BG65326B1 - A container having pressure responsive panels - Google Patents

Abstract

A container (1) suitable as hot-fill container, includes a controlled deflection flex panel (3) which may invert and flex under pressure, such as hot-fill conditions, to avoid deformation and permanent buckling of the container (1). The flex panel (3) includes an initiator portion (8) which has lesser projection than the remainder of the flex panel (3) and initiates deflection of the flex panel (3).

Description

(54) CONTAINER CONTAINING PANELS

Technical field

The invention relates to a pressure-adjustable container, and in particular to polyester containers which can be filled with hot liquid.

BACKGROUND OF THE INVENTION

Hot-fill applications exert considerable and complex mechanical stress on the container structure due to thermal stress, hydraulic filling pressure, and immediately after closing and vacuum pressure when the fluid cools.

Thermal stress is exerted upon the introduction of hot fluid into the container walls. The hot fluid causes the walls of the container to soften and then shrink unevenly, causing deformation of the container. Therefore, the polyester must be hot-worked to induce molecular changes, resulting in the container exhibiting thermal stability.

The side walls of the heat-resistant container are subjected to pressure and tension during the filling process and also for a considerable period of time thereafter. When the container is filled with hot liquid and closed, there is initial hydraulic pressure and increased internal pressure is exerted on the containers. When the liquid and the air space under the lid are subsequently cooled, a thermal contraction occurs with partial evacuation (emptying) of the container. The vacuum created by this cooling tends to deform the container walls mechanically.

Containers that include multiple longitudinal flat surfaces are easier to adapt to vacuum. Agrawal et al. in US 4 497 855 discloses a container with a plurality of concave, pliable panels separated by equal sections, allowing uniform deformation inward under vacuum. The effects of vacuum are controlled without adversely affecting the appearance of the container. The panels are pulled inwards to remove the internal vacuum and thus to prevent excessive force applied to the container structure, which would otherwise deform the structures with a rigid support or a flat section. The amount of "bending" available in each panel is limited, and when the limit is reached, there is an increased amount of effort that is transmitted to the side walls.

To reduce the effect of the force transmitted to the side walls, most prior art solutions are directed to providing reinforcing portions in the container including panels to prevent the deformation of the structure by the force of the vacuum.

The prediction of horizontal and vertical annular sections or ribs through the container has become a common practice in container construction and is not limited to hot-filled containers. Such annular sections enhance the portion to which they are attached. US 4 372 455 to Cochran discloses a longitudinally extending annular rib placed in the regions between the planar surfaces which are subjected to vacuum deforming hydrostatic forces. Akiho Ota dr. in U.S. Pat. No. 4,805,788 discloses longitudinally arranged ribs along the panels to increase the stiffness of the container. Akiho Ota also reveals the amplifying effect of providing a greater footing in the countries of the equal stretches. This provides a larger size and strength of the rib sections between the panels. Akiho Ota et al. in US 5 178 290 discloses recesses for reinforcing panel sections per se.

Akiho Ota et al. in US 5 238 129 discloses additional reinforcement with an annular rib, which at the same time is oriented horizontally in strips above and below and beyond the hot-filled panel portion of the bottle.

In addition to the need to strengthen the container against thermal and vacuum, there is a need to take into account the initial hydraulic pressure and the increased internal pressure that

65326 Bl exerts pressure on the container when hot fluid is introduced, followed by closure. This causes a voltage that is transmitted to the side wall of the container. There is a forced movement out of the heated panels, which can cause the container to swell.

So Hayashi et al. in U.S. Pat. No. 4,877,114 discloses a panel configuration that is adapted to the initial and natural bending outward, caused by internal hydraulic pressure and temperature, followed by inward bending caused by the formation of a vacuum during cooling. It is important that the panel is kept relatively flat in profile, but with a slightly offset central part, to increase the stability of the panel, but without preventing its radial movement in and out. But since the panel remains generally flat, the amount of traffic is limited in both directions. Panel fins are not necessarily included for additional flexibility as this would prevent backward and outward movement of the panel as a whole.

Krishnakumar et al. in U.S. Pat. No. 5,908,128 discloses another flexible panel that is designed to respond to hydraulic pressure and temperature forces that result from filling. A relatively standard geometry of a "hot-filled" container for "pasteurizing" containers is disclosed. It is claimed that the pasteurization process does not require the container to be preheated before filling, since the liquid is introduced cooled and heated after closure. They are used along the face panels to compensate for differences in pressure. However, to provide flexibility in radial outward movement, followed by radial inward movement, the panels are kept slightly (shallowly) bent inwards, for adaptation due to changes in internal pressure and temperatures during the pasteurization process. Increasing the temperature after closing, which is maintained for a certain period of time, causes the plastic material to soften and thus the curved panels can bend more easily under the influence of the force that has arisen. However, it is revealed that too much of a bend would prevent this. Permanent deformation of the panels, when pushed in opposite bending, is avoided by shallow bending and also by softening the material when heated. The amount of force transmitted to the walls of the container is therefore again determined by the amount of bending existing in the panels, just as with a standard hot-filled bottle. However, the amount of bending is limited, which is due to the need to preserve the weak (shallow) curvature of the radial profile of the panels. Accordingly, the bottle is strengthened in many standard ways.

Kshnakumar et al. in U.S. Pat. No. 5,303,834 further discloses "flexible" panels that can be moved from a convex position to a concave position to provide a "collapsible" container. Vacuum pressure alone cannot invert panels, but they can be manually pushed into an inverted (inverted) position. The panels automatically "bounce" back to their original shape upon release from the compression pressure, as considerable force is required to maintain them in the inverted position and must be maintained manually. Permanent deformation of the panel caused by the initial convex position is avoided by the use of multiple points of bending.

Krishnakumar et al. in U.S. Pat. No. 5,971,184 discloses further "flexible" panels, which are claimed to be movable from a convex first position to a recessed second position, to provide a gripping bottle having two wide flat sides. Each panel includes a recessed "invertible" central part. Containers, such as those with two large and flat opposite sides, differ in vacuum pressure stability from hot-filled containers, which are designed to hold a generally cylindrical vacuum-withdrawal shape. The enlarged panel side walls are subjected to increased suction and are drawn into the recessed form more than if each panel was smaller in size, which is obtained in a "standard" configuration containing six panels in a substantially cylindrical container. Thus, such panel construction increases the value of the force applied to each of the two panels,

65326 Bl thereby increasing the value of the bending force available.

Even so, the convex part of the panels must still be kept relatively flat or the vacuum will not be able to pull the panels in the required concave shape. The need to retain a shallow arc to allow bending is described in advance by Krishnakumar et al. in US 5 303 834 and US 5 908 128. This in turn limits the value of the vacuum force that is released before exerting force on the walls of the container. In addition, it is generally considered impossible for a shape that is convex in both the longitudinal and horizontal planes to be successful in any way by the inverter, unless it is of very light (shallow) convexity. However, on the other hand, the panels cannot then be reverted back to their original convex position again when the pressure is released from the vacuum when the cap is removed, if there is a significant amount of convexity of the panels. At best, the panel will undergo a “roll-over” and bounce to a new inverted position. It is then impossible to turn the panel in a direction, since there is no longer any effect of heating from the fluid to soften the material and there is insufficient force from the surrounding pressure. Additionally, there is no longer any support from the stored force that exists in the plastic before it is turned into a concave position. Krishnakumar et al. in US 5 908 128 previously disclosed providing longitudinal ribs to prevent such permanent deformation occurring when the panel arches are bent from a convex position to a concave position. The same observation regarding permanent deformation is also disclosed in US 5 303 834 by Krishnakumar et al. Hayashi et al. U.S. Pat. No. 4,877,114 also discloses the need to keep panels relatively flat if they are bent against their natural curvature.

EP 0 505 054 discloses a hot-filled plastic container with invertible, vacuum-deformable surfaces at gripping points. The container has opposite gripping portions in the side wall that allow the container to be grasped between the thumb and fingers of one hand to facilitate handling and pouring of the container from the container. Each hand grasping area includes an outwardly projecting region with an outer edge and an integral hinge, allowing opposing convex areas to invert and to bend inward to one another. In this way, they take on an internal effort that seeks to deform the sidewall of the container inward due to the filling of the container with liquid at elevated temperature and subsequent cooling of the liquid. The known solution discloses flexible panels that are convex in two planes and are circumferentially circumscribed by a hinged section that extends inwards.

In this known embodiment, since a longitudinal and transverse projection is required when vacuum pressure is formed, this will cause inversion resistance and the inability to provide a gradual, controllable bending in response to emerging stresses in the hot-fill container. The hinge mechanism used not only does not allow for smooth and gradual bending, but also creates a bounce reaction in the inverted position.

Another embodiment of a hot-filled container is known from US 5341946, which includes a plurality of elongated, vertically oriented absorption panels. Each of the panels has a central projecting projection, which is divided into upper and lower portions by a transverse edge. The panel sections are connected at the top and bottom by means of bent out sections. Ring-shaped reinforcing edges are provided in the side wall above and below the vacuum panels, which provide additional support for the upper and lower edges of the vacuum panels.

EP 0 279 628 discloses a pressure-resistant container shaped as a bottle comprising panels surrounded by sheets. Each panel has voltage-absorbing strips covering the top points, recessed from the outer surface of the panel to the inside of the container, and folding lines in the shape of "V" and "V-inverted".

65326 Bl

The last two solutions cited also cannot provide a smooth and progressively controlled bending in the event of stresses, thus avoiding the effective deformation of hot filling and cooling afterwards.

A fundamental type of damage to containers in the prior art is the irreversible alteration of the structural geometry of the container, which is due to instability; when there is a vacuum pressure inside the container, and in particular when such a container is subject to weight loss of the material for commercial advantage.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a container with pressure-sensitive panels to improve the adaptability of the container in the event of stresses in the container under conditions of hot filling and to avoid deformation and deformation.

The task is accomplished by a container suitable for accommodating a fluid and comprising at least one flexible controllable bending panel for adjusting to a pressure change occurring in the container. The flexible panel is of longitudinal and transverse dimensions, referring to the longitudinal axis of the container and defining the plane of the flexible panel. The flexible panel has at least one bending region projecting outward from the plane. An initiating bending area is provided. The initiation region of bending has a smaller size of arcuate projection extending outward from said plane compared to the region of bending and at a distance from the latter. The initiating region and the bending region are fused longitudinally with each other within the panel so that the initiating region can bend inwardly with respect to said plane and, in response to pressure changes, the arc size changes and causes the bending region to bend progressively, as a reaction to the increase in pressure changes in the container.

In one embodiment, the bending initiation region is positioned toward the first longitudinal end of the flexible panel.

Preferably, the bending region is positioned toward the opposite longitudinal end of the flexible panel.

The container has a longitudinal axis and the bending portion extends outwards in a transverse direction to the longitudinal axis of the container.

Preferably, the bending of the bending region causes the outer arch of the projection out of the bending region to be reduced.

Preferably, the bending initiating region also has a projection outward which merges smoothly with the bending region and increases progressively from the initiating region to the bending region.

In one embodiment, the bending initiating region has an arched projection outward, which merges smoothly with the bending region and progressively decreases from the initiating region to the bending region.

The size of the arc relative to said plane varies along the axis of the container.

The initiation region can be varied in transversally extending size along the longitudinal axis of the container.

The folding area can be varied in a transversely extending dimension along the longitudinal axis of the container.

Preferably, the initiating region of the inverter is inverted in a curvature, in response to a change in the vacuum pressure inside the container.

Preferably, the bending region is also inverted so as to turn in a curvature, in response to a change in the vacuum pressure inside the container.

The container can have at least 2, 3, 4, 5 or 6 panels.

In another possible aspect, the container is adapted to accommodate liquid at a temperature in excess of room temperature, wherein the container includes a wall defining a plane with at least one flexible panel. The flexible panel is configured to bend when the internal pressure changes during the temperature change of the liquid, the bending region projecting from said plane is located along the longitudinal axis of the container. The bending region is positioned toward the first longitudinal end of the flexible panel, and at least

65326 Bl an initiating bending region is positioned relative to the bending region toward the opposite longitudinal end of the flexible panel. The initiating region is adapted in use to rotate in the direction of its projection, thereby causing the bending region to rotate in the direction of its projection.

The flexible panel may be configured to bend inwards when the internal pressure is lowered while the liquid is cooled.

Preferably, the projection is in the outward direction with respect to said plane.

The flexible panel, when used, is adapted to bend outward as internal pressure increases as the liquid is heated.

The projection may be in the inward direction with respect to said plane.

The wall may comprise a plurality of flexible panels spaced along the longitudinal axis of the container.

The flexible panel or any flexible panel may include one or more substantially central initiating bending region (s) and a pair of bending regions extending beyond the initiating region (s) to opposite longitudinal edges of the wall.

In another possible embodiment, the flexible panel has a first and a second bending region extending over a false distance from the initiating portion, the first bending region extending to the first end of the flexible panel and the second bending region extending to the opposite end of the flexible panel. In this case, the initiating region is positioned closer to the center of the flexible panel than to each longitudinal end, thereby controlling and flexibly flexing the flexible panel, in response to a change in pressure in the container.

The container may include a wall with at least one flexible bent panel. In this case, the bending region has a progressively increasing arc size extending longitudinally from the initiating region and the wall bends outward between the region.

The container may include a pair of substantially unbending portions between which the initiating region and the bending region extend, and a flat portion extending between the non-bending portions to provide an end portion of the initiating region

The initiating area and / or the bending region may include two panel portions occurring at the top (either).

The container according to the present invention allows for increased bending of the side walls of the vacuum panel so that pressure on the container can be more easily absorbed. Reinforcing ribs of different types and locations, as described above, may also be used to compensate, on the other hand, for any overvoltage that must inevitably exist from collapsing the walls of the container in the new, pressure-adjusted, position from the forces of the environment.

Explanations of the annexed figures

Further aspects of the invention are elucidated by the following description, given by way of example only, with reference to the accompanying drawings, to which:

Figure 1 shows a vertical plane view of a container according to a possible embodiment of the present invention;

Figure 2a shows a view in vertical plane of a panel portion of the container shown in Figure 1;

Figure 2b - shows a side view of the panel portion shown in Figure 2a;

Figure 3 shows a side view of the panel portion shown in Figure 2b but inverted;

Figure 4a-c shows schematic views of the cross-sections of the container of Figure 1 along lines A-C, respectively, when the panel portions are not inverted;

Figure 5a-c shows schematic views of the cross-sections of the container of Figure 1 along lines A-C, respectively, when the panel sections are inverted;

Figure bass - shows front and side views of an alternative embodiment of a panel section;

Figure 7a shows a front view in the vertical plane of an additional alternative embodiment of a panel section;

65326 Bl

Figure 7b, c shows side views of the panel portion of Figure 7a in the non-inverted and inverted positions, respectively;

Figure 8a shows a front view in the vertical plane of an additional alternative embodiment of a panel section;

Figure 8b-d shows side views of the panel portion of Figure 8a in a non-inverted, partially inverted and fully inverted position, respectively;

9a-c and 9d-f show schematic cross-sectional views across lines corresponding to A-C, respectively, of the container of Figure 1 having an alternative panel portion, respectively, in the non-inverted and inverted positions.

Examples of carrying out the invention

In FIG. 1 according to a preferred embodiment of the present invention, the container is generally referred to as 1 having a main lateral wall portion 2 having a substantially circular cylindrical shape.

Container 1 is a pressure adjustable container, in particular a "hot-filled" container, which is adapted to be filled with liquid at a temperature above room temperature. The container 1 can be molded and can be made of polyester or other plastic material, such as hot-linked polyethylene terephthalate (PET). The lower part of the side wall 2 includes a plurality of vertically oriented, elongated flexible panels 3, which are arranged along the perimeter of the container 1 apart from smooth vertical elongated equal portions 4. Each panel may be substantially rectangular shape and be adapted to bend inwards when filling the container with hot filling fluid, closing the container and subsequently cooling the liquid. During the process, the flexible panels 3 act to compensate for the vacuum from the hot filling.

Figure 2a shows a flexible panel 3 of the container 1. The flexible panel 3 includes at least one connecting portion 7 that connects a protruding portion (generally designated as a bending region) to equal portions 4. The projected bending region 5 includes an initiating bending region 8, which controls the binding of the protruding bending region 5 and the coupling portion 7. Preferably, the coupling portion 7 can be bent inward by a vacuum force with relative ease, and the initiating bending region 8 forces the protruding region of bending 5 to be bent by inversion and then bending further inward. This causes a much larger volume evacuation from the flexible panel 3 than the existing known flexible panels. Vacuum pressure is then reduced to a greater extent than existing containers, causing less pressure to be applied to the side walls of the container.

Preferably, the coupling portion 7 allows the radius from the center of the container 1 at the end of the flexible panel 3 (inside the coupling portion 7) to be determined independently of the radius at the end of the flat sections 4 (outside the edge surrounding the coupling portion). In this way, the connecting section 7 allows the flat section 4 to be independently completed on one side and the flexible panel 3 to be completed and optimized for bending on the other side. The coupling section 7 covers any peripheral radial difference between the two structures.

The boundary line 8A between the initiating bending region 8 and the projected bending region 5 is shown to be substantially arcuate by itself in the direction of the periphery of the panel 3.

The size of the arc or protrusion of the initiating bend region 8 relative to a plane defined by the central longitudinal axis of the container is significantly smaller than the size of the arc or protrusion of the protruding bend region 5, which makes it more sensitive to vacuum pressure. The initiation region 8 further includes an initiation end 9 that is predominantly flat and most sensitive to vacuum pressure. Thus, when the container 1 is subjected to a vacuum pressure, the flexible panel 3 can be bent into the initiation end portion 9, followed by a curvature and then inversion of the entire initiation region 8 and subsequent continuation of the inversion

65326 Bl the given bending region 5. In an alternative embodiment, the initiating end 9 may be concave. In this embodiment, however, the projection size of the concave portion relative to the plane defined by the central longitudinal axis of the container 1 is even smaller than the projection size of the rest of the projected bending region 5.

The inversion of the protruding bending region 5 may progress steadily as a result of the gradual contraction of the volume of the contents of the container 1 during cooling. This is in contrast to a panel that "flips sharply" between two states. The gradual curvature of the protruding area 5 to and from the inversion in response to a relatively small pressure difference compared to panels that "roll over sharply" means that less force is transmitted to the side walls of the container 1. This allows less material is appropriately used in the container construction, making production cheaper. As a consequence, less damage under load can occur with the same amount of container material.

The reduced pressure difference required to invert the projected bending region 5 allows a larger number of panels 3 to be included in a separate container 1. It is also not necessary for the flexible panel 3 to be large in size, since it is intended to be low vacuum force to initiate panel bending. Thus, the panels 3 do not need to be large in size in the panel structure, nor are they smaller in the container structure, which provides greater flexibility in the container construction.

Figure 2b shows a cross-section along line DD of Figure 2a. The panel is shown with the projected bending region 5 in its non-inverted position, the dashed line showing the boundary line of the projected bending region 5 with the connecting portion 7. In a preferred embodiment of the invention, the projected bending region 5 is substantially arcuate radially outwards or in the transverse direction as indicated by pointing arrow 6. The connecting section 7 is essentially a 'U' '-shaped shape with relative heights on the sides of the' U '-shaped shape defining the relative radius in which n positioned equal sections 4 and protruding bending region 5. The initiating end 9 is most sensitive to vacuum pressure due to the least release, i.e. has the smallest arch of the protruding bending area.

Figure 3 shows a flexible panel 3 with a protruding bending region 5 inverted by the applied vacuum pressure. The initiating end 9 and the initiating region 8 are first curved and inverted first, effectively pulling the adjacent portion of the protruding region 5 inwards. This continues along issued 5 until it is completely inverted, as shown by pos. 5b. The dashed line in FIG. 3 shows the edge of the protruding area 5, and the broken line 5a indicates the position of the last 5 when not inverted.

It is important that when the vacuum pressure is released due to the removal of the cap from the container, the panel allows it to recover from its vacuum position and return to its original configuration. This can be assisted by uniformly grading the curvature of the arc from one end of the projected bending region 5 to the other end, as the arc progressively (gradually) increases away from the initiating region 8. Alternatively, the projected bending region 5 may have substantially steady increase (gradation). When the pressure is released, the initiating region 8 causes the inwardly flexible panel 3 to reverse the direction successfully, beginning with the inversion of the initiating region 8 and followed by an increased release of the projected bending region 5 without being subjected to irreversible sweeping. The flexible panel 3 can be inverted repeatedly without significant permanent deformation.

Figures 4a-c show cross-sectional views of container 1 shown in figure 1 along lines AA, BB and CC, respectively, with a projected bending region 5 in the inverted position. In this preferred embodiment, the protruding region 5 extends progressively further outward from the initiation region 8.

Figures 5a-c show cross-sectional views of a container along lines AA, BB and CC, respectively, with a projected bending region 5 in.

65326 B1 completely inverted position 5b due to the vacuum pressure applied. The area of the protruding area 5 around line AA curves relatively large compared to the areas near the initiation region 8. The dashed lines 5a in Figures 5a-c indicate the position of the protruding areas 5 without vacuum pressure.

Figure 6a shows a front view in the vertical plane of an alternative embodiment of a flexible panel 30 with an initiating area 80 and a flat area 90. The connecting portion 70 of the flexible panel 30 is a planar (elementary) element surrounding the projected bending area 50. Figure 6b shows a flexible panel 30 without the vacuum pressure applied. The protruding bending region 50 has a substantially constant curve of curvature away from the initiating region 80 in the direction of arrow 6. Figure 6c shows a flexible panel 30 with its protruding region 50 in a completely inverted position due to the application of vacuum pressure.

Figure 7a shows a front view in the vertical plane of a further alternative embodiment of the flexible panel 300. The panel 300 includes two protruding bending regions 500 arranged vertically adjacent to each other. The initiation region 800 extends in two directions from a central location of the initiation end 900. In this embodiment, the center of the panel 300 is most sensitive to curvature under vacuum pressure and is therefore curved first. Figures 7b and 7c show the panel 300 without applied vacuum pressure and in a completely inverted position, respectively.

The dashed line 800a illustrates an arcuate boundary line between the initiating regions 800 and the rest of the issued bending regions 500.

Figure 8a shows a front view in the vertical plane of a further alternative embodiment of a flexible panel, generally indicated by arrow 300 ¹ . The panel 300 'includes two protruding bending regions 500' and 500 ¹¹ arranged vertically adjacent to each other, with corresponding initiation regions 800 * including a central planar region 900 ¹ between them. Unlike panel 300, the nominal position of one of the projecting regions 500 ¹¹ is more concave than convex (see FIG.

8c). When hydraulic pressure is applied, the concave section 500 ¹¹ is inverted in the direction shown by arrow 6a (see Figure 8c), reducing the pressure on the flat sections 4 between adjacent panels 300 '. As the fluid cools, the vacuum pressure causes the protruding regions 500 'and 500' ¹ to invert in the direction of arrow 6B. (see Figure 8d).

It will be noted that the profile and / or configuration of the panels can be modified. For example, as shown in Figure 9, the container 1 may have panels with protruding bending areas 5 comprising two flat portions 10, which meet at the top (either) 11, so as to form an angular panel as opposed to an arched panel. Figures 9cc show cross sections along lines AA, BB and CC, respectively, of container 1 of figure 1, but with such protruding bending regions 5 ¹ . Figures 9d-f show the inverted positions of the protruding regions 5 ¹ of Figures 9a-c respectively, depicting with whole lines 5'b the inverted position and with dashed lines 5'a the position before inversion. Additionally or alternatively, panels 3 of each of the exemplary embodiments may be arranged transversely to the longitudinal axis of the container 1 instead of vertically, as shown in Figure 1, for example.

In this way, a pressure-adjustable container comprising flexible panels is provided, which allows a large variation in the volume of the contents of the container and therefore reduced pressure is applied to the side walls. As a consequence, a reduced amount of material is required to maintain the integrity of the container and the container may thus be cheaper to manufacture.

Where reference is made to specific components or units of the invention having known equivalents in the foregoing description, then such equivalents are included herein as individually explained.

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

Claims (24)

Claims A container (1) having pressure-responsive panels suitable for accommodating a fluid and comprising at least one flexible panel (3) with adjustable curvature to adjust the pressure change caused by the container, wherein the flexible panel (3) has longitudinal and the transverse dimensions defining the plane of the flexible panel (3), the longitudinal and transverse dimensions being oriented towards the longitudinal axis of the container, and the flexible panel (3) having a bending region (5) extending outward from said plane, characterized in that that the panel (3) has flexible inserts the bending ator region (8), positioned longitudinally, away from the bending region (5), the initiating bending region (8) having a smaller arcuate projection extending outward from the plane compared to the bending region (5), in which the regions (8, 5) merge longitudinally within the panel (3) as the size of the arcuate projection increases progressively from the initiating region (8) to the bending region (5) so that the initiating region (8) ) can be bent inwards with respect to the plane and is in accordance with changes in pressure varying the size of the arched projection, causing the bending region (5) to decrease the size of its arch and to bend progressively in accordance with the increase in the change in pressure of the container (1). Container according to claim 1, characterized in that the bending region (5) is arranged outwards in the transverse direction with respect to the longitudinal axis. Container according to claims 1 and 2, characterized in that the bending of the bending region (5) causes the outer arch of the projection to be reduced, out of the bending region (5). Container according to Claims 1,2 and 3, characterized in that the initiating region (8) has a projection which fuses seamlessly with the bending region (5). Container according to Claims 1,2 or 3, characterized in that the initiator region (8) has a curvature inward, flowing smoothly with the bend region (5). A container according to claim 1, characterized in that the size of the arc relative to the plane is variable along the axis of the container (1). A container according to claim 1, characterized in that the initiating region (8) changes its transverse dimension along the longitudinal axis of the container (1). A container according to claim 7, characterized in that the bending region (5) changes its transverse dimension along the longitudinal axis of the container (1). Container according to Claim 7, characterized in that the initiator region (8) of the inverter is so inverted that it curves in accordance with the variation of the vacuum pressure inside the container (1). Container according to claim 9, characterized in that the bending region (5) of the inverter is so inverted that the curvature conforms to the variation of the vacuum pressure inside the container (1). A container comprising the features according to claim 1, wherein the container (1) is adapted to accommodate a liquid at a temperature in excess of room temperature, wherein the flexible panel (3) is adapted to bend when the internal pressure changes during a temperature change of the fluid, characterized in that the initiator region (8) is adapted to rotate in the direction of its projection, thereby causing the bend region (5) to rotate in the direction of its projection. A container according to claim 11, characterized in that the flexible panel (3) is adapted for inward bending while reducing the internal pressure during cooling of the liquid. Container according to claim 11 or 12, characterized in that the arcuate projection is outwards with respect to the plane of the panel (3). A container according to claim 13, characterized in that the flexible panel (3) is adapted for bending outwards in use, with an increase in internal pressure during the heating of the liquid. Container according to claim 11, characterized in that the arch of the projection is inwards with respect to the plane of the panel (3). 65326 Bl A container according to claim 11, characterized in that the container (1) comprises a plurality of flexible panels (3) spaced apart with respect to the longitudinal axis. A container according to claim 11, characterized in that each flexible panel (3) comprises one or more substantially central initiating bending region (s) and a pair of folding regions (5) ) extending from the initiating region (s) (8) to the opposite longitudinal edges of the flexible panel (3). A container according to claim 1, characterized in that the initiating bending region (8) is positioned closer to the center of the flexible panel (3), the flexible panel (3) having a first and second bending region (5) extending longitudinally from the initiating bending region (8), the first bending region (5) being disposed toward the first end of the flexible panel (3) and the second bending region (5) extending to the opposite end of the bending panel (3). A container according to claim 18, adapted to hold fluid at a temperature in excess of room temperature, characterized in that the initiating region (8) and / or the bending region (5) have an arched projection varying transversely along the axis of the container (1). 20. A container according to claim 19, characterized in that there are a pair of substantially non-folding regions between which the initiating bending region (8) and the bending region (5) extend, such as a flat region (900), between non-invasive areas to provide the end of the initiation area (8). Container according to claim 1, characterized in that the initiating region (8) and / or the folding region (5) comprises two panel parts (3) occurring at the top point (11). A container according to claim 1, characterized in that the bending region (5) is positioned toward the first longitudinal end of the flexible panel (3) and the initiator region (8) is positioned toward the opposite longitudinal end of the flexible panel (3). . 23. A container according to claim 1, characterized in that the initiating region (8) is projected outward from the plane to a lesser extent. A container according to claim 1, characterized in that the initiator region (8) is positioned closer to the first longitudinal end of the flexible panel (3). than the bending region (5).