IE980947A1 - Flexible Collapsible Container - Google Patents

Abstract

A container (1) with a flexible body (2) which is collapsible and erectable, the body having a base (3) and side walls (4). Elongate stiffening means (5) stiffen the flexible body (2). The base (3) is a sheet (22) of flexible material attached to the side walls (4) and having an area inside the attachment substantially equal to the cross-sectional area of the erected container so that the base sheet (22) is taut. An inner sheet (8) of flexible material extends across the interior of the container above the base (3). The inner sheet (8) is attached to the side walls (4) and/or the stiffening means (5) at a position spaced above the lower end of the stiffening means, and having an area inside the attachment greater than that of the base so that the inner sheet is slack. The inner sheet (8) accommodates and takes up the shape of a liner (41) filled with a fluid material and does not transmit this shape to the base of the container. The container is thus more stable. The container may have a octagonal cross-section and is cylindrical in shape when filled. <Figure 2>

Description

FLEXIBLE COLLAPSIBLE CONTAINER Technical Field The invention relates lo a collapsibIc*W?5f5TBST'c(!ih.sTruere3'’o'mexible material, particularly to a collapsible container suitable for sloring/transporting flowable materials such as liquids.

It is often necessary or desirable to store or transport liquids. Steel drums or other rigid containers are conventionally used for this purpose. Steel drums are very widespread in use and are not collapsible. Containers for liquids should be strong enough to provide for maintenance of the physical integrity of the container, thereby obviating spillage and waste, but at the same time it is often necessary for a container to be transported empty. Transporting of empty containers is wasteful space, and is thus costly. Collapsible containers are used so that the containers when empty can be transported in a much more compact and cost effective way. Collapsible containers are difficult to stack and handle generally when filled with a liquid. This is due at least in part to the tendency of the liquid to cause the bottom of the flexible bag to balloon or bulge distorting the shape of the entire base of the container. This creates problems with transporting, stacking and other handling problems.

As far as the present inventor is aware there has never been contemplated or provided a collapsible container which is substantially drum-shaped when erected/filled. The term drum-shaped is used herein to refer lo a container with substantially cylindrical walls (e.g. of a polygonal cross-section with n sides. Suitably n is an even number. To allow ease of folding of the container n is suitably 6. Preferably n is 8) and a substantially flat base. It is an object of this invention to provide a collapsible liquid container with relatively large internal volume which overcomes the problems of known containers in particular with respect to the retention of the shape of the container and which is preferably generally drum-shaped in its erected/filled configuration.

Background Art European patent no. 0 360 730 describes a flexible semi-bulk container that is suitable for use with fluidized solids, semi-solids, slurries and liquids and for shipping in less than truckload shipments where the package should have adequate stability to stand alone. The container described is square or rectangular in its erected configuration. Rigid panels provide the necessary stability to allow the container to stand alone. In one embodiment the rigid panels form a four-sided sleeve. The problem of overcoming the tendency of the container described to take up the shape of its contents is not discussed. No drum-shaped container is contemplated.

WO 97/20758 describes a container for storage or transport of liquids which has a flexible body which is collapsible and erectable. The body has a base and side walls with pockets therein. Stiffening members are provided in the pockets to stiffen the flexible body. The container is generally rectangular or square-shaped in its erected configuration. A transverse gusset is provided at each corner between adjacent side walls, and a reinforcer extends from the corner to the gusset - an arrangement which allows stackability as a result of better retention of shape of the container due lo its construction. While the construction achieves retention of shape of the side walls the problem of bulging in the base of the container is not discussed.

Other forms/methods of packaging are described in US 4,622,693 and US 3,896,991. EP 0,401,934 A describes a generally rectangular or square-shaped package for storing and transporting bulk goods. The package has an inner and outer frame which are partially attached to each other. EP 0,552,845 A describes a generally rectangular or square-shaped container having a relatively stiff form-retaining supporting irame and a flexible shell member. The supporting frame is necessary for retention of shape of the container.

EP 0,475,703 A describes a bulk container of flexible fabric having a substantially rectangular base and tour walls with four bridging panels extending between walls across the corners at the junctions of the walls. The bridging panel is integral with the wall. While the bridging panel goes some way Inward aiding retention of shape of the side walls the problem of bulging in the base of the container is not discussed.

DE 2,417,109 A describes a tank formed from a bag-shaped flexible material for bulk goods, particularly flour, with a rigid conical outlet end. The tank walls have overlapping folds which are connected each to the next. Uprights may be placed in the tank walls for stability. While the walls of the lank are flexible and collapsible the conical outlet is not.

While most of these prior art documents do provide flexible collapsible containers none provide a collapsible container which is drum-shaped when in its erected configuration. It is also desirable lo provide such a container which retains its shape on being filled. The shape of the base of the container in particular should be as planar as possible to allow stability in transporting, handling etc.. This is particularly the case where the content is to be a fluidized material, a liquid or indeed any flowable material.

Disclosure of Invention In particular it is an object of the invention to provide a container which retains its desired shape on filling and in particular lo provide a container which ameliorates the problem of bulging/ballooning of the base of the container on filling. It is particularly desirable lo provide a drum-shaped collapsible container which achieves this objective and which is suitable for storing or transporting fluidized material in bulk and which is also collapsible to a storable or folded configuration yet which can stand alone. In particular it is desirable that the container should not require the aid of an external stand or prop while being filled and the containers should be transportable for example when standing on a pallet without the contents of the container causing an upset or instability of the container.

According to the invention there is provided a container comprising a flexible body which is collapsible and erectable, said body having a base and side walls, and elongate stiffening means having upper and lower ends to stiffen the flexible body, the lower end of the stiffening means being disposed proximate the base, the base comprising a sheet of flexible material attached to the side walls and having an area inside the attachment substantially equal to the cross-sectional area of the erected container so that the base sheet is taut, the container further comprising an inner sheet of flexible material extending across the interior of the container above the base, the inner sheet being attached to the side walls and/or the stiffening means at a position 1() spaced above the lower end of the stiffening means, and having an area inside its attachment greater than that of the base so that the inner sheet is slack.

The provision of the flexible inner sheet in this manner provides a number of advantages: it takes up some of the loading placed on the container by the contents and transmits the loading into vertical loading on the stiffening means (and the body). This reduces the horizontal forces exerted against the side walls of the container by its contents thus helping to relieve bulging and other out-of-shape distortions of the container. Secondly it alleviates the problem of the contents (in particular liquids) causing the base of the container to bulge downwardly. The present inventor has found that without the flexible inner sheet the ballooning of the base gives the sides of the container the appearance of moving upwards so that the contents extend lower in the container than the side walls. This gives the container an unstable base and causes problems with handling/storage. If this happens the ability of the stiffening means to stabilise the container is reduced and may be totally lost. Deformation of the flexible inner sheet internally is not reflected in the outward shape of the container.

In a preferred arrangement the container body is constructed to adopt a substantially cylindrical shape when pressured by contents placed in it. In this embodiment suitably the stiffening means is resiliently deformable about vertical axes so as to take up the cylindrical shape also. The provision of the resiliently deformable .stiffening means allows the side walls of the container to conform to a cylindrical shape.

The taut base sheet (which suitably is constructed of heavy duly plastics material) can take up loading not taken up by the first sheet. This arrangement gives the container a substantially planar base when in a standing position.

In a desirable construction the stiffening means has al its lower end an end portion pivotable about a horizontal axis relative to the stiffening members. In this embodiment, pressure downwardly along the elongate axis of the stiffening members causes the end portion to pivot inwards in the direction of the underside of the container. This arrangement allows for greater stability of the container in its filled or partially filled configuration as extra surface area of the stiffening members is in contact with the ground. In a further embodiment the end portion has a ground pivot axis or line of weakness so that the end portion folds in concertina fashion under loading.

In one preferred arrangement the side walls comprise pockets into each of which are insertable individual stiffening members, each of the stiffening members (which together form stiffening means) having an end portion pivotable relative to its respective stiffening member so that a segmented rim is formed by the series of end portions in their pivoted configuration.

In a more preferred embodiment the container has a body of flexible material such as that used hitherto for flexible intermediate bulk containers, e.g. a fabric such as woven polypropylene which is stitchable or a material which is weldable. The word join is used herein to include in particular adhesion, stitching or welding but is not limited to these methods. The term joint line covers either a line along which a joining is made by adhesion, a stitch line or a weld line.

In a prelerred construction the container has a liner therein, particularly a liquid impermeable liner e.g. of eo-extruded plastic film such as polyethylene, conforming to the interior configuration of the body. A container may for example have an octagonal cross-section.

In the preferred embodiment (which in itself is inventive) the side walls comprise a series of closely arranged pockets formed by two of a series of lateral joint lines, each lateral joint line forming one side of consecutive pockets, each pocket having a stiffening member inserted therein, the stiffening member being a tight fit in each pocket so that the folding the container stretches the container body so that the container is biased toward its erected configuration. This effect creates a container which is stable in its erected configuration and which moves at least partly toward its erected configuration under the bias provided by the strained folded container body. If the conformation of the pockets and stiffening members is tight enough the body will be held firmly in its fully expanded erected configuration.

In the most preferred embodiment stiffening members are received in all of the pockets and more preferably the pockets are closed by joining of the material defining the pockets at the top and bottom thereof.

The stiffening means may each comprise a planar stiffening member of resiliently deformable material such as a plastics or ply-board member. It has been..... surprisingly discovered by the present inventor that the use of a corrugated plastics material is particularly useful as this material takes up the cylindrical shape of the container well, and it also has sufficient strength to withstand the pressures of the container, particularly those transmitted by the first flexible sheet described above. The stiffening members are also relatively inexpensive to make and use.

Brief Description of Drawings A container embodying the invention is hereinafter described by way of example, with reference to the accompanying drawings.

Figure 1 is a perspective view of a container of the invention in an erect condition with a flexible closure for the container folded into the container (some internal features shown in dashed outline); Figure 2 is a perspective view (part sectional)of the container of Figure 1 with the flexible closure removed and showing the means to stiffen the body inserted within pockets formed in the body; Figure 3 is a sectional view through the bottom portion of the container illustrated in Figure 1; Figure 3A is a sectional view of one desirable construction of a container, the stiffening means having a lower end portion pivotable about a horizontal axis relative to the stiffening means; Figure 4 is a sectional view through the upper portion of the container illustrated in Figure 1; Figure 5 is a perspective view of the container of Figure 1 with the flexible closure for the container withdrawn from the container'and opened upwardly for filling of the container; Figure 6 is a perspective view of a container of Figure 1 the flexible closure for the container being drawn together and tied in a closed position; Figure 7 is a cross sectional view of an alternative construction of the container of Figure 3A; Figure 8 is a perspective view of the container of Figure 1 in a collapsed or folded configuration.

Modes for Carrying out the Invention Referring to the drawings, there is shown a container 1, comprising a flexible body 2 of constructed of a flexible fabric which is collapsible and erectable. The body 2 has a base 3 and side walls 4 composed (in the embodiment illustrated) of eight similar wall portions. Elongate stiffening members 5 each having an upper end 6 and a lower end 7 stitlen the flexible body 2. The lower end 7 of each of the stiffening members 5 is disposed proximate the base 3 while the stiffening members extend upwardly along the container 1 so that the upper ends 6 of each are located near lo the top ol the container 1.

The container 1 has a flexible base sheet 22 of heavy duty material which extends across the container to form the base 3 of the container. The base sheet 22 is arranged between the side walls 4 so as lo be taut in the erect configuration of the container. The base sheet 22 is stitched on a stitch line 50 to the bottom fold 24 of the side wall material. The base sheet has an area substantially equivalent to that of a horizontal cross-sectional area of the erected container. The taut case sheet can take up loading not taken up by the flexible inner sheet 8 described below. The sheet 22 may be a double layer sheet.

As can be seen from Figures 2 and 3 in particular, the container 1 further comprises an inner sheet of flexible material 8 extending across the interior of the container 1 above the base sheet 22. The sheet 8 is attached to the side walls by stitching 10 which passes through a line of perforations in the stiffening members 5 about 2-3 cm above the lower edge thereof. The stitch line 10 extends about the internal circumference/perimeter of the container. The sheet 8 is retained in a desired position by the side walls 4 and/or the stiffening members 5 at a position spaced above the lower ends 7 of the stiffening members 5. The sheet 8 has an area inside the stitching 10 which is greater than the horizontal cross-sectional area of the erected container 1 so that il is held in a slack or unlensioned mode as is most clearly shown in Figure 3. The sheet 8 is arranged to transmit at least part of a load placed on il into a loading along an elongate axis of the stiffening members 5 as will be hereinafter described.

The side walls 4 are formed in two halves labelled 11 and 12. The two halves 11, 12 are joined by two heavily stitched seams 13,14. Each seam 13,14 acts as a joint line about which the body 2 can be folded. Attached to the container 1 are a pair of lifting straps 15. The lifting straps 15 can be used to raise the container (when filled) using for example a fork lift truck.

The container 1 is provided with a flexible closure 16 which in the configuration of Figure 1 is turned down into the container 1. The flexible closure 16 is shorter than the height of the container so that when its upper end 17 is folded into the container it extends about three quarters of the way toward the base 3. In this folded-in configuration the flexible closure 16 is held within the container when the container is in its collapsed configuration (see Figure 8). The flexible closure 16 has a lie 18 attached to it which can be used to tie the flexible closure closed when the container is filled. To fill the container 1 the flexible closure 16 is withdrawn from its folded position within the container as shown in Figure 5. For filling, a liner (not shown), will be used, particularly a liquid impermeable liner e.g. of co-extruded plastic film such as polyethylene, conforming to the interior configuration of the body. The container is filled in the direction of the arrow. After filling the upper end 17 of the flexible closure 16 is drawn together and tied tightly using the tie 18 as shown in Figure 6. As shown in Figure 4 in particular, the flexible closure 16 is stitched to the inside of the top of the container al a stitch line 23. The stitch line 23 also closes the upper ends of pockets 20 in the side walls 4.

In the embodiment, the body 2 is made from flat or circular woven polypropylene or any other suitable material. The polypropylene is stitched to form the octagonal-in-plan shape shown. The side walls 4 have formed therein a series of closely arranged pockets 20, in the embodiment eight equally sized pockets. These pockets 20 are formed from single or double layers of polypropylene fabric, stitched together. As shown the pockets 20 are formed by a series of vertical joint lines 21 which in the embodiment are stitch lines. The seams 13,14 also act as joint lines even though these seams are more heavily stitched than the other joint lines. Each pocket 20 is formed by two of the series of vertical joint lines 21, so that as shown each vertical joint line 21 forms one side of consecutive pockets. Each pocket 20 has a stiffening member 5 inserted therein. The stiffening member 5 is a tight fit in each pocket so that folding the container about the joint lines stretches the material of the container body so that the container is biased toward its erected (unfolded) configuration. The container 1 when unfolded fully tends to snap into shape in a locked open conformation. Each stiffening member 5 is shown in dashed outline in Figures 1 and 2.

The filling of the container 1 is as follows. As described above the flexible closure 16 is moved to the position of Figure 5. A liner (not shown) is inserted (if necessary) and filling is commenced. The filling operation is described for ease of reference as filling with a liquid. The liquid is filled into the liner. The liner being flexible conforms to the shape of the liquid and moves with the liquid to fill the internal volume of the container. The pressure of the liquid firstly begins to exert a downward force on the flexible inner sheet 8 which bears at least some of the weight of the liquid. The flexible inner sheet 8 being partly slack tensions with increasing weight of liquid. This tension is transmitted as described above to the stiffening members 5 forcing them in a downward direction illustrated by the arrows shown in Figure 3. Folds of material 24,25 respectively resulting from closure of the lower end of the pockets 20 and the provision of the base sheet 22, are pressed downwardly until the weight of the liquid forces the stiffening members 5 to sit firmly on the ground. The stiffening members 5 are separated from the ground only by a layer of material forming the pockets 20. In this construction there is a spacing between the inner sheet 8 and the base sheet 22 so that the inner sheet 8 can deform to accommodate at least part of the shape taken up by the liquid. The embodiment described above is suitable for contents such as fine powders and viscous liquids.

With reference to Figure 3A a preferred embodiment of the present invention will be described. The container 1 is filled as described above with a liquid 40 held in a plastics liner 41. In the embodiment of Figure 3A each of the stiffening members 5 have at their lower ends an end portion pivotable relative to the stiffening members.

The pivotable portion 30 can be provided by scoring, perforating or otherwise creating a fold line or pivot transverse to an elongate axis of each stiffening member 5.

However in a particularly simple construction the line of perforations in the members 5 to accommodate the stitching 10 can be used as the pivot or folding line 42 as shown in Figure 3A. In an alternative embodiment the flexible sheet 8 may be attached to the walls ol the container above the pivot point 42. Pressure downwardly along the elongate axis of the stiffening members (such as is caused by the loading on the flexible sheet 8) causes the end portion 30 to pivot inwardly in the direction of the underside of the container. This provides a segmented rim 31 about the base of the container. A single pivotable portion 30 on each stiffening member 5 is sufficient to impart increased stability lo the container 1. In the preferred arrangement shown the segmented rim is formed in the space between the taut base sheet 22 and the flexible inner sheet 8. If the pressure of liquid is sufficient then the liner containing the liquid may force the flexible inner sheet 8 downwardly until part of the load rests on the rim 31. The inner sheet 8 supporting the liquid has a “footprint” on the base with a diameter less than that of the base.

An even more stable arrangement is shown in Figure 7 where the end portion 30 is designed to assume a v-shape on filling the drum. In the embodiment of Figure 7 the container is filled with a liquid 40 held in a liner 41. The desired folding can be achieved by providing for example two score lines on opposite sides of the stiffening members 5. The v-shaped arrangement is shown in Figure 7, the stiffener 5 having a second pivotable portion 32 which pivots in a direction outwardly from the container. Alternatively and as shown in Figure 7 an upper fold (or crease) line may be formed by a line of perforations used for stitching the flexible sheet 8. In this arrangement the lower fold line 45 is mechanically weaker than the upper fold lines 46 so that the lower fold line 45 is the first to give under the pressure of the contents. If the direction of pivoting about the lower fold line 45 is predetermined (for example by scoring on one side) the pivotal force created can be used to urge pivoting about the upper stitch line in the required direction. The end portion thus folds in concertina fashion under this loading. This control of pivoting allows the v-shaped arrangement to be formed. The increased surface area of the stiffeners 5 providing vertical support for the container gives the container more stability. The containers described in Figures 3A and 7 are suitable tor holding contents such as flowable powders or non-viscous liquids.

An empty container 1 can be folded (collapsed) as shown in Figure 8. The container 1 is emptied if not already empty. The container may be folded with the liner in place. The flexible closure 16 is for the sake of neat packing of the container folded into the container (to the position shown in Figures 1,3 and 4). The container is then folded about its hinge lines so that the heavy duty seams 13,14 move to the centre of the folded arrangement. The folded container 1 is then substantially flat in configuration having a width corresponding to the width of two pockets 20. The straps 15 are also held neatly within the folded structure.

In order to collapse the container, it i.s only necessary to fold the body 2, inwardly al the stitch lines 13 and 14, thereby enabling a Hal collapsed or stowed container to be achieved, with the stiffening members 5 in place, the stitch lines providing hinge lines. The flexible sheet 22 and inner sheet 8 can be folded neatly while the folded container.

The user has merely to open the container to the shape shown in Figure 1 by pulling out the two opposite sides about hinge lines 13, 14, inserting a liner if necessary, and commencing filling of liquid thereinto, The container can be placed on a pallet, after opening out. The rigidity of the stiffening members and the flexibility of the fabric ensures ready movement between the collapsed and erected conditions, the stitching and stiffening members ensuring that the unfilled yet erected container maintains its rigid shape prior to filling. The substantially octagonal cross-section of the erect container is pressured into a substantially circular cross-section on filling with contents (such as liquids or fluidized material) which apply pressure evenly about the internal perimeter of the container.

The side walls 4, may be formed of one or two pieces of flexible material folded so as to provide double walls. The base sheet may also be formed of a separate piece of material. Each pocket 20 may however be constructed independently. The pieces of material are then joined. A variety of closures could be used with the container of the invention The liner may be a polyethylene liner. Glands for filling and/or emptying the container could also be provided. The glands could be secured to apertures in the top or tront. To ensure that the liner takes up, and conforms to, the interior configuration of the container body, the liner, after insertion and connection of the glands, is inflated, then deflated suitably by collapsing the container 1 to the collapsed, flat shape. The liner thus conforms to the body shape of the container 1 in its erect mode and takes up the substantially octagonal configuration of the interior volume of the container.

It will be understood that where the material of the body is fusible, the stitching may be replaced by welding, for example heat and pressure welding or ultrasonic welding, to form hinge lines as before. An aperture may be provided in a side wall for a discharge outlet. A planar member may be removably inserted in the 1() base 22 to strengthen the container.

The stiffeners can be made of any suitable material, though it is particularly desirable that they are constructed of resiliently deformable material such as a plastics material. It has been discovered that corrugated plastics material is particularly useful in this respect. One example of such material is corrugated polypropylene. The stiffening means may alternatively be a unitary piece for example a cylindrical (or polygonal e.g. octagonal) sleeve. This type of stiffening means would have a suitable number of fold lines to allow the container to collapse about a longitudinal axis. For example the sleeve could be scored.

In one construction the container has the following dimensions : Length of each pocket approx. 90 cm Width of each pocket approx. 23 cm Diameter of erected container 60 cm Typical capacities of the container of the present invention are 205, 215, 225 and 1,000 litres, though it will be appreciated that any desired volume can be achieved.

Claims (7)

1. A container comprising: a flexible body which is collapsible and ercctable, said body having a base and side walls, and elongate .stiffening means having upper and lower ends, to stiffen the flexible body, the lower end of the stiffening means being disposed proximate the base, the base comprising a sheet of flexible material attached to the side walls and having an area inside the attachment substantially equal to the cross-sectional area of the erected container so that the base sheet is taut, the container further comprising an inner sheet of flexible material extending across the interior of the container above the base, the inner sheet being attached to the side walls and/or the stiffening means at a position spaced above the lower end of the stiffening means, and having an area inside the attachment greater than that of the base so that the inner sheet is slack.

2. A container according to claim 1 wherein the container body is constructed to adopt a substantially cylindrical shape when pressured by contents placed in it.

3. A container according to claim 1 or claim 2 wherein the stiffening means has at its lower end an end portion pivotable about a horizontal axis relative to the stiffening members.

4. A container according to any preceding claim wherein the side walls comprise pockets into each of which are insertable individual stiffening members, each of the stiffening members having an end portion pivotable relative to its respective stiffening member.

5. A container according to claim 4 wherein the side walls comprise a series of closely arranged pockets formed by two of a series of lateral joint lines, each lateral joint line forming one side of consecutive pockets, each pocket having a stiffening member inserted therein, the stiffening member being a light fit in each pocket so that on folding (he container body stretches so that the container is biased toward its erected configuration.

6. A container according to any preceding claim wherein the end portion has a ground pivot axis or line of weakness so that the end portion folds in concertina fashion 5 under loading.

7. A container according to any preceding claim wherein stiffening members are received in all of the pockets and more preferably the pockets are closed by joining of the material defining the pockets at the top and bottom thereof. S. A container according to any preceding claim wherein the stiffening means is a corrugated plastics material.