AU2003203986B2 - Plastic bag - Google Patents

Description

Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT (ORIGINAL) Name of Applicant: PETER LAWTON Actual Inventor(s): PETER LAWTON Address for Service: SANDERCOCK & COWIE & ASSOCIATES 69 ROBINSON STREET DANDENONG VIC 3175 Invention Title: PLASTIC BAG Details of Associated Provisional Application(s): No(s): Australian Provisional Application No. PS2152 Filed: 2 "d May, 2002 The following statement is a full description of this invention, including the best method of performing it known to me: S I - - la TITLE: PLASTIC BAG FIELD OF THE INVENTION 5 This invention concerns plastic bags for wrapping the root balls of shrubs and trees. BACKGROUND OF THE INVENTION 10 In a plant propagation nursery, large areas are given over to the propagation of young trees from the two leaf stage to the four metre stage. Recent work has shown that -2 managing root tip development by improved pot construction can improve rates of growth. The use of pots and containers having characteristics which encourage the natural root building stages of a young tree, produce strong growth in tree height, accompanied by strong growth in stem taper. I refer to this root building mode as air root 5 pruning. The type of container which produced the enhanced root growth is too costly to sell with the tree when the tree is shipped to the plantation, park or other destination. The tree must be shipped in a much cheaper container which does not damage the established root 10 ball, which retains moisture and growing medium and which presents minimal disposal problems. A conventional plastic bag or wrap will fulfill these requirements, but allows the root ball to fall apart, shedding the particulate growth medium. The use of knockdown containers made from vacuum moulded perforated sheets sitting on moulded perforated disks available under the trade mark ROCKETPOT generates a compact root 15 ball with a more cohesive structure. If this ball breaks up as it is being harvested from the ROCKETPOT container to the shipping bag, the tree is harmed and its subsequent growth is impaired. SUMMARY OF THE INVENTION 20 This invention provides a bag for wrapping the root ball of a shrub or tree, the bag being made from blown tube with one end closed by a transverse weld, wherein the side wall has a dart which reduces the circumference of the bag from the open end towards the closed end. 25 The bag may be a satchel with gussets enabling the bag to be rectangular in plan and to be stacked flat into a pile awaiting use or in continuous rolls of 'tear off bags. The transverse seal which closes the end causes the bag to open such that the seal extends across the diameter of the generally cylindrical root ball and the bottom portion extends 30 across the root ball base, leaving the mid section of the bag to accommodate the cylindrical root ball itself. Preferably the dart is inserted in this part of the side wall of the bag.

-3 Preferably the mouth of the bag is excluded from the dart in order to give it the full bag circumference. This permits the packer's hand to slip between the entering root ball and the mouth of the bag. 5 The term "dart" includes a cross-section reducing seam which runs into the side wall like a tailor's dart or which stops short of the side wall. Functional equivalents, such as a series of abbreviated transverse welds which extend further from the side wall where they begin as they progress down the side wall, are included in the term. 10 Typically, the degree of taper may be 3-12'. The length of the dart may be 200-350mm. Handle Assembly Another apparatus aspect of the invention provides a handle assembly for the plant bag 15 described above comprising a pair of interfitting rings capable of trapping the mouth of bag, one being a lifting ring with a hand grip extension, the other being a locking ring which provides a reaction surface for the lifting ring. The lifting ring may be split in order to facilitate its insertion within the locking ring. 20 BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the invention is now described with reference to the accompanying drawings, in which: 25 Figure 1 is a plan of the bag. Figure 2 is a view through the open mouth of the bag. 30 Figure 3 is a side view of the bag shown in Figure 4. Figure 4 is a side view of the bag containing the root ball of a young tree.

-4 Figure 5 is a sectional perspective of the bag handle. Figure 6 is a perspective of the lifting ring of Figure 5. 5 Figure 7 is a perspective of the locking ring of Figure 5. DETAILED DESCRIPTION WITH RESPECT TO THE DRAWINGS An extruder supplied with an air stream blows a 1 00p2 thick polyethylene tube. The tube 10 passes through guides which introduce the satchel configuration. In another machine, a transverse weld is inserted with a tear off perforation at 660mm intervals. This sequence is standard procedure in the art and makes a 660 x 330mm satchel. In the method of this invention, and referring now to the drawings, the bags are fed to a perforator which simultaneously removes a set of 10mm circles 2 from the gussets 4 creating eight holes 15 in the bag. The first set of holes are 90mm from the seal 10. The second set are 180mm from the seal 10. The level of the first set of holes indicate the end of the inclined weld 12. The weld runs along the gusset fold 14 to 100mm from the bag mouth 16. The inclined weld 12 is 340mm long. The bags circumference at A is 1240mm and at B is 1200mm. When the ROCKETPOT container is dismantled as a disk and separate sleeve 20 from the root ball, the root ball has a circumference of 1240mm. The tree is laid over through 90 so that the curved face of the root ball lies on the ground. The open end of the bag is covered up to the circular base of the root ball. The bag is eased into the mouth bag by rolling the root ball over the ground. Once inserted the tree is returned to vertical as the bag is held by its mouth causing the root ball to slide downwards into the bag 25 under gravity. As it enters the bag the ball undergoes slight compression as it moves towards the closed end of the bag. The trapped air escapes through the holes. In another method, the bag is placed in a bin the same size as the root ball and the mouth of the bag is folded over the lip of the bin. The root ball is then lowered into the bag and 30 is a sufficiently loose fit in the bin to be lifted out together with the bag. The bagged tree is placed on the pallet or a cage for shipping. Referring now to Figures 5-7, an L-section H.D. polyethylene split lifting ring 18 has a circumferential bead 20 on which is seated a moulded locking ring 22. The locking ring is a close fit on the joined lifting ring in order to trap the mouth 16 of the bag. The inturned flange 18 of the lifting ring is about 40mm deep so as to provide a grip for the hand. 5 In use, the locking ring is placed underneath the bag and pulled up to a level well above the soil level 24 of the root ball. The lifting ring is opened, passed around the tree stem and joined by a locking tongue (not shown). The joined lifting ring is forced inside the mouth of the bag. The locking ring is passed outside the mouth of the bag until it locks. 10 The rings trap the film and the excess protruding film is trimmed off with a knife. I have found the advantages of the above embodiment to be: 1. Reliable compaction of the root ball. 15 2. The insertion of the dart can be formed simultaneously with the transverse weld and the perforation. 3. Easy fitment to the root ball, even when there are slight differences in root ball 20 diameter. 4. The handle assembly offers 3600 grip. It is to be understood that the word "comprising" as used throughout the specification is 25 to be interpreted in its inclusive form, ie. use of the word "comprising" does not exclude the addition of other elements. It is to be understood that various modifications of and/or additions to the invention can be made without departing from the basic nature of the invention. These modifications 30 and/or additions are therefore considered to fall within the scope of the invention.

Claims (8)

1. A bag for wrapping the root ball of a shrub or tree, the bag being made from blown tube with one end closed by a transverse weld, wherein the side wall has 5 a dart which reduces the circumference of the bag from the open end towards the closed end.

2. A bag as claimed in Claim 1, wherein the bag is a satchel with gussets. 10

3. A bag as claimed in Claim 1 or 2, wherein the dart is located in the mid-section of the bag.

4. A bag as claimed in Claim 1, 2 or 3, wherein the mouth of the bag is excluded from the dart in order to admit the users hand between the root ball and the mouth 15 of the bag.

5. A bag as claimed in any one of Claims 1-4, wherein the degree of taper of the dart is 3-12'. 20

6. A bag as claimed in any one of Claims 1-5, wherein the dart may be 200-350mm long.

7. A bag as claimed in any one of Claims 1-6, wherein the bag is a blown plastic bag and the dart is a weld joining two zones of the bag side wall. 25

8. A bag substantially as herein described with reference to and as illustrated in the accompanying drawings. Dated this 2 "d day of May, 2003. 30 SANDERCOCK & COWIE PATENT ATTORNEYS FOR PETER LAWTON