NZ195617A - Woolpack formed from non-woven sheet material.top cover flaps defined by terminally reinforced slits - Google Patents

Description

1 1 95) Priority Date(s): P. J. iiirJl3. ?■ Complete Specification Filed: Class: J3&5Q3.9//.Q....

Publication Date: .. JJ.DEC.I985! P.O. Journal, No: . ........

NEW ZEALAND PATENTS ACT, 1953 Date: COMPLETE SPECIFICATION -"WOOLPACK" BOSBY NOMINEES PTY LTD, a company incorporated under the laws of the State of Victoria, of 1 Palmerston Crescent, South Melbourne, in the State of Victoria, Commonwealth of Australia hereby declare the invention for which £x/ we pray that a patent may be granted to Kf£/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - Followed by page la 1956 1 7 lc\ "WOOLPACK" The present invention relates generally to the packaging of wool or fleece and more particularly to an improved woo]pack.

For many years, the handling, storage and' 5 transport of raw wool has been based upon the standard wool bale, which is of substantially rectangular form and has the approximate dimensions of 75 X 75 X 9 8cms. The weight of compressed wool forming the bale is typically in the range 14 0 to 210kgms. The traditional 10 enclosure for the wool bale is a bag or sack of a jute material and indeed a subs tantial .proportion of commercial wool packs continue to be of this material. However, in recent times jute has become less readily available and the relative cost of jute wool-15 packs has increased appreciably. This has been of some concern to an industry which must minimise, and where possible reduce, its costs, to maintain its produces competitiveness with respect to synthetic fibres.

The long standing use of jute as the 20 primary constituent of woolpacks had arisen from its proven adaptability to the various requirements of the wool handling sequence. Wool bales are generally formed and packaged in the shearing shed by means 19561 2 of a wool press of variable sophistication. Typically, the loose pack is placed in a rectangular form:at this point some degree of shape is desirable in the pack so that it can free stand with minimum support. Wool 5 is fed through the open mouth of the pack in predetermined quantities, which are compressed in turn by the press. Once the pack is full, the mouth is closed and the stakes which have been preventing expansion of the wool within the bale are withdrawn. The inherent 10 resilience of the wool tends to cause it to expand and accordingly the packmust be sufficiently strong to hold the wool in its bale. Moreover, the expansion tendency is substantially stronger in the lengthwise direction of the bale, that is,parallel to the original 15 direction of compression. .

During subsequent handling, transport and storage of the bale, the enclosing pack must be able to withstand relatively rough treatment, since it is generally moved around by the use of hooks which are 20 sunk into the wall of the pack. Furthermore, the pack must not fail when breached for extraction of a core sample and grab sample , as required for modern auctioning techniques. Finally, the-pack must not fail during the so-called dumping process in which the bale 25 is further compressed to either one half or one third its original size for assembly into a medium or high density bale, respectively, for containerized shipment.

In an effort to meet these requirements in a material more cheaply and readily available than jute, 30 wool bale packs have been manufactured from woven synthetic fabrics such as woven polypropylene , woven nylon, and woven high'density polyethylene. However, such materials have been found to I |956\7 3 contaminate the wool with minute fibres and particles which are highlighted in the final woollen fabric as dyeing faults. A secondary disadvantage is the need for lengthwise seams in the pack assembly. Suggestions 5 that at least the fibrillation contamination problem might be overcome by substituting a plastics sheet material such as polyethylene film have been discounted because light gauge polyethylene would stretch and break under the expanding resilient force of the compressed 10 wool in the bale, while such material of sufficiently heavy gauge to overcome this force would not be commercially viable and would be difficult to handle.

Australian Patent specification 29085/30 discloses a woolpack formed of at least two laminations of reinforced 15 paper bonded by a flexible adhesive. Supplementary reinforcements, such as tapes, cords, strips or slips of reinforced paper are attached to the pack and embodied in the adhesive films between adjacent sheets of paper. These reinforcements are said to be disposed 20 vertically of the pack so that they will take a portion of the bursting stress, which is greatest in the direction of the pack's height.

Australian Patent specification 2508/31 proposes a woolpack of sheepskins, with one or more optionally sewn 25 strips of canvas passed vertically around the pack.

It is therefore an object of this invention to provide an improved woolpack which will meet the handling requirements of the industry but permits the use of a practicable readily available constituent 30 material not liable to contaminate the wool.

The invention accordingly provides a woolpack comprising a bag of a non-woven sheet material closed at one end by seams disposed to shape a broadly rectangular bottom for the bag when 35 expanded, wherein the bag further includes multiple 195617 * 4 slits from the other end of the bag defining flaps able to be overlaid to close said other end, said slits being provided at their respective inner ends with reinforcing means to prevent the slits from running when the bag 5 encloses a bale of compressed wool.

Desirably, said non-woven sheet material is heat sealable, has high impact strength and low slip, and exhibits high resistance to tear propagation. The preferred non-woven sheet material for the bag is a 10 polyolefin film, possibly a pluaral layered film such as a co-extruded film. Polyethylene film is presently preferred. It is particularly advantageous to employ low density polyethylene produced in continuous tubular form, for example by the presently conventional blown-15 bubble extrusion process. The bag thus formed is free of lengthwise seams and specially lends itself to closure by the formation of said seams.

The preferred configuration of said seams for optimum strength and stress distribution comprises linear seals, most preferably four mitre seals, such as heat applied seals, extending from a centre region of said broadly rectangular bottom to outer extremities substantially defining the corners of a rectangle and thus of said rectangular bottom. For 25 additional strength, the bottom may be wholly or partially plural layered and a fifth end seal may extend substantially wholly across said bottom. Where this seal is a heat applied seal, it is preferably skirt-less in order to enhance level seating by the bag 30 bottom.

Advantageously, the bag further includes one or more reinforcing straps passed about opposite sides and the bottom of the bag. Preferably such straps are adhered continuously to the bag, but not adhered to the flap.?. 195617 Where two or more such straps are provided, they are preferably arranged in respective parallel planes substantially normal to the sides of the bag to which they are adhered. In the preferred 5 case where the bag is formed of low density polyethylene, at least two such straps are presently considered essential if failure of the bag as a woolpack is to be prevented.

Said reinforcing means preferably comprise 10 respective substantially circular or elliptical apertures at which the slits terminates.The rim of the aperture is advantageously beaded for enhanced strength.

Said bag is preferably punctured by a multiplicity of breather holes to allow escape of air 15 from the interior of the bag during the aforementioned dumping process. These holes may also be of advantage in allowing baled wet wool to breathe.

The invention will be further described by way of example, only with reference to the accompanying drawings, in which 30 Figure 1 is a perspective view from above of a woolpack in accordance with the invention, shown in the position in which it is placed in the wool press ready for charging with wool; 17 SEP 1984 1956 Figure 2 is a further perspective view but more clearly showing the bottom of the pack; Figure 3 is a cross-section on the line 3 - 3 in Figure 2 showing portion of the bottom of the 5 pack; Figure 4 is an enlarged view of a corner of the pack as seen in Figure 1, but with the flaps lifted up almost into edge contact; Figure 5 shows a flattened extruded 10 polyethylene tubular blank partially formed into a pack according to the invention; and Figures 6A and 6B are respective scale-matched cross-sections through one end of the flattened blank depicted in Figure 5, respectively prior 15 to and after forming of the transverse end seal.

The illustrated woolpack 10 includes a tubular bag 12 formed from a blank 12' (Figure 5) which has been cut from an extruded tube of low density polyethylene film typically produced by the blown-bubble 20 extrusion process.

Bag 12 is closed at one end by a: closure configuration 14 which includes multiple linear heat seals 16a-d, 18. The other end of the bag is open but is provided with four parallel, substantially equicircumferentially 25 spaced lengthwise slits 20 which are reinforced at their inner ends by reinforcement formations comprising circular apertures 22. slits 20 may merely be. ...cuts in thp bag or, if desired, may be the result of cutting narrow strips from the bag.

The polyethylene film from which bag 12 is formed is of a gauge between 75 and 400pm, preferably between 100 and 300ym. The melt flow index of the polyethylene is desirably between 0.1 and 1.5 and its relative density in the region of .92. The material 35 conveniently conforms with Australian standard ASK 1326. 195617 7 Closure configuration 14 is best appreciated by reference to Figure 5/ During the early stages of manufacture of pack 10, the tubular polyethylene blank 12' is flattened in the manner shown so that outer flats 12a, 12b of the tube act to sandwich therebetween folds of substantially similar width which almost contact along a longitudinal centre line,of the flattened blank. The half segments 12c, 12d of the folds are then separated by spacers and four diagonal linear heat seals 16a-d (only two visible in Figure 5) are applied as shown to seal each flat 12a, 12b to the underlying fold segments 12c, 12d (Figure 6A) . The spacers are removed and the aligned ends of the flats and folds sealed together by a transverse heat seal 18. (Figure . the seals 16a - d form mitre seals which shape a generally rectangular,partially multiple layered bottom for the bag, wherein the corners of the bottom sub-20 stantially coincide with the outer extremities of the seals (Figure 2) . It will be seen that the bag has thus been mitre sealed in a partially plural layered formation to determine a block bottom for the bag, and that associated longitudinal folds 21 extend upwardly 25 from the ends of the mitre seals to impart a generally rectangular shape to the tubular blank. The seals define four double layer triangular panels 13 which in pairs underly larger single thickness triangular panels 15 that each form between two mitre seals and a fold 30 line 17. Fold lines 17 appear at opposite side edges of the blank as it is expanded. Between panels 13 are respective single thickness panels 15a bounded by the mitre seals and by the other side edge folds 17a. 6B).

When the resultant bag is now opened out \ 195617 8 The transverse end seal 18 is preferably skirtless and it is found that such a heat seal imparts additional strength to the closure configuration: this is thought to arise from rapid contraction and lateral 5 bulging of the sealfas demonstrated by comparison of Figures 6A and 6B,after application of a heat bar to effect the seal.

The illustrated bottom configuration comprising seams or multiple closure elements in the form, in this instance, of linear heat seals, has been found especially effective in withstanding the substantial longitudinal expansion forces of a contained wool bale by providing a plural layer strengthened bottom in which the internally derived stresses are 15 distributed among the multiple seals. The realization that the closure configuration in question is especially suitable for a woolpack has been an important element in the successful development of the inventive pack. 2o Slits 20 are effective to determine flaps 2 4 which are able to be overlaid to close the upper end of the bag. To this end, slits 20 are disposed in alignment with the corners defined by. the extremities of mitre seals 16a-d. The dimensions of flaps 24 are 25 dependent upon the method by which the bag is closed after formation of the bale therein. The lengths of the slits should be chosen such that the filled closed woolpack fully expanded and is of parallelepiped form of dimensions of the order of 75 X 75 cm at the 30 bottom and 9 8 cms top to bottom, in accordance with the size of the standard wool bale of the Australian Wool Corporation. Reinforcement apertures 22 are about 5cms in diameter and are themselves reinforced about their rims by heat induced beads -2'6_ 1956 1 '9 The provision of the beaded reinforcement apertures 22 resolves an initial serious difficulty with the use of material such as polyethylene in that they successfully prevent running of the slits 20 when the bag 12 encloses 5 a bale of wool under expansion pressure.

The use of polyethylene of the gauge earlier foreshadowed entails a requirement for effective reinforcement of the bag 12 against stretch under the expansion forces of wool compressed therein. To this 10 end, bag 12 is encircled by a pair of load supporting straps 28, 2 9 which extend about the bag in respective planes parallel to opposed sides of the bag and which are continuously adhered to the bag along the other sides and bottom thereof. The straps may comprise, for 15 example, polyester bands. They remain unattached to the flaps and their ends carry suitable co-operating buckle means 30 for the firm closure of the straps once the bag is filled with compressed wool. The straps may be intermittently adhered to the bag, but continuous, 20 sustained adhesion is preferred, so that the straps remain in place during the dumping process. It is thought that the straps should be equidistant from the upright corners of bag 12 and from the vertical centre of the sides to which they are attached.

Bag 12 is punctuated in a substantially uniform manner by a multiplicity of small breather holes 32 which allow air, vapour or gases to escape from the interior of the bag if it is subjected to a dumping process and may assist in ventilating wet wool.

Prior to use, the pack 10 is stored in a flattened condition. In use, bag 12 is opened up and placed in the wool press in the conventional manner, being substantially free standing by virtue of the mitre seals shaping a bottom of the generally rectangular 1956 form required. Flaps 24 and straps 28, 29 are laid outwardly in non-obtrusive positions and the bag, which will essentially be in a condition similar to that shown in Figures 1 and 2, is ready to receive 5 successive charges of compressed wool. Transverse stakes passed through the bag prevent expansion of the wool during the filling state. When the bale is complete, the flaps 24 are overlaid and the bag closed to form a parallelepiped package of wool typically of mass in 10 the range 140 to 210 kgms and of the aforementioned dimensions. The straps 28, 29 are likewise firmly buckled and the stakes removed. The inherent resilience of the wool tightens the straps as they, the mitre seal block bottom and the closed top take up 15 the load arising from the expanding wool. As indicated, this load is thought to be predominantly against the top and bottom of the bag.

Claims (21)

195617 WHAT-#V;E, CLA'M IS: 11

1. A woolpack comprising a bag of a non-woven sheet material closed at one end by seams disposed to shape a broadly rectangular bottom for the bag when expanded, wherein the bag further includes multiple slits from the other end of the bag defining flaps able to be overlaid to close said other end, said slits being provided at their respective inner ends with reinforcing means to prevent the slits from running when the bag encloses a bale of compressed wool.

2. A woolpack according to claim 1 wherein said non-woven sheet material is heat sealable, has high . impact strength and low slip, and exhibits high resistance to tear propagation.

3. A woolpack according to claim 1 or claim 2 wherein said non-woven sheet material is a polyolefin film.

4. A woolpack according to claim 3 wherein said non-woven sheet material is or includes a polyethylene film.

5. A woolpack according to any one of claims 1 to 4 wherein said bag is free of lengthwise seams.

6. A woolpack according to claim 5 wherein the bag is a tube of low density polyethylene produced by the blown-bubble extrusion process. 1 e.- £ ft 12

7. A woolpack according to any preceding claim, wherein said closure elements comprise linear seals.

8. A woolpack according to claim 7 wherein said multiple closure elements comprise four mitre seals extending from a centre region of said broadly rectangular bottom to outer extremities substantially defining the corners of a rectangle and thus of said rectangular bottom.

9. A woolpack according to claim 8 further comprising a fifth end seal which extends substantially wholly across said bottom.

10. A woolpack according to claim 9 wherein the sheet material is heat-sealable, and the fifth seal is a skirtless heat seal.

11. A woolpack according to any preceding claim wherein said bottom is wholly or partially plural layered.

12. A woolpack according to any preceding claim wherein the bag further includes one or more reinforcing straps passed about and adhered to opposite sides and the bottom of the bag.

13. A woolpack according to claim 12 wherein the adhesion of the strap(s) to the sides and bottom of the bag is continuous. 195617 13

14. A woolpack according to claim 12 or 13 wherein two of said straps are provided, arranged, when the bag is expanded, in respective parallel planes substantially normal to the sides of the bag to which they are adhered.

15. A woolpack according to claim 12, 13 or 14 wherein each said strap comprises a polyester band strap.

16. A woolpack according to any preceding claim wherein said reinforcing means comprise respective substantially circular or elliptical apertures at which the slits terminate.

17. A woolpack according to claim 16 wherein the rim of each aperture is beaded for enhanced strength.

18. A woolpack according to any preceding claim wherein said bag is punctured by a multiplicity of breather holes. 195617 14

19. A packaged woolbale comprising compressed wool enclosed in a woolpack according to any preceding claim, which bale is substantially of parallelepiped form.

20. A packaged woolbale according to claim 19 of mass 140 to 210 kgms and dimensions approximately 75 x 75 x 98 cms.

21. A woolpack substantially as hereinbefore described with reference to the accompanying drawings. . f>J .Q'.c-.vn .. 8y-feis£heir auttarise^ Agents 17SEPJ984