WO2025099325A1

WO2025099325A1 - Process for treating an input waste material having an initial content of intrinsic impurities

Info

Publication number: WO2025099325A1
Application number: PCT/EP2024/081912
Authority: WO
Inventors: Dennis Max MEISEL; Jürgen Deinert; Marcus SCHULZE
Original assignee: saperatec GmbH
Current assignee: saperatec GmbH
Priority date: 2023-11-10
Filing date: 2024-11-11
Publication date: 2025-05-15
Anticipated expiration: 2026-05-10
Also published as: LU505478B1

Abstract

A process for treating an input waste material is disclosed. The input waste material comprises at least one polymer fraction, the input waste material having an initial content of intrinsic impurities located in the at least one polymer fraction. The process comprises acid washing the input waste material with an acidic solution, followed by removing the acidic solution comprising at least part of intrinsic impurities, thereby obtaining an acid washed output waste material. The process further comprises mixing a non-solvent in a liquid state with the acid washed output waste material in an apparatus for forming an azeotrope mixture of the non-solvent with intrinsic impurities, followed by outputting at least part of intrinsic impurities in a gaseous state from the apparatus, thereby obtaining an acid washed mixed output waste material.

Description

Title: _ Process for treating an input waste material having an initial content of intrinsic impurities

Field of the Invention

[0001] The invention comprises a process for treating an input waste material having an initial content of intrinsic impurities. The invention further comprises an output waste material.

of the Invention

[0002] The subsequent use of polymer recyclates, i.e., recycled polymers, is dependent on their purity level. Impurities like volatile organic compounds (VOC), even in a low content, for example, in the ppm-range, can prevent the suitability of the polymer recyclates in their implementation in specific product categories, particularly in packaging applications, more particularly in cosmetic packaging applications and even more particularly in food packaging applications.

[0003] European Packaging and Packaging Waste Directive (PPWD - Directive 94/62ZEC) defines measures to prevent the production of packaging waste and measures to promote reuse of packaging and recycling and other forms of recovering packaging waste in https://www.europarl.europa.eu/RegData/etudes/BRIE/2023/745707/EPRS_BRI(2023)745 707_EN.pdf, Guillaume Ragonnaud, PE 745.707, March 2023, assessed on 26. October 2023. The European Directive 94/62ZEC states, for example, that a mandatory content of the polymer recyclates in new plastic products should be 30% in 2030.

[0004] The packaging materials in the food applications are highly regulated because the packaging materials are in contact with food intended for humans and/or animals. Thus, these packaging materials must be very pure. The European Directive 94/62ZEC also states high purity levels that the packaging materials must achieve and limits of residual content these packaging materials can have. Problems are currently arising for fulfilling the requirements of the European Directive 94/62ZEC to provide enough polymer recyclates in the new plastic products while fulfilling the high purity level required in the food packaging applications.

[0005] The European Directive 94/62ZEC further sets out other requirements that the packaging materials placed on the EU market must meet. The presence and content of substances of concern, termed impurities, in the polymer recyclates have to be minimized.

[0006] The polymer recyclates, i.e., the recycled polymers, comprise for example one polymer fraction comprising a polymer matrix. In another example, the polymer recyclates, i.e., the recycled polymers, comprise two or three polymer fractions, as in used beverage cartons (UBC). The UBC comprises, in particular, alternating fractions of polyethylene (PE), paper, PE, aluminium and PE.

[0007] The polymer recyclates originates, in a first example, from industrial activities. These polymer recyclates are termed post-industrial plastic waste. The polymer recyclates originates, in a second example, from household rubbish. These polymer recyclates are termed post-consumer plastic waste. A. Cabanes, F.J. Valdes and A. Fullana, A review on VOCs from recycled plastics, Sustainable Materials and Technologies (2019), https://doi.org/10.1016/ j.susmat.2020.e00179 discloses these definitions of the postindustrial plastic waste and the post-consumer plastic waste.

[0008] Major drivers in the past were the recycling of the post-industrial waste termed postindustrial in-house scrap recycling, and the recycling of post-consumer polyethylene terephthalate (PET) waste termed post-consumer PET recycling. A post-consumer plastic waste of PET was a main focus in recycling processes because beverage bottles made of PET have a collection system in some countries, for instance, reverse vending machines for empty bottles made of PET in Germany and are substantially clean or are easy to clean.

[0009] A post-consumer PET recycling process comprising basic washing at high temperatures was already focused on in the past. The basic washing comprised basic washing an input waste material made of PET with an optional solution made of one or more detergents as disclosed in the international patent application WO 1997020645 Al.

[0010] A post-consumer polyolefin waste recycling became in the past 10 years more and more in the focus. The post-consumer polyolefin waste recycling process, in particular, the post-consumer PE recycling process comprised basic washing at high temperatures. The basic washing in WO 2023180529A1 comprised basic washing an input waste material comprising a polyolefin fraction with a solution of sodium hydroxide (NaOH) at a content from 0.1 to 5.0 wt%, more preferably from 0.2 to 3.5 wt%, still more preferably from 0.3 to 2.5 wt%, based on the total weight of the washing liquid and at temperatures of 60°C. In WO 2023180529 Al, it is intended to use a solution of sodium hydroxide (NaOH) with a substantially low content of NaOH.

[0011] The post-consumer PE recycling process has been inspired by the post-consumer PET recycling process, especially the step of the caustic, i.e., basic washing, commonly and classically used in the post-consumer PET recycling process. The step of the caustic, i.e., basic washing, was economically and environmentally advantageous in the post-consumer PET recycling process, thus this step of caustic, i.e., basic washing was applied identically in the post-consumer PE recycling process. There was no need and no interest into changing the experimental conditions step of the caustic, i.e., basic washing, and even less changing the content of the basic solution.

[0012] The polymer recyclates comprise impurities, especially in the case of the packaging waste.

[0013] A first type of impurities, i.e., Type-I impurities, concerns impurities comprised in an input waste material, i.e., extrinsic impurities, for example, in a packaging material. This first type of impurities originates from a collecting and sorting routine of waste, such as stones, wood, foreign polymers, comprised in the input waste material. This first type of impurities originates also or alternatively from components of multilayer systems, i.e., multiple layer structure of the input waste material, such as remaining fibres of paper-based packaging in used beverage cartons (UBC), or aluminum from aluminium barrier laminates (ABL).

[0014] These extrinsic impurities are located on a surface of the polymer matrix. The extrinsic impurities might be, for example, ink particles, pigments particles, or varnish particles. Ink particles are, for example, superficially applied colored substances on the polymer matrix and are used to build up layers in the input waste material.

[0015] Ink particles, pigments particles, or varnish particles can also be very difficult to remove by pure mechanical forces because the ink particles, pigments particles, or varnish particles can also migrate beneath the surface of the polymer layer and thus, hereby become intrinsic impurities. In addition, certain polymer or recycling process steps can lead to the integration of the prior extrinsic ink particles, pigment particles, or varnish particles into the polymer matrix, like agglomeration or shredding, and thus the ink particles, pigment particles, or varnish particles become intrinsic impurities as well. Polymer or recycling process steps generating temperatures >100 °C (sometimes only briefly) can cause the merge of ink particles, pigment particles, or varnish particles into the polymer matrix because at these temperatures polymers like LDPE start to melt and to agglomerate.

[0016] CA 3 152656 Al aims at providing solvents that can be reversibly converted between hydrophobic and hydrophilic forms. CA 3 152 656 Al discloses anionic switchable hydrophilicity solvents (ASHS). These solvents can be reversibly converted between hydrophobic and hydrophilic forms. The ASHS comprise a carboxylic acid, a water-soluble base, and water. The carboxylic acid comprises one or more compounds of the formula RCO2H, wherein R is a substituted or unsubstituted C6 to Cl l alkyl group that is linear, branched, or cyclic, a substituted or unsubstituted C6 to Cl l alkenyl group that is linear, branched, or cyclic, or a substituted or unsubstituted C6 to Cl 1 polyunsaturated group that is linear, branched, or cyclic. The carboxylic acid as a polar substance is not capable of dissolving hydrophobic oils. CA 3 152 656 Al discloses that the ASHS can be reversibly converted between hydrophobic and hydrophilic forms. The addition and the removal of an acidic gas, namely CO2, further effects the conversion between the hydrophobic and hydrophilic forms of the ASHS. The ASHS is used in a washing process for oil -contaminated bottle pieces made of high-density polyethylene (HDPE). The oil contamination is hereby a surface contamination of polymer matrixes. The oils are thus extrinsic impurities and not intrinsic impurities. The HDPE bottle pieces contaminated by the oil can be cut into small pieces and mixed with the carboxylic acid (RCO2H) of the ASHS. The ASHS removes the oil from the pieces, which can be removed by filtration. A basic aqueous solution can be added to the oil and RCO2H mixture, washing the carboxylic acid from the oil. The oil can be decanted, and the aqueous solution treated with CO2.

[0017] A second type of impurities, Type-II impurities, concerns intrinsic impurities, i.e., intrinsic contaminants, also known as inborn impurities.

[0018] These intrinsic impurities are embedded in the polymer matrix. Therefore, these impurities cannot be removed by simple mechanical recycling processes.

[0019] The extrinsic impurities, i.e., Type-I impurities, and the intrinsic impurities, i.e., Type-II impurities, can be classified in non-intentionally added substances (NIAS), and in intentionally added substances (IAS). [0020] The NIAS are known as chemicals that have not been added for a technical reason into an article, such as into food contact articles. NIAS have various sources and can be grouped into side products, breakdown products, and contaminants. Side products are often formed during a production of articles starting from input substances and onto which further manufacturing stages are applied on. Structure-providing constituents of food contact materials, e.g., polymers, fibers, as well as additives, e.g., antioxidants, UV-stabilizers, are often degraded during their manufacture and use, thus leading to various breakdown products. The breakdown products from recycling of LDPE are oxidized degradation products like hexadecanoic acid. Contaminants may have very different sources. Starting substances used in the production of food contact materials often contain impurities or environmental contaminants which may remain in the final food contact article. Processing and especially recycling can also introduce many different contaminants in the food contact articles. Typical recycling-related NIAS are mineral oil hydrocarbons (MOHs), bisphenols, phthalates, and photo initiators found in recycled paper and board as well as flavor compounds, oligomers, and additives found in recycled plastics.

[0021] The IAS are added during the manufacturing process of materials to achieve a technical effect in these materials, such as the addition of antioxidants, like phenols, or phosphates, UV-stabilizers, or slipping agents, like stearate salts. These IAS can be beneficial for a first application, i.e., use, of the materials, but after recycling these materials, the obtained recycled materials are used for a second application and very often for other applications. The IAS for the first application can, under some circumstances, be seen as impurities for the second application. This is often the case if the second application is in the area of contact-sensitive or food applications.

[0022] In a first example, the Type-II impurities, i.e., intrinsic impurities, are volatile organic compounds (VOCs). The VOCs might be embedded into the polymer matrix. The VOCs are defined, for example, in A. Cabanes, F.J. Valdes and A. Fullana, A review on VOCs from recycled plastics, Sustainable Materials and Technologies (2019), https://doi.org/10.1016/ j.susmat.2020.e00179. VOCs can originate from the polymer fraction due to degradation during the polymer life cycle, e.g. monomer formation, or oligomer formation. VOCs can diffuse into the polymer fraction during the use of the packaging material, like in the case where food ingredients diffuse into packaging materials. VOCs are in most cases NIAS. Indeed, due to the fact that polymer manufacturing requires temperatures >100 °C, VOCs should not be present in the manufactured polymer, and so if VOCs are present in the resulting manufactured polymer, there are NIAS. VOCs can also be considered in rare cases as IAS.

[0023] The VOCs have a strong diffusion and migration tendency in polymers due to their substantially small molecular weight and thus are highly integrated within the polymer matrix of the polymers. In other words, the VOCs cannot be substantially removed from a packaging material by applying outer mechanical forces or surface washing processes.

[0024] The VOCs might also be located on the surface of the polymer matrix, and so be considered, i.e., classified, as extrinsic impurities.

[0025] The VOCs might be NIAS, whether extrinsic impurities or intrinsic impurities.

[0026] In a second example, the Type-II impurities, i.e., intrinsic impurities, are inorganic contaminants. The inorganic contaminants are, for example, titanium dioxide as white pigment, or calcium stearate as slipping agent. These substances are IAS, but a chemical change during processing, life-time, or recycling into NIAS can happen. These type of intrinsic impurities mainly differ from VOCs due to their chemical nature. Normally, inorganic contaminants do not have a boiling point, thus these inorganic contaminants cannot be removed from the waste material by changing their state from a liquid state to a gaseous state, for example. Some inorganic contaminants have an ionic chemical nature that do not allow them to migrate into the polymer fraction and/or in the waste material.

[0027] In a third example, the intrinsic impurities might also be ink particles, pigments particles, or ink and/or pigment processing aids. The ink particles are, for example, masterbatch inks, also known as dyes. These dyes are embedded in the polymer matrix (for instance made of LDPE), thus obtaining colored plastics or films.

[0028] A third type of intrinsic impurities, i.e., Type-III impurities, are metal, and metal ions comprised in the polymer fraction, such as lead, mercury, cadmium, hexavalent chromium. The content of these metals and metal ions is intended to be reduced by the Restriction of Hazardous Substances Directive 2002/95/EC (RoHS 1), short for “Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment”. Therefore, there is a need for providing an output waste material that is compliant with RoHS 1. [0029] A summary of examples of the types of Type-I impurities, i.e., extrinsic impurities and Type-II impurities, i.e., intrinsic impurities, in polymer recyclates are developed in the following Table 1.

Table 1:

[0030] * Even if no specific migration limit (SML) is required, the overall migration limit (OML) for the sample has to be respected. OML: 60 mg kg ¹ of the food or 10 mg dm ² of the material.

[0031] EP 4 163 325 Al aims at providing a method when using a combination of coloring agents. The coloring agents comprise an organic molecule with a low molecular weight and are in a colored plastic article having an outermost layer comprising a crosslinked silicon compound. EP 4 163 325 Al discloses a method for decoloring this colored plastic article, wherein the colored plastic article comprises at least two layers. A first layer of the at least two layers is an outermost layer and forms a surface of the plastic article. A second layer of the at least two layers is a color layer and comprises a plastic material and a coloring agent. The plastic material includes polar polymers. The decoloring process involves shredding the colored plastic articles into granulate or powder, then treating the articles in a decoloring bath. The decoloring bath is an acidic or basic aqueous decoloring bath. The decoloring bath comprises water, polar and/or non-polar solvents, and either an oxidizing or reducing agent, with the pH adjusted by acid or base. The oxidizing/reduction agent is used to penetrate the plastic article and transforms the insoluble pigment into a soluble form.

[0032] EP 3 950799 Al discloses a method for solvent-based recycling of plastic waste film material. The method involves moving a plastic film material across at least one solvent bath containing a solvent that dissolves the first polymer component while leaving the second polymer component intact. The treated materials primarily include various types of plastic films, especially multilayer films, where at least one layer comprises a polymer that can be selectively dissolved in the solvent. The solvent include a range of organic and inorganic chemicals, tailored to dissolve specific polymers without degrading others, thereby facilitating the separation of polymer components. The solvent of the least one bath is, for example, selected from the group comprising ketones, esters, organic acids, water and/or mixtures thereof. The method enables to increase the purity of recycled polymers and reduces environmental impact by enabling the reuse of polymers from complex plastic wastes that include multiple polymer types. The method of EP 3 950 799 Al enables to eliminate impurities which are caged between the polymer chains. This effect is only possible in the case where the plastic film material is dissolved.

[0033] As already mentioned above, simple mechanical recycling processes cannot currently remove intrinsic impurities.

[0034] Therefore, there is a need for a process capable of treating an input waste material comprising at least one polymer fraction, the input waste material having an initial content of intrinsic impurities, preferably for removing intrinsic impurities from the input waste material to obtain a purer output waste material, i.e., to obtain an output waste material with a reduced content of intrinsic impurities relative to the initial content of intrinsic impurities. [0035] There is further a need for a process capable of removing intrinsic impurities and extrinsic impurities.

[0036] There is also a need for a process capable of treating an input waste material comprising at least one polymer fraction, the input waste material having an initial content of intrinsic impurities, preferably for removing intrinsic impurities from an input waste material to obtain an output waste material complying with ongoing sustainability and regulative requirements.

Summary of the Invention

[0037] This problem is solved by the subject-matter of independent claims 1, and 4. Further aspects and preferred aspects of the present invention are defined in the process, product claims and use claims as well as in the dependent claims and result from the following description, and the appended examples.

[0038] The term “basic” in the patent application encompasses the wording “alkaline” or “caustic”.

[0039] An aspect of a process for treating an input waste material is taught in this disclosure. The input waste material comprises at least one polymer fraction. The input waste material has an initial content of intrinsic impurities located in the at least one polymer fraction.

[0040] The term “intrinsic impurities” refers to discrete impurities that are integrated into the input waste material. In other words, the intrinsic impurities are incorporated, i.e., embedded into the input waste material. The term “intrinsic impurities” further refers to impurities, i.e., contaminants, embedded in the at least one polymer fraction. In other words, the intrinsic impurities may be trapped in the at least one polymer fraction.

[0041] The term “intrinsic impurities” further encompasses non-intentionally added substances (NIAS) and intentionally added substances (IAS).

[0042] The NIAS may refer to degradation products of recyclates. The NIAS may refer to breakdown products from recycling of low-density polyethylene (LDPE), such as oxidized degradation products. The NIAS may refer to degradation products originating from a recycling of materials and/or from the life cycle of the materials.

[0043] In one aspect, the NIAS is selected from oxidized degradation products from recycling of LDPE, and/or impurities from polyurethane (PU) adhesives.

[0044] In one aspect, the NIAS is selected from oligomers; and/or the impurities from polyurethane (PU) adhesives are amines.

[0045] In one aspect, the NIAS is hexadecanoic acid.

[0046] In one aspect, the process is for removing intrinsic impurities from the input waste material. In one aspect, the process is for decontaminating the input waste material.

[0047] In one aspect, the intrinsic impurities are comprised of one of organic compounds, such as organic volatile compounds and/or inorganic compounds.

[0048] In one aspect, the intrinsic impurities are comprised of one of organic compounds, such as organic volatile compounds (VOC), and/or inorganic compounds.

[0049] In one aspect, the intrinsic impurities are comprised of one of monomers, oligomers, phosphates, phenols, ink particles, pigments particles, metal ions, titanium dioxide (TiCh), iron oxide, zinc oxide, sodium stearate, calcium stearate, varnish particles, organic solvents, or a combination thereof.

[0050] The process comprises acid washing the input waste material with an acidic solution, followed by removing the acidic solution comprising at least part of intrinsic impurities, thereby obtaining an acid washed output waste material, and mixing a non-solvent in a liquid state with the acid washed output waste material in an apparatus for forming an azeotrope mixture of the non-solvent with intrinsic impurities, followed by outputting at least part of intrinsic impurities in a gaseous state from the apparatus, thereby obtaining an acid washed mixed output waste material.

[0051] In one further aspect, the acidic solution comprises a carboxylic acid. [0052] In one further aspect, the carboxylic acid is comprised of one of methanoic acid or ethanoic acid.

[0053] The acid washing of the input waste material, such as a polymer recyclate, is uncommon. Organic acids, i.e., carboxylic acids can, in particular, diffuse into the polymer fraction and can lead to a degradation of the polymer fractions if the carboxylic acids are not properly removed before further manufacturing processes, like extrusion. Therefore, the person skilled in the art would not think about conducting an acid washing on an input waste material.

[0054] The inventors further surprisingly found out that the step of the acid washing enables improving the treating of the input waste material, and in particular, enables improving the removing of intrinsic impurities.

[0055] It would have been counterintuitive for the person skilled in the art to conduct the acid washing of the input waste material comprising at least one polymer fraction, such as plastic, as the person skilled in the art would rather get acids out of the input waste material. Remaining contents of acids would hamper subsequent processing, like extrusion, if the acids are still present in the input waste material.

[0056] In one aspect, the acid washed output waste material has a reduced content of intrinsic impurities relative to the initial content of intrinsic impurities.

[0057] In one further aspect, the acid washed output waste material has a content of intrinsic impurities reduced by a factor of 10, more preferably by a factor of 100, relative to the initial content of intrinsic impurities.

[0058] In one aspect, the acid washing is conducted at a temperature of at least 50°C. In one further aspect, the acid washing is conducted at a temperature between 60°C and 100°C, such as 70°C. In another aspect, the acid washing is conducted for at least 120 min, such as for 240 minutes.

[0059] In one aspect, the input waste material has an initial content of extrinsic impurities.

[0060] In one aspect, the extrinsic impurities are selected from one of ink particles, pigments particles, varnish particles, or a combination thereof.

[0061] In one aspect, the process comprises basic washing the acid washed output waste material with a basic solution after the acid washing, followed by removing the basic solution comprising at least part of intrinsic impurities, thereby obtaining an acid basic washed output waste material. [0062] In one aspect, the basic solution comprises at least 6 wt.% of sodium hydroxide respective to the basic solution.

[0063] In one aspect, the basic solution comprises at least 8 wt.% respective to the basic solution.

[0064] In one further aspect, the basic washing is conducted at a temperature of at least 100°C, for example, at a temperature between 60°C and 70°C, in a further example, at 70°C, and/or for at least 30 minutes, for example, between 30 minutes and 140 minutes, in a further example between 60 min and 140 minutes.

[0065] The inventors found out surprisingly that the basic washing enables to improve the treating of the input waste material, and in particular, enables the removing of the intrinsic impurities from the input waste material for further processing, as well as enables the removing of the extrinsic impurities from the input waste material.

[0066] The inventors found out that the basic washing enables to remove extrinsic impurities made of color particles. Thus, treating the input waste material comprising the step of the basic washing impacts the color of resulting obtained waste material, such as the acid basic washed output waste material. For example, the inventors found out that the removed extrinsic impurities from the input waste material having a green color, results in an acid basic washed output waste material substantially transparent.

[0067] The inventors found out a surprising effect of conducting at least one basic washing at the specific conditions of the basic solution comprising at least 6 wt% and at the temperature of at least 50°C. The specific conditions of the basic washing result in an improved removing of the extrinsic impurities, such as inks. The inventors found out a synergetic effect of a basic solution with a content of at least 6 wt% at a temperature of at least 50°C, even more with a basic solution with a content of at least 8 wt% at a temperature of 70°C. The inventors provide below theories explaining this synergetic effect, but the inventors are not bound to these theories. A theory explaining this synergetic effect could be that some extrinsic impurities, such as ink particles comprising functional groups, are partially hydrolyzed and there is an attack of the sodium hydroxide on the functional groups. Increasing the temperature combined with increasing the content of the sodium hydroxide surprisingly results in accelerating the hydrolyzation reaction, thus the treating. The inventors showed that surprisingly, increasing the temperature combined with increasing the content of the sodium hydroxide leads to better treating the input waste material than increasing only the temperature or increasing only the content of the sodium hydroxide. A further theory could be that the basic washing also enables removing intrinsic impurities such as calcium stearate. Calcium stearate has a low solubility in water. The calcium from the calcium stearate in presence of the basic solution comprising sodium hydroxide is replaced by the sodium ion of the sodium hydroxide, thus the solubility of the calcium stearate is increased, i.e., the transportability of the calcium stearate is improved, i.e., the extraction of the calcium stearate into the basic solution is improved. The inventors are not bound to this theory.

[0068] The person skilled in the art would further have oriented himself at the typical basic washing known for PET recycling with a basic solution comprising sodium hydroxide in the range of 0,5 to 5 wt.% maximum and not the basic washing claimed in the present invention. [0069] The person skilled at the art would have identified that a higher sodium hydroxide content would bear many operational disadvantages with an only slight impact on further qualitative improvement of the basic washing. The operational disadvantages are, for example, higher contents of chemicals, a need to adapt some materials to have corrosion resistance, e.g. for steel, higher contents of washing water to neutralize the pH value of the basic solution, or a higher effort in treating wastewater. In addition, a basic solution comprising sodium hydroxide with 3.9 wt% has a pH value of 14. i.e., the highest pH value possible. The person skilled in the art would not expect any supplementary effect and would have expected no contribution of an addition of more sodium hydroxide to the basic solution having a pH of already 14. The person skilled in the art would be prevented into using a basic solution with a content of at least 6 wt%, knowing that a basic solution between 0.5 and 5 wt.% is already sufficient for removing intrinsic impurities and would not have considered going beyond 5 wt.%. Therefore, the inventors provided a great contribution over the prior art by using a basic solution comprising sodium hydroxide of at least 8wt.%, and preferably at a high temperature, i.e., at 70°C.

[0070] The inventors further found out that subsequent basic washing, i.e., a basic washing conducted on cascade on the input waste material or on the output waste material, is even more efficient than conducting only one basic washing.

[0071] It is to be noted that not only the basic washing can be foreseen as subsequent washings, i.e., a cascade system of washings, but the acid washing as well may comprise subsequent washing. [0072] The inventors found out that the acid washing, followed by the basic washing, results in an improved treating, i.e., treatment, i.e., decontamination, especially, for removing intrinsic impurities. Indeed, intrinsic impurities consisting of amines and acids cannot be removed from an input waste material by conducting a single-stage process. Amines are not captured during the acid washing. Acids are not captured by the basic washing due to the formation of salts that cannot diffuse through the polymer matrix that is non-polar., conducting the acid washing, followed by the basic washing are complementary to each other and results in an improved removing of intrinsic impurities in comparison to conducting only the acid washing, or conducting only the basic washing, respectively.

[0073] It is preferred to conduct the acid washing, followed by the basic washing, on an input waste material comprising aluminium. This order enables delaminating aluminium, i.e., separating aluminium from additional fractions comprising aluminium in the input waste material. To conduct the basic washing, followed by the acid washing, in this order, on the input waste material comprising aluminium would result in an unfavored side reaction between the base of the basic solution and the aluminium. This reaction would produce high contents of hydrogen, resulting in highly risked safety problems.

[0074] In one aspect, the basic washing is conducted prior to the acid washing, thereby obtaining a basic acid washed output waste material, followed by the mixing, thereby obtaining a basic acid washed mixed output waste material.

[0075] The order of the acid washing and the basic washing can be changed, for example, for any industrial reasons or based on the chemical composition of the input waste materials. [0076] It should be however understood that for an input waste material with no aluminium, the acid washing can be followed by the basic washing, or vice versa, for example, if there are no unexpected side reactions predictable and that the order do not imply risked safety problems.

[0077] A further process for treating an input waste material is further disclosed. The input material comprises at least one polymer fraction and has an initial content of intrinsic impurities located in the at least one polymer fraction. The process comprises at least basic washing the input waste material with a basic solution, followed by removing the basic solution comprising at least part of the intrinsic impurities, thereby obtaining a basic washed output waste material, and mixing a non-solvent in a liquid state with the basic washed output waste material in an apparatus for forming an azeotrope mixture of the non-solvent with intrinsic impurities, followed by outputting at least part of intrinsic impurities in a gaseous state from the apparatus, thereby obtaining a basic washed mixed output waste material.

[0078] In one aspect, the mixing with the non-solvent in a liquid state is conducted in the apparatus at a temperature between 110 °C and 330 °C, and/or a pressure between 10 and 300 bar, and/or a water content below 5 % respective to the mass of an input material added into the apparatus. It is to be noted that the parameters for the mixing can be at least one of the temperature, the pressure, or the water content indicated above, or at least two of the parameters indicated above, or the three parameters indicated above.

[0079] In one aspect, the apparatus is an extruder. Thus, the step of mixing is an extrusion step comprising extruding the non-solvent in a liquid state with the acid washed output waste material, the acid basic washed output waste material, the basic acid washed output waste material, or basic washed output waste material in the extruder for forming an azeotrope mixture of the non-solvent with the intrinsic impurities. In this aspect, the acid washed mixed output waste material is an acid washed extruded output waste material. The acid basic washed mixed output waste material is an acid basic washed extruded output waste material. The basic acid washed mixed output waste material is a basic acid washed extruded output waste material. The basic washed mixed output waste material is a basic washed extruded output waste material.

[0080] The non-solvent is injected into the apparatus, such as an extruder, in the liquid state, which enables a homogeneous dispersion in a liquid state of the non-solvent with the acid washed output waste material, the acid basic washed output waste material, the basic acid washed output waste material, or the basic washed output waste material. The surprising effect comes from the fact that the non-solvent is injected in the liquid phase and not in the gaseous phase, as the person skilled in the art would normally think about. The formation of the homogeneous dispersion of the non-solvent with the acid washed output waste material, the acid basic washed output waste material, the basic acid washed output waste material, or the basic washed output waste material, enables simultaneously the extraction of the intrinsic impurities from the acid washed output waste material, the acid basic washed output waste material, the basic acid washed output waste material, or the basic washed output waste material, and the obtention of a gaseous phase comprising the intrinsic impurities and the non-solvent. There is thus no need to apply two separate sub steps in the step of extruding to separate firstly the intrinsic impurities from the acid washed output waste material, the acid basic washed output waste material, the basic acid washed output waste material, or the basic washed output waste material, and subsequently to evaporate the intrinsic impurities and the non-solvent.

[0081] Thus, the process comprising the step of the mixing enables the use of elevated temperatures and pressures which means that transport mechanism to remove the nonsolvent with the intrinsic impurities is accelerated. The reduction in the number of sub steps in the step of mixing, such as extruding, means that the method takes less time to carry out and so less non-solvent, or a small amount of the non-solvent, is needed to achieve the extraction of the intrinsic impurities. The substantially homogeneous mixing of the nonsolvent with the acid washed output waste material, the acid basic washed output waste material, the basic acid washed output waste material, or the basic washed output waste material, enables quick process times. The process comprising the step of mixing, such as extruding, requires only a small amount of non-solvent, and therefore has economic advantages and also ecological advantages.

[0082] The step of the mixing further results in a compacting the acid washed output waste material, the acid basic washed output waste material, basic acid washed output waste material, or the basic washed output waste material, being, for example, initially in form of flakes. This compacting results in obtaining the acid washed mixed output waste material, the acid basic washed mixed output waste material, the basic acid washed mixed output waste material, or the basic washed mixed output waste material, with a lower specific surface. If the acid washing and/or the basic washing would be conducted after this step, the acidic solution and/or the basic solution would not be able to efficiently further treat, or extract, the specific surface of the mixed output waste material that would be obtained from the mixing step..

[0083] The acid washing and the basic washing take place in aqueous solutions, i.e., polar media. Non-polar contaminants could therefore not be removed after conducting the acid washing and/or the basic washing. The inventors found surprisingly that the mixing of the non-solvent in a liquid state with the acid washed output waste material, the acid basic washed output waste material, the basic acid washed output waste material, or the basic washed output waste material to form an azeotrope mixture, i.e., conducting an extrusion step, is advantageous to obtain the acid washed mixed output waste material, the acid basic washed mixed output waste material, the basic acid washed mixed output waste material, or the basic washed mixed output waste material with an improved reduced residual content of intrinsic impurities, i.e., intrinsic contaminants.

[0084] In one further aspect, the inventors found surprisingly that the mixing of the further enables removing intrinsic impurities made of odorous molecules, therefore reducing the odor of the acid washed output waste material, the acid basic washed output waste material, the basic acid washed output waste material, or the basic washed output waste material.

[0085] In one aspect, the acid washed output waste material, the acid basic washed output waste material, the basic acid washed output waste material, and/or the basic washed output waste material have a reduced content of intrinsic impurities relative to the initial content of intrinsic impurities.

[0086] In one further aspect, the acid washed output waste material, the acid basic washed output waste material, the basic acid washed output waste material, or the basic washed output waste material, have a content of intrinsic impurities reduced by a factor of 10, more preferably by a factor of 100, relative to the initial content of intrinsic impurities.

[0087] In one aspect, the extrusion step target, i.e., enables removing organic compounds with a boiling point up to 400 °C. The VVOCs have a boiling point lower than 100 °C. The extrusion step further enables removing VOCs. The VOCs have a boiling point between 100 and 260 °C. The extrusion step further enables removing semi-volatile organic compounds (SVOCs). The SVOCs have a boiling point between 260 °C and 400 °C.

[0088] The inventors further found out that conducting an acidic washing, and/or basic washing, followed by mixing the non-solvent in a liquid state with the output waste material for forming the azeotrope mixture, results in an improved removing of intrinsic impurities and extrinsic impurities.

[0089] The inventors found out that conducting subsequent acid washing and/or basic washing and/or extruding in one process results in improving the decontamination of the input waste material.

[0090] Each step of the process, i.e., treating step, enables removing one class of intrinsic impurities, for example, organic compounds, or inorganic compounds. The acid washing lacks, for example, removing amines due to a formation of ammonium salt, whereas the basic washing lacks, for example, removing acids due to a formation of carboxylates. On the contrary, the extrusion process with mixing the non-solvent in a liquid state with the output waste material for forming an azeotrope mixture lacks removing, for example, non-organic intrinsic impurities, like salts and metal ions, or lacks removing non-volatile components, like ink particles.

[0091] Furthermore, the process comprises subsequent steps, i.e., cascade type steps, enables decreasing the amount of intrinsic impurities, i.e., the intrinsic contaminants, stepwise. Single steps, on the contrary, can easily be overloaded and thus the single steps worsen the efficiency of removing intrinsic impurities, i.e., worsen the efficiency of decontaminating the input waste material.

[0092] In a further aspect, the at least one polymer fraction comprises polyethylene, for example, low-density polyethylene, and/or the input waste material comprises at least one paper fraction, and/or the input waste material comprises at least one metal fraction, preferably the at least one metal fraction comprises aluminium.

[0093] In a further aspect, the input waste material is one of a post-consumer waste, a recycled polymer, or a used beverage carton (UBC).

[0094] In a further aspect, the non-solvent comprises at least one of water, a base, preferably the base is selected from one of ammonia or pyridine; an alcohol, preferably the alcohol is selected from one of methanol, ethanol, or isopropanol, carbon dioxide, preferably carbon dioxide and water, more preferably the carbon dioxide is at a content between 10% and 50% by weight respective to the water, or a combination thereof.

[0095] It was a surprising result that the water of the non-solvent was able to remove the intrinsic impurities as the prior art had indicated that the use of water in recycled plastics did not enable a sufficiently fine dispersion of the water in recycled plastics to enable this removal. The carbon dioxide acts as a cosolvent, which improves the dissolution. The use of the carbon dioxide over alternative acidic component or basic component is ecologically more favourable as carbon dioxide is easily removed from the melts. Furthermore, the carbon dioxide leaves no residues in the extruded plastics which might cause issues when products made from the extruded plastics are brought into contact with living agents.

[0096] In one aspect, the process enables to treat an input waste material having a higher initial content of extrinsic impurities than the output waste material, preferably the extrinsic impurities are selected from one of ink particles, pigments particles, varnish particles, or a combination thereof. Indeed, the process has proven particularly well suited to reducing if present ink particles, pigments particles, varnish particles, or a combination thereof as extrinsic on surface located impurities or intrinsic impurities beneath the polymer surface. The content of these impurities is reduced by a factor of 10, more preferably by a factor of 100, relative to the initial content of initial impurities, preferably the reduction is valid both for intrinsic and extrinsic impurities. It is to be noted that deinking might even be obtained in a process using only basic washing without acid washing.

[0097] A material obtained by a process according to any of the preceding aspects is taught in this disclosure, in particular one of one of an acid washed mixed output waste material, an acid basic washed mixed output waste material, basic acid washed mixed output waste material, and a basic washed mixed output waste material, made of a recycled polymer comprising at least one polymer fraction, preferably made of PE. The material has a residual content of intrinsic impurities of intentionally added substances (IAS) of below 10 ppm, preferably below 3 ppm, and a residual content of non-intentionally added substances (NIAS) selected from oligomers below 200 ppm.

[0098] In one aspect, the IAS is tris(2,4-di-tert-butylphenyl) phosphite. The tris(2,4-di-tert- butylphenyl) phosphite can be added as stabilizer.

[0099] In one aspect, the NIAS is hexadecanoic acid.

[00100] A use of the material of the above aspect, in particular one of an acid washed mixed output waste material, an acid basic washed mixed output waste material, basic acid washed mixed output waste material, and a basic washed mixed output waste material, in a consumer package, preferably for food application, is taught in this disclosure.

of the figures

[00101] The invention is described hereinafter with reference to the enclosed figures, in which:

[00102] Figs. 1, 2, 3, 4, 5A, 6, 7, 8 and 9 show process schemes of different aspects of a process for treating an input waste material having an initial content of intrinsic impurities.

[00103] Fig. 5B shows a view of an apparatus for removing intrinsic impurities.

[00104] Fig. 10 shows an input waste material with intrinsic impurities and extrinsic impurities. Detailed of the invention

[00105] The invention will now be described on the basis of the drawings. It will be understood that the aspects and aspects of the invention described herein are only examples and do not limit the protective scope of the claims in any way. The invention is defined by the claims and their equivalents. It will be understood that features of one aspect or aspect of the invention can be combined with the feature of a different aspect or aspects and/or aspects of the invention.

INPUT WASTE MATERIAL

[00106] The present invention discloses a process for treating an input waste material 10. For example, the process is a process for removing intrinsic impurities 15 from an input waste material 10.

[00107] In one example, the input waste material 10 is selected from one of a post-industrial waste (PIR) or a post-consumer waste (PCR). In a preferred example, the input waste material 10 is a PCR.

[00108] The input waste material 10 comprises at least one polymer fraction.

[00109] In one example, the at least one polymer fraction comprises polyolefins, preferably the polyolefins are polyethylene (PE), more preferably the PE is a low-density polyethylene (LDPE).

[00110] In a further example, the input waste material 10 is a PCR and comprises at least one polymer fraction comprising polyolefins (PCR-polyolefins). In a further example, the input waste material 10 is a PCR and comprises at least one polymer fraction comprising LDPE (PCR-LDPE).

[00111] In a further example, the input waste material 10 originates from a used beverage carton (UBC).

[00112] In one example, the input waste material 10 from the UBC comprises a first polymer fraction, a second polymer fraction, a third polymer fraction, a paper fraction and a metal fraction.

[00113] In a further example, the input waste material 10 from the UBC comprises a first polymer layer, a second polymer layer and a third polymer layer comprising the first polymer fraction, the second polymer fraction and the third polymer fraction, respectively. In this example, the input waste material 10 from the UBC comprises a paper layer comprising the paper fraction, preferably the paper fraction comprises a cellulose-based fraction. In this example, the input waste material 10 from the UBC further comprises a metal layer comprising the metal fraction, preferably the metal fraction comprises aluminium.

[00114] In a further example, the first polymer layer is bonded to the paper layer, the paper layer is bonded to the second polymer layer, the second polymer layer is bonded to the metal layer, the metal layer is bonded to the third polymer layer. Bonding agents are, for example, used between the first polymer layer, the paper layer, the second polymer layer, the metal layer and the third polymer layer. Such bonding agents include, but are not limited to, ethylene/acrylic acid copolymer, called tie layers and/or polyurethane adhesives.

[00115] The input waste material 10 comprises intrinsic impurities 15.

[00116] In one example, intrinsic impurities 15 have a molecular mass above 250 g/mol.

[00117] In one example, intrinsic impurities 15 are comprised of one of organic compounds, such as organic volatile compounds (VOC) and/or inorganic compounds, preferably intrinsic impurities 15 are comprised of one of monomers, oligomers, amine, acids, phosphates, phenols, ink particles, pigments particles, metal ions, titanium dioxide (TiCh), iron oxide, zinc oxide, sodium stearate, calcium stearate, varnish particles, organic solvents, or a combination thereof, more preferably intrinsic impurities 15 are ink particles.

[00118] In one example, the intrinsic impurities 15 are located in the at least one polymer fraction, as shown on Fig. 10. The intrinsic impurities 15 are, for example, amine, or acid, such as carboxylic acid.

[00119] In one example, the input waste material 10 comprises extrinsic impurities 20. The extrinsic impurities are, for example, one of ink particles, pigments particles, varnish particles, or a combination thereof.

[00120] In another example, the extrinsic impurities 20 are located on the at least one polymer fraction, as shown on Fig. 10. The extrinsic impurities 20 are, for example, ink particles.

PROCESS Acid washing - 1

[00121] In a first aspect shown in Fig. 1, the process for treating the input waste material 10 comprises at least one acid washing SI 00 of the input waste material 10 with an acidic solution 70.

[00122] The at least one acid washing S100 is conducted, for example, at a temperature of at least 50°C, preferably at a temperature between 60°C and 100°C, more preferably at 70°C. [00123] The at least one acid washing S100 is conducted, for example, for at least 120 min, preferably for 240 minutes.

[00124] In one example, the acidic solution 70 comprises a carboxylic acid, more preferably the carboxylic acid is selected from one of methanoic acid, i.e., formic acid, or ethanoic acid, i.e., acetic acid.

[00125] In one example, the acidic solution 70 comprises at most 60 wt.% of carboxylic acid. The acidic solution 70 comprises, in a further example, up to 30 w-% of carboxylic acid. The acidic solution 70 comprises, in another example, up to 10 w-% of carboxylic acid. [00126] The acidic solution 70 is, for example, a formic acid water solution.

[00127] In a further example, the acidic solution 70 comprises additives, e.g. alkyl sulfates as anionic surfactants, for an improvement of a wetting of the input waste material 10, or additives, e.g., sodium formiate and sodium dihydrogen phosphate for a protection of material components of the input waste material 10, such as the aluminium fraction.

[00128] The at least one acid washing S100 is followed by removing S150 the acidic solution 70 comprising at least part of the impurities 15, thereby obtaining S400 an acid washed output waste material 110.

[00129] The removed acidic solution 70 is, for example, used for further material treatments. [00130] The process comprises, for example, two subsequent acid washings S100 of the input waste material 10.

[00131] The obtained output waste material 110 is optionally washed with water to neutralize the pH value.

[00132] In one example, the obtained output waste material 110 is washed with water to reach a pH of at least 4.

[00133] In one example, the acid washed output waste material 110 has a reduced content of intrinsic impurities relative to the initial content of intrinsic impurities. Basic washing - 2

[00134] In a second aspect shown in Fig. 2, the process for treating the input waste material 10 comprises at least one basic washing S200 the input waste material 10 with a basic solution 80.

[00135] The at least one basic washing S200 of the input waste material 10 is conducted, for example, at a temperature of at least 50°C, preferably at a temperature between 60°C and 100°C, more preferably at 70°C.

[00136] The at least basic washing S200 is conducted, for example, for 60 minutes, i.e., one hour, or 120 min, or 240 minutes, i.e., for 4 hours.

[00137] In one example, the basic solution 80 comprises sodium hydroxide, preferably at least more than 5 wt%, more preferably at least 6 wt%. of sodium hydroxide, most preferably at least 8 wt.%, respective to the basic solution 80. In one illustrative example, the basic solution 80 comprises between 8 wt.% and 10 wt.% of sodium hydroxide.

[00138] The basic solution 80 has, in one example, a pH of 14.

[00139] In a further example, the basic solution 80 comprises additives, e.g. cationic ammonium salts as cationic surfactants, for improving a wetting of the input waste material 10.

[00140] The at least one basic washing S200 is followed by removing S250 the basic solution 80 comprising at least part of the impurities 15, thereby obtaining S400 a basic washed output waste material 210.

[00141] The removed basic solution 80 is, for example, used for further material treatments. [00142] The process comprises, for example, two subsequent basic washing S200 of the input waste material 10. For example, the two subsequent basic washing S200 are conducted subsequently for one hour.

[00143] The obtained output waste material 210 is optionally washed with water to neutralize the pH value.

[00144] In one example, the obtained output waste material 210 is washed with water to reach a pH of at least 9.

[00145] In one example a loading degree is determined to encompass an input waste material 10 with a substantial fluffy shape.

[00146] In one example, the basic washed output waste material 210 has a reduced content of intrinsic impurities relative to the initial content of intrinsic impurities. [00147] In one example, a loading degree of the input waste material 10 is at most a 5% loading degree, i.e., 5 g of the input waste material 10 in 100 g of a basic solution 80 comprising sodium hydroxide. In a further example, a loading degree of the input waste material 10 is at most a 2.5% loading degree, i.e., 100 g of the input waste material 10 in 4 kg g of a basic solution 80 comprising sodium hydroxide. A low loading degree enables a re-distribution of localized contaminant, i.e., intrinsic impurities 15, in the input waste material 10, into a homogenously distribution over the whole system, i.e., the basic solution 80 solution with the input waste material 10.

[00148] In one example, the input waste material 10 made of pure LDPE flakes from used beverage cartons, the removed intrinsic impurities 15 are obtained as a green fine solid comprising ink particles and calcium stearate. The removed intrinsic impurities 15 are optionally filtered out.

[00149] In one example, an efficiency of the removing of intrinsic impurities 15, i.e., the quality of the decontamination, is evaluated by balancing out the removed intrinsic impurities 15. The efficiency of the process for removing intrinsic impurities is qualified as efficient, i.e., with a good decontamination efficiency, with a content between 0,5% and 3% of removed, i.e., isolated intrinsic impurities, i.e., contaminants 15, preferably a content between 1 and 2%.

[00150] In other example, the process comprises three subsequent basic washing S200 of the input waste material 10. For example, the three subsequent basic washing S200 are conducted subsequently for one hour.

[00151] In another example, the efficiency of the removing of intrinsic impurities 15, i.e., the quality of the decontamination, is evaluated by plasticizing the basic washed output waste material 210. The basic washed output waste material 210 is then characterized by the color and the transparency improvement between before the process and after the process.

Acid washing - 1, followed by Basic washing - 2

[00152] In a third aspect shown in Fig. 3, the process for treating the input waste material 10 comprises at least one acid washing SI 00 of the input waste material 10, thereby obtaining the acid washed output waste material 110, followed by at least one basic washing S200 of the acid washed output waste material 110 with a basic solution 80. [00153] The at least one acid washing S100 may be conducted according to the process described in Fig. 1, to come up with the acid washed output waste material 110.

[00154] The at least one basic washing S200 of the acid washed output waste material 110 is conducted, for example, at a temperature of at least 50°C, preferably at a temperature between 60°C and 100°C, more preferably at 70°C.

[00155] The at least basic washing S200 is conducted, for example, for 60 minutes, i.e., one hour, or 120 min, or 240 minutes, i.e., for 4 hours.

[00156] In one example, the basic solution 80 comprises sodium hydroxide, preferably at least more than 5 wt%, more preferably at least 6 wt%. of sodium hydroxide, most preferably at least 8 wt.%, respective to the basic solution 80. In one illustrative example, the basic solution 80 comprises between 8 wt.% and 10 wt.% of sodium hydroxide.

[00157] The basic solution 80 has, in one example, a pH of 14.

[00158] In a further example, the basic solution 80 comprises additives, e.g. cationic ammonium salts as cationic surfactants, for improving a wetting of the input waste material 10.

[00159] The at least one basic washing S200 is followed by removing S250 the basic solution 80 comprising at least part of the impurities 15, thereby obtaining S400 an acid basic washed output waste material 220.

[00160] In one example, the input waste material 10 made of pure LDPE flakes from used beverage cartons, the removed intrinsic impurities 15 are obtained as a green fine solid, comprising ink particles and calcium stearate. The removed intrinsic impurities are optionally filtered out.

[00161] In one example, the acid basic washed output waste material 220 has a reduced content of intrinsic impurities relative to the initial content of intrinsic impurities.

[00162] In one example, the efficiency of the removing of intrinsic impurities 15, i.e., the quality of the decontamination, is evaluated by balancing out the removed intrinsic impurities 15. A good decontamination efficiency is represented by a content between 0,5- 3% of the removed, i.e., isolated intrinsic impurities, i.e., contaminants 15, preferably a content between 1 and 2%.

[00163] In another example, the efficiency of the removing of intrinsic impurities 15, i.e., the quality of the decontamination, is evaluated by the color and transparency improvement. [00164] In one example, the acid washing SI 00 is preferably followed by the basic washing S200 for an input waste material 10 with a multilayer structure and comprising the aluminium fraction.

[00165] The acid washing SI 00 enables to facilitate a delamination of the aluminium fraction out of the multilayer structure. A first step of acid washing SI 00 the aluminium fraction further enables isolating the aluminium fraction before the basic washing S200.

[00166] The basic washing S200 is sensitive to high contents of non-preci ous metals like aluminium because aluminium is dissolved by oxidative corrosion under hydrogen gas evolution. The isolation of the aluminium fraction before the basic washing S200 improves safety conditions of the basic washing S200.

[00167] The acid washing in step SI 00, followed by the basic washing in step S200, enables to obtain in step S400 an improved acid basic washed output waste material 220. The acid basic washed output waste material 220 is an improved quality recycled polymer.

Basic washing - 2, followed by Acid washing - 1

[00168] In a fourth aspect shown on Fig. 4, the basic washing S200 is conducted prior to the acid washing SI 00.

[00169] In the fourth aspect, the step of acid washing S100 is conducted on the basic washed output waste material 210, thereby obtaining a basic acid washed output waste material 225. The intermediate basic washed output material 210 fulfills the same characteristics as in the aspect “Basic washing - 2”.

[00170] In one example, the basic acid washed output waste material 225 has a reduced content of intrinsic impurities relative to the initial content of intrinsic impurities.

[00171] The basic washing in step S200, followed by the acid washing in step SI 00, enables to obtain in step S400 an improved basic acid washed output waste material 225. The basic acid washed output waste material 225 is an improved quality recycled polymer.

Acid washing - 1, followed by forming an azeotrope mixture of a non-solvent with intrinsic impurities - 3

[00172] In a fifth aspect shown on Fig. 5 A, the process for treating the input waste material 10 comprises at least one acid washing SI 00 of the input waste material 10, thereby obtaining the acid washed output waste material 110, followed by mixing S350 a non-solvent 90 in a liquid state with the acid washed output waste material 110 in an apparatus 100 for forming an azeotrope mixture of the non-solvent 90 with intrinsic impurities 15.

[00173] In one example, the apparatus 100 shown in Fig. 5B is an extruder, more preferably a single-screw extruder. The extruder 100 comprises a housing 62 with a mixing element 170, a heating device 180, an output device 190, and a material outlet 195.

[00174] The non-solvent 90 in the liquid state may comprise at least one of water, a base, preferably the base is selected from one of ammonia or pyridine, an alcohol, preferably the alcohol is selected from one of methanol, ethanol, or isopropanol, carbon dioxide, preferably carbon dioxide and water, more preferably the carbon dioxide is at a content between 10% and 50% by weight respective to the water, or a combination thereof.

[00175] In order to perform the mixing step in the extruder 100, the acid washed output waste material 110 is fed in the extruder, i.e., introduced in a step 300, through a hopper 15 into the housing 62.

[00176] The acid washed output waste material 110 is melted S310 using the heating device 180. The rotation of the mixing element 170 forwards the acid washed output waste material 110 in a melted state through the apparatus 100. The temperature inside the housing 62 increases due to the work done on the acid washed output waste material 110 by rotation of the mixing element 170 and the heating of the housing 62 by the heating device 180.

[00177] For example, the temperature inside the housing 62 is between 110 °C and 330 °C, and in a further aspect between 200°C and 230°C. For example, the temperature inside the housing is between 130°C and 230°C, between 180°C and 230°C, between 250°C and 290°C or between 250°C and 310°C. The temperature inside the housing 62 is, for example, 160°C. The increase of the temperature causes an increase of the pressure inside the housing 62.

[00178] The pressure inside the housing 62 can be, for example, between 2 and 300 bar. The pressure inside the housing 62 is, for example, between 10 and 300 bar. The pressure inside the housing 62 is, for example, below 40 bar. The pressure inside the housing 62 is dependent on the nature of the acid washed output waste material 110, the nature of the non-solvent 90, the temperature inside the housing 62 and the rotation per minute of the mixing element 170. The pressure is chosen so that non-solvent 90 does not evaporate in the housing 62 but remains in a liquid state. The elevated temperatures and the high pressure in the apparatus enable to speed up the method for extruding an acid washed mixed output waste material 310 from the acid washed output waste material 110. The term "high pressure" means the pressure must be applied to prevent evaporation of the non-solvent 90 in the injection zone at the respective process temperature

[00179] In a step S320, the non-solvent 90 in a liquid state is injected into the apparatus 100 through an injector 160. The non-solvent 90 is injected into the apparatus 100 at a pressure so that the pressure inside the housing 62 of the apparatus 100 is above the vapor pressure of the non-solvent 90. At this pressure in the apparatus 100, the non-solvent 90 is inside the housing 62 in the liquid state, preventing the formation of foam inside the apparatus 100 and enabling the homogeneous mixing 350 of the non-solvent 90 and the acid washed output waste material 110.

[00180] In one example, the water content in the apparatus 100 is below 5 % respective to the mass of the acid washed output waste material 110 added into the apparatus 100. In one further example, the water content in the apparatus 100 is below 3 %. In one further example, the water content in the apparatus 100 is below 2%, for example 1,8 %.

[00181] In one example, the temperature inside the housing 62 of the apparatus 100, for example the extruder, is between 110 °C and 330 °C, and/or the pressure inside the housing 62 of the apparatus is between 10 and 300 bar, and/or the water content in the apparatus 100 is below 5 % respective to the mass of the acid washed output waste material 110 added into the apparatus 100.

[00182] In one example, at least two of the temperature, the pressure, and the water content, in the apparatus 100, are selected in the above mentioned ranges. In one example, the temperature, the pressure, and the water content, in the apparatus 100, are selected in the above mentioned ranges.

[00183] The non-solvent 90 and intrinsic impurities 15 form an azeotrope mixture.

[00184] The term “azeotrope mixture” means a mixture in which the mole fractions of all components in the liquid state are equal to the mole fractions of all components in the vapor state.

[00185] The homogeneous mixing 350 of the non-solvent 15 and the acid washed output waste material 110 enables a better absorption of the impurities 15 in the non-solvent 90 because the length of diffusion in the homogenous mixture is small and thus facilitates a removing of the impurities 15 from the acid washed output waste material 110. The nonsolvent 50 is injected into the apparatus 10 at a pressure, for example, of 3 to 90 bar, and in one further example, between 50 and 80 bar. [00186] At the output of the apparatus 100, the pressure inside the housing 62 decreases, enabling the impurities 15 in the non-solvent 90 to pass from the liquid state into the gaseous state.

[00187] In step 370, intrinsic impurities 15 are output in a gaseous state from the apparatus 100 at the output device 190. In one aspect, intrinsic impurities 15 in the gaseous state are output 370 in a vacuum from the apparatus 100. This (partial) vacuum is created for example by using a water ring vacuum pump. Outputting 370 intrinsic impurities 15 in the gaseous state in a vacuum enables a better extraction of intrinsic impurities 15 from the acid washed output waste material 110 into the non-solvent 90.

[00188] A melted acid washed mixed output waste material 310 is forced through the material outlet 195 of the apparatus 100, thereby obtaining in a step 400 an acid washed mixed output waste material 310.

[00189] In one aspect, the acid washed mixed output waste material 310 has a reduced residual content of intrinsic impurities 15 relative to the initial content of intrinsic impurities. [00190] The at least one acid washing S 100 of the input waste material 10, thereby obtaining the acid washed output waste material 110, followed by the mixing S350 of the non-solvent 90 in the liquid state with the acid washed output waste material 110 in the apparatus 100 for forming the azeotrope mixture of the non-solvent 90 with intrinsic impurities 15 enables to obtain an improved acid washed mixed output waste material 310. The acid washed mixed output waste material 310 is an improved quality recycled polymer.

Acid washing - 1, followed Basic washing - 2, followed by forming an azeotrope mixture of a non-solvent with intrinsic impurities - 3

[00191] In a sixth aspect shown on figure 6, the process for treating the input waste material 10 comprises acid washing the input waste material 10 with an acidic solution 70, thereby obtaining the acid washed output waste material 110. The acid washing can be done as described in the first aspect. The process further comprises subsequent basic washing the acid washed output waste material 110 with a basic solution 80, thereby obtaining the acid basic washed output waste material 220. The basic washing can be done as described in the second aspect.

[00192] The acid basic washed output waste material 220 is then mixed S350 with a nonsolvent 90 in the liquid state in the apparatus 100 for forming an azeotrope mixture of the non-solvent 90 with intrinsic impurities 15. The mixing 350 is followed by outputting S370 at least part of intrinsic impurities 15 in a gaseous state from the apparatus 100, thereby obtaining S400 an acid basic washed mixed output waste material 320.

[00193] In one example, the acid basic washed mixed output waste material 320 has a reduced content of intrinsic impurities relative to the initial content of intrinsic impurities.

[00194] In one example, the sixth aspect results in an improved removal of intrinsic impurities 15 in the acid basic washed mixed output waste material 320 from the input waste material 10.

[00195] The acid washing SI 00, followed by the basic washing S200, followed by the mixing S350 of the acid basic washed output waste material 220 with the non-solvent 90 in the liquid state in the apparatus 100 for forming the azeotrope mixture of the non-solvent 90 with the intrinsic impurities 15 enables to obtain an improved acid basic washed mixed output waste material 320. The acid basic washed mixed output waste material 320 is an improved quality recycled polymer.

Basic washing - 2, followed by Acid washing - 1, followed by forming an azeotrope mixture of a non-solvent with intrinsic impurities - 3

[00196] In a seventh aspect shown on Fig. 7, the process for treating the input waste material 10 comprises the features of the third aspect and further comprises mixing S350 the basic acid washed output waste material 225 from the fourth aspect with the non-solvent 90 in the liquid state in the apparatus 100, thereby obtaining a basic acid washed mixed output waste material 325.

[00197] In one example, the basic acid washed mixed output waste material 325 has a reduced content of intrinsic impurities relative to the initial content of intrinsic impurities.

[00198] The basic washing S200, followed by the acid washing SI 00, followed by the mixing S350 of the output waste material 225 with the non-solvent 90 in the liquid state in the apparatus 100 for forming the azeotrope mixture of the non-solvent 90 with the intrinsic impurities 15 enables to obtain an improved basic acid washed mixed output waste material 325. The basic acid washed mixed output waste material 325 is an improved quality recycled polymer. Basic washing - 2, followed by forming an azeotrope mixture of a non-solvent with intrinsic impurities - 3

[00199] In an eighth aspect shown on Fig. 8, the process for removing intrinsic impurities 15 from the input waste material 10 comprises mixing S350 the basic washed output waste material 210 from the second aspect with the non-solvent 90 in the liquid state in the apparatus 100, thereby obtaining a basic washed mixed output waste material 330.

[00200] In one example, the basic washed mixed output waste material 330 has a reduced content of intrinsic impurities relative to the initial content of intrinsic impurities.

[00201] The basic washing S200, followed by the mixing S350 of the basic washed output waste material 210 with the non-solvent 90 in the liquid state in the apparatus 100 for forming the azeotrope mixture of the non-solvent 90 with the intrinsic impurities 15 enables to obtain an improved basic washed mixed output waste material 330. The basic washed mixed output waste material 330 is an improved quality recycled polymer.

Pre-treatment

[00202] It is possible that the process for removing intrinsic impurities from the input waste material further comprise pre-treating the input material. Such a process with a pre-treatment step is illustrated on Fig. 9, with the acid washing of Fig. 1. The pre-treatment is not a compulsory step of the acid washing. In addition, even though the pre-treatment is not illustrated in the other aspects, the input material may be pre- treated in one or more of the aspects shown in the figures.

[00203] The pre-treating S50 comprises, in one example, a first reducing of the size of the input waste material 10, preferably cutting the input waste material 10 and/or shredding the input waste material 10, more preferably cutting the input waste material and shredding the input waste material 10, preferably shredding the input waste material 10 to 50 mm.

[00204] The pre-treating S50 further comprises, in one example, at least one step of removing extrinsic impurities from the input waste material 10, such as removing rough waste, i.e., iron (Fe) particles, contaminants such as stones or glass, paper fibers, including (incl.) moisture, or a combination thereof. In one example, the removing of the paper fibers is a two-step removing of the paper fibers for removing the paper fraction. [00205] The pre-treating S50 comprises, in a further example, a second reducing of the size of the input waste material 10, preferably cutting the input waste material 10, more preferably cutting the input waste material 10 to 20 mm.

Optional Treatment Steps

[00206] In one example, the input waste material 10 further comprises foreign plastics, such as polyethylene terephthalate (PET), polypropylene (PP), polyamide (PA) as thicker nonpolyethylene foils, non-foil plastics, such as caps, or a combination thereof.

[00207] In a further example, the recycling process comprises removing the foreign plastics and the non-foil plastics.

[00208] In one example, the removing of the foreign plastics and the non-foil plastics are conducted by air sorting in subsequent air separators or in air separators mounted in parallel. [00209] In another example, the recycling process comprises a wet density sorting step to split the input waste material 10 in a light fraction, i.e., mainly polyolefins, and a heavy fraction, i.e., heavy plastics and other materials with a density > 1 g/cm³).

[00210] In one further example/ aspect, the density sorting step is followed by sorting out at least one output light non-foil element in a wind-sifter. The sorting device is, for example, an air separator, such as wind-sifter. The principle of wind-sifters is general knowledge. An input material is fed into a separation chamber of the wind-sifter. An air flow is generated in the separation chamber. Particles from the input material with higher sink speed than the counter air flow, such as aluminium or non-foil elements, are discharged as heavies. Remaining particles from the input material with lower sink speed than the counter air flow, such as foils, are dragged with the air flow. The discharged, i.e., output fractions are listed as non-limiting examples, depending on the counter air flow speed the cut-off between heavies, i.e., heavy fraction, and the lights, i.e., light fraction, that may be different. An example of wind-sifter is a zig-zag sifter. It is known that a zig zag sifter enables modulating a linear direction and a circular direction of the air flow. The modulating enables preventing particles from being discharged as heavies instead of dragged with the air flow erroneously. [00211] The position of the optional treatment steps, wet density sorting and air sorting, in the overall recycling process is variable and can be arranged by the skilled person in various positions. For instance, the air sorting can be positioned before the at least one washing process steps to reduce the input amount for the washing process. But it can be positioned also after the at least one washing process steps so that this material fraction is also washed to achieve a higher quality.

[00212] Examples

[00213] The input waste material of Example 1 to 12 were pretreated. The pre-treatment process is disclosed in the following.

Pretreatment

[00214] The input waste material 10 was made of a bale of paper mill reject (810 kg of Poly Al) from a central European paper mill and was recycled. The input waste material 10 made of the bale had a moisture content of 30 % and a dry mass of 567 kg. The input waste material 10 was cut in a guillotine to open up the bale wire of the input waste material 10 and was shredded to 50 mm. 18 kg of rough waste like stones, glass as well as ferric metals were removed in a rough waste removal device, i.e., a magnetic separator and/or a heavy material trap. The fibre content of the input waste material 10 was between 10 % by weight and 30 % by weight. A further coarse defibering was performed in a paper layer removal device in which 347 kg of fiber materials of the paper layer were removed. The particle size of the defibered material was further reduced to 20 mm by a second shredder.

Acid washing - 1

Example 1 :

[00215] In Example 1, 20 g flakes of the input waste material 10 after pre-treatment was treated, i.e., acid washed S100, in a beaker with 1 L of an acidic solution 70.

[00216] The acidic solution 70 was a formic acid water solution comprising up to 60 w-% of formic acid.

[00217] The at least one acid washing SI 00 was conducted at a temperature of 70 °C and for 4 hours.

[00218] The at least one acid washing SI 00 was followed by removing SI 50 the acidic solution 70 comprising at least part of the impurities 15, i.e., separating the at least one polymer fraction from the acidic solution 70 with a sieve, thereby obtaining S400 an acid washed output waste material 110. [00219] The acid washed output waste material 110 was washed on the sieve with a washing fluid comprising deionized water to neutralize the pH value of the acidic solution 70.

[00220] The collected acidic solution 70 and washing fluid, comprised a content of aluminium particles and paper fibers originating from the used beverage carton waste input material 10, respectively.

[00221] The acid washed output waste material 110 was further dried.

Example 2:

[00222] In Example 2, the same experimental conditions than for Example 1 were conducted, except that the acidic solution 70 was an acetic acid water solution 70 comprising up to 60 w-% of acetic acid.

Basic washing - 2

Example 3 :

[00223] In Example 3, 100 g flakes of the input waste material 10 after pre-treatment was treated, i.e., basic washed S200, in a beaker with 4 L of a basic solution 80.

[00224] The basic solution 80 was a sodium hydroxide water solution with at least 5% w- of sodium hydroxide. Different values of content of sodium hydroxide were tried and will be presented below.

[00225] The at least one basic washing S200 was conducted at several temperatures listed in Table 5, i.e. room temperature (RT), 40 °C, 50 °C, 60 °C and 70 °C and different duration, i.e., 30 min, 45 min and 1 hour.

[00226] During the basic washing S200, a greenish solid occurred as voluminous solid material and was located in the basic solution 80.

[00227] The at least one basic washing S200 was followed by removing S250 the basic solution 80 comprising at least part of the impurities 15, i.e., separating the at least one polymer fraction from the basic solution 80 comprising the greenish solid, with a sieve, thereby obtaining S400 a basic washed output waste material 210.

[00228] The basic washed output waste material 210 was washed on the sieve with a washing fluid comprising deionized water to neutralize the pH value of the alkaline basic solution 80 and to wash out the green solid. [00229] The collected basic solution 80 and washing fluid comprised a content of aluminium particles and paper fibers originating from the input waste material 10 made of UBC, respectively. The content of aluminium particles originated, for example, from the input waste material 10 comprising a content of aluminium substantially low and so the aluminium was completely dissolved by oxidative corrosion during the basic washing S200. [00230] The basic washed output waste material 210 was further dried.

[00231] A summary of the experimental conditions of the Example 3 are provided below in Table 2 and Table 3 below. Table 2:

Table 3:

[00232] The input waste material 10 in Tables 2 and 3 came from two central European paper mills (I and II). The input waste materials 10 represented seasonal fluctuations of used beverage carton (UBC) material. In other words, the input waste material 10 were the same UBC but measured at different times of the year.

[00233] Intrinsic impurities 15 had a melting point measured on a hot stage microscope of 205 °C with a remaining solid which is not melting up to 300 °C

As a comparison, the melting points of calcium stearate (Ca stearate) is 155 °C and from sodium stearate (Na stearate) is 205 °C. An Ash content of intrinsic impurities 15 comprises 15% of sodium oxide (Na2O).

[00234] Intrinsic impurities 15 comprised Na stearate causing a white color. [00235] Intrinsic impurities 15 further comprised organic compounds: pigments and varnish of UBC, causing greenish/brownish color.

[00236] Intrinsic impurities 15 further comprised minor contents of remaining fibers that are hard to fully remove.

Acid washing - 1, followed by Basic washing - 2

Example 4:

[00237] In Example 4, 20 g flakes of the input waste material 10 after pre-treatment was treated, i.e., acid washed S100 in a beaker with 1 L of an acidic solution 70.

[00238] The acidic solution 70 was a formic acid water solution comprising up to 30 w-% of formic acid.

[00239] The at least one acid washing S100 was conducted at a temperature of 70 °C and for 4 hours.

[00240] The at least one acid washing SI 00 was followed by removing SI 50 the acidic solution 70 comprising at least part of the impurities 15, i.e., separating the at least one polymer fraction from the acidic solution 70 with a sieve, thereby obtaining S400 an acid washed output waste material 110.

[00241] The acid washed output waste material 110 was washed on the sieve with a washing fluid comprising deionized water to neutralize the pH value of the acidic solution 70, i.e., to reach a PH value of at least 4.

[00242] The collected acidic solution 70 and washing fluid, comprised a content of aluminium particles and paper fibers originating from the input waste material 10 made of UBC, respectively.

[00243] The acid washed output waste material 110 was wet.

[00244] The acid washed output waste material 110 was then treated, i.e., basic washed S200, in a beaker with 1 L of a basic solution 80.

[00245] The basic solution 80 was a sodium hydroxide water solution with at least 5% w- of sodium hydroxide.

[00246] The basic washing S200 was conducted at 70°C for one hour.

[00247] During the basic washing S200 a greenish solid occurred as voluminous solid material and was located in the basic solution 80. [00248] The at least one basic washing S200 was followed by removing S250 the basic solution 80 comprising at least part of the impurities 15, i.e., separating the at least one polymer fraction from the acidic solution 80 comprising the greenish solid, with a sieve, thereby obtaining S400 an acid basic washed output waste material 220.

[00249] The acid basic washed output waste material 220 was washed on the sieve with a washing fluid comprising deionized water to neutralize the pH value of the alkaline, i.e., basic solution 80 to reach a pH value of at least 9 and to wash out the green solid.

[00250] The collected basic solution 80 and washing fluid comprised a content of aluminium particles and paper fibers originating from the input waste material 10 made of UBC and not removed by the acid washing SI 00, respectively. The content of aluminium particles originated, for example, from the input waste material 10 comprising a content of aluminium substantially low and so the aluminium was completely dissolved by oxidative corrosion during the basic washing S200.

[00251] The acid basic washed output waste material 220 was further dried.

Example 5:

[00252] In Example 5, the same experimental conditions than for Example 4 were conducted, except that the acidic solution 70 was an acetic acid water solution 70 comprising up to 60 w-% of acetic acid.

Acid washing - 1, followed by forming an azeotrope mixture of a non-solvent with intrinsic impurities - 3 / Basic washing - 2, followed by forming an azeotrope mixture of a nonsolvent with intrinsic impurities - 3 / Acid washing - 1, followed by Basic washing - 2, followed by forming an azeotrope mixture of a non-solvent with intrinsic impurities - 3

Examples 6, 7, 8, 9 and 10:

[00253] The acid washed output waste materials 110 of Examples 1 and 2, the basic washed output waste materials 210 of Example 3, and the acid basic washed output waste materials 220 of Examples 4 and 5 had a shape of colored and uncolored flakes with an irregular geometry, and a thickness below 100 pm.

[00254] The content of intrinsic impurities 15 was 1.2% before the extrusion. [00255] In Examples 6, 7, 8, 9 and 10, the acid washed output waste material 110 (two acidic solutions 70), the basic washed output waste material 210, and the acid basic washed output waste material 220 (two acidic solutions 70) from Examples 1, 2, 3, 4, 5, respectively, were mixed with a non-solvent 90 comprising water for forming an azeotropic mixture with intrinsic impurities 15.

[00256] The pressure in the injector 160 was 76 bar.

[00257] The content of intrinsic impurities 15 in the acid washed mixed output waste material 310 of Example 6 was < 0.05 %.

[00258] A process cascade is improving the removing, i.e., the removal, of the content of intrinsic impurities, to each very low content of intrinsic impurities necessary for food applications.

Quantification of decontamination efficiency for Examples 1 to 10:

[00259] Table 4 below gives a summary of the decontamination efficiency by means of odor, color, total VOC amount (VOCtotai) and VOC corresponding to hydrocarbons (VOC hydrocarbons). The comparison is done with a reference material. The reference material is the material of the example which is the input waste material 10 plasticized by means of a typical industrial extrusion process to produce granulates at a temperature of 190 °C, i.e., below 200°C, with a degassing unit and a melt filtration device of 100 pm. In the reference material, no acid washing, no basic washing and no step of mixing the forming an azeotrope mixture of a non-solvent with intrinsic impurities had been performed.

[00260] For the odor comparison, the odor was characterized by an olfactory perception of a test person. The test person is a skilled lab technician working in the area of polymer processing. The test person could hereby choose between: 0 = no exceptional odor (typical for virgin polymer material (like LDPE), 1 = slight exceptional odor (recognized as nonvirgin material but the odor is so low that a substitution of the virgin polymer material by recyclate is acceptable by odor means), 2 = medium exceptional odor (substitution of a virgin polymer material can still be done but only for non-odor sensitive application fields like waste bags) and 3 = intensive exceptional odor (substitution of virgin polymer material by the recyclate is excluded due to the intensive odor). The odor is often described as fishy, spoiled meat or typical amine compound odor. [00261] For the color comparison, the color and transparency improvement of a plasticized sample was analyzed by a Colorimeter. Therefore, a plasticized sample sheet with a wall thickness of 0.4 mm is prepared. The sample is measured against a white and a black background with a Colorimeter. The difference in the determined L values (CIELAB color space, D65) for the white and the black background was measured, and a pleasing decontamination efficiency was stated then the AL value was >30 after the decontamination step. AL is defined hereby as: AL = measured L value against a white background with the material sample above the background - measured L value against a black background with the material sample above the background. A AL of 100 is found for a perfect transparent foil because the L value against the white background is -100 and the L value against the black background is -0. A AL of 0 is typically found for a non-transparent sample so that the background cannot be observed due to the non-transparency of the sample.

[00262] For the total VOC amount (VOC total) and VOC corresponding to hydrocarbons (VOC hydrocarbons), a migration experiment followed by a gas chromatography, mass spectrometer (GC-MS) analysis was performed. 2,5 g of each sample listed in Table 4 below was brought into contact with 5 mL of 95% ethanol (migration simulant). The migration experiments were carried out for 10 days at 60°C. The measurements were performed in duplicate. Before the GC-MS screening measurement, an additional internal standard was added for semiquantitative evaluation (Naphthalene-D8). Aliquots of the 95% ethanol migration solutions were analyzed via GC-MS using a non-polar capillary column. Identification of substances was done by use of spectral libraries (NIST/Wiley) and manual spectra interpretation as internal standard.

Table 4:

Example 11 :

[00263] The inventors showed the impact of the content of the NaOH in the basic solution, coupled with the temperatures applied during the basic washing. Several temperatures and different content of NaOH are provide in the Table 5 below.

Table 5:

[00264] The colour code of Table 5 shows the decontamination efficiency that is assessed by the greenish colour of the removed solution after treatment. A greenish color of the solution means that the solution comprises intrinsic impurities, and so intrinsic impurities were removed from the input waste material. Dark grey means no greenish color and thus insufficient decontamination. Medium dark grey corresponds to a beginning of a slight greenish coloration of the treatment solution. Light grey corresponds to a light greenish coloration of the treatment solution. White colour corresponds to a significant greenish coloration of the treatment solution.

[00265] As can be seen on Table 6 below, the best combination found based on Table 5 by the inventors to remove intrinsic impurities 15 is:

Table 6:

[00266] The inventors showed that the increase in sodium hydroxide content does not lead to an improvement of the input waste material treatment, as should be expected.

[00267] The inventors surprisingly showed that the improvement of the input waste material treatment results from the combination of high temperature and a high content of NaOH. [00268] The inventors showed the surprising effect of combining high temperature with a high content of sodium hydroxide.

[00269] Further, the inventors showed that at a low content of NaOH, i.e., 3 wt. % of NaOH, at 60°C, does not enable to remove intrinsic impurities 15, so it was not obvious to increase the content of NaOH to 6 wt.% of NaOH because already 3 wt% of NaOH is already highly alkaline and the increased capacity to remove more reliably intrinsic impurities could not have been expected and is most surprising.

[00270] Further, highly alkaline conditions are obtained with a low content of NaOH. A basic solution 80 comprising 1 w-% sodium hydroxide solution has a pH value of 13.4. A basic solution 80 comprising 3.9 w-% sodium hydroxide solution (1 M) has a pH value of 14 which is the limit of the pH value scale. The significant differences in the decontamination efficiency observed in Example 11 are surprising for a marginal increase of the pH value.

Reference Numerals

10 input waste material

15 intrinsic impurities

20 extrinsic impurities

70 acidic solution

80 basic solution

90 non-solvent

100 apparatus

120 hopper

160 injector

170 mixing element

180 heating element

190 output element

195 material outlet

110 acid washed output waste material

210 basic washed output waste material

220 acid basic washed output waste material

225 basic acid washed output waste material

310 acid washed mixed output waste material

320 acid basic washed mixed output waste material

325 basic acid washed mixed output waste material

330 basic washed mixed output waste material

SI 00 acid washing

S200 basic washing

S310 melting

S320 injecting

S350 mixing

S370 outputting

S400 obtaining

Claims

1. Process for treating an input waste material (10) comprising at least one polymer fraction, the input waste material (10) having an initial content of intrinsic impurities (15) located in the at least one polymer fraction, preferably the intrinsic impurities comprised intentionally added substances (IAS) and non-intentionally added substances (NIAS), more preferably the intrinsic impurities are comprised of one of organic compounds, such as organic volatile compounds (VOC), and/or inorganic compounds, more preferably the intrinsic impurities are comprised of one of monomers, oligomers, phosphates, phenols, ink particles, pigments particles, metal ions, titanium dioxide (TiCh), iron oxide, zinc oxide, sodium stearate, calcium stearate, varnish particles, organic solvents, or a combination thereof, wherein the process comprises: a) acid washing (S100) the input waste material (10) with an acidic solution (70), preferably the acidic solution (70) comprises a carboxylic acid, more preferably the carboxylic acid is selected from one of methanoic acid or ethanoic acid; followed by removing (SI 50) the acidic solution (70) comprising at least part of intrinsic impurities (15); thereby obtaining (S400) an acid washed output waste material (110); and c) mixing (S350) a non-solvent (90) in a liquid state with the acid washed output waste material (110) in an apparatus (100) for forming an azeotrope mixture of the non-solvent (90) with intrinsic impurities (15); followed by outputting (S370) at least part of intrinsic impurities (15) in a gaseous state from the apparatus (100); thereby obtaining (S400) an acid washed mixed output waste material (310).

2. The process of claim 1, further comprising: b) basic washing (S200) the acid washed output waste material (110) with a basic solution (80) after a) the acid washing (SI 00), preferably the basic solution (80) comprises sodium hydroxide, more preferably at least 6 wt.% of sodium hydroxide respective to the basic solution (80), most preferably at least 8 wt.% respective to the basic solution (80); followed by removing (S250) the basic solution (80) comprising at least part of intrinsic impurities (15); thereby obtaining (S400) an acid basic washed output waste material (220); c) followed by the mixing (S350); thereby obtaining (S400) an acid basic washed mixed output waste material (320).

3. The process of claim 2, wherein b) the basic washing (S200) is conducted prior to a) the acid washing (SI 00); thereby obtaining (S400) a basic acid washed output waste material (225); followed by c) the mixing (S350); thereby obtaining (S400) a basic acid washed mixed output waste material (325).

4. Process for treating an input waste material (10) comprising at least one polymer fraction, the input waste material (10) having an initial content of intrinsic impurities (15) located in the at least one polymer fraction, preferably the intrinsic impurities comprised intentionally added substances (IAS) and non-intentionally added substances (NIAS), more preferably the intrinsic impurities are comprised of one of organic compounds, such as organic volatile compounds (VOC), and/or inorganic compounds, more preferably the intrinsic impurities are comprised of one of monomers, oligomers, phosphates, phenols, ink particles, pigments particles, metal ions, titanium dioxide (TiCh), iron oxide, zinc oxide, sodium stearate, calcium stearate, varnish particles, organic solvents, or a combination thereof; wherein the process comprises at least: b) basic washing (S200) the input waste material (10) with a basic solution (80), preferably the basic solution (80) comprises sodium hydroxide, more preferably at least 6 wt%. of sodium hydroxide, most preferably at least 8 wt.%, respective to the basic solution (80), followed by removing (S250) the basic solution (80) comprising at least part of the intrinsic impurities (15), thereby obtaining (S400) a basic washed output waste material (210); and c) mixing (S350) a non-solvent (90) in a liquid state with the basic washed output waste material (210) in an apparatus (100) for forming an azeotrope mixture of the non-solvent (90) with intrinsic impurities (15), followed by outputting (S370) at least part of intrinsic impurities (15) in a gaseous state from the apparatus (100), thereby obtaining (S400) a basic washed mixed output waste material (330).

5. The process of any one of the above claims, wherein the at least one polymer fraction comprises polyethylene (PE), more preferably low- density polyethylene (LDPE), and/or the input waste material (10) comprises at least one paper fraction, and/or the input waste material (10) comprises at least one metal fraction, preferably the at least one metal fraction comprises aluminium.

6. The process of any one of the above claims, wherein the input waste material (10) is one of a post-consumer waste, a recycled polymer, or a used beverage carton (UBC).

7. The process of any one of claims 1 to 3, 5 or 6 when dependent on any one of claims 1 to 3, wherein a) the acid washing (SI 00) is conducted: at a temperature of at least 50°C, preferably at a temperature between 60°C and 100°C, more preferably at 70°C; and/or for at least 120 min, preferably for 240 minutes.

8. The process of any one of claims 2 to 7, wherein b) the basic washing (S200) is conducted: at a temperature of at least 50°C, preferably at a temperature between 60°C and 70°C; more preferably at 70°C, and/or for at least 30 minutes, preferably for between 30 minutes and 140 minutes, more preferably between 60 min and 140 minutes.

9. The process of any one of the above claims, wherein the non-solvent (90) comprises at least one of water, a base, preferably the base is selected from one of ammonia or pyridine; an alcohol, preferably the alcohol is selected from one of methanol, ethanol, or isopropanol; carbon dioxide; preferably carbon dioxide and water, more preferably the carbon dioxide is at a content between 10% and 50% by weight respective to the water; or a combination thereof.

10. The process of any one of the above claims, further comprising a density sorting step to obtain a light fraction and a heavy fraction, the light fraction has a density of less than 1 g/cm³, and the heavy fraction has a density of higher than 1 g/cm³, preferably the density sorting step is followed by sorting out at least one output light non-foil element in a wind-sifter.

11. The process of any one of the above claims, wherein c) the mixing (S350) with the non-solvent (90) in the liquid state is conducted in the apparatus (100) at: a temperature between 110 °C and 330 °C; and/or a pressure between 10 and 300 bar; and/or a water content below 5 % respective to the mass of an input material added into the apparatus (100).

12. The process of claim 11, wherein the apparatus (100) is an extruder, configured for extruding plastic material.

13. The process of any one of the above claims for treating the input waste material (10) having a higher initial content of extrinsic impurities (20) as compared to output waste material, preferably the extrinsic impurities (20) are selected from one of ink particles, pigments particles, varnish particles, or a combination thereof.

14. Material obtained by a process according to any of the preceding claims, in particular one of an acid washed mixed output waste material (310), an acid basic washed mixed output waste material (320), basic acid washed mixed output waste material (325), and a basic washed mixed output waste material (330), made of recycled polymer comprising at least one polymer fraction, preferably made of PE, having a residual content of intrinsic impurities (15) of intentionally added substances (IAS), such as tris(2,4-di-tert-butylphenyl) phosphite, of below 10 ppm, preferably below 3 ppm; and a residual content of non-intentionally added substances (NIAS) selected from oligomers, such as hexadecanoic acid, preferably hexadecanoic acid, below 200 ppm.

15. Use of the material of claim 14, in particular of one of an acid washed mixed output waste material (310), an acid basic washed mixed output waste material (320), basic acid washed mixed output waste material (325), and a basic washed mixed output waste material (330), in a consumer package, preferably for food applications.