[0001] This invention relates to intermediate bulk containers (IBC's), and in particular
to flexible intermediate bulk containers. Such flexible containers, which typically
have a capacity of 0.5 to 3 m³, are generally in the form of sacks or bags and are
widely used for the packaging, for transport and storage, of particulate materials,
for example chemicals and fertilisers in bulk quantities. Typically when filled a
flexible container has a cylindrical configuration of diameter 0.8 to 1.5 m and a
height of 0.5 to 1.5 m.
[0002] In EP-A-80839 there is described an arrangement consisting of a flexible intermediate
bulk container and a cradle therefor to support outer portions of the base of the
intermediate bulk container above the surface on which the base rests. The cradle
enables the tines of a fork-lift truck to be inserted beneath the outer portions of
the base of the intermediate bulk container so that the latter, preferably together
with the cradle, can be lifted. The flexible intermediate bulk container of the present
invention need not be used in conjunction with such a cradle, but it is particularly
beneficial when it is so used. By the use of an arrangement of flexible intermediate
bulk containers and cradles it is possible to stack several cradle/filled bag combinations
one above another.
[0003] Flexible intermedite bulk containers are widely used in industry and the market for
these runs into millions of pounds. Accordingly there is a constant desire to simplify
the manufacture of the containers in order to achieve a more efficient use of labour
and to achieve as high a degree of automation as possible in the manufacturing process
for accuracy and repeatability. Furthermore there is a continual desire to minimise
wastage of material in the cutting and preparation of the containers, thereby reducing
the costs.
[0004] It is a problem of the art to simplify the manufacture of containers and to minimise
material wastage whilst maintaining the necessary properties of the container. A flexible
intermediate bulk container has to be sufficiently strong to carry typically 0.5 to
3 m³ of material. If stacked, as preferred, the containers have to withstand considerable
hoop stresses to enable a stable stack to be made. In addition it is generally desirable
that the container, when used for fertiliser or the like, is impervious in order to
protect the container contents from the weather.
[0005] Accordingly the present invention provides a flexible intermediate bulk container
comprising a single piece of tubular material having a side wall of generally cylindrical
configuration, when filled, said side wall having at least two double-walled portions,
having single walled portions spaced between said double-walled portions, at least
two of said double-walled portions having a flap extension, said two or more flap
extensions being joined to form a base to said container.
[0006] Preferably there are two diametrically opposed double-walled portions each of which
comprises about a quarter of the cylindrical side wall, that is a 90° segment. Each
of said double-walled portions has an integral flap extension. The two flap extensions
are fastened together so as to form a base to the container. Conveniently the two
flap extensions are fastened together at a region equidistant from the respective
side walls from which they integrally extend. Conveniently the flap extensions extend
from both the inner and outer walls of each of said double-walled portions so that
the base of the container is double-walled.
[0007] It can be seen that as the container is formed of a single piece of tubular material,
the contruction of the present invention requires only one region of fastening. This
is advantageous because the cost of fastening and the labour involved is a significant
factor in the economics of the manufacture of intermediate bulk containers.
[0008] The fastening may be in any convenient way, for example stitching with a suitable
thread, and/or using a layer, line or spots of adhesive and/or an adhesive tape or
patch.
[0009] The base to the container is formed by fastening, with, in a preferred embodiment,
about half of said base connected to the side wall by being integrally formed. Therefore
about half of the said base is not connected to the side wall thus forming diametrically
opposite gaps. In use the side wall assumes a generally cylindrical configuration
and the base of the container assumes an approximate square configuration. The diametrically
opposite gaps between the base and side wall can be closed by fastening means. This
is not preferred as this introduces two further operations into the manufacture of
the container. In a preferred aspect the gaps are not closed; the particulate material
being stored or transported being held in an inner liner. Conveniently this inner
liner is of a plastics material and, of course, the liner prevents particulate material
from escaping through the gaps between the base and side wall of the container. The
inner liner need not be very strong as the outer tubular material forming the container
withstands the stresses imposed upon the system. Preferably the inner liner is fastened
to the container, for example by means of an adhesive, during the manufacture in order
to ensure accurate positioning of the liner. The fastening need not be overall; indeed
the liner may be simply held in place by a line, or spots, of adhesive.
[0010] The tubular material is preferably a fabric woven from fibres or tapes of a natural
or synthetic material, for example of of fabric weight 100 to 200 g.m⁻², such as a
polyolefin tape, for example a high density polyethylene or oriented polypropylene.
Alternatively the tubular material can be a film of plastics material, preferably
an oriented film. In the latter case the direction of maximum orientation in the film
should be parallel to the hoop direction of the container.
[0011] The inner liner, if present, is preferably an impermeable film of a plastics material.
It need not be very tough but is preferably of waterproof material.
[0012] As has been previously mentioned the flexible intermediate bulk containers of this
invention can be used with a cradle. The supporting cradle generally comprises a pair
of supporting members disposed beneath the base of the container so that the container
can sag into the space between the supporting members to a depth substantially equal
to the height of the cradle, the supporting members being connected so that the maximum
spacing between said supporting members, and their height, is sufficient to permit
the interaction of the times of a fork-lift truck with the supporting members to permit
lifting.
[0013] When the container is filled and resting on a cradle as aforesaid, the bulk of the
weight of the container contents, and of any container/cradle combinations stacked
on top thereof, is borne through the base of the container directly on to the surface
on which the container and cradle are resting. However, upon lifting the container
either alone or together with the cradle, by fork-lift truck tines disposed under
the outer portion of the base of the container, the bulk of the load is transmitted
directly to the parts of the base supported by the fork-lift truck tines as a result
of frictional forces between the particles of the material within the container.
[0014] In general the containers of the present invention are designed to be handled by
means of the supporting cradle. However, in some cases the end user may wish to lift
the container from the supporting cradle prior to, or during, emptying. Such lifting
can be accomplished by direct lifting of the double-walled portions of container,
where of course there is greater strength, for example using conventional lifting
gear such as clamps or the like. However in a preferred aspect of this invention a
separate web or rope may be inserted into the double walled sections. Such a web or
rope is accessible to the end user in the single-walled regions and may be lifted
by lifting gear.
[0015] In another aspect of this invention, suitably the container has at least one area
having reinforcing threads woven in it. More suitably there is a plurality of such
areas. These areas having reinforcing threads provide additional strength and facilitate
the lifting from above of the container by the end- user's lifting gear. Conveniently
these areas having reinforcing threads are provided in the form of bands running in
the warp direction of the sleeve, that is from top to bottom.
[0016] In the case wherein there is a separate web or rope inserted in the partially double-walled
embodiment, the regions of greatest stress on lifting are at the ends of each double-walled
portion. Therefore it is preferred that the bands of reinforcing threads are positioned
to strengthen these regions, acting as a "rip-stop".
[0017] The container is made from a single piece of tubular material so that the bottom
of the container also has bands of reinforcing threads.
[0018] The reinforcing threads are conveniently of any sythetic polymer, such as polyester,
polyolefin or polyamide.
[0019] By way of Example only, one embodiment of the invention is illustrated by reference
to the accompanying drawings wherein
Figure 1 is a side view of a length of tubular material,
Figure 2 is a perspective view of the same length of tubular material,
Figure 3 is a schematic view of a partly constructed container,
Figure 4 is a perspective view of the construction of Figure 3,
Figure 5 is a plan view of a constructed container,
Figure 6 shows detail of an embodiment incorporating lifting loops,
Figures 7 to 10 show the stages in formation of an inner liner,
Figure 11 shows a container in combination with an inner liner and supported by a
cradle,
Figure 12 is a perspective view of a cradle, and
Figure 13 is a side view of a length of tubular material showing how a number of containers
can be cut.
[0020] In Figure 1 there is shown a length of tubular woven polypropylene 1 having bands
2 of reinforcing threads running in the warp direction. The single piece of tubular
material is shown in perspective in Figure 2 with the reinforcing threads omitted
for greater clarity. The tubular material is cut along lines AB, BC, CD, DE, EF, GH,
HI, IJ, JK, KL, AB', B'C', C'D', D'E', E'F, GH', H'I', I'J'. J'K', and K'L. This is
a simple operation that is readily performed automatically. The relative proportions
in which these cuts are made can vary considerably, for instance in Figure 2, BC is
shown as equal to BJ but it can be equal to or greater than BJ.
[0021] To form a container according to the present invention the portion BCDE is folded
inwards about dotted line BE so that edge CD meets edge JI. Similarly portion B'C'D'E'
is folded inwards about line B'E' so that edge C'D' meets J'I'. Figure 3 shows the
configuration thus achieved. Figure 4 shows the same configuration when viewed from
an angle. Thus it can be clearly seen that in the side wall 3 there are two double-walled
portions, 4,5. Edges JI, DC, D'C' and J'I' are folded inwards to meet at a points
G and L equidistant from side wall portions 4,5 and are fastened by stitching to result
in the configuration shown in plan view in Figure 5 where stitching 6 fastens the
edges. The side wall 3 assumes a slightly rounded configuration leaving gaps 7a, 7b
at G and L between the said side-wall and the newly formed container base. As stated
hereinbefore these gaps can be closed by stitching, glueing, taping or any other means.
[0022] Figure 6 shows the detail of the upper part of a container provided with two lifting
loops. Each of the loops 8a, 8b is threaded through one double walled portion of the
side wall. Sufficient material is provided so that both loops are able to be lifted
by the same hook. The loops may be of any conventional material and conveniently a
length of said webbing is threaded through the double-walled portion, cut off and
the two ends of the webbing are stitched together to form a continuous loop.
[0023] As stated hereinbefore it is preferred to use the container of the present invention
in combination with the inner liner, and is essential when the gaps 7a, 7b have not
been closed. The inner liner may be any suitable liner known in the IBC art, particularly
suitable liners include those of EP-A-80839. Thus the liner is conveniently formed
from a lay-flat tube of impervious plastics film, eg polyethylene of thickness 200
µm by folding operations as shown in Figures 7 to 10, to give a base region of generally
hexagonal configuration QRSTUV in the lay-flat state. The base is formed in conventional
manner by folding corners Y, Z of the bottom of the tube along lines QW, QX and TW,
TX respectively into the lay-flat tube to give the configuration shown in Figure 8.
The upper triangular flap QWT is folded upwards about line QT to give the configuration
of Figure 9. The corners W, X are then folded about lines RS and UV respectively towards
each other to give the hexagonal configuration of Figure 10. This configuration can
then be secured by adhesion.
[0024] As hereinbefore stated the containers of this invention are usually used in conjuction
with the supporting cradle. Suitable cradles are those discclosed in EP-A-80839. In
Figure 11 there is shown an embodiment according to the present invention comprising
a container having double-walled portions 4,5, sealed together at 18, a liner 9, filled
with a particulate material, the container having a double-walled base supported by
a surface 10. The liner 9 is fastened to the container in conventional manner for
example by a line of spots 12a, 12b of a hot melt adhesive. The outer portions of
the container base are supported from surface 10 by a wooden cradle 11, shown in perspective
in Figure 12. The dimensions of the cradle are such that the tines of a forklift truck
can be inserted in the openings 13a, 13b of the cradle.
[0025] The intermediate bulk container is preferably filled whilst positioned on the cradle
as this enables the requisite amount of 'sag' to be achieved, and by using conventional
vibratory filling devices the top of the particulate filling material can be rendered
substantially flat. It may then be advantageous, after filling to substantially eliminate
the air within the liner and to fold down the top of the liner material.
[0026] When the IBC and cradle are lifted, the bulk of the weight is transmitted directly
to the fork-lift truck tines by inter-particle reaction. Only a relatively small
proportion of the load i.e. that corresponding approximately to the hatched area 14
has to be transmitted to the fork-lift tines via tensile forces in the material of
the base of the container. The size of the hatched area 14 for any given intermediate
bulk container/cradle combination will depend on the nature of the particulate material
within the IBC.
[0027] In a particularly beneficial aspect the length of tubular material 1, as partially
depicted in Figure 1, can be cut to form a number of containers without any wastage
of material. This is shown in Figure 13 wherein 15, 16 and 17 represent the material
to form three containers of equal dimensions. Container 15 is cut out as described
in relation to Figure 1; the tubular material is rotated through 90° about the cylindrical
axis and container 16 is cut out (this container 16 is upside down in relation to
container 15, but of course this makes no difference as the cut material is presented
to the folding machine in the desired orientation); the tubular material is again
rotated through 90° and the container 17 is cut out. It can be seen that there is
no wastage of material. In Figure 13, section A₁, A₂, A₃ and A₄ are corresponding
sections in the 4 containers. As can be seen A₁ and A₄ are upside down with respect
to A₁ and A₃. In containers formed in this fashion the reinforcing bands as shown
in 2 on Figure 1 could not be present. Instead they would be positioned as shown partially
in Figure 13.
1. A flexible intermediate bulk container comprising a single piece of tubular material
having a side wall of generally cylindrical configuration, when filled, said side
wall having at least two double walled portions, having single walled portions spaced
between said double walled portioned, at least two of said double walled portions
having a flap extension, said two or more flap extensions being joined to form a base
to said container.
2. A container according to claim 1 wherein there are two diametrically opposed double
walled portions each of which comprises substantially a 90° segment of the cylindrical
side wall and each of which has an integral flap extension.
3. A container according to claim 2 wherein the said two flap extensions are fastened
together at a region equidistant from the respective side walls from which they integrally
extend.
4. A container according to any one of the preceding claims wherein the flap extensions
extend from both the inner and outer walls of each of said double walled portions
so that the base of the container is double walled.
5. A container according to any one of the preceding claims wherein the flap extensions
are fastened or joined together so as to form said base to said container by means
of suitable thread, and/or by the use of a layer, line of adhesive, and/or by the
use of an adhesive tape or patch.
6. A container according to any one of the preceding claims which is provided with
an inner liner.
7. A container according to claim 6, wherein the liner is formed from an impermeable
film of waterproof plastics material.
8. A container according to any one of the preceding claims wherein the tubular material
is a fabric woven from fibres or tapes of a natural or synthetic material or from
a film of plastics material.
9. A container according to any one of the preceding claims wherein a web or rope
is inserted into the double walled portions to provide a means of lifting said bulk
container.
10. A container according to any one of the preceding claims wherein reinforcing threads
are woven into the tubular material to provide one or more reinforcement areas, at
least one such area being in the form of a band running in the warp direction of the
tubular material.