Method for degrading plastic products

Abstract

The present invention relates to a method for degrading a plastic product comprising at least one polymer, said method comprising subjecting the plastic product to a spinning step to obtain fibers of said plastic product; and depolymerizing at least one polymer of said fibers.

Description

Technical Field

[0001] The present invention relates to a method for degrading plastic products. The method of the present invention comprises in particular the following steps: spinning the plastic product and then depolymerizing at least one polymer of the spun plastic product. The method of the present invention is particularly suitable for degrading plastic products comprising polyesters and / or polyamides, preferably polyethylene terephthalate and / or polylactic acid. The present invention also relates to a method for producing monomers and / or oligomers from the spun plastic product. Background Art

[0002] Plastics are cheap and durable materials that can be used to make a variety of products with a wide range of applications (food packaging, textiles, etc.). Therefore, the production of plastics has increased dramatically over the past few decades. In addition, most of them are used for disposable, disposable applications, such as packaging, agricultural films, disposable consumer goods, or short-lived products that are discarded within one year after manufacturing. Due to the durability of the polymers involved, a large amount of plastics are accumulated in landfills and natural habitats around the world, resulting in more and more environmental problems. For example, in recent years, polyethylene terephthalate (PET)--a kind of aromatic polyester produced from terephthalic acid and ethylene glycol--has been widely used in the manufacture of several products for human consumption, such as food and beverage packaging (e.g., bottles, convenient soft drinks, bags for food) or textiles, fabrics, blankets, carpets, etc.

[0003] Different solutions, from plastic degradation to plastic recycling, have been studied to reduce the environmental and economic impacts associated with the accumulation of plastic waste, including recycling technologies and the production of energy from such plastics. Mechanical recycling technology remains the most commonly used, but it faces several drawbacks. In fact, it requires extensive and expensive sorting and leads to downgrading applications due to the loss of molecular weight during the process and the uncontrolled presence of additives in the recycled products. The actual recycling technologies are also expensive, so recycled plastic products are usually not competitive compared to virgin plastics.

[0004] Recently, innovative processes for enzymatic recovery of plastic products have been developed and described (e.g., WO 2014 / 079844, WO 2015 / 097104, WO 2015 / 173265, and WO 2017 / 198786). In contrast to conventional recovery techniques, this enzymatic depolymerization process allows recovery of the chemical components (i.e., monomers and / or oligomers) of the polymer. The resulting monomers / oligomers can be recovered and used to re-manufacture plastic articles, so these processes lead to unlimited recycling of plastics. These processes are particularly suitable for recovering terephthalic acid and ethylene glycol from plastic products comprising PET.

[0005] However, there is always a need for processes with improved degradation rates. Summary of the invention

[0006] By improving the process of degrading plastic products, the inventors have shown that the degradation step can be improved by increasing the contact area between the plastic product and the degradation agent. The inventors have therefore developed a method in which the surface area of ​​the plastic is increased by converting the plastic product into fibers, which are then subjected to a degradation step. More specifically, the inventors propose spinning the plastic product, which is then subjected to depolymerization. The method of the present invention is particularly suitable for degrading plastic products comprising polyethylene terephthalate.

[0007] In this regard, an object of the present invention is to provide a method for degrading a plastic product comprising at least one polymer, said method comprising the steps of: subjecting the plastic product to a spinning step to obtain fibers of said plastic product; and depolymerizing at least one polymer of said fibers. Preferably, the spinning step is a melt spinning step, which is carried out with the plastic product in a partially or completely molten state, at a temperature above the crystallization temperature (Tc) of at least one polymer of the plastic product, preferably at or above the melting temperature (Tm) of said polymer.

[0008] Advantageously, the cooling of the obtained fibers is carried out at a temperature below the crystallization temperature (Tc) of at least one of the polymers of interest for the plastic product, preferably below the glass transition temperature (Tg) of said polymer.

[0009] In one embodiment, the method is carried out on rigid or flexible plastic waste, including plastic bottles, plastic pallets, plastic bags and plastic packaging, soft and / or hard plastics, and / or from crystalline plastic fibers, in particular from plastic fibers comprising thermoplastic polymers.

[0010] Another object of the present invention is to provide a method for degrading a plastic product containing PET, the method comprising the following steps:

[0011] a. subjecting the plastic product to melt spinning at a temperature above 170°C, preferably at or above 230°C, to obtain fibers from the plastic product, wherein cooling of the resulting fibers is carried out at a temperature below 100°C, preferably below 90°C;

[0012] b. depolymerizing the PET in the fibers, preferably by contacting the fibers with a depolymerizing enzyme such as a cutinase; and optionally

[0013] c. Recovering and optionally purifying the oligomers and / or monomers produced by the depolymerization of the PET.

[0014] Another object of the present invention is to provide a method for producing monomers and / or oligomers and / or degradation products from a plastic product comprising at least one polymer, preferably PET, said method comprising subjecting the plastic product to a spinning step and a depolymerization step, preferably comprising exposing the plastic product to a depolymerase, preferably a cutinase. DETAILED DESCRIPTION

[0015] definition

[0016] The present disclosure will be better understood by reference to the following definitions.

[0017] In the context of the present invention, the terms "plastic article" or "plastic product" are used interchangeably and refer to any article or product comprising at least one polymer, such as plastic sheets, trays, tubes, rods, profiles, shapes, bulk blocks, fibers, etc. Preferably, the plastic article is a manufactured product, such as rigid or flexible packaging (bottles, trays, cups, etc.), agricultural films, bags and sacks, disposable items, etc., carpet waste, fabrics, textiles, etc. More preferably, the plastic article refers to plastic or textile waste. Preferably, the plastic article comprises a mixture of semi-crystalline and / or amorphous polymers. The plastic article may also contain additional substances or additives, such as plasticizers, minerals, organic fillers, dyes, etc.

[0018] "Polymer" refers to a compound or mixture of compounds whose structure consists of multiple repeating units (i.e., "monomers") connected by covalent chemical bonds. In the context of the present invention, the term "polymer" refers to such compounds used in plastic product compositions. For example, synthetic polymers include polymers derived from petroleum, such as polyolefins, aliphatic or aromatic polyesters, polyamides, polyurethanes, and polyvinyl chloride. In the context of the present invention, polymer refers to thermoplastic polymers, i.e., polymers that become moldable above a certain temperature and solidify when cooled.

[0019] The term "depolymerization" in relation to a polymer or a plastic article containing a polymer refers to a process of depolymerizing and / or degrading a polymer or at least one polymer of the plastic article into smaller molecules, such as monomers and / or oligomers and / or any degradation products.

[0020] According to the present invention, "oligomer" refers to a molecule containing 2 to about 20 monomer units. For example, oligomers recovered from PET include methyl-2-hydroxyethyl terephthalate (MHET) and / or bis(2-hydroxyethyl) terephthalate (BHET) and / or 1-(2-hydroxyethyl)-4-methyl terephthalate (HEMT) and / or dimethyl terephthalate (DMT). As another example, oligomers of lactic acid can be recovered from PLA.

[0021] In the context of the present invention, the term "polyester" refers to a polymer containing ester functional groups in its backbone. The ester functional group is characterized by a carbon bonded to three other atoms: single bonded to carbon, double bonded to oxygen, and single bonded to oxygen. The single bonded oxygen is bonded to another carbon. Depending on the composition of its backbone, polyesters can be aliphatic, aromatic, or semi-aromatic. Polyesters can be homopolymers or copolymers. For example, polyethylene terephthalate is a semi-aromatic copolymer composed of two monomers: terephthalic acid and ethylene glycol.

[0022] In the context of the present invention, "crystalline polymer" or "semi-crystalline polymer" refers to a partially crystalline polymer in which crystalline regions and amorphous regions coexist. The crystallinity of a semi-crystalline polymer can be estimated by different analytical methods, typically in the range of 10% to 90%. For example, differential scanning calorimetry (DSC) or X-ray diffraction can be used to determine the crystallinity of a polymer. Other techniques are also suitable for estimating the crystallinity of polymers with lower reliability, such as X-ray scattering (XS) (including small-angle and wide-angle XS) and infrared spectroscopy. In the present disclosure, the crystallinity has been measured using DSC. More specifically, the DSC measurement is performed as follows: a small amount of sample (a few milligrams) is heated at a constant heating rate from ambient temperature or below ambient temperature to a high temperature above the melting temperature (Tm) of the polyester. Heat flow data is collected and plotted against temperature. The crystallinity Xc (%) is calculated as follows:

[0023]

[0024] in

[0025] -ΔH f is the melting enthalpy, which can be determined by integrating the endothermic melting peak,

[0026] -ΔH cc is the cold crystallization enthalpy, determined by integrating the exothermic cold crystallization peak,

[0027] -w t is the weight fraction of polyester in the plastic, and

[0028] -ΔH f,100％ is the melting enthalpy of a fully crystalline polymer and can be found in the literature. For example, ΔH for PET is f,100％ From the literature, it is 125.5 J / g (Polymer Data Handbook, 2nd Edition, edited by James E. Mark, OXFORD, 2009). According to the literature, the ΔH of PLA is f,100％Equal to 93J / g (Fisher EW, Sterzel HJ, Wegner G., Investigation of the structure of solution grown crystals of lactide copolymers by means of chemical reactions, Kolloid Zeitschrift&Zeitschrift fur Polymere, 1973, 251, p980-990).

[0029] The error tolerance for crystallinity is about 10%. Thus, a crystallinity of about 25% corresponds to a crystallinity between 22.5% and 27.5%.

[0030] In the context of the present invention, "Tg", "Tc" and "Tm" refer to the glass transition temperature, crystallization temperature and melting temperature of a polymer, respectively. Such temperatures can be estimated by different analytical methods. For example, differential scanning calorimetry (DSC) or differential thermal analysis (DTA) can be used to determine the Tg, Tc and Tm of a polymer. In the present disclosure, the Tg, Tc and Tm of the disclosed polymers correspond to the temperatures measured by DSC.

[0031] Spinning steps

[0032] The inventors have shown that the depolymerization rate of polymers, in particular polyesters and / or polyamides and / or polyolefins, contained in a plastic product can be increased by converting the plastic product into fibers before one or more polymers are subjected to depolymerization. Converting the plastic product into fibers (solid and / or hollow fibers, including filaments and / or nonwovens) allows increasing the contact surface (i.e. contact area) between the plastic product (and thus the polymer) and the depolymerization agent. In other words, by increasing the contact area between the plastic product and the depolymerization agent, the depolymerization rate can be increased and / or the amount of depolymerization agent can be reduced and / or the time required for the degradation of the plastic product can be reduced compared to the same plastic product that has not been spun.

[0033] As used herein, "spinning" refers to a forming process that results in the production of polymer fibers. There are many types of spinning, including wet spinning, dry spinning (by solvent dissolution), dry-jet wet spinning, melt spinning, gel spinning, and electrospinning. The spinning process requires a spinneret.

[0034] As used herein, the term "spinneret" refers to a specific type of die that is primarily used for fiber manufacturing. It is typically a small metal plate with fine holes, through which a spinning solution (a stream of viscous or slurry polymers, prepared by melting or chemically dissolving raw materials) is forced and / or pulled to form fibers by, for example, pumping. They emerge from the spinneret in the form of long fibers, which are then solidified by condensation, evaporation, or cooling. The size and shape of the spinneret holes determine the cross-sectional shape of the fiber. The holes of the spinneret can be in various shapes: circular, flat, trilobal, Y-shaped, octyllobal, etc. Depending on the type of spinneret used, solid or hollow fibers can be formed. For example, nonwovens or filaments can be formed.

[0035] The present invention relates in particular to a method for degrading plastic products comprising at least one thermoplastic polymer.

[0036] In a specific embodiment, the spinning step is a melt spinning step implemented with plastics in a partially or completely molten state. "Melt spinning" is generally used for meltable polymers (thermoplastic polymers, such as polyamides, polyesters and / or polyolefins). Generally speaking, the molten plastic product is forced through the holes of a spinneret, and when cooled by a cooling fluid such as an ambient flow of relatively cold air or other inert gases, the resulting molten fibers solidify and harden. In a specific embodiment, the plastic product is heated in an extruder to be in a partially or completely molten state.

[0037] In a specific embodiment, the molten plastic is extruded through a spinneret at a temperature above the crystallization temperature (Tc) of the target polymer of the plastic product (i.e., the polymer intended to be degraded or depolymerized) to form fibers. Preferably, the plastic product is subjected to a temperature at or above the melting temperature (Tm) of the target polymer of the plastic product. Even more preferably, the plastic product is subjected to a temperature between Tm+5°C and Tm+25°C of the target polymer, preferably between Tm+10°C and Tm+25°C, more preferably between Tm+15°C and Tm+25°C, such as Tm+20°C of the target polymer. In another embodiment, the plastic product is subjected to a temperature between Tm+25°C and Tm+50°C of the target polymer. In another embodiment, the plastic product is subjected to a temperature corresponding to Tm+50°C or higher of the target polymer.

[0038] According to one embodiment of the invention, the plastic product comprises several different polymers. In particular, the plastic product comprises at least 51% by weight of the target polymer. In this case, the plastic product is advantageously subjected to a temperature at or above the Tc, or to a temperature at or above the Tm of the target polymer. Alternatively, the plastic product is subjected to a temperature at or above the highest Tc or Tm of the polymers contained in the plastic product.

[0039] In a specific embodiment, the plastic product comprises PET and the melt spinning step comprises subjecting the plastic product to a temperature above 170° C., preferably at or above 230° C., more preferably between 250° C. and 300° C. Even more preferably, the plastic product comprising PET is subjected to a temperature between 260° C. and 280° C. In another embodiment, the plastic product comprising PET is subjected to a temperature at or above 300° C., preferably between 300° C. and 320° C.

[0040] In another specific embodiment, the plastic product comprises PLA and the melt spinning step comprises subjecting the plastic product to a temperature above 110° C., more preferably at or above 145° C. In a specific embodiment, the plastic product comprises PLLA and the melt spinning step comprises subjecting the plastic product to a temperature at or above 170° C. In another embodiment, the plastic product comprises stereocomplex PLA and the melt spinning step comprises subjecting the plastic product to a temperature at or above 230° C.

[0041] According to the present invention, preferably use extruder and spinneret to implement melt spinning process. Advantageously, extruder is selected from single screw extruder, multi-screw extruder of co-rotating or counter-rotating design, planetary roller extruder, dispersed kneader, reciprocating single screw extruder (co-kneader), mini extruder or co-extruder. Preferably, melt spinning process also comprises using melt pump, filter and distributor system. In a specific embodiment, molten or partially molten plastic product is filtered before spinning step.

[0042] Advantageously, the spinneret is selected from spinnerets for nonwoven products or filaments. In a specific embodiment, the melt spinning step is performed using a spunbond spinneret or a meltblown spinneret to produce a spunbond or meltblown nonwoven fiber.

[0043] In a specific embodiment, the spun plastic product is formed into a nonwoven fiber, which exhibits a porosity higher than 30%, preferably higher than 40%. In the context of the present invention, the porosity of the nonwoven fiber is calculated according to the following equation:

[0044] Porosity (%) = 1-(Nonwoven fabric weight [g / m 2 ]) / (material density*thickness[μm])

[0045] The nonwoven weight corresponds to the weight ratio of the filaments on its surface (in g / m2), and the material density corresponds to the density of the plastic product before spinning. The thickness is determined according to standard NWSP 120.6.

[0046] In another specific embodiment, the melt spinning step is carried out in an extruder comprising a spinneret for filaments. In particular, such filaments are selected from monofilaments or multifilaments. In a preferred embodiment, the spinneret produces filaments with a diameter below 800 μm.

[0047] In one embodiment, melt spinning is performed using a coextruder. The use of a coextruder can be used to produce bicomponent fibers, that is, produced by spinning two different plastic products.

[0048] Cooling Steps

[0049] According to one embodiment, the fiber (i.e. the spun plastic product) is cooled when the fiber comes out of the spinneret. In fact, as disclosed above, melt spinning is advantageously carried out with at least partially molten plastic forced through the spinneret. The obtained fiber is then subjected to a sufficiently cold temperature to solidify the fiber. Classically, the cooling of the fiber can be carried out with any cooling fluid, including cooling air and cooling liquid, preferably cooling air.

[0050] In a specific embodiment, the fiber is cooled less than 30 seconds after coming out of the spinneret, more preferably less than 20 seconds, and even more preferably less than 10 seconds. Preferably, the fiber is cooled immediately after coming out of the spinneret (e.g., for filament production). For melt-blown production, the resulting fiber is passed through a high-speed hot air stream and then collected on a rotating drum or forming belt at ambient temperature to cool the fiber and generate a nonwoven web.

[0051] Advantageously, cooling is carried out by subjecting the fibres to a temperature below the Tc of the polymer of interest, preferably below the glass temperature (Tg) of said polymer.

[0052] This rapid cooling after the heating phase allows amorphization of at least one polymer in the fiber. Amorphization occurs during the heating of the plastic product, and rapid cooling at a temperature below Tc and / or Tg allows fixing the heated polymer in the amorphous state. Amorphization advantageously increases the depolymerization capacity of said polymer.

[0053] In a specific embodiment, during the melt spinning step, the target polymer of the plastic product is amorphized by heating the plastic product to a temperature above Tc, preferably above Tm of said polymer, at which point the fiber is formed and the obtained fiber is rapidly cooled at a temperature below Tc and / or Tg of said polymer.

[0054] As used herein, the terms "amorphization" and "amorphization" in relation to polymers refer to a decrease in the crystallinity of a given polymer compared to its crystallinity before amorphization. Preferably, amorphization allows the crystallinity of the target polymer to be reduced by at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 60%, 70%, 80%, or 90% compared to before amorphization. Advantageously, amorphization results in a polymer having a crystallinity of at most 30%, preferably at most 25%, more preferably at most 20%, even more preferably at most 15%. Alternatively, amorphization allows the crystallinity of a polymer to be maintained at less than 30%, preferably less than 25%, more preferably less than 20%, even more preferably less than 15%. Amorphization thus improves the ability of the polymer to be depolymerized by biological agents.

[0055] Those skilled in the art can adjust the temperature of heating and cooling according to the target polymer. Generally speaking, the plastic product can be subjected to heat treatment and optional shear stress for a period of time sufficient to obtain the amorphization of the target polymer. For example, depending on the temperature and / or the plastic product, such a time period can be included between 1 second and several minutes. In a preferred embodiment, the melt spinning step is implemented with such a plastic product, which has been subjected to shear stress and a temperature higher than the Tc of the target polymer of the plastic product, preferably at or higher than the Tm of the polymer. Preferably, heating and shear stress are simultaneously carried out to increase amorphization.

[0056] In a particular embodiment, cooling is performed by subjecting the fiber to a temperature below the Tc of the target polymer of the plastic product, preferably below the Tg of the polymer. Subjecting to a temperature below the Tc of the target polymer of the plastic product is particularly suitable for, for example, PBAT or any polymer with a Tg below 20°C. In another embodiment, cooling is performed by subjecting the fiber to a temperature at least 20°C, preferably at least 30°C, 40°C, 50°C below the Tc of the target polymer. In one embodiment, cooling is performed by subjecting the fiber to room temperature (i.e., 25°C + / - 5°C). In another embodiment, cooling is performed by subjecting the fiber to a temperature of about 20°C or about 10°C.

[0057] Advantageously, the cooling can be carried out by placing the fiber in ambient air. For example, the fiber is placed in ambient air, the temperature of which is between 15°C and 30°C, preferably between 20°C and 25°C. Alternatively, the fiber is placed in cold air at a temperature below 14°C, preferably below 10°C or below 5°C. In particular, the method applies an air cooler. Alternatively, the fiber is placed in air, the temperature of which is below the Tc of the target polymer. More generally, any method suitable for rapidly reducing the temperature of the fiber (e.g., a cooling liquid) can be used. Alternatively, the cooling can be carried out by immersing the fiber in a liquid at a cooling temperature immediately after forming.

[0058] Generally speaking, fiber stands cooling temperature and reaches enough time periods to reduce their temperature.For example, according to output, the temperature of the fiber discharged from spinneret and / or cooling temperature and / or the diameter of fiber, such time period can be included in less than 1 second and several minutes.Especially, fiber stands cooling temperature and reaches less than 1 minute, preferably less than 30 seconds, more preferably less than 20 seconds, even more preferably less than 10 seconds, less than 7 seconds, less than 5 seconds, about 1 second.Those skilled in the art will easily adapt the duration of cooling and air velocity to obtain solid filaments and / or nonwoven.

[0059] It is therefore an object of the present invention to provide a method for degrading a plastic product comprising at least one polymer, said method comprising the following steps:

[0060] a. subjecting the plastic product to melt spinning to form fibers by heating the plastic product at a temperature above the crystallization temperature (Tc), preferably above the melting temperature (Tm) of the target polymer of the plastic product; wherein cooling of the resulting fibers is carried out at a temperature below the Tc of the target polymer, preferably below the Tg of the polymer, and

[0061] b. Depolymerizing at least the target polymer.

[0062] Advantageously, melt spinning is performed using an extruder and a spinneret, and the resulting fibers are subjected to ambient and / or cold air.

[0063] In a specific embodiment, the plastic product comprises PET, the melt spinning step is carried out using an extruder at a temperature above 170° C., preferably at or above 230° C., wherein cooling of the resulting fibers is carried out at a temperature below 100° C., preferably below 90° C. Alternatively, cooling of the fibers is performed by subjecting the fibers to a temperature below 50° C.

[0064] In a specific embodiment, after the melt spinning step, the target polymer in the fiber is at least partially amorphous and exhibits a crystallinity of at most 30%, preferably at most 25%, more preferably at most 20% after cooling. In particular, the polymer is PET, and the PET in the fiber exhibits a crystallinity of at most 30%, preferably at most 25%, more preferably at most 20%.

[0065] In particular, an object of the present invention is to provide a method for degrading a plastic product comprising at least PET, said method comprising the following steps:

[0066] a. subjecting the plastic product to melt spinning at a temperature of greater than 170°C, preferably greater than 185°C, more preferably greater than 200°C, even more preferably greater than or equal to 230°C, wherein cooling of the resulting fiber is carried out at a temperature of less than 100°C, preferably less than 90°C;

[0067] b. Depolymerizing the PET of the fibers.

[0068] Advantageously, the melt spinning step is carried out at a temperature above 240°C, 245°C, 250°C, 255°C, 260°C, 265°C and cooling is carried out in less than 30 seconds after melt spinning, preferably immediately thereafter.

[0069] Preferably, the depolymerization step is performed using an esterase, more preferably a cutinase.

[0070] In a particular embodiment, the plastic product is foamed before being formed into fibers. For example, the plastic product is foamed in an extruder before being forced through a spinneret. Foaming can be performed using a physical foaming agent, preferably selected from gases, more preferably selected from nitrogen, carbon dioxide, methane, helium, neon, argon, xenon, hydrogen or mixtures thereof, and / or a chemical foaming agent, preferably selected from citric acid, carbonates or mixtures thereof.

[0071] Therefore, another object of the present invention is to provide a method for degrading a plastic product comprising at least one polymer, said method comprising the following steps:

[0072] a. by foaming and melt-spinning the plastic product using an extruder including a spinneret to form a foamed fiber, wherein the extrusion is performed at a temperature higher than the crystallization temperature (Tc) of the target polymer of the plastic product, preferably higher than the melting temperature (Tm) of the polymer; and wherein the cooling of the foamed fiber is performed at a temperature lower than the Tc of the target polymer, preferably lower than the Tg of the polymer

[0073] b. Depolymerizing the target polymer of the fiber.

[0074] Advantageously, foaming is performed by subjecting the plastic product to a chemical foaming agent and / or cooling the fibers immediately after melt spinning, preferably by subjecting to ambient and / or cold air.

[0075] Depolymerization step

[0076] According to the invention, the degradation process comprises a step of depolymerizing at least one polymer of the spun plastic product, ie the fiber. According to a preferred embodiment, the depolymerization step is directed to at least one polymer that has previously been amorphized.

[0077] In a particular embodiment, the spun plastic product is cut into smaller pieces prior to the depolymerization step.

[0078] In one embodiment, the depolymerization step comprises contacting the spun plastic product with a depolymerization agent, ie a chemical and / or biological agent. In one embodiment, the depolymerization step is carried out in a liquid medium comprising a depolymerization agent.

[0079] In another specific embodiment, the plastic product is contacted with a depolymerizing agent before the depolymerization step. For example, after the spinning step and / or the cooling step, the fiber is immersed in a liquid containing a depolymerizing agent. In particular, the fiber can be contacted with a depolymerizing agent during the cooling step (for example, the fiber is immersed in a cooling liquid containing a depolymerizing agent and / or the depolymerizing agent is sprayed on the fiber during cooling with cold and / or ambient air). Alternatively, by immersing the cooled fiber in a liquid containing a depolymerizing agent, the fiber can be contacted with a depolymerizing agent after the air cooling step. If necessary, the fiber can be dried before the depolymerization step. The depolymerization step can be carried out later by immersing the fiber in a liquid, which preferably does not contain a depolymerizing agent. Alternatively, the depolymerization step is implemented later by placing the spun plastic product under composting conditions. In particular, the spun plastic product is subjected to industrial composting conditions with a temperature higher than 50°C, and / or a household composting condition with a temperature between 15°C and 35°C. Alternatively, the depolymerization step is implemented later by subjecting the spun plastic product to a stimulus that can activate the depolymerizing agent. For example, the depolymerizing agent is a degrading enzyme and the stimulus is a specific temperature and / or humidity rate.

[0080] It is therefore an object of the present invention to provide a method for degrading a plastic product comprising at least one polymer, said method comprising the following steps:

[0081] a. melt spinning the plastic product to produce fibers of the plastic, wherein the melt spinning step is carried out at a temperature higher than the crystallization temperature (Tc) of the target polymer of the plastic product, preferably higher than the melting temperature (Tm) of the polymer; and cooling of the spun plastic product is carried out by contacting the fiber with air at a temperature lower than the Tc of the target polymer, preferably lower than the Tg of the polymer.

[0082] b. contacting the cooled fibers with a liquid containing a depolymerizing agent; and

[0083] c. At least partially depolymerizing the target polymer by contacting the fibers with a liquid advantageously free of a depolymerizing agent.

[0084] In a specific embodiment, the depolymerizing agent is a biological agent or comprises a biological agent. In particular, the biological agent is a depolymerizing enzyme (i.e., an enzyme). Preferably, the depolymerizing enzyme is capable of degrading at least one polymer of the plastic product, preferably at least a polymer that has previously been amorphized.

[0085] The depolymerase is advantageously selected from the group consisting of cutinases, lipases, proteases, carboxylesterases, p-nitrobenzylesterases, esterases, scl-PHA depolymerases, mcl-PHA depolymerases, PHB depolymerases, amidases, aryl-acylamidases (EC 3.5.1.13), oligomer hydrolases, such as 6-aminohexanoic acid cyclic dimer hydrolases (EC 3.5.2.12), 6-aminohexanoic acid dimer hydrolases (EC 3.5.1.46), 6-aminohexanoic acid-oligomer hydrolases (EC 3.5.1.B17), oxidases, peroxidases, laccases (EC 1.10.3.2), oxygenases, lipoxygenases, monooxygenases or lignin decomposing enzymes. In a particular embodiment, the plastic product is contacted with at least two different depolymerases.

[0086] In a specific embodiment, the plastic product comprises PET, and the depolymerase is an esterase. In particular, the depolymerase is a cutinase, preferably a cutinase produced by a microorganism selected from warm bifidobacteria, salt-tolerant thermophilic split spore bacteria, brown thermophilic split spore bacteria, bifidobacteria, bacillus subtilis, pea root rot Fusarium, Humicola, Rhodococcus, Pseudomonas mendocina and Thielavia terrestris, or any functional variant thereof. In another embodiment, the cutinase is selected from a metagenomic library, such as the LC-cutinase described in Sulaiman et al., 2012 or the esterase described in EP3517608, or any functional variant thereof, including the depolymerases listed in WO 2018 / 011284 or WO 2018 / 011281. In another specific embodiment, the depolymerase is a lipase, preferably produced by Ideon bacteria. In another specific embodiment, the depolymerase is a cutinase produced by Humicola insolens, such as A0A075B5G4 mentioned 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.

[0087] In a specific embodiment, the plastic product comprises PLLA, and the depolymerizing enzyme is a protease, preferably produced by a microorganism selected from Amycolatopsis, Amycolatopsis orientalis, Candida albicans from linberi (proteinase K), Actinomyces dura, Leysella LP175, Thermus yunnanensis, or any commercial enzyme known for degrading PLA, such as Or any functional variant thereof, including the depolymerases listed in WO 2016 / 062695, WO 2018 / 109183 or WO 2019 / 122308.

[0088] In another specific embodiment, the plastic product comprises PDLA, and the depolymerase is an esterase, preferably a cutinase or a lipase, more preferably selected from CLE of Cryptococcus, lipase PS of Burkholderia cepacia, Bacillus amyloliquefaciens TB-13, Candida antarctica, Rhizomucor, Saccharomyces viridis, Cryptococcus yeast or any functional variant thereof.

[0089] In another specific embodiment, the plastic product comprises PA and the depolymerase is selected from amidase, aryl-acylamidase (EC 3.5.1.13), oligomer hydrolase, such as 6-aminohexanoic acid cyclic dimer hydrolase (EC 3.5.2.12), 6-aminohexanoic acid dimer hydrolase (EC 3.5.1.46), 6-aminohexanoic acid-oligomer hydrolase (EC 3.5.1.B17).

[0090] In another particular embodiment, the plastic product comprises a polyolefin and the depolymerase is an oxidase, preferably selected from the group consisting of a laccase, a peroxidase, an oxygenase, a lipoxygenase, a monooxygenase or a ligninolytic enzyme.

[0091] In another embodiment, the depolymerizing agent is a microorganism that expresses and excretes a depolymerase. The microorganism can synthesize the depolymerase naturally, or it can be a recombinant microorganism in which a recombinant nucleotide sequence encoding the depolymerase is inserted using, for example, a vector. Specific embodiments of the depolymerization step can be found in WO 2017 / 198786.

[0092] According to the invention, several microorganisms and / or purified enzymes and / or synthetases can be used together or sequentially to depolymerize different polymers contained in the same plastic product or in different plastic products simultaneously subjected to the degradation process of the invention.

[0093] The time required to depolymerize at least one polymer of the plastic product may vary depending on the plastic product and / or the target polymer (e.g., the nature and origin of the plastic product, its composition, shape, molecular weight, etc.), the type and amount of microorganisms / enzymes used, and various process parameters (i.e., temperature, pH, additional reagents, etc.). A person skilled in the art can easily adapt the process parameters to the plastic product and / or the depolymerizing enzyme.

[0094] In a specific embodiment, the plastic product comprises PET, and the depolymerization step is carried out by contacting the plastic product with a biodepolymerizing agent 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. and 75° C., even more preferably between 60° C. and 75° C. Furthermore, the depolymerization step is preferably carried out at a pH of 5-11, preferably 7-9, more preferably 7-8.5, even more preferably 7-8. Alternatively, the depolymerization step may be carried out under industrial and / or composting conditions.

[0095] In a specific embodiment, the plastic product comprises PLA, and the depolymerization step is carried out by contacting the plastic product with a biodepolymerizing agent 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 between 40°C and 50°C, even more preferably 45°C. Furthermore, the depolymerization step is preferably carried out 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 specific embodiment, the depolymerization step may be carried out at a pH between 7 and 8. Alternatively, the depolymerization step may be carried out under industrial and / or composting conditions.

[0096] In another specific embodiment, the depolymerization agent is a chemical agent or comprises a chemical agent. In particular, the chemical agent is a catalyst selected from a metal catalyst or stabilizer and a non-toxic hydrosilane (PMHS, TMDS), such as commercially available B(C6F5)3 and [Ph3C+, B(C6F5)4-] catalyst. Specifically, the catalyst is selected from alkoxides, carbonates, acetates, hydroxides, alkali metal oxides, alkaline earth metals, calcium oxide, calcium hydroxide, calcium carbonate, sodium carbonate, iron oxide, zinc acetate, zeolites. In some embodiments, the catalyst used in the depolymerization process of the present invention includes at least one of the following: 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. Specifically, the catalyst includes at least one of the following: germanium dioxide, cobalt acetate, titanium tetrachloride, titanium phosphate, titanium tetrabutoxide, titanium tetraisopropoxide, titanium tetra-n-propoxide, titanium tetraethoxide, titanium tetramethoxide, titanium tetra(acetylacetonate) complex, titanium tetra(2,4-hexanedione) complex, titanium tetra(3,5-heptanedione) complex, dimethoxybis(acetylacetonate) titanium complex, diethoxybis(acetylacetonate) titanium complex, diisopropoxybis(acetylacetonate) titanium complex, di-n-propoxybis(acetylacetonate) titanium complex, dibutoxybis(acetylacetonate) titanium complex, dihydroxydiglycolic acid titanium, dihydroxydiglycolic acid titanium, dihydroxydilactate titanium, dihydroxydiol Titanium bis(2-hydroxypropionate), titanium lactate, titanium octanediol, titanium dimethoxybistriethanolamine, titanium diethoxybistriethanolamine, titanium dibutoxybistriethanolamine, hexamethyldititanate, hexaethyldititanate, hexapropyldititanate, hexabutyldititanate, hexaphenyldititanate, octamethyltrititanate, octaethyltrititanate, octapropyltrititanate, octabutyltrititanate, octaphenyltrititanate, hexaalkoxydititanate, zinc acetate, manganese acetate, methyl silicate, zinc chloride, lead acetate, sodium carbonate, sodium bicarbonate, acetic acid, sodium sulfate, potassium sulfate, zeolite, 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 nanoparticles. The chemical agent can be selected from any catalyst known to those skilled in the art that has the ability to degrade and / or depolymerize the target polymer.

[0097] Alternatively, the chemical agent is an acid or base catalyst capable of breaking polymer bonds, especially ester bonds. In particular, the chemical agent involved in the cleavage of ester bonds is a mixture of a hydroxide and an alcohol that can dissolve the hydroxide. The hydroxide is selected from alkali metal hydroxides, alkaline earth metal hydroxides and ammonium hydroxide, preferably selected from sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, magnesium hydroxide, ammonium hydroxide, tetraalkylammonium hydroxide, and the alcohol is selected from linear, branched, cyclic alcohols or combinations thereof, preferably selected from linear C1-C4 alcohols of methanol, ethanol, propanol, butanol.

[0098] In one embodiment, the chemical agent is a mixture of a non-polar solvent (i.e., a swelling agent) capable of swelling the polymer and an agent capable of breaking or hydrolyzing ester bonds, wherein the swelling agent is preferably a chlorinated solvent selected from dichloromethane, dichloroethane, tetrachloroethane, chloroform, tetrachloromethane and trichloroethane. In another embodiment, the chemical agent is an acid selected from ethylene glycol, hydrochloric acid, sulfuric acid or a Lewis acid.

[0099] Target plastic products

[0100] The inventors have developed a degradation method for degrading plastic products comprising polymers, preferably comprising thermoplastic polymers, such as polyesters and / or polyamides and / or polyolefins. The method of the present invention can be advantageously used for plastic products from plastic waste collection and / or post-industrial waste. More specifically, the method of the present invention can be used to degrade household plastic waste, including plastic bottles, plastic pallets, plastic bags and plastic packaging, soft and / or hard plastics, even contaminated by food residues, surfactants, etc. Alternatively, or in addition, the method of the present invention can be used to degrade used plastic fibers, such as fibers provided by fabrics, textiles and / or industrial waste. More specifically, the method of the present invention can be used for PET plastics and / or PET fiber waste, such as PET fibers provided by fabrics, textiles or tires. Interestingly, the method of the present invention allows the production of monomers and / or oligomers and / or any degradation products that can be further recycled and / or reprocessed.

[0101] In a particular embodiment, the plastic product is selected from rigid or flexible plastic waste, including plastic bottles, plastic pallets, plastic bags and plastic packaging, soft and / or hard plastics, i.e. from plastic waste that has not been formed into fibers, and / or from crystalline plastic fibers, in particular from crystalline plastic fibers comprising thermoplastic polymers (e.g. yarns, filaments, braids, ropes, fabrics and nonwovens).

[0102] In a particular embodiment, the method of the invention is used for the degradation of plastic products comprising at least one thermoplastic polymer, in particular one semicrystalline thermoplastic polymer.

[0103] Advantageously, the method of the invention is used to degrade plastic products comprising at least one polyester selected from the group consisting of: polyethylene terephthalate (PET); polytrimethylene terephthalate (PTT); polybutylene terephthalate (PBT); polyisosorbide terephthalate (PEIT); polylactic acid (PLA); polyhydroxyalkanoate (PHA); polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBA T), polyethylene furanoate (PEF), polycaprolactone (PCL), polyethylene adipate (PEA), polyethylene naphthalate (PEN), polycyclohexane terephthalate (PCT), polyethylene succinate (PES), poly(butylene succinate-co-butylene terephthalate) (PBST), poly(butylene succinate / terephthalate / isophthalate)-co-(lactate) (PBSTIL) and blends / mixtures of these polymers. In particular, the method of the present invention is used to degrade plastic products containing at least one aromatic polyester selected from the group consisting of polyethylene terephthalate (PET); polytrimethylene terephthalate (PTT); polybutylene terephthalate (PBT); polyisosorbide terephthalate (PEIT); polybutylene adipate terephthalate (PBAT), poly(ethylene furanoate) (PEF) and blends / mixtures of these polymers.

[0104] In a particular embodiment, the process according to the invention is used for the degradation of plastic products comprising at least one polyester, preferably at least PET or PLA.

[0105] Alternatively, the method of the present invention is used to degrade a plastic product comprising at least one polyamide selected from polyamide-6 or poly(β-caprolactam) or polycaproamide (PA6), polyamide-6,6 or poly(hexamethylene adipamide) (PA6,6), poly(11-aminoundecanamide) (PA11), polylaurolactam (PA12), poly(tetramethylene adipamide) (PA4,6), poly(pentamethylene sebacamide) (PA5,10), poly(hexamethylene azelaic acid) (PA6,9), poly(hexamethylene sebacamide) (PA6,10), poly(hexamethylene dodecanamide) (PA6,12), poly(isophthalamide) (PAMXD6), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (PA66 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (PA66 / 6I) and mixtures / mixtures of these materials.

[0106] Alternatively, the method of the present invention is used to degrade a plastic product comprising at least one polyolefin selected from the group consisting of polyethylene, polypropylene, polymethylpentene, polybutene-1, polyisobutylene, ethylene-propylene rubber, ethylene-propylene diene monomer rubber, ethylene vinyl alcohol, ethylene-carbon monoxide copolymers, and copolymers and modifications thereof.

[0107] In a specific embodiment, the plastic product comprises at least two different polymers. More generally, the plastic product to which the method of the present invention is directed may comprise different types of polymers, including synthetic polymers derived from petrochemicals such as polyamides, polyolefins or vinyl polymers, or bio-based sources such as rubber, wood or wood compounds such as lignin, cellulose or hemicellulose, and starch and its derivatives. Alternatively, the plastic product may comprise at least one polymer and additional components, such as metal compounds, mineral compounds, glass compounds, natural or synthetic fibers (such as glass fibers or carbon fibers), paper, and derivatives thereof as defined in WO 2015 / 173265.

[0108] Interestingly, the process of the invention allows the production of monomers and / or oligomers and / or degradation products which can be further recovered and / or reprocessed.

[0109] Production of monomers / oligomers / degradation products

[0110] Another object of the present invention is to provide a method for producing monomers and / or oligomers and / or any degradation products from a plastic product comprising at least one polymer, the method comprising sequentially subjecting the plastic product to melt spinning and cooling the resulting fibers, and then depolymerizing at least one target polymer in the fibers.

[0111] Another object of the present invention is to provide a method for degrading a plastic product comprising at least one polymer, wherein the plastic product has been previously spun, the polymer of the plastic product has been optionally at least partially amorphized and wherein the plastic product is contacted with a depolymerizing agent capable of degrading the polymer, preferably a biological agent, more preferably a depolymerizing enzyme. In a specific embodiment, the plastic product is depolymerized under composting conditions or under ambient conditions. In particular, the plastic product is subjected to industrial composting conditions at a temperature above 50°C, and / or domestic composting conditions at a temperature between 15°C and 35°C. In this case, the polymer of the plastic product may be degraded into water and / or carbon dioxide and / or methane by microorganisms in the compost and / or the environment.

[0112] Another object of the present invention is to provide a method for degrading a plastic product, the plastic product is selected from rigid or flexible plastic waste and / or from crystalline plastic fibers comprising at least one polymer, and wherein the plastic product has been previously spun, the method comprising a depolymerization step, wherein the plastic product is contacted with a depolymerizing agent capable of degrading the polymer, preferably a biological agent, more preferably a depolymerizing enzyme. In one embodiment, the polymer of the plastic product has undergone an amorphization step before the depolymerization step. In a specific embodiment, the method for degrading a plastic product and / or the method for producing a monomer / oligomer also includes a step of purifying the monomers and / or oligomers and / or degradation products produced by the depolymerization step. The monomers and / or oligomers and / or degradation products can be recovered sequentially or continuously. Depending on the polymer and / or the starting plastic product, a single type of monomer and / or oligomer or several different types of monomers and / or oligomers can be recovered. The recovered monomers and / or oligomers and / or degradation products can be purified using all suitable purification methods and adjusted in a repolymerizable form. In a preferred embodiment, the repolymerizable monomers and / or oligomers can then be used to synthesize polymers. A person skilled in the art can easily adapt the process parameters to the monomers / oligomers and polymers for the synthesis.

[0113] Another object of the present invention is to provide a method for recycling a plastic product selected from rigid or flexible plastic waste and / or crystalline plastic fibers and comprising at least one polymer, said method comprising subjecting said plastic product to a melt spinning step and a depolymerization step in sequence, and recovering monomers and / or oligomers of such polymer. Preferably, the depolymerizing agent is a biological agent, more preferably a depolymerizing enzyme suitable for degrading said polymer of said plastic product.

[0114] Therefore, one object of the present invention is to use a spun plastic product comprising at least one polymer to produce monomers and / or oligomers of this polymer by subjecting the spun plastic product to a depolymerization step, preferably by using a depolymerizing agent selected from biological agents, more preferably a depolymerizing enzyme.

[0115] The embodiments described above in connection with the degradation process are also applicable to the method of producing monomers / oligomers and the method of recovering plastic products and the method of recycling.

[0116] Production of biodegradable plastics

[0117] Another object of the present invention is to provide a plastic product comprising at least one polymer and incorporating at least one enzyme capable of degrading said polymer, wherein said enzyme has been incorporated into the plastic product according to the following method:

[0118] a. melt spinning said plastic product, wherein the melt spinning step is carried out at a temperature above Tc, preferably above Tm of said polymer, and wherein cooling of the resulting fiber is carried out less than 30 seconds after the melt spinning step, preferably immediately after the melt spinning step, by subjecting the fiber to cooling air at a temperature below Tc and / or Tg of said polymer

[0119] b. subjecting the resulting cooled fibers to a liquid comprising a depolymerizing agent, advantageously chosen from depolymerizing enzymes.

[0120] Other aspects and advantages of the present invention will be disclosed in the following examples, which should be considered as illustrative and not limiting the scope of the present application. These examples provide experimental data supporting the present invention and methods for implementing the present invention.

[0121] Example

[0122] Example 1 - Method for degrading a plastic product comprising PET, comprising a meltblowing spinning step Meltblown spinning steps

[0123] The filter area is 564cm 2 Colored and washed flakes from 98% PET PET bottles were extruded to obtain pellets using an Intarema 1108TE extruder with a melt filter SC_4_134_RTF. Pelletization was performed using an ECON UWP EUP 150 underwater pelletizer, the die of which contained 8 holes, each with a diameter of 2.9 mm. The extrusion temperature range used was 265°C to 285°C, and the screw speed was 155 rpm.

[0124] Some pellets have been used as control (C1), whereas other pellets have been dried at 80°C for 6 hours and used in the melt spinning step (nonwoven production).

[0125] The melt-blown spinning machine was from Hills Inc (FL, USA), as shown in Table 1.

[0126] Table 1: Characteristics of meltblown spinning machine

[0127]

[0128] The parameters used for nonwoven production by melt spinning and their main properties are summarized in Table 2.

[0129] Table 2: Parameters of the spinning step

[0130]

[0131]

[0132] *Estimated using a microscope

[0133] The fibers coming out of the spinning machine were cooled by ambient air (between 20-25° C.) The crystallinity levels of S1 and S2 were approximately 13% and 12%, respectively.

[0134] The porosity level of nonwoven products is estimated according to the following equation:

[0135] Porosity (%) = 1-(Nonwoven fabric weight [g / m 2 ]) / (material density*thickness[μm])

[0136] The nonwoven weight corresponds to the weight ratio of the filaments on its surface (in g / m2), and the material density corresponds to the density of the plastic product before spinning. The thickness is determined according to standard NWSP 120.6.

[0137] The second control (C2) was produced by micronizing some of the C1 granules using a disc mill equipped with a 500 μm screen to obtain a fine powder with a particle size distribution defined as follows: D(10)=138 μm; D(50): 326 μm; D(90): 651 μm.

[0138] A) Depolymerization in glass bottles

[0139] The depolymerization process was performed using a variant of LC-cutinase (Sulaiman et al., Appl Environ Microbiol. March 2012). This variant of the enzyme corresponding to SEQ ID N° 1 with the following mutations F208I+D203C+S248C+V170I+Y92G (LCC-ICCIG) was expressed as a recombinant protein in Trichoderma reesei.

[0140] For the depolymerization test, the spun samples S1 and S2 were cut into small pieces of approximately 2*2 cm using scissors.

[0141] For each sample (S1, S2, C1 and C2), 100 mg was weighed and introduced into a 250 ml glass bottle containing 49 ml of 0.1 M potassium phosphate buffer, pH 8. Depolymerization was initiated by incubating each sample at 60°C and 150 rpm in a Multitron pro (Infors HT, Switzerland) after adding 1 ml of a 0.1 mg / ml enzyme solution in 0.1 M potassium phosphate, pH 8.

[0142] The depolymerization rate of PET was determined by periodic sampling.The samples were analyzed by ultra high performance liquid chromatography (UHPLC) to measure the amount of terephthalic acid equivalents produced according to the methods described herein.

[0143] AT equivalent concentration was determined by chromatography (UHPLC). If necessary, the sample was diluted in 100 mM potassium phosphate buffer (pH 8). 1 mL of sample or diluted sample was mixed with 1 mL of methanol and 100 μL of 6N HCl. After homogenization and filtration through a 0.45 μm syringe filter, 20 μL of sample was injected into a UHPLC, Ultimate 3000 UHPLC system (Thermo Fisher Scientific, Waltham, MA), including a pump module, an autosampler, a column thermostated at 25 ° C, and a UV detector at 240 nm. Using a methanol gradient (30% to 90%) in 1 mM H2SO4, at 1 m / min, terephthalic acid (AT) and the resulting oligomers (MHET and BHET) were separated by an HPLC Discovery HS C18 column (150 mm x 4.6 mm, 5 μm) equipped with a precolumn (Supelco, Bellefonte, PA). AT, MHET and BHET were measured according to standard curves prepared from commercially available AT and BHET and internally synthesized MHET. AT equivalent is the sum of the measured TA and the measured TA equivalent in MHET and BHET. Based on the total amount of TA equivalent (TA+MHET+BHET) at a given time and the total amount of TA determined in the initial sample, the hydrolysis percentage of the sample was calculated. The depolymerization percentage results after 6 hours and 9 hours are shown in Table 3 below.

[0144] Table 3: Depolymerization of PET in spun plastic products comprising PET (S1 and S2) compared to plastic products which have not been subjected to a spinning process (C1 and C2 (micronized)).

[0145]

[0146]

[0147] The results show that the melt spinning step can significantly increase the percentage of PET depolymerization of the spun plastic product compared to the extruded (unspun) plastic product (C1). In addition, the results also show that the melt spinning step can increase the percentage of PET depolymerization of the spun plastic product by at least 50% compared to the extruded (unspun) and micronized plastic product (C2).

[0148] Example 2 - Method for degrading a plastic product comprising PET, comprising a multifilament production step

[0149] A) Multifilament production steps

[0150] Colored and washed flakes from PET bottles containing 95% PET were extruded using the same extruder as in Example 1-A. Some pellets from this step with a crystallinity level of 16% were used as controls (called C3). Other pellets were dried at 140°C for 4 hours before extrusion spinning.

[0151] The spinning machine used for multifilament production was a Hills Inc (FL, USA) machine equipped with a 19 mm (3 / 4") single screw extruder with a L / D ratio of 30:1 and composed of 3 zones. The melt spinning process included a melt pump and a multifilament spinneret with 36 holes, each with a diameter of 0.6 mm, a take-up roll (R1), a stretch roll (R2) and a relax roll (R3) and a winder.

[0152] The temperature for extrusion from the first extruder zone to the spinneret was 265-270-280-280-280° C. The temperature in the rolls R1-R2-R3 was set at 95-100-50° C. Other parameters are listed in Table 4 below.

[0153]

[0154] Table 4: Parameters of the multifilament melt spinning step

[0155] The multifilament was cooled by ambient air, wound on a bobbin and cut into short fibers (sample S3) of 12 mm in length. The crystallinity level was 9%.

[0156] B) Depolymerization in glass bottles

[0157] Depolymerization of samples S3 and C3 was performed under the same conditions as in Example 1-B. After 23 hours, S3 showed 80% depolymerization, while control C3 showed less than 2% depolymerization.

[0158] The results show that the melt spinning step can increase the PET depolymerization rate of the spun plastic product compared to the plastic product that has not been spun and extruded.

Claims

1. A method for degrading a plastic product comprising at least one thermoplastic polymer, the method comprising: a. subjecting the plastic product to a spinning step to obtain fibers of the plastic product; and b. depolymerizing at least one thermoplastic polymer of said fibers by contacting said fibers with a biodepolymerizing agent, said biodepolymerizing agent being a depolymerizing enzyme.

2. The method according to claim 1, wherein the spinning step is a melt spinning step, which is carried out with the plastic product in a partially or completely molten state.

3. The method according to claim 2, wherein the melt spinning step is carried out at a temperature above the crystallization temperature (Tc) of at least one thermoplastic polymer of the plastic product.

4. The method of claim 2, wherein the molten plastic product is extruded through a spinneret for a nonwoven product.

5. Process according to claim 4, wherein the fibers obtained exhibit a porosity higher than 30%.

6. The method of claim 2, wherein the molten plastic product is extruded through a spinneret for filaments, the filaments comprising monofilaments or multicomponent filaments.

7. The method according to claim 6, wherein the plastic product is selected from rigid or flexible plastic waste, including plastic bottles, plastic pallets, plastic bags and plastic packaging, soft plastics and / or hard plastics, and / or selected from crystalline plastic fibers.

8. The method of claim 2, wherein the fibers are cooled by subjecting the fibers to a temperature below a crystallization temperature (Tc) of at least one target thermoplastic polymer of the plastic product.

9. The method of claim 8, wherein the target thermoplastic polymer in the fiber exhibits a crystallinity of at most 30% after cooling.

10. The method according to claim 1 or 2, wherein the depolymerase is a depolymerase capable of degrading at least one thermoplastic polymer of the plastic product.

11. The method according to claim 1 or 2, further comprising the step of recovering and optionally purifying the oligomers and / or monomers produced by the depolymerization step.

12. The method according to claim 1, wherein the at least one thermoplastic material is a polyester selected from the group consisting of polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyisosorbide terephthalate (PEIT), polylactic acid (PLA), polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polyethylene furanoate (PEF), polycaprolactone (PCL), poly(ethylene adipate) (PEA), polybutylene succinate (PBST), polyethylene succinate (PES), poly(butylene succinate / terephthalate / isophthalate)-co-(lactic acid) (PBSTIL) and blends / mixtures of these materials.

13. A method for degrading a plastic product comprising at least PET, the method comprising the steps of: a. subjecting the plastic product to melt spinning at a temperature above 170°C to obtain fibers from the plastic product, wherein cooling of the resulting fibers is carried out at a temperature below 100°C; b. depolymerizing the PET in the fiber by contacting the fiber with a biodepolymerizing agent, the biodepolymerizing agent being a depolymerizing enzyme; and optionally c. Recovering and optionally purifying the oligomers and / or monomers resulting from the depolymerization of the PET.

14. The method according to claim 13, wherein the depolymerization step is performed by contacting the fibers with a cutinase.

15. A method for producing monomers and / or oligomers and / or degradation products from a plastic product comprising at least one thermoplastic polymer, the method comprising subjecting the plastic product to a spinning step and a depolymerization step in sequence, comprising exposing the plastic product to a depolymerizing enzyme.

16. A method for degrading a spun plastic product comprising at least one polymer, wherein the spun plastic product is contacted with a depolymerase capable of degrading at least one polymer of the plastic product, and wherein the spun plastic product is obtained from rigid or flexible plastic waste and / or from crystalline plastic fibers that are subjected to a spinning step to obtain fibers of the plastic product.

17. The method according to claim 16, wherein the polymer of the plastic product has been pre-amorphized prior to the depolymerization step.

18. A method for recycling a plastic product selected from rigid or flexible plastic waste and / or crystalline plastic fibers and comprising at least one polymer, the method comprising the step of depolymerizing at least one target polymer of the plastic product by contacting the polymer with a biodepolymerizing agent, the biodepolymerizing agent being a depolymerizing enzyme, wherein the plastic product has been pre-spun and wherein the target polymer has been optionally amorphized.

19. The method according to claim 18, wherein the method further comprises the step of recovering monomers and / or oligomers of the polymer.

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