EP0571458B1

EP0571458B1 - Flexible containers

Info

Publication number: EP0571458B1
Application number: EP92904596A
Authority: EP
Inventors: Jeffrey Robin Caldwell-Nichols
Original assignee: AgriTay (Holdings) Ltd; AGRITAY HOLDINGS Ltd
Current assignee: AgriTay (Holdings) Ltd
Priority date: 1991-02-22
Filing date: 1992-02-19
Publication date: 1996-05-01
Anticipated expiration: 2012-02-19
Also published as: EP0571458A1; WO1992014659A1

Abstract

A flexible intermediate bulk container is produced by cuts (29) down from a top edge of a tubular base panel to provide opposing portions (30), which are then joined at their top edges to form a lifting loop (31), and opposing flaps (40) which are extensible below the loop (31) to provide a substantially flat, secure top closure to the filled container. The resultant container has a well defined aperture for lifting purposes and, when filled and stored out in the open, good stability in high winds. The flaps (40) may be secured prior to or subsequent to filling of the container.

Description

TECHNICAL FIELD

This invention relates to large capacity flexible containers which are suitable for storage and transport of various goods, particularly dry goods of powdered or granular type.
Such containers are often referred to as flexible intermediate bulk containers and they typically have a capacity in the range from 0.25 - 2.0m³ and are rated as safe for loads of half a tonne up to three tonnes. They are made of flexible material which must be of adequate strength for lifting of the filled containers by engaging one or more handles or loops at the top. The usual material is woven synthetic plastics, for example woven tapes of polypropylene.

BACKGROUND ART

One conventional method is to manufacture containers of this type with a single integral lifting loop or handle at the top for engagement by a fork lift mechanism or hook. For example, EP-A-0118112 discloses a container of this type produced from a body of tubular woven material or from a body of flat woven material which is seamed at the sides. Slits are provided by cuts down from the top edge of the material or by unseamed edge regions above a load carrying section of the container. Top edge regions at respective sides of the cuts or slits are joined and the material above the load carrying section is gathered together, often within a sleeve, to provide an integral lifting loop or handle which includes substantially all the longitudinal fibres or tapes of the woven material. Manufacture of this style of container is simple and inexpensive and consequently it is widely used.
However, the above-described known style of container has certain disadvantages.
On such disadvantage is that the integrally formed lifting loop offers a restricted aperture therebelow as target area for engagement of lifting means, e.g. fork lift tines, because substantially all the longitudinal fibres or tapes of the body material extend into the lifting loop. In practice, fork lift operators have difficulty in accurately aiming for such restricted apertures. This is troublesome in itself and also frequently results in damage to the material of the loop. This can have serious safety implications since if damage to the loop significantly impairs the strength thereof subsequent lifting could be hazardous. Moreover, where such containers have been stacked, the lifting loops of lower containers are generally so collapsed that it is necessary for operatives manually to raise them to expose the aperture for lifting purposes. If this is not done, probing with the lifting means is likely to result in damage to the lifting loop and/or to an inner liner, if present.
A further problem arises when filled containers of this style are required to be stored out in the open for lengthy periods, exposed to all types of weather. Field studies and experiments in a wind tunnel have revealed that a lifting loop which includes substantially all the longitudinal fibres or tapes of the base material flaps so violently in high winds as to lead to disintegration, e.g. by fraying of edges. Even modest exposure to wind speeds which are commonly encountered in practical situations can impair lifting loop strength to such a degree as to make lifting unsafe. Furthermore, material of a liner to such a container, in which the contents are enclosed, is liable to damage by friction either as a result of the violent motion of the lifting loop, particularly if it is frayed or otherwise damaged, or as a result of its own motion where it is exposed and capable of billowing. If the liner is punctured or split it no longer provides an effective barrier to moisture and the contents are likely to be ruined. Thus, considerable economic losses can result from the susceptibility of these containers to wind damage.
GB 2042469 discloses a container in which upward extensions of only part of the walling are used to provide a lifting loop or handle. An upstanding spout is formed between these extensions by making V-shaped cut outs and seaming the edges thereof. This is not a viable method of producing a container. Such V-shaped seaming tends to suffer from high levels of stress at the base of the V causing localised fabric failure at relatively low loads. Furthermore, the spout has been shown in wind tunnel tests to flap violently, resulting in damage to the spout material and any liner within the container in the manner previously discussed.
GB 1581438 discloses a cuboid container in which only half the walling material can extend into the lifting area. This container is produced from at least two lengths of woven material by stitched seams at each join between side and end walls and also along bottom wall edges. This style of container is not economical to manufacture and is not widely used. It has two main limitations, namely inefficient use of fabric strength and the fact that the container inevitably takes up an oval cross section in use as a consequence of two of the four sides being unrestrained, particularly during lifting. Distortion to oval cross section leads to storage problems and stacking can be unsafe.

OBJECT OF THE INVENTION

An object of the present invention is to provide a method of manufacturing a flexible container with at least one integral lifting loop or handle as simply and as economically as possible, the resultant container requiring a minimum of intervention by operatives upon filling and lifting, and being more resistant than any hitherto known container designs to handle and/or liner damage upon lifting or upon exposure to high winds.

DISCLOSURE OF THE INVENTION

With this object in view, the present invention proposes a method of manufacturing a flexible container of the type having side walling of tubular form and at least one lifting loop which is an integral extension of the side walling, comprising the steps of cutting the side walling from the top edge thereof to provide at least two portions and at least two flaps in the upper regions of the side walling, and joining together the top edges of said portions to form the lifting loop or loops, characterised by slits in the side walling defining said portions and flaps, and by the steps of extending the flaps, which do not contribute to the loop or loops, across the top of the container below the lifting loop or loops, and securing them in position to provide a substantially laid flat closure to the top of the container.
By having only a proportion of the body material extending to form the lifting loop or loops and by leaving the material which does not contribute to the loop or loops as flaps which can be pulled tight across the top of the container below the loop or loops, a much wider aperture for engagement of lifting means can be obtained. At the same time, as the loop or loops are reduced in surface area, the tendency to flap under windy conditions is minimised and susceptibility to damage is reduced as a consequence. Use of the flaps to provide a top closure which is stretched as tightly as is practical further minimises any possibility of wind damage to a liner, as the latter is not free to billow and is not exposed to contact with the flapping loop or loops. This top closure also provides protection to a liner against damage during handling and storage of a filled container.
As is conventional, the side walling or body material of the container of the invention will generally consist of woven material having longitudinal and transversely extending interwoven strands. The term "strands" as used here should be understood to include tapes or fibres or any other filamentary elements. To achieve the desired enhancement of lifting aperture size, wind stability and physical top protection, whilst maintaining a uniform cross section and adequate handle strength, the lifting loop or loops should ideally include between 50% and 75% of the said longitudinal strands of the woven material. The optimum has been found to be between 60 and 65% allocated to the lifting loop or loops. The protective flaps will then include all, or a substantial proportion of, the remainder of the longitudinal strands, i.e. a small portion may be cut away altogether.
The portions of material forming the lifting loop or loops and the portions of material left as flaps need not be the same length in the finished container. Either could be cut shorter than the other, although it would be more usual for the flaps to be cut shorter than the portions forming the loop or loops.
The body material for production of containers in accordance with the invention consists of tubular walling. This may be formed by flat pieces joined by seams. Preferably, however, the body material is woven in one piece as a tube so as to avoid additional steps of seaming in the production process, which must be kept as cost effective as possible.
Within the scope of the invention, two main styles of container are proposed.
On the one hand the initial unfilled container may be supplied with loose flaps which will be secured across the top of the container only after the container has been filled. The flaps may then be secured by adhesive or by stitching or by use of tie tapes, which may be provided on one or both of the flaps, or by any combination of these. At the same time the flaps can be tensioned to maximise aperture size for lifting purposes and protection of any liner against wind damage. A tight top closure also secures the contents of the container so that a more compact and stable package results.
On the other hand, the initial unfilled container may be supplied with flaps already secured across the top of the load receiving section of the container. The flaps may be attached to each other directly, e.g. by stitching. Additionally or alternatively side edges, or at least portions of side edges, of the flaps may be connected to the base of the respective sides of the lifting loop or loops, e.g. by stitching. Another possibility is that the flaps are connected to each other indirectly by way of one or more intervening panels of stretchable material, such as elasticated or knitted material. A container with flaps already secured has the advantage that additional manipulation by operatives to secure the flaps after filling can be avoided.
In embodiments where the flaps are directly connected it is not possible to achieve such a tight top closure as with securement after filling, because of necessary allowance for variations in the exact volume of filling material and for settling of contents. Tension across the top closure may, in such cases, be promoted by making the combined length of the flaps, when joined, in extent across the container top, less than the diameter of the container by at least 20%. Additionally or alternatively it may be appropriate, with this style of container, to make provision for additional tensioning of one or both flaps, after filling, by tie tapes or similar. In embodiments where one or more stretchable panels are provided to connect the flaps, it should still be possible to achieve a reasonable degree of tautness across the container top, after filling, owing to the resilience of the said panel or panels.
With either style of container, i.e. with flaps closable after filling or closed prior to filling, it is advantageous for the flaps to overlap to provide double layer or multilayer protection. In this respect, one flap may simply overlie the other, or one or both flaps may be folded over. Most advantageously a double layer extends over the full width of the container. However, a double thickness across at least 20%, and preferably over 50% of the width of the container top, still has benefits. It has already been stated that the flaps may be attached directed to each other. In certain embodiments, distal side edge regions of the flaps may be secured to each other to provide a filling spout for the container. After filling, such a spout will be folded down flat and secured across the top of the container as part of the top closure.

BRIEF DESCRIPTION OF DRAWINGS

The invention can best be explained further by reference to a number of exemplary embodiments, as illustrated in the accompanying schematic drawings.
In the drawings:

Fig. 1 shows an upper region of a body panel of a first embodiment of container;
Fig. 2 is a perspective view of an upper region of the same embodiment when fully formed, filled and closed;
Fig. 3 is a cross-section corresponding to Fig. 2;
Fig. 4 shows an upper region of a body panel of a second embodiment of container;
Fig. 5 is a perspective view of an upper region of the same embodiment when fully formed, filled and closed;
Fig. 6 is a cross-section corresponding to Fig. 5;
Fig. 7 shows an upper region of a body panel of a third embodiment of container;
Fig. 8 is a perspective view of the third embodiment when fully formed and filled;
Fig. 9 shows an upper region of a body panel of a fourth embodiment of container;
Fig. 10 is a perspective view of the fourth embodiment when fully formed and filled;
Fig. 11 shows an upper region of a body panel of a fifth embodiment of container;
Fig. 12 is a perspective view of the fifth embodiment when fully formed, filled and tensioned;
Fig. 13 is a cross-section corresponding to Fig. 12;
Fig. 14 shows an upper region of a body panel of a sixth embodiment of container;
Fig. 15 is a cross-section of the upper region of a container formed from the panel of Fig. 14, when filled;
Fig. 16 shows an upper region of a body panel of a seventh embodiment of container;
Fig. 17 is a perspective view of the seventh embodiment when fully formed and filled;
Fig. 18 is a cross-section corresponding to Fig. 17;
Fig. 19 shows an upper region of a body panel of an eighth embodiment of container;
Fig. 20 is a perspective view of the eighth embodiment when fully formed and filled;
Fig. 21 is a cross-section corresponding to Fig. 20.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In the manufacture of preferred embodiments of flexible intermediate bulk containers in accordance with the present invention a body panel of tubular woven polypropylene tapes is firstly cut to a selected pattern. Cuts 29 are made down from a top edge of the material to provide bpposing loop or handle forming portions, designated by reference numeral 30 in all the figures, and, between these, opposing flaps, designated by reference numeral 40 in all the figures. Top edges of the respective portions 30 are joined together, typically by stitching for greatest security, so as to provide a loop or handle, designated 31 in all the figures. The material of the handle 31 is preferably gathered together and bound by a sleeve 32, as shown, to provide a well defined handle with a clear aperture therebelow for lifting the eventual filled container. The base of the body panel is closed off in accordance with any conventional pattern. For example, it may be cut appropriately to provide for cross shaped seaming or for overlapping flaps seamed across the bottom, or a separate bottom panel may be inserted. The closure of the base is not relevant to the present invention and is not illustrated.
A liner, designated generally by reference numeral 50, and typically of flexible, substantially impermeable plastics sheet material is inserted into the container, for subsequent filling. Such containers are commonly used for powdered or granular fertilizers, or other chemicals, and it is important that these are kept dry within the liner.
Between 50% and 75% of the material of the body panel, more specifically of the longitudinal tapes of the woven material thereof, extend into the handle 31, with the majority of the remainder, anything from 25% to 50% extending into the flaps 40.
In different embodiments within the scope of the invention the manner of securing the flaps 40 across the top of the container, below the handle 31, varies. Also, in use of said containers, the time at which securement of the flaps takes place varies, i.e. prior to or after filling the containers. The drawings show some of the main variants.
In the first illustrated embodiment, in the initial body panel (Fig. 1), the flaps 40 are cut shorter than the flanking handle forming portions 30, but each flap 40 is long enough to extend more than half way across the width of the top of the filled container (Figs. 2 and 3). One of the flaps is provided with a pair of tie tapes 41 extending from its free upper edge and two rows of slits 42 are cut in corresponding positions in the lower region and/or below the extent of the opposing flap 40. For supply to customers the container shown in Fig. 1 will have the top edges of the portions 30 secured to each other by stitching to provide a lifting loop 31 above the flaps 40, as shown in Fig. 2 and as already mentioned. Also, the liner 50 will be inserted therein, with its mouth possibly temporarily engaged by one of the cuts 29.
After the liner 50 is filled, and its top edge margins or neck region, above the level of filling, suitably folded over and secured, the flaps 40 are pulled tight across the top thereof and secured. The flap with the tie tapes 41 is uppermost and partially overlaps the other flap. The tapes 41 are secured by threading through any of the corresponding row of slits 42 and being tied.
In this way, the top of the liner 50 is protected by the overlying, overlapping flaps 40. Moreover, when the latter are pulled as tightly as possibly across the top of the filled container, the liner is especially well protected against wind damage as it is not free to billow. A more clearly accessible aperture for lifting purposes also results when the flaps are pulled tightly across the container top as well as a more stable and compact package for storage, particularly outdoor storage in windy conditions.
The second illustrated embodiment (Fig. 4 to 6) differs from the first only in that the flaps 40 are secured, after filling, by adhesive at 43 instead of by tie tapes.
In the remaining six illustrated embodiments the flaps 40 are joined to each other prior to filling of the container.
In the third embodiment shown in Figs. 7 and 8, the upper edges of the opposing flaps 40 are stitched to each other at 44. An additional central slit or V-shaped cut-out 45 in each flap 40 provides an opening through which the neck of the liner 50 can be pulled for filling purposes. In this embodiment, the depth of the cuts 29 and/or the length 1 of the flaps 40 should be chosen to allow minimum ullage within the top of the filled container, above the expected fill height 60, commensurate with a reasonably well secured top closure to the filled container. Inevitably, however, the top closure extending across below the lifting loop will not be as taut as when the flaps are pulled over and secured after filling and settling of contents. After filling, the neck of the liner can be closed off, if required, and can be tucked back through the opening provided by the slits 45.
The fourth embodiment shown in Figs. 9 and 10, differs from the third embodiment only in that there is no special provision for an opening through which the neck of the liner 50 can protrude for filling purposes. In this case, the liner neck simply protrudes from one side of the joined flaps 40.
The fifth embodiment, shown in Figs. 11 to 13, is similar to the third, but additionally incorporates tie tapes 41 so that the flaps 40, which are stitched together at 44 prior to filling, can be pulled tight across the top of the container after filling. As in the first embodiment, the tapes 41, can be secured by being threaded through any of a series of appropriately positioned slits 42 and tied back on themselves. The slits 42 in this case may be on or below the flap 40 which carries the tie tapes 41. As indicated in Fig. 13, the pulling tight will involve the folding over at 46 of the connected flaps 40 to provide multilayer protection for the top of the liner 50, the neck of which is tucked back below the flaps 40, as previously. With this arrangement, the depth of the cuts 29 or length of flaps 40 is not critical, as slackness is taken up in the post-filling tightening operation.
In the sixth embodiment, illustrated in Figs. 14 and 15, the opposing flaps 40 are each provided with a central slit 45, in the manner of the third embodiment. However, their upper edges, at respective sides of those slits 45 are connected by way of respective panels 47 of stretchable or elastic material. These panels 47 may be of any suitable elasticated or knitted material, or resilient sheet material, and they are conveniently sewn in between the upper edges of the flap portions, as shown in Fig. 14, L, L' connecting to A, A' and M, M' to B, B' at one side, and N, N' connecting to C, C' and O, O' to D, D' at the other side. An opening for the neck of the lining 50 to protrude through for filling purposes is provided by the slits 45 and between the panels 47 and after filling the neck is tucked back below the flaps and panels as shown in Fig. 15.
Upon filling of the container, the panels 47 will stretch and their inherent resilience will maintain the tightness of the top closure, and the advantages accruing thereto as regards stability of the filled container in windy conditions.
Of course, in modifications, only a single elastic panel may be provided to connect the upper edges of the flaps, with no specific opening for the liner neck, which can protrude from one side of the flaps instead.
In the seventh embodiment, illustrated in Figs. 16 to 18, the flaps 40 are of equal length to the loop forming portions 30, thus making use of all the material of the initial tubular woven body panel. The flaps 40 are overlapped for substantially the entire width of the container top and upper flap is secured by stitching, at 48, prior to filling. Slits 49 are cut centrally in each of the flaps 40 and so are in approximate alignment, to provide an opening for the liner neck, when the flaps 40 overlap each other.
In the eighth embodiment (Figs. 19 to 21) the initial body panel is identical to that of the preceding embodiment (Fig. 16), but each flap 40 is folded back on itself prior to seaming. Thus, a central seam is produced at 58 (Fig. 20) in place of the seam 48 in Fig. 17.
The invention is not limited in any way to the precise details of the manner of top closure illustrated in any of the drawings. The illustrated embodiments which have been briefly described serve merely to indicate a few of the main variants encompassed within the general scope of the invention. There are numerous other possibilities and combinations of features which will be readily apparent to anyone skilled in the art. Only a few are mentioned in the following passages.
Side edges of the flaps may, in appropriate cases, be secured to the base of respective sides of the lifting loop. This would, however, introduce greater complexity to the manufacture of the containers.
Although stitching, adhesion and use of tie tapes have been referred to as most convenient, advantageous or cost effective manners of securing the flaps across the top of the container, either prior to or after filling, other manners of securement, e.g. by fasteners such as staples, are not precluded, and any combination of the various manners of securement is possible.
The various ways illustrated of providing an opening for protrusion of the liner neck are not exhaustive. A slit or slot elongate in a direction longitudinally of the body panel material, thus through the lifting aperture of the finished container, is preferable as it minimises weakening of the container material, whilst allowing a reasonable size for manipulation of the liner neck therethrough and for filling therethrough. A slit or slot orientated transversely or a gap left in a seam of stitching, or in a line of adhesive whereby the flaps are secured together are possible alternatives, but are less desirable as they entail an increased risk of lifting means catching in the opening. Alternatively, no special provision may be made and the liner neck may project to one side of one or both flaps, (as in some of the illustrated embodiments); or the liner may be filled from the base of the container so that it does not need to have a neck protruding at the top.
The flap portions which form the top closure are conveniently of equal size, but need not be. In length, each flap is preferably at least 60% and up to 100% of the width of the top of the filled container to allow an advantageous overlap or double thickness of from 20% up to 100%.
Although the initial body panel is shown in all the illustrated embodiment with the handle forming portion 30 flanking the opposing flaps 40 for top closure, it is quite feasible to produce the container from an initial cut panel where the handle forming portions are central and the flaps are at respective sides thereof. This is simply a transposition of parts through 90° and is a matter of choice in the manufacturing procedure.
The cuts down from the top of the body panel need not be straight. They may have curvature inwards towards the vertical centre line of the body panel. When joined, and laid flat across the top of a filled container, this curvature would extend the top protection towards the base of the lifting loops. A greater part of the liner would be covered, than would be the case with linear cuts.
Another alternative is to have a serrated or zig-zag edge to the cuts as this will promote fray resistance to the woven material adjacent to the cuts.
Additional cuts down from the top of the base panel could allow for formation of more than one lifting loop, which would still extend above a substantially flat top closure formed by the flaps. In practice, however, there would appear to be little advantage to this.
A container of especially high strength may be produced by using two layers of body material instead of one in any of the foregoing embodiments. In this respect, an initial tube of material may be cuffed back upon itself or, more simply, one body panel may be inserted inside another at the outset. The two layers can then be cut and seamed simultaneously to produce the final container with lifting loop or loops, and with double thickness top closure.

Claims

A method of manufacturing a flexible container of the type having side walling of tubular form and at least one lifting loop (31) which is an integral extension of the side walling, comprising the steps of cutting the side walling from the top edge thereof to provide at least two portions (30) and at least two flaps (40) in the upper regions of the side walling, and joining together the top edges of said portions (30) to form the lifting loop or loops (31), characterised by slits (29) in the side walling defining said portions (30) and flaps (40), and by the steps of extending the flaps (40), which do not contribute to the loop or loops (31), across the top of the container below the lifting loop or loops (31), and securing them in position to provide a substantially laid flat closure to the top of the container.
A method as claimed in claim 1 wherein the side walling of the container consists of woven material having longitudinal and transversely extending interwoven strands, and the portions (30) which are joined at their top edges to provide the lifting loop or loops (31) include between 50% and 75% of the longitudinal strands, with between 25% and 50% of the longitudinal strands extending into the flaps (40) which provide the closure to the top of the container.
A method as claimed in claim 2 wherein the side walling consists of material which is woven in tubular form.
A method as claimed in any one of claims 1 to 3 wherein the flaps (40) are secured to each other by stitching (44, 48, 58) or by adhesion (43).
A method as claimed in any one of claims 1 to 4 wherein an opening remains between the respective flaps (40) to enable filling access and/or protrusion therethrough of a neck of a liner (50) of the container.
A method as claimed in any one of claims 1 to 4 wherein an opening (45, 49) is provided in at least one of the flaps to enable filling access and/or protrusion therethrough of a neck of a liner (50) to the container.
A method as claimed in claim 6 wherein the opening is in the form of a slit (45, 49).
A method as claimed in any one of claims 1 to 7 wherein side edges, or at least portions of side edges, of the laps (40) are secured to the base of the lifting loop or loops (31).
A method as claimed in any one of claims 1 to 8 wherein, prior to securing the flaps (40) across the top of the container, the container is filled with material.