Systems and methods for producing food grade recovered polyolefins

Abstract

A process for producing a polyolefin food grade recycle comprising the steps of: collecting a post consumer plastic container bale (B); dividing the material provided by the bale into a first group (P1) of material for beverage purposes and a second group (P2) of material for non-beverage purposes; chopping the first set of materials to obtain plastic flakes; sorting the plastic sheets to obtain a first subset (S1) of PO sheets and a second subset (S2) of PET sheets; the first subset of flakes is processed by a polyolefin recirculator (6) to obtain the polyolefin food grade recycle.

Description

Technical Field

[0001] The present invention relates to a method for producing polyolefin food-grade recyclate and a system for processing post-consumer plastic waste to produce polyolefin food-grade recyclate. Background Art

[0002] Polyolefins belong to the thermoplastic material family and are widely used in the plastics industry due to their easy processing, low price, and good chemical and physical properties. There are four main types of polyolefins: LDPE (low-density polyethylene), LLDPE (linear low-density polyethylene), HDPE (high-density polyethylene), and PP (polypropylene); generally speaking, the most important polyolefins are polyethylene (PE) and polypropylene (PP). Polyolefins have a variety of applications and are widely used in the packaging industry. In particular, polyolefins are widely used in the food packaging industry: for example, plastic lids are typically made from polyethylene or polypropylene.

[0003] Due to their large-scale use in the packaging industry, polyolefins account for almost two-thirds of all post-consumer plastic waste, necessitating the establishment of an infrastructure suitable for the collection, sorting and recovery of polyolefins in post-consumer plastics.

[0004] Therefore, there is a need to recycle post-consumer polyolefins, so-called closed-loop recycling, whereby the recycled polyolefins are used for packaging (or other) purposes later in their life cycle.

[0005] Traditionally, in plastic waste processing plants, plastic bales from different sources and with different primary uses are collected and recycled. In these plants, post-consumer plastics typically undergo a recycling process to obtain plastic recyclates, which are then separated into different polymer groups; for example, at the end of the recycling process, PET-based and polyolefin-based recyclates are separated using different methods (e.g., using NIR and / or flotation techniques).

[0006] As mentioned above, one of the problems in the field of polyolefin recycling is that the polyolefins in plastic waste come from different sources and, depending on their primary use, can contain different amounts of contaminants; for example, polyethylene used for detergent bottles can absorb contaminants that may not be removed during the recycling process, making it unsuitable for use in many applications, such as the food industry.

[0007] Therefore, polyolefin recyclates obtained by known recycling processes may contain impurities and odors that preclude their further use in several applications, because in order to be suitable for reuse, polyolefin recyclates must meet predetermined quality requirements that cannot be achieved by recycling mixed plastic waste. For polyolefin recyclates to be considered at least potentially suitable for food contact, at least 95% of the starting material must originally be food-grade material. The term "polyolefin food-grade recyclate" as used above refers to material that has already been used for food contact or as food packaging and which can be shown to comply with current food safety standards for food contact as set out by agencies such as EFSA (European Food Safety Authority) and USFDA (United States Food and Drug Administration).

[0008] The recycling process includes multiple steps such as shredding plastic waste to obtain flakes, washing the flakes and squeezing out the washed flakes.

[0009] However, typical washing processes only remove contaminants from the polymer surface and fail to remove organic matter that has migrated into the polymer. Although remelting or re-extrusion of washed flakes can have a further cleaning effect, the purity levels achieved with those methods are generally insufficient for closed-loop recycling; therefore, polyolefin recyclate obtained with those methods may not be suitable for food contact.

[0010] Against this background, patent document EP3509811B1 describes a method for producing polyolefin recyclate, in particular HDPE recyclate. In particular, the document describes a method for purifying polyolefin recyclate to obtain polyolefin recyclate with an improved purity level compared to polyolefin recyclate available on the market to date.

[0011] However, prior art systems and methods for processing post-consumer plastic waste to obtain polyolefin food-grade recyclates have several drawbacks and could be improved. Indeed, there are several needs in the art.

[0012] In particular, there is a need for a post-consumer plastic waste processing system that can more efficiently produce polyolefin recyclate and can produce polyolefin food-grade recyclate suitable for food packaging. Another need in the art is to have a post-consumer plastic waste processing system for producing polyolefin food-grade recyclate in a particularly reliable manner that can provide information to the user about the properties of the recycled polyolefin and can meet the needs of the user.

[0013] Another need is to provide a post-consumer plastic waste processing system for producing polyolefin food-grade recyclate that minimizes energy costs and consumption. Summary of the Invention

[0014] The object of the present invention is to provide a system and method for producing polyolefin food grade recyclate to overcome the above-mentioned disadvantages of the prior art.

[0015] This object is fully achieved by the method and system of the present disclosure, as characterized by the appended claims.

[0016] According to one aspect of the present disclosure, there is provided a method for producing polyolefin food-grade recyclate (i.e., food-safe) suitable for direct contact with food. The method comprises the steps of collecting bales of post-consumer plastic containers.

[0017] The method comprises the steps of separating materials provided by the post-consumer plastic bales into a first group and a second group, wherein the first group of materials is formed of materials for beverage purposes and the second group of materials is formed of materials for non-beverage purposes.

[0018] The method comprises the step of shredding a first set of materials to obtain plastic flakes.

[0019] The method includes the steps of sorting the plastic flakes to obtain a first subset and a second subset. The first subset may be formed from PO (polyolefin) flakes. The second subset may be formed from PET (polyethylene terephthalate) flakes. The second subset may also be formed from other plastic materials. Thus, the second subset may include flakes that do not contain PO. It should be noted that during the sorting step, the plastic flakes may be divided into more than two subsets.

[0020] The method comprises the steps of processing the first subset of flakes through a polyolefin recycler.The first subset is processed through a polyolefin recycler to obtain polyolefin food grade recyclate.

[0021] Thus, according to one aspect of the present disclosure, post-consumer plastic material collected in the form of bales of post-consumer plastic containers is separated into material intended for beverage purposes and material intended for purposes other than beverages. The material intended for beverage purposes then undergoes a recycling process during which polyolefin flakes are separated from other plastic flakes and further recycled in a polyolefin recycler to obtain polyolefin food-grade recyclate. It should be noted that the PO flakes are derived from material previously used only for beverages; therefore, they do not contain contaminants that would make them unsuitable for direct contact with food and are of a sufficiently high food grade to be used in food packaging, for example, to produce plastic caps. This solution allows for the production of polyolefin recyclate that is both highly food-grade and more efficient. Furthermore, since the post-consumer material used to obtain the polyolefin recyclate has previously only been in contact with food, contaminants can be removed through a process that is simpler, less expensive, and requires less energy than prior art methods.

[0022] Therefore, the polyolefin recyclate obtained by this process is of very high quality.

[0023] In one embodiment, the step of processing the first subset of flakes through a polyolefin recycler includes the step of sorting the first subset of flakes. In one embodiment, the first subset of flakes is sorted based on polymer type and / or color. The first subset of flakes can also be sorted based on other criteria. Thus, different polyolefins, such as PP (polypropylene) and PE (polyethylene), can be sorted to tailor each type of polyolefin recyclate for a specific application. The flakes can also be sorted into different groups based on color so that the polyolefin recyclate obtained from each group is uniformly colored or similar in color.

[0024] The step of processing the first subset of flakes through a polyolefin recycler also includes a step of extruding the first subset of flakes. More specifically, the first subset of flakes is fed into one or more extruders; inside the extruders, the flakes are melted, then purified and re-pelletized. In particular, the extruders must be equipped with filters to remove undesirable components from the molten flakes. Thus, the molten flakes can be degassed and / or filtered and / or purified. Due to the high temperatures used, the extrusion step eliminates possible contamination due to volatile substances in the flakes.

[0025] The step of processing the first subset of flakes through a polyolefin recycler also includes the steps of post-extrusion cleaning and purification of the flakes.

[0026] The step of processing the first subset of flakes through a polyolefin recycler further comprises the step of pelletizing the extruded purified flakes to obtain polyolefin food grade pellets.

[0027] In an example, during the step of processing the first subset of flakes through a polyolefin recycler, additives are added to the extruded flakes in order to enhance the food grade of the obtained pellets.

[0028] In an example, the additives may include virgin polyolefins having a viscosity similar to or different from that of the recycled material, antioxidant additives, or other types of additives such as lubricants or coloring substances. In another example, the additives may include other materials that enhance the resulting food-grade particles.

[0029] In one example, a near infrared (NIR) spectroscopy system is used to classify the polymers. In another example, other techniques can be used to classify the polymers.

[0030] In an example, the method includes a preselection step. The preselection step is applied to the first subset of sheets. In an example, the preselection step is applied to the first subset of sheets before the step of processing the first subset of sheets. In other words, the preselection can be applied to the first subset of sheets before the sheets are conveyed to the polyolefin recycler. In another example, the first subset of sheets can be conveyed to the polyolefin recycler first and then the preselection step is performed. The preselection step includes inspecting the first subset to identify unwanted items and / or possible contaminants in the first subset of sheets. In an example, the preselection step is performed by an artificial intelligence visual control system and / or an olfactory sensor for identifying contaminants. In another example, the visual inspection can be performed by an operator. Thus, the preselection step can be automatic or manual. In an example, the preselection step is a batch process. Preselection ensures that unwanted or contaminated items do not enter the polyolefin recycler. In an example, the method includes a step of inspecting the food grade of the polyolefin recyclate after the processing step to verify that the food grade corresponds to a predetermined grade.

[0031] In an example, the method includes the step of collecting plastic caps for reusable or refillable beverage bottles. The method may also include the step of shredding the plastic caps to obtain plastic cap flakes. The plastic cap flakes are sorted into a first subset of flakes.

[0032] Processing the first subset of flakes through the polyolefin recycler also includes plastic lid flakes. Thus, in this example, the first subset of post-consumer material derived from post-consumer plastic container bales and the flakes derived from the plastic lids are processed to obtain polyolefin food-grade recyclate. It should be noted that both the plastic lid flakes and the first subset of post-consumer material derived from post-consumer plastic container bales are polyolefins that were previously used only for beverages and are therefore highly food-grade. The plastic lid flakes and the first subset of post-consumer material derived from post-consumer plastic container bales can be processed together or separately through the polyolefin recycler. It should be noted that the plastic lids are made of polyolefins.

[0033] In one example, the separation of materials into a first group and a second group is applied to the collected bales of post-consumer plastic containers, such that each collected bale of post-consumer plastic containers belongs to the first group or the second group. In this example, bales formed from post-consumer plastic containers used for beverage purposes are collected separately from bales formed from post-consumer plastic containers used for non-beverage purposes, so that each bale belongs to the first group or the second group. In another example, each bale of post-consumer plastic containers can include materials used for beverage purposes and materials used for non-beverage purposes; in this example, for each bale, the materials used for beverage purposes and the materials used for non-beverage purposes are separated into the first group and the second group, respectively.

[0034] In an example, the step of processing the first subset of flakes through a polyolefin recycler includes the step of further grinding the first subset of flakes to obtain homogenous flakes.

[0035] The step of processing the first subset of flakes through a polyolefin recycler may include the step of demetallizing the first subset of flakes.

[0036] The step of processing the first subset of flakes through a polyolefin recycler may include the step of washing the first subset of flakes.

[0037] The step of processing the first subset of flakes through a polyolefin recycler may include a deodorization step. Deodorization may be performed on the first subset of flakes after the shredding step, or on the polyolefin granules obtained after the pelletization step. It should be noted that deodorization is performed on unmelted (and therefore solid) flakes. During deodorization, the flakes are heated (e.g., to 60° C.). Some volatile compounds that may cause undesirable odors may be removed during a purification step performed on the flakes after extrusion; however, the purpose of purification is also to remove contaminants other than volatile compounds.

[0038] Therefore, in this disclosure, the term "deodorization" is used to refer to the process performed before extrusion, and the term "cleaning" is used to refer to the process performed after extrusion.

[0039] According to one aspect of the present disclosure, a system for processing post-consumer plastic waste to produce polyolefin food-grade recyclate suitable for direct contact with food is provided. The system for processing post-consumer plastic waste to produce polyolefin food-grade recyclate (hereinafter referred to as the "system") includes an input section. The input section receives bales of post-consumer plastic containers. The system includes a separation center. The separation center is configured to separate material provided by the bales of post-consumer plastic into a first group and a second group. The first group of materials comprises material for beverage purposes. The second group of materials comprises material for non-beverage purposes.

[0040] The system includes a shredder configured to shred a first set of materials to obtain plastic flakes.

[0041] The system includes a sorting unit configured to sort the plastic flakes into a first subset and a second subset. In an example, the first subset is formed of PO flakes. The second subset may be formed of PET flakes.

[0042] The system includes a polyolefin recycler configured to process a first subset of flakes to obtain polyolefin food-grade recyclate.

[0043] In an example, an input section of the system receives plastic caps used in reusable or refillable beverage bottles. The shredder can also be configured to shred the plastic caps to obtain plastic cap flakes. The plastic cap flakes are sorted into a first subset of flakes. The first subset of flakes processed by the polyolefin recycler also includes plastic cap flakes. The system can also include a preselection unit. In an example, the preselection unit is configured to receive the first subset of flakes upstream of the polyolefin recycler. The preselection unit is configured to inspect the first subset of flakes to identify undesirable items and / or possible contaminants in the first subset of flakes.

[0044] The system may include a final inspection unit configured to inspect the food grade of the polyolefin recyclate downstream of the polyolefin recycler to verify that the food grade corresponds to a predetermined grade.

[0045] The polyolefin recycler includes a polyolefin grinder. The polyolefin grinder of the polyolefin recycler is configured to further grind the first subset of flakes to obtain homogenous flakes.

[0046] The polyolefin recycler may include a demetallization unit configured to demetallize the first subset of flakes.

[0047] The polyolefin recycler includes a washing unit configured to wash the first subset of sheets.

[0048] The system may also include a screening unit to eliminate dust and plastic parts that are too small to be effectively separated; for example, the mesh size of the screen is less than 5 mm, or less than 3 mm or less than 2 mm.

[0049] The system may further comprise an elutriation unit, wherein bottle label residues and dust are removed by an air flow. Preferably, the screening unit and the elutriation unit are located upstream of the pre-selection unit. Alternatively, the screening unit and the elutriation unit may form part of the pre-selection unit.

[0050] The polyolefin recycler includes a sorting unit configured to sort the first subset of sheets. In an example, the sorting unit is configured to sort the first subset of sheets based on polymer type and / or color.

[0051] The polyolefin recycler includes an extruder configured to extrude a first subset of sheets.

[0052] The polyolefin recycler comprises a purification unit. The purification unit is configured to clean and purify the extruded flakes.

[0053] The polyolefin recycler comprises an enhancement unit. The enhancement unit is configured to add additives to the extruded flakes to enhance the food grade of the obtained pellets.

[0054] The polyolefin recycler includes a pelletizing unit. The pelletizing unit is configured to obtain food-grade polyolefin pellets from the extruded flakes. The polyolefin recycler may include a deodorizing unit. In one example, the deodorizing unit is located upstream of the extruder. The deodorizing unit is configured to deodorize the first subset of flakes. In another example, the deodorizing unit may be located downstream of the extruder. In this example, the deodorizing unit is located downstream of the pelletizing unit and is configured to deodorize the polyolefin pellets.

[0055] According to another aspect of the present disclosure, a method for producing polyolefin food-grade recyclate suitable for direct food contact may include the step of collecting post-consumer polyolefin-based food-grade plastic. The post-consumer polyolefin-based food-grade plastic is formed from material used for beverage purposes. In one example, the post-consumer polyolefin-based food-grade plastic may be provided from bales of post-consumer plastic containers. In one example, the bales of post-consumer plastic containers are divided into a first group and a second group, wherein the first material group is formed from material used for beverage purposes and the second material group is formed from material used for purposes other than beverage purposes. In one example, according to one or more aspects of the present disclosure, the post-consumer polyolefin-based food-grade plastic may be derived from the first group consisting of material used for beverage purposes. The method includes the step of shredding the post-consumer polyolefin-based food-grade plastic to obtain flakes. The method includes the step of processing the flakes through a polyolefin recycler to obtain polyolefin food-grade recyclate. The method includes the step of inspecting the post-consumer polyolefin-based food-grade plastic to obtain a physical property parameter. In one example, the physical property parameter represents a melt index of the post-consumer polyolefin-based food-grade plastic. The method includes the steps of separating post-consumer polyolefin-based food-grade plastics based on physical property parameters. Specifically, the post-consumer polyolefin-based food-grade plastics are separated into a plurality of groups. Furthermore, corresponding physical property parameters are assigned to each of the plurality of groups. The method includes the steps of providing a package. The method includes the steps of introducing a predetermined amount of polyolefin food-grade recyclate into the package. The predetermined amount of polyolefin food-grade recyclate placed in the package is homogeneous with respect to the physical property parameters. The method includes the steps of providing each package with information related to the physical property parameters of the polyolefin food-grade recyclate contained in the package.

[0056] Note that the polyolefin flakes are derived from materials previously used only for beverage purposes, so they are free of contaminants (excluding those that could come into direct contact with food) and are sufficiently food-grade to be used in food packaging, for example, to produce plastic caps. Thus, polyolefin recyclate can be obtained at a high food grade and more efficiently. Furthermore, given that the post-consumer material used to obtain the recycled polyolefins previously came into contact only with food, such contaminants can be removed through a simpler method with lower cost and energy consumption compared to prior art methods.

[0057] Therefore, the recycled polyolefin obtained by this process is of particularly high quality.

[0058] In addition, post-consumer plastics are inspected and sorted based on physical property parameters, and food-grade recycled polyolefins are packaged in packaging that provides information related to the physical property parameters of the recycled polyolefins. This solution allows users to obtain information about the properties of the recycled polyolefins within the packaging (e.g., the melt index of the recycled polyolefins), which is important for subsequent processes (e.g., injection molding or compression molding) that use the recycled polyolefins to produce final products. Thus, users can select recycled polyolefin packaging based on their needs.

[0059] Note that this aspect (collection of post-consumer polyolefin-based food-grade plastics, separation thereof according to physical property parameters, and provision of information related to the physical property parameters of polyolefin food-grade recyclate contained in packaging) can be combined with one or more of the other steps of the method according to the present disclosure; however, it is not inseparable from these steps. In addition, post-consumer polyolefin-based food-grade plastics formed from materials used for beverage purposes can be obtained according to one or more aspects of the present disclosure (e.g., separation from container bales as explained in the present disclosure) or from other sources and methods (e.g., collection of post-consumer plastic caps). Thus, according to one aspect of the present disclosure, a first subset provides food-grade polyolefin-based post-consumer plastic flakes formed from materials used for beverages.

[0060] In one embodiment, the physical property parameters are derived by examining the wafer.

[0061] In one example, the flakes are separated based on color. Additionally, the flakes can be sorted based on polymer type. Physical property parameters can be obtained based on scales.

[0062] In particular, melt index ranges can be associated with post-consumer plastics based on color, since typically in this field each color is associated with a specific melt index range. In one example, food-grade polyolefin-based post-consumer plastics are separated based on primary application prior to the shredding step, and physical property parameters are obtained based on the primary application. Note that in another example, the flakes can be divided based on the primary application. "Primary application" refers to the application of the post-consumer plastic during its consumption (e.g., plastic previously used as bottle caps in sparkling beverages, still beverages, or plastic used as milk bottles, etc.). Note that in the plastics industry, plastics with certain properties (particularly melt index) are used in each application; therefore, knowing the primary application of the post-consumer plastic providing the flakes, it is possible to assign a melt index range (and other properties) to that plastic.

[0063] It is conceivable that the inspection and classification of the sheets is based both on color and on primary use, or on one of the above criteria.

[0064] Specifically, the flakes are sorted based on the color and / or primary application of the plastic from which they are supplied. A range of polymer melt indices can be estimated, and the flakes are divided into different groups based on the estimated melt indices for each color and / or primary application. The flakes in each group are then assigned corresponding physical property parameters. This sorting is particularly simple, reliable, and cost-effective. The method can include the step of separating the flakes into a plurality of subsets based on the physical property parameters. Note that the physical property parameters can be obtained according to any of the aforementioned criteria. Within each subset, the flakes are homogeneous with respect to the physical property parameters. In other words, the flakes in each subset have a specific range of values ​​for the physical property parameter, which is the same for all flakes in that subset.

[0065] The method may include the step of individually processing each of the plurality of subsets through a polyolefin recycler to obtain a corresponding plurality of polyolefin food-grade recyclate subsets.

[0066] In one embodiment, physical property parameters are obtained by performing a melt index test on food grade recycled polyolefin and / or flakes. Note that this test is performed according to industry known standards.

[0067] It is envisaged that the physical property parameters are obtained based on examination of the flakes according to one or more of the methods described above, or by melt index testing of the flakes and / or polyolefin food grade recyclate, or based on only one of these methods.

[0068] In one embodiment, the information regarding the physical property parameters of the polyolefin food-grade recyclate contained in the packaging includes information on how the physical property parameters were obtained. For example, it is contemplated to provide information explaining the physical property parameters of the grouped polyolefin food-grade recyclate obtained based on color separation flakes.

[0069] In one embodiment, the information related to the physical property parameters of the polyolefin food-grade recycled material contained in the packaging includes operational information indicating operational information for applying the polyolefin food-grade recycled material in a molding process to obtain a final product derived from the polyolefin food-grade recycled material in each packaging. The operational information is defined based on the operating conditions of the molding process.

[0070] In one example, the operational information includes information regarding a recommended percentage of polyolefin food-grade recyclate to be used in combination with virgin polymer.

[0071] The method may comprise a flake extrusion step. The method may comprise a pelletizing step of the extruded flakes to obtain food grade polyolefin pellets. Thus, according to an embodiment, the recycled polyolefin is recycled polyolefin pellets.

[0072] According to one aspect of the present disclosure, a post-consumer plastic waste processing system for producing polyolefin food-grade recyclate suitable for direct food contact includes an input unit configured to receive post-consumer polyolefin-based food-grade plastic formed from material used for beverage applications. The system includes a shredder configured to shred the food-grade polyolefin-based post-consumer plastic into flakes. The system includes a polyolefin recycler configured to process the flakes into polyolefin food-grade recyclate.

[0073] The system includes an inspection center for inspecting post-consumer polyolefin-based food-grade plastics to obtain physical property parameters. The physical property parameters represent the melt index of the post-consumer polyolefin-based food-grade plastics. The system also includes a separation center. The separation center is configured to separate the post-consumer polyolefin-based food-grade plastics into a plurality of groups based on the physical property parameters, wherein a corresponding physical property parameter belongs to each of the plurality of groups. The system also includes a packaging unit for introducing a predetermined amount of polyolefin food-grade recyclate into a package. The plurality of polyolefin food-grade recyclates placed in the package are homogeneous in terms of the physical property parameters.

[0074] The system comprises a labelling unit to provide each package with information on physical property parameters of the polyolefin food grade recyclate contained in the package.

[0075] Note that this aspect can be combined with other feature(s) of the system according to the present disclosure; however, it is not inextricably linked to these features.

[0076] In one example, the inspection center is configured to inspect the wafer to obtain physical property parameters.

[0077] In an example, at least one of the following conditions holds true:

[0078] - separating the flakes based on color and obtaining physical property parameters based on the color of the flakes,

[0079] - Post-consumer polyolefin based food grade plastics are separated based on main applications before the shredding stage and physical property parameters are obtained based on main applications.

[0080] Therefore, the above conditions can be verified simultaneously or individually.

[0081] In one embodiment, the separation center is configured to separate the flakes into a plurality of subsets based on a physical property parameter. The physical property parameter of the flakes in each subset is homogeneous. The polyolefin recycler is configured to process each of the plurality of subsets separately to obtain a corresponding plurality of food-grade recycled polyolefin subsets. In one embodiment, the inspection center is configured to perform melt index testing on the food-grade recycled polyolefin and / or the flakes to obtain the physical property parameter.

[0082] In one example, the physical property parameter information related to the physical property parameter of the polyolefin food-grade recyclate contained in the packaging includes information on how to obtain the physical property parameter.

[0083] In one example, the physical performance parameter information related to the physical characteristic parameters of the polyolefin food-grade recycled material contained in the packaging includes operational information indicating the use of the polyolefin food-grade recycled material in a molding process to obtain a final product derived from the polyolefin food-grade recycled material in each packaging, based on the operating conditions of the molding process. The operational information includes information on a recommended percentage of the polyolefin food-grade recycled material to be used in combination with virgin polymer. In one example, the food-grade recycled polyolefin is in pellet form. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] These and other features will become more apparent from the following description of a preferred embodiment, which is illustrated by way of non-limiting example in the accompanying drawings, in which:

[0085] - Figure 1A and Figure 1B shows the production and separation stages of recycled polyolefins according to one or more aspects of the present specification;

[0086] - Figure 2A 、 Figure 2B and Figure 3 Represents a process for closed-loop recycling of post-consumer plastic waste through a post-consumer plastic waste processing system according to the present disclosure for producing polyolefin food-grade recyclate suitable for direct food contact;

[0087] - Figure 4A and Figure 4B A polyolefin recycler used in a post-consumer plastic waste treatment system is shown;

[0088] - Figure 5 A post-consumer plastic waste processing system for producing polyolefin food-grade recyclate is shown;

[0089] - Figure 6 The viscosity of HDPE after several process cycles is shown;

[0090] - Figure 7 and Figure 8The results of experiments performed on the lid are shown. DETAILED DESCRIPTION

[0091] With reference to the accompanying drawings, reference numeral 1 indicates a post-consumer plastic waste processing system for producing polyolefin food-grade recyclate. Polyolefin food-grade recyclate is suitable for direct contact with food. The post-consumer plastic waste processing system 1 for producing polyolefin food-grade recyclate suitable for direct contact with food (referred to as the "system") includes an input section I for receiving bales B of post-consumer plastic containers. The bales B of post-consumer plastic containers (referred to as "bales") include plastic containers and lids. Specifically, the bales may include plastics for beverage purposes (or generally food packaging) and plastics for other purposes. In the example, post-consumer plastics for beverage purposes are received in the input section I separately from plastics for non-beverage purposes; therefore, in the example, each bale B received in the input section I contains plastics for beverage purposes or plastics for non-beverage purposes. Plastics used for beverages can be collected in smart bins (i.e., reverse vending machines) that collect empty beverage bottles (or bottles typically used to hold food), or at points of sale, where consumers pay a small deposit that is returned to them when they bring back the empty container after using the contents. Plastics used for beverages can also be collected at other locations, as long as the plastic containers are used only for food. Post-consumer plastics used for other purposes can be collected with municipal waste. This plastic is mixed plastic, meaning it has been used for different purposes and has come into contact with different materials (food and non-food). Generally, bundles B are formed by a post-consumer material collection center (POC), where empty plastic containers CO are collected after being used by users U. In this example, the input section I of the system 1 also receives post-consumer plastic caps C. In this example, these plastic caps are used for refillable beverage bottles. These plastic caps can also include caps that are separated from the body of the plastic beverage bottle. After being used by users U, the plastic caps C are collected at the post-consumer material collection center (POC). These plastic caps are primarily made of polyolefins. Preferably, they are collected separately from bale B. As mentioned above, this bale contains post-consumer plastic material. This material is separated into a first group P1, consisting of material intended for beverage use, and a second group P2, consisting of material intended for non-beverage use. The first group P1 consists of post-consumer polyolefin-based food-grade plastics intended for beverage use. The post-consumer polyolefin-based food-grade plastics are collected in an input unit. If the first group contains non-polyolefin-based plastics, a separation step is performed to obtain only post-consumer polyolefin-based food-grade plastics intended for beverage use. This plastic is then shredded. The material separation into the first and second groups is performed at separation center 2 of system 1. When the system receives plastic caps C in addition to bale B, the material separation step is performed only for that bale, as the collected plastic caps are from beverage bottles and are made exclusively of material intended for beverage use. Therefore, the first group of materials includes both the plastic caps from bale B and the material intended for beverage use.The materials are separated into a first group P1 and a second group P2 for use in the collected bales B of post-consumer plastic containers, such that each collected bale B belongs to either the first group P1 or the second group P2. The first group P1 consists solely of materials used for beverages (or generally for packaging food) and is therefore less contaminated than the second group P2; therefore, the first group P1 is more suitable for polyolefin recycling. After leaving the separation center 2, the first group of materials enters a plastics recycler R. Specifically, within the plastics recycler R, the first group undergoes several processes. For example, the plastics recycler R includes a shredder 3 for shredding the first group of materials to produce plastic flakes. Specifically, the shredder 3 shreds post-consumer polyolefin-based food-grade plastic to produce flakes. The plastic flakes are washed in a washing stage. The washing stage reaches high temperatures to remove contaminants from the post-consumer plastic flakes. In this example, the second group of materials can be processed separately from the first group of materials P1 in a plastics recycler similar to that used for processing the first group of materials. In this example, the washed flakes of the second group of materials P2 are collected for use in applications that do not require food-grade polyolefins.

[0092] Upon leaving the plastic recycler R, the washed flakes of the first group P1 are conveyed to a sorting unit 4, wherein the plastic flakes are separated into a first subset S1 formed of polyolefin flakes and a second subset S2 formed of PET flakes. It should be noted that the second subset may comprise flakes of other plastic materials in addition to PET. Preferably, the step of sorting the plastic flakes to obtain a first subset of flakes and a second subset of flakes is performed by flotation separation and based on specific gravity. In this method, the washed plastic flakes of the first group P1 are separated by flotation in water (or other liquid); since PET (the second subset) is denser than water and the polyolefins (the first subset) are less dense than water, the second subset S2 sinks while the first subset floats. The flakes are then dried. The step of sorting the plastic flakes to obtain a first subset of flakes and a second subset of flakes can be performed by other methods.

[0093] The first subset of flakes is then processed through a polyolefin recycler 6 to obtain polyolefin food-grade recyclate. Specifically, the polyolefin recyclate obtained from the polyolefin recycler 6 is in the form of pellets. Furthermore, plastic caps are also shredded in the shredder 3 to obtain plastic cap flakes. The plastic cap flakes may be washed in a washing stage. The plastic cap flakes C may be processed separately from the first material P1 in a plastic recycler R or together with it. It should be noted that the plastic cap flakes are sorted into the first subset of flakes, and therefore the first subset of flakes processed through the polyolefin recycler 6 also includes plastic cap flakes.

[0094] In another example, the plastic caps C can be fed directly into the polyolefin recycler 6 without any further processing in the plastic recycler R before entering the polyolefin recycler 6. The system 1 includes a preselection unit 5, wherein a preselection step is applied to the first subset of sheets S1 before the first subset of sheets S1 is fed into the polyolefin recycler 6. During the preselection step, the first subset of sheets is inspected to identify unwanted items and / or possible contaminants in the first subset of sheets. The preselection step can include a visual inspection performed by an operator or by an artificial intelligence system. An olfactory sensor or gas chromatography is used to identify contamination or unpleasant odors. Other methods can be used in the preselection step. After inspection in the preselection unit 5, the first subset is fed into the inlet 601 of the polyolefin recycler 6. Thus, the first subset of sheets (including the plastic cap sheets and the sheets originating from the first group of materials P1) is fed into the polyolefin recycler 6. The polyolefin recycler 6 includes a polyolefin crusher 602. Specifically, the first subset of flakes may be further shredded in the polyolefin shredder 602 to obtain homogenous flakes.

[0095] The polyolefin recycler 6 comprises a demetallization unit 603, wherein the first subset of flakes is demetallized. Demetallizing the first subset of flakes is performed by magnetic means or by eddy currents.

[0096] The first subset of flakes is washed in a washing unit 604 of the polyolefin recycler 6. The washed first subset of flakes is sorted based on the flakes' polymer type and / or color. This sorting occurs in a sorting unit 605 of the polyolefin recycler 6 and can be performed using an NIR system, an optical system, flotation separation, or a centrifuge. The sorting unit 605 includes a polymer separator 605A, in which the flakes are sorted based on polymer type. The sorting unit 605 includes a color separator 605B, in which the flakes are sorted based on their color.

[0097] The classified flakes are then purified in the refining section 606 of the polyolefin recycler 6. The refining section includes an extruder 606A, where the first subset is extruded. The refining section includes a purification unit 606B, where the extruded flakes are filtered and purified to remove volatile substances and other contaminants.

[0098] The refining section 606 may further include an enhancement unit 606C. Specifically, in the enhancement unit, additives are added to the extruded flakes to enhance the food grade of the obtained particles. The additives include virgin polyolefins and / or antioxidants.

[0099] The polyolefin recycling 6 comprises a pelletizing unit 607, wherein the extruded flakes are converted into polyolefin food grade pellets in the pelletizing unit 607. The polyolefin recycler 6 may comprise a deodorizing unit D. The deodorizing unit D may be located before the refining section 606, and therefore before the extruder 606A. Thus, in an example, the first subset of flakes is deodorized before extrusion. In an example, the deodorizing unit is located after the washing unit. In other examples, the deodorizing unit may be located downstream of the inlet 601 of the polyolefin recycler, or downstream of the polyolefin pulverizer 602, or downstream of the demetallizing unit 603, or downstream of the classification unit 605. In another example, the deodorizing unit may be located upstream of the polyolefin recycler 6. In another example, the deodorizing unit D may be located downstream of the pelletizing unit 607 and deodorize the polyolefin pellets ( Figure 2B ).

[0100] System 1 includes a final inspection unit 7. Final inspection unit 7 receives polyolefin recyclate at outlet 608 of polyolefin recycler 6. Final inspection unit 7 inspects the polyolefin recyclate to verify that the food grade corresponds to a predetermined grade. Final inspection unit 7 is located at outlet O of the system. The pellets obtained at outlet O of the system are then conveyed to production unit M, where they are used to make new products, such as new containers and / or plastic caps, made from the pellets of polyolefin recyclate.

[0101] Typically, plastic covers are made of high-density polyethylene (HDPE).

[0102] HDPE can be processed multiple times without losing its essential properties and can therefore be recycled multiple times.

[0103] This has been confirmed experimentally.In this case, the applicant has carried out experiments on HDPE (virgin HDPE) in order to evaluate the properties of HDPE after one or more process cycles.

[0104] In these experiments, virgin HDPE was subjected to a recycling process comprising: extruding the virgin HDPE; compression molding the extruded HDPE to obtain plastic caps; shredding the plastic caps to obtain plastic flakes; and feeding the plastic cap flakes into an extruder. This cycle was repeated multiple times, ranging from 7 to 20 times. The extruder preferably used 100% flakes. However, other flake percentages (e.g., 50%) could also be used.

[0105] As can be noted in Figure 4, after several process cycles, the viscosity of the HDPE is actually similar to that of virgin HDPE. Specifically, the graph of Figure 4 shows the viscosity of virgin HDPE and HDPE after 2, 4, and 7 processing cycles as a function of shear rate.

[0106] It can be noticed that the lines of the different HDPE samples (virgin, processed 2, 4 and 7 times) almost overlap each other, indicating that the viscosity of the HDPE does not change after the above process cycles.

[0107] The dimensions of the caps, specifically the ovality and diameter of the caps made from virgin HDPE and processed HDPE (1-7 cycles) were also measured and the results (shown in Figure 5 The table ) shows that these parameters also remain almost the same during the entire HDPE processing.

[0108] Therefore, it can be concluded that HDPE can be processed multiple times without losing its main properties (viscosity and size, essential properties especially for the production of plastic caps).

[0109] In another experiment, HDPE flakes were obtained from post-consumer caps belonging to beverage bottles. The caps were collected in Italy and from mixed municipal waste. The caps belonged to beverage bottles (of all types). The caps were also collected from cap-only collection points.

[0110] The flakes are then sorted by color. 100% of the flakes are used in a molding process to obtain lids from the flakes.

[0111] The environmental stress cracking (ESC) of the lids in CO2 was then measured. To this end, the lids were placed on bottles filled with carbonated beverages and then the bottles were stored at 50°C. The results are shown in Figure 6 It can be noted that the cover made of white transparent sheet proved to be less durable over time than the red tinted sheet.

[0112] The white plastic flakes primarily come from water bottle caps. The reddish flakes primarily come from carbonated beverage bottle caps, which are made from a plastic with a high resistance to stress cracking.

[0113] In an example, the thickness of the cover wall, which is a measure of stress crack resistance, is increased by about 10-20%. In particular, the thickness of the lower wall (bottom) is increased.

[0114] Thus, the experiments show that post-consumer plastics retain their original properties to a large extent and that in this case the red hue lids offer the most promising post-consumer plastic for the production of beverage lids, in particular for carbonated beverages.

[0115] It was concluded that HDPE (both virgin and post-consumer) has the potential to be used and recycled multiple times in recycling processes.

[0116] However, there are factors that can have a significant negative impact on the recycling of HDPE.

[0117] For example, the presence of impurities such as paper and fibers can lead to undesirable odors in HDPE recyclate.

[0118] Impurities can also induce stress cracking in caps made from post-consumer HDPE. In addition, the type of virgin HDPE used to make the caps and the additives used in the cap production process can affect the quality of caps subsequently made from post-consumer HDPE.

[0119] According to one aspect of the present disclosure, post-consumer polyolefin-based food-grade plastic is inspected in an inspection center (IP) to obtain a physical property parameter representing the melt index of the post-consumer polyolefin-based food-grade plastic. Preferably, the physical property parameter includes a range of melt index values ​​or an exact value of the melt index of the post-consumer polyolefin-based food-grade plastic.

[0120] The melt index of a polymer is an index of the ease with which a molten polymer flows; it is measured by loading the molten polymer into a heated cylinder fixed with a small cylinder (diameter 2.095 mm and length 8 mm) at a certain temperature, applying a constant force to allow the polymer to flow through a capillary; the mass of polymer released in grams within 10 minutes corresponds to the value of the melt flow index.

[0121] The greater the mass of the leaked material, the greater the melt flow index and the lower the viscosity of the polymer.

[0122] Additionally, different sets of melt index ranges can be provided based on the degree of stress cracking, as the degree of stress cracking of a polymer is correlated to the value of the melt index.

[0123] Stress cracking of thermoplastic polymers is defined as "external or internal cracks in a plastic caused by tensile stresses below its short-term mechanical strength."

[0124] For example, melt index values ​​can be divided as follows:

[0125] Type 1

[0126] Melt index (2.16kg 90℃): 0.4-0.85g / 10min

[0127] Density: 0.95-0.965g / cm 3

[0128] Type 2

[0129] Melt index (2.16kg 90℃): 1.4-3.3g / 10min

[0130] Density: 0.95-0.962g / cm 3

[0131] Type 3

[0132] Melt index (2.16kg 90℃): 3.3-8.5g / 10min

[0133] Density: 0.95-0.962g / cm 3

[0134] For the melt index value, the degree of stress cracking can be estimated at each of the above groups. After obtaining the physical property parameters, the post-consumer polyolefin-based food-grade plastic is separated into a plurality of groups in a separation center SP according to the physical property parameters, wherein the corresponding physical property parameters belong to each of the plurality of groups. Therefore, each group has a relative melt index range or the same melt index value, and the physical property parameters of each group are different from the physical property parameters of another group. The post-consumer polyolefin-based food-grade plastic is shredded and then processed in a polyolefin recycler 6. Inspection can be performed after shredding, i.e., for flake inspection, or after the flakes are processed into recycled polyolefin (preferably pellets), or before shredding.

[0135] It is also possible to carry out more than one inspection stage before or after shredding, and before or after flake processing.

[0136] In one embodiment, the physical property parameters are obtained by inspecting the flakes. In one embodiment, the flakes are separated based on color, and the physical property parameters are obtained based on the color of the flakes.

[0137] In the plastics industry, colors are often associated with specific applications. For example, red is used to make plastics for sparkling beverage caps. This application requires high stress cracking values ​​and a specific melt index range. In another example, white plastic (HDPE) is used in milk bottles. Therefore, it is possible to associate an estimated melt index (range) with post-consumer plastics classified based on color.

[0138] In another example, prior to the shredding step, post-consumer polyolefin-based food grade plastics are separated based on primary application and physical property parameters are obtained based on the primary application. In other words, when the primary use of the post-consumer plastic is known, a range of melt index values ​​for the plastic can be estimated because it is known that each use requires a specific melt index value. Thus, the flakes (or plastic before shredding) are separated into different groups based on the color and / or color and / or type of polymer, and a melt index value (or range of values) is associated with each group, such as medium, high and low. Additionally, a stress cracking value can be associated with any group, for example, a group of white plastics previously used as milk bottles can have a melt index range of 0.4-0.85 g / 10 minutes, as well as high stress cracking resistance. Thus, sorting of post-consumer polyolefin-based food grade plastics made from used materials can be based on the color and / or origin of the plastic.

[0139] In another example, the melt index value of the plastic can be measured before or after shredding, or before or after processing in the recycler 6, by testing according to ISO Standard 1133-1.

[0140] Furthermore, after inspection, the flakes are separated into a plurality of subsets in a separation center SP based on the physical property parameters, wherein the flakes in each subset are homogeneous with respect to the physical property parameters. Thus, the flakes of one subset have the same melt index range, which is different from the flakes of another subset.

[0141] Furthermore, in such examples, each of the plurality of subsets is separately processed through the polyolefin recycler 6 to obtain a corresponding plurality of food-grade recycled polyolefin subsets.

[0142] It is conceivable that caps and bottles having identical physical property parameters can be separated and processed together.

[0143] Additionally, food grade recycled polyolefins may be sent to a final inspection unit 7 .

[0144] Figure 1A and Figure 1B Two different embodiments are shown, in which inspection and separation take place on particles and flakes, respectively.

[0145] Additionally, the flakes are extruded and pelletized to form food grade polyolefin pellets.

[0146] A predetermined amount of food-grade polyolefin pellets is introduced into packages in the packaging unit PA. The food-grade recycled polyolefin of the predetermined amount of food-grade recycled polyolefin placed in the packages is homogeneous in terms of physical property parameters. Thus, each package contains pellets of the same melt index range.

[0147] Furthermore, in the labelling unit LA, each package is provided with information about the physical property parameters of the food grade recycled polyolefin contained in the package.

[0148] This information can be provided in the form of a label or QR code on the packaging.

[0149] Information related to the physical property parameters of the food-grade recycled polyolefin contained in the packaging may include information on how the physical property parameters were obtained. For example, the information related to the physical property parameters of the recycled polyolefin may indicate whether the physical property parameters were inspected based on color, plastic origin, melt index testing, or whether the cap and bottle were separated and processed separately. The information related to the physical property parameters of the recycled polyolefin may also indicate the exact range or value of the melt index of the pellets within the bag, as well as an estimate of the resistance to stress cracking. Furthermore, the information related to the physical property parameters of the food-grade recycled polyolefin contained in the packaging may include operational information indicating the use of the food-grade recycled polyolefin in the molding process and the final product derived from the food-grade recycled polyolefin in each package, based on the operating conditions of the molding process. For example, such information may indicate a recommended percentage of food-grade recycled polyolefin to be used in combination with virgin polymer. Furthermore, the information may indicate a recommended percentage of food-grade recycled polyolefin to be used in combination with virgin polymer in the package for a specific process with specific operating conditions.

[0150] Based on the melt index range associated with the package, the package can contain information (a recipe) on the recommended percentage of recycled polyolefin to be combined with virgin polymer in the injection or compression molding process for producing a plastic lid of a specific thickness and for sparkling beverages. Some examples of such recipes are shown below, with recommended and optimal values ​​for pellets (of recycled HDPE) that meet the index range for each melt index interval, depending on the desired thickness of the lid and the type of beverage. MI stands for melt index.

[0151]

Claims

1. A method for producing polyolefin food-grade recyclate suitable for direct food contact, the method comprising the following steps: - Collection of bales of post-consumer plastic containers (B); - separating the material provided by the bundle of post-consumer plastic containers (B) into a first group (P1) formed of material intended for beverage purposes and a second group (P2) formed of material intended for non-beverage purposes; - shredding the material of said first group (P1) to obtain plastic flakes; - sorting the plastic flakes to obtain a first subset (S1) formed of PO flakes and a second subset (S2) formed of PET flakes; - Processing the first subset of flakes (S1) through a polyolefin recycler (6) to obtain said polyolefin food grade recyclate.

2. The method according to claim 1, wherein The step of processing the first subset of flakes (S1) through the polyolefin recycler (6) comprises the step of sorting the first subset of flakes (S1) based on polymer type and / or color.

3. The method according to claim 2, wherein: The step of processing the first subset of sheets (S1) through the polyolefin recycler (6) further comprises the following steps: - extruding said first subset of sheets (S1); - Cleansing and purification of extruded flakes; - The extruded flakes are pelletized to obtain polyolefin food grade pellets.

4. The method according to claim 3, wherein: Additives are added to the extruded flakes to enhance the food grade of the resulting particles, including virgin polyolefins and / or antioxidants.

5. The method according to claim 3 or 4, wherein: The step of processing the first subset of flakes (S1) through a polyolefin recycler (6) further comprises a deodorization step, wherein the first subset of flakes is deodorized after the extrusion step or the polyolefin food grade pellets obtained from the step of pelletizing the flakes are deodorized.

6. The method according to any one of claims 2 to 5, wherein The polymer separation was performed by means of an NIR system.

7. The method according to any of the preceding claims, further comprising a preselection step applied to the first subset of sheets (S1) before the step of processing the first subset of sheets in the polyolefin recycler (6), the preselection step comprising inspecting the first subset (S1) to identify undesirable items and / or possible contaminants in the first subset of sheets.

8. The method according to claim 7, wherein: The preselection step is performed by an artificial intelligence vision control system and / or an olfactory sensor for detecting contamination.

9. The method according to any one of the preceding claims, further comprising the step of checking the food grade of the polyolefin recyclate downstream of the processing step to verify that the food grade corresponds to a predetermined grade.

10. The method according to any one of the preceding claims, comprising the steps of: - Collect plastic caps used in refillable / reusable beverage bottles (C); - shredding the plastic lids to obtain plastic lid flakes, wherein the plastic lid flakes are sorted into the first subset of flakes (S1), Wherein, the first subset of sheets processed through the polyolefin recycler (6) also includes the plastic cover sheets.

11. A method according to any one of the preceding claims, wherein The separation of materials into a first group (P1) and a second group (P2) is applied to the collected bales (B) of post-consumer plastic containers such that each collected bale of post-consumer plastic containers belongs to the first group or the second group.

12. A method according to any one of the preceding claims, wherein The step of processing the first subset of sheets through the polyolefin recycler (6) comprises the following steps: - further grinding said first subset of flakes (S1) to obtain homogeneous flakes; - demetallizing said first subset of flakes (S1); - washing the first subset of sheets (S1); - sorting said first subset of flakes based on polymer type and / or color; - extruding said first subset of sheets (S1); - Cleansing and purification of extruded flakes; - Adding additives to the extruded flakes to improve the food quality of the obtained granules; - Pelletizing the extruded flakes to obtain polyolefin food grade pellets.

13. A method according to any one of the preceding claims, wherein The step of sorting the plastic flakes is performed by flotation separation and based on specific gravity to obtain a first subset of flakes and a second subset of flakes.

14. A post-consumer plastic waste processing system (1) for producing polyolefin food-grade recyclate suitable for direct contact with food, the post-consumer plastic waste processing system (1) comprising: - an input section (I) for receiving bales (B) of post-consumer plastic containers; a separation centre (2) for separating the material provided by the bales of post-consumer plastic containers into a first group (P1) formed of material intended for beverage purposes and a second group (P2) formed of material intended for non-beverage purposes; - a shredder (3) configured to shred the first set of materials to obtain plastic flakes; a sorting unit (4) configured for sorting the plastic flakes to obtain a first subset (S1) formed of PO flakes and a second subset (S2) formed of PET flakes; - a polyolefin recycler (6) configured for processing the first subset of flakes (S1) to obtain said polyolefin food grade recyclate.

15. The post-consumer plastic waste treatment system (1) according to claim 14, wherein The input section (I) receives plastic caps (C) used in refillable / reusable beverage bottles, and wherein the shredder (3) is further configured to shred the plastic caps to obtain plastic cap flakes, which are sorted into the first subset of flakes (S1), wherein the first subset of flakes processed by the polyolefin recycler also includes the plastic cap flakes.

16. The post-consumer plastic waste treatment system (1) according to any one of the preceding claims 14-15, further comprising a pre-selection unit (5), which is configured to receive the first subset of sheets upstream of the polyolefin recycler (6) and to inspect the first subset of sheets (S1) to identify undesirable items and / or possible contaminants in the first subset of sheets.

17. The post-consumer plastic waste treatment system (1) according to any one of the preceding claims 15-16, comprising a final inspection unit (7) configured to inspect the food grade of the polyolefin recyclate downstream of the polyolefin recycler (6) to verify that the food grade corresponds to a predetermined grade.

18. Post-consumer plastic waste treatment system (1) according to any one of the preceding claims 14-17, wherein The polyolefin recycler (6) comprises: a polyolefin grinder (602) configured to further grind said first subset of flakes (S1) to obtain homogeneous flakes; - a demetallization unit (603) configured for demetallizing said first subset of sheets (S1); a washing unit (604) configured to wash the first subset of sheets; - a sorting unit (605) configured to sort the first subset of sheets based on polymer type and / or color; - an extruder (606A) for extruding said first subset of sheets; - a purification unit (606B) configured for cleaning and purifying the extruded flakes; - an enhancement unit (606C) for adding additives to the extruded flakes to improve the food grade of the obtained granules; - a granulation unit (607) configured to obtain polyolefin food grade granules from said extruded flakes; - a deodorizing unit (D) for deodorizing said first subset of flakes or polyolefin particles.

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