Plastic transportation pallet

Abstract

The invention is in the field of plastic transportation pallets. In particular, the invention is directed to a transportation pallet, a polymeric composite and a method of forming a transportation pallet. The transportation pallet of the invention comprises a polymeric composite, comprising - 60 wt.% to 90 wt.% based on the total weight of the polymeric composite of low-density polyethylene based resin, wherein the low-density polyethylene based resin comprises low-density polyethylene in an amount of 50 wt.% or more by total weight of the low-density polyethylene based resin, and wherein the low-density polyethylene based resin has a melt mass-flow rate in the range of from 0.1 g / 10 min to 50 g / 10 min, as determined according to ISO 1133-1 at 190 °C with a load of 2.16 kg; - 10 wt.% to 30 wt.% based on the total weight of the polymeric composite of modulus enhancer additive; and - 0 wt.% to 10 wt.% based on the total weight of the polymeric composite of polymer processing additive.

Description

[0001] P138500PC00

[0002] Title: PLASTIC TRANSPORTATION PALLET

[0003] The invention is in the field of plastic transportation pallets. In particular, the invention is directed to a transportation pallet, a polymeric composite and a method of forming a transportation pallet.

[0004] The current logistic transportation pallet market is dominated by wooden pallets. However, according to a report from the European Pallet Association (EPAL), on average 20 % of the wooden pallets are broken during each logistic transportation cycle. This broken timber is discarded as waste and new timber needs to be harvested to replace it.

[0005] In contrast, the state-of-art plastic pallet can be used for dozens of transportation cycles without the need for repairing, thereby reducing the amount of pallet waste and the carbon-footprint associated with the use of pallets in transportation. In addition, the use of plastic pallets is preferred over the use of wooden pallets for applications with strict hygiene requirements, such as in the pharmaceutical, chemical and food sector, as plastic pallets are impervious to bacteria, fungi and pests, do not absorb moisture and are easier to clean. Furthermore, unlike wooden pallets that are discarded as waste, plastics pallets may be recyclable, thereby further reducing the amount of pallet waste and the carbon-footprint.

[0006] The state-of-art plastic pallets are usually made from polyolefins, such as polypropylene (PP), high-density polyethylene (HDPE) or a mix of polypropylene and high-density polyethylene. Those materials, as prevalent plastic materials used for rigid packaging, are showing a load capacity comparable to that of wooden pallets and a longer lifetime. The weight of these plastic pallets is about 60 % of their wooden counterparts while having comparable load carrying capacity, which further contributes to the reduction in the carbon footprint of transportation.

[0007] For example, WO-A-2013 / 122944 discloses a flame retardant pallet made from a polymeric composite material, comprising a polyolefin,preferably polypropylene, a long glass fibre reinforcement, a coupling agent and optionally a flame retardant.

[0008] WO-A-2017 / 204635 discloses a fibre-reinforced plastic object comprising 65-99.9 wt.% of a rest fraction from plastic recycling, 0.1-30 wt.% of mineral fibres, wherein the rest fraction from plastic recycling comprises 10-90 wt.% of recycled polyethylene, 10-90 wt.% of recycled polypropylene, 0.1-3 wt.% of further recycled plastics, and less than 2 wt.% of inorganic impurities.

[0009] EP-B-1 636 310 is directed to a composition comprising a synthetic polymer, a filler, and as dispersing agent an acrylic copolymer containing an alkyl acrylate or methacrylate comprising at least eight methylene groups in the side chain.

[0010] CA-A-2 369414 discloses a plastic pallet being formed of 60-90 wt.% of a thermoplastic, 10-40 wt.% of a reinforcement fibre, and a structural reinforcement in an amount to provide a final reinforcement fibre content of the pallet of between 10-40 wt.%.

[0011] Nevertheless, in comparison with the cost per use of wooden pallet, i.e. repair timber cost and repair labour cost, the cost per use of the current plastic pallet, i.e. the pallet unit price divided by the lifetime (the number of transportation cycles without breaking) is still higher than the wooden pallet, which hinders the transition towards the use of these more durable and sustainable plastic pallets.

[0012] There are two important factors that characterise the performance of a transportation pallet: the stiffness of the pallet determines the load carrying capacity, and the impact resistance of the pallet determines the lifetime. Therefore, a pallet should ideally have a high stiffness, and a high impact resistance.

[0013] The impact resistance of the pallet is determined by the impact strength of the material that the pallet is made of, while the stiffness of the pallet is determined by the tensile modulus of the pallet material.It is an object of the present invention to provide a plastic pallet with an adequate load carrying capacity and an improved lifetime.

[0014] The inventor surprisingly found that by using a specific polymeric composite, one or more of these objectives can, at least in part, be met. In particular, the pallets according to the present invention have a high tensile modulus and a high impact strength, which may lead to a significantly prolonged lifetime of the pallet as compared to conventional plastic pallets, which can potentially reduce the cost per use of this new plastic pallet to be lower than the wooden pallet to economically foster the transition towards the more sustainable plastic pallets.

[0015] Accordingly, in a first aspect, the invention is directed to a transportation pallet.

[0016] In a further aspect, the invention is directed to a polymeric composite as described herein.

[0017] In yet a further aspect, the invention is directed to a method of forming a transportation pallet according to the first aspect of the invention.

[0018] The term “tensile modulus” as described herein is used to denote the mechanical property of the stiffness of a material. It is defined as the ratio of its tensile stress to its strain when undergoing elastic deformation and can be expressed in MPa. The tensile modulus of polymers or polymeric composites can be determined using ISO standard 527.

[0019] The term “tensile strength” as described herein is in line with the definition according to ISO standard 527-1 and it represents the first local maximum observed during a tensile test. It can be expressed in MPa. The tensile strength can be determined according to ISO standard 527-1.

[0020] The term “melt mass-flow rate” as described herein is defined, in line with the definition according to ISO standard 1133-1, as the rate of extrusion of a molten resin through a die of specified length and diameter under prescribed conditions of temperature, load and piston position in the cylinder of an extrusion plastometer, the rate being determined as the massextruded over a specified time. The melt mass-flow rate describes the ease of flow of molten polymers and polymeric composites. The melt mass-flow rate can be expressed in g / 10 min and can be determined according to ISO standard 1133-1 at 190 °C and a load of 2.16 kg. The “melt mass-flow rate” as determined by ISO standard 1133-1 is equivalent to the “melt flow index” defined in ASTM D1238.

[0021] The term “Charpy notched impact strength” as described herein reflects the impact energy absorption capability of a material and is defined as the amount of energy a material is able to absorb during fracture. The Charpy notched impact strength can be expressed in kJ / m2and can be determined according to ISO standard 179-1. The terms “Charpy notched impact strength” and “impact strength” are herein used interchangeably.

[0022] The term “modulus enhancer additive” as described herein is used to denote an additive that increases the tensile modulus of a polymer composition, in particular of a low-density polyethylene (LDPE) based polymer composition.

[0023] The term “coupling agent” as described herein denotes an additive that increases the miscibility of two components in a mixture, in particular the miscibility between the low-density polyethylene based resin and the modulus enhancer additive.

[0024] The term “high-density polyethylene” (HDPE) as described herein is used to denote polyethylene with a density of between 0.94 g / cm3and 0.97 g / cm3.

[0025] The term “low-density polyethylene” (LDPE) as described herein is used to denote polyethylene with a density of between 0.87 g / cm3and 0.94 g / cm3. The classical low-density polyethylene (LDPE) has a density of from about 0.91 g / cm3to about 0.94 g / cm3, is prepared in a high-pressure free radical process and is characterised by a heterogeneous distribution of short chain branches and long chain branches. The term LDPE as used herein, however, is also meant to cover linear low density polyethylene (LLDPE),very low density polyethylene (VLDPE), and ultra-low density polyethylene (ULDPE). LLDPE is typically prepared using Ziegler-Natta catalysts, has a density of from about 0.915 g / cm3to about 0.93 g / cm3and is characterised by having a heterogeneous distribution of short chain branches, but almost no long chain branches. VLDPE and ULDPE are typically prepared using a single-site metallocene or constraint geometry catalysts and are typically characterised by having a homogeneous distribution of short chain branches. VLDPE has a density of from about 0.88 g / cm3to about 0.905 g / cm3, and ULDPE has a density of from about 0.87 g / cm3to about 0.88 g / cm3.

[0026] The invention provides a transportation pallet comprising a polymeric composite comprising a polymeric composite, comprising

[0027] - 60 wt.% to 90 wt.% based on the total weight of the polymeric composite of low-density polyethylene based resin, wherein the low-density polyethylene based resin comprises low-density polyethylene in an amount of 50 wt.% or more by total weight of the low-density polyethylene based resin, and wherein the low-density polyethylene based resin has a melt mass-flow rate in the range of from 0.1 g / 10 min to 50 g / 10 min, as determined according to ISO 1133-1 at 190 °C with a load of 2.16 kg;

[0028] - 10 wt.% to 30 wt.% based on the total weight of the polymeric composite of modulus enhancer additive; and

[0029] - 0 wt.% to 10 wt.% based on the total weight of the polymeric composite of polymer processing additive.

[0030] The low-density polyethylene based resin comprises low-density polyethylene and possibly other polyolefins and / or non -polyolefin components. Preferably, the amount of low-density polyethylene is about 60 wt.% or more by total weight of the low-density polyethylene based resin, more preferably about 70 wt.% or more, such as about 80 wt.% or more, about 90 wt.% or more, or about 95 wt.% or more.Using a low-density polyethylene based resin with a relatively high content of low-density polyethylene results in a material with extraordinary impact strength. Advantageously, the polymeric composite material may have a Charpy notched impact strength of from about 10 kJ / m2to about 50 kJ / m2for notched specimen as measured according to ISO 179-1, preferably from about 30 kJ / m2to about 45 kJ / m2. The Charpy notched impact strength of low-density polyethylene based resin may even be more than 100 kJ7m2. For comparison, the Charpy notched impact strength of conventional materials used for transportation pallets such as high-density polyethylene and polypropylene are much lower (high-density polyethylene: 5 kJ / m2to 20 kJ / m2; polypropylene: 5 kJ / m2to 15 kJ / m2). As a result of this high impact strength of the material, the pallets according to the present invention comprising the material are less likely to break during use.

[0031] The transportation pallet of the invention can favourably comprise, consist, or essentially consist of recycled low-density polyethylene based resin. This allows for better economic and sustainability performance. The recycled low-density polyethylene based resin can, for instance, comprise post-consumer recycle (PCR) low-density polyethylene and / or post-industrial recycle (PIR) low-density polyethylene. Favourably, the recycled low-density polyethylene based resin does not require a high purity in order to be suitable for use in the invention.

[0032] For example, the recycled low-density polyethylene based resin may comprise other polyolefins, such as polypropylene, medium-density polyethylene (MDPE) and / or high-density polyethylene, in an amount of up to about 65 wt.% based on the total weight of the recycled low-density polyethylene based resin, preferably from about 0.01 wt.% to about 50 wt.%, more preferably from about 0.01 wt.% to about 30 wt.%. These other polyolefins may be present because of density based sorting techniques, i.e. the water-based sink-float method which is widely used in plastic recycling,which is not capable of separating different polyolefin fractions as they are all floating in the water due to the density of the other polyolefins being about 1 g / cm3or lower.

[0033] In addition, it is sometimes preferable to use a recycled low-density polyethylene based resin with a high content of other types of polyolefins, due to the economic benefit of those other types of polyolefins. However, the low-density polyethylene based resin should have a minimum of 50 wt.% of low-density polyethylene based on total weight of the low-density based resin. This minimum amount of low-density polyethylene in the low-density polyethylene based resin enables the impact strength of the polymeric composite to be exceptionally high, such that a transportation pallet made with such material has excellent lifetime.

[0034] The recycled low-density polyethylene based resin may also comprise non-poly olefin components as impurities, such as dirt, metal, pulp, rubber, or other plastics such as polyamide and polyethylene terephthalate, which are usually laminated with low-density polyethylene together to form high performance food packaging. These non -polyolefin components may be present in an amount of up to about 10 wt.% based on total weight of the recycled low-density polyethylene based resin, preferably from about 0.01 wt.% to about 8 wt.%, more preferably from about 0.01 wt.% to about 4 wt.%.

[0035] For example, the recycled low-density polyethylene based resin may be produced according to the specification DKR 310, i.e. plastic films with a maximum of 8 wt.% of impurities, or according to the specification DKR 350, i.e. mixed plastics with a maximum of 10 wt.% of impurities, or according to any unspecific waste stream with low-density polyethylene waste as the major component. The DKR standard is established by the German “Deutsche Gesellschaft fur Kreislaufwirtschaft und Rohstoffe mbH (DKR)”. In addition, the recycled low-density polyethylene based resin maybe from other specific waste streams such as the separated waste beverage cartons in which the liner is made of or comprises low-density polyethylene.

[0036] Since the low-density polyethylene based resin in the polymeric composite can comprise recycled low-density polyethylene that may include other polyolefins with higher density (such as polypropylene,

[0037] medium-density polyethylene, and / or high-density polyethylene) and / or non-polyolefin components, the density of the overall recycled low-density polyethylene based resin in the polymeric composite can be higher than that of classical low-density polyethylene. The density of any recycled

[0038] low-density polyethylene based resin in the polymeric composite may, for instance, be from about 0.91 g / cm3to about 0.98 g / cm3, such as from about 0.92 g / m3to about 0.975 g / cm3, or from about 0.93 g / cm3to about 0.97 g / cm3.

[0039] The recycled low-density polyethylene based resin may have a tensile modulus of from about 200 MPa to about 500 MPa, as determined in accordance with ISO 527, such as from about 250 MPa to about 450 MPa, or from about 300 MPa to about 400 MPa. The recycled low-density polyethylene based resin may have a tensile strength of from about 7 MPa to about 15 MPa, as determinedin accordance with ISO 527, such as from about 9 MPa to about 13 MPa, or from about 10 MPa to about 12 MPa. The recycled low-density polyethylene based resin may have a Charpy notched impact strength of about 80 kJ / m2or more, as determined in accordance with ISO 179-1, such as about 90 kJ / m2or more, or about 100 kJ / m2or more. Suitable recycled LDPE is, for example, commercially obtainable as InfiniteFilm PE-granulate from Attero.

[0040] The low-density polyethylene based resin has a melt mass-flow rate of from about 0.1 g / 10 min to about 50 g / 10 min as measured according to ISO 1133-1 at 190 °C with a load of 2.16 kg, such as from about 0.2 g / 10 min to about 30 g / 10 min, or from about 0.5 g / 10 min to about 15 g / 10 min. The low-density polyethylene based resin may comprise, consist, or essentially consist of recycled low-density polyethylene based resin.The low-density polyethylene based resin usually has a tensile modulus of from about 200 MPa to about 500 MPa, which is about 20 % to about 50 % of high -density polyethylene and polypropylene. This means that a transportation pallet made with low-density polyethylene based resin requires at least double the amount of the material in order to obtain comparable loading capacity in comparison to the state-of-art plastic pallets made from high-density polyethylene and polypropylene. This would be neither economical nor environmental friendly.

[0041] To tackle that challenge, the polymer composite used in the transportation pallet of the invention includes a modulus enhancer additive to increase the tensile modulus of the polymeric composite to a value that is comparable to polypropylene (typically from about 1300 MPa to about 1700 MPa) and / or high-density polyethylene (typically from about 900 MPa to about 1000 MPa) used for the production of conventional plastic pallets. This comparable tensile modulus ensures that the load carrying capacity of transportation pallets comprising the polymeric composite according to the present invention is comparable to that of conventional plastic pallets. In particular, the polymeric composite may have a tensile modulus of from about 600 MPa to about 2700 MPa, as measured according to ISO 527-1, preferably from about 1000 MPa to about 1800 MPa. The polymeric composite may have a tensile strength of from about 10 MPa to about 30 MPa as measured according to ISO 527-1, preferably from about 15 MPa to about 20 MPa.

[0042] Accordingly, the polymeric composite comprises from 10 wt.% to 30 wt.% based on total weight of the polymeric composite of modulus enhancer additive, preferably from about 10 wt.% to about 25 wt.%, more preferably from about 15 wt.% to about 20 wt.%.

[0043] Those weight percentage ranges of modulus enhancer additives are preferable because if the amount of modulus enhancer additive is too high and the amount of low-density polyethylene based resin too low, thennot only will the tensile modulus of the polymeric composite be too high but also the impact resistance of the polymeric composite will be too low. This will result in a transportation pallet that is incapable of achieving the desired improved lifetime. On the other hand, if the amount of low-density polyethylene based resin is too high and the amount of modulus enhancer additive is too low, the tensile modulus of the polymeric composite will be too low. This will result in a transportation pallet that may not be sufficiently stiff to carry a sufficient amount of load. At least 10 wt.% of the modulus enhancement additives in the polymeric composite is needed to realise sufficient stiffness enhancement of the low-density polyethylene based resin and form a polymeric composite and transportation pallet with desirable tensile modulus, such as comparable to those of transportation pallets prepared from high-density polyethylene and / or polypropylene.

[0044] Accordingly, the polymeric composite preferably comprises from about 65 wt.% to about 87 wt.% based on the total weight of the polymeric composite of low-density polyethylene based resin, more preferably from about 70 wt.% to about 85 wt.%.

[0045] As the amount of low-density polyethylene in the low-density polyethylene based resin may vary, the amount of low-density polyethylene in the polymeric composite may also vary. Preferably, the polymeric composite comprises from about 30 wt.% to about 90 wt.% of low-density polyethylene, more preferably from about 65 wt.% to about 87 wt.%, even more preferably from about 70 wt.% to about 85 wt.% of low-density polyethylene, based on the total weight of polymeric composite.

[0046] Preferably, the low-density polyethylene based resin in the polymeric composite mainly comprises classical low-density polyethylene (LDPE) and / or linear low-density polyethylene (LLDPE).

[0047] Suitable modulus enhancer additives may include carbon fibre, aramid fibre, natural fibre, talc, calcium carbonate, mica, wollastonite, glassfibre, glass beads, aluminium fibre, aluminium powder, steel fibre, steel powder, or any combination thereof.

[0048] Preferably, the modulus enhancer additive is glass fibre. The high performance and low costs of glass fibre make it a preferred modulus enhancer from both a technical and economic point of view.

[0049] The effect of the glass fibre on the tensile modulus of the polymer composite, and thereby on the stiffness of the transportation pallet, depends on the length and the diameter of the glass fibre. Specifically, the tensile modulus of the composite is proportional to the length of the glass fibre and inversely proportional to the diameter of the glass fibre.

[0050] Accordingly, the glass fibre preferably has a mean average length of 0.5 cm or less, preferably about 0.48 cm or less, such as from about 0.1 mm to about 5 mm, or from about 0.2 mm to about 4.6 mm. Such mean average lengths result in good flowability of the polymeric composite during processing. In addition, if the glass fibre is too long, the tensile modulus of the polymeric composite will be too high, while the impact strength of the polymeric composite will be reduced. The average glass fibre length should preferably be at least 0.1 mm to realise stiffness enhancement of the low-density polyethylene based resin.

[0051] The glass fibre preferably has a diameter in the range of from about 5 pm to about 50 pm, more preferably in the range of from about 5 pm to about 40 pm, even more preferably in the range of from about 10 pm to about 30 pm.

[0052] Additionally, the glass fibre preferably has a Young’s modulus from about 50000 MPa to about 90000 MPa, more preferably from about 60 000 MPa to about 85000 MPa. If the tensile modulus is too high, the impact resistance of the polymeric composite may be reduced. Accordingly, the use of grade E glass fibre characterised by having a Young’s modulus of from about 70000 MPa to about 75000 MPa is preferred.The surface of the glass fibre may be coated with a sizing agent. This may be done during the production process.

[0053] Although the density of low-density polyethylene is comparable to or lower than that of polypropylene (from about 0.90 g / cm3to about 0.92 g / cm3) and high-density polyethylene (from about 0.94 g / cm3to about 0.97 g / cm3), the presence of modulus enhancer additives that are denser than the polyolefins conventionally used for plastic pallets, such as polypropylene and / or high-density polyethylene, results in the polymeric composite having a higher density than the conventional compositions used for plastic pallets.

[0054] Accordingly, the polymeric composite preferably has a density of from about 1.00 g / cm3to about 1.15 g / cm3as measured according to

[0055] ISO 1183-1, more preferably from about 1.00 g / cm3to about 1.10 g / cm3.

[0056] The polymeric composite typically has a melt mass-flow rate of from about 0.2 g / 10 min to about 2.0 g / 10 min as measured according to ISO 1133-1 at 190 °C with a load of 2.16 kg, preferably from about 0.40 g / 10 min to about 1.5 g / 10 min.

[0057] The polymeric composite may optionally comprise further polymer processing additives. Suitable polymer processing additives include antioxidants, UV stabilisers, pigments, dyes, coupling agents, antistatic agents, mould release agents, nucleating agents, or any combination thereof.

[0058] A coupling agent may be present to increase the miscibility of the low-density polyethylene based resin and the modulus enhancer additive. A particularly suitable coupling agent for this purpose is maleic anhydride modified polyolefin, such as maleic anhydride modified polyethylene or maleic anhydride modified polypropylene.

[0059] The amount of polymer processing additives depends on the specific type of polymer processing additive, but the polymeric composite may preferably comprise up to about 8 wt.% of polymer processing additives, more preferably from about 0.5 wt.% to about 7.5 wt.%, even morepreferably from about 4 wt.% to about 6 wt.% of polymer processing additives based on the total weight of the polymeric composite.

[0060] As a summary, the sufficient tensile modulus of the polymeric composite ensuring adequate stiffness, combined with the high impact strength of the polymeric composite ensuring high impact resistance, yield a transportation pallet with extended lifetime.

[0061] The transportation pallet may have any dimensions that are conventionally used for pallets. For example, the dimensions of the transportation pallet may comply with ISO standard 6780, as defined by the International Organization for Standardization (ISO).

[0062] The transportation pallet may comprise or essentially consist of the polymeric composite as described herein. It is possible that one or more parts of the transportation pallet comprise or essentially consist of the polymeric composite, whereas one or more other parts are composed of a different material.

[0063] The transportation pallet of the invention can, for instance, comprise a polymeric composite, comprising

[0064] - from about 60 wt.% to about 90 wt.% of low-density polyethylene based resin, preferably from about 65 wt.% to about 87 wt.%, more preferably from about 70 wt.% to about 85 wt.%,

[0065] wherein said low-density polyethylene based resin can comprise about 50 wt.% or more of low-density polyethylene, preferably about 60 wt.% or more, such as about 70 wt.% or more, about 80 wt.% or more, about 90 wt.% or more, or about 95 wt.% or more;

[0066] - from about 10 wt.% to about 30 wt.% of modulus enhancer additive, preferably from about 10 wt.% to about 25 wt.%, more preferably from about 15 wt.% to about 20 wt.%; and

[0067] - from about 0 wt.% to about 10 wt.% of additives (such as polymer processing additives), preferably from about 0 wt.% to about 8 wt.%, morepreferably from about 0.5 to about 7.5 wt.%, even more preferably from about 4 wt.% to about 6 wt.%.

[0068] The invention further provides a polymeric composite comprising - from about 60 wt.% to 90 wt.% based on the total weight of the polymeric composite of low-density polyethylene based resin, wherein the

[0069] low-density polyethylene based resin comprises low-density polyethylene in an amount of 50 wt.% or more by total weight of the low-density polyethylene based resin, and wherein the low-density polyethylene based resin has a melt mass-flow rate in the range of from 0.1 g / 10 min to 50 g / 10 min, as determined according to ISO 1133-1 at 190 °C with a load of 2.16 kg;

[0070] - 10 wt.% to 30 wt.% based on the total weight of the polymeric composite of modulus enhancer additive; and

[0071] - 0 wt.% to 10 wt.% based on the total weight of the polymeric composite of polymer processing additive.

[0072] The features described hereinabove with reference to the polymeric composite in the transportation pallet of the invention equally apply to the polymeric composite of the invention.

[0073] The invention further provides a method of forming a transportation pallet as described herein, comprising

[0074] (i) mixing at least low-density polyethylene based resin and modulus enhancer additive in an extruder to give a polymeric composite.

[0075] (ii) moulding the polymeric composite into transportation pallet or a part of a transportation pallet.

[0076] (iii) if the composite in step (ii) was moulded into part of a transportation pallet, assembling the part of a transportation pallet together with any other parts into a transportation pallet.

[0077] Any polymer processing additives may also be mixed together with low-density polyethylene based resin and modulus enhancer additive in the extruder.In the extruder, the components are melt-mixed in a homogeneous mixture. The compounding temperature in the extruder can be in the range of from about 180 °C to about 300 °C, such as from about 190 °C to about 250 °C. The resulting mixture may be conveyed in the end of the extruder with a pelletiser to pelletise the mixture into processable material for pallet production.

[0078] The invention has been described by reference to various embodiments, and methods. The skilled person understands that features of various embodiments and methods can be combined with each other.

[0079] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0080] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification shouldbe construed as indicating any non-claimed element as essential to the practice of the invention.

[0081] Preferred embodiments of this invention are described herein, including the best mode known to the inventor for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventor intends for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0082] While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one of ordinary skill in the art that various changes and modifications can be made therein without departing from the spirit and scope of the claimed invention.

[0083] The invention will now be illustrated by means of the following, non-limiting, examples.Examples

[0084] Example 1 - preparation of polymer composites

[0085]

[0086] The low-density polyethylene (LDPE) based resin was recycled low-density polyethylene commercially available as “InfiniteFilm LDPE regranulate” from Attero, which contains up to 8 wt.% impurities and 2 to 5 wt.% of polypropylene. The tensile modulus of such resin is 300 to 400 MPa, with the impact strength more than 100 kJ / m2, and the melt mass-flow rate is about 1 g / 10 min under the condition of 190 °C and 2.16 kg.

[0087] The glass fibre was Jushi 508A Chopped Strands made from E6-CR glass, having a filament diameter of 13 pm and a mean average length of 4.5 mm. The glass fibre contains a sizing agent.

[0088] The polymer processing additives were antioxidants and a coupling agent, namely maleic anhydride modified low-density polyethylene.

[0089] The mixing of the composite material was executed with a twin-screw extruder: All the components were fed into the extruder with one single hopper equipped with gravimetrical feeder. The extruder temperature was set at either 190 °C or 250 °C to melt all the components except the modulus enhancer additive and mix the components into homogenous mixture which was conveyed in the end of extruder with a pelletiser to pelletise the mixture into processable material for plastic pallet production and ISO standard tests.

[0090] A comparative composition was prepared as follows. The composition was based on the material of a conventional plastic pallet,comprising a mix of recycled polypropylene and high-density polyethylene with a mix ratio of 10 to 30 wt.% of polypropylene and 70 to 90 wt.% of high-density polyethylene. According to EU standard, the recycled polypropylene and high-density polyethylene also contain up to 6 wt.% of impurities.

[0091] A commercially available plastic pallet with the above-described composition was shredded into flakes. The shredded pallet flakes were fed into the twin screw extruder with one single hopper equipped with gravimetrical feeder. The extruder temperature was set at 190°C to melt the pallet flakes to be conveyed in the end of extruder with a pelletiser to pelletise the mixture into processable material for plastic pallet production ISO standard tests.

[0092] Example 2 - Test results

[0093] Test specimens were made with a BOY injection moulding machine. The polymeric compositions were fed into the hopper of the BOY injection moulding machine with the injection temperature set at 210 °C, and the temperature of the mould was set as 40 °C. The mould is designed with a cavity in accordance with the ISO 527-1 test specimen, therefore the ISO 527-1 test samples were directly fabricated by the injection moulding process.

[0094] The ISO 179-1 impact strength test samples were made via the trimming of ISO 527-1 test samples.

[0095] The ISO 1183-1 density test samples were made via the trimming of ISO 527-1 test samples.

[0096] The ISO 1133-1 melt-mass flow rate samples were the polymeric composite produced in the processable formats.The following properties were determined according in accordance with the indicated ISO standards. The extrusion temperatures are indicated behind each composition, being either 190 or 250 °C.

[0097]

[0098] The density (g / cm3) of the samples was determined according to ISO 1183-1. The measurements were performed in triplicate.

[0099]

Claims

Claims1. A transportation pallet comprising a polymeric composite, comprising- 60 wt.% to 90 wt.% based on the total weight of the polymeric composite of low-density polyethylene based resin, wherein the low-density polyethylene based resin comprises low-density polyethylene in an amount of 50 wt.% or more by total weight of the low-density polyethylene based resin, and wherein the low-density polyethylene based resin has a melt mass-flow rate in the range of from 0.1 g / 10 min to 50 g / 10 min, as determined according to ISO 1133-1 at 190 °C with a load of 2.16 kg;- 10 wt.% to 30 wt.% based on the total weight of the polymeric composite of modulus enhancer additive; and- 0 wt.% to 10 wt.% based on the total weight of the polymeric composite of polymer processing additive.

2. A transportation pallet according to claim 1, wherein the dimensions of the transportation pallet comply with the ISO 6780 standard.

3. A transportation pallet according to claim 1 or 2, wherein the polymeric composite comprises 65 wt.% to 87 wt.% of low- density polyethylene based resin based on the total weight of the polymeric composite.

4. A transportation pallet according to any one of claims 1-3, wherein the polymeric composite comprises 70 wt.% to 85 wt.% oflow-density polyethylene based resin based on the total weight of the polymeric composite.

5. A transportation pallet according to any one of claims 1-4, wherein the low-density polyethylene based resin comprises low-density polyethylene in an amount of 60 wt.% or more based on total weight of the low-density polyethylene based resin, preferably 70 wt.% or more, more preferably 80 wt.% or more, even more preferably 90 wt.% or more, and most preferably 95 wt.% or more.

6. A transportation pallet according to any one of claims 1-5, wherein the low-density polyethylene based resin comprises or essentially consists of recycled low-density polyethylene based resin.

7. A transportation pallet according to claim 6, wherein the recycled low-density polyethylene based resin is according to DKR 310 and / or DKR 350 standard.

8. A transportation pallet according to claim 6 or 7, wherein the recycled low-density polyethylene based resin comprises one or more further polyolefins in an amount of up to 65 wt.% based on total weight of the recycled low-density polyethylene, preferably 0.01 wt.% to 50 wt.%, more preferably 0.01 wt.% to 30 wt.%.

9. A transportation pallet according to claim 8, wherein the one or more further polyolefins are selected from the group consisting of polypropylene, medium-density polyethylene and high-density polyethylene.

10. A transportation pallet according to any one of claims 6-9, wherein the recycled low-density polyethylene based resin comprises non-polyolefin components in an amount of up to 10 wt.% based on total weight of the recycled low-density polyethylene, preferably 0.01 wt.% to 8 wt.%, more preferably 0.01 wt.% to 4 wt.%.

11. A transportation pallet according to any one of claims 1-10, wherein the polymeric composite comprises 10 wt.% to 25 wt.% of the modulus enhancer additive based on total weight of the polymeric composite, preferably 15 wt.% to 20 wt.%.

12. A transportation pallet according to any one of claims 1-11, wherein the modulus enhancer additive is selected from the group consisting of carbon fibre, aramid fibre, natural fibre, talc, calcium carbonate, mica, wollastonite, glass fibre, glass beads, aluminium fibre, aluminium powder, steel fibre, steel powder and any combination thereof.

13. A transportation pallet according to any one of claims 1-12, wherein the modulus enhancer is glass fibre.

14. A transportation pallet according to claim 13, wherein the glass fibre has a mean average length of 0.1 mm to 5 mm, preferably 0.2 mm to 4.8 mm.

15. A transportation pallet according to claim 13 or 14, wherein the glass fibre has a Young’s modulus between 70000 MPa and 75000 MPa.

16. A transportation pallet according to claim 15, wherein the glass fibre is grade E glass fibre.

17. A transportation pallet according to any one of claims 1-16, wherein the polymer processing additive is selected from the group consisting of antioxidant, UV stabiliser, pigment, dye, coupling agent, antistatic agent, mould release agent, nucleating agent and any combination thereof.

18. A transportation pallet according to claim 17, wherein the coupling agent comprises modified polyolefin, preferably maleic anhydride modified polyolefin, more preferably maleic anhydride modified polyethylene.

19. A transportation pallet according to any one of claims 1-18, wherein the polymeric composite comprises up to 8 wt.% of polymer processing additive based on the total weight of the polymeric composite, preferably 0.5 wt.% to 7.5 wt.%, more preferably 4 wt.% to 6 wt.%.

20. A transportation pallet according to any one of claims 1-19, wherein the polymeric composite has an impact strength of 10 kJ / m2to 50 kJ / m2for a notched specimen as measured according to ISO 179-1, preferably 30 kJ7m2to 45 kJ / m2.

21. A transportation pallet according to any one of claims 1-20, wherein the polymeric composite has a tensile modulus of 600 MPa to 2700 MPa as measured according to ISO 527-1, preferably 1000 MPa to 1800 MPa.

22. A transportation pallet according to any one of claims 1-21, wherein the polymeric composite has a tensile strength of 10 MPa to 30 MPa as measured according to ISO 527-1, preferably 15 MPa to 20 MPa.

23. A transportation pallet according to any one of claims 1-22, wherein the polymeric composite has a density of 1.00 g / cm3to 1.15 g / cm3as measured according to ISO 1183-1, preferably 1.00 g / cm3to 1.10 g / cm3.

24. A transportation pallet according to any one of claims 1-23, wherein the polymeric composite has a melt mass-flow rate of 0.20 g / 10 minto 2.0 g / 10 min, as measured according to ISO 1133-1 at 190 °C with a load of 2.16 kg, preferably 0.40 g / 10 min to 1.5 g / 10 min.

25. A polymeric composite as defined in any one of claims 1-24.

26. A method of forming a transportation pallet according to any of the previous claims, comprising(i) mixing at least the low-density polyethylene based resin and the modulus enhancer additive in an extruder to give a polymeric composite;(ii) moulding the polymeric composite into a transportation pallet or a part of a transportation pallet; and(iii) if the composite in step (ii) was moulded into part of a transportation pallet, assembling the part of a transportation pallet together with any other parts into a transportation pallet.

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