AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Innovation Patent Applicant: AMCOR LIMITED Invention Title: BULK BAG The following statement is a full description of this invention, including the best method for performing it known to us: -2 BULK BAG FIELD OF THE INVENTION 5 The present invention relates to bulk bags that are often used for bulk packaging of products. Bulk bags are also known in the art as Flexible Intermediate Bulk Containers (FIBC). 10 BACKGROUND OF THE INVENTION Typically, bulk bags are understood herein to mean sacks that are used to package large volumes of material, for example and without limitation, the bags may 15 have dimensions ranging up to 1 m wide by 1 m across and by 1 to 2 m in height. Bulk bags can also be used to carry weights of up to 3000 kg or more. Bulk bags can also be open or closed at the top, and can be intended for a single trip, or be reused. Applications for bulk bags 20 include transporting a range of products including food products, industrial products and commodities such as iron ore. Bulk bags are typically made out of 25 polypropylene, of about 200 grams per square metre. Other bulk bags may also have an internal liner that is used within the bag to help keep the product clean and not contaminated from the material of the bag, or for other functional purposes. 30 Whether completely or only partially filled, the bulk bags are lifted from one place to another using a hook or similar lifting device. 35 It is an object of the present invention to provide an alternative and improved bulk bag. 1743364_2 (GHMattera) 28/08/09 - 3 SUMMARY OF THE INVENTION According to the present invention there is provided an bulk bag comprising a base, side walls 5 extending from the base, and a lifting assembly having three or more than three lifting straps, each strap has a different form to the side walls and joined to spatially separated parts of the side walls, and wherein each strap is joined to at least one of the other straps at a lifting 10 point and the bag can be lifted in a stable orientation from the lifting point. Throughout the specification, the phrase "each strap has a different form to the side walls" embraces the 15 lifting straps being made of any suitable material that is different from the manufactured form of the side walls of the bag. For example, the material used to form the straps joined to a bulk bag may be made of polypropylene and the side walls of the bag may also be made of 20 polypropylene, however, the polypropylene of the straps will be in different form of the walls of the bag. For instance, the side walls may comprise a single layer of woven polypropylene material, whereas the straps may comprise multiple layers of the same woven polypropylene 25 material. Similarly, the straps may comprise single or multiple layers of material that are different structurally, or in composition from the side wall of the bag. However in any case, the material used for the lifting straps is not an extension of the material of the 30 side walls of the bulk bag. The straps may also be joined to each other at a single junction or lifting point. The main function of the junction or lifting point is to provide a section for 35 the forks of a forklift truck or a hook to lift the bag. An alternative function is help hold the bag open during filling. 1743364 2 (CHMatters) 28/08/09 In an embodiment, the number of straps is a multiple of two, such as four straps, that are distributed, suitably evenly distributed about the side 5 walls of the bag. In an embodiment, two of the straps are formed by one continuous length of strapping of which opposite ends of the length of strapping are joined to spatially 10 separated parts of the side walls, and the length of strapping is joined at the junction or the lifting point to another one of the straps, or another one of the continuous lengths of strapping. 15 In an embodiment, the bag comprises four straps formed by two continuous lengths of strapping, the ends of each length of strapping being joined to the walls of -the bag at spatially separated parts of the bag. The lengths of strapping may be joined to each other at the lifting 20 point. Alternatively, the lengths of strapping may be unconnected. In an embodiment, the straps are sufficiently stiff so that the straps can be located in a self 25 supporting formation above the bag. In an embodiment, the straps are reinforced to increase their stiffness. The reinforcement can be through the addition of extra material such as additional 30 layers of material of the straps. Alternatively, the straps may be reinforced by the inclusion of resiliently deformable or flexible materials such as a metallic wire or a polymeric strip. 35 The additional reinforcing may only be applied to a section of the straps which are not joined to the side walls of the bag. In other words, a section of the straps 1743364 2 (GHMattera) 28/08/09 -5 extending from the side walls of the straps may have a higher stiffness than sections of the straps joined to the side walls of the bag. Alternatively, the reinforcing may be substantially along the length of the straps. 5 In an embodiment, the junction or lifting point is disposed approximately halfway long the length of strapping between the side walls of the bag. 10 In an embodiment, the junction or lifting point is at an apex of the lifting assembly when the straps are located in self-supporting formation above the bag. The straps may be made of any suitable material 15 including natural materials or synthetic materials. The side walls of the bulk bag can be made of any suitable material which may include natural materials such as cotton. 20 The bulk bag may have any volume, including volumes ranging from 0.5 to 2.5 cubic meters and suitably, volumes ranging from 1.0 to 1.5 cubic meters. 25 In an embodiment the straps are joined to the side walls of the bulk bag over a length greater than 50 mm, preferably greater than 100mm and more preferably greater than 200 mm. 30 In an embodiment the straps are joined to the side wall of the bulk bag for the majority of the height of the side wall of the bulk bag. In an embodiment the lifting assembly further 35 includes a sleeve formation positioned about the junction or the lifting point of the lifting straps. The sleeve formation may be formed by a tubular fabric structure or a 1743364_2 (GHMatters) 28/08/09 -6 flexible sheet that is wrapped about the junction. In an embodiment the sleeve can slide along the straps to assist with the filling of the bulk bags. 5 In another embodiment, the bag includes a top wall having an opening that can be opened and closed as desired. 10 In an embodiment the bag further includes looped straps that can be used for holding an opening of the bag open during filling. Suitably, the looped straps are located near, or at, the corners of the bag. 15 In an embodiment, one or more of the looped straps are configured such that sections of the looped straps are located in overlaying relationship and connected to the side walls of the bag. 20 In another embodiment, one or more of the looped straps may be configured such that sections of the looped straps are fixed to spatially separate areas of the side wall of the bag. For example, the looped straps may be in the form of an inverted U-shaped in which the legs of the 25 U-shaped straddle between adjacent side walls of the bag and, suitably, the legs of the U-shape are closely adjacent to opposite sides of the corners of the bag. In another embodiment the lifting straps the 30 lifting straps and looped straps are connected to at least partially overlapping regions of the side walls. In an alternative embodiment, the looped straps and the lifting straps are joined to separate regions of the side walls of the bag. 35 In an embodiment the bulk bag includes a means for emptying the bags, for example, the base of the bag 1743364_2 (GHMatters) 28/08/09 - 7 may include a plug or open and closeable panel that can be opened for emptying the bag. BRIEF DESCRIPTION OF THE DRAWINGS 5 The present invention will now be described further with reference to the accompanying drawings, of which: Figure 1 illustrates a perspective view of a bulk 10 bag in accordance with a preferred embodiment of the present invention; Figure 2 illustrates a perspective view of a bulk bag in accordance with an alternative embodiment of the present invention; 15 Figure 3 illustrates a perspective view of a bulk bag in accordance with yet another embodiment of the present invention; and Figure 4 illustrates a prior art bulk bag. 20 DETAILED DESCRIPTION Figure 1 illustrates an improved bulk bag 1 according to a preferred embodiment comprising a base 7, four side walls 15a to 15c extending upwardly from the 25 base 7 and a top wall 9. The bag 1 includes four lifting straps 3 which in the embodiment shown in Figure 1 are formed by two lengths of the strapping identified by reference numerals 3a and 3b. The lengths of strapping 3a and 3b are joined at the top and wrapped with another 30 piece of material 4 known as the 'hook material' which locates the lifting point for the forks of a forklift truck or a lifting hook. The hook material may have high wear resistance properties. The bag 1 also includes four looped straps that are identified by reference numerals 2a 35 to 2d. The looped straps 2a to 2d can be used to help hold the bag 1 open during filling. 1743364 2 (GHMattera) 28/08/09 - 8 The looped straps 2a to 2d and the lifting straps 3 extend down at the corners of the bag and overlap for a length of about 60 cm identified by reference numeral 8. The lengths of the strapping 3a and 3b that form the 5 lifting straps 3 extend, at the corners of the bag, below the looped straps 2a to 2d, and are joined directly to the walls of the bag 1 over a longer join area which is labelled by reference numerals 5a and 5b. 10 The looped straps 2a to 2d are joined to the side walls using suitable stitching and sewing methods. Similarly, the lengths of strapping 3a and 3b forming the lifting straps are joined directly to the side walls, or indirectly to the side walls for example, over the looped 15 straps using suitable stitching and sewing methods. Other modes of fastening such as rivets and adhesive may also be employed to join the looped and lifting straps to the walls of the bag. 20 In addition, the top wall 9 of the bag 1 has a round hole or opening 8 for filling the bag 1, and the base 7 has a plug 6 or openable panel which can be removed for emptying the bag 7. 25 The side walls 15a to 15c of the bag 1 may be made of any suitable material and are preferably made of a woven polypropylene material. The straps 3 have a different material form in structure or composition to the side walls 15 to 15c of the bag 1. In addition, the 30 straps 3 may comprise reinforcing such as metallic wires or a polymeric strip for stiffening the straps 3 so that they can be positioned in a self-supporting orientation above the top wall of the bag. The looped straps 2a to 2d for holding the bag during a filling operation, and 35 suitably holding the opening of the bag open may be made of any suitable material including material having the same form of the side walls of the bag or a different form 1743364_2 (GHMatters) 28/08/09 - 9 to the side walls of the bag. The looped straps 2a to 2d may also be made of material that is the same or different to the material of the lifting straps 3. 5 The alternative embodiment of the invention is shown in Figure 2 and has s many elements in common with the embodiment shown in Figure 1. For example the bulk bag body 1, loop straps 2a to 2d located at the corners of the bag 1, the 4 lifting straps 3 formed by two continuous 10 lengths strapping 3a and 3b, the hook material joining the straps 4, the hole 8 in the top wall 9, and the fabric plug 6 that can be removed from the bottom wall 7 of the bag. 15 A feature of difference is that the four lifting straps 3, also formed by two lengths strapping 3a and 3b, are joined to the side walls of the bag 1 as represented by the long join area 11 that extends over the height of the side walls. In the case of the embodiment shown in 20 Figure 1, the lifting straps overlap the looped straps 2a to 2d at the corners of the bag 1 and also extend further downwardly from the looped straps 2 to 2d. However, in the case of the embodiment shown in Figure 2, the lengths of strapping 3a and 3b that form the straps 3are joined to 25 the wall of the bulk at areas 11 that are spaced from the corners of the bag 1. In addition, the bag 1 also includes reinforcing webs 12a and 12b that extends about the junction between the side walls 15a to 15d of the bag 1 and the top wall 9. 30 Figure 3 illustrates yet another alternative embodiment of the present invention which also shares many elements with the embodiments shown in Figures 1 and 2. For example, the bag shown in Figure 3 includes a base 7, 35 side walls 15a to 15c, top wall 9, looped straps 2a to 2d, lifting straps 3 formed by continuous lengths of strapping 3a and 3b, a hook material joining the straps 4, a hole 8 1743364_2 (GHMatters) 28/08/09 - 10 in the top wall 9, and a base 7 which does not include a removable plug or openable panel. The looped straps 2a to 2dare joined to the side walls 15a to 15d at the corners of the bag 1 which have been labelled as areas 10a, 10b 5 and 10c. In contrast, the lengths of the strapping 3a and 3b that form the lifting straps 3 for lifting the bag are joined to the side walls 15a to 15d of the bag intermediate of the corners over a short join 11. 10 Those skilled in the art of the present invention will appreciate that many variations and modifications may be made to the embodiments of the invention without departing from the spirit and scope of the present invention. 15 For example, it is within the scope of the present invention that each lifting strap be separate lengths of the strapping. Alternatively, it is also within the scope of the present invention that two of the 20 lifting straps be provided by a single length of strapping that straddles or arches between sections of the side walls of the bag. Similarly, it is also possible that the three or more of the lifting straps be provided by a single length of strapping and the length of the strapping 25 be wrapped about the outside of the bag as desired. In another example, it is also possible for the lifting straps to be oriented at an angle to the vertical as opposed to an upright orientation as shown in Figures 1 30 to 3. In yet another example, it is possible that looped straps 2a, 2b, 2c and 2d may be positioned about the side wall 15a to 15d of the bag 1 at locations other 35 than at the corners of the bag 1. For instance, the looped straps 2a to 2d may be positioned at locations intermediate the corners of the bag or each looped straps 17433642 (GHMatters) 28/08/09 - 11 may be arranged to straddle the corners of the bag. Figure 4 illustrates a prior art bulk bag including side walls and a base that defined a body 1 for 5 containing material and a lifting assembly in the form of handles that are essentially an extension of the side walls of the bag that are gather and joined directly to each other at the apex of the bag. 10 Advantages of the various embodiments of the present invention are as follows: 1) The lifting straps, whether they each be provided by separate lengths of strapping, or a single length of the 15 strapping that is arranged to provide multiple lifting straps, are advantageous over the prior art structure shown in Figure 4 on the follow basis. a) A problem with using an extension of the side walls of the bag to form a lifting assembly as 20 shown in Figure 4 is that the side wall extensions will partially cover the top of the bag, and can interfere with the filling operation. In contrast, the lifting straps of an embodiment of the invention may be 25 relatively narrow (say 50 mm in width) and the interference of these straps with the filling operation is minimized. b) In addition, dedicated lifting straps mean that the strength requirements and hence the 30 cost of the material used for the side walls of the bulk bag can be reduced. 2) The junction or lifting point formed by joining the lifting straps, whether used by themselves or in 35 conjunction with the sleeve formation or "hook material" has the following advantages over the structure shown in Figure 4. 1743364_2 (GHMatters) 28/08/09 - 12 a) The lifting straps joined together at the lifting point makes lifting of the bulk bags with a single hook or fork a straight forward operation. 5 b) The lifting straps joined together at the lifting point also stiffens the lifting strap assembly so that the straps are self supporting in the sense that the straps can retain an orientation ready for engagement 10 with a hook or fork on their own accord. However preferably, the straps of the lifting assembly is not too stiff so as to prevent the straps from being moved to one side to reduce their interference to the filling operation of 15 the bag. 3) The lifting straps are joined to the side walls of the bulk bag over a length of the straps. This enhances the performance of the bag compared to the bag shown in 20 Figure 4 in the following manner. a) Joining dedicated lifting straps to the side walls of the bag reduces point stress on the wall so of the bag and in turn reduces the chance of breakage where the long straps join 25 the bulk bag. b) The dedicated lifting straps also allows the walls of the bag to be constructed from lighter weight material than previously thought possible. The reason for this is that 30 the walls need not be of sufficient weight so that the walls can also be transformed into handles of a lifting assembly as is the case with bag shown in Figure 4. c) The dedicated lifting straps stiffens the 35 overall structure of the bag, ensuring that the bag is more likely to form a cubic or rectangular-cubic shape when filled. This will 1743364_2 (GHMatters) 28/08/09 - 13 assist with storage, transportation, and can assist with emptying of these bags when these bags are emptied from the bottom of these bags. 5 4) Some embodiments of this invention feature pairs of straps that are formed by a continuously length of the strapping. These embodiments are an improvement on other bags known in this art in which the straps are 10 formed from the side wall of the bag as shown in Figure 4. In particular, the continuous length of strapping that form a pair of lifting straps has the advantage that there is no risk of the join between discrete straps failing under load, which can lead to product 15 damage, or harm to objects or people underneath the bulk bag when the straps fail. 5) In addition to the lifting straps, embodiments of the invention also include looped straps that can be used 20 for holding the bag in an opening position during filling of the bag. The looped straps can be made of any type of material including materials that are different to the material of the lifting straps. 25 In the claims in relation to this invention and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in 30 an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 1743364 2 (GHMatters) 28/08/09