Background Art It is a common practice for goods to be transported to be loaded onto a pallet so that the pallet and goods can be transported as a single unit both by forklift truck and by road, rail or air. Those products which are not easily able to be loaded onto a pallet, for example bulk or powdered materials such as pharmaceuticals or foods such as instant coffee, are contained within a bag or liner formed from a thin sheet of plastics material which is located within a box in order to be protected and supported during transport. The box has, of recent years, been able to be assembled from a number of discreet components (eg a base, a lid and four walls). After the forward voyage, the box is disassembled, the lid and walls stacked onto the base and the disassembled box returned to the sender for subsequent re-use. Similarly, pallets after being emptied are normally stacked together and returned either to the sender or to a pallet pool, when convenient.

Such load bearing transport accessories are typically fabricated from timber (which term is intended to embrace not only natural timber but also timber substitutes such as plywood, particleboard, and like materials fabricated from mixtures of sawdust or similar and glue or resin). There have been many attempts to provide alternative accessories and pallets, in particular, fabricated from plastics and other materials.

Indeed the PCT specifications referred to below disclose several forms of pallet, however, in general such non-timber pallets have not met with widespread commercial acceptance. One of the reasons for this is that the pallet pool operators have a large inventory of existing timber pallets which circulate to and fro.

Particularly in times of economic contraction, there is no demand for new pallets as the existing pool of pallets is adequate for transport of a reduced volume of goods.

However, there are two fundamental disadvantages which apply to such timber transport accessories. The first relates to fumigation, and pest control in general.

Where pallets and boxes, etc are transported over national boundaries, and in particular to relatively isolated countries and/or agricultural producers, such as Australia, which maintain strong quarantine barriers, then it is necessary for the transport accessories to be fumigated along with the goods being transported. The fumigation is aimed at the prevention of introduced pests, diseases, molds, fungi etc, however, since the timber of the accessory is to some extent absorbent and permeable to fumigants such as bromide gas, the fumigant tends to contaminate the transport accessory which, when reused, may in turn contaminate a subsequent load of goods.

For example, electronic products are particularly susceptible to bromide residues contained within timber pallets which have been fumigated. Similarly, in many industries such as the food industry, it is essential that pallets be free of any residual insecticide, fungicide, and the like.

Furthermore, the second problem from which timber transport accessories suffer is that the timber tends to be damaged during use, often not to the extent that the pallet or box needs to be discarded, but generally to an extent where small splits, chipped edges and the like provide a natural harbour for disease, dirt, grime and the like and a source of splinters, wood chips, sawdust and the like. This can lead to subsequent loads being contaminated with dirt, timber splinters, woodchips and so on. Such slightly damaged accessories continue to circulate within a pool until a decision is made by a responsible officer of the pallet pool operator to either discard the accessory or attempt to repair it. Repairs often involve gluing or nailing, and the glue used in this procedure and/or rusted nails can constitute another source of contamination.

Object of the Invention The present applicant seeks to overcome the abovementioned two disadvantages by the provision of an encapsulated transport accessory in which the timber is coated with one or more layers of thermoformable material which provides an hygienic and impervious coating. In addition, such an encapsulated transport accessory is much

more durable than an unencapsulated one and thus enables the capital cost of the pool of pallets or accessories to have its effective working life extended. It is this capital cost which has inhibited the adoption of more modern versions of transport accessories. Thus refurbishment provides an economically attractive alternative for the pool operator and less apparent change for the customers of the pool operator.

Summary of the Invention In accordance with the first aspect of the present invention there is disclosed a method of refurbishing, and increasing the load bearing strength of, a load bearing transport accessory, said method comprising the steps of A. permanently bonding at least one external skin to one side of said accessory by (i) heating a thermoformable sheet intended to form said external skin, (ii) bringing said heated sheet alongside said accessory to overlie said accessory one side, (iii) applying a fluid pressure differential between opposite sides of said accessory and said thermoformable sheet to conform said thermoformable sheet to the shape of said accessory one side and mutually engage said accessory one side, and (iv) maintaining the fluid pressure differential until said thermoformable sheet has cooled where upon tensional forces arise in said thermoformable sheet in all directions, and B. permanently bonding at least one external skin to the opposite side of said accessory by repeating steps (i) - (iv) above in relation to said other accessory side, said two external skins being overlapped to totally permanently encapsulate said accessory.

Where the accessory is a box or like structure able to be assembled and disassembled for forward transport and return passage respectively, each of the components of said assembly is individually encapsulated prior to being assembled.

An encapsulated load bearing transport accessory encapsulated by the above described method and thereby refurbished, is also disclosed.

Brief Description of the Drawings Preferred embodiments of the present invention will now be described with reference to the drawings in which: Fig. 1 is a perspective view of a reusable box used to transport instant coffee, Fig. 2 is a schematic exploded perspective view of the box of Fig. 1, Fig. 3 is an end elevation of the box of Figs. 1 and 2 stacked for the return trip, Fig. 4 is a perspective view of a wooden pallet, and Fig. 5 is an enlarged view of the circled portions of Figs. 2 and 4 showing the encapsulation of the timber.

Detailed Description A method and apparatus for forming structural articles from weak substrates such as polystyrene and cardboard (known as the ARMACEL process), and articles so formed, are disclosed in the applicant's International PCT Patent Application No.

PCT/AU95/00100 entitled"A method and apparatus for forming structural articles" (WO 95/23682), International PCT Patent Application No. PCT/AU96/00541 entitled 'Layered Structural Article" (WO 97/09166) and International PCT Patent Application No. PCT/AU00/00250 (WO 00/59709) -the contents of all three of which are hereby incorporated into the present specification by cross reference. A further, presently unpublished specification is that of International Patent Application No.

PCT/AU2004/000826 which discloses the encapsulation of an interior member which is not at least partially fluid permeable or is perforated to become so. The disclosure of that specification is also hereby incorporated by cross-reference.

These specifications disclose forming structural articles from a shape defining interior member of inherently weak material such as expanded polystyrene and at least one external skin. The basic steps of the method comprise: 1. heating a thermoformable sheet intended to form the external skin, 2. bringing the heated sheet alongside the interior member, 3. applying a fluid pressure differential between opposite surfaces of the interior member and the sheet to conform the sheet to the shape of the interior member and mutually engage same, and

4. maintaining the fluid pressure differential until the sheet has cooled.

Turning now to Fig. 1, there is illustrated a prior art timber box 1 made from plywood which, as illustrated in Fig. 2 is able to be assembled from a base 3, a lid 4, and four side walls 5-8. As seen in Fig. 1 the component parts are latched together by means of metal clips 9. On the forward trip the interior of the box is occupied by a plastic liner within which is located instant coffee.

As seen in Fig. 3, the lid 4 and walls 5-8 are able to be stacked on the base 3 so that the disassembled box 1 can be returned to the original supplier for re-use.

The box 1 is approximately one metre on a side and thus holds approximately one cubic metre of instant coffee which weighs approximately half a tonne. During transport the plywood from which the box 1 is fabricated is subject to various loads and impacts which are liable to splinter the outer layer (s) of plywood. As a consequence, after the box 1 has been re-used a number of times the contents of the box are liable to become contaminated with timber splinters. For many products, such contamination is unacceptable and the entire box must be decommissioned.

The prior art box 1 in accordance with the preferred embodiment of the present invention instead of being decommissioned is refurbished by having each of the base 3, lid 4 and each of the walls 5-8 individually encapsulated. Even the clips 9 have a covering of thermoformable skin over the metal body portions of the latch so that each such portion is more effectively bound to the timber of the box 1.

The plastic layers are in practical terms permanently applied to the timber of the box 1. The plastic encapsulation can only be removed with considerable effort and particles of the box 1 come away with the removed sheets thereby destroying the components of the box 1 for all practical purposes.

Fig. 4 illustrates another conventional timber transport accessory in the form of a timber pallet 11. As is well known goods can be stacked upon the upper surface or

deck of the pallet 11 and strapped thereto for transport. It is well known that forklift truck drivers do not have perfect skills and thus pallets such as pallet 11 are subject to many collisions and impacts with solid objects. These incidents operate to damage the pallet 11, in particular, by splintering the timber from which the pallet 11 is made.

The preferred embodiment of the present invention utilizes the above described prior art process to apply a first thermoformable layer 15 to the accessory 16 from the one side and then a second thermoformable layer 17 to the accessory 16 from the other side so that the layers are overlapped as schematically illustrated in Fig. 5. If desired a bar code device and/or an RFID (radio frequency identification) chip 20 can be encapsulated within either or both of the layers 15,17.

Where it is necessary to provide a pin hole sized opening in the first skin 15 to permit air to be withdrawn from the accessory 16 during application of the second skin 17, that pin hole sized opening can be sealed in a number of ways. These include sealing with silicon rubber, two part epoxy resins, polyurethane"paint"or an adhesive impervious label which can carry data certifying the encapsulation process.

Alternatively, the second skin can be applied without such an opening through the use of the method described in the abovementioned International Patent Application No. PCT/AU2004/000826.

The layers 15,17 are preferably formed from APET, PET, polycarbonate, and other non-permeable chemically resistant thermoformable plastic sheets. Such materials are entirely waterproof, resistant to most chemicals and approved for direct contact with foodstuffs. Thus, in addition to substantially strengthening the accessory 16 because of the tensional forces which arise in all directions in the layers 15,17 as they cool, the encapsulation by the layers 15,17 results in a hygienic accessory which can be repeatedly washed, fumigated etc as required by the most stringent quarantine procedures and without having any deleterious effects on subsequent loads supported by the transport accessory 16. Thus the refurbished box is able to obtain HACCP or FDA approval for use with food or pharmaceuticals respectively. The original box is

not able to meet these standards. Thus an entirely new and expanded range of products are able to be transported in the refurbished box.

In addition, the operable life of the encapsulated accessory 16 is very significantly extended many fold compared to the unencapsulated accessory 16. This has a significant economic benefit since after incurring the relatively low cost of encapsulation, the accessory 16 is able to be used for a long period without the need for any repairs. Thus the capital cost of a pool of encapsulated accessories 16 is only slightly greater than the capital cost of the same size pool of unencapsulated accessories, but the service life of the encapsulated pool is much greater.

Furthermore, the service life can be repeatedly extended by repeating the encapsulation. This is indicated by additional layers 15A, 17A indicated in phantom in Fig. 5. Such additional layers 15A, 17A can be added months or even years after the initial layers 15,17. This is to be contrasted with repairs using prior art processes such as re-nailing, etc which are limited as to application and repeatability and thus provides only a relatively minor extension of service life.

Prior art searches conducted after the priority date have disclosed WO 92/09490 (to which US Patent No. 5,123, 359 corresponds). This specification discloses covering a timber pallet with a removable plastics coating so that the timber components thereof can be disassembled and re-configured if desired. The coating requires application of a top layer, then a bottom layer, and then subsequent formation of a seam between the two layers. Such a removable coating teaches away from the present invention where the plastics encapsulation is permanent. In particular, a removable covering does not bind with the existing component so as to increase its structural strength.

Furthermore, the removable coating not being bonded to the timber components, is liable to split. Such splits harbour moisture, bacteria, fungus, etc and prevent such an arrangement receiving HACCP or FDA approval. A similar situation arises in respect of the continuous seam formed between the two layers. The prior art specification discloses welding which implies that the two plastic layers to be welded cannot be

under tension. Without overlapping as disclosed above it is virtually impossible to guarantee an impervious join at the seam.

The foregoing describes only some embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention. For example, the present invention is not only applicable to"timber"and like cellulose materials including cardboard and particle boards (such as MASONITE (Registered Trade Mark) ) but is also applicable to foam like materials such as expanded polystyrene (EPS) and non-fluid permeable materials such as metals and CORREX, MELAMINE and equivalent materials.

Furthermore, whilst major economic advantages are most quickly obtained by the refurbishment of an existing stock of transport accessories, in other embodiments the present invention is also applicable to virgin materials and articles made therefrom resulting in similar advantages and properties.

The term"comprising" (and its grammatical variations) as used herein is used in the inclusive sense of"having"or"including"and not in the exclusive sense of "consisting only of.