EP0876284A1

EP0876284A1 - Lightweight plastic pallet

Info

Publication number: EP0876284A1
Application number: EP97907490A
Authority: EP
Inventors: Oddbjorn Gronnevik; Helge Grande; Rolf KÖTTERHEINRICH
Original assignee: Borealis AS
Current assignee: Borealis Technology Oy
Priority date: 1996-01-11
Filing date: 1997-01-10
Publication date: 1998-11-11
Also published as: CA2242721A1; WO1997025250A1; AU1948297A; CN1208386A; NO960910D0; AU707915B2; NO960910L

Abstract

A lightweight pallet made of a thermoplastic material, having a deck and integrated sheet legs underneath the deck along its longitudinal, transverse, or both sides. The pallet being fabricated by thermoforming an extruded plastic parison having a monolayer or multilayer structure into one predominantly flat article and bringing the side parts of the article into a position perpendicular to the pallet deck and affixing the sheet legs in that position. The pallet may further be provided with appropriately designed runners.

Description

LIGHTWEIGHT PLASTIC PALLET FIELD OF INVENTION

This invention relates to a lightweight plastic 5 pallet, in particular a pallet having integrated sheet-like pallet legs or runners.

PRIOR ART

Pallets are included as a part of the goods that are

10 to be transported and/or stored on them, and therefore it is important for the pallet to be lightweight, but strong and rigid at the same time. Plastic pallets have the advantages over wooden pallets that they are lightweight, that they do not absorb moisture, and that they can be cleaned/disinfected, i5 which is decisive in fields where hygiene is important, e.g., in the food industry.

European Patent No. EP-0 400 640 discloses a plastic pallet that is assembled from a top deck and a bottom deck with runners, or from a deck and runners. The components are

2o formed with legs that are inserted into one another during assembly. Mechanical fasteners in the form of metal plates having die-cut notches, nails or the like can be employed to ensure that the components hold together.

Swiss Patent No. CH-685549 A5 discloses a plastic

25 pallet that is injection molded in two components, namely, a top deck and a bottom deck comprising posts and runners. The top deck and the bottom deck, both having reinforcing ribs, are butt-welded together so that the side edges and ribs are welded together against one another. Directly within all four

30 side edges and along the center line longitudinally there are in the ribs semicircular openings into which steel pipes or flat rods can be jammed for mechanical reinforcement of the pallet. The plastic pallet is preferably fabricated from poly¬ ethylene. 5 Swedish Patent SE 501,539 relates to an injection molded pallet runner, preferably comprising two or three sepa¬ rate, hollow, closed channels along its entire length. The runner is lightweight, while rigid. It can be fastened by its top to suitable posts, which again are fastened to the bottom of a pallet deck.

International Application WO 93/18906 relates to a blow-mold device for producing one-piece, externally smooth, double-walled plastic plates with internal spaces formed dur- ing blow-molding. The high bending resistance of the manufac¬ tured plate makes it suitable for making plastic pallets.

Prior art plastic pallets are fabricated by injection molding of components that are then joined together. The com¬ ponents will typically have reinforcing ribs at required places in order to attain a lightweight rigid construction. In the injection molding of such large objects, very large and expensive injection molding tools are used that require large injection molding machines having great clamping forces. Con¬ sequently, it would be desirable to be able to make plastic pallets by a simpler and more economical method. A possible means of attaining this object is to thermofor the pallet from an extruded plastic sheet or from a parison, like the blow molding of large objects such as barrels, gasoline tanks, etc. To attain a lightweight and rigid construction it is often desirable to employ a coextruded multilayer structure where one of the layers is at least partially foamed. For in¬ stance, US Patent No. 4,874,649 discloses a method for the blow molding of a coextruded parison comprising at least two layers, one of which, perhaps more, is at least partially foamed.

Applicant's contemporary Norwegian patent application NO-A-960128, the disclosure of which is hereby incorporated by reference, relates to a pallet manufactured by thermoforming a parison of the type disclosed in US Patent 4,874,649. This parison is formed into a pallet deck and spacer and runner components, which are assembled in a subsequent separate oper¬ ation. Thus, a lightweight, however strong and rigid construc¬ tion, is attained. The pallet may be reinforced by introducing rigid sections into cavities formed between the pallet deck and spacers.

For many purposes especially lightweight pallets, often of a smaller size than standard normal sized pallets, are desired. It has now been found that it is possible to fab¬ ricate a lightweight pallet having pallet legs and runners of a simplified construction compared with the pallet disclosed in Applicant's above mentioned patent application.

The pallet's smooth and even surface makes it very simple and easy to clean and disinfect. The pallet is there- fore especially well suited for use in the food industry and allied industries. The pallet has a great strength/weight ratio because of its design. As a result, it is well suited for purposes where low weight is important, e.g. in air freight, and where manual handling of pallets occur frequent- ly.

SUMMARY OF THE INVENTION

The present invention provides a pallet made of a thermoplastic material, the pallet comprising a deck and legs disposed underneath the deck. The pallet deck has top and bot¬ tom surfaces and a set of opposed longitudinal sides and a set of opposed transverse sides, and sheet legs integrated with the deck and disposed along at least one of said set of sides of the pallet deck. The pallet is fabricated by thermoforming an extruded thermoplastic parison having a monolayer or multi¬ layer structure into one predominantly flat article having a set of opposed longitudinal sides and a set of opposed trans¬ verse sides, and then bending at least one of said set of sides of the article into a position perpendicular to the main part thereof to form the sheet legs, and affixing the sheet legs into said position.

The invention also provides a pallet, made of a thermoplastic material, comprising a deck and at least two runners disposed underneath said deck. The pallet deck, having top and bottom surfaces, and the runners, being in the shape of a cross member having a upward-facing runner post in each end thereof, are fastened by a top surface of said runner posts to the bottom of the pallet deck. The pallet deck is produced by thermoforming an extruded plastic parison having a monolayer or multilayer structure into one predominantly flat article. The runners are produced separately by thermoforming an extruded parison identical to the one used in the produc¬ tion of said pallet deck into a predominantly flat article and bending the end parts of this article into a position perpen- dicular to the main part thereof to obtain the runners having upward-facing posts.

BRIEF DESCRIPTION OF THE DRAWINGS 5 Fig. 1 is a perspective sketch of a fabricated pallet comprising sheet legs and a leg structure consisting of block- shaped posts located in the center longtitudinally.

Fig. 2 indicates the principle of constructing the sheet legs. o Figs. 3 and 4 are sectional views showing alternative designs of the plate-shaped legs.

Fig. 5 is a sectional view through the center long¬ itudinally of a pallet having legs consisting of deep-drawn posts. s Fig. 6 is a sectional view through a block-shaped pallet leg of an alternative design.

Fig. 7 is a perspective sketch of a pallet deck and runner components prior to joining together.

Fig. 8 is a sectional view through a part of the o pallet deck and spacer and runner components fastened to the bottom of the deck along its center longitudinally.

Fig. 9 is a top view of a pallet where the pallet deck has raised sections.

Fig. 10 is a side view of the pallet in Fig. 9. 5

DETAILED DESCRIPTION OF THE INVENTION

The present pallet is manufactured by a process that comprises a number of steps. The first step consists in extru¬ ding a parison, preferably as disclosed in the above mentioned o US 4,874,649. The extrudate can have various wall thicknesses around its periphery, obtained by the use of an extrusion die of a suitable configuration. Thus, different parts of the pal¬ let can be given different wall thicknesses. The extruded par¬ ison is flattened, and, when still hot, shaped in a mold to a 5 substantially flat article. Parts of the article can be given a desired shape, e.g. profiled structures, deep-drawn posts, etc. by utilizing combinations of compressed air and vacuum. When the parison is laid flat, those parts of the insides forced into contact with each other will become welded to- gether and form a double sheet. The principles of extrusion and forming are well known to persons skilled in the art.

In its simplest embodiment the parison consists of a homogeneous (solid) material. In order to make the extruded structure lighter, the parison can be coextruded with several layers, where at least one layer is at least partially foamed. Present-day coextrusion technology permits a number of options for the shape and structure of the parison. For instance, the extruded structure can in one specific embodiment of the in- vention consist of a foamed plastic layer having a solid skin on just one side thereof. The foamed layer should preferably have a closed-cell structure, however, this is not an obliga¬ tory feature. In practice, a foam having a density of down to about 100 kg/in³ can prove useful. The skin will form the pal- let's outsides, so that a wear-resistant and easy-to-clean surface is attained.

In another specific embodiment of the invention, the extruded structure comprises a foamed layer having a solid skin on both sides, or optionally multiples of such a multi- layer structure. Such a sandwich structure will, it is common knowledge, have high torsional rigidity and produce a light¬ weight construction. The foam layer typically comprises about 70% of the sheet structure's thickness, and each skin layer about 15%, more preferably about 80% and about 10%, respecti- vely. When the foam has a closed-cell structure, in some cases it can even constitute the entire wall thickness. The foam can have a density within the range of from the density of a solid material down to as far as it is practicable possible to pro¬ duce a stable polymer foam. There has to be very good adhesion between the foam and the skin layer in order to attain an op¬ timal rigid structure. Consequently, the foam and skin have to be coextruded in such a way that an integrated multilayer structure is produced.

Suitable materials for producing the extruded parison having a monolayer or multilayer structure comprise in prin¬ ciple all extrudable thermoplastics having sufficient rigi¬ dity. Especially suited thermoplastics are polyolefins such as polyethylene (PE) and polypropylene (PP) , polyvinyl chloride (PVC), acrylonitrile butadiene (ABS), styrene plastics, poly- amides (PA) and polycarbonates (PC). Among these, polyolefin materials are preferred. However, there is nothing to prevent the foam material and the skin layer(s) from being made of different materials. For instance, an inside layer of high density polyetylene (HDPE) and an outside layer of ultrahigh molecular weight high density polyethylene (HMW-HDPE) and an intermediate layer of a foamed polyethylene will comprise a suited structure. Another structure has an inside layer of PP homopolymer, an outside layer of PP block copolymer, and an intermediate layer of foamed PP. Of course, other structures are also possible and fall within the scope of the invention.

The materials constituting the solid part of the ex¬ truded multilayer structure can, if desired, be reinforced with cut glass fibers and/or long glass fibers in the direc- tion of extrusion.

During extrusion of the parison and forming of the components of the pallet, manufacturing waste will be produced which, for economic reasons, should be returned to production. This can be done by incorporating the waste material into one or more layers in the coextruded multilayer structure. Conse¬ quently, in a practical embodiment of the invention, it will be advantageous to use materials that can be mixed with one another. Polyolefin materials are excellently suited in this respect, especially certain types of polypropylene (PP) and high-density polyethylene (HDPE). Smaller amounts of glass fibers in the skin layers can after grinding of the material be re-extruded and without problems included in the skin layers, and even in the foam layer(s).

It is also possible to add to the thermoplastics crosslinking agents in order to crosslink the material in the pallets produced. The disadvantage is that this kind of manu¬ facturing waste cannot be recycled. Another disadvantage is that the pallets then as a rule can be joined together only mechanically, though there do exist silane-based crosslinking agents that can be crosslinked after the finished pallet has been made.

Because articles made from plastic materials have a slippery surface, and especially articles made from polyole¬ fins like HDPE and PP, it will often be desirable to add to the pallet deck a friction-increasing material. This can be done by extruding on the outside of the parison an extra layer with a friction material in a width from narrow strips to a continuous facing around the entire periphery of the parison 5 or around parts of its periphery. The friction material on the top of the pallet deck will prevent goods from sliding off the pallet, while the friction strips on the bottom will prevent the pallet from sliding easily off truck forks when the pallet is being handled. Alternatively, the friction material coating o may be applied onto the pallet deck of already fabricated pal¬ lets. This can easily be performed by extrusion coating, for instance by conveying the pallets underneath a stationary ex¬ truder in a coating line.

Preferably, the friction material is applied to the pallet in the form of parallel, raised longitudinal sections having a height of about 1 mm and in a width from narrow strips to a continuous facing. When the pallet is fabricated from a polyolefin material, a suitable friction material is selected among polyolefin-containing materials such as EVA, 0 EBA and the like.

It is of course possible to add to the plastic mater¬ ials the additives and auxiliary agents that are customary for thermoplastics, such as antistatic agents, heat and UV stabil¬ izers, colorants, etc. The various layers of the multilayer 5 structure can be of dissimilar colors, as desired. It is also possible that pallets intended for dissimilar purposes can have different colors.

The pallet deck and the sheet pallet legs along the sides of the pallet are formed in one forming step into one o predominantly flat article. The side parts of this article are then brought into a position perpendicular to the main sheet and fastened, e.g. by welding, in this position. The fastened side sheets will thus constitute one set of integrated pallet sheet legs made from the same sheet structure as the rest of 5 the article, i.e. the pallet deck.

In one embodiment of the pallet, it has sheet legs only along two opposite sides. To stabilize the legs it may be convenient to provide runners fastened to the bottoms of two corresponding opposite sheet legs. This is particularly appro- priate when the sheet legs have openings cut through their edges, e.g. three separate sheet legs along each longitudinal side of the pallet and runners fastened to the bottoms of each pair of opposite sheet legs in the transverse direction of the pallet.

In its simplest embodiment the pallet has sheet-like legs both along its longitudinal and transverse sides, and no legs in the center on the bottom. The sheet-like legs are joined together in the corners where they meet to obtain a rigid construction. The fields of use of such a pallet will normally not require any additional pallet legs.

Any combination of sheet-like legs in the longitudin¬ al and/or transverse directions of the pallet is contemplated by the present invention. When the pallet shall carry greater loads, additional legs intended for carrying the substantial part of the load must be provided, usually fastened to the bottom of the pallet deck at equal distances from and parallel to the sheet legs. Such legs may be of various constructional designs.

Detailed description of drawings

Preferred embodiments of the pallet will now be explained in more detail with reference to the attached draw¬ ings. Fig. 1 shows one particular embodiment of the finish¬ ed pallet, 1, with the pallet deck, 2, sheet legs, 3, and leg members comprising more block-shaped pallet legs, of which only one is seen in the figure.

Fig. 2 demonstrates the principle of forming the sheet legs. During the forming of the parison V-shaped grooves, 5, are impressed into the sheet in its whole length in the direction of extrusion and/or in its transverse direc¬ tion at specific distances from the side edges of the sheet. These grooves are given a bottom angle of approximately 90 ° , and a suitable depth; however, the wall thickness in the bot¬ tom of the grooves must be sufficient to avoid that the mater¬ ial break during the subsequent manufacturing steps. After that the formed sheet has been removed from the mold, the side parts, 3, of the sheet are bended along the V-shaped grooves until a position perpendicular to the main sheet and then fas¬ tened in this position. This operation is indicated by the dotted lines in figure 2. Thus, the main sheet, 2, will con¬ stitute the pallet deck and the side parts, 3, will constitute the sheet legs. The thickness of the main sheet, 2, is prefer¬ ably greater than the thickness of the side sheet parts, 3. This difference in thicknesses is achieved by regulating the circumferential thicknesses of the parison, as explained above, and make the final dimension adjustments in the forming tool. This thickness difference will contribute to obtain a rounded off transitional part between the pallet deck and the sheet legs.

The pallet normally requires openings in the sheet legs to allow truck forks to be easily inserted so the pallet can be easily lifted and transported. Figure 3 shows one em¬ bodiment of the sheet legs, 3, provided with approximately rectangular openings having rounded off corners. Obviously, the openings can be of any suitable shape. Another embodiment of the sheet legs is shown in figure 4, where said openings are expanded out through the bottom edge of the side sheet, resulting in three separate sheet legs, optionally two inter¬ spaced sheet legs. The desired openings in the side sheets are marked during the forming in the mold by impressing the con¬ tours of the openings and after the pallet has been formed the indicated parts are forced out.

In the embodiment of the pallet shown in figure 1, posts which will constitute one set of pallet legs are deep- drawn in the bottom of the pallet deck in its center long¬ itudinally and parallel to the sheet legs. In fig. 1 only one post at one end of the pallet can be seen. Normally, there are three deep-drawn posts evenly distributed along the center line of the pallet, one post at each end of the pallet and one in the middle. This is indicated in figure 5, which is a sec¬ tional view which runs through the pallet at section A-A in figure 1. The posts, 4, can be deep-drawn in one operation to their final depths, thus constituting one set of final block- shaped pallet legs. The disadvantage of deep-drawing said pal¬ let legs to full depths is that the wall thicknesses in the bottom corners of the posts will become small. The properties of the material from which the pallet is manufactured deter¬ mine the allowed deep-draw ratios, wall inclinations, shape of corners, etc. The problems related to deep-drawing thermoplas¬ tics are common knowledge to persons skilled in the art. An optional embodiment of the block-formed pallet legs is shown in figure 6. Each post, 4, is deep-drawn to a depth less than the final depth, for example to half the height of the final pallet leg. To the bottom of said half- sized post, 4, a separately produced block, 6, is then fastened in a particular operation. In principle, such blocks may be of any shape and produced from any material, provided that they can be permanently fastened to the bottoms of the half-sized posts. The blocks, 6, must have such a height that they, when combined with the deep-drawn posts, 4, produce pallet legs of correct heights. The advantages of this em¬ bodiment is that the necessary deep-draw ratios of the posts become smaller, and the pallet legs will become stronger.

Instead of using such blocks, all of them can be re¬ placed by one runner component, such as the one, 9, shown in fig. 7. This runner component consists of a cross member, 10, having two or more upward-facing posts, 11, which are fastened by their tops to the bottoms of the posts, 4, deep-drawn in the deck, 2.

In another embodiment similar runner components may be fastened to the bottom surfaces of sheet legs along oppo¬ site sides of the pallet. The height of a possible deep-drawn leg structure in the center of the pallet must then be adapted to the particular design of the runner. Such a runner may be similar to the runner, 9, shown in figure 7. In a preferred embodiment half-sized posts, 4, as shown in figure 6, are deep-drawn in the bottom of the deck, and the runners are fur¬ nished with a center post that matches post 4 of the pallet, while the posts at the ends of the runners must have a height adapted to the sheet legs, 3. Thus, the bottom part of the cross member of the runner component, 10, will face the floor.

Figure 7 shows an embodiment of the pallet where a continuous U-shaped profile, 7, is thermoformed in the bottom side of the deck in the whole length thereof in its center longitudinally and parallel to the sheet legs, 3. The upper spacer component, 8, is fastened by its cross member, 10, to the bottom of the U-shaped profile, 7. The lower runner com¬ ponent, 9, is fastened by the tops of its posts, 11, to the bottom of the matching posts, 11, on the upper spacer compon- ent, 8. Each spacer and runner is manufactured in a particular operation by forming a parison into a cross member, 10, with posts, 11.

Fig. 8 is a sectional view through the finished pal¬ let, 1, at section B-B in Fig. 7. The section runs through the pallet deck, 2, the U-shaped profile, 7, and posts, 11, on the upper spacer component, 8, and lower runner component, 9. The U-profile, 7, is formed into a channel, 12, and two closed hollow spaces, 14. The upper spacer component, 8, is shaped so that a channel formed on the top of the cross member and long- itudinally has the same width as the channel, 12, in the bot¬ tom of the U-profile. Consequently, a closed channel, 12, ex¬ tending longitudinally along the pallet is created when the pallet deck, 2, and the upper spacer component, 3, are joined together. The channel's length, width and depth can be made to fit the requirements. The U-profile, 7, and the upper spacer component, 8, are formed so that each channel, 12, is sealed at each end so that a closed hollow space is created. Option¬ ally, the forming can be such that the channel is open at both ends. The lower runner component, 9, is in principle formed like the upper spacer component, 8, but so that the cross mem¬ ber, 10, constitutes the surface facing the floor. Each post on the upper spacer component, 8, and lower runner component, 9, is formed as a symmetric profile so that two like-shaped hollow spaces, 15, and a channel, 13, are created, that will also create a closed hollow space. The shape of the pallet's posts can differ designwise from that sketched in Fig. 8 by variations in the dimensions of the channel, 12, and hollow spaces, 13 and 15. However, the bearing walls in the posts must be formed so that a sufficiently rigid structure is at- tained.

A suitable stiffening section can be inserted into the channel, 12, in Fig. 8, to ensure that the pallet does not deflect at its center under great stress. Preferably, sections made of a lightweight metal, plywood, reinforced thermoset plastics (e.g. GRP) , or other suitable plastic materials or composites are used in order to keep down the pallet' s un¬ loaded weight.

As mentioned above, pallets having sheet legs along two opposite sides may have runners fastened to the bottoms of corresponding pairs of opposite legs. Such runners are made by laying flat the extruded parison and shaping it into a flat, double sheet. During this forming there are impressed V-shaped grooves at a certain distance from each end, as explained above. Finally, the end parts are bent along said V-shaped grooves into a desired angle (e.g. 90 °) to the main cross member and fastened in such a position. Each runner is then fastened by the top surfaces of its ends to the bottoms of the appropriate sheet legs of the pallet. However, this embodiment involves a number of welding operations for each pallet: the integrated sheet legs of the pallet are fastened in their correct positions by welding, as explained above; the end parts of each runner are welded in their correct posi¬ tions, usually in a perpendicular position, to the cross mem- ber; and finally the runner are fastened by its end top sur¬ faces to the bottom surfaces of said sheet legs. To simplify the assembly of such a pallet the sheet legs of the pallet may be deleted and each runner fastened by the top surfaces of its ends directly to the bottom of the pallet deck. The individual components of the pallet can be join¬ ted together most expediently by welding, preferably by butt welding, but other methods of joining like extrusion welding, the use of glue or adhesive, and mechanically joining, can also be employed. The pallet deck can have a flat surface or a profiled surface. A particularly preferred embodiment of a pallet hav¬ ing a profiled deck is shown in figures 9 and 5.

Fig. 9 is a top view of a pallet, 1, having channels, 16, impressed into the pallet deck, thus creating raised sec- tions, 17, running in the transverse direction of the pallet.

Fig. 10 is a side view showing the longitudinal side of the pallet in Fig. 9.

The dimensions of such raised sections and impressed channels, i.e. their lengths, widths and heights, can be chos- en freely within the physical limits set by the extruded pari¬ son and the forming conditions. The bottom of the pallet deck may be given a similar design as the top surface of the deck, or it may be kept even. In principle, the raised sections in s the top and bottom surfaces of the pallet deck may run in any direction, also in different directions. In the particular embodiment of the pallet shown in Figs. 9 and 10 the width of each raised section is about 35-40 mm, and the distance bet¬ ween any two adjacent raised sections, i.e. the width of the o impressed channels, is of approximately the same magnitude. The height of each raised section is about 10 mm.

It should be obvious that in principle the top sur¬ face, optionally also the bottom surface, of the pallet deck can be given any shape or design of patterns: the only re¬ s striction being the technical conditions mentioned above. All such designs are comtemplated by the present invention.

Pallet decks having raised sections may provide a simplified unloading of the goods that they carry. For in¬ stance, the pallet indicated in Figs. 9 and 10 allows speci- o fically designed forks to be inserted into the channels in the upper pallet deck underneath the goods, which may then be re¬ moved as one unit from the pallet by the use of an adequate lifting device. This is particularly useful when unloading unit loads, such as goods shrink-wrapped in plastic films, 5 bottle crates, etc.

In the foregoing preferred embodiments of the pallet have been explained in reference of pallets having a rectan¬ gular shape. Obviously, the pallets may be of a square shape or any other suitable geometrical shape. Further, references o to longitudinal sides and transverse sides of the pallet can be interchanged without deviating from the scope of the inven¬ tion.

The above description is provided for a clearer understanding of the principles of the invention. Variations 5 in designs and embodiments of the present pallets based on the technical concepts explained above are considered being within the scope of the present invention.

Claims

1. A pallet made of a thermoplastic material, the pallet com- prising a deck and legs disposed underneath said deck, characterized by said pallet deck having top (2 ) and bottom surfaces and a set of opposed longitudinal sides and a set of opposed transverse sides, and sheet legs (3) integrated with said deck and disposed along at least one of said set of sides o of said pallet deck, said pallet having been fabricated by thermoforming an extruded thermoplastic parison having a mono¬ layer or multilayer structure into one predominantly flat article having a set of opposed longitudinal sides and a set of opposed transverse sides, and bending at least one of said s set of sides of said article into a position perpendicular to the main part of said article to form the sheet legs and affixing said sheet legs into said position.

2. A pallet according to claim 1, characterised by 0 further comprising at least two pallet deck posts formed in the bottom surface of said pallet deck, said pallet deck posts being situated at a longitudinal center of said pallet deck to function as load-carrying pallet legs.

5 3. A pallet according to claim 2, characterized in that said pallet deck posts (4) are block-shaped and of a height less than the final height of the plastic pallet, and fastened to a bottom surface of said block-shaped posts (4) separately produced leg structures, said leg structures being of a height o such that when fastened to said pallet deck posts (4) pallet legs of a desired height are obtained.

4. A pallet according to claim 3, characterized in that said separately produced leg structures comprise blocks (6) 5 which are fastened to said bottom surface of said block-shaped posts (4) .

5. A pallet according to claim 3, characterized in that said separately produced leg structures comprise a separately thermofor ed runner component ( 9 ) shaped as a cross-member (10) having at least two upward-facing runner posts (11), and that said runner component is fastened by a top surface of said runner posts to said bottom surfaces of said pallet deck s (4).

6. A pallet according to claim 1, characterised by com¬ prising one set of sheet legs (3), and further comprising a thermoformed U-shaped profile (7) in the bottom surface of o said pallet deck in the whole length thereof in its center longitudinally and parallel to said sheet legs, and fastened to the bottom of said U-shaped profile, one separately manu¬ factured pallet leg structure comprising an upper spacer com¬ ponent ( 8 ) and a lower runner component ( 9 ) ; said upper spacer s component (8) comprising a cross member (10) having downward- facing posts (11); and said lower runner component (9) com¬ prising a cross member (10) having upward-facing posts (11); said upper spacer component being fastened by its cross member to a bottom surface of said U-shaped profile (7); and said 0 lower runner component being fastened by top surfaces of its upward-facing posts to bottom surfaces of the matching down¬ ward-facing posts (11) on said upper spacer component.

7. A pallet according to claim 6, characterized in that 5 at least one of said upper spacer component ( 8 ) and said

U-shaped profile (7) facing said upper spacer component are formed with a longitudinal recess so that a straight open channel (12) is created between said upper spacer component (8) and said deck, into which a stiffening section may option- 0 ally be inserted.

8. A pallet according to any of claims 1 to 7, charac¬ terized in that the sheet legs (3) include openings to allow truck forks to be inserted. 5

9. A pallet according to claim 8, characterized in that said openings are expanded out through the bottom edge of said side sheets to create at least two interspaced sheet legs (3 ) .

10. The pallet of claim 9, characterized in that one run¬ ner component is fastened to a bottom of each pair of said sheet legs along opposite sides of said pallet deck, each said runner component ( 9 ) being produced separately and comprising posts (11) of heights adapted to the sheet legs (3).

11. A pallet made of a thermoplastic material, the pallet comprising a deck and at least two runners disposed underneath said deck, characterized by said pallet deck having top and bottom surfaces, said runners being in the shape of a cross member having a upward-facing runner post in each end thereof; said runners being fastened by a top surface of said runner posts to said bottom of said pallet deck; said pallet deck having been produced by thermoforming an extruded plastic par- ison having a monolayer or multilayer structure into one pre¬ dominantly flat article, said runners having been produced separately by thermoforming an extruded parison identical to the one used in the production of said pallet deck into a pre¬ dominantly flat article and bending the end parts of said lat- ter article into a position perpendicular to the main part of said latter article to obtain said runners having upward-fac¬ ing posts.

12. A pallet according to any of claims 1 to 11, charac- terized in that said parison is extruded from a thermoplastic selected from polyolefins, PVC, ABS, styrene plastics (PS), polyamides (PA) and polycarbonates (PC) .

13. A pallet according to any of claims 1 to 12, charac- terized in that said extruded structure is a coextruded inte¬ grated multilayer structure comprising at least one foamed plastic layer having a solid skin on both sides thereof.

14. A pallet according to any of claims 1 to 13, charac- terized in that said extruded structure comprises at least one polyolefin material.

15. A pallet according to claims 12, 13 or 14, character¬ ized in that said thermoplastic is reinforced with a reinfor- cing material selected from cut glass fibres and long glass fibres.

16. A pallet according to any of claims 1 to 15, charac- s terised in that at least said top surface of said deck is fur¬ nished with a plurality of parallel, raised longitudinal sec¬ tions made of a friction material.

17. A pallet according to claim 16, characterised in that

10 the parallel, raised longitudinal sections have a height of about 1 mm and a width of from narrow strips to a continuous facing.

18. A pallet according to any of claims 1 to 15, charac- i5 terised by comprising a friction material extruded onto said top surface of said plastic pallet deck.

19. A pallet according to one or more of the above claims, characterized by said top surface, and optionally also

20 said bottom surface, of said pallet deck being profiled with impressed channels (16) and raised sections (17) of desired dimensions.

25

5