Empty containers are wasteful of space, and transport, storage and disposal of containers, both before and after their intended use, can be greatly facilitated if the volume of the container can be reduced. Thus, although this invention is primarily directed to providing for the collapsing of containers after use, thus providing for improved waste disposal, the invention also contemplates the possibility that, under certain conditions, the containers may be collapsed before use, for assisting transport and storage.

A widely used form of container is a can serving to contain a material which must be protected against deformation and/or which is pressurised. In either function the can serves to protect the contents by providing a degree of resistance to distortion whether arising from the interior of the can or from outside the can. While this resistance is required when the can and its contents is being stored complete it can present problems when the can has to be disposed of having been opened and the contents removed. While a single empty can can be placed as it is in a suitable waste receptacle the question of disposing of numbers of waste cans can raise problems in view of the space required. Typically an empty can occupies a volume comparable with that it occupied when it is full. To provide for effective disposal there is thus a need to reduce the volume occupied by a waste can. To reduce the volume of an empty can it is necessary to apply a force acting to overcome the designed tendency of the can to resist deformation. Such a force can be applied by mechanical means. However such means are not necessarily conveniently available in locations where disposal is required, that is to say where a can is emptied, nor are such means necessarily desirably, or readily, operated by an uninformed user.

It is thus desirable that the can, once finished with, is collapsible so that it takes up the minimum volume possible when disposed of.

Collapsible containers are known and are normally collapsed by applying an axial force. US 5,209,372 describes a collapsible container in which an axial or rotational force may be applied to achieve collapsing. The container of US 5,209,372 has a sidewall consisting of a plurality of raised spiral ridges, defining therebetween a groove, which ridges extend from top to bottom of the container. At the bottom of the groove is a fold line.

When an appropriate force is applied, the spiral ridges collapse, somewhat in the manner of a bellows, resulting in a reduction in the longitudinal dimension of the container.

The present invention presents an improved design which does not rely on a bellows-like formation on the exterior of the container. More generally, the invention seeks to provide a container, and a method of disposing of such a container, without a need for any external equipment and without the need for application of excessive force.

According to a first aspect of the present invention there is provided a container comprising a cylindrical body with a longitudinal axis and closures at either end of the body, said container being characterised by a plurality of paths on the surface of the cylindrical body, each path being incline, at least over a part of its length, to the longitudinal axis, and each path defining along its length a locally weakened region of the cylindrical body.

Said paths may be formed on the outer surface of the cylindrical body, or on the inner surface of the cylindrical body. Alternatively, some of said paths may be formed on said inner surface, and some on the outer surface. In the latter case, the ends of respective paths on the inner and outer surfaces may cross or join, leaving just the thickness of the material of the cylindrical body between them, to thereby effectively form a line of weakness alternating from an"inner"path to an"outer"path in a zig-zag pattern right around the circumference of the container.

Each path extends generally in the direction of the longitudinal axis but need not necessarily be incline to the axis over the whole of its length.

For example, the ends of each path may extend parallel to the longitudinal axis, with the intermediate portion being incline as aforesaid. That part of the path which is incline, or the whole path if it is incline for its full length, may be straight or curved or any other shape, for example, helical.

Usually, all of the paths will be of the same form and have substantially the same angle with respect to the longitudinal axis; however, this is not necessary the case-for example, where paths are provided on both of the inner and outer surfaces, those on the inner surface may be at a different angle to those on the outer.

The paths may be formed by continuous locally weakened regions, or by discontinuous locally weakened regions. In the case of a path formed of discontinuous weakened regions, the regions are spaced apart along the path by distances, not necessarily the same, which are sufficiently small that the regions act together during collapsing of the container.

In an embodiment of the invention the paths are formed into a plurality of sets of paths spaced apart along the longitudinal axis. This technique has been found to enable long containers to be collapsed; otherwise the maximum practical limit of container length is approximately in the range of 1 to 1.25 times the container diameter. By this means, any length or size of container can be collapsed by utilising an appropriate repeating number of sets of paths. Conveniently, each such set has the same pattern of paths, but this is not essential. The patterns of each set may be circumferentially shifted with respect to one another for ease of operation. The patterns may also be controlled so as to produce pop-up recovery for amusement purposes.

Each such set of paths comprises a pattern of paths of the type described above, and preferably extends circumferentially completely around the container.

The container may be made from any suitable material, such as aluminium, steel, plastics material, paper or cardboard. An example of a container suitable for the application of the present invention is the well- known beverage can commonly used for soft drinks and beer.

According to a first preferred version of the first aspect of the present invention at least one of the paths comprises a continuous groove formed on the inside and/or outside surface of the cylindrical body, which groove thus locally thins the material of the body to provide the locally weakened region of the body. In an alternative embodiment, the groove does not actually thin the material of the body but locally folds the material so that it is stressed by its shape to be the point of first failure.

The grooves which comprise the paths may be formed in any convenient manner, for example by scoring or indenting of the material of the cylindrical body. In practice this might be achieved by, for example, press forming or drawing through dies. Paradoxically, the action of forming the grooves can actually enhance the strength of the container, potentially enabling thinner material to be used and resulting in a container which is cheaper to produce.

The grooves may have various cross section shapes and further work is being carried out to find the optimum shape. Currently it is felt that a very low radius"U"-section shape will be used.

Some care should be taken over the depth of the grooves: grooves which are too deep weakens the area resulting in splitting of the container when the container is collapsed; grooves which are too shallow may be aesthetically attractive, but can make the container difficult to collapse.

However, once collapsing has started, the process acquires a momentum which means that the grooves need not be as deep as is necessary to start the collapsing process in the first place. Thus the depth of the grooves can be graduated, longitudinally of the paths, to even out the collapsing force required, or a particular length of the grooves can be made deeper than the rest to overcome the momentum needed at the beginning of the collapsing process, and thus enable the process to get started. As an

alternative, it has been found that pressure on a particular area of the cylindrical body at the same time as the initial twisting action is undertaken to collapse the container will enable the collapsing process to start readily without excessive twisting force. This pressure may, for example, be applied with the thumb while at the same time the end of the container is held between the palms of the hands for applying the twisting force. An alternative trigger to collapse the can may be provided by varying the depths of the grooves forming the different paths around the can: for example, if one or more of the paths comprise grooves which are deeper than the remainder, then these deeper grooves will get the collapsing process started.

The angle at which the paths are incline will depend upon the circumstances. For cylindrical drinks cans, for example, the range of angles will be 13° to 16° to the vertical axis of the can depending upon the size of the can, and the number of paths. For a medium sized drinks can a typical angle might be 14.5°, with nine segments.

According to a second preferred version of the first aspect of the present invention at least one path comprises a discontinuous series of grooves or recesses, each groove or recess serving to provide in the path a sequence of locally weakened areas which together form the locally weakened region of the body.

In an embodiment of the present invention the container is filled with a material which is liquid or gaseous or a combination of a liquid and gaseous material.

As already mentioned, a primary intended use of the invention is to enable used cans to be collapsed and thus disposed of more efficiently.

However, in certain circumstances, it may be possible to collapse the can before use to thus save on storage and transport costs by reduced goods volume. In order for this to be successful, it must of course be possible to re-form the can back to its non-collapsed condition, for example by inflation, prior to filling. Only can materials which are susceptible to this

treatment will be suitable and it is currently felt that only cans made of plastics materials will be satisfactory.

According to a second aspect of the present invention there is provided a method of collapsing containers of the type according to the first aspect, said method comprising the step of: applying a torque to the cylindrical body about the longitudinal axis causing the locally weakened regions to distort, resulting in a reduction in overall length along the longitudinal axis.

The torque may be applied in any convenient manner, for example by holding the container by its ends and then rotating the ends in opposite directions. The resultant opposing twisting motion causes the container to fol long the paths and collapse inwards on itself.

In an embodiment, the step of applying the torque is preceded or accompanied by applying pressure to the exterior surface of the cylindrical body at an area adjacent one of the paths, in order to initiate the process which leads to the collapse. Preferably the application of pressure occurs simultaneously with the initial application of torque, to get the process started; once collapsing has started, the process acquires a momentum of its own, and the pressure can be released. This pressure may, for example, be applied by the thumb at the same time as the remainder of the hand grips the end for applying the rotating motion.

In order that the invention may be better understood, several embodiments thereof will now be described by way of example only and with reference to the accompanying drawings in which:- Figure 1 is a perspective view of a first embodiment of a container according to the invention, in its normal working configuration; Figure 2 is a view of the container of Figure 1 in its collapsed condition; Figure 3 is a side view of a second embodiment of a container according to the invention, in its normal working configuration; Figure 4 is a view similar to that of Figure 3, but showing the container in a partially collapsed condition;

Figure 5 is a side view showing the container of Figure 3 in a fully collapsed condition; Figure 6 is a side view of a third embodiment of a container according to the invention, in its normal working configuration; Figure 7 is a view similar to that of Figure 6, but showing the container in a partially collapsed condition; and Figure 8 is a side view showing the container of Figure 6 in a fully collapsed condition.

Figure 1 shows a container in the form of a beverage can 11 containing an aerated drink. The can 11 is made up of a cylindrical body section 12 with a longitudinal axis L, and a respective closure member at each of the top end 10 and bottom end 14. The top closure member includes a conventional tear out tab 15. The can 11 is made of aluminium alloy sheet. The can 11 can have printing on it, or have a separate sleeve surrounding it, bearing advertising and other information in a known manner.

The can 11 has on its body section 12 a plurality of paths (paths 13A to 13H being visible-corresponding paths are also formed on the opposite, unseen, side of the can 11) in the surface of the body section 12, each path following a helical or otherwise curved track about the longitudinal axis L. In this case each path 13A to 13H is formed by an indented groove which serves to reduce the wall thickness of the wall of the body section 12 so as to define along the length of each path 13A to 13H a locally weakened region of the body section 12. The paths 13A to 13H have lying between them strips, typically strip S, of uniform thickness layers of the body material. In the working form shown in Figure 1 the can 11 has a normal working length W.

To drink the contents of the can 11 the tab 15 is raised and the contents drunk from, or poured out by way of, the aperture resulting from the opening of the tab. Once emptied the can 11 needs to be disposed of.

To do this, the can 11 is grasped in one hand at or near the top end 10 and in the other hand at or near the bottom end 14. The top and bottom ends

are then twisted in opposite directions to apply a torque to the body section 12 about the axis L. As a result of the torque, the lines of reduced wall thickness corresponding to the grooves forming the paths 13A to 13H fail, and the intermediate strips corresponding to strip S are twisted up to form a series of overlapping and contracted strips as the can 11 is screwed up into the form of collapsed can 11', shown in Figure 2. In that form, with an overall compressed length D, the can 11'is about one quarter the normal working length W. The contracted can 11'shown in Figure 2 can then be disposed of in a conventional waste bin. By disposing of the can in this way it is possible to provide for much more compact storage of such cans when used in a given waste bin. As a result the overall density of the material in the waste bin is higher and the individual cans more closely disposed than has heretofore been possible. This provides for advantages further down the waste disposal route since the contracted cans are readily packed in larger numbers into a baling machine to enable the waste material to be compressed into a bail for recycling.

The direction of twisting to collapse the can is such that the top end 10 of the can is twisted anticlockwise with respect to the bottom end 14 of the can. The same effect may be achieved by holding the top end 10 of the can and twisting the bottom end 14 in the clockwise direction. An opposite direction of twisting-i. e. such that the top end 10 of the can is twisted clockwise with respect to the bottom end 14 is possible, but only if the paths 13A to 13H are incline in the opposite direction with respect to the axis L.

The grooves are formed by machining, scoring or otherwise indenting the exterior and interior surfaces of the material of the cylindrical body section 12 to thereby form lines of weakness. It has been found that the existence of the grooves actually strengthens the can in compression, opening up the possibility that a thinner can material may be used, whilst at the same time allowing the can to collapse upon applying the aforesaid torque.

Figures 3 to 5 show a second embodiment of the invention, also a beverage can. Referring to Figure 3, it will be seen that, as well as the paths 13A to 13E formed in the exterior surface of the body section 12 of the can, there is a further set of paths 16A to 16F, shown dotted, formed on the inside surface of the can. In the embodiment illustrated, each exterior path 13 is joined top and bottom to the next adjacent interior path 16- thus, for example, exterior path 13B is joined at the top to interior path 16C and at the bottom to interior path 16B. Although shown as being straight on the drawings, the paths 13,16 are actually straight only in the two dimensional blank which would be formed if the material of the cylindrical body section 12 were laid out flat. Thus, when the body section 12 is formed into a cylindrical shape, the paths would actually take on a curved appearance when seen in elevation, as in Figure 3.

In order to form the grooves which comprise the paths 13,16 in the can shown in Figure 3, the surface of the can is scored or otherwise indented, as before. The difference is that, in the case of the can of Figure 3, the scoring or indenting takes place from the exterior side of the can material in the case of paths 13 and from the interior side in the case of the paths 16.

Twisting of the ends of the can in the manner described above causes the can to collapse longitudinally. Figure 4 shows the can partially collapsed and Figure 5 shows the can when fully collapsed. The can is fully collapsed when the top and bottom of the can meet and lock together.

Due to physical constraints, it has been found that there is a maximum height of container which can be collapsed using the formation of paths illustrated in the above-described embodiments. Realistically, the maximum length of container which can be collapsed by these techniques is probably approximately in the range of 1 to 1.25 diameters. Figures 6 to 8 show a third embodiment of the invention for use with a taller container.

In this case two sets of paths of the type illustrated for the container of Figures 3 to 5 are provided. In addition to the upper set, given the same reference numerals as previous: 13A etc., and 16A etc., there is a lower

set of paths comprising paths 17A to 17F formed on the exterior surface of the body section 12 and paths 18A to 18F, shown dotted, formed on the interior surface. Other detail is the same as in the embodiment of Figures 3 to 5, described above.

The two sets of paths are separated by a short groove-free axial space 19 and a similar short groove-free space 20,21 is left at the top and bottom ends respectively, as with the previous embodiments. In addition, the pattern of paths in each set are offset in the circumferential direction with respect to one another, as is made clear in Figure 6.

Twisting of the container of Figure 6 causes the container to collapse longitudinally, as described above, but this time the collapse takes place in two sections, corresponding to the two sets of paths, as clearly illustrated in Figure 7. Figure 8 shows the container in the fully collapsed condition.