Patent Application
20180194549
The invention relates to a flexible storage device for packaging bulk solids. The field of the invention is that of large containers for packaging of large quantities of particulate solids, also called bags GRVS bags (from the French “Grand Récipient Vrac Souple”) or FIBC bags (Flexible Intermediate Bulk Containers). These storage devices have been known for many years and used for protection, storage and transport of particulate bulk materials such as food materials (sugar, flour, starch), granulated polymers or chemical products.
These containers are conventionally polymer fibres fabric (for example PP, HDPE, LLDPE), optionally sealed. The capacity of these containers is generally between 0.5 and 2 m3. The size and weight of large containers, once filled, makes handling difficult, in some cases even dangerous. In practice, for optimal use of storage space, the filled bags are stacked in several layers; it is thus essential to ensure stability when stacked.
According to the experience of the Applicant, in time, the particulate matter continues to settle and move in the container, thereby deforming the flexible container in a position which often deviates from the vertical, and which may lead to imbalance. These containers typically have a rectangular bottom, often square, and rectangular vertical sidewalls, which should allow, when the bags are juxtaposed, optimum filling of the available storage space. In practice, the pressure exerted on the particulate matter deforms the side walls outwardly, the filled container deviates from its ideal parallelepiped shape. The footprint of the container is thus greater than the square or rectangular base dimensions. Thus, in a lorry with a floor area of 32 m2, it is not possible to juxtapose more than 24 filled containers, each with a square base of 1 m, without subjecting them to a strong tamping while loading which can cause damage.
However, the state of the art of flexible large bulk containers, especially WO 92/14660 to WO 92/21572, or WO 2010/130961A, reveals a substantially parallelepiped shape, the resistance to deformation and stability of which when filled is improved by internal, flexible, stabilizing elements.
For this purpose, flexible, vertical walls, inside the storage volume of the container, connect the side walls to one another and dividing the storage volume in a plurality of vertical compartments, namely a central compartment and four peripheral compartments.
In the containers of WO 92/14660 or that of WO 2010/130961, the edges of the partitions defining the upper mouth of the central compartment are positioned below the upper edges of the side walls of the container so as to constitute overflows during filling. The filling of such a container takes place by pouring particulate material from the top, into the central compartment, the material first filling the central compartment, and then filling the peripheral compartments by discharging into the overflow.
The pre-filling of the central compartment allows, due to the pressure of the particulate matter on the walls, to cleanly and uniformly stabilize the flexible walls of the central compartment, and before the material is poured into the peripheral compartments.
Once filled, the stability in time of the container is substantially improved compared to a conventional container (without a stabilizing element) in that it does not deviate from the vertical when placed on the floor, limiting the tipping risks of the container. Furthermore, the flexible walls connecting the side walls (to one another) limit the extent of the deformations of the side walls of the container outwardly. The size of the filled container is improved, optimizing the storage capacity.
In this prior art, the flexible partition stabilizing elements are, just as the walls of the flexible container, typically made of polymer fibre fabric (for example PP, HDPE, LLDPE), optionally made more or less air-tight by coating or lamination.
For longer storage periods, however, there is a risk of moisture uptake of the contents through the walls of the container from the external environment. According to the Applicant's findings, this moisture uptake can lead to the formation of lumps in the container, which interfere with the smooth flow of material through the bottom opening of the container once opened. In this case, and prior to the unloading of the container, it may be necessary to decake the contents of the container by mechanical operations on the external walls of the container. These decaking operations are undesirable in that they complicate unloading of materials and also constitute a damage risk to the container.
The container of WO 92/14660 discloses, however, in
The structure of the storage device of WO 92/14660 likewise comprises a container forming the bottom and four side walls of the container, typically made of fabric. Each sidewall of the container is formed by two flexible halves joined to each other by a vertical seam connecting the joint edges thereof 23. Each flexible half, furthermore has, at the upper corners of the container, a suspension loop. The device's four suspension loops can lift the filled device, conventionally by means of a lifting system.
The internal stabilizing element is constituted by a flexible tubular member, having four vertical seams, thereby forming a flexible tube the internal volume of which forms the central compartment, and four vertical strips 7 distributed at 90° around said tube, intended to be fixed respectively to the four side walls of the bag. To this end, each vertical edge of strip 7 is sandwiched between the two joint edges 23 and traversed by the same fastening seam. The inner liner 28 in
The known flexible intermediate bulk containers of WO 92/21572 is designed to meet the problems of optimization of storage space, security, and moisture uptake, as identified above.
To this end, the flexible intermediate bulk container of this prior art includes three subsets, namely, as shown in
A flexible container, typically made of fabric forming a rectangular bottom and four rectangular walls, provided with four suspension loops to ensure the handling of the container,
An insert 12 forming stabilization means with the creation per se of vertical filling compartments, i.e. a central compartment, and four peripheral compartments
An inner lining 15 interposed between the inner walls of the bag and the outer walls of the insert to make the container impermeable.
The insert is a flexible member comprising an outer envelope covering the side walls of the bag, and may be provided, as in the embodiment of
According to the Applicant's findings, the presence of holes 32 does not provide, as do the containers of the above-mentioned documents, the required tension for the flexible walls forming the central compartment. On the contrary, according to the findings of the Applicant, in the bulk containers on the market, the wall of the tube forming the central compartment is provided with large holes (of the order of 10 cm or more), the tension is irregular along the upper part of the tube, giving rise to folds, extending over the upper part of the tube, which are then copied to the wall of the outer envelope of the insert when the material fills the peripheral compartments. The filling of the container is thus not optimal. After filling the container, and according to the findings of the inventor, the fabric of the side walls of the container is folded along the direction of the height.
According to the embodiment of
According to the findings of the inventor each fastening element 25 is itself a tubular element comprising two walls 33 (“bar 33”) extending from the tube 34, both connected to a wall 35 (“bar 35”), forming the distal end of the element 25, this distal end being fixed by two spaced welds 37 to the outer envelope.
In summary and according to the findings of the Applicant, such a bulk bag, as disclosed in WO 92/21572, has the following disadvantages:
The container requires three distinct sub-unit, namely, a bag, an insert, and an inner liner seal, for making the container impermeable when the bag is not itself an impermeable bag,
The holes 32, distributed over the upper part of the wall of the central tube providing the discharge of the particulate material from the central compartment to the four peripheral compartments, cause wrinkles during filling, not only on the upper part of the tube centre of the insert, but also to the insert of the outer envelope,
The fastening elements (“strip 25”) of the embodiment of
The purpose of the present invention is to overcome the above drawbacks by providing a flexible storage device for packaging bulk solids, with a footprint that is close to rectangular or square when filled so as to optimize storage capacity when the containers are juxtaposed, with increased security against the risk of tipping, and preferably, at least according to one embodiment, suitable for limiting the moisture uptake of the contents.
Another object of the present invention is to provide such a structural device such that it can be manufactured at a limited production cost.
Other objects and advantages of the invention appear from the following description which is given for reference only and is not intended to limit same.
The invention relates to a flexible storage device for the packaging of particulate solids having a bottom and side walls defining a substantially parallelepiped storage volume, the device comprising:
Suspension loops in the upper part for lifting
a unit comprising:
According to optional features of the invention taken alone or in combination:
the storage means comprises a flexible container, comprising a bottom and at least two side walls, said suspension loop being secured to the upper portion of said flexible container, and wherein said unit is a separate member of said flexible container, provided as an insert between the bottom and side walls of said flexible container;
said flexible container consists essentially of said bottom wall, and two side walls only, substantially parallel, covering two of the four side walls of the outer envelope, and so that the other two side walls of the outer envelope are not covered by the walls of said container;
the outer envelope of the received unit as an insert into the container has no bottom, said bottom of the container being fixed to the side walls of the outer envelope, the container bottom and side walls forming the storage volume of the solid materials;
the container material is a web of raw, coated or laminated polymer fibres;
the outer envelope forming said bottom wall of the storage volume, both the bottom wall and the side walls of the outer envelope, forming the volume of storage for particulate solid materials;
the bottom wall is provided with a discharge chute formed by the outer envelope, which, in the case where said device comprises said flexible container, goes through an opening in the container bottom;
the outer envelope defines a cover provided with a filling chute;
the suspension loops are secured directly to the corners of said unit;
the inner envelope does not have opening(s) greater than 1 mm in diameter, preferably openings greater than 200 microns in diameter, between the upper edge of the inner envelope and the lower edge of the inner envelope;
the upper edge of the inner envelope, has notches facing different peripheral compartments, favouring the discharge of particulate matter by overflow from the central compartment to the peripheral compartments;
each welding line directly joins the outer envelope forming one of the side walls in the tube wall of the inner envelope defining the perimeter of the central compartment;
the inner envelope and the outer envelope are extruded from a single polymer film that is monolayer or multi-layer;
the polymer film of the inner envelope and/or outer envelope has a thickness of between 50 and 250 microns.
According to one embodiment, the polymer film of the outer envelope and/or the inner envelope is chosen from:
a polyamide/polyethylene complex;
a 100% PE multi-layer;
According to one embodiment, the outer envelope includes at four corners of the storage volume, flaps, that are substantially vertical, along the height of the storage volume, each obtained by welding together two thicknesses of the first polymer film, said vertical flaps being used as a bonding edge or seam edge or to fasten said unit to said container, or to fasten said suspension loops directly to the flaps.
According to an embodiment limiting the risk of explosion associated with the occurrence of electrostatic electrical discharges:
the inner envelope and the outer envelope are insulating, with a surface resistivity greater than 1.0×1012Ω (such as L3, devoid of a static electricity conductive layer and devoid of a static electricity dissipative layer, the envelopes 30, 40 comprising internal and external micro-perforations therethrough spread over their entire surface and so that the breakdown voltage of the entire inner envelope and outer envelope is less than 4 kV, without requiring the device to be grounded,
the material of the container, if any, is an insulator, without antistatic additives, and without an electrically conductive layer, and the breakdown voltage of the container wall being less than 6 kV such that the storage device can be classified as type B flexible intermediate bulk containers according to standard 61340-4-4 Edition 2.0 2012-01.
Alternatively and according to another embodiment, the outer envelope and the inner envelope have a surface resistivity of between 1.0×109Ω to 1.0×1012Ω (type L2) and feature dissipative agents so that the storage device can be classified as type B flexible intermediate bulk containers according to standard 61340-4-4 Edition 2.0 2012-01 when the container is made from an insulating material as defined in the standard, or type C when the container is made from a conductive material.
Alternatively and according to yet another embodiment, the outer envelope and the inner envelope are made from an electrically conductive material with a surface resistivity of less than 1.0×107Ω (type L1) so that the storage device can be classified as type C flexible intermediate bulk containers according to standard 61340-4-4 Edition 2.0 2012-01
The invention further relates to a method of manufacturing a storage device according to the invention, wherein said unit is obtained at least by the implementation of the following steps:
a first polymer film is provided that is intended to constitute the outer envelope and a second polymer film, preferably in the form of a tubular sheath of the lower perimeter, optionally provided with discharge notches, intended to constitute the inner envelope,
welding the second polymer film inside a tubular sheath formed by the first polymer film obtaining two coaxial flexible sheaths respectively formed by the first and the second polymer film, the two sheaths being fixed one into the other at at least four first weld lines.
According to one embodiment, vertical flaps are formed at the four corners of the storage volume of the outer envelope, each obtained by welding together two thicknesses of the first polymer film.
According to one embodiment of the method, the unit having a bottom provided with a discharge chute and/or a cover provided with a filling chute and the bottom is obtained with a discharge chute and/or said cover with a filling chute by the following successive steps:
welding together two thicknesses of the first polymer film at four or eight corners of the sheath, each of the welds, called second welds, extending from the edge to one of the mouths of the sheath and to a longitudinal edge of the sheath, thereby obtaining the filling chute and/or the discharge chute,
the angles of the sheath are removed by cutting the first polymer film along and on the outside of the second welds.
The invention also relates to a process for packaging the solid (or liquid) bulk materials comprising the deposit of a particulate solid material in bulk (or alternatively a liquid) from above into the central compartment of a flexible storage device according to the invention, the material (or liquid) filling said first central compartment, and then, by overflow over the upper edge of the inner envelope only, filling the four compartments.
The invention will be better understood from reading the following description accompanied by the figures attached hereto among which:
The invention relates to a flexible storage device 1, 1′, 1″, 1′″ for packaging particulate solids having a bottom and side walls defining a substantially parallelepiped storage volume. Optionally, the storage device has a cover 35, which closes the storage space from above.
Such a storage device 1, 1′, 1″, 1″′ comprises:
the suspension loops 25 in upper part intended for lifting
The outer envelope 30 consists essentially of a first polymer film and the inner envelope 40 consists essentially of a second polymer film, said vertical attachment lines being the weld lines between the first polymer film and the second polymer film. The first polymer film and/or the second polymer film are typically obtained by extrusion or co-extrusion when the first film and/or the second film are complex, i.e. multiple layers of the same polymer material or of several different polymers.
Weld lines, at least four in number, can be of a width between 5 mm and 20 mm. These weld lines may be optionally doubled.
As shown but not limited to the examples of the figures, each weld line can directly join the outer envelope 30 forming one of the side walls 31, 32, 33, 34 to the tube wall of the inner envelope 40 defining the perimeter of the central compartment C1.
The inner envelope 40 has an upper edge 50 defining the upper mouth of said central compartment C1 and a lower edge 51 defining the lower mouth of said central compartment C1. The upper edge 50 of the inner envelope 40 is located at the same height of the upper edge of the side walls 31, 32, 33, 34 of the storage volume, or below the upper edge of the side walls 31, 32, 33, 34 of the storage volume, so that the upper edge 50 of the inner envelope is an overflow allowing the discharge of material from the central compartment C1 to the peripheral compartment C2 to C5.
The filling of the device of the storage volume is obtained by discharge of a bulk particulate solid (or liquid) from above into the central compartment C1, the material first filling said central compartment C1, then by overflow of material over the upper edge 50 of the inner envelope 30, the four peripheral compartments C2, C3, C4, C5.
Preferably, the inner envelope 40 has no opening(s) of diameter greater than 10 mm, even none greater than 1 mm, preferably without an opening with a diameter greater than 200 microns, between the upper edge 50 of the inner envelope 40 and the lower edge 51 of the inner envelope 40. The side wall of the central compartment is C1 and impermeable to the particulate material so that the discharge of material from the central compartment C1 to the peripheral compartments C2 to C5 takes place only above the upper edge 50 forming overflows, not through holes in the wall of the central compartment as taught by the device of WO 92/21572, these holes being referenced as 9 in
According to the findings of the inventor, the absence of such holes enables uniform stretching of the wall of the central compartment C1, and contrary to the teaching of WO 92/21572, the holes create an uneven tension in the wall of the central compartment depending on the height, with the formation of folds on the upper part during filling, which are then copied when the peripheral compartments are filled.
The inner envelope 40 may optionally be perforated, but only in order to promote de-aeration of the storage volume, and/or, and as will be described later in order to limit the breakdown voltage of unit 3: in both cases, the perforations are micro-perforations the diameter of which is determined so as to be impermeable to the particulate material.
In a first embodiment, illustrated in, though not limited by, the examples of
According to this first embodiment, the unit 3 is then a distinct member of said flexible container 2, scheduled for insert between the bottom and side walls of the flexible container. The side walls 31, 32, 33, 34 formed by the outer envelope 30 of the unit are respectively covered, wholly or partly, by the side walls of the flexible container 2.
According to one embodiment, illustrated in, though not limited by,
According to another embodiment, illustrated in, though not limited by,
According to one embodiment, illustrated in, though not limited by, the examples of
The bottom wall 38 may be provided with a discharge chute 36, which, in the event that said device has said flexible container 2, goes through an opening 26 in the bottom 20 of container 2. The outer envelope 30 may also define a cover 35 provided with a filling chute 37. The filling chute 37 and/or the discharge chute 36 can be closed by tying. A method of manufacturing a unit comprising a bottom 38 provided with a discharge chute 36, and/or a cover 35 provided with a filling chute 37 is described hereinafter.
In the event that said outer envelope 30 forms a cover 35 and a bottom 38 forming the side walls 31, 32, 33, 34, a storage volume that is impermeable to the particulate material, the storage device may advantageously be devoid of said container 2, typically made of fabric. The suspension loops 25 are then secured directly, rigidly connected to said unit 3, typically at the four corners of the storage volume.
Such an embodiment, illustrated in, though not limited by,
According to another embodiment, illustrated in, though not limited by,
According to one embodiment, the upper edge 50 of the inner envelope 40 has notches 52, in particular in V shape, facing the various peripheral compartments C2 to C5, favouring the discharge of particulate matter by overflow from the central compartment C1 to the peripheral compartments C2 to C5.
According to one embodiment, the polymer film of the inner and/or external envelope is a wall that is between 50 microns and 250 microns thick, preferably between 90 microns and 150 microns, such as 120 microns.
The inner envelope 40 and/or the outer envelope 30 are preferably made from a single monolayer or multi-layer film, to facilitate the recycling of the unit 3.
The polymer film of the outer envelope 30 and/or the inner envelope 40 may be chosen from:
a complex of polyamide/polyethylene
a 100% polyethylene multi-layer,
a polyolefins complex of the same or of different types, including such EVOH,
a complex of polyolefins and aluminium.
According to the filling tests conducted by the Applicant, good results have been obtained with a polyamide/polyethylene complex (PA/PE), and more particularly a multi-layer (PE/binder/PA/binder/PE), i.e. comprising a polyamide layer between two polyethylene layers and two layers of binder respectively interfacing between the polyamide layer and the corresponding layers of polyethylene and a PA/PA/PE film on the same principles as before.
Such a film tested, with a thickness of 120 microns, was able to constitute a good barrier to moisture from the outside environment. Due to the low elongation under load of this polyamide/polyethylene complex, the unit showed good performance in filling, limiting the amplitude of the outward deformations of the side walls of the outer envelope, under pressure of the material and by comparison to a set of the same design wherein the first and second film are made of polyethylene only.
In general, the outer envelope 30 may have flaps B1, B2, B3, B4 that are substantially vertical, the four corners of the storage volume, on the height of the storage volume. Each of the flaps B1, B2, B3, B4 is obtained by welding together two thicknesses of the first polymer film.
These vertical flaps B1, B2, B3, B4 are used as a bonding edge or seam edge to fasten said unit 3 of said container 2 of the container, for example, as represented by the embodiment of
These flaps B1, B2, B3, B4 can still be used to directly fasten said suspension loops 25, and as illustrated, by way of example and in a non-limiting fashion, in
Furthermore, different construction arrangements can be used to limit explosion risks linked to the occurrence of electrostatic discharge.
According to one embodiment:
The inner envelope and the outer envelope can be insulating, having a surface resistivity greater than 1.0×1012Ω, devoid of static electricity conductive layer and static electricity dissipative layer, the inner and outer envelopes 30, 40 comprising micro-perforations, preferably through-holes, spread over the entire surface thereof and so that the breakdown voltage of the entire inner envelope and outer envelope is less than 4 kV without requiring the grounding of the device,
the material of the container, if needed, is an insulator, without antistatic additives, and without an electrically conductive layer, with the breakdown voltage of the container wall being less than 6 kV so that the storage device can be classified as type B flexible intermediate bulk containers according to standard 61340-4-4 Edition 2.0 2012-01.
The diameter of the micro-perforations may be between 5 microns and 130 microns, for example between 5 microns and 40 microns (μm). The diameter of microperforations is chosen according to the particle size of the material to be stored and to prevent the material from passing through the wall of the outer envelope 30 or of the inner envelope 40. The density of the microperforations on the outer 30 and inner 40 envelopes is between 0.2 perforations per cm2 and 2 perforations per cm2 and are preferably uniform.
Advantageously, such a storage device offers increased security against the risk of dangerous electrostatic discharge, and without requiring dissipative agents likely to migrate to the stored product and contaminate same, and without requiring the grounding of the storage device during filling or emptying operations. For more details regarding making micro-perforations, a person skilled in the art can refer to the patent application PCT/FR2014/051836 of the present applicant.
According to another embodiment, the outer envelope 30 and inner envelope 40 have surface resistivity of between 1.0×109Ω to 1.0×1012Ω (L2 type), i.e. devoid of dissipative agents so that the storage device can be classified as type B flexible intermediate bulk containers according to standard 61340-4-4 Edition 2.0 2012-01 when the container is made from an insulating or dissipative material under of the standard, or type C when the container is made from a conductive material. Such embodiment does not require the grounding of the storage device during filling and emptying for type B, but contains dissipative agents likely to migrate the stored products.
In yet another embodiment, the outer envelope 30 and inner envelope 40 are made from an electrically conductive material having surface resistivity less than 1.0×107Ω (L2 type) so that the storage device can be classified as type C flexible intermediate bulk containers according to standard 61340-4-4 Edition 2.0 2012-01. Such a device, however, requires the grounding of the storage device during filling or emptying operations and safety measures against electric shock risks.
The invention further relates to a method of manufacturing a storage device according to the invention, wherein said unit 3 obtained at least by the implementation of the following steps:
a first polymer film is provided that is intended to constitute the outer envelope 30 and a second polymer film, preferably in the form of a tubular sheath of smaller diameter, optionally provided with discharge notches 52, intended to form the inner envelope 40 (see
welding the second polymer film inside a tubular sheath formed by the first polymer film obtaining two coaxial flexible sheaths respectively formed by the first and the second polymer film, the two sheaths being fixed one into the other, at first four weld lines 41-44 (see
These steps allow to obtain said unit, with the outer envelope 30 and inner envelope 40 which mutually define the vertical compartments (C1 to C), namely the central compartment C1, and peripheral compartments C2 to C5.
Optionally, and prior to these two steps, the first polymer film and the second polymer film can be perforated over the entire surface thereof uniformly, the preferred diameter of said microperforations being between 5 microns and 130 microns and preferably having a density of between 0.2 perforations per cm2 and 2 perforations per cm2, as described above.
Each of the two tubular sheaths may be obtained from the first polymer film (or second polymer film), originally in the form of a sheet, which is folded onto itself and the two edges of which are welded in order to obtain the sheath. In another alternative, the first polymer film and/or the second polymer film can advantageously be a bellows sheath extruded one piece from the outset.
Thus, according to one embodiment shown in
The process may also have an additional step in which vertical flaps B1, B2, B3, B4 are formed on said unit, which will then be used as a bonding edge or seam edge as explained hereinbefore.
Thus, and as illustrated without limiting effect in
When said unit has a bottom wall 38 provided with a discharge chute 36 and/or a cover 35 provided with a filling chute 37, the bottom 38 can be obtained with discharge chute 36 and/or said cover 35 with a filling chute 37 by the following successive steps:
welding together two thicknesses of the first polymer film at four or eight corners of the sheath, each of the welds, called second welds, extending from the edge to one of the mouths of the sheath to a longitudinal edge of the sheath, thereby obtaining the filling chute and/or the discharge chute (see
the corners of the sheath are removed by cutting the first polymer film along and on the outside of the second welds (see
The four upper welds (S1, S2 and S1′, S2′) are used to make the cover 35 with the filling chute 37 thereof, and the lower four welds (S3, S4 and S3′, S4′) are used to make the bottom with the discharge chute 36. Only the upper welds (S1, S2 and S1′, S2′) or lower welds (S3, S4 and S3′, S4′) or all eight can be made, as required.
Of course, other embodiments could be contemplated by a person skilled in the art without departing from the scope of the invention defined by the claims below.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15 57060 | Jul 2015 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2016/051915 | 7/22/2016 | WO | 00 |
