Pallet and method of manufacturing the same

Abstract

An expanded polystyrene pallet is formed by molding and expanding polystyrene beads to form a pallet body comprising a shelf (2) for bearing the load and a plurality of supporting feet (3) integral with the shelf and a layer (4) of vitrified glass-like polystyrene at the lower surface of said supporting feet.

Description

[0001] PALLET AND METHOD OF MANUFACTURING THE SAME

[0002] FIELD OF THE INVENTION

[0003] The present invention concerns pallets used for storing and transporting goods and a method of manufacturing them.

[0004] KNOWN PRIOR ART

[0005] Pallets have been used for a long time for moving and transporting goods so as to facilitate the lifting and handling of goods born on the pallet by means of forklifts and, in some cases, so as to allow them to be stacked in warehouse.

[0006] Traditionally, most handling and transporting pallets are made of wood; although such wooden pallets have generally proven satisfactory and have been widely accepted, they have a number of drawbacks. In fact, even the lightest wooden pallets are anyhow relatively heavy as they weigh an average of 15-17 kg, tend to absorb moisture and must be treated with chemical products to prevent them from being colonized by insects with consequent degradation of the structure.

[0007] Generally, wooden pallets are not considered suitable for transporting food products due to possible infestations of insects, molds and bacteria. Wooden pallets are further inappropriate for use in some environments due to splinters that can be generated following impacts when used with forklifts.

[0008] Moreover, obsolete pallets are not easily recyclable and many must be disposed of in landfills, resulting in cost increases for the user. The drawbacks set forth above, combined with an increasing cost of timber, make it necessary to identify pallets other than wooden pallets.

[0009] Traditionally, alternative pallets to wooden ones have been made of a rigid plastic material. However, plastic pallets do not provide a satisfying solution to the problems discussed above. Plastic pallets, generally made by injection or rotational molding, are as heavy as or even heavier than wooden pallets. They tend to have slippery surfaces and are subjected to damage during use, such as for example chipping from impact with the forklift; generally, plastic pallets are not considered suitable for use in the transport of food products due to the possibility of chipping. Expanded polystyrene (EPS) pallets are known in the art. Such pallets are much lighter than wooden or plastic ones but have not fully solved the previous problems since they generally provide unsatisfactory performance for reasons of resistance and handling. In the past, various solutions to improve the performance of EPS pallets have been suggested providing, for example, to make only part of the pallet in EPS equipping the pallet with rigid bottom supports. US2017 / 239860 describes a pallet provided with inner or outer reinforcements made of plastic material different from expanded polystyrene.

[0010] The use of chemically modified polystyrene was also suggested to improve the final expanded product’s resistance against impacts.

[0011] The solutions set forth above have the great drawback of preventing or hindering recycling of the pallet at the end of its lifespan.

[0012] Therefore, there is the need to provide an EPS pallet and a method of manufacturing it which allows to solve the problems of the known art in a simple and economical way.

[0013] Object of the present invention is to provide an EPS pallet which is entirely made of polystyrene, without profiles or inserts made of an engineered plastic material and having improved characteristics of impact, wear and load resistance with respect to known pallets. A further object of the invention is to provide a method of manufacturing the pallet discussed above. A further object of the invention is to provide a pallet devoid of foreign plastic materials, i.e. a fully recyclable pallet which does not require treatments for removing parts of the pallet.

[0014] SUMMARY OF THE INVENTION

[0015] Such objects are achieved by the present invention, which concerns a pallet according to claim 1 and a method of manufacturing it according to claim 7.

[0016] The invention concerns an expanded polystyrene pallet comprising an expanded polystyrene body, said body comprising a deck for bearing the load and a plurality of supporting feet integral with said load bearing deck, characterized in that at least the lower supporting surface of said feet is provided with one layer of vitrified glass-like polystyrene. The term layer of vitrified glass-like polystyrene means the polystyrene obtainable by carrying out the expansion of the cells under high pressure in a process known in the art, for example for manufacturing ice cream tubs with vitrified inner surface. In an embodiment, the vitrified layer is formed by using steam at 9 bars during the expanding and molding step. This way, the foam cells of the outer layer are reduced to a vitrified layer during the molding of the piece.

[0017] According to an aspect of the invention, the thickness of the layer of vitrified glasslike polystyrene, i.e. of the expanded and compacted vitrified glass-like layer, is sufficient for imparting rigidity to the pallet surface intended to provide contact with the ground, although keeping the value of said thickness as small as possible. In an embodiment, said thickness is at least 0.2mm, preferably within the range from 0.2 to 0.8 mm, more preferably from 0.2 to 0.5 mm.

[0018] The presence of the vitrified glass-like layer on the surface of the base of the supporting feet has the advantage of providing a rigid surface with a low friction coefficient so as to facilitate the handling of the loaded pallet. In other words, the risk of feet breaking at least partially while using the pallet is drastically reduced when it is dragged along the ground or floor of a plant,. Moreover, the foot substantially remains intact, also in the event of breakage and crack formation in the vitrified glass-like layer.

[0019] The thickness is advantageously within the range from 6 cm to 10 cm, preferably from 7 cm to 9 cm. The height H of the feet is selected depending on the use of the pallet; for example, the height of the foot for a pallet truck is 9 cm.

[0020] According to an aspect of the invention, before being expanded, the polystyrene beads are sized within the range from 0.6 to 3.0 mm, preferably from 0.7 to 2.0 mm. In other words, before expansion the sizes of the polystyrene beads fall within such range, preferably within the preferential range 0.7 - 2.0 mm. In the expanded polystyrene body, the polystyrene cells have preferential sizes from 2.5 to 5.0 mm; preferably, the expanded polystyrene particles have an average size of 4.0 mm in the deck and decrease with the increase in density when moving from the deck to the feet portion and up to the vitrified glass-like portion present at the base of the feet.

[0021] The expanded polystyrene body has different density in different portions of the body itself; in particular, the density of the deck is less than the density in the foot portions. Preferably, the expanded polystyrene body has density in the range from 23 to 45 kg / m3, excluding the vitrified glass-like layer. Typically, the density of the deck is from 25 to 35 kg / m3and the density of the foot portion, at about 5 cm from the base, is 40-45 kg / m3; the density of the vitrified glass-like layer can reach about 600 kg / m3. The selection of the density of the deck (also in combination with the sizes of the foam cells) has the advantage of providing a deck sufficiently flexible to reduce the possibility of breaking it.

[0022] According to an aspect of the invention, there are three to nine supporting feet; in the embodiment in which there are three supporting feet, the same extend transversely below said deck, i.e. they extend from one side to the opposite side of the pallet.

[0023] The invention further concerns a method of manufacturing an expanded polystyrene pallet, comprising the steps of expanding polystyrene beads to form a pallet body comprising a deck for bearing the load and a plurality of supporting feet integral with said deck, characterized by treating at least the lower surface of said supporting feet to provide a layer of non-expanded polystyrene to said lower surface.

[0024] According to an aspect, the treatment is carried out to reach a thickness of said nonexpanded polystyrene layer of at least 0.2 mm, preferably the thickness is in the range from 0.2 mm to 0.8 mm, more preferably from 0.2 to 0.5 mm. In an embodiment, the expanded polystyrene layer, i.e. the layer being expanded at the base of the feet, is brought to a non-expanded layer condition during the step of molding the pallet, i.e. by means of the so-named vitrification of expanded polystyrene.

[0025] Said vitrification is typically achieved by supplying high pressure steam in the mold zone corresponding to the base of the feet. In an embodiment, the steam pressure is in the range from 7.5 to 10.0 bars, preferably about 8.5 bars or 9 bars.

[0026] The invention further concerns a pallet and load system comprising a pallet as described above and a load, said pallet bearing said load arranged thereon, characterized by comprising a tubular plastic element which envelops said load and at least part of the side of said deck, wherein said tubular element is closed on its portion above said load and substantially sealingly closes on the vertical side of the deck of the pallet. According to an aspect, the plastic tubular element is of the stretchable type, i.e. it can be elastically extended in the step of applying it over the pallet and the load, so that it clings to the vertical wall of the pallet when released.

[0027] BRIEF DESCRIPTION OF THE FIGURES

[0028] The invention will now be described in more detail with reference to the drawings attached by way of example and without limitations, in which:

[0029] Fig. 1 is a schematic sectional side view of a pallet according to an embodiment of the invention;

[0030] Fig. 2 is schematic bottom view of the embodiment of fig. 1;

[0031] Fig. 3 is a schematic bottom view of a further embodiment of a pallet; Fig. 4 is an enlarged view of a part of the pallet body of fig. 1;

[0032] Fig. 5 is a side view of a pallet, load and cover system according to the invention.

[0033] DESCRIPTION OF SOME EMBODIMENTS

[0034] Initially with reference to fig. 1, the pallet P according to the invention has an expanded polystyrene body 1 comprising a deck 2 which has the function of bearing the load and a plurality of supporting feet 3 extending below the deck and integrally made, i.e. in one piece, with said deck for bearing the load.

[0035] The thickness of the deck 2, corresponding to the side 7 thereof, is within the range from 6 cm to 10 cm, preferably from 7 cm to 9 cm. The deck extends continuously, i.e. does not have holes or other interruptions and forms a continuous layer for bearing the load. Advantageously, this characteristic allows to isolate the load from the environment below the pallet.

[0036] According to the invention, at least the lower supporting surface of said feet 3 is provided with a layer 4 of vitrified glass-like polystyrene, i.e. in a non-expanded condition. The thickness of the polystyrene layer 4 is preferably at least 0.2mm, preferably within the range from 0.2 to 1.5mm, more preferably within the range from 0.2 and 0.5 mm. The layer 4 is integral with the pallet body and is preferably made during the pallet molding step, with a so-named vitrification process.

[0037] The presence of a vitrified glass-like layer 4, i.e. no longer expanded, has the advantages of reducing the friction of the lower surface of the supporting feet and making it more resistant. Moreover, the method used allows to avoid to separately manufacture supporting portions which must be assembled with pallet body.

[0038] As known, expanded polystyrene is formed by a plurality of expanded cells integral with one another. In the pallet body, except for the layer 4, the cells 9 are expanded in shape and have, as depicted in fig. 4, a size D within the range from 2.5 to 5.0 mm; preferably, the expanded polystyrene particles have an average size of 4.0 mm in the deck. The density increases when passing from the deck to the foot portion and up to the vitrified glass-portion present at the base of the feet.

[0039] The beads, i.e. the polystyrene particles used in the expanding step have sizes of at least 0.6 mm, preferably within the range from 0.6 to 3.0 mm, and more preferably within the range from 0.7 to 2.0 mm.

[0040] The pallet according to the invention has an expanded polystyrene body 1 with density in the range from 28 to 35 kg / m3. In particular, the combination between the sizes of the cells and the density of the body 1 results in structure flexibility and thus greater resistance of the same against breaking.

[0041] The number of supporting feet 3 of the pallet is typically three or nine depending on the desired model. As visible in fig. 2, in the embodiment with three supporting feet, the same extend transversely below the deck 2 and extend from one side to the other of said self.

[0042] The pallet can be of different shapes or sizes depending on its intended use. For example, the deck of the pallet can be of rectangular shape with dimensions of 120cm x 100 cm; in the event of pallets intended for transporting large bags of granules of polymeric material, the pallet can have a hexagonal or octagonal shape, with consequent savings on materials used for the pallets.

[0043] The method of manufacturing expanded polystyrene pallets according to the invention comprises the steps of expanding polystyrene beads, known per se in the art, to form a pallet body 1 comprising a deck 2 for bearing the load and a plurality of supporting feet 3 integral to said deck 2. The method further involves treating at least the lower surface of said supporting feet 3 to provide a vitrified glass-like layer 4 to said lower surface, i.e. in a compact and non-expanded condition. With reference to figure 5, a pallet and load system comprising a pallet according to the invention and a load 6 placed on said pallet, is schematically shown. The pallet has a vertical side 7, i.e. a thickness, forming a continuous perimeter surface. According to the system of the present invention, the load 6 is protected by a tubular element 8 made of plastic material which envelops said load and at least part of the side 7 of the deck 2.

[0044] The tubular element 8 is closed above and open below; as shown with a dashed line in fig. 5, the element 8 is initially in the shape of a tubular element open on both sides and can be formed, for example, from a continuous tubular element made of a stretchable film, i.e. elastically extendable, which is extended and lowered over the load up to the level of the deck 2 of the pallet. When the tubular element is released, the stretchy or rather elastic nature of the film (together with the diameter of the tubular element) causes the lower end of the covering tubular element 8 to cling to the side 7 of the deck 2 of the pallet P. The tubular element is thus closed, for example by cutting and welding, in a position above that of the load 6; this results in a sealing covering of the load 6.

[0045] The pallet according to the present invention thus has numerous advantages. It is entirely made of polystyrene, most in the form of expanded polystyrene, without requiring the presence of additional stiffening or supporting elements. This way, the pallet can be fully recycled at the end of its lifespan. It is resistant to the loads and stresses to which it can be typically subjected in its conditions of use. It is light and thus allows considerable savings in transportation costs. It is economical to manufacture and recycle.

[0046] Moreover, the pallet and load system according to the invention is able to insulate the load from outer agents, even when kept outside. This characteristic is extremely useful whenever the loads consist of or comprise flammable products, such as, for example, pre-expanded polyurethane beads containing pentane. Thanks to the system of the invention, the loaded pallets can be kept outside rather than in a covered structure, thus avoiding to have to provide safety and fire prevention devices in the covered structure, with obvious economic advantages. The presence of a vitrified single-body glass-like layer, i.e. made integral to the pallet body while molding, allows to reduce the manufacturing costs with respect to known pallets provided with additional structures and elements. Since the vitrified glass-like layer is made of polystyrene, the pallet is made of a single material and is easily recycled. Moreover, the reduced thickness of the vitrified glass-like layer, as described above, results in the advantage that the vitrified glass-like layer particles present in a plate of expanded polyurethane made from the recycled pallet, are quantitatively present in a very low percentage, so that no problems occur in the manufacturing steps of said plates, in particular in the cutting step.

Claims

CLAIMS1. An expanded polystyrene pallet comprising an expanded polystyrene body (1) including a plurality of polystyrene cells (5), said body comprising a deck (2) for bearing a load and a plurality of supporting feet (3) integral with said load bearing deck (2), characterized in that at least the lower supporting surface of said feet (3) is provided with one layer (4) of vitrified glass-like polystyrene.

2. Pallet according to claim 1, wherein the thickness of said layer of vitrified glass-like polystyrene is at least 0.2 mm, preferably within the range from 0.2 to 0.8 mm, more preferably from 0.2 to 0.5 mm.

3. Pallet according to claim 1 or 2, wherein the dimensions of said polystyrene cells are in the range from 2.5 to 5.0 mm, preferably from 3.0 to 4.5 mm and more preferably in the range from 3.8 to 4.2 mm at least in said deck (2).

4. Pallet according to one of the preceding claims, wherein said expanded polystyrene body (1) has a density in the range from 28 to 35 kg / m3and wherein the density at the feet part (3) of said body (1) is greater than the density at said deck (2).

5. Pallet according to one of the preceding claims, wherein between three to nine supporting feet (3) are provided and wherein three supporting feet extend transversely below said deck.

6. Pallet according to one of the preceding claims, wherein the thickness of said deck (2) is in the range from 6 cm to 10 cm, preferably from 7 cm to 9 cm.

7. A method of manufacturing an expanded polystyrene pallet according to one of claims 1 to 6, comprising the steps of molding and expanding polystyrene beads to form a pallet body (1) comprising a deck (2) for bearing a load and a plurality of supporting feet (3) integral with said deck (2), characterized by making a layer (4) of vitrified, glass-like, polystyrene at least at the lower surface of said supporting feet (3) during said molding step.

8. Method according to claim 7, wherein the thickness of said layer of nonexpanded polystyrene is at least 0.2 mm, preferably in the range from 0.2 to 0.8 mm, more preferably from 0.2 to 0.5 mm.

9. Method according to claim 7 or 8, wherein polystyrene beads to be expanded and which are sized within the range from 0.6 to 3.0 mm, preferably from 0.7 to 2,0 mm, are used.

10. A pallet and load system comprising a pallet according to one of claims 1 to 6 and a load (6) placed on said pallet, characterized by comprising a tubular covering element made of plastic material which envelops said load and rests on the side (7) of said deck (2), said tubular element (8) being closed on its portion above said load.

11. A pallet and load system according to claim 10, wherein said tubular covering element is made of a material elastically extendable transversally to its axis.

Images