WO2025012254A2

WO2025012254A2 - Process for the pre-treatment of textile waste

Info

Publication number: WO2025012254A2
Application number: PCT/EP2024/069313
Authority: WO
Inventors: Madiha DALIBEY
Original assignee: Carbios SA
Current assignee: Carbios SA
Priority date: 2023-07-10
Filing date: 2024-07-09
Publication date: 2025-01-16
Anticipated expiration: 2026-01-10
Also published as: TW202509131A; WO2025012254A3

Abstract

The invention relates to a process for the pre-treatment of textile waste comprising at least one polymer; comprising a shredding step, different separating steps, and a recovering step. It further relates to a process for recycling textile waste comprising at least one polymer, comprising implementing the pre-treatment process according to the invention and at least one further step, preferably a further extrusion and/or depolymerization step.

Description

PROCESS FOR THE PRE-TREATMENT OF TEXTILE WASTE

TECHNICAL FIELD

The invention relates to a process for the treatment of textile waste. The process of the invention aims among others at transforming textile waste, such as polymeric textile waste, into a material that is optimized for its further downstream treatment by conventional techniques for its recycling.

TECHNICAL BACKGROUND

In the textile industry, finished apparel and related goods have a limited lifespan. When they have ended their useful life, they typically end up in a landfill or waste incineration facility. Thousands of tons of used textile waste are generated each year. Regenerated fibers have become increasingly popular as a sustainable alternative to virgin fibers.

In general, textiles for recycling are generated from two primary sources, including: (1) preconsumer sources, such as scrap created as a by-product from yam and fabric manufacture; (2) post-consumer sources, such as discarded garments, vehicle upholstery, household textiles (sheets, towels, and pillowcases) and others.

For synthetic-based textiles (polyester, nylon), garments are shredded and then granulated and processed into synthetic chips. The chips are subsequently melted and used to create new fibers for use in the synthetic fabrics. However, contaminants, such as metals, buttons, zippers and others are present in a large amount in textiles waste and typically present problems with recycling processes. In an amount above 5%, contaminants may for instance hinder extrusion and affect the properties of the resulting fiber.

Many approaches have been developed for textile recycling. Mechanical recycling technology remains the most-used technology which involves the direct reuse of uncontaminated discarded polymer into a new product. However, in this case, complications may arise, such as necessity of selective collection and rough (manual) sorting. This method is unpopular among recyclers because it significantly increases the costs of recyclates.

An alternative approach is the use of solvent-based processes to separate and recover components (e.g. cotton and PET) since a solvent can dissolve either cellulose or PET. As a result, conventional methods of recycling and/or regenerating synthetic textiles are associated with significant drawbacks, such as the use of expensive and harsh chemical solvents, complex recycling methods, waste water discharge, pollution, energy use that renders the process cumbersome, and significant expenditures of time. It would therefore be beneficial to overcome the shortcomings of current technology by providing a simple and cost-effective method of regenerating premium synthetic recycled fibers that significantly reduces chemical usage and waste water production.

Thus, there remains a need to provide new processes for the pre-treatment of polymer textile waste, said processes affording pre-treated textile waste that is suitable for downstream recycling by various methods, including methods involving an extrusion step, and overcoming the above-described drawbacks.

SUMMARY OF THE INVENTION

In this respect, the inventors have evidenced that the implementation of a specific series of pretreatment steps on polymeric textile waste affords pre-treated textile waste whose physicochemical properties are suitable for the further implementation of various downstream recycling methods. Especially, the pre-treatment process according to the invention provides the pretreated textile waste with physico-chemical properties suitable for a further depolymerization step, and/or a further extrusion step. The yield of the further downstream recycling steps, such as depolymerization and/or extrusion steps, is optimized thanks to the implementation of the pre-treatment process according to the invention.

Thus, the present invention relates to a process for the pre-treatment of textile waste comprising at least one target polymer to obtain pre-treated textile waste suitable to be submitted to an extrusion step, comprising the following steps: a) providing textile waste comprising at least one target polymer, b) shredding the textile waste provided at step a) to obtain shreds, wherein the shreds comprise shreds comprising metallic parts and/or shreds not comprising metallic parts, c) separating at least part of the shreds comprising metallic parts from the shreds not comprising metallic parts by submitting at least part of the shreds obtained at step b) to a magnetic field and/or an Eddy current, d) submitting the shreds not comprising metallic parts separated at step c) to an air stream, to obtain a lighter fraction and a heavier fraction, e) recovering the lighter fraction obtained at step d), said lighter fraction comprising pretreated textile waste, and f) optionally packaging the pre-treated textile waste. The present invention also relates to a process for recycling textile waste comprising at least one target polymer, comprising implementing the pre-treatment process according to the invention, and implementing at least one further step being an extrusion step, such as an extrusion-foaming step, and/or a depolymerization step, such as a hydrolysis step, preferably an alkaline hydrolysis step.

In some embodiments, the at least one target polymer is a thermoplastic polymer, preferably selected from the group consisting of polyesters, polyamides and mixtures and/or blends thereof, more preferably polyesters, in particular PET.

In some embodiments, the textile waste further comprises at least one further polymer other than the target polymer. The at least one further polymer is preferably selected from the group consisting of cellulose, polyesters, polyamides, poly acrylates, polypropylene, polyetherpolyurea copolymers, polyurethanes, lignocellulosic polymers, polysiloxanes, natural polymeric fibers, polyetheretherketones (PEEK), polyamide-imides (PAI), polyimides (PI), polyphenylene sulfides (PPS), polyphenyl sulfones (PPSU), polysulfones (PSU), polyethersulfones (PES), polyetherimides (PEI), and combinations thereof.

In some embodiments, the pre-treatment process comprises, before shredding step b), a preliminary step a’) selected from the group consisting of a sorting step, a coarse pre-shedding step, an opening step, a chemolysis step, a solvolysis step, a dissolution step, a washing step, a disinfecting step, a sterilizing step, a biologically cleaning step and any combination thereof.

In some embodiments, the pre-treated textile waste is further submitted, after recovering step e), to one or more steps selected from the group consisting of a compaction step, a densification step, a pelletizing step, an extrusion step, preferably an extrusion-foaming step, a pyrolysis step, a gasification step, a depolymerization step, a chemolysis step, a solvolysis step and a dissolution step.

In some embodiments, the pre-treated textile waste is submitted, after recovering step e), to an extrusion step, preferably an extrusion-foaming step, more preferably performed in an extruder, optionally followed by a depolymerization step.

In some embodiments, the extrusion step, preferably the extrusion-foaming step, is performed at a temperature at which at least one target polymer comprised in the pre-treated textile waste is in a partially or totally molten state. In some embodiments, the extrusion step is an extrusion-foaming performed at a temperature at which at least one polymer comprised in the pre-treated textile waste is in a partially or totally molten state.

In some embodiments, the extrusion step is implemented with a physical foaming agent, preferably selected from gas, more preferably selected from the group consisting of nitrogen, carbon dioxide, methane, helium, neon, argon, xenon, hydrogen and any mixture thereof, or with a chemical foaming agent, preferably selected from the group consisting of citric acid, carbonate and any mixture thereof.

In some embodiments, the extrusion step is followed by a cooling step. In some embodiments, the extrusion step is an extrusion-foaming step followed by a cooling step. In some embodiments, the cooling step is performed at a temperature below 100°C, preferably below 90°C.

In some embodiments, the process for recycling textile waste according to the invention comprises: i) submitting textile waste comprising at least one target polymer to a pre-treatment process according to the invention to obtain pre-treated textile waste suitable to be submitted to an extrusion step, ii) contacting the pre-treated textile waste obtained at step i) with a depolymerizing agent, in conditions suitable for depolymerizing said at least one target polymer, to obtain a mixture comprising oligomers and/or monomers of said at least one target polymer, and iii) recovering and optionally purifying the oligomers and/or monomers obtained at step ii).

In some embodiments, the depolymerizing agent is selected from chemical and biological depolymerizing agents. Preferably, the depolymerizing agent is an enzyme, more preferably the depolymerizing agent is an enzyme able to degrade said at least one target polymer comprised in the pre-treated textile waste obtained at step i).

In some embodiments, the depolymerizing agent is a biological depolymerizing agent which is a depolymerase, preferably a depolymerase selected from the group consisting of a cutinase, a lipase, a protease, a carboxylesterase and an esterase, more preferably a cutinase, and at least two different depolymerizing agents are preferably used at step ii).

In some embodiments, the process according to the invention comprises: i) submitting textile waste comprising at least one target polymer to a pre-treatment process according to the invention to obtain pre-treated textile waste suitable to be submitted to an extrusion step, ii) submitting the pre-treated textile waste obtained at step i) to an extrusion step, preferably an extrusion-foaming step, to obtain an extruded pre-treated textile waste, iii) contacting the extruded pre-treated textile waste obtained at step ii) with a depolymerizing agent, in conditions suitable for depolymerizing said at least one target polymer, to obtain a mixture comprising oligomers and/or monomers of said at least one target polymer, and iv) recovering and optionally purifying the oligomers and/or monomers obtained at step iii).

In some embodiments, the at least one target polymer comprised in the textile waste is polyethylene terephthalate (PET), and the depolymerizing agent is an enzyme able to degrade polyethylene terephthalate (PET).

DETAILED DESCRIPTION OF THE INVENTION

Definitions

The present disclosure will be best understood by reference to the following definitions.

According to the present invention, “textile" is broadly used herein, and includes fibers, filaments, yarns, woven and non-woven fabrics, knits, and finished products (such as garments).

By “ Textile articles’" (or finished products), it is meant any textile categories, like clothes such as shirts, jeans, skirts, dresses, suits, coveralls, pants, underwear, sweaters, and the like; used home textiles such as bed linen, towels, curtains, cloths, tablecloths, carpet, rug, seat covers, upholstery fabrics, or the like; furnishing; shoes. The textile article may comprise mono- or multilayer parts of textile materials as well as other components that are not textile (such as zippers, buttons, etc).

“Textile waste” according to the invention refers to mainly mixed textiles waste comprising at least one polymer component. By “mixed textiles articles”, it is meant a mixture of different types and/or categories of textile articles commonly known in the art, such as clothes, home textiles, shoes, etc. Textile waste treated or pre-treated according to the invention may also be provided with some non-textile waste, mixed with the textile waste. The textile waste may originate from various sources such as used garments, cloths, technical textile fibers such as fibers used in tires or in straps, excess from textile factories, etc. The textile waste to be treated or pre-treated according to the invention comprises polymer material or blended textile such as cellulose/polymer blend material, preferably cotton/polyester blend material (also known as polycotton) and/or polyamide/polyester blend material. The term “blended” may refer to a textile article comprising different types of materials or polymers which may be interwoven, knitted, or otherwise fixed (e.g., stitched or glued) together to form a mixed material textile and/or to textiles that combine the different types of materials (e.g., PET, elastane, dyes, polyurethane, acrylic, etc.) into the fibers from which a particular textile is made (e.g., knitted or woven). The textile waste can be blended textile waste which is pre-consumer and/or postconsumer textile waste.

The textile waste may be in the form of mixed, unsorted pre-consumer, postconsumer and postindustrial textiles.

“Pure textile material” refers to textile material included in the textile article or in the textile waste, and comprising only textile fibers to the exclusion of any non-textile impurities (such as zippers, buttons, etc).

“Post-consumer textile waste ” refers to textiles that had already arrived at the end consumer and may contain foreign substances (such as zippers, buttons, clothing accessories, ...). Postconsumer textile waste can comprise one or several textile articles.

“Pre-consumer textile waste ” refers to textile materials that had not yet arrived at the end consumer, but resulted as waste in the course of production processes. This may include cutting residues or wastes from the production of clothing, home textiles, nonwovens, or wastes from the production of fibers, yams or finished textile products. The “Pre-consumer textile waste ” may also include unsold finished textile products.

In some embodiments, the textile waste comprising at least one polymer further comprises a natural fiber-containing material and/or additional synthetic fiber-containing material. Examples of natural fiber-containing material include, but are not limited to, woven fabric, nonwoven fabric, fibers, yarns, threads, and the like.

A “polymer” refers to a chemical compound or mixture of compounds whose structure is constituted of multiple repeating units (i.e. “monomers” linked by covalent chemical bonds. Within the context of the invention, the term “polymer” refers to such chemical compound used in the composition of a textile waste. Examples of polymers include, but are not limited to, polyesters, polyamides including nylons, polyamines, polycarbonates, polyolefins and the like. The polymer may be a synthetic polymer. “ Synthetic polymers” include polymers derived from petroleum oil, such as polyolefins, aliphatic, semi-aromatic or aromatic polyesters, polyamides, polyamines, polycarbonates, polyurethanes and polyvinyl chloride or derived from natural polymers (also called bio-based polymers). “Natural polymers” include polymers derived from a material of natural origin, such as polylactic acid (PLA), polyamide and cellulose. In one embodiment, the natural polymer is a bio-based polyester. In general, these polyesters may be aliphatic polyesters. Bio-based polyesters may include, but are not limited to, polylactic acid, polyglycolic acid, poly-8-caprolactone, polyhydroxybutyrate, and any mixture thereof. Examples of synthetic fibers derived from petroleum oil are elastane fibers and acrylic fibers.

By “natural fiber” it is meant a fiber that is obtained directly from natural sources such as plants, animals or minerals. Examples of natural fibers include, but are not limited to, cotton, viscose, cellulose, flax, hemp, jute, ramie, wool and silk.

In the context of the invention, a polymer preferably refers to a thermoplastic polymer or a mixture of thermoplastic polymers. A thermoplastic polymer refers to a polymer that becomes moldable above a specific temperature and solidifies upon cooling. As examples of thermoplastic polymers, one can cite polyesters, polyurethanes, polyolefins or vinyl polymers and/or polyamides.

A “polyester” refers to a polymer that contains the ester functional group in its main chain. Ester functional group is characterized by a carbon bound to three other atoms: a single bond to a carbon atom, a double bond to an oxygen atom, and a single bond to an oxygen atom. The singly bound oxygen atom is bound to another carbon atom. According to the composition of their main chain, polyesters can be aliphatic, aromatic or semi-aromatic. Polyesters can be homopolymers or copolymers. As an example, polyethylene terephthalate is a semi-aromatic copolymer composed of two monomers: terephthalic acid and ethylene glycol.

A "polyamide” refers a polymer that contains amide (CONH) linkages in its main chain.

“Technical polymers” are well known by the skilled person and include poly etheretherketone (PEEK), polyamide-imides (PAI), polyimides (PI), polyphenylene sulfide (PPS), polyphenylsulfones (PPSU), polysulfones (PSU), polyethersulfones (PES) and polyetherimides (PEI).

“Depolymerization” , in relation to a polymer or a pre-treated textile waste containing a polymer, refers to a process by which a polymer or at least one polymer of said textile waste is depolymerized and/or degraded into smaller molecules, such as monomers and/or oligomers and/or any degradation products. According to the invention, the term “target polymer” refers to the polymer for which a depolymerization is intended.

The terms “amorphization” , “amorphized” and “amorphizing", in connection with a polymer, refer to a process or situation wherein the degree of crystallinity of a given polymer is decreased compared to its degree of crystallinity before the beginning of this process.

“Oligomers” refer to molecules containing from 2 to about 20 monomer units. As an example, oligomers retrieved from PET include diethylene glycol (DEG), tri-ethylene glycol (TEG), methyl -2-hydroxy ethyl terephthalate (MEET) and/or bi s(2-hydroxy ethyl) terephthalate (BEET) and/or 1 -(2 -hydroxy ethyl) 4-methyl terephthalate (HEMT) and/or dimethyl terephthalate (DMT).

As another example, monomers and/or oligomers of lactic acid may be retrieved from PLA.

As another example, monomers and/or oligomers of caprolactam may be retrieved from PA6 and monomers and/or oligomers of hexamethylene diamine and adipic acid may be retrieved from PA6,6.

By “opening step”, it is meant a step of opening the compressed bales of textile waste, preferably comprising entangled textiles and parts such as ferrous, non-ferrous metals and/or non-metallic waste.

In the context of the invention, “crystalline polymers” or “semi-crystalline polymers” are to be understood as well known in the art, for instance as defined in page 5, lines 1-28 of WO 2021/123299.

“T “Tc”, and “Tm” respectively refer to the glass transition temperature, the crystallization temperature, and the melting temperature of a polymer. Such temperatures may be determined by different analytical methods. For instance, Differential Scanning Calorimetry (DSC) or Differential thermal analysis (DTA), preferably DSC, may be used for determining the Tg, Tc, and/or Tm of polymers.

The terms “a”, “an”, and “the” refer to “one or more” when used in the subject specification, including the claims.

Unless otherwise indicated, all numbers expressing quantities of components, conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about” . Accordingly, unless indicated to the contrary, the numerical parameters set forth in the instant specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

As used herein, the term “abou ”, when referring to a value or to an amount of mass, weight, time, volume, concentration, and/or percentage can encompass variations of, in some embodiments +/-20%, in some embodiments +/- 10%, in some embodiments +/— 5%, in some embodiments +/— 1%, in some embodiments +/- 0.5%, and in some embodiments +/- 0.1%, from the specified amount, as such variations are appropriate in the disclosed methods.

As used herein, unless otherwise indicated, the percentage means weight percentage (% wt) and is relative to the total weight of the textile waste composition and/or of the pure textile of the textile waste.

The term "substantially free of' a component or a substance means the presence of less than 4%, preferably less than 3%, more preferably less than 2%, even more preferably less than 1% in weight of said component or substance. In some embodiments, the term “substantially free of of a component or a substance means the presence of less than or equal to 1.5%, such as less than or equal to 1.4%, less than or equal to 1.3%, less than or equal to 1.2%, in weight of said component or substance.

Textile waste

The textile waste provided at step a) comprises textiles and optionally substances or impurities that are not textiles, preferably fixed to textile. The textile waste may be provided in mixture with non-textile waste. The textile comprised in the textile waste comprises at least one target polymer.

In some embodiments, the target polymer is present in the textile waste in an amount of 15% or more, such as 20% or more, such as 30% or more, such as 35% or more in weight relative to the total weight of the textiles of the textile waste or of the pure textile material of the textile waste.

In some embodiments, the target polymer is present in the textile waste in an amount of 40% or more, such as 45% or more, such as 50% or more, such as 55% or more, such as 60% or more, such as 65% or more, such as 70% or more, such as 75% or more, such as 80% or more, such as 85% or more, such as 90% or more, such as 95% or more, such as 97% or more, such as 98% or more in weight relative to the total weight of the textiles of the textile waste or of the pure textile material of the textile waste.

In some embodiments, the target polymer is present in the textile waste in an amount comprised between 15 and 98%, between 20 and 97% in weight relative to the total weight of the textiles of the textile waste or of the pure textile material of the textile waste.

In some embodiments, the target polymer is present in the textile waste in an amount comprised between 25 and 70%, between 35 and 95% or between 70 and 95% in weight relative to the total weight of the textiles of the textile waste or of the pure textile material of the textile waste.

In some embodiments, the textiles or the pure textile material represent 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, such as 45% or more, such as 50% or more, such as 55% or more, such as of 60% or more, such as 65% or more, such as 70% or more, such as 75% or more, such as 80% or more, such as 85% or more, such as 90% or more, such as 95% or more, such as 98% or more of the textile waste, and the target polymer is present in an amount of 9% or more, such as 10% or more, 12% or more, 15% or more, 20% or more, 25 % or more , such as 30% or more, such as 35% or more, such as 40% or more, such as 45% or more, such as 50% or more, such as 55% or more, such as 60% or more, such as 65% or more, such as 70% or more, such as 75% or more, such as 80% or more, such as 85% or more, such as 90% or more, such as 95% or more, such as 98% or more in weight relative to the total weight of the textiles of the textile waste or of the pure textile material of the textile waste.

In some embodiments, the textiles or the pure textile material represent 40% or more, such as 45% or more, such as 50% or more, such as 55% or more, such as of 60% or more, such as 65% or more, such as 70% or more, such as 75% or more, such as 80% or more, such as 85% or more, such as 90% or more, such as 95% or more, such as 98% or more of the textile waste, and the target polymer is present in an amount of 25 % or more , such as 30% or more, such as 35% or more, such as 40% or more, such as 45% or more, such as 50% or more, such as 55% or more, such as 60% or more, such as 65% or more, such as 70% or more, such as 75% or more, such as 80% or more, such as 85% or more, such as 90% or more, such as 95% or more, such as 98% or more in weight relative to the total weight of the textiles of the textile waste or of the pure textile material of the textile waste.

In some embodiments, the textile waste comprises between 60% and 98%, preferably between 80% and 98%, more preferably between 90% and 98% of the pure textile material and the pure textile material comprises between 50% and 95%, preferably between 70 and 95% of the target polymer.

In some embodiments, the textile waste comprises between 15% and 95%, preferably between 60% and 98%, preferably between 80% and 98%, more preferably between 90% and 98% of the pure textile material and the pure textile material comprises between 9% and 98%, preferably between 50% and 95%, more preferably between 70 and 95% of the target polymer.

In some embodiments, the textile waste comprises 85wt.% or less, 80wt.% or less, 70wt.% or less, 60wt.% or less, 50wt.% or less, 40wt.% or less, 30wt.% or less, 20wt.% or less, 10wt.% or less, 5wt.% or less, 3wt.% or less, 2wt.% or less, lwt.% or less, of natural fibers and/or synthetic fibers.

In an embodiment, the textile waste comprises at least one synthetic polymer, such as polyolefins, aliphatic, semi-aromatic or aromatic polyesters, polyamides, polyamines, polycarbonates, polyurethanes and polyvinyl chloride, preferably selected from polyesters.

In an embodiment, the target polymer is a polyester, such as polyethylene terephthalate, a polyamide, a mixture thereof and/or a blend thereof.

In some embodiments, the textile waste further comprises natural fibers and/or synthetic fibers, wherein said natural fibers may be cotton fibers, viscose fibers, cellulose fibers, such as regenerated cellulose fibers, flax fibers, hemp fibers, jute fibers, ramie fibers, wool fibers and/or silk fibers and wherein said synthetic fibers may be elastane fibers and/or acrylic fibers.

In some embodiments, the textile waste further comprises polyurethane.

In some embodiments, the textile waste to be pre-treated according to the invention comprises, in addition to the target polymer, at least one “ other polymer” other than the target polymer. Said other polymer may be selected from the group consisting of cellulose, polyesters, polyamides, poly acrylates, polypropylene, polyether-polyurea copolymers, polyurethanes, lignocellulosic polymers, polysiloxanes, natural polymeric fibers, polyetheretherketones (PEEK), polyamide-imides (PAI), polyimides (PI), polyphenylene sulfides (PPS), polyphenylsulfones (PPSU), polysulfones (PSU), polyethersulfones (PES), polyetherimides (PEI), and any combination thereof. For instance, when the target polymer is at least one polyester, the textile waste may comprise at least one further polymer other than a polyester. In another example, when the target polymer is at least one polyamide, the textile waste may comprise at least one further polymer other than a polyamide. In some embodiments, the textile waste to be pre-treated according to the invention comprises a polymer material or blended textile. In some embodiments, the polymer material may be polyester, polyamide, viscose, or acrylic. In some embodiments, the blended textile may be cellulose/polymer blend material, polyester/wool blend material, polyester/acrylic blend material, acrylic/polyamide blend material, cotton/polyamide/elastane blend material, polyamide/elastane blend material, wool/acrylic/polyamide blend material, cotton/elastane blend material, wool/acrylic blend material, cotton/acrylic blend material, cotton/polyester/elastane blend material, cotton/viscose blend material, polyester/elastane blend material, wool/polyamide blend material, viscose/elastane blend material, viscose/polyamide blend material, polyester/viscose blend material, polyester/viscose/elastane blend material, preferably cotton/polyester blend material (also known as polycotton) or polyamide/polyester blend material.

The target polymer comprised in the textile waste pre-treated according to the invention may be a thermoplastic polymer, or a mixture of thermoplastic polymers. As examples of thermoplastic polymers, one can cite polyesters, polyurethanes, polyolefins, technical polymers, vinyl polymers and/or polyamides.

Examples of polyesters include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene isosorbide terephthalate (PEIT), polylactic acid (PL A), polyhydroxy alkanoate (PHA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polyethylene furanoate (PEF), polycaprolactone (PCL), poly(ethylene adipate) (PEA), polyethylene naphthalate (PEN), polycyclohexylenedimethylene terephthalate (PCT), polybutylene succinate terephthalate (PBST), polyethylene succinate (PES), poly(butylene succinate/terephthalate/isophthalate)-co-(lactate) (PBSTIL) and blends/mixtures of these materials.

Particularly, the polyester is selected from the group consisting of polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene isosorbide terephthalate (PEIT), polybutylene adipate terephthalate (PBAT), polyethylene furanoate (PEF), and blends/mixtures of these polymers.

In a particular embodiment, the polyester is PET or PLA, more preferably PET.

Examples of polyamides include polyamide-6 or poly(P-caprolactam) or polycaproamide (PA6), polyamide-6, 6 or poly(hexamethylene adipamide) (PA6,6 or nylon), poly(l l- aminoundecanoamide) (PAI 1), polydodecanolactame (PA12), poly(tetramethylene adipamide) (PA4,6), poly(pentamethylene sebacamide) (PA5,10), poly(hexamethylene azelaamide) (PA6,9), poly(hexamethylene sebacamide) (PA6,10), poly(hexamethylene dodecanoamide) (PA6,12), poly(m-xylylene adipamide) (PAMXD6), polyhexamethylene adipamide/polyhexamethyleneterephthalamide copolymer (PA66/6T), polyhexamethylene adipamide/polyhexamethyleneisophthalamide copolymer (PA66/6I) and blends/mixtures of these materials.

The inventors have developed a degrading process for degrading textile waste comprising polymers, preferably comprising thermoplastic polymers such as polyesters and/or polyamides. The process of the invention may be advantageously used with textile waste from textile waste collection, from post-industrial waste and/or from pre- or post-consumer waste.. The process of the invention may be used for degrading used textile fibers, such as fibers providing from fabrics, textiles and/or and industrial waste. More particularly, the process of the invention may be used with PET textile waste or PET fiber waste, such as PET fibers providing from fabrics or textiles.

In a particular embodiment, the process of the invention is used for degrading textile waste comprising at least one thermoplastic target polymer, particularly one semi-crystalline thermoplastic target polymer.

Pre-treatment process

The inventors have found that by carrying out the process for pre-treatment of textile waste according to the invention, the recovery of monomers from the target polymer material contained in the textile waste is improved in a safe, environmentally friendly and efficient manner. Thanks to this process, the yield of further treatment steps is improved. For instance, the yield of monomers and/or oligomers, preferably monomers, produced from the depolymerization step of the target polymer contained in the textile waste, is improved. Actually, the pre-treatment process according to the invention makes it possible to obtain shreds of textile waste having better flowability and/or to improve the control of the feeding rate into the extruder compared to the shredded material of the state of the art and substantially free of foreign substances/contaminants that are known for their ability to damage an extruder. The pre-treatment process according to the invention also makes it possible to facilitate the transport of the pre-treated waste before the subsequent steps. Steps a) to e) or f) are preferably implemented in this order. However, it is within the skill of one skilled in the art to determine if some steps can be reverted without affecting reaching the goal of the pre-treatment process of the invention. For instance, air stream separation step d), which is typically preformed after separation step c), may in certain cases be performed before separation step c), or even between the magnetic separation and the Eddy current separation of step c). In some embodiments, the steps are implemented as follows: step a), step b), step d) and step c).

Steps a) to e) or f) are preferably implemented in a continuous mode, meaning that textile waste providing step a) and recovering step e) are performed repeatedly or in a continuous manner while the pre-treatment process is running.

Additional steps of conveying the textile waste from and/or to the devices used for implementing each step may be present before step a), between step a) and step b), between step b) and step c), between step c) and step d), between step d) and step e), between step e and step f), after step f) and/or before, between or after any other steps of the process. Said conveying steps may be implemented with conveyor lines, such as belt conveyors. Belt conveyors are especially useful in that they can efficiently transport materials up steep inclines and are extremely versatile.

Preferably, the flow rate of textile waste provided at step a) and/or of pre-treated textile waste recovered at step e) is constant while the pre-treatment process is running.

• Providing step a)

Step a) consists in providing the textile waste to be pre-treated according to the invention. In some embodiments, step a) comprises loading the textile waste to the suitable device via a belt conveyor. The textile waste provided at step a) may be in any form. For instance, it may be provided as bulk textile waste, or as compressed bales of textile waste.

The textile waste can be provided at step a) in a continuous or discontinuous flow. Preferably, the textile waste is provided at step a) as a constant, and optionally monitored, flow rate.

• Shredding step b)

The textile waste provided at step a) is then loaded onto a shredder.

Shredding step b) may be implemented by any suitable grinding machine or shredding machine known in the art. The shreds shape and size may be adapted by one skilled in the art depending among others on the target polymer contained in the textile waste to be pre-treated, on the fraction of impurities that are fixed to the textile, and/or on the downstream recycling steps to be implemented.

The shredding machine, or shredder, is preferably configured for processing high volumes, while producing small pieces, also called shreds, having a mean size lower than 20 cm.

In some embodiments, the shreds mean size is lower than 20 cm, preferably lower than 15 cm, for instance it is less than 10 cm.

In an embodiment, shredding step b) is configured for giving one or unique output comprising the outgoing shreds.

The shreds may be of any shape, including strips, confetti, and heterogeneous shapes. The mean size of a shred is preferably calculated by considering all dimensions of the shred, except its thickness.

The shredding step is to be carried out prior to the next steps in order to reduce the textiles size, to tear apart and to shred the textile waste which comprises fixed impurities such as zippers and/or buttons, thereby allowing the process to go on with the next steps that cannot be implemented with great size textiles.

In some embodiments, the pre-treatment process according to the invention is automatically regulated. For instance, the pre-treatment process may comprise the detection, for instance with a level sensor, of the material thickness or size leaving the shredder at the end of step b). When such thickness or size exceeds a defined threshold, an auto-regulation loop allows slowing down or stopping the shredder and/or lowering the flow rate of textile waste entering shredding step b). Such auto-regulation contributes to the efficiency of the pre-treatment process of the invention by avoiding a too great amount of shredded textile waste to proceed to further separation steps c) and d). When a too great amount of shredded textile waste goes through separation steps c) and/or d), a risk exists that the separation step(s) are not performed as efficiently as desired.

• Separating step c)

The shreds obtained at step b) are then conveyed by any suitable means from the shredder to the magnetic separator(s) and/or the Eddy current separator(s).

The use of magnetic separators and/or of Eddy current separators is well known in the field of the treatment of waste, such as polymer waste, to remove metallic impurities. Magnetic separators remove the ferrous metals, such as iron or steel, from the textile waste.

Any suitable magnetic separator known in the art may be used for separating step c). The magnetic separator may be a magnetic pulley or a magnetic Overband Separator. The magnetic pulley consists of a cylindrical drum mounted on a shaft in which permanent magnets create a magnetic field. When the magnetic pulley is in operation, a conveyor belt or material flow passes over it. The ferrous material present in the material flow is attracted to the magnetic field created by the pulley. The ferrous materials may be directed to a bin by a conveyor with flights that runs along the magnet. The feed conveyor may be located directly under the magnet.

A magnetic Overband Separator is a device usually mounted over a conveyor belt. It consists of a stationary magnet unit with a strong magnetic field and a conveyor belt that carries the material to be separated. The magnetic field generated by the magnets extends over the conveyor belt and into the material flow. The conveyor belt carries the mixed material, which consists of both ferrous and non-ferrous components, under the magnetic field generated by the stationary magnet unit. Ferrous materials present in the material flow are attracted to the magnetic field. The magnetic force exerted by the magnet unit causes the ferrous particles to be pulled out of the material flow and adhere to the surface of the conveyor belt as it passes under the magnet. As the conveyor belt continues to move, the ferrous particles adhering to the belt are carried away from the material flow and reach the end of the conveyor. At this point, they are usually discharged into a separate collection container or chute.

The non-magnetic material continues along its intended path, unaffected by the magnetic field.

Vibrating conveyors or feeders may be incorporated in the process. In some embodiment, a vibrating feeder is incorporated between the magnetic separator and Eddy current separator to make the flow of the material wider and more homogeneous for distribution on conveyors and/or feeding into the Eddy current separator.

Separation with the Eddy current separator is especially useful for textile waste comprising substantial amounts of non-ferrous metallic impurities. Eddy current separation removes nonferrous metals based on conductivity. Non-ferrous metals, such as stainless steel, aluminum, copper, bronze, lead, chrome, tin, zinc may be extracted using Eddy current separation.

Step c) is implemented to separate ferrous and non-ferrous metals, and/or to separate the shreds comprising such ferrous and non-ferrous metals from the non-metallic waste and/or from the shreds comprising metal parts. Separating step c) also allows to get rid of un-separated metallic trash or other contaminants.

In one embodiment, following separating step c), the textile waste comprises 5 wt.% or less, such as 4% or less, preferably 3 wt.% or less of metal. The metal may be present as such and/or as metallic parts fixed to the textile.

Operation of the magnetic and/or Eddy current separator(s) can either be batch, semi-batch or continuous, preferably continuous.

In an embodiment, separating step c) comprises submitting at least part of, preferably all of, the shreds obtained at step b) to a magnetic field and to an Eddy current.

• Air stream step d)

Step d) aims at separating the lighter shreds from the heavier shreds and/or from heavier impurities which would not have been removed by the previous treatment steps. Heavier shreds may for instance comprise residual shreds comprising metallic parts, preferably non-ferrous metallic parts, or non-metallic hard parts, which would not have been removed at step c).

The lighter fraction typically comprises pure textile material, corresponding to textile shreds which do not comprise impurities that may hinder or affect the efficiency of the further treatment steps. In some embodiments, the lighter fraction comprises more than 70% of pure textile material, preferably more than 80%, more than 90%, more than 95% or more than 97% pure textile material.

The air stream separator can be a Zig Zag separator. The shreds entering the air stream separator may be for instance gravity-fed, for instance at the top of the separator, or introduced through a conveyor system. Due to gravity, the heavier shreds tend to roll down, for instance into a bin, while the lighter shreds continue to flow upwards.

The air stream separator can be a Nihot windshifter separator such as a Single Drum Separator for separating textile waste into two fractions, heavy and light by means of negative pressure, or suction. This method allows providing a most precise separation. In addition to the performance advantages, negative pressure also contributes to a dust-free environment.

• Recovering step e)

Recovering step e) may be performed with any suitable means known in the art. For example, the lighter shreds may be collected in a big bag or silo. The pre-treated textile waste is preferably recovered at step e) as a constant, and optionally monitored, flow rate.

The pre-treated textile waste recovered at step e) and/or f) is also an object of the present invention.

• Pre-treated textile waste

The pre-treated textile waste obtained at step e) preferably comprises 5wt.% or less, such as 4 wt.% or less, such as 3 wt.% or less, such as 2 wt.% or less, such as 1 wt.% or less, such as 0.5 wt.% or less of impurities (such as zippers, buttons, clothing accessories, rivets, . . .) exceeding a 4 mm size. More preferably, the pre-treated textile waste comprises no impurities exceeding a 4 mm size. This is especially important when the pre-treated textile waste is further treated by extrusion. Most extruders do not allow efficiently extruding a material comprising more than 4 mm size impurities.

• Packaging step f)

Step f) is optional. Step f) may for instance be a step of packaging at least part of, preferably all of, the pre-treated textile waste in the form of bales.

• Additional steps

The pre-treatment process according to the invention may comprise, before step a), between steps b) to e) and/or after step e) or step f) any other step, such as any other step known in the art for increasing the quality of the pre-treated textile waste obtained at step e). The quality may be increased depending on the further treatment step(s) which will be implemented on the pretreated textile waste. The quality may be increased for instance so as to maximize the yield and/or the efficiency of at least one of the further treatment step(s).

In some embodiments, the pre-treatment process comprises, before shredding step b), a preliminary step a’) implemented on the textile waste provided at step a). Preliminary step a’) may for instance be a sorting step, a coarsely pre-shredding step to separate the layers (lining, shoulder pads, etc.), an opening step, a chemolysis step, a solvolysis step, a dissolution step, a washing step, a disinfecting step, a sterilizing step and/or a biologically cleaning step. In some embodiments, preliminary step a’) is a sorting step, a coarsely pre-shredding step to separate the layers (lining, shoulder pads, etc.), a washing step, a disinfecting step, a sterilizing step and/or a biologically cleaning step. In some embodiments, step a’) is a sorting step aiming at increasing the amount of textile comprising a desired target polymer in the textile waste, by removing textiles not comprising the desired target polymer, and/or non-textile components from the textile waste provided at step a).

In some embodiments, the pre-treatment process further comprises an additional compaction step, densification step and/or pelletizing step. In some embodiments, the pre-treatment process further comprises an additional compaction step. In particular, said step may be implemented after step e) or f).

In some embodiments, the pre-treatment process comprises an additional dusting step. Said step may be implemented at any stage of the pre-treatment process, preferably after the shredding step b). In some embodiments, the dusting step is performed at the same time as the air stream separation step d). For instance, the dusting step may be implemented by connecting the air stream separator to a dust collection plant.

The dusting step aims at removing the generated small size solid contaminants such as polymer dust, cotton dust, and/or organic contaminants dust.

Downstream treatment process

The pre-treatment process according to the invention is preferably implemented as part of a global recycling process of textile waste comprising at least one target polymer. In this context, the pre-treated textile waste obtained with the process according to the invention may thus be submitted to at least one further treatment step.

Indeed, the inventors have found that when a textile waste is subjected to all the steps of the pre-treatment process of the invention, the obtained pre-treated textile waste presents a suitable flowability and can for instance pass through an extruder without damaging it. The flowability of the pre-treated textile waste according to the invention is higher than that of the textile waste before the pre-treatment, and the pre-treated textile waste is substantially free of foreign substances/contaminants. Such features are especially suitable to improve the efficiency and/or the yield of further treatment steps. For instance, the absence of foreign substances/contaminants is important when further treatment involves an extrusion step as they are known for their ability to damage an extruder.

The pre-treated textile waste obtained with the process according to the invention preferably presents physico-chemical properties that are specifically optimized for one or several of the further treatment steps that are to be implemented on the pre-treated textile waste. For instance, the physico-chemical properties may be optimized for one or several of transportation, conveying, storage, handling, dosing and incorporation into an extruder of the pre-treated textile waste.

In a preferred embodiment, the pre-treated textile waste of step e) or f) is ready or suitable to be submitted to an extrusion step. In other words, pre-treated textile waste of step e) or f) is suitable to be extruded, preferably suitable for extrusion before a depolymerization step.

In a preferred embodiment, the pre-treated textile waste of step e) or f) is substantially free of substances or impurities that are not textiles. In a more preferred embodiment, the pre-treated textile waste suitable to be submitted to an extrusion step is substantially free of substances or impurities that are not textiles.

The pre-treated textile waste obtained according to the invention preferably presents a suitable volumic mass or bulk density (apparent density). Preferably, the mean bulk density of the pretreated textile waste obtained according to the invention is higher than 40 kg/m³, preferably higher than 50 kg/m³. Such values are especially suitable as they are high enough to make easier and/or more efficient the transportation, conveying, storage, handling, dosing and incorporation into an extruder of the pre-treated textile waste, when compared to material with a lower mean volumic mass.

In some embodiments, the pre-treated textile waste obtained according to the invention presents a bulk density of at least 20 kg/m³, such as at least 25 kg/m³ , such as at least 30 kg/m³ , such as at least 35 kg/m³ , such as at least 40 kg/m³ preferably between 20 and 200 kg/m³.

The pre-treated textile waste obtained according to the invention preferably comprises 10wt.% or less, 5wt.% or less, 3wt.% or less, 2wt.% or less, lwt.% or less, of non-textile impurities.

The pre-treated textile waste obtained according to the invention preferably comprises 10wt.% or less, 5wt.% or less, 3wt.% or less, 2wt.% or less, lwt.% or less, of non-textile impurities with a size lower than 4 mm. In a preferred embodiment, the pre-treated waste obtained according to the invention preferably comprises 2% or less or 1% or less of non-textile impurities with a size lower than 4 mm.

• Extrusion Step

Performing an extrusion step on the pre-treated textile waste according to the invention is particularly advantageous when a further depolymerization step is to be performed, as the extrusion step allows improving the depolymerization rate of the target polymer comprised in the pre-treated textile waste.

In a preferred embodiment, the pre-treated textile waste according to the invention is further submitted to an extrusion, such as an extrusion-foaming. The extrusion is preferably carried out through an extruder. The extruder allows to submit a pre-treated textile waste both to a given temperature and to shear stress, simultaneously or sequentially. It is also possible to add degrading agent(s) in the extruder, if required. The extruder may further allow to cool the pretreated textile waste. Advantageously, the extruder is selected from single-screw extruders, multi-screw extruders of either co-rotating or counter-rotating design, planetary roller extruder, dispersive kneaders, reciprocating single-screw extruder (co-kneaders), mini extruder and internal mixer.

Extruders classically comprise a filter with a scrapper at the entrance of the stream, which retains all foreign substances or impurities with a size of 4 mm or more. The pre-treatment process according to the invention, which provides low amounts of non-textile impurities and of non-textile impurities with a size lower than 4 mm, is thus particularly suitable when the pretreated waste is further submitted to a process comprising at least an extrusion step.

The extrusion step allows to break at least partially the crystalline structure of the target polymer contained in the pre-treated textile waste, thereby improving the further depolymerization rate of the target polymer.

In a particular embodiment, the extrusion step comprises submitting the pre-treated textile waste to a temperature at which the target polymer contained in the pre-treated textile waste is in a partially or totally molten state.

In an embodiment, the extrusion step comprises submitting the pre-treated textile waste to a temperature above the crystallization temperature (Tc) of the target polymer of the pre-treated textile waste, preferably at or above the melting temperature (Tm) of said target polymer. Particularly, the pre-treated textile waste is submitted to a temperature corresponding to the Tm of said target polymer. Even more preferably, the pre-treated textile waste is submitted to a temperature corresponding to the Tm+5 to 25°C, preferably Tm+10 to 25°C, more preferably Tm+15 to 25°C, such as Tm+20°C of said target polymer. In another embodiment, the pretreated textile waste is submitted to a temperature corresponding to the Tm+25 to 50°C of said target polymer. In another preferred embodiment, the pre-treated textile waste is submitted to a temperature corresponding to Tm+50°C or above of said target polymer. According to the invention, the pre-treated textile waste may comprise different polymers. In such case, the pre-treated textile waste is advantageously submitted to a temperature at or above the Tc or at or above the Tm of the target polymer for which a depolymerization is intended. Alternatively, the pre-treated textile waste is submitted to a temperature at or above the highest Tc or Tm of the polymers contained in the pre-treated textile waste. Such embodiment may lead to the amorphization of all polymers contained in the pre-treated textile waste.

The temperature of the extrusion step can be adapted by a person skilled in the art depending on the target polymer. Generally speaking, the pre-treated textile waste shall be subjected to the heat treatment for a period of time sufficient to obtain amorphization of the target polymer. For instance, such duration may be comprised between 10 seconds and several minutes.

In a particular embodiment, the pre-treated textile waste comprises PET, and the extrusion step comprises submitting the pre-treated textile waste to a temperature above 170°C, preferably at or above 245°C, and more preferably between 250°C and 300°C. Even more preferably, the temperature is between 260°C and 280°C. In another embodiment, the temperature is 300°C or more, preferably between 300°C and 320°C.

In a particular embodiment, the pre-treated textile waste comprises polyamides, and the extrusion step comprises submitting the pre-treated textile waste to a temperature above 170°C, preferably at or above 200°C, and more preferably between 200°C and 300°C. Even more preferably, the temperature is between 210°C and 280°C. In another embodiment, the temperature is at or above 300°C.

In another particular embodiment, the pre-treated textile waste comprises PLA, and the extrusion step comprises submitting the pre-treated textile waste to a temperature above 110°C and more preferably at or above 145 °C.

In a particular embodiment, the pre-treated textile waste comprises PLLA, and the extrusion step comprises submitting the pre-treated textile waste to a temperature at or above 180°C.

In a particular embodiment, the extrusion step further comprises adding at least one degrading agent. Examples of degrading agents include, without limitation, water, monomers, alcohol, metal alkoxides, plasticizers, etc. Preferably, such degrading agents may be added during the heating phase of the pre-treated textile waste and/or the shear stress phase of the pre-treated textile waste. The extrusion step may be implemented for instance in the conditions disclosed in WO2017198786. o Extrusion-foaming step

In an embodiment, the extrusion step further comprises the addition of one or more foaming agent(s). The foaming agent(s) may be introduced during extruding, (e.g., in an extruder) before heating, during heating, and/or when the material has been heated and is already in a molten state. Such extrusion step is an extrusion-foaming step.

In the context of the invention, the “extrusion-foaming step" allows the creation of cells (or bubbles) in the structure of the target polymer contained in the textile waste by use of foaming agents, also called blowing agents. Gas generated by said foaming agents creates bubbles within the molten or the partially molten target polymer contained in the textile waste, forming closed- cells and/or opened-cells in the target polymer. The resulting foamed target polymer exhibits a cellular structure, which has a lower density than the target polymer density before the extrusion-foaming step.

Foaming agents can be classified as physical foaming agents or chemical foaming agents, depending on how the bubbles are generated.

In some embodiments, the extrusion step is implemented by use of one or more foaming agents selected from physical foaming agents, chemical foaming agents and any mixture thereof. In a particular embodiment, the extrusion step is implemented by use of physical foaming agent(s). Alternatively, the foaming step is implemented by use of chemical foaming agent(s). In another embodiment, the foaming step is implemented by use of both physical foaming agent(s) and chemical foaming agent(s). Extrusion-foaming may be performed by the person skilled in the art to break at least partially the crystalline structure of target polymer and particularly according to any process described in WO2021123299.

In the context of the invention, “physical foaming agents ” refer to compounds that undergo a physical change of state during processing. Physical foaming agents include pressurized gases (such as nitrogen, carbon dioxide, methane, helium, neon, argon, xenon, hydrogen and any mixture thereof) which expand when returning to atmospheric pressure during the process of foaming, and low-boiling-point liquids (such as pentane, isopentane, hexane, methylene dichloride, and dichlorotetra-fluoroethane) which expand when heated by changing from a liquid to a gaseous state and thereby produce a higher volume of vapor. In the context of the invention, “chemical foaming agents ” refer to foaming agents that undergo a decomposition reaction during target polymer heating at a given temperature, leading to the release of gas, such as nitrogen, carbon dioxide, carbon monoxide, nitroxide, NOx compounds, ammonia and/or vapor of water. Such chemical foaming agents can be selected from the group consisting of azides, hydrazides such as p,p’-hydroxybis-(benzenesulfonyl hydrazide), semicarbazides, such as p-toluenesulfonyl semicarbazide, p-toluenesulfonyl semicarbazide, azocompounds such as azodi carb oxami de, triazoles, such as nitrotri azol one, tetrazoles, such as 5-phenyltetrazole, bicarbonates, such as zinc bicarbonate or alkali bicarbonates such as sodium bicarbonate, anhydride, peroxide, nitrocompounds and perchlorates. Alternatively, the chemical foaming agents are selected from citric acid, carbonate and bicarbonate and any mixture thereof, or any commercial chemical foaming agent such as HYDROCEROL® from Clariant or Orgater® from Adeka. Preferably, the chemical foaming agents comprise a mix of citric acid and carbonate and/or a mix of citric acid and bicarbonate. Alternatively, the chemical foaming agent comprises hydrogen peroxide. In an embodiment, the extrusion-foaming step can be implemented using one or several of the chemical foaming agents listed above.

The nature of the foaming agents, the amount thereof and the moment of their addition into the process, may be as disclosed in WO2021123299. The foaming step helps lowering the porosity and/or the apparent density of the textile waste.

In a particular embodiment, the at least partially foamed textile waste comprises at least 95% PET and exhibits an apparent density Papp^er below 1000 kg.m'³, preferably below 900 kg.m'³. In an embodiment, the at least partially foamed textile waste exhibits a porosity rate between 40% and 70% and an apparent density Papp^er below 1000 kg.m'³. In a particular embodiment, the textile waste comprises at least 95% PET, and the at least partially foamed textile waste exhibits an apparent density Papp^er below 1000 kg.m'³ and a porosity rate above 30%. Preferably, the textile waste comprises at least 95% PET, and the at least partially foamed textile waste exhibits an apparent density Papp^er below 900 kg.m'³ and a porosity rate above 30%, preferably above 40%. o Cooling step

In a particular embodiment, the extrusion step, e.g. the extrusion-foaming step, further comprises a cooling step following the heating of the pre-treated textile waste. Such step allows to fix the target polymer contained in the pre-treated textile waste, which is at least partially molten, into an amorphized or amorphous state. Advantageously, the cooling is performed immediately after the heating.

In a particular embodiment, the cooling is performed by submitting the heated pre-treated textile waste to a temperature lower than the temperature of the pre-treated textile waste, in order to quickly reduce its temperature and to accelerate its solidification. Any method suitable for rapidly reducing the temperature of the target polymer contained in the pre-treated textile waste may be used.

The cooling step comprises contacting the extruded pre-treated textile waste to any cooling fluid, including air and/or liquid.

The temperature of the cooling step is lower than that of the extrusion step, preferably lower than 100°C, more preferably lower than 90°C.

In a particular embodiment, the cooling is performed by submitting the pre-treated textile waste to room temperature (i.e.; 25°C +/- 5°C). In another embodiment, the cooling is performed by submitting the pre-treated textile waste to a temperature of about 10°C, preferably about 5°C.

Generally speaking, the pre-treated textile waste coming out from the extrusion step is subjected to the cooling temperature for a period of time sufficient to decrease the temperature at the very heart of the textile waste. For instance, such period of time may be comprised between 1 second and several minutes, depending on the initial temperature of the textile waste coming out from the extrusion (i.e. before the cooling step), and/or the cooling temperature and/or the nature/form of the textile waste. In an embodiment, the textile waste is under an extrudate form with a diameter below 1cm, preferably between 0.5 and 5 mm and is submitted to the cooling temperature for less than 1 minute, preferably less than 30 seconds, more preferably less than 20 seconds, even more preferably less than 10 seconds. Alternatively, the pre-treated textile waste coming out of the extruder is shaped into tube or sheet.

The cooling step may be implemented as known in the art, for instance as disclosed in patent applications WO2017/198786 and WO2021/123299.

Another object of the invention is a process for recycling textile waste comprising at least one target polymer, comprising implementing the pre-treatment process according to the invention, and implementing at least one further step being an extrusion step, especially an extrusionfoaming step, and/or a depolymerization step of said at least one target polymer, especially an enzymatic depolymerization step. Further treatment process

Additionally or alternatively, the pre-treated textile can be submitted to recycling treatment techniques that are well known in the art. Said treatment techniques comprise mechanical recycling and chemical recycling. For instance, the pre-treated textile waste obtained according to the invention may be further submitted to at least one of: a pyrolysis, a gasification, a depolymerization, a chemolysis, solvolysis, and/or dissolution.

When a step of chemical dissolution is performed on the pre-treated textile waste according to the invention, it may be performed in presence of a chemical agent that is suitable to at least partly remove colored dye(s), such as ethyl benzoate.

In some embodiments, the pre-treated textile is submitted to an acid hydrolysis in order to separate the target polymer from natural fibers contained in the textile waste, such as cotton.

The cotton may then be converted into glucose. Preferably, the obtained pre-treated textile is further submitted to an extrusion step.

Process for degrading a target polymer

A further object of the invention is a process for degrading at least one target polymer of textile waste, comprising: i) submitting textile waste comprising at least one target polymer to a pre-treatment process according to the invention, ii) contacting the pre-treated textile waste obtained at step i) with a depolymerizing agent, in conditions suitable for depolymerizing said at least one target polymer, to obtain a mixture comprising oligomers and/or monomers of said at least one target polymer, and iii) recovering and optionally purifying the oligomers and/or monomers obtained at step ii).

Step i) of implementing the pre-treatment process according to the invention allows increasing the yield and/or the kinetics of depolymerizing step ii). Especially, it allows increasing the yield in monomers obtained after depolymerization.

• Depolymerization step

According to the invention, the degrading process comprises, following the optional extrusion and/or cooling steps, a step of depolymerization of at least one target polymer of the textile waste. According to a preferred embodiment, the depolymerizing step targets at least one target polymer that has been previously extruded. Particularly, the depolymerizing step is a chemical depolymerization or a biological depolymerization. In a preferred embodiment, the depolymerization is a hydrolysis, preferably a hydrolysis in alkaline conditions, more preferably an alkaline enzymatic depolymerization or an alkaline chemical depolymerization such as saponification, even more preferably an alkaline enzymatic depolymerization.

Within the context of the invention, “hydrolysis” refers to the rupture of the ester bond by means of OH ions in the presence of water, regardless of whether the reaction is a biological or chemical depolymerization. For example, the hydrolysis of PET produces terephthalic acid and ethylene glycol. In a preferred embodiment, the hydrolysis is an alkaline hydrolysis, wherein an alkali (or a base) is employed as a reactant to break down the polyester in an aqueous media. Such alkali can be selected from NaOH, KOH, NH4OH or LiOH. As an example, the alkaline hydrolysis of PET produces terephthalic acid (TA) salts and ethylene glycol (MEG).

In a particular embodiment, the depolymerizing step comprises contacting the textile waste with a depolymerizing agent, such as a chemical and/or a biological depolymerizing agent.

Advantageously, the depolymerization step is performed in a liquid medium comprising the depolymerizing agent.

In an embodiment, the depolymerization step is a chemical depolymerization.

Within the context of the invention, the term “chemical depolymerization” refers to a process by which the depolymerization of the at least one target polymer is performed by contacting said at least one target polymer contained in the textile waste with a chemical reagent, such as methanol or water, optionally in the presence of one or more chemical agent(s) such as a catalyst. These methods are respectively known as methanolysis and chemical hydrolysis. Other methods include glycolysis, aminolysis and ammonolysis. The methanolysis of PET produces dimethyl terephthalate (DMT) and mono-ethylene glycol (MEG).

The chemical agent(s) may be a catalyst selected from metallic catalysts or stables and nontoxic hydrosilanes (PMHS, TMDS) such as commercially available B(CeFs)3 and [PhsC⁺, B(C6FS)E] catalysts. Particularly, the catalyst is selected from alkoxide, carbonate, acetate, hydroxide, alkaline metal oxide, alkaline earth metal, calcium oxide, calcium hydroxide, calcium carbonate, sodium carbonate, iron oxide, zinc acetate, zeolite. In some embodiments, the catalyst used in the depolymerization process of the present invention comprises at least one of germanium compounds, titanium compounds, antimony compounds, zinc compounds, cadmium compounds, manganese compounds, magnesium compounds, cobalt compounds, silicon compounds, tin compounds, lead compounds, and aluminum compounds. Particularly, the catalyst comprises at least one of germanium dioxide, cobalt acetate, titanium tetrachloride, titanium phosphate, titanium tetrabutoxide, titanium tetraisopropoxide, titanium tetra-n- propoxide, titanium tetraethoxide, titanium tetramethoxide, a tetrakis(acetylacetonato)titanium complex, a tetrakis(2,4-hexanedionato)titanium complex, a tetrakis(3,5- heptanedionato)titanium complex, a dimethoxybis(acetylacetonato)titanium complex, a diethoxybis(acetylacetonato)titanium complex, a diisopropoxybis(acetylacetonato)titanium complex, a di-n-propoxybis(acetylacetonato)titanium complex, a dibutoxybis(acetylacetonato)titanium complex, titanium dihydroxybisglycolate, titanium dihydroxybisglycolate, titanium dihydroxybislactate, titanium dihydroxybi s(2- hydroxypropionate), titanium lactate, titanium octanediol ate, titanium dimethoxybistriethanol aminate, titanium diethoxybistriethanol aminate, titanium dibutoxybistriethanol aminate, hexamethyl dititanate, hexaethyl dititanate, hexapropyl dititanate, hexabutyl dititanate, hexaphenyl dititanate, octamethyl trititanate, octaethyl trititanate, octapropyl trititanate, octabutyl trititanate, octaphenyl trititanate, a hexaalkoxy dititanate, zinc acetate, manganese acetate, methyl silicate, zinc chloride, lead acetate, sodium carbonate, sodium bicarbonate, acetic acid, sodium sulfate, potassium sulfate, zeolites, lithium chloride, magnesium chloride, ferric chloride, zinc oxide, magnesium oxide, calcium oxide, barium oxide, antimony trioxide, and antimony triacetate. Alternatively, the catalyst is selected from nanoparticules. The chemical agent can be selected from any catalyst known by a person of the art for having the capacity to chemically degrade and/or depolymerize the target polymer.

In another embodiment, the depolymerization step is a biological depolymerization, preferably a hydrolysis, more preferably an enzymatic depolymerization. Preferably, the biological depolymerization is an alkaline enzymatic depolymerization.

The term “ biological depolymerization” refers to a process by which the depolymerization of the at least one target polymer is performed by contacting said at least one target polymer contained in the textile waste with a biological agent capable of degrading said target polymer. The biological depolymerization is carried out by hydrolysis. In a preferred embodiment, the hydrolysis is an alkaline hydrolysis.

In a particular embodiment, the depolymerizing agent is a biological depolymerizing agent. In a preferred embodiment, the biological depolymerizing agent is an enzyme. Preferably, the enzyme is able to degrade the at least one target polymer of the textile waste, more preferably a polyester contained in textile waste. In some embodiments, the enzyme is able to degrade the at least one target polymer that has been previously amorphized, for instance by extrusion.

In a more preferred embodiment, the enzyme is a depolymerase. The depolymerase is advantageously selected from the group consisting of a cutinase, a lipase, a protease, a carboxylesterase, a p-nitrobenzylesterase, an esterase, a scl-PHA depolymerase, a mcl-PHA depolymerase, a PHB depolymerase, an amidase, aryl-acylamidase (EC 3.5.1.13), oligomer hydrolase, such as 6-aminohexanoate cyclic dimer hydrolase (EC 3.5.2.12), 6-aminohexanoate dimer hydrolase (EC 3.5.1.46), 6-aminohexanoate-oligomer hydrolase (EC 3.5.1. Bl 7), oxidase, peroxidase, laccase (EC 1.10.3.2), oxygenase, lipoxygenase, mono-oxygenase, or lignolytic enzyme. In a particular embodiment, the textile waste is contacted with at least two different depolymerases.

Preferably, the depolymerase is selected from the group consisting of a cutinase, a lipase, a protease, a carboxylesterase and an esterase, more preferably a cutinase.

In another embodiment, the pre-treated textile waste is contacted with a depolymerizing agent before the depolymerization step. Particularly, the pre-treated textile waste may be contacted with the depolymerizing agent during the cooling step following the extrusion step (i.e. immersed in a cooling liquid comprising a depolymerizing agent). In an embodiment, the depolymerization step is subsequently performed by immersing the textile waste in a liquid. In a preferred embodiment, such liquid is deprived of depolymerizing agent. In another embodiment, the depolymerization step is performed by submitting the textile waste to composting conditions. Particularly, the textile waste may be submitted to industrial compost conditions at a temperature above 50°C, and/or to domestic compost conditions at a temperature between 15°C and 35°C. In an embodiment, the pre-treated textile waste is contacted with the depolymerizing agent during the cooling step and the depolymerization step is further implemented by submitting the textile waste to stimuli able to activate the depolymerizing agent. For instance, the depolymerizing agent may be a degrading enzyme and the stimuli consist in specific temperature and/or humidity rates.

In a particular embodiment, when textile waste comprises PET as target polymer, the depolymerase is an esterase. Particularly, the depolymerase is a cutinase, preferably a cutinase produced by a microorganism selected from Thermobifida cellulosityca, Thermobifida halotolerans, Thermobifida fusca, Thermobifida alba, Bacillus subtilis, Fusarium solani pisi, Humicola insolens, Sirococcus conigenus, Pseudomonas mendocina and Thielavia terrestris, or any functional variant thereof. In another embodiment, the cutinase is selected from a metagenomic library such as LC-Cutinase described in Sulaiman et al., 2012 or the esterase described in EP3517608, or any functional variant thereof including depolymerases listed in WO 2018/011284 or WO 2018/011281. In another particular embodiment, the depolymerase is a lipase preferably produced by Ideonella sakaiensis. In another particular embodiment, the depolymerase is a cutinase produced by Humicola insolens, such as the one referenced A0A075B5G4 in Uniprot or any functional variant thereof. In another embodiment, the depolymerase is selected from commercial enzymes such as Novozym 51032 or any functional variant thereof.

In a particular embodiment, when the textile waste comprises PLLA, the depolymerase is a protease, preferably produced by a microorganism selected from Amycolatopsis sp., Amycolatopsis orientalis, Tritirachium album (proteinase K), Actinomadura keratinilytica, Laceyella sacchari LP175, Thermus sp. or any commercial enzymes known for degrading PLA such as Savinase®, Esperase®, Everlase® or any functional variant thereof including depolymerases listed in WO 2016/062695, WO 2018/109183 or WO 2019/122308.

In another particular embodiment, when the textile waste comprises PDLA, the depolymerase is an esterase, preferably a cutinase or a lipase more preferably selected from CLE from Cryptococcus sp., lipase PS from Burkholderia cepacia, Paenibacillus amylolyticus TB-13, Candida Antarctica, Rhiromucor miehei, Saccharomonospora viridis, Cryptococcus magnus or any functional variant thereof.

In another particular embodiment, when the textile waste comprises polyamide (PA), the depolymerase is selected from the group consisting of amidase, aryl -acylamidase (EC 3.5.1.13), oligomer hydrolase, such as 6-aminohexanoate cyclic dimer hydrolase (EC 3.5.2.12), 6- aminohexanoate dimer hydrolase (EC 3.5.1.46) and 6-aminohexanoate-oligom er hydrolase (EC 3.5.1.B17).

In another particular embodiment, when the textile waste comprises polyolefin, the depolymerase is an oxidase preferably selected from the group consisting of laccase, peroxidase, oxygenase, lipoxygenase, mono-oxygenase and lignolytic enzyme.

In another embodiment, the depolymerizing agent is a microorganism that expresses and excretes the depolymerase. Said microorganism may naturally synthesize the depolymerase, or it may be a recombinant microorganism, wherein a recombinant nucleotide sequence encoding the depolymerase has been inserted, using for example a vector. Particular embodiments of the depolymerization can be found in WO 2017/198786.

According to the invention, several microorganisms and/or purified enzymes and/or enzymes may be used together or sequentially to depolymerize different kinds of polymers contained in a same textile article or in different textile products of the textile waste.

The time required for depolymerization of at least one target polymer of the pre-treated textile waste may vary depending on the textile waste and the target polymer (i.e., nature and origin of the textile waste, its composition, shape, molecular weight, etc.), the type and amount of microorganisms/enzymes used, as well as various process parameters (i.e., temperature, pH, additional agents, etc.). One skilled in the art may easily adapt the process parameters to the textile waste and/or depolymerases.

In a particular embodiment, the textile waste comprises PET, and the depolymerization step is implemented at a temperature comprised between 20°C and 90°C, preferably between 30°C and 80°C, more preferably between 40°C and 75°C, more preferably between 50°C to 75°C, even more preferably between 60°C to 75°C. Furthermore, the depolymerization step is preferably implemented at a pH between 5-11, preferably between 7-9, more preferably between 7-8.5, even more preferably between 7-8. Alternatively, the depolymerization step may be implemented under industrial and/or composting conditions.

In a particular embodiment, the textile waste comprises PLA, and the depolymerization step is implemented at a temperature comprised between 20°C and 90°C, preferably between 20°C and 60°C, more preferably between 30°C and 55°C, more preferably from 40°C to 50°C, even more preferably at 45°C. Furthermore, the depolymerization step is preferably implemented at a pH between 5-11, preferably between 7-10, more preferably between 8.5-9.5, even more preferably between 8-9. In another particular embodiment, the depolymerization step may be implemented at a pH between 7 and 8. Alternatively, the depolymerization step may be implemented under industrial and/or composting conditions.

In an embodiment, the process for degrading at least one target polymer of textile waste according to the invention comprises the following steps: i) submitting textile waste comprising at least one target polymer to a pre-treatment process according to the invention, ii) submitting the pre-treated textile waste obtained at step i) to an extrusion step, preferably an extrusion-foaming step, to obtain an extruded pre-treated textile waste, iii) contacting the extruded pre-treated textile waste obtained at step ii) with a depolymerizing agent, in conditions suitable for depolymerizing said at least one target polymer, to obtain a mixture comprising oligomers and/or monomers of said at least one target polymer, and iv) recovering and optionally purifying the oligomers and/or monomers obtained at step iii).

It is also another object of the invention to provide a method of producing monomers and/or oligomers and/or degradation products from a textile waste comprising at least a target polymer, comprising submitting successively the textile waste to a pre-treatment according to the invention, a foaming step to foam at least partially said textile waste, optionally to a cooling step to amorphize at least partially said target polymer of the textile waste, and then to a depolymerization step.

It is also another object of the invention to provide a process of degrading a textile waste comprising at least one target polymer, wherein the textile waste has been previously pre-treated according to the invention and foamed, wherein the target polymer of said textile waste has been optionally at least partially amorphized and wherein the textile waste is contacted with a depolymerizing agent able to degrade said target polymer.

It is also another object of the invention to provide a process of degrading a textile waste further comprising a step of purification of the monomers and/or oligomers and/or degradation products resulting from the step of depolymerization. Monomers and/or oligomers and/or degradation products resulting from the depolymerization may be recovered, sequentially or continuously. A single type of monomers and/or oligomers or several different types of monomers and/or oligomers may be recovered, depending on the polymers and/or the starting textile waste. The recovered monomers and/or oligomers and/or degradation products may be purified, using all suitable purifying method and conditioned in a re-polymerizable form. In a preferred embodiment, the repolymerizable monomers and/or oligomers may then be reused to synthesize polymers. One skilled in the art may easily adapt the process parameters to the monomers/oligomers and the polymers to synthesize.

It is a further obj ect of the invention to provide a method for recycling a textile waste comprising at least one target polymer, comprising subjecting successively said at least one textile waste to a pre-treatment according to the invention, a foaming step and a depolymerization step, and recovering monomers and/or oligomers of such target polymer.

It is also an object of the invention to provide a process for degrading a pre-treated and at least partially foamed textile waste comprising at least one target polymer, wherein the at least partially pre-treated foamed textile waste is produced from textile waste and is contacted with a depolymerizing agent able to degrade said at least one target polymer. In a particular embodiment, said target polymer of said at least partially foamed textile waste has been amorphized, and said at least partially pre-treated and foamed textile waste is contacted with a depolymerase to degrade said amorphized target polymer.

All particular embodiments exposed above in connection with the process for degrading textile waste also apply to the methods of producing monomers and/or oligomers.

Device

Another object of the invention is a device suitable for implementing at least the pre-treatment process according to the invention. A device according to the invention may comprise, preferably in this order:

1) at least one conveyer belt, suitable for providing textiles, such as bulk textiles or compressed textile bales,

2) at least one grinder and/or shredder,

3) at least one magnetic separator,

4) at least one Eddy current separator, and

5) at least one air stream separator.

The device may comprise additional modules, before, between or after the above-listed modules. For instance, the device may further comprise an unloading hopper after the Eddy current separator, and/or a module for packaging the textile in the form of bales after the air stream separator.

The air stream separator may be a zigzag separator.

The device may further comprise conveyor lines, such as belt conveyors for conveying the textile waste from and/to the devices used for implementing each step. The invention will also be described in further detail in the following examples, which are not intended to limit the scope of this invention, as defined by the attached claims.

EXPERIMENTAL PART

Al- Process for the pre-treatment of textile waste comprising polyester according to the invention

Example Al-1: a) Providing textile waste comprising PET

Post-consumer clothes issued from an automatic sorting and comprising a heterogeneous PET content varying between 75% and 95% have been used. The used clothes were composed of discarded clothes such as trousers, dresses and t-shirts, some of the clothes having visible impurities, such as metallic zippers or other metallic accessories. b) Shredding the textile waste

A flow rate of approximately 200 kg/h of the textile waste provided at step a) was constantly and continuously loaded onto a heavy-duty infeed conveyor belt and introduced into a single shaft shredder WLK1500 - Weima. The parameters of the shredder were adjusted with an intensity between 45 A and 59 A to regulate the feeding of the textile waste in the shredder and obtain shreds. c) Submitting the shreds obtained at step b) to a magnetic field and to an Eddy current

The shreds were then discharged onto a conveyor belt equipped at the top with a neodymium magnetic drum to remove the ferrous metals from the shreds and then entered through a vibro feeder conveyor into an Eddy current separator (RCSX D-75 NEO - IMRO) comprising a separator belt and a magnetic drum. The separator belt and the magnetic drum of the Eddy current system were set to 80% and 95% of their maximum speed respectively.

At the end of this step, the shreds comprising metallic parts were separated from the shreds not comprising metallic parts. The shreds comprising metallic parts were collected in a bin. d) Submitting the shreds to an air stream

The shreds not comprising metallic parts separated at step c) were submitted to a Zig zag sifter (MFT 55/500 - NEUE HERBOLD) to obtain a light and a heavy fractions. The frequency of the motor with variator was set to 22 Hz. e) Recovering the pre-treated textile waste The lighter fraction obtained at step d) which comprises the pre-treated textile waste (without hard points) was packed in Big Bags. The heavier fraction of the shreds (i.e., the hard points/non-metallic parts) was collected in a bin.

Example Al-2 a) Providing textile waste comprising PET

The textile waste are post-consumer clothes as described in example Al. b) Shredding the textile waste

The shredding was performed as described in example Al. c) Submitting the shreds obtained at step b) to a magnetic field

The shreds obtained from step b) were then gradually discharged onto a conveyor belt equipped at the top with a neodymium magnetic drum to remove the ferrous metals from the shreds. d) Submitting the shreds obtained at the previous step to air stream

Then the shreds obtained at the previous step were submitted to a Zig zag sifter (MFT 55/500 - NEUE HERBOLD) to obtain a light and a heavy fraction. The frequency of the motor with variator was set to 22 Hz. e) Recovering the pre-treated textile waste

The shreds were then collected in a Big Bag as described in example Al.

Example Al-3 a) Providing textile waste comprising PET

The shredding was performed as described in example Al. c) Submitting the shreds obtained at step b) to air stream

100kg of shreds from step b) were submitted to a Zig zag sifter (MFT 55/500 - NEUE HERBOLD) to obtain a light and heavy fractions. The frequency of the motor with variator was set to 22 Hz. d) Submitting the shreds obtained at step c) to a magnetic field

The shreds were then discharged onto a conveyor belt equipped at the top with a neodymium magnetic drum to remove the ferrous metals from the shreds. e) Recovering the pre-treated textile waste

The shreds were then collected in a Big Bag as described in example Al.

A2. Characterization of the pre-treated textile waste

The shreds obtained from examples Al-1, Al -2 and Al -3 have been submitted to characterization of bulk density and residual hard points ratio.

-Bulk density evaluation:

The bulk density was measured by determining the weight of a known volume of material.

IL graduated vessel has been used. The shreds have been filled in the vessel without compacting and then weighed.

-Residual hard points ratio

3 samples of 1 kg each were taken from each embodiment to quantify the amount of heavy points residues by manual sorting followed by weighing the heavy points residues and calculating the weight ratio.

The 3 samples have been extracted from the top, the middle and the bottom of the Big Bag packed shreds for each embodiment. Table 1 below presents the results.

Table 1 : Average weight ratio of residual heavy points in final shreds for different implementations of the process according to the invention Bl - A process for recycling the pre-treated textile waste comprising a polyester obtained according to the invention a) Submitting the pre-treated textile waste obtained at step i) to an extrusion step

Two different samples, each of 2kg of the pre-treated textile waste obtained from the pretreatment process according to the invention were collected at two different times and submitted to an extrusion step using a twin-screw extruder Leistritz ZSE 18 MAXX which comprises nine successive heating zones (Z1 - Z9) and a die plate (Z10) wherein the temperature may be independently controlled and regulated in each zone.

Temperature set from the feeding zone to the die plate was set to : 250^oC-260°C-280^oC-280°C- 270°C-260^oC-230^oC-230^oC-230°C. The screw speed (rpm) set to 200 rpm.

The molten sample arrived in the screw head (Z10) comprising a die plate with one hole of 3.5 mm and was immediately immersed in a 2 m long cold-water bath (10°C). The resulting extrudate was granulated into 2-3 mm solid pellets. Obtained pellets were then micronized with a 500pm grid with a prior immersion in liquid nitrogen. b) Determination of PET content in the extruded pre-treated textile waste by chemical

The chemical depolymerization was carried out in triplicate in 15 mL glass tubes (Supelco, 27162) with screw cap. A sample of - 40-50 mg of each sample of extruded pre-treated textile waste was placed in a glass tube and a total of 800 pL of dichloromethane (DCM) and 400 pL of methanol/potassium hydroxide KOH (3M) were added. The mixture was stirred during 2 hours by magnetic stirring at room temperature RT (~ 25 ° C). The solvents were evaporated under a flow of N2 for at least 10 min. The PET monomers were dissolved in 14 mL of milliQ water. The solution was stirred for 1 hour at RT. The amount of terephthalic acid equivalent (TA) and mono-ethylene glycol (MEG) was determined by Ultra High-Performance Liquid Chromatography (UHPLC) according to the method described below.

The MEG concentration was determined by mixing 1.5 mL of sample with 0.5 mL of H2SO4. After homogenization and filtration through a 0.45 pm syringe filter, 20 pL of sample were injected into the UHPLC, Ultimate 3000 UHPLC system (Thermo Fisher Scientific, Waltham, MA) including a pump module, a sampler automatic, a column thermostated at 55 ⁰ C and a RI (refractive index) detector. The MEG molecules were separated by means of a HPLC Aminex HPX-87H ion exclusion column (300 mm x 7.8 mm, 9 pm) equipped with a precolumn (Supelco, Bellefonte, PA). MEG was eluted with H2SO45mM using a flow rate of 0.8 mL min f MEG was measured according to standard curves prepared from commercially available MEG.

The terephthalic acid (TA) equivalent concentration was determined by chromatography (UHPLC). If necessary, the samples were diluted in 100 mM potassium phosphate buffer, pH 8. 1 mL of samples or diluted samples were mixed with 1 mL of methanol and 100 pL of 6 N HC1. After homogenization and filtration through a 0.45 pm syringe filter, 20 pL of sample were injected into the UHPLC, Ultimate 3000 UHPLC system (Thermo Fisher Scientific, Waltham, MA) including a pump module, a sampler automatic, a column thermostated at 25 ⁰ C and a UV detector at 240 nm. The terephthalic acid was separated using a gradient of methanol (30% to 90%) in 1 mM H2SO4 at 1 m/min through a HPLC Discovery HS C18 column (150 mm x 4.6 mm, 5 pm) equipped with a precolumn (Supelco, Bellefonte, PA). TA amount was measured according to standard curves prepared from commercially available AT.

The percentage of PET was calculated based on the total amount of TA and MEG and evaluated to 77% for Sample 1 and 92% for Sample 2. c) Depolymerization step of micronized powder

The depolymerization process was carried out in 500 mL Mini-bioreactors (Global Process Concept, France) using a variant of LC-cutinase (Sulaiman et al., Appl Environ Microbiol. 2012 Mar). Such variant corresponding to the enzyme of LC-cutinase with the following mutations F208I + D203C + S248C + V170I + Y92G, as compared to the wild-type LC-Cutinase was expressed as recombinant protein in Bacillus subtilis. 84 mg of a variant of LC-cutinase prepared in 224 mL of 100 mM potassium phosphate buffer, pH 8, was combined with 42 g of pretreated and extruded textile PET samples (obtained from step Bia). Temperature was regulated at 55°C and a marine turbine was used to restrain constant agitation at 250 rpm. The pH was regulated to 8 with NaOH 25% w and controlled by the GX controler with the C- BIOTM software (Global Process Concept, France). The NaOH consumption was recorded during the process time.

The depolymerization rate of PET was determined by measuring via UHPLC the amount of MEG and terephthalic acid equivalent produced according to the method previously described in step Bib).

Sample 1 whose PET content has been evaluated at 77%, displayed a PET hydrolysis rate of 66% in 3 Oh. Sample 2 whose PET content has been evaluated at 92%, displayed a PET hydrolysis rate of 88% in 30h.

B2 - A process for recycling the textile waste comprising a polyester

A comparative example was prepared with the PET rich post-consumer clothes as provided in step A-a) and submitted to a shredding step as in step A-b). In this comparative example, shredded textile waste was not submitted to a magnetic field, to an Eddy current, nor to an air stream separation before being further recycled.

The materials were then submitted to the recycling process as detailed in step Bl. However, when the materials were introduced in the extruder of step B-a), it was obvious that the impurities naturally contained in the textile waste hindered the extruder and stopped the extrusion. Therefore, it was not possible to proceed with the further steps of depolymerizing the polyester contained in the textile waste.

Claims

1. A process for the pre-treatment of textile waste comprising at least one target polymer to obtain pre-treated textile waste suitable to be submitted to an extrusion step, comprising the following steps: a) providing textile waste comprising at least one target polymer, b) shredding the textile waste provided at step a) to obtain shreds, wherein the shreds comprise shreds comprising metallic parts and/or shreds not comprising metallic parts, c) separating at least part of the shreds comprising metallic parts from the shreds not comprising metallic parts by submitting at least part of the shreds obtained at step b) to a magnetic field and/or an Eddy current, d) submitting the shreds not comprising metallic parts separated at step c) to an air stream, to obtain a lighter fraction and a heavier fraction, e) recovering the lighter fraction obtained at step d), said lighter fraction comprising pretreated textile waste, and f) optionally packaging the pre-treated textile waste.

2. A process for recycling textile waste comprising at least one target polymer, comprising implementing the pre-treatment process according to claim 1, and implementing at least one further step being an extrusion step, such as an extrusion-foaming step, and/or a depolymerization step, such as a hydrolysis step, preferably an alkaline hydrolysis step.

3. The process according to claim 1 or claim 2, wherein the at least one target polymer is a thermoplastic polymer, preferably selected from the group consisting of polyesters, polyamides and mixtures and/or blends thereof, more preferably polyesters, in particular PET.

4. The process according to any one of claims 1 to 3, wherein the textile waste comprises one target polymer and at least one further polymer other than the target polymer, the further polymer being preferably selected from the group consisting of cellulose, polyesters, polyamides, polyacrylates, polypropylene, polyether-polyurea copolymers, polyurethanes, lignocellulosic polymers, polysiloxanes, natural polymeric fibers, polyetheretherketones (PEEK), polyamide-imides (PAI), polyimides (PI), polyphenylene sulfides (PPS), polyphenylsulfones (PPSU), polysulfones (PSU), polyethersulfones (PES), Polyetherimides (PEI), and combinations thereof.

5. The process according to any one of claims 1 to 4, wherein the pre-treatment process comprises, before shredding step b), a preliminary step a’) selected from the group consisting of a sorting step, a coarse pre-shedding step, an opening step, a chemolysis step, a solvolysis step, a dissolution step, a washing step, a disinfecting step, a sterilizing step, a biologically cleaning step and any combination thereof.

6. The process according to any one of claims 1 and 3 to 5, wherein the pre-treated textile waste is further submitted, after recovering step e), to one or more steps selected from the group consisting of a compaction step, a densification step, a pelletizing step, an extrusion step, preferably an extrusion-foaming step, a pyrolysis step, a gasification step, a depolymerization step, a chemolysis step, a solvolysis step and a dissolution step.

7. The process according to claim 6, wherein the pre-treated textile waste is submitted to an extrusion step, preferably an extrusion-foaming step, more preferably performed in an extruder, optionally followed by a depolymerization step.

8. The process according to claim 7, wherein the extrusion step, preferably the extrusionfoaming step, is performed at a temperature at which at least one target polymer comprised in the pre-treated textile waste is in a partially or totally molten state.

9. The process according to claim 7 or claim 8, wherein the extrusion step is implemented with a physical foaming agent, preferably selected from gas, more preferably selected from the group consisting of nitrogen, carbon dioxide, methane, helium, neon, argon, xenon, hydrogen and any mixture thereof, or with a chemical foaming agent, preferably selected from the group consisting of citric acid, carbonate and any mixture thereof.

10. The process according to any one of claims 7 to 9, wherein the extrusion step is followed by a cooling step, preferably wherein the cooling step is performed at a temperature below 100°C, more preferably below 90°C.

11. The process for recycling textile waste according to claim 2, comprising: i) submitting textile waste comprising at least one target polymer to a pre-treatment process according to any one of claims 1 and 3 to 10 to obtain pre-treated textile waste suitable to be submitted to an extrusion step, ii) contacting the pre-treated textile waste obtained at step i) with a depolymerizing agent, in conditions suitable for depolymerizing said at least one target polymer, to obtain a mixture comprising oligomers and/or monomers of said at least one target polymer, and iii) recovering and optionally purifying the oligomers and/or monomers obtained at step ii).

12. The process according to claim 11, wherein the depolymerizing agent is selected from chemical and biological depolymerizing agents, preferably enzymes, more preferably enzymes able to degrade the at least one target polymer comprised in the pre-treated waste obtained at step i).

13. The process according to claim 11 or claim 12, wherein each depolymerizing agent is a biological depolymerizing agent which is a depolymerase, preferably a depolymerase selected from the group consisting of a cutinase, a lipase, a protease, a carboxylesterase and an esterase, more preferably a cutinase, and wherein at least two different depolymerizing agents are preferably used at step ii).

14. The process according to any one of claims 11 to 13, comprising: i) submitting textile waste comprising at least one target polymer to a pre-treatment process according to any one of claims 1 and 3 to 10 to obtain pre-treated textile waste, ii) submitting the pre-treated textile waste obtained at step i) to an extrusion step, preferably an extrusion-foaming step, to obtained an extruded pre-treated textile waste, iii) contacting the extruded pre-treated textile waste obtained at step ii) with a depolymerizing agent, in conditions suitable for depolymerizing said at least one target polymer, to obtain a mixture comprising oligomers and/or monomers of said at least one target polymer, and iv) recovering and optionally purifying the oligomers and/or monomers obtained at step iii).

15. The process according to any one of claims 11 to 14, wherein the at least one target polymer comprised in the textile waste is polyethylene terephthalate (PET), and wherein the depolymerizing agent is an enzyme able to degrade polyethylene terephthalate (PET).