METHOD FOR RECYCLING FLAKE-LIKE WASTE PRODUCTS

Description

[0001] The present invention relates to the field of waste recycling. More specifically, the present invention relates to a process for transforming a raw material in the form of ground or granulated multi-component plastics into solid or hollow 3D parts without requiring prior sorting of the raw material. Previous technique

[0002] French publication FR 2 428 518 describes a process for transforming a thermoplastic synthetic material, particularly unsorted thermoplastic synthetic waste, into an article 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 pressure-resistant equipment is not required, but rather commercially available, non-pressure-resistant equipment, dies, or molds are used.

[0003] In FR 2 428 518, a process is proposed for transforming a thermoplastic synthetic material, in particular unsorted thermoplastic synthetic waste, into an article having the working and processing properties of wood, 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 or conventional type, but from which the pressure-generating elements (normally resulting in pressures of 100-450 kg / cm²) must be removed, i.e., the screen pack or heat exchanger and the extrusion die. The screw extruder is thus essentially a screw conveyor, roughly like a meat grinder. The molding operation, which in the process according to FR 2 428 518 is carried out in a separate stage, must be performed in an open mold. Since the material to be molded is introduced without pressure, ordinary, standard-quality tubes with round or rectangular cross-sections can be used to make, for example, round or rectangular posts or beams.In the process according to the invention, the mold filling pressure is supplied 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 yield temperature is exceeded by the temperature established in the extruder. Suitable blowing agents are, for example, solid granular blowing agents having a yield temperature of 150-270°C, such as azodicarbonamide (200°C), 3,3'-diphenylsulfone disulfonyl hydrazide (150°C), and β-β-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 using a gas 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 low sensitivity. Using existing control means for commercially available standard screw extruders, the entire process can be easily controlled. Since an adiabatic extruder is more compact, this type is preferred due to its lower cost. Because no sieve pack is used in the screw extruder, there is virtually no risk of clogging, and therefore 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 sensitive to the composition of the starting material; in fact, unsorted mixtures of different thermoplastic resin materials can be processed successfully.Since no pressure is established 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 screw geometry. The molds also do not need to meet special requirements with regard to pressure resistance, so standard commercial-grade molds can be used. GB2213763A describes another known prior art. Description of the invention

[0007] One of the aims of the invention is to improve known processes.

[0008] More specifically, one aim of the invention is to provide a process enabling the recycling of materials from waste.

[0009] Within the scope of the present invention and according to embodiments thereof, a process and a production unit have been developed for transforming ground or granulated multi-component plastics (generally referred to as "flakes" in the remainder of this description) into solid or hollow 3D parts, for example with a cross-section between 1 cm² and 1,600 cm², preferably between 4 cm² and 200 cm², and a length from 0.3 m to 10 m, and preferably from 0.5 m to 6 m. These values ​​are, of course, indicative and not limiting.

[0010] The materials used and present in these ground or granulated products are primarily plastic-based, mixed with other materials such as aluminum or other metals, inks, varnishes, adhesives, wood, fiberglass, or other materials as described in this application. The plastic content is approximately 30% to 100%, preferably 40% to 90% by volume.

[0011] In the context of the present invention, the extruded material is injected under high pressure, for example, in the range of 50 bar to 2000 bar, preferably between 100 bar and 1500 bar. This high pressure allows for a long flow length in the mold, which is facilitated by lubrication of the material as explained below.

[0012] The technical innovations of the process allow this transformation to be continuous at flow rates between 0.05m³ / h and 2m³ / h and preferably between 0.1m³ / h and 1m³ / h, and therefore at production costs lower than the production costs of conventional plastic extrusion and injection processes.

[0013] The products manufactured by the process according to the invention are themselves considered recyclable because they can be reused through the same process after simple grinding to form flakes.

[0014] The present invention will be better understood with the aid of the following description of embodiments thereof and the claims. In these claims, embodiments of the invention are defined by independent claims, and dependent claims define particular embodiments.

[0015] According to embodiments of the invention, ground-up residues from various products are used as raw material. Typically, the materials used are primarily polyolefin-based, mixed with other materials such as metals like aluminum, inks, varnishes, adhesives, wood, fiberglass, or other materials. For example, these residues consist of packaging tubes with a barrier layer. These tubes are ground to form this raw material, which is used without prior sorting.

[0016] In the context of the present invention, the extruded material is injected under high pressure, for example from 50 bar to 2,000 bar as described above. This high pressure allows for a long flow path within the mold, which is facilitated by the lubrication of the material resulting from this high pressure.

[0017] According to another aspect of the present invention, the process is carried out without degassing the extruded material or with partial degassing, the aim being to utilize the gases generated by the material. Indeed, in the prior art, it is common practice to add a gas to the mold or specific foaming agents to the extruded material to compensate for material shrinkage during cooling in the mold. In the context of the present invention, it was surprisingly discovered that this addition of gas or agents could be dispensed with, and that it was possible instead to take advantage of the presence of certain materials in the residues, which themselves generate gases when heated for extrusion, and use these gases to prevent shrinkage. For example, gases can be generated by inks and / or varnishes and / or adhesives and / or other products present in or on the material used to form the glitter.

[0018] In another aspect of the invention, fibers can also be added to the material to increase the rigidity of the parts produced by the process. This addition can be made at different times (such as at the beginning or end of extrusion) as described below, and the fibers can be, for example, glass fibers, plant fibers (hemp, etc.), cotton fibers, etc.

[0019] In embodiments, the invention relates to a process for recycling residues in the form of flakes containing plastic-based materials, characterized in that it comprises the following steps: We take glitter; we compact the glitter and feed it into a plasticizing tool; we melt and mix the glitter in the plasticizing tool; we inject the extruded material under high pressure into a mold to form a part; we use the decomposition gases generated by heating and pressurizing the recycled material in the plasticizing tool to lubricate the material during its injection into the mold and to compensate for material shrinkage during cooling without the addition of extra gas; we cool the mold; we extract the part from the mold.

[0020] In embodiments, the glitter may be derived from at least two recycled material sources.

[0021] In some execution modes, a first source generates decomposition gases preferably at a temperature above 60°C.

[0022] In embodiments the first source preferably includes materials based on plastic resins.

[0023] In some embodiments, the second source preferably contains fillers such as aluminium fibres or particles, metals, fibres, inks, adhesives, varnishes, mineral fillers, oils, residues from the packaged product and washing residues. Other equivalent materials are possible.

[0024] In some execution modes the second source includes toothpaste tubes and / or champagne bottle caps and / or car bumpers and / or dashboards.

[0025] In some execution modes, glitter from different sources is preferably fed simultaneously to an inlet of the laminating tool.

[0026] In some execution modes, glitter from different sources is preferably fed successively into the laminating tool.

[0027] In some execution modes, glitter from different sources is preferably fed successively into the laminating tool.

[0028] In some execution modes, the apparent density of the glitter is preferably between 0.1 and 2.

[0029] In some execution modes, the molten material is injected into a mold preferably at a flow rate of 0.1m³ / h to 10m³ / h.

[0030] In some execution methods, the molten material is injected into a mold under a pressure preferably in the range of 50 bar to 2000 bar.

[0031] In some execution modes, partial degassing of the extruded material is carried out.

[0032] In some execution methods, the part is degassed after it has been extracted from the mold.

[0033] In embodiments the invention relates to a part obtained according to a process as defined in this application.

[0034] In some embodiments, the resulting part comprises materials from at least one recycled material source.

[0035] In some embodiments the source includes materials based on synthetic resins.

[0036] In embodiments the materials used are for example mainly based on polyethylene or polyolefin mixed with other materials such as metal, inks, varnishes, glues, wood, fiberglass or packaging tubes including a barrier layer.

[0037] In some embodiments the second source includes fillers such as aluminium fibres or particles, metals, fibres, inks, adhesives, varnishes, mineral fillers, oils, residues of packaged product and washing residues, toothpaste tubes and / or champagne bottle caps and / or bumpers and / or automobile dashboards.

[0038] In some execution modes the resulting part is for example an object such as a post, a stake, a profile, a support, a board or another equivalent object. Brief description of the drawings

[0039] There figure 1 illustrates a block diagram of one embodiment of the invention. figure 2A illustrates an example of an object obtained by the process according to the invention and the figures 2B to 2E illustrate examples of cuts perpendicular to the longitudinal axis of said object. Detailed description of the invention

[0040] In the context of the present invention, waste plastic objects, cleaned or uncleaned, are directly used, ground into flakes with a bulk bulk density between 0.1 and 2, and preferably between 0.2 and 1.5. Due to their low bulk density, it is difficult to directly use these recycled material flakes in conventional thermoplastic resin extrusion or injection processes. The process developed according to the invention therefore preferably includes a first compaction or forcing phase of the recycled material flakes to increase their bulk density when they are fed into the plasticizing process.

[0041] The invention advantageously utilizes waste plastic objects from different sources. Mixing plastic waste from different sources in controlled proportions offers numerous advantages, as described in this application.

[0042] A primary advantage of the invention is that it allows for rapid adjustment of the mixture proportions according to the production requirements 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, stress cracking resistance, density, impact resistance, hardness, or thermal resistance by modifying the raw material used. To this end, different sources of recycled waste are preferred. In the process, the primary source consists mainly of plastic resin-based materials. One advantageously used primary waste source consists mainly of polyethylene, such as multilayer plastic-aluminum packaging or plastics of different types that do not mix (e.g., PE-PET, PP-PET mix). Of course, other equivalent primary sources of materials are possible.A second source advantageously used in embodiments of the invention contains metallic and / or fibrous particles, such as aluminum particles and / or glass fibers. According to the invention, the second 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 second waste source containing aluminum particles is a toothpaste tube with a multilayer plastic-aluminum structure. Another non-limiting example of a second source is champagne bottle caps. As a source of fibrous waste, purging materials used in injection molding or waste from the automotive industry, such as bumpers and dashboards, can be used.

[0043] A second advantage of the invention, stemming from the use of plastic waste from various sources, is an unexpected effect of great interest both for the manufacturing process itself and 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 tend to generate gases during the manufacturing process. In the plastics processing industry, these gases, resulting from an unintentional decomposition mechanism under the influence of heat, are typically separated from the resin before the object is manufactured. This separation step is implemented particularly in so-called "compounding" processes, which allow for the formulation of thermoplastic resins by adding fillers, for example, or by creating polymer blends.In these compounding processes, degassing is carried out during or after mixing in order to extract the gases resulting from decomposition.

[0044] In the process according to the invention, the aim is, on the contrary, to retain these gases, or at least a portion of them, resulting from the decomposition process for the beneficial effect they provide. A primary benefit is the reduction of the viscosity of the product injected into the 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 finished product because their low viscosity in the liquid state allows them to lubricate the polymer chains and significantly reduce the material's viscosity.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).

[0045] The 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. Consequently, and contrary to prior art publications that propose adding blowing agents, the invention advantageously utilizes 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, even though the cycle time is greatly reduced and simplified.

[0046] In the process according to the invention, the process preferably includes an initial step of forcing the flakes of recycled objects; the forcing step having the effect of increasing the apparent density in the solid state of the flakes at the time of feeding into the plasticizing and mixing tool.

[0047] The process uses flakes from at least one source, or a controlled mixture of flakes from at least two different sources, to adjust the properties of the injected material according to the intended use of the manufactured object. A single source may be sufficient to form an object with the desired characteristics, or it may be necessary to use different material sources.

[0048] When using more than one source, one method is to simultaneously feed glitter from different sources into the laminating tool.

[0049] A second method involves successively feeding each source of glitter into the laminating tool. This method allows for precise dosing of each product at the optimal point within the laminating unit. For example, it can be advantageous to incorporate a recycled product containing fibers into a first recycled product that is already melted in order to limit fiber degradation.

[0050] A third method consists of a combination of the first and second methods when the number of sources is greater than two. For example, products 1 and 2 (sources 1 and 2) could be fed simultaneously at the input of the laminating tool, and product 3 (source 3) could be fed further downstream in the laminating tool. Of course, this is a non-limiting example, and in another embodiment, only one source could be fed at the tool's input, with the other two sources fed further downstream. Therefore, multiple combinations are possible within the scope of the present invention.

[0051] In the process according to the invention, the plasticizing tool allows for the incorporation, mixing, and melting of recycled products from at least one source to ultimately obtain a homogeneous molten material ready for injection. During the process according to the invention, the decomposition products are kept in a liquid state within the mixture during the plasticizing operation by maintaining a pressure in the device above 5 bar after melting.

[0052] In the process according to the invention, the pressure on the molten material is at least 5 bar during the transfer of the material from the plasticizing unit before injection.

[0053] In the process according to the invention, the molten material is injected into a mold at a flow rate of 0.1 m³ / h to 10 m³ / h, and advantageously from 0.5 m³ / h to 5 m³ / h. Due to the high flow rate during injection, the filling time is short, and the pressure within the material during mold filling remains above 5 bar. Consequently, the decomposition products remain in a liquid state and act as a lubricant, reducing the pressure required to fill the cavity. Thanks to this phenomenon, the invention allows the molding of objects with long flow lengths and small cross-sections.

[0054] In the process according to the invention, cooled molds are filled. After injection, the recycled material, upon cooling within the mold cavity, solidifies, causing a decrease in volume and consequently a decrease in pressure within the material. This pressure reduction allows the decomposition products to transition from a liquid to a gaseous state and generate a "core foaming pressure" during the cooling and solidification of the object. This foaming pressure creates cavities distributed throughout the core of the object, in the central portion, while the peripheral portion is devoid of such cavities. According to the invention, the density of the central portion of the object is significantly lower than the density of the peripheral portion, which provides numerous advantages in terms of mass and performance properties of the object obtained by the process.Another advantage of the invention is the production of recycled parts with good visual quality due to their surface condition and high dimensional accuracy due to the compensation of shrinkage thanks to the "core foaming" effect.

[0055] According to a preferred embodiment of the invention, the process is used to manufacture elongated solid or hollow objects such as vine stakes, signposts, profiles, or other similar objects. Examples in side view and in sections perpendicular to the longitudinal axis are illustrated in the figures 2A to 2E which show the profiles of these parts 10. Of course, these are illustrative examples and other shapes and profiles are possible within the scope of the present invention.

[0056] One advantage of the process according to the invention is that the objects produced do not have burrs and are directly usable.

[0057] In general, according to the invention, the process for recycling residues in the form of flakes containing materials based on plastic resins mixed with other materials, such as metals, fibers, inks, adhesives, varnishes, mineral fillers, oils, residues from the packaged product and washing residues, comprises the following steps: We take glitter; we compact the glitter, melt and mix it in an extruder (as a mixing and plasticizing tool); we inject the extruded material under high pressure into a mold to form a part; we use the decomposition gases generated by heating and pressurizing the recycled material in the toolplasticizing to lubricate the material when it is introduced into the mold and to compensate for material shrinkage during cooling without additional gas supply; the mold is cooled; part 10 is extracted from the mold.

[0058] According to some embodiments, the method according to the invention comprises at least the following steps: Use of at least two sources of recycled material; a first generating decomposition products at a temperature above 60°C and preferably above 80°C; and a second containing fillers such as aluminum fibers or particles. Transformation of the waste into flakes with an apparent density between 0.1 and 2; feeding of the flakes from the respective sources in a controlled proportion to obtain a recycled product with the desired properties (e.g., stiffness, stress cracking, density, impact resistance, hardness, heat resistance, appearance). Forcing of the flakes in the solid state to increase their apparent density. Plasticization and mixing of the recycled material using an extruder; the decomposition products are retained by pressure in the extruder exceeding Sbar when the material is molten. Injection of the molten material into a mold at a flow rate of 0.1 m³ / h to 10 m³ / h and advantageously from 0.5 m³ / h to 5 m³ / h. Possible compaction phase after injection. Cooling of the molded part 10 in the mold: the pressure in the mold decreases, the decomposition products change state (liquid - gas), the pressure generated by the decomposition gases compensates for the shrinkage of the cooling material. Demolding of the molded part 10, which has no sink marks or surface defects.

[0059] According to embodiments of the present invention, a degassing phase is optionally carried out on the objects after the molded part or object has been manufactured. This degassing phase has the effect and advantage of limiting the emission of gases and odors during the object's lifespan. The degassing phase is carried out, for example, by storing the molded objects in an enclosure with a temperature between 40°C and 100°C, and preferably between 60°C and 80°C, for a period of between 8 and 72 hours, and preferably between 12 and 48 hours. EXAMPLES

[0060] Tables 1 to 6 below show examples of compositions of ground materials used in the process according to the invention for thirteen and eight trials, respectively. Tables 1 to 3 illustrate the detailed composition, volume composition, and results for trials 1 to 13bis, respectively. Tables 4 to 6 illustrate the detailed composition, volume composition, and results for trials A to H, respectively. Table 1 Test No. HDPE Post-Consumer Colored Bottle Toothpaste tubes Champagne capsule, aluminum, 70 microns thick (total thickness 130 microns) PP derived from extrusion purges of recycled materials Reinforcing fiber 1 65% 22% 13% 1bis 75% 25% 2 65% 22% 13% 2bis 75% 25% 3 22% 65% 13% 3bis 25% 75% 4 22% 65% 13% 4bis 25% 75% 5 87% 13% 5bis 100% 6 65% 22% 13% 6bis 75% 25% 7 22% 65% 13% 7bis 25% 75% 8 87% 13% 8bis 100% 9 52% 35% 13% 9bis 60% 40% 10 35% 52% 13% 10bis 40% 60% 11 36% 54% 11bis 40% 60% 12 17% 70% 13% 12bis 20% 80% 13 70% 17% 13% 13bis 80% 20% Table 2 Test No. Aluminum part Part PE (PERD, PEBD, LIN....) Part PP Adhesives / Inks / Varnishes Fiber Various materials pollution 1 1.2% 81.0% 4.3% <1% 13.0% 1bis 1.4% 93.0% 5.0% <1% 0.0% 2 3.5% 59.0% 20.0% <1% 13.0% 4.4% 2bis 4.1% 67.9% 23.0% <1% 0.0% 5.0% 3 1.2% 18.7% 54.0% <1% 13.0% 13.0% 3bis 1.4% 21.3% 62.0% <1% 0.0% 15.0% 4 3.5% 79.0% 4.3% <1% 13.0% 4bis 4.1% 90.0% 5.0% <1% 0.0% 5 4.7% 75.0% 5.0% <2% 13.0% 5bis 5.5% 86.0% 6.0% <2% 0.0% 6 11.8% 75.0% <1% 13.0% 6bis 13.5% 86.0% <1% 0.0% 7 35.0% 51.0% <2% 13.0% 7bis 40.4% 58.0% <2% 0.0% 8 46.8% 39.0% <2% 13.0% 8bis 53.8% 45.0% <2% 0.0% 9 2.8% 44.4% 24.4% <1% 13.0% 7.0% 9bis 3.3% 51.0% 28.0% <1% 0.0% 8.0% 10 2.8% 79.1% 4.0% <1% 13.0% 0.0% 10bis 3.3% 91.0% 5.0% <1% 0.0% 0.0% 11 2.0% 30.8% 37.9% <1% 13.0% 10.8% 11bis 2.2% 34.0% 42.0% <1% 0.0% 12.0% 12 38.4% 44.0% 3.0% <2% 13.0% 12bis 44.2% 51.0% 3.0% <2% 0.0% 13 37.4% 31.0% 13.9% <2% 13.0% 3.5% 13bis 43.1% 35.5% 16.0% <2% 0.0% 4.0% Table 3 Test No. Appearance RIGIDITY 1 Beautiful Appearance Rigid 1bis Beautiful Appearance Low stiffness 2 Beautiful Appearance Medium Stiffness 2bis Beautiful Appearance Low stiffness 3 Beautiful Appearance Very Rigid 3bis Beautiful Appearance Medium Stiffness 4 Beautiful Appearance Medium Stiffness 4bis Beautiful Appearance Low stiffness 5 Beautiful Appearance Low stiffness 5bis Beautiful Appearance Very low rigidity 6 Beautiful Appearance Rigid 6bis Beautiful Appearance Medium Stiffness 7 Appearance Correct Very rigid but brittle 7bis Appearance Correct Rigid but brittle 8 Incomplete Aspect Very rigid but brittle 8bis Incomplete Aspect Rigid but brittle 9 Beautiful Appearance Very Rigid 9bis Beautiful Appearance Rigid 10 Beautiful Appearance Rigid 10bis Beautiful Appearance Medium rigidity 11 Beautiful Appearance Very rigid 11bis Beautiful Appearance Rigid 12 Appearance Correct Very rigid but brittle 12bis Appearance Correct Rigid but brittle 13 Appearance Correct Very rigid but brittle 13bis Appearance Correct Rigid but brittle Table 4 Test No. Champagne capsule, aluminum, 70 microns thick (total thickness 130 microns) Champagne capsule, aluminum, 50 microns thick (total thickness 74 microns) PP derived from extrusion purges of recycled materials Reinforcing fiber A 25% 75% 0% B 23% 68% 10% C 50% 50% 0% D 45% 45% 10% E 25% 75% 0% F 23% 68% 10% G 50% 50% 0% H 45% 45% 10% Table 5 Test No. Aluminum part Part PE (PERD, PEBD, LIN....) Part PP Adhesives / Inks / Varnishes Fiber Miscellaneous Materials "Pollution" A 13.5% 11.5% 60.0% <1% 0.0% 15.0% B 12.1% 10.4% 54.0% <1% 10.0% 13.5% C 26.9% 23.0% 40.0% <1% 0.0% 10.0% D 24.2% 20.7% 36.0% <1% 10.0% 9.0% E 16.9% 8.0% 60.0% <1% 0.0% 15.0% F 15.2% 7.2% 54.0% <1% 10.0% 13.5% G 33.8% 16.0% 40.0% <1% 0.0% 10.0% H 30.4% 14.4% 36.0% <1% 10.0% 9.0% Table 6 Test No. Appearance RIGIDITY A Good appearance Rigid B Good appearance Very Rigid C Good appearance Rigid D Good appearance Very Rigid E Good appearance Rigid F Good appearance Very Rigid G Good appearance Rigid H Good appearance Very Rigid

[0061] The execution methods described are provided as illustrative examples and should not be considered exhaustive. Other execution methods may employ means equivalent to those described, for example. Execution methods may also be combined depending on the circumstances, or means used in one method may be used in another.

Claims

1. Method for recycling waste in the form of flakes containing plastics-based materials, characterized in that it comprises the following steps: - taking up the flakes; - compacting the flakes and feeding them into a plasticizing tool; - melting and mixing said flakes in the plasticizing tool; - injecting the extruded material under high pressure into a mould to form a part; - using the decomposition gases generated by the heating and pressurizing of the recycled material in the plasticizing tool to lubricate the material as it is injected into the mould and to compensate for the shrinkage of material during cooling, without supplying additional gas; - cooling the mould; - removing the part (10) from the mould.

2. Method according to Claim 1, characterized in that the flakes come from at least two sources of recycled materials.

3. Method according to Claim 2, characterized in that a first source generates decomposition gases at a temperature higher than 60°C.

4. Method according to Claim 2 or 3, characterized in that the first source substantially comprises plastic resin-based materials.

5. Method according to one of Claims 2 to 4, characterized in that the second source contains fillers such as aluminium fibres or particles, metals, fibres, inks, adhesives, varnishes, mineral fillers, oils, packaged product waste and washing waste.

6. Method according to one of Claims 2 to 5, characterized in that the second source comprises toothpaste tubes and / or champagne bottle caps and / or motor vehicle bumpers and / or dashboards.

7. Method according to one of Claims 2 to 6, characterized in that flakes from various sources are fed simultaneously to an inlet of the plasticizing tool.

8. Method according to one of Claims 2 to 6, characterized in that flakes from various sources are fed successively into the plasticizing tool.

9. Method according to one of Claims 2 to 7, characterized in that flakes from various sources are also fed successively into the plasticizing tool.

10. Method according to one of the preceding claims, characterized in that the apparent density of the flakes is between 0.1 and 2.

11. Method according to one of the preceding claims, characterized in that the molten material is injected into a mould at a flow rate of 0.1 m3 / h to 10 m3 / h.

12. Method according to one of the preceding claims, characterized in that the molten material is injected into a mould at a pressure of the order of 50 bar to 2000 bar.

13. Method according to one of the preceding claims, in which a partial degassing of the extruded material is carried out.

14. Method according to one of the preceding claims, in which a degassing of the part (10) is carried out after its removal from the mould.

15. Method according to one of the preceding claims, in which the part is a post or a pole or a profile or a stake or a board.