Products made from recycled residue in the form of flakes

Abstract

Products formed from recycled residues in the form of flakes. The invention relates to an object formed from recycled material, said object comprising at least in its composition a polyolefin or a mixture of polyolefins as well as fillers of density greater than 1, said object being characterized by a density that varies in its thickness, said density comprising a surface density called "skin", a center density called "core", and in that the ratio core density / skin density is between 0.55 and 0.95.

Description

Title of the invention: Products formed from recycled residues in the form of flakes

[0001] The present invention relates generally to the field of waste recycling. More specifically, the present invention relates to products in the form of solid or hollow 3D objects (also referred to as parts or articles in this application) obtained from waste in the form of shredded or granulated multi-component plastics that have been previously sorted and identified by source, each source being characterized by its raw material composition. In this process, the raw materials are not separated, and the multi-layered or multi-component waste is used directly (without an intermediate step) to manufacture the objects and parts. Previous technique

[0002] Publication FR 2 428 518 presents a process for transforming a thermoplastic synthetic material, in particular thermoplastic synthetic waste, into an object having the workability and processing properties of wood. In this document, the object of the invention described is to propose a process for transforming a thermoplastic synthetic material into a shaped article, in which a pressure-resistant apparatus is not necessary, but rather commercially available, non-pressure-resistant apparatus and dies or molds are used.

[0003] In FR 2 428 518, a process is proposed for transforming a thermoplastic synthetic material in which the synthetic material is subjected to a mixing operation in a sleeve comprising a screw element, is made fluid, is molded, is cooled in the mold and is extracted from the mold, characterized in that the synthetic material feeds an extrusion apparatus without a screen grid and without an extrusion die and is held there until a material is obtained which is made fluid by the increase in temperature, this material containing a gas when it leaves the extrusion apparatus and then passes into a mold which is open at its opposite ends, one of which is connected to the outlet of the extrusion apparatus.

[0004] The process according to FR 2 428 518 can be carried out using any commercially available screw extrusion apparatus, which may be of the adiabatic type or of the conventional type, but from which the pressure-generating elements (normally resulting in pressures of 100-450 kg / cm²), i.e., the sieve pack or heat exchanger and the extrusion die must be removed. The screw-type extruder is thus essentially a screw conveyor, approximately like a Meat grinder. The molding operation, which in the process according to FR 2 428 518 is carried out in a separate phase, must be performed in an open mold. Since the material to be molded is introduced without pressure, ordinary, standard-quality tubes with a round or rectangular cross-section can be used to make, for example, round or rectangular posts or beams. The mold filling pressure is provided in the process according to the invention by the molding gas available in the fluid material to be molded. The molding gas is obtained by adding a blowing agent to the divided synthetic material, intended to feed the extruder, whose threshold temperature is exceeded by the temperature established in the extruder.Suitable blowing agents include, for example, solid granular blowing agents with a threshold temperature of 150-270°C, such as azodicarbonamide (200°C), 3,3'-diphenylsulfone disulfonyl hydrazide (150°C), and 3-[3-oxy-bis(benzenesulfonyl semicarbazide)] (210°C). The proportion of blowing agent can be determined by testing and depends, among other things, on the shape of the final product and the properties of the thermoplastic material. Suitable proportions range from 0.4% to 1.2%, calculated on the weight of the mixture of thermoplastic material and blowing agent.

[0005] In this publication, when a gas is used as a molding gas, for example nitrogen or air, this gas is brought to the extruder after the thermoplastic synthetic material has been made fluid.

[0006] The process according to FR 2 428 518 has many advantages, notably its non-criticality. By using existing control means for commercially available conventional screw extruders, the entire process can be easily controlled. Since an adiabatic extruder has smaller dimensions, this type is preferred because it results in lower costs. Because no sieve pack is used in the screw extruder, there is practically no risk of clogging the apparatus, so the thermoplastic resin material to be processed does not need to be pre-washed or purified. The process according to FR 2 428 518 is also not very critical with regard to the composition of the starting material, to the point that mixtures of different thermoplastic resin materials can be processed satisfactorily.Since there is no established pressure in the apparatus in which the process according to the invention is carried out, the apparatus does not need to meet special requirements, for example with regard to the geometry of the screw. The molds also do not need to meet special requirements with regard to pressure resistance, so standard commercial-grade molds can be used.

[0007] The international application published under number WO2022 / 148841 describes a process for recycling residues in the form of flakes. In this process, flakes are taken, compacted, and fed into a plasticizing tool. In this tool, The glitter is melted, mixed, and the extruded material is injected under high pressure into a mold to form a part. In the described process, the decomposition gases generated by heating and pressurizing the recycled material in the plasticizing tool are used to lubricate the material during its injection into the mold and to compensate for material shrinkage during cooling without the need for additional gas. The mold is then cooled. Finally, the part is extracted from the mold.

[0008] Publication WO2023 / 148259A1 presents an innovative composition aimed at improving the recycling of polyolefins, particularly difficult-to-recycle materials containing aluminum, such as those found in aseptic beverage cartons. Typical cartons comprise approximately 75% cardboard, 20% plastic, and 5% aluminum. The composition seeks to achieve a balance between rigidity and impact resistance, while also being suitable for injection molding, especially for thick-walled articles.

[0009] It comprises four main components: (A) 10 to 50% by weight of recycled polyethylene containing 0.5 to 18% aluminium, ideally low-density polyethylene (LDPE) with increased density due to the aluminium. This component improves thermooxidative stability, crystallinity and tensile strength; (B) 25 to 50% by weight of polypropylene homopolymer with a low content of xylene-soluble compounds, which contributes to the rigidity of the composition; (C) 10 to 30% by weight of a heterophase propylene copolymer, enriched with ethylene or other α-olefin, to improve low-temperature impact and shock resistance; (D) Up to 10% by weight of other additives, such as nucleating agents, antioxidants or UV stabilizers, to optimize properties and processing.

[0010] This innovative composition aims to enhance "PolyAl" (a mixture of polyethylene and aluminum from the recycling of beverage cartons) by combining it with virgin polymers to create materials with improved mechanical and processing properties, suitable for the manufacture of injection-molded objects such as boxes, crates, pallets, and bins.

[0011] The underlying idea is not only to meet the challenges posed by the recycling of polyethylene-aluminium composite materials but also to provide a sustainable solution by increasing the use of recycled materials in new applications, thereby contributing to the circular economy and waste reduction.

[0012] Publication WO2023 / 148259A1 has many advantages; however, it is limited to a recycled aluminum mass content of 18% and combines the use of virgin and recycled resin. Another drawback is related to the density of the aluminum-plastic mixtures for producing thick-walled parts. Objects obtained by the described process are much heavier than objects made of plastic resin, which is often a disadvantage.

[0013] The invention makes it possible to remedy the aforementioned drawbacks. Description of the invention

[0014] One of the aims of the invention is to improve the products and objects obtained by recycling material.

[0015] More particularly, one object of the invention is to offer products (in the form of objects, parts or articles), obtained by recycling materials from waste from different sources.

[0016] Another object of the invention is to offer products and objects obtained by recycling materials which have improved properties compared to existing products and objects.

[0017] In the context of the present invention, the method described in PCT application WO2022 / 148841 can be used to manufacture the objects, for example. Of course, this is not limiting and other methods are possible.

[0018] Within the scope of the present invention and according to embodiments thereof, products obtained from ground or granulated multi-component plastics (generally referred to as "flakes" in the remainder of this description) are proposed in solid or hollow 3D parts, for example with a cross-section ranging from 1 cm² to 600 cm², preferably from 4 cm² to 200 cm², and a length of 0.3 m to 10 m, and preferably from 0.5 m to 6 m. These values ​​are, of course, indicative and not limiting.

[0019] The materials used and present in these glitter flakes are primarily plastic-based, for example thermoplastic resins, mixed with other materials: for example, aluminum or other metals, inks, varnishes, adhesives such as glues, wood, glass, carbon or flax fibers, or other materials of a different nature, and other miscellaneous materials as described in this application. The proportion of plastic materials is in the range of 30% to 95%, preferably 40% to 90% by mass. Examples of such materials are described, for example, in publication WO 2022 / 148841.

[0020] The products according to the invention are themselves considered recyclable because they are reusable after simple grinding into flakes using the process described in publication WO 2022 / 148841, for example. Typically, an object according to the present invention can be recycled and reused in this process. For example, the composition used to form objects according to the present invention may contain approximately 25% to 30% of material from such an object, which is thus directly recycled to reform an object.

[0021] The present invention will be better understood with the aid of the following description of embodiments thereof and of the claims. In these, embodiments of the invention are defined by independent claims, and dependent claims define particular embodiments.

[0022] In embodiments, the invention relates to an object formed from recycled material from at least one first source, said object comprising at least in its composition a polyolefin or a mixture of polyolefins as well as fillers of density greater than 1, said object preferably having a variable density in its thickness, said density comprising a surface density called "skin", a center density called "core", the ratio core density / skin density preferably being between 0.55 and 0.95.

[0023] In embodiments, the core density / skin density ratio preferably between 0.6 and 0.9.

[0024] In embodiments, the object density / skin density ratio is preferably between 0.85 and 0.95.

[0025] In embodiments, the object density / skin density ratio is preferably between 0.87 and 0.93.

[0026] In embodiments, said object comprises materials from at least one first source of recycled materials.

[0027] In embodiments, said source comprises synthetic resin-based materials.

[0028] In embodiments, said source of recycled materials comprises at least the following materials: -) a polyolefin or a mixture of polyolefins with a density preferably less than 1; -) charges including aluminium or glass with a density greater than 1; -) a mass charge ratio greater than 5%.

[0029] In embodiments, the materials used are based on polyethylene or polyolefin mixed with other materials such as metal, inks, varnishes, glues, wood, fiberglass or packaging tubes comprising a barrier layer.

[0030] In embodiments, said object comprises materials from at least one other source or from a plurality of other sources, said other source or plurality of other sources comprising fillers, said fillers comprising aluminium fibres or particles, and / or metals, and / or fibres, and / or inks, and / or adhesives, and / or varnishes, and / or mineral fillers, and / or oils, and / or residues of packaged product and / or washing residues, and / or toothpaste tubes and / or champagne bottle caps and / or car bumpers and / or dashboards.

[0031] In embodiments, a source of material comprises objects according to the present invention which have already been produced, defective or not, which are recycled in this way to reform new objects according to the principles of the present invention.

[0032] In some embodiments, the material source comprises 25% to 30% of these objects already produced.

[0033] In certain execution modes, the object includes a marking. The marking includes, for example, a logo and / or one or more letters and / or one or more numbers, and / or a geometric shape. For example, the marking could be a trademark.

[0034] In embodiments, said object is for example a post, a stake, a profile, a support, a board, a slab, a pallet, a base.

[0035] In embodiments of the invention, ground residues of various products, which are in the form of flakes after grinding, are used as raw materials. Typically, the materials used are primarily thermoplastic resins, for example, polyolefin-based, mixed with other materials: for example, metals such as aluminum, inks, varnishes, adhesives, wood, fiberglass, or other materials, as described in this application. For example, these residues consist of packaging tubes comprising, in particular, an aluminum barrier layer and polyethylene layers. After use, these tubes are ground and form this raw material, which is used without prior separation of the different materials as a source of recycled material. In embodiments, objects according to the present invention are reused as a raw material after grinding, preferably in a proportion of 25% to 30%.Other values ​​are of course possible (less than 25% or more than 30%).

[0036] In embodiments, the glitter may be from a plurality of recycled material sources, for example from at least two recycled material sources.

[0037] In embodiments, a source of recycled materials preferably includes materials based on plastic or synthetic resins, for example mainly based on polyolefin, polyethylene in particular.

[0038] In embodiments, other sources of recycled materials preferably include fillers such as aluminum fibers or particles, metals, fibers, inks, adhesives, varnishes, mineral fillers, oils, packaging tubes including a barrier layer, residues from the packaged product, and washing residues. Other equivalent materials are possible.

[0039] In embodiments, other sources include toothpaste tubes and / or champagne bottle caps and / or car bumpers and / or dashboards.

[0040] In other embodiments, fibers can also be added to the material as an alternative source to increase the rigidity of the parts. Examples of fibers include glass fibers, plant fibers (hemp, etc.) or non-plant fibers, cotton fibers, etc. Any suitable fibers can be used, preferably with a density greater than 1.

[0041] Within the framework of the present invention, in embodiments, the objects made from these sources have a structure comprising a variable density in the thickness of the object, namely: -) a surface density (called "skin density") and a core density (called "core density"). According to the present invention, the skin density is greater than the core density; -) a compacted material density (i.e. the theoretical density of the mixture) approximately equal to the skin density.

[0042] In embodiments, the objects manufactured according to the invention thus contain, for example, in their composition at least the following recycled products: A polyolefin or a mixture of polyolefins with a density of less than 1; Fillers such as aluminium or glass with a density greater than 1 and preferably greater than 2; A mass percentage of fillers greater than 5% and preferably greater than 20%.

[0043] In embodiments, the objects according to the invention have a variable density throughout their thickness, and in particular a core density lower than their surface density. According to the invention, the surface thickness of the object preferably represents 15% of the object's thickness and its density is substantially equal to the density of the compacted material (theoretical density of the mixture). The core thickness preferably represents 70% of the object's thickness and its density is lower than that of the surface.

[0044] According to the invention, in embodiments, the ratio of core density to skin density is between 0.55 and 0.95 and preferably between 0.6 and 0.9.

[0045] In embodiments, the objects according to the present invention are also characterized by the fact that their density remains low despite the presence of fillers such as aluminum or glass in the composition. Thus, according to the invention, the ratio between the density of the object and the density of the skin is between 0.84 and 0.95, and preferably between 0.86 and 0.92.

[0046] According to the invention, in embodiments, the objects have a lightweight core structure characterized by cavities whose size can vary from a few microns to a few millimeters. According to the invention, the core cavity volume ratio is greater than 10% and preferably greater than 15% and advantageously greater than 20%. According to the invention, the volumetric cavity rate in the object is greater than 5% and preferably greater than 8%.

[0047] In embodiments, the manufactured part may be, for example, an object such as a post, stake, profile, support, board, slab, pallet, base, pot, or other equivalent object as described in this application. Brief description of the drawings

[0048] [Fig.1] illustrates the structure of the objects according to the invention and their density as detailed in the present application.

[0049] [Fig-2] illustrates density ratios in the object for different formulations data provided as illustrative examples.

[0050] [Fig.3] illustrates the skin density of the object, the core density of the object and the average density of the object as a function of the mass charge rate.

[0051] [Fig.4] illustrates the volumetric rate of gas bubble at the core of the object and the volumetric rate of gas bubble in the object as a function of the mass charge rate.

[0052] [Fig.5] illustrates the theoretical bending test carried out with samples of stakes according to the prior art and according to the invention.

[0053] [Fig.6] illustrates the curve of evolution of the bending stress in MPa as a function of the deformation of the stake samples.

[0054] [Fig.7] illustrates a comparison of the measured flexural moduli of the stake samples.

[0055] [Fig.8] and [Fig.9] illustrate examples of objects according to the present invention. Detailed description of the invention

[0056] In the context of the present invention, waste plastic objects, cleaned or not, are used directly and ground into flakes with an apparent bulk density of between 0.1 and 2 and preferably between 0.2 and 1.5.

[0057] In the context of the invention, waste (including, but not limited to, plastic objects) from different sources, as indicated above and in the present application, is advantageously used. Mixing waste (including plastics) from different sources in controlled proportions offers numerous advantages, as described in the present application.

[0058] A first advantage of the invention is that it allows for rapid adjustment of the mixture proportions according to the production to be carried out and the desired properties of the product obtained by the process. For example, the invention makes it possible to adjust the object's stiffness modulus, its resistance to stress cracking, its density, its impact resistance, its hardness, or even its thermal resistance by acting on the raw material used. To this end, different recycled waste sources are used. are preferred. As described, a first source essentially comprises materials based on plastic resins. A first advantageously used waste source consists primarily of polyethylene, such as multilayer plastic-aluminum packaging or plastics of different types that do not mix (e.g., PE-PET mix, PP-PET mix). Of course, other equivalent material sources are possible. Another advantageously used source in embodiments of the invention contains metallic and / or fibrous particles, such as aluminum particles and / or glass fibers. According to the invention, another source contains fillers such as aluminum fibers or particles, metals, fibers, inks, adhesives, varnishes, mineral fillers, oils, residues from the packaged product and washing residues, or other equivalent fillers.A non-limiting example of a waste source containing aluminum particles is a toothpaste tube with a multi-layered plastic-aluminum structure. Another non-limiting example is champagne bottle caps. Other sources in the form of fibrous waste include purge materials used in injection molding or waste from the automotive industry such as bumpers and dashboards.

[0059] A second advantage of the invention arising from the use of plastic waste from various sources is an unexpected effect of great interest for the aesthetic quality of the finished objects. It has been observed that certain waste materials or components present in or on the waste and glitter used tend to generate gases during the manufacturing process of the recycled objects. In the plastics processing industry, these gases, resulting from an unintentional decomposition mechanism under the effect of heat, are usually separated from the resin before the object is manufactured. This separation step is implemented in particular in so-called "compounding" processes, which allow the formulation of thermoplastic resins by adding fillers, for example, or by blending polymers.In these compounding processes, degassing is carried out during or after mixing in order to extract the gases produced by the decomposition.

[0060] In the invention, gases, or at least a portion thereof, resulting from the decomposition process have a beneficial effect: a first beneficial effect is the reduction of the viscosity of the product injected into a mold, because these decomposition products are in a liquid state when subjected to the high pressures in the plasticizing and injection molding tool. These pressures are typically between 100 bar and 1000 bar. These decomposition products remain in a liquid state when the pressure exceeds a few bars, for example, approximately 5 bar. Consequently, there is a significant advantage to retaining these decomposition products in the processed product because their low viscosity in the liquid state allows them to lubricate the polymer chains and reduce the viscosity of the product. significantly reduces the viscosity of the material. This effect has a double benefit, namely, on the one hand, the reduction of energy consumed for the manufacture of said recycled objects and, on the other hand, the possibility of manufacturing long objects with a reduced cross-section (such as stakes, posts, profiles etc).

[0061] A second beneficial effect of the decomposition products is related to the change of state from liquid to gas as soon as the pressure decreases sufficiently during manufacturing. Consequently, and contrary to prior art publications that propose adding blowing agents, the invention advantageously uses the decomposition products, which transform into gas when the injected object cools: the expansion force generated by the gas is then used to compensate for the shrinkage of the molded material during cooling. This results in molded objects of high visual quality and high dimensional accuracy.

[0062] According to [Fig. 1], an object 1 according to the present invention is illustrated schematically in a rectangular shape by way of non-limiting example in cross-section. This object 1 is schematically represented in two parts: a central part 101, which is the so-called "core" part according to the present invention, having a surface area "S2", a density "d2", and a thickness "c". A peripheral part 102, which is the so-called "skin" part according to the present invention, having a surface area "S1", a density "d1", a thickness "s", the total thickness of the object being "t".

[0063] Object 1 according to embodiments of the present invention is defined by the following technical characteristics: -) the skin thickness "s" is approximately 15% of the total thickness "t"; -) The core thickness "c" is approximately 70% of the total thickness "t". These proportions are non-limiting examples and these values ​​may vary.

[0064] According to the present invention and in a known manner, to determine the density of object 1, it can be immersed in a container filled with water. Once the object is immersed, the volume of water displaced is measured, and the volume of the object is determined. The object is then weighed, and its density can subsequently be determined. Other equivalent methods are, of course, possible within the scope of the present invention.

[0065] Table 1 below illustrates examples of objects made from different sources of recycled materials according to the present application and the density of the object as a function of the raw materials that compose it, said raw materials being contained in the sources used. These objects 1 to 11 (first column of Table 1, corresponding for example to object 1 of Fig. 1) are shown in Table 2 and on Fig. 2 (points referenced 1 to 11) where the measured values ​​for each object 1-11 are shown as the ratio of object density to skin density (along the abscissa X) and the ratio of core density to skin density (along the ordinate Y).

[0066] [Tables 1] Ref PE PP Other PS PET Rubber Aluminum Fiber Aluminum+FV Formulation Density Estimated Density (dl) 1 41.7% 25.6% 6.4% 0.0% 5.0% 0.0% 9.3% 12.0% 21.3% 1.08 1.07 2 36.8% 15.0% 20.0% 5.0% 0.0% 0.0% 8.2% 15.0% 23.2% 1.08 1.08 3 51.4% 17.5% 0.0% 0.0% 5.4% 0.0% 8.2% 17.5% 25.7% 1.12 1.10 4 40.9% 6.4% 27. 0% 0.0% 0.0% 1.6% 9.1% 15. 0% 24.1% 1.08 1.09 5 40. 9% 24. 0% 4.4% 0.0% 5.0% 1.6% 9.1% 15. 0% 24.1% 1.11 1.09 6 54. 0% 15. 0% 0.0% 0.0% 4.1% 0.0% 12. 0% 15. 0% 27.0% 1.13 1.11 7 49. 0% 30. 0% 0.0% 0.0% 0.0% 0.0% 11. 0% 10. 0% 21.0% 1.06 1.06 8 48. 6% 17. 5% 0.0% 0.0% 4.1% 0.0% 12. 4% 17. 5% 29.9% 1.16 1.14 9 48. 2% 0.0% 23. 0% 0.0% 3.0% 0.0% 10. 8% 15. 0% 25.8% 1.11 1.10 10 40. 9% 24. 0% 6.0% 5.0% 0.0% 0.0% 9.1% 15. 0% 24.1% 1.09 1.09 11 40. 9% 0.0% 20. 0% 0.0% 10. 0% 0.0% 9.1% 20. 0% 29.1% 1.18 1.13

[0067] [Tables2] Ref Density of object D Core density De Skin density Dp Dc / Dp D / Dp Bubble flight rate object Bubble flight rate core 1 0.93 0.85 1.04 0.82 0.90 0.10 0.18 2 1.00 0.83 1.11 0.75 0.91 0.09 0.25 3 1.00 0.82 1.11 0.74 0.90 0.10 0.26 4 1.03 0.82 1.15 0.71 0.90 0.10 0.29 5 0.94 0.69 1.06 0.65 0.88 0.12 0.35 6 1.00 0.85 1.10 0.77 0.91 0.09 0.23 7 1.03 0.87 1.13 0.77 0.91 0.09 0.23 8 1.02 0.84 1.11 0.75 0.91 0.09 0.25 9 1.00 0.97 1.14 0.86 0.88 0.12 0.14 10 0.98 0.87 1.08 0.81 0.91 0.09 0.19 11 1.01 0.86 1.14 0.76 0.89 0.11 0.24

[0068] For example, in the first row of [Table 1], object "1" is made of flakes comprising 41.7% PE, 25.6% PP, 6.4% other materials, 0% PS, 5.0% PE, 0% Rubber, 9.3% aluminum, and 12% glass fibers. These raw materials are contained in the recycled material sources used to feed a production machine. The formulation density is 1.08 and the estimated density is 1.07. This object "1" is also found in [Table 2] (rounded values) and in [Fig. 2] with an object density / skin density (X-axis) of 0.9 and a core density / skin density of 0.82.

[0069] The other lines are read in the same way, with the proportion for each material forming the flakes of the raw material and the representation of the object obtained in [Table 2] and on the graph in [Fig. 2]. From these multiple measurements on objects 1-11 formed from the different compositions of [Table 1] above, the intrinsic characteristics of the products or objects according to the invention, illustrated in [Fig. 2], can be deduced: -) the core density / skin density ratio is approximately between 0.55 and 0.95, preferably between 0.6 and 0.9, and preferably between 0.65 and 0.86; -) the ratio of object density / skin density is approximately between 0.84 and 0.95, and preferably between 0.86 and 0.92 and preferably between 0.88 and 0.918; -) the skin density is greater than 1.

[0070] The various mixtures preferably have a filler content (aluminium + fibreglass, Alu + FV column in [Table 1] above) greater than 5% and preferably greater than 20%. Thus, the minimum density of the formulations is greater than 1, and preferably greater than 1.05. From a given object, the density of the formulation can be estimated a posteriori by measuring the filler content (Aluminum + Fiberglass) of the object. The filler content is obtained by pyrolysis of the object (at approximately 600°C-700°C). The mass filler content (Te) is determined by dividing the mass of the fillers by the mass of the object: Te = m(fillers) / m(object) Considering a charge density De = 2.6 and a matrix density Dm = 0.92, we can estimate the density of the formulation Df: 1 / Df = (1-Tc) 1 / Dm + Te 1 / Dc Example: Te = 0.23 1 / Df = (1-0.23)xl / 0.92 + 0.23x1 / 2.6 = .925 Df = 1.08

[0071] The estimation of Df can be used to determine whether an object exhibits the characteristics of the objects according to the invention.

[0072] A surprising property of the objects according to the present invention is illustrated in [Fig.3]. On this [Fig.3], the variation in density of the object, the skin and the central part (core) of the object is shown as a function of the charge level.

[0073] Surprisingly, a very small variation in the density of the object, the density of its skin, and the density of its core is observed as a function of the loading rate. This very small dependence of the object's density on the loading rate offers numerous advantages. It allows the rigidity of the objects to be adjusted by changing the loading rate without significantly altering their mass.

[0074] A significant density difference is also observed between the skin and the core of the object. In the description of the invention, it has been arbitrarily assumed (and by way of non-limiting example) that the skin thickness represents 15% of the total thickness and that the core thickness represents 70% of the thickness. The skin covers the entire surface of the object; therefore, the skin is found twice within the object's thickness, once on each face. The core is completely enclosed within the object by the skin (see [Fig. 1]). The density difference between the skin portion 20 and the core portion 10 is a particularly interesting property. In [Fig. 1], it can be seen that the core portion 10 is on average 25% less dense than the skin portion 20, which allows for a lighter object with very good mechanical properties (strength). observed in the core part 10 cavities visible to the naked eye which explain the lower density, while these cavities are not visible to the naked eye in the skin part 20.

[0075] Figure 4 illustrates the volumetric percentage of cavities (or bubbles) in the core (see the last two columns of Table 2) as a function of the charge level in the object. It can be seen that the volumetric percentage of cavities in the core does not depend on the charge level and averages approximately 24%. By measuring the skin density Dp and a core density De, the core cavity rate Tv can be estimated using the following formula (assuming that the density in the formulation is equal to the skin density): Tv = 1 - Dc / Dp Example 1 (see line 2 of _ J, Table 2 B _ J. Core density measured: Dc = 0.83 Dp=l,ll Tv = 1-0.83 / 1.11 = 0.25 In this example, the volumetric rate of cavity to heart is therefore approximately 25%. Example 2 (see line 5 of _ J, Table 2 1); Core density measured: Dc = 0.69 Dp=l.06 Tv = 1-0.69 / 1.06 = 0.35 In this example, the volumetric rate of cavity to heart is therefore approximately 35%.

[0076] A comparative study between stakes according to the present invention and stakes from the prior art (referred to as "Ref. 1" and "Ref. 2") is discussed below, said stakes being of the same dimensions and having a square cross-section. This study focuses on a 3-point bending and density measurement between these different types of stakes.

[0077] Method: The bending test determines the deformation capacity of a material on two supports with the force applied at mid-distance. A standardized specimen is subjected to a deformation, or deflection, at a constant rate of deformation, and the force exerted by the specimen is measured. This test allows for the characterization of intrinsic and extrinsic properties of the material under study. Figure 5 illustrates the basic setup of the test. Samples 20 cm long and with a 2 cm x 2 cm square cross-section are cut from each stake provided. The experimental conditions are: Distance between supports: 150 mm, preload: IN, preload rate: 5 mm / min, test rate: 10 mm / min, breaking strength: 80% of Fmax, maximum deformation: 118 mm.

[0078] Fig. 6 illustrates the comparative results of the measurements carried out on the samples of stakes, i.e. the stress in MPa in relation to the deformation. A very clear difference can be observed between the "Ref. 1 and 2" stakes (from the prior art) and the "Replace® 1 and Replace® 2" stakes according to the invention. For the Ref. 1 and 2 stakes, a stress of up to 21 MPa and 23 MPa, respectively, results in a deformation of approximately 15% and 21%, respectively. For the Replace® stakes, a stress of approximately 36 MPa results in a deformation of only about 5%.

[0079] Figure 7 illustrates a comparison of the flexural moduli of the prior art stakes Ref. 1, Ref. 2, and the Replace® 1 and Replace® 2 stakes. As can be seen, the moduli of the Replace® 1 and 2 stakes are much higher than those of the Ref. 1 and 2 stakes according to the values ​​shown in Figure 7. For example, the Replace® stakes have a flexural modulus almost three times higher than the Ref. 1 and 2 stakes. This means that the Replace® stakes are more rigid and will be less prone to degradation under bending stress.

[0080] The objects 1 according to the invention are preferably elongated, solid or hollow, such as vine stakes, signposts, profiles, or other similar objects. Non-limiting examples of such objects 1 are schematically illustrated in [Fig. 8], which shows successively (from the first drawing at the top left to the last drawing at the bottom right): a stake with a square cross-section, a circular stake, a board, a cross profile, another profile, an angle profile, a "T" profile, and a "U" profile. Of course, these are illustrative examples, and other shapes and profiles are possible within the scope of the present invention and as described in this application. For example, [Fig. 9] illustrates other examples, such as (from top left to right): grass pavers, a pallet, stake bases, and pots. Furthermore, the board in [Fig.[8] includes a marking 2 in the form of a four-pointed star which schematically illustrates the marking according to the present invention. As explained above, the marking 2 may have any suitable shape and is not limited to the star shown in [Fig. 8].

[0081] In embodiments of the invention, the objects produced may include surface markings, for example a logo, a name or a combination thereof, letters and / or numbers, a trademark, which may be incorporated into the mold. This feature then allows for traceability of the objects and / or verification of their origin.

[0082] The execution methods described are given by way of illustration and should not be considered limiting. Other execution methods may employ means equivalent to those described, for example. The execution methods may also be combined with each other depending on the circumstances, or means used in one method may be used in another method.

Claims

Demands

1. Article (1) formed of recycled material from at least one first source, said article (1) comprising at least in its composition a polyolefin or a mixture of polyolefins and fillers of density greater than 1, said article (1) being characterized by a density that varies in its thickness, said density comprising a surface density referred to as "skin density", a center density referred to as "core density", and in that the ratio of core density to skin density is between 0.55 and 0.

95.

2. Object (1) according to claim 1, wherein the core density / skin density ratio is between 0.6 and 0.

9.

3. Object (1) according to any one of the preceding claims, wherein the ratio of object density to skin density is between 0.85 and 0.

95.

4. Object (1) according to any one of the preceding claims, wherein the ratio object density / skin density is between 0.87 and 0.

93.

5. Subject matter (1) according to any one of the preceding claims, wherein said source comprises synthetic resin-based materials.

6. Subject matter (1) according to the preceding claim, wherein the source of recycled material comprises at least the following materials: a polyolefin or a mixture of polyolefins of density less than 1; fillers comprising aluminium or glass of density greater than 1; a mass percentage of fillers greater than 5%.

7. Subject matter (1) according to any one of claims 5 to 6, wherein the materials used are based on polyethylene or polyolefin mixed with other materials such as metal, inks, varnishes, glues, wood, glass fibers or packaging tubes comprising a barrier layer.

8. Subject matter (1) according to any one of claims 5 to 7, said subject matter (1) comprising materials from at least one other source or a plurality of other sources, said other source or plurality of other sources comprising fillers, said fillers comprising aluminium fibres or particles, metals, fibres, inks, adhesives, varnishes, mineral fillers, oils, residues of the packaged product and washing residues, tubes of

9.

10.

11.

12.

13. toothpaste and / or champagne bottle caps and / or car bumpers and / or dashboards. Object according to any one of the preceding claims, wherein one of the sources of materials is an object according to any one of the preceding claims previously produced. Object according to the preceding claim, wherein said source forms 25% to 30% of the total material source. Object according to one of the preceding claims, said object comprising a marking. Subject matter according to the preceding claim, said marking being a logo and / or a letter and / or a number and / or a word and / or a geometric shape. Object (1) according to any one of claims 5 to 12, said object being a post, a stake, a profile, a support, a board, a slab, a pallet, a base, a pot.

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