portion and the remainder of the flexible panel is generally arcuate along the circumference of the panel. 13. The container of claim 6, wherein the degree of convexity of the bendable panel gradually increases in a direction away from the activation portion. 14. The container of claim 6, wherein the degree of protrusion of the bendable panel is substantially constant in a direction away from the activation portion. 15. The container of claim 6, comprising a connecting portion between said bendable panel and said bonding area adapted to place said bendable panel and said bonding area relative to the The centers are located on different circumferences. 16. A container as claimed in claim 15, wherein the connecting portion is generally "U" shaped and the side of the connecting portion opposite the bendable panel is adapted to be bent, in use when the bendable plate is in the first The "U" shape is generally straightened in position and returns to the "U" shape in use when the bendable panel is reversed from the first position. 17. The container of claim 6, wherein the protrusion of the actuation portion is adapted to allow deflection of the actuation portion when a predetermined liquid introduced into the container at a predetermined temperature cools. 18. A container as claimed in claim 6, wherein the bendable panel is adapted to be reversed in use by flexing of the activation portion. 19. A controlled deflection bendable plate having an actuation region of predetermined convexity and a more convex flexure region extending from said actuation region such that, as a function of vessel pressure , the deflection of the bendable plate occurs in a controlled manner. 20. A controlled deflection bendable panel for a hot fillable container having a portion with an activation area of a predetermined degree of convexity and a raised area extending from said activation area Regions of progressively increasing curvature between which the wall flexes outwardly such that deflection of the bendable panel between said regions occurs in a controlled manner in response to changes in vessel pressure. 21. A controlled deflection bendable plate having an activation region of predetermined convexity and a bending region of lesser convexity in a direction away from the activation region, the bending region extending from said The activation region is extended so that the flexure plate flexes in a controlled manner in response to changes in vessel pressure. 22. A controlled deflection bendable panel for a hot fillable container having a portion with an activation area of a predetermined degree of convexity and a raised area extending from said activation area There are regions of progressively decreasing curvature between which the wall flexes inwardly so that the curved plate flexes gradually between said regions in a controlled manner in response to changes in vessel pressure. 23. A controlled deflection bendable panel as claimed in any one of claims 19 to 22, comprising a pair of substantially inflexible regions, said activation region and said bending region extending therebetween a A flat region between said non-bendable regions forms an end of said activation region. 24. A controlled deflection bendable panel as claimed in any one of claims 19 to 22, wherein the activation region and/or the bending region are generally arcuate. 25. A controlled deflection bendable panel as claimed in any one of claims 17 to 22, wherein the activation region and/or the flexure region comprises two panel portions converging at a vertex. 26. A container as herein described with reference to 1 to 5, 6, 7, 8 or 9 of the accompanying drawings.

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