Methods for dismantling plastic materials

Abstract

The present invention relates to a method for decomposing a plastic article comprising at least one polymer, comprising the steps of at least partially foaming the plastic article and depolymerizing at least one target polymer in the at least partially foamed plastic article, wherein the foaming step is carried out at a temperature at which the plastic article is partially or totally in a molten state.

Description

[Technical Field]

[0001] The present invention relates to a method for decomposing plastic products. The method of the present invention particularly includes a step of foaming the plastic product before depolymerizing at least one polymer of the plastic product. The method of the present invention is particularly useful for decomposing plastic products containing polyester and / or polyamide, preferably polyethylene terephthalate and / or polylactic acid. The present invention also relates to a method for producing monomers and / or oligomers from at least partially foamed plastic products. [Background technology]

[0002] background Plastics are inexpensive and durable materials that can be used to manufacture a wide range of products with applications in various fields (food packaging, textiles, etc.). As a result, the production of plastics has increased dramatically over the past few decades. Furthermore, most of them are used for disposable applications, such as packaging, agricultural films, disposable consumer goods, or short-life products that are discarded within a year of manufacture. Due to the durability of the polymers they contain, a considerable amount of plastic accumulates in landfills and natural habitats around the world, exacerbating environmental problems. For example, in recent years, polyethylene terephthalate (PET), an 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, convenience-sized soft drinks, pouches for nutritional products) or textiles, fabrics, rugs, carpets, etc.

[0003] From the decomposition of plastics to their recycling, various solutions have been studied, including recycling technologies and energy production from such plastics, to reduce the environmental and economic impacts associated with the accumulation of plastic waste. Mechanical recycling technologies remain the most widely used, but they face several drawbacks. In fact, mechanical recycling technologies require extensive and costly sorting, and the inability to control the reduction in molecular weight during processing and the presence of additives in the recycled products leads to a decline in their applications. Because actual recycling technologies are also expensive, recycled plastic products are generally not competitive compared to new plastics.

[0004] In recent years, innovative methods for enzymatic recycling of plastic products have been developed and described (e.g., WO2014 / 079844, WO2015 / 097104, WO2015 / 173265, and WO2017 / 198786). In contrast to conventional recycling technologies, such enzymatic depolymerization methods make it possible to recover the chemical components of polymers (i.e., monomers and / or oligomers). Since the obtained monomers / oligomers can be recovered and used to remanufacture plastic products, such methods result in unlimited recycling of plastics. These methods are particularly useful for recovering terephthalic acid and ethylene glycol from plastic products, including PET. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, there is always a need for methods that improve the rate of decomposition. [Means for solving the problem]

[0006] Summary of the Invention By working to improve methods for decomposing plastic products, the inventors have shown that the decomposition process can be improved by increasing the contact area between the plastic product and the decomposing agent. Thus, the inventors have developed a method for increasing the surface area of ​​the plastic before subjecting it to the decomposition process. More specifically, the inventors propose subjecting the plastic product to a foaming process before the depolymerization process. Advantageously, the foaming process allows for improved porosity of the plastic product, thereby increasing the surface area of ​​the plastic product that can come into contact with the decomposing agent, which is advantageous for the subsequent depolymerization of the polymer constituting the plastic product. The method of the present invention is particularly useful for decomposing plastic products containing polyethylene terephthalate.

[0007] In this regard, one object of the present invention is to provide a method for decomposing a plastic product containing at least one polymer, comprising the steps of at least partially foaming the plastic product and depolymerizing at least one target polymer of the at least partially foamed plastic product, wherein the foaming step is performed at a temperature in which the plastic product is partially or completely molten.

[0008] Preferably, the foaming process is carried out at a temperature higher than the crystallization temperature (Tc) of the target polymer, preferably at or above the melting temperature (Tm) of the polymer, and is performed using a physical foaming agent and / or a chemical foaming agent.

[0009] Furthermore, one object of the present invention is to provide a method further comprising the step of cooling a partially foamed plastic product within 30 seconds after the foaming process by subjecting the plastic product to a temperature below the crystallization temperature (Tc) of the polymer, preferably below the glass transition temperature (Tg) of the polymer.

[0010] Advantageously, the method of the present invention is carried out at least partially in an extruder.

[0011] In one embodiment, the depolymerization step includes contacting the plastic product with a depolymerizer selected from chemical and / or biological depolymerizers.

[0012] Furthermore, a method for decomposing plastic products including PET, a. A step of at least partially foaming the plastic product with a foaming agent, preferably a foaming agent selected from chemical foaming agents, wherein the foaming step is carried out at a temperature of over 170°C, preferably over 185°C, more preferably over 200°C, and even more preferably over 220°C, over 240°C, over 245°C, over 250°C, over 255°C, over 260°C, and over 265°C. b. A step of cooling the at least partially foamed plastic product at a temperature of less than 100°C, preferably less than 90°C, within 30 seconds after the foaming stage, c. A step of depolymerizing the PET plastic product by contacting the plastic product with a depolymerase, particularly an esterase, preferably a cutinase or lipase, more preferably a cutinase. One object of the present invention is to provide a method that includes [this].

[0013] According to one embodiment of the present invention, a plastic product is brought into contact with a depolymerase before a depolymerization step (for example, during a cooling step), and the depolymerization step includes bringing the plastic product into contact with a liquid from which the depolymerase has been removed.

[0014] According to another embodiment, the depolymerization step includes subjecting the plastic product to composting conditions.

[0015] Another object of the present invention is to provide a method for producing monomers and / or oligomers and / or decomposition products from a plastic product containing at least one polymer, preferably PET, wherein the method comprises subjecting the plastic product to a foaming step, followed by a depolymerization step, preferably a depolymerization step which includes exposing the plastic product to a depolymerase, preferably cutinase.

[0016] A method for decomposing at least partially foamed plastic products containing at least one polymer, the method comprising contacting the at least partially foamed plastic product with a depolymerizing agent capable of decomposing at least one target polymer, optionally subjecting the polymer to an amorphization step, and contacting the at least partially foamed plastic product with a depolymerase to decompose the polymer, is a further object of the present invention.

Mode for Carrying Out the Invention

[0017] Detailed Description of the Invention Glossary of Definitions The present disclosure will be best understood by reference to the following definitions.

[0018] Within the context of the present invention, the terms "plastic article" or "plastic product" are used interchangeably and refer to any commodity or product comprising at least one polymer, such as a plastic sheet, tray, tube, rod, profile, shape, bulk block, fiber, 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 goods, etc., carpet scraps, 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 further contain additional substances or additives, such as plasticizers, inorganic substances, organic fillers, dyes, etc.

[0019] A “polymer” refers to a compound or mixture of compounds whose structure is composed of a number of repeating units (i.e., “monomers”) linked by covalent chemical bonds. In the context of the present invention, the term “polymer” refers to such compounds used in the composition of plastic products. Examples of synthetic polymers include petroleum-derived polymers, such as polyolefins, aliphatic or aromatic polyesters, polyamides, polyurethanes, and polyvinyl chlorides. In the context of the present invention, a polymer refers to a thermoplastic polymer, that is, a polymer that becomes moldable above a certain temperature and solidifies when cooled.

[0020] The term "depolymerization" in relation to a polymer or a plastic article containing a polymer means the process by which the polymer or at least one polymer in the plastic article is depolymerized and / or broken down into smaller molecules, such as monomers and / or oligomers and / or any decomposition products.

[0021] According to the present invention, "oligomer" refers to a molecule containing 2 to about 20 monomer units. As an 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, lactic acid oligomers can be recovered from PLA.

[0022] In the context of this invention, the term "polyester" refers to a polymer whose main chain contains an ester functional group. The ester functional group is characterized by carbon atoms bonded to three other atoms: a single bond to carbon, a double bond to oxygen, and a single bond to oxygen. The single-bonded oxygen atoms are bonded to another carbon atom. Depending on the composition of its 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.

[0023] In the context of this invention, "crystalline polymer" or "semicrystalline polymer" refers to a partially crystalline polymer in which crystalline and amorphous regions coexist. The crystallinity of a semicrystalline polymer can be evaluated by various analytical methods, typically ranging from 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, such as X-ray scattering (XS) (including small-angle and wide-angle XS) and infrared spectroscopy, are also suitable for less reliable evaluation of polymer crystallinity. In this disclosure, crystallinity was measured by DSC. More specifically, the DSC measurement was performed as follows: A small sample (several mg) was 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 was collected and plotted against temperature. The crystallinity Xc (%) was defined as follows:

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[0024] In the formula, ΔH f ΔH is the enthalpy of melting, which can be obtained by integrating the endothermic melting peak. cc This is the enthalpy of cold crystallization, which can be obtained by integrating the exothermic cold crystallization peak, w t ΔH is the weight fraction of polyester in the plastic. f,100%ΔH is the enthalpy of melting for perfectly crystalline polymers and can be found in the literature. For example, ΔH of PET. f,100% According to the literature, this is obtained as 125.5 J / g (Polymer Data Handbook, Second Edition, Edited by James E. Mark, OXFORD, 2009). According to the same literature, the ΔH of PLA f,100% This is equal to 93 J / g (Fisher EW, Sterzel HJ, Wegner G., Investigation of structure of solution grown crystals of lactide copolymers by means of chemical reactions, Kolloid Zeitschrift & Zeitschrift fur Polymere, 1973, 251, pp. 980-990).

[0025] The error margin for crystallinity is approximately 10%. Therefore, a crystallinity of approximately 25% corresponds to a crystallinity of 22.5% to 27.5%.

[0026] In the context of this invention, "Tg," "Tc," and "Tm" refer to the glass transition temperature, crystallization temperature, and melting temperature of a polymer, respectively. Such temperatures can be evaluated by various 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 this disclosure, the Tg, Tc, and Tm of the disclosed polymers correspond to temperatures measured by DSC.

[0027] Foaming process The inventors have shown that by subjecting a plastic product to a foaming process before subjecting the polymer to a depolymerization process, it is possible to improve the depolymerization rate of polymers contained in a plastic product, particularly polyesters and / or polyamides and / or polyolefins. The foaming process makes it possible to increase the contact surface (i.e., contact area) between the polymer and the depolymerizer. In other words, by increasing the contact surface between the plastic product and the decomposer, it is possible to improve the depolymerization rate and / or reduce the amount of decomposer and / or shorten the time required to decompose the plastic product compared to the same plastic product that has not been foamed. The present invention relates in particular to a plastic product comprising at least one thermoplastic polymer.

[0028] According to the present invention, the foaming process is carried out at a temperature in which the plastic product is partially or completely molten. In particular, the foaming process is carried out at a temperature higher than the crystallization temperature (Tc) of the target polymer of the plastic product (i.e., the polymer intended to be decomposed or depolymerized). Preferably, the plastic product is subjected to a temperature above the melting temperature (Tm) of the target polymer of the plastic product. More preferably, the plastic product is subjected to a temperature of Tm+5°C to Tm+25°C of the target polymer, preferably Tm+10°C to Tm+25°C of the target polymer, more preferably Tm+15°C to Tm+25°C, for example, Tm+20°C. In another embodiment, the plastic product is subjected to a temperature of Tm+25°C to Tm+50°C of the target polymer. In yet another embodiment, the plastic product is subjected to a temperature corresponding to or above Tm+50°C of the target polymer.

[0029] According to one embodiment of the present invention, a plastic product comprises several different polymers. In particular, the plastic product comprises at least 51% by weight of a target polymer. In such a case, the plastic product is advantageously subjected to a temperature of Tc or Tm or higher of the target polymer. Alternatively, the plastic product is subjected to a temperature of the highest Tc or Tm of the polymers contained in the plastic product.

[0030] In one specific embodiment, the plastic product includes PET, and the foaming step includes subjecting the plastic product to a temperature above 170°C, preferably 230°C or higher, more preferably 250°C to 300°C. Even more preferably, the plastic product containing PET is subjected to a temperature of 260°C to 280°C. In another embodiment, the plastic product containing PET is subjected to a temperature of 300°C or higher, preferably 300°C to 320°C.

[0031] In another specific embodiment, the plastic product includes PLA, and the foaming process includes subjecting the plastic product to a temperature of over 110°C, more preferably 145°C or higher. In a specific embodiment, the plastic product includes PLLA, and the foaming process includes subjecting the plastic product to a temperature of 170°C or higher. In yet another embodiment, the plastic product includes stereocomplex PLA, and the foaming process includes subjecting the plastic product to a temperature of 230°C or higher.

[0032] As used herein, "foaming process" refers to the process of forming cells (also called bubbles) in the structure of a plastic product by using a foaming agent (also called a leavening agent). The gas generated by the foaming agent forms bubbles in the molten or partially molten plastic material, creating closed cells and / or open cells within the plastic product. The resulting foamed plastic product exhibits a cellular structure with a density lower than that of the plastic product before the foaming process.

[0033] Depending on the method by which bubbles are formed, blowing agents can be classified as "physical blowing agents" or "chemical blowing agents." According to the present invention, the foaming process is carried out by using one or more blowing agents selected from physical blowing agents, chemical blowing agents, and mixtures thereof. In one specific embodiment, the foaming process is carried out by using a physical blowing agent. Alternatively, the foaming process is carried out by using a chemical blowing agent. In another embodiment, the foaming process is carried out by using both a physical blowing agent and a chemical blowing agent.

[0034] In the context of the present invention, “physical blowing agent” means a compound that undergoes a physical change of state during processing. Physical blowing agents include pressurized gases that expand when returned to atmospheric pressure during the blowing process (e.g., nitrogen, carbon dioxide, methane, helium, neon, argon, xenon, and hydrogen, or mixtures thereof) and low-boiling point liquids that expand by changing from a liquid to a gaseous state when heated, thereby producing a larger volume of vapor (e.g., pentane, isopentane, hexane, methylene chloride, and dichlorotetrafluoroethane).

[0035] In one specific embodiment, the physical blowing agent is a gas. Preferably, the physical blowing agent is selected from the group consisting of nitrogen, carbon dioxide, argon, helium, methane, neon, xenon, hydrogen, or mixtures thereof. More preferably, the physical blowing agent is selected from carbon dioxide and nitrogen. In another embodiment, the physical blowing agent is selected from the group consisting of saturated aliphatic hydrocarbons, e.g., methane, ethane, propane, butane, pentane, and hexane; saturated alicyclic hydrocarbons, e.g., cyclopentane, cyclohexane, ethylcyclopentane; aromatic hydrocarbons, e.g., benzene, toluene, xylene; halogenated saturated hydrocarbons, e.g., methylene chloride, carbon tetrachloride; ethers, e.g., methylal, acetal, 1,4-dioxane; and ketones, e.g., acetone, methyl ethyl ketone, and acetyl ketone, or mixtures thereof. Alternatively, the physical blowing agent is selected from low-boiling point liquids selected from the group consisting of pentane, isopentane, hexane, methylene dichloride, and dichlorotetrafluoroethane. In particular, low-boiling-point liquids have a boiling point lower than the temperature at which the plastic product is partially or completely molten. In one embodiment, the foaming process can be carried out using one or more of the physical foaming agents listed above. In one specific embodiment, the polymer of the plastic article subjected to the foaming process using the physical foaming agent has an intrinsic viscosity index greater than 0.5, preferably greater than 0.6.

[0036] In one specific embodiment, a physical blowing agent is injected into a partially or entirely molten plastic product. In other words, the plastic product is first heated, and once it melts, the physical blowing agent is injected into the molten material.

[0037] In the context of the present invention, "chemical blowing agent" refers to a blowing agent that undergoes a decomposition reaction during polymer heating at a given temperature, resulting in the release of gases such as nitrogen, carbon dioxide, carbon monoxide, nitric oxide, NOx compounds, ammonia, and / or water vapor. Such chemical blowing agents can be selected from the group consisting of azides, hydrazides, e.g., p,p'-hydroxybis-(benzenesulfonyl hydrazide), semicarbazides, e.g., p-toluenesulfonyl semicarbazide, p-toluenesulfonyl semicarbazide, azo compounds, e.g., azodicarboxamide, triazoles, e.g., nitrotriazolone, tetrazoles, e.g., 5-phenyltetrazole, bicarbonates, e.g., zinc bicarbonate or alkali bicarbonates, e.g., sodium bicarbonate, anhydrous substances, peroxides, nitro compounds, and perchlorates. Alternatively, the chemical blowing agent may be selected from citric acid, carbonates, bicarbonates, and mixtures thereof, or any commercially available chemical blowing agent, such as HYDROCEROL® from Clariant or Orgater® from Adeka. Preferably, the chemical blowing agent includes a mixture of citric acid and carbonate and / or a mixture of citric acid and bicarbonate. Alternatively, the chemical blowing agent may include hydrogen peroxide. In one embodiment, the blowing process may be carried out using one or more of the chemical blowing agents listed above.

[0038] In one specific embodiment, the foaming process includes mixing one or more chemical foaming agents with a plastic product at ambient temperature, and then subjecting the mixture to a temperature at which the plastic product is partially or completely molten.

[0039] In another embodiment, a chemical blowing agent is added to a plastic product that has been at least partially molten. In other words, the plastic product is first heated, and once it has melted, the chemical blowing agent is mixed into the molten material.

[0040] In one embodiment, the foaming process is carried out using both a chemical blowing agent (one or more) and a physical blowing agent (one or more).

[0041] In one embodiment, the method of the present invention includes contacting 0.1 to 10% by weight, preferably 0.1 to 5% by weight, of a single or multiple foaming agent based on the total weight of the mixed foaming agent / plastic product, with 90 to 99.9% by weight, preferably 95 to 99.9% by weight, of the plastic product. In particular, the method of the present invention includes contacting 0.1 to 10% by weight of a chemical foaming agent based on the total weight of the mixed foaming agent / plastic product, with 90 to 99.9% by weight, of the plastic product. Preferably, the method of the present invention includes contacting 1 to 5% by weight of a chemical foaming agent with 95 to 99% by weight, of the plastic product. Alternatively, the method of the present invention includes contacting 0.1 to 5% by weight, preferably 0.1 to 3% by weight, more preferably 0.1 to 1% by weight, of a chemical foaming agent with 95 to 99.9% by weight, preferably 97 to 99.9% by weight, more preferably 99 to 99.9% by weight, of the plastic product. In another embodiment, the method of the present invention includes contacting 0.1 to 5% by weight of a physical blowing agent with 95 to 99.9% by weight of a plastic product, based on the total weight of the mixed blowing agent / plastic product. Preferably, the method of the present invention includes contacting 0.1 to 3.5% by weight of a physical blowing agent with 96.5 to 99.9% by weight of a plastic product.

[0042] In one embodiment, the foaming process is carried out using one or more foaming agents and processing aids, such as wax, nucleating agents, chain extenders, foam kickers, or water, preferably water. In particular, the foaming process is carried out using one or more foaming agents and 0.01 to 10% by weight, preferably 0.01 to 1% by weight, of the processing aids, based on the total weight of the mixed foaming agents / plastic product / processing aids. Preferably, the foaming process is carried out using a chemical foaming agent and water, more preferably a mixture of citric acid and water.

[0043] In one embodiment, the foaming process is carried out using an extruder, and the plastic product is subjected to a temperature at which it is partially or entirely molten. The foaming agent can be introduced into the extruder before heating, during heating, and / or when the material is heated and already molten.

[0044] In another embodiment, the foaming process is carried out by batch foaming using an autoclave, saturating the plastic product with a foaming agent, then subjecting it to rapid depressurization, and optionally placing it in a hot oil bath. For example, pressure-induced or temperature-induced foaming can be used. Batch foaming is particularly suitable for plastic products (e.g., composites containing glass fibers or carbon fibers) that include at least one polymer and additional components that may be subjected to decomposition in an extruder.

[0045] Alternatively, the foaming and / or cooling processes can be carried out by any technique known to those skilled in the art.

[0046] Advantageously, the plastic product before the foaming process exhibits a porosity of less than 10%, preferably less than 5%, and more preferably less than 3%. In one embodiment, the plastic product that has been at least partially foamed exhibits a porosity of 20% to 90%, preferably 25% to 50%. In particular, the porosity is 30% to 40%. Alternatively, the plastic product exhibits a porosity of more than 20%, preferably more than 30%, and more preferably more than 40%. As used herein, the term "porosity" means the void ratio in a plastic product, and corresponds to the ratio of the volume of voids (i.e., pores) in the plastic product to the total volume of the plastic product.

[0047] Porosity can be evaluated by any method known to those skilled in the art. Preferably, the "porosity" (ε) of a plastic product is evaluated. T ) is evaluated using the following equation.

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[0048] The water pycnometer method consists of measuring the mass of a specific volume of water and the mass of the same volume containing the foamed plastic product for which the density is to be determined. If the density (i.e., true density) of the original (i.e., non-foamed) plastic product is known, the apparent density of the sample can thereby be determined and the porosity of the material can be calculated. As an example, the literature value for the true density of a plastic product containing 100% PET is 1380 kg.m -3 which corresponds to the density of PET. The water pycnometer method is particularly suitable for calculating the density of products with irregular shapes. In the case of products with regular shapes (e.g., cylinders), the volume of the product can be calculated directly and, for this reason, its apparent density can be evaluated. If the plastic product is a fabric, the true density

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[0049] In a specific embodiment, the at least partially foamed plastic product contains at least 95% PET and has an apparent density of less than 1000 kg.m -3 preferably less than 900 kg.m -3 less than the apparent density

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[0050] In one embodiment, the at least partially foamed plastic product is a at least partially foamed fabric containing at least 85% PET and exhibiting a porosity of 10% to 70%.

[0051] In one embodiment, the plastic product is subjected to a pretreatment step before the foaming step. The pretreatment step may include sorting and / or washing and / or disinfecting and / or sterilizing and / or biologically cleaning the plastic product before foaming. Alternatively or additionally, the pretreatment step may include physically converting the plastic product into film, flakes, powder, pellets or fibers before foaming.

[0052] The method of the present invention is particularly suitable for plastic products containing PET. Therefore, one object of the present invention is to provide a method for decomposing a plastic product containing at least PET, comprising the steps of at least partially foaming the plastic product and depolymerizing the PET in the at least partially foamed plastic product, wherein the foaming step is preferably carried out using a chemical blowing agent, more preferably citric acid, carbonate, bicarbonate and mixtures thereof, more preferably a mixture of citric acid and carbonate or a mixture of citric acid and bicarbonate.

[0053] As mentioned above, the present invention is particularly suitable for plastic products containing thermoplastic polymers. Furthermore, the present invention can also be implemented using plastic products containing thermosetting polymers by adapting the foaming process.

[0054] cooling process In one specific embodiment, the method of the present invention further includes a step of cooling the at least partially foamed plastic product after the foaming step. In fact, as described above, the foaming step is carried out using a plastic product heated to a molten state. According to one embodiment, after the foaming step, the foamed plastic product is subjected to a temperature lower than the temperature of the foamed plastic product in order to rapidly lower the temperature of the foamed plastic product and to promote the solidification of the foamed plastic product. The cooling step includes bringing the plastic product into contact with any cooling fluid, including air and / or liquid.

[0055] In one specific embodiment, the plastic product is subjected to a cooling process for less than 30 seconds, more preferably less than 20 seconds, and even more preferably less than 10 seconds, after the foaming process. In particular, the plastic product is subjected to the cooling process immediately after the completion of the foaming (i.e., heating) process.

[0056] Such rapid cooling after the heating stage makes it possible to at least partially amorphous one or more polymers in the plastic product. Amorphization occurs by at least partially destroying the crystalline structure of the polymer in the plastic product during the foaming process (i.e., the heating process) and fixing the heated polymer in an amorphous state by rapid cooling. Therefore, polymer amorphization can be performed during the foaming process by subjecting the plastic product to a temperature above the polymer's Tc, preferably above its Tm, and then rapidly cooling the plastic product to a temperature below the polymer's Tc and / or Tg.

[0057] As used herein, the terms “amorphization” and “to amorphize” mean, with respect to polymers, a decrease in the crystallinity of a given polymer compared to its crystallinity before amorphization. Preferably, amorphization makes it possible to reduce the crystallinity of a target polymer by at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 60%, 70%, 80%, or 90% compared to its crystallinity before amorphization. Advantageously, amorphization results in a polymer having a crystallinity of up to 30%, preferably up to 25%, more preferably up to 20%, and even more preferably up to 15%. Alternatively, amorphization makes it possible to maintain the crystallinity of a polymer at less than 30%, preferably less than 25%, more preferably less than 20%, and even more preferably less than 15%. Amorphization can be carried out by any method known to those skilled in the art to at least partially disrupt the crystalline structure of the polymer, in particular by any method described in WO2017 / 198786. Thereafter, amorphization improves the depolymerization ability of the polymer by biological agents.

[0058] The foaming and cooling temperatures can be adapted by those skilled in the art according to the target polymer. Similarly, those skilled in the art know when and how to degass during the foaming process, before and / or after the introduction of the foaming agent. Generally speaking, the plastic product can be subjected to heat treatment for a period sufficient to obtain amorphous formation of the target polymer, and optionally subjected to shear stress. For example, depending on the temperature and / or the plastic product, such a period can include 10 seconds to several minutes. In a preferred embodiment, the foaming process involves subjecting the plastic product to both shear stress and a temperature greater than the Tc of the target polymer of the plastic product, preferably greater than or equal to the Tm of the polymer. Preferably, heating and shear stress are performed simultaneously to improve amorphous formation during the foaming process.

[0059] According to the present invention, the cooling step includes subjecting the foamed plastic product to a temperature below the Tc of the target polymer of the plastic product, preferably below the Tg of the polymer. Subjecting the plastic product to a temperature below the Tc of the target polymer is specifically adapted to, for example, PBAT, or any polymer with a Tg of less than 20°C. In another embodiment, cooling is performed by subjecting the heated plastic product to a temperature at least 20°C lower than the Tc of the target polymer, preferably at least 30°C, 40°C, or 50°C lower. In one embodiment, cooling is performed by subjecting the plastic product to room temperature (i.e., 25°C ± 5°C). In yet another embodiment, cooling is performed by subjecting the plastic product to a temperature of about 20°C or about 10°C.

[0060] Generally speaking, plastic products are subjected to a cooling temperature for a period sufficient to lower the temperature of the core of the plastic product. For example, depending on the initial temperature of the foamed plastic product (i.e., before the cooling process) and / or the cooling temperature and / or properties / form of the plastic product, such a period can range from one second to several minutes. In one embodiment, the plastic product is in the form of an extruded article having a diameter of less than 1 cm, preferably 0.5 to 5 mm, and is subjected to a cooling temperature for less than one minute, preferably less than 30 seconds, more preferably less than 20 seconds, and even more preferably less than 10 seconds. Alternatively, the foamed plastic material coming out of the extruder is formed into a tube or sheet.

[0061] As an example, cooling can be performed following the foaming process by immersing the plastic product in a liquid at a cooling temperature. For example, at least partially foamed plastic products are immersed in a liquid at room temperature, more preferably below room temperature, at the end of the foaming process. For example, the plastic article is immersed in a cold liquid with a temperature of less than 14°C, preferably less than 10°C or less than 5°C. In one specific embodiment, the plastic product is immersed in cold water, for example, water below 5°C. Alternatively, the plastic article is immersed in a liquid whose temperature is below the Tc of the target polymer. More generally, any method suitable for rapidly lowering the temperature of the plastic product (e.g., cold air) can be used.

[0062] In one preferred embodiment, the foaming process is carried out in an extruder. The extruder allows the plastic product to be subjected to both a given temperature and shear stress simultaneously or continuously. Advantageously, the foamed plastic product emerging from the extruder is cooled directly by immersion and / or spraying of water. Advantageously, the extruder can be selected from a single-screw extruder, a multi-screw extruder with either co-rotating or counter-rotating design, a planetary roller extruder, a dispersion kneader, a reciprocating single-screw extruder (co-kneader), a mini-extruder, or an internal mixer.

[0063] In one embodiment, an underwater pelletizer or underwater strand pelletizer, which enables the direct cutting of plastic material in cold water, is fixed to the head of an extruder to produce plastic pellets that are immediately subjected to the cooling stage. In such embodiments, the plastic product is in the form of pellets less than 1 cm in size, preferably 0.5 to 5 mm, and is subjected to a cooling temperature for less than 1 minute, preferably less than 30 seconds, more preferably less than 20 seconds, and even more preferably less than 10 seconds. In particular, a microgranulating underwater pelletizer that produces mini-pellets of less than 1 mm is fixed to the head of the extruder.

[0064] Alternatively, the foaming process may be carried out in an autoclave, and the foamed plastic product may be cooled by contact with ambient air or cooling air, or by immersion in a liquid at or below room temperature. Alternatively, the foaming and cooling processes may be carried out by any technique known to those skilled in the art.

[0065] Therefore, a method for decomposing a plastic product containing at least one polymer, a. A step of foaming a plastic product at least partially, wherein the foaming step is carried out at a temperature above the crystallization temperature (Tc) of the target polymer of the plastic product, preferably above the melting temperature (Tm) of the polymer. b. A step of cooling the at least partially foamed plastic product to a temperature below the Tc of the polymer, preferably below the glass transition temperature (Tg) of the polymer, c. To provide a method comprising the step of depolymerizing the target polymer is one object of the present invention.

[0066] Advantageously, the blowing agent is selected from chemical blowing agents. Preferably, the plastic product is subjected to a cooling step less than 30 seconds after the foaming step, more preferably immediately afterward.

[0067] Advantageously, the partially foamed plastic product is subjected to a granulation step between a cooling step (b) and a depolymerization step (c) to obtain the pellets described above.

[0068] In one specific embodiment, the target polymer, which is at least partially amorphous and foamed, exhibits a crystallinity of up to 30%, preferably up to 25%, and more preferably up to 20%. Preferably, the depolymerization step is carried out using a biological depolymerizer.

[0069] In another embodiment, the extruder further comprises a spinneret for melt spinning nonwoven products or for melt spinning monofilaments or multifilaments, and the cooling process is preferably carried out using cooling air.

[0070] Therefore, a method for decomposing a plastic product containing at least one polymer, a. A step of foaming and melt-spinning the plastic product, wherein the foaming and melt-spinning step is performed at a temperature above the Tc of the polymer, preferably above the Tm of the target polymer. b. A step of cooling the at least partially foamed and spun plastic product to a temperature below the Tc of the target polymer, preferably below the Tg of the polymer, c. A step of depolymerizing the target polymer, Another object of the present invention is to provide a method for carrying out the foaming and melt-spinning steps using an extruder equipped with a spinneret.

[0071] Advantageously, the blowing agent is selected from chemical blowing agents, and / or the plastic product is subjected to a cooling process less than 30 seconds after the spinning process, preferably immediately after the spinning process, and / or depolymerization is carried out using enzymes.

[0072] One specific object of the present invention is to provide a method for decomposing the plastic products described above, wherein the plastic product includes PET. Advantageously, the foaming step is carried out in an extruder, and the cooling step is performed by subjecting the heated, partially foamed plastic product to a temperature of less than 30 seconds after the foaming step, preferably less than 90°C, preferably immediately after the foaming step. Alternatively, the cooling step is performed by subjecting the heated plastic product to a temperature of less than 50°C. In particular, the polymer is PET, and at least partially amorphous PET exhibits a crystallinity of up to 30%, preferably up to 25%, more preferably up to 20%.

[0073] In particular, a method for decomposing plastic products containing at least PET, a. A step of foaming a plastic product with a foaming agent, wherein the foaming step is carried out at a temperature of over 170°C, preferably over 185°C, more preferably over 200°C, and even more preferably over 220°C, 230°C, 240°C, 245°C, 250°C, 255°C, 260°C, and 265°C. b. A step of cooling the at least partially foamed plastic product at a temperature of less than 100°C, preferably less than 90°C, preferably less than 30 seconds after the foaming step, c. To provide a method comprising the step of depolymerizing the PET is one object of the present invention.

[0074] Advantageously, the blowing agent is selected from chemical blowing agents, preferably from citric acid, carbonate, bicarbonate, or a mixture thereof, and / or the plastic product is subjected to a cooling step less than 30 seconds after the foaming step. Advantageously, the PET in the foamed product exhibits a degree of crystallinity of less than 20%, more preferably less than 5%, after the cooling step, and the depolymerizing agent is an esterase, preferably cutinase or lipase, more preferably cutinase.

[0075] Depolymerization process According to the present invention, the decomposition method includes a foaming step and an optional cooling step, followed by a depolymerization step of at least one polymer of the plastic product. In a preferred embodiment, the depolymerization step targets at least one polymer that has already been amorphous.

[0076] In one specific embodiment, the depolymerization step includes contacting the plastic product with a depolymerizing agent, i.e., a chemical and / or biological agent.

[0077] Advantageously, the depolymerization process is carried out in a liquid medium containing a depolymerizing agent.

[0078] In another specific embodiment, the plastic product is brought into contact with a depolymerizer before the depolymerization step. For example, the plastic product is immersed in a liquid containing the depolymerizer after the foaming step. In particular, the plastic product can be brought into contact with the depolymerizer during the cooling step (i.e., immersed in a coolant containing the depolymerizer). In one embodiment, the depolymerization step is carried out by immersing the plastic product in a liquid. In a preferred embodiment, such a liquid has had the depolymerizer removed. In another embodiment, the depolymerization step is carried out by subjecting the plastic product to composting conditions. In particular, the plastic product is subjected to industrial composting conditions at temperatures above 50°C and / or household composting conditions at temperatures between 15°C and 35°C. In one embodiment, the foamed plastic product is brought into contact with the depolymerizer during the cooling step, and the depolymerization step is carried out thereafter by subjecting the plastic product to a stimulus that can activate the depolymerizer. For example, the depolymerizer is a degrading enzyme, and the stimulus consists of a specific temperature and / or humidity.

[0079] In one specific embodiment, the depolymerizer is a biological agent or comprises a biological agent. In particular, the biological agent is a depolymerase (i.e., an enzyme). Preferably, the depolymerase is capable of degrading at least one polymer of a plastic product, preferably at least one polymer that has already been amorphous.

[0080] Depolymerases are 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), oligomeric hydrolases, such as 6-aminohexanoate cyclic dimer hydrolase (EC 3.5.2.12), 6-aminohexanoate dimer hydrolase (EC 3.5.1.46), 6-aminohexanoate oligomeric hydrolase (EC 3.5.1.B17), oxidases, peroxidases, laccases (EC 1.10.3.2), oxygenases, lipoxygenases, monooxygenases, or lignin-degrading enzymes. In one specific embodiment, a plastic product is brought into contact with at least two types of depolymerases.

[0081] In one specific embodiment, the plastic product comprises PET, and the depolymerase is an esterase. In particular, the depolymerase is a cutinase, preferably one 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, e.g., LC-cutinases described in Sulaiman et al., 2012, or esterases described in EP3517608, or any functional variants thereof, including depolymerases listed in WO2018 / 011284 or WO2018 / 011281. In another specific embodiment, the depolymerase is preferably a lipase produced by Ideonella sakaiensis. In yet another specific embodiment, the depolymerase is a cutinase produced by Humicola insolens, for example, the one referred to as A0A075B5G4 in Uniprot, or any functional variant thereof. In yet another embodiment, the depolymerase is selected from commercially available enzymes, for example, Novozym 51032, or any functional variant thereof.

[0082] In one specific embodiment, the plastic product comprises PLLA, and the depolymerase is preferably a protease produced by a microorganism selected from Amycolatopsis sp, Amycolatopsis orientalis, Tritirachium album (proteinase K), Actinomadura keratinilytica, Laceyella sacchari LP175, Thermus sp, or any commercially available enzyme known to degrade PLA, such as Savinase®, Esperase®, Everlase®, or any functional variant thereof, including the depolymerases listed in WO2016 / 062695, WO2018 / 109183, or WO2019 / 122308.

[0083] In another specific embodiment, the plastic product comprises PDLA, and the depolymerase is an esterase, preferably a cutinase or lipase, more preferably selected from CLE from Cryptococcus sp., Burkholderia cepacia, Paenibacillus amylolyticus TB-13, Candida Antarctica, Rhiromucor miehei, Saccharomonospora viridis, lipase PS from Cryptococcus magnus, or any functional variant thereof.

[0084] In another specific embodiment, the plastic product comprises PA, and the depolymerase is selected from the group consisting of amidases, aryl acylamidases (EC 3.5.1.13), oligomeric hydrolases, such as 6-aminohexanoate cyclic dimer hydrolase (EC 3.5.2.12), 6-aminohexanoate dimer hydrolase (EC 3.5.1.46), and 6-aminohexanoate oligomeric hydrolase (EC 3.5.1.B17).

[0085] In another specific embodiment, the plastic product comprises a polyolefin, and the depolymerase is preferably an oxidase selected from the group consisting of laccase, peroxidase, oxygenase, lipoxygenase, monooxygenase, or lignin-degrading enzyme.

[0086] In another embodiment, the depolymerizer is a microorganism that expresses and secretes depolymerase. The microorganism may synthesize depolymerase naturally, or it may be a recombinant microorganism in which a recombinant nucleotide sequence encoding depolymerase has been inserted, for example, using a vector. A specific embodiment of the depolymerization step can be found in WO2017 / 198786.

[0087] According to the present invention, different types of polymers contained in the same plastic article can be depolymerized by using several microorganisms and / or purified enzymes and / or synthetic enzymes in combination or sequentially, and polymers contained in different plastic articles that are simultaneously subjected to the decomposition step of the present invention can also be depolymerized.

[0088] The time required to depolymerize at least one polymer of a plastic article can vary depending on the plastic article and the target polymer (i.e., the properties and origin of the plastic article, its composition, shape, molecular weight, etc.), the type and amount of microorganisms / enzymes used, and various process parameters (i.e., temperature, pH, additional agents, etc.). Those skilled in the art can easily adapt the process parameters to the plastic article and / or the depolymerase.

[0089] In one specific embodiment, the plastic product comprises PET, and the depolymerization process is carried out by contacting the plastic product with a biological depolymerizing agent at a temperature encompassing 20°C to 90°C, preferably 30°C to 80°C, more preferably 40°C to 75°C, more preferably 50°C to 75°C, and even more preferably 60°C to 75°C. Furthermore, the depolymerization process is carried out at a pH of preferably 5 to 11, preferably 7 to 9, more preferably 7 to 8.5, and even more preferably 7 to 8. Alternatively, the depolymerization process can be carried out under industrial and / or composting conditions.

[0090] In one specific embodiment, the plastic product comprises PLA, and the depolymerization process is carried out by contacting the plastic product with a biological depolymerizer at a temperature encompassing 20°C to 90°C, preferably 20°C to 60°C, more preferably 30°C to 55°C, more preferably 40°C to 50°C, and even more preferably 45°C. Furthermore, the depolymerization process is carried out at a pH of preferably 5 to 11, preferably 7 to 10, more preferably 8.5 to 9.5, and even more preferably 8 to 9. In another specific embodiment, the depolymerization process can be carried out at a pH of 7 to 8. Alternatively, the depolymerization process can be carried out under industrial and / or composting conditions.

[0091] In another specific embodiment, the depolymerizer is a chemical agent or comprises a chemical agent. In particular, the chemical agent is a catalyst selected from metal catalysts, or a stable and non-toxic hydrosilane (PMHS, TMDS), for example, commercially available B(C6F5)3 and [Ph3C + ,B(C6F5)4 -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, and zeolites. 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.In particular, catalysts include germanium dioxide, cobalt acetate, titanium tetrachloride, titanium phosphate, titanium tetrabutoxide, titanium tetraisopropoxide, titanium tetra-n-propoxide, titanium tetraethoxide, titanium tetramethoxide, tetrakis(acetylacetonate)titanium complex, tetrakis(2,4-hexanedionato)titanium complex, tetrakis(3,5-heptanedionato)titanium complex, dimethoxybis(acetylacetonate)titanium complex, diethoxybis(acetylacetonate)titanium complex, diisopropoxybis(acetylacetonate)titanium complex, di-n-propoxybis(acetylacetonate)titanium complex, dibutoxybis(acetylacetonate)titanium complex, titanium dihydroxybisglycolate, titanium dihydroxybisglycolate, titanium dihydroxybislactate, titanium dihydroxybis(2-hydroxypropionate), and titanium lactate. The catalyst comprises at least one of the following: titanium octane diolate, titanium dimethoxybistriethanol aminate, titanium diethoxybistriethanol aminate, titanium dibutoxybistriethanol aminate, hexamethyl dititanalate, hexaethyl dititanalate, hexapropyl dititanalate, hexabutyl dititanalate, hexaphenyl dititanalate, octamethyl trititanalate, octaethyl trititanalate, octapropyl trititanalate, octabutyl trititanalate, octaphenyl trititanalate, hexaalkoxy dititanalate, 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 may be selected from nanoparticles. The chemical agent can be selected from any catalyst known to those skilled in the art to have the ability to decompose and / or depolymerize the target polymer.

[0092] Alternatively, the chemical agent is an acid or base catalyst capable of breaking polymer bonds, particularly ester bonds. In particular, the chemical agent involved in breaking ester bonds is a mixture of a hydroxide and an alcohol capable of dissolving the hydroxide. The hydroxide is selected from alkali metal hydroxides, alkaline earth metal hydroxides, and ammonium hydroxide, preferably from sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, magnesium hydroxide, ammonium hydroxide, and tetraalkylammonium hydroxide. The alcohol is selected from linear, branched, cyclic alcohols, or combinations thereof, preferably linear C1-C4 alcohols selected from methanol, ethanol, propanol, and butanol.

[0093] In one specific embodiment, the chemical agent is a mixture of a polymer that can be swelled by a nonpolar solvent (i.e., a swelling agent) and an agent that can break or hydrolyze ester bonds, the swelling agent being preferably a chlorinated solvent selected from dichloromethane, dichloroethane, tetrachloroethane, chloroform, tetrachloromethane, and trichloroethane. In another specific embodiment, the chemical agent is an acid selected from ethylene glycol, hydrochloric acid, sulfuric acid, or Lewis acid.

[0094] In one specific embodiment, a plastic product that is at least partially foamed and optionally amorphous can be subjected to cryogenic grinding, freezer milling, or cryogenic milling before the depolymerization step. In one embodiment, the plastic product is crushed or ground before the depolymerization step. Advantageously, the plastic product is not subjected to a pulverization step before the depolymerization step.

[0095] Plastic items The inventors have developed a decomposition method for decomposing plastic products containing polymers, preferably thermoplastic polymers, such as polyester and / or polyamide and / or polyolefin. The method of the present invention can be advantageously used for plastic articles from plastic waste collection and / or industrial waste. In particular, the method of the present invention can be used to decompose household plastic waste, including plastic bottles, plastic trays, plastic bags and plastic packaging, and soft and / or rigid plastics, which may be contaminated with food residues, surfactants, etc. Alternatively or additionally, the method of the present invention can be used to decompose used plastic fibers, such as cloth, textiles and / or fibers from industrial waste. More specifically, the method of the present invention can be used for PET plastic and / or PET fiber waste, such as cloth, textiles or PET fibers from tires. Interestingly, the method of the present invention makes it possible to produce monomers and / or oligomers and / or any further recoverable and / or reprocessable decomposition products.

[0096] In one specific embodiment, the plastic product is selected from unfoamed plastic waste including plastic bottles, plastic bags and plastic packaging, soft and / or rigid plastics, fibers, textiles, and / or thermoplastic polymers, and from foamed plastic products having a crystallinity of more than 30%. Such foamed plastic products are subjected to a new foaming process during heating and a cooling process for amorphous formation before depolymerization.

[0097] In one specific embodiment, the method of the present invention is used to decompose a plastic product containing at least one thermoplastic polymer, in particular one semicrystalline thermoplastic polymer.

[0098] Advantageously, the method of the present invention can be applied to polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene isosorbide terephthalate (PEIT), polylactic acid (PLA), polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polyethylene furanoate (PEF), and polycaprolactone (PCL). The method of the present invention is used to decompose plastic products containing at least one polyester selected from poly(ethylene adipate) (PEA), polyethylene naphthalate (PEN), polycyclohexylene dimethylene terephthalate (PCT), polyethylene succinate (PES), poly(butylene succinate-co-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 decompose plastic products containing at least one aromatic polyester selected from 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.

[0099] In one specific embodiment, the method of the present invention is used to decompose a plastic product containing at least one polyester, preferably at least PET or PLA.

[0100] Alternatively, the method of the present invention can be performed using polyamide-6 or poly(β-caprolactam) or polycaproamide (PA6), polyamide-6,6 or poly(hexamethyleneadipamide) (PA6,6), poly(11-aminoundecanoamide) (PA11), polydodecanolactam (PA12), poly(tetramethyleneadipamide) (PA4,6), poly(pentamethylenesebacamide) (PA5,10), poly(hexamethyleneazelaamide) (PA6,9), poly(hexamethylenesebac It is used to decompose plastic products containing at least one polyamide selected from PA66 / 6I, poly(hexamethylene dodecanoamide) (PA6,10), poly(hexamethylene dodecanoamide) (PA6,12), poly(m-xylylene adipamide) (PAMXD6), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (PA66 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (PA66 / 6I), and blends / mixtures of these materials.

[0101] Alternatively, the method of the present invention can be used to decompose plastic products comprising polyethylene, polypropylene, polymethylpentene, polybutene-1, polyisobutylene, ethylene propylene rubber, ethylene propylene diene monomer rubber, ethylene vinyl alcohol, one or more ethylene-carbon monoxide copolymers, and at least one polyolefin selected from these copolymers and modified products.

[0102] In one specific embodiment, the plastic product comprises at least two polymers. More generally, the plastic product targeted by the method of the present invention may include heterogeneous polymers, such as synthetic polymers derived from petrochemicals, e.g., polyamides, polyolefins, or vinyl polymers, or bio-based sources, e.g., rubber, wood, or wood compounds, e.g., lignin, cellulose, or hemicellulose and starch, and their derivatives. Alternatively, the plastic product may include at least one polymer and additional components, e.g., metal compounds, inorganic compounds, glass compounds, natural or synthetic fibers (e.g., glass fibers or carbon fibers), paper, and derivatives thereof as defined in WO 2015 / 173265.

[0103] Interestingly, the method of the present invention makes it possible to produce monomers and / or oligomers and / or further recoverable and / or reprocessable degradation products.

[0104] Manufacturing of monomers / oligomers / decomposition products Another object of the present invention is to provide a method for producing monomers and / or oligomers and / or decomposition products from a plastic product containing at least one polymer, the method comprising: a foaming step of foaming the plastic product at least partially; a cooling step of optionally amorphousizing the polymer in the plastic product at least partially; and a depolymerization step of at least the polymer in the plastic product.

[0105] Another object of the present invention is to provide a method for decomposing a plastic product containing at least one polymer, wherein the plastic product is already foamed, the polymer of the plastic product is optionally at least partially amorphous, and the plastic product is brought into contact with a depolymerizing agent capable of decomposing the polymer, preferably a biological agent, more preferably a depolymerase. In one specific embodiment, the plastic product is depolymerized under composting conditions or environmental conditions. In particular, the plastic product is subjected to industrial composting conditions at temperatures above 50°C and / or household composting conditions at temperatures between 15°C and 35°C. In such cases, the polymer of the plastic product can be decomposed into water and / or carbon dioxide and / or methane by microorganisms in the compost and / or environment.

[0106] Another object of the present invention is to provide a method for decomposing plastic products, further comprising a step of purifying monomers and / or oligomers and / or decomposition products obtained from the depolymerization step. The monomers and / or oligomers and / or decomposition products obtained from depolymerization can be recovered sequentially or continuously. Depending on the polymer and / or starting plastic article, 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 decomposition products can be purified using any suitable purification method and prepared into a repolymerizable form. In one preferred embodiment, the repolymerizable monomers and / or oligomers can then be reused to synthesize polymers. Those skilled in the art can easily adapt process parameters to the monomers / oligomers and the polymer to be synthesized.

[0107] A further object of the present invention is to provide a method for recycling a plastic product containing at least one polymer, comprising subjecting the at least one plastic product to a foaming step and a depolymerization step in sequence, and recovering monomers and / or oligomers of such polymer.

[0108] Another object of the present invention is to provide a method for decomposing a partially foamed plastic product containing at least one polymer, wherein the partially foamed plastic product is produced from plastic waste and / or textile waste, and the at least one polymer is contacted with a decomposable depolymerizing agent, preferably a biological agent, more preferably a depolymerase. In particular, the partially foamed plastic product is obtained from plastic waste and / or textile waste that has already been subjected to a foaming process. In particular, the plastic waste and / or textile waste has been subjected to a foaming process using a chemical foaming agent, a physical foaming agent, or both a chemical and a physical foaming agent. In one specific embodiment, the polymer in the partially foamed plastic product is amorphous, and the partially foamed plastic product is contacted with a depolymerizable biological agent, preferably a depolymerase, in order to decompose the amorphous polymer. The foaming and amorphous processes can be carried out according to the specific embodiment described above.

[0109] In particular, one object of the present invention is to provide a method for recycling plastic products selected from plastic waste and / or textile waste, comprising at least one polymer, wherein the plastic waste and / or textile waste is already foamed, and the method includes the step of depolymerizing the at least one polymer by contacting the product with a depolymerizing agent, preferably a biological agent, more preferably a depolymerase. In one embodiment, the plastic product selected from plastic waste and / or textile waste is pre-foamed according to one specific embodiment described above. In particular, the plastic product is pre-foamed by using a chemical blowing agent or a physical blowing agent, or both a chemical blowing agent and a physical blowing agent. In one specific embodiment, the polymer of the plastic product is pre-foamed before contact with a depolymerizing agent, preferably a biological agent, more preferably a depolymerase that can degrade the amorphous polymer. In one embodiment, the plastic product selected from plastic waste and / or textile waste is pre-foamed according to one specific embodiment described above.

[0110] Therefore, one object of the present invention is to use a foamed plastic product containing at least one polymer and subject such a foamed plastic product to a depolymerization step to produce monomers and / or oligomers of such polymers. Preferably, the foamed plastic product includes plastic waste and / or fiber waste that has already been foamed and whose polymer has been optionally already amorphous.

[0111] All of the specific embodiments described above in relation to methods for breaking down plastic products also apply to methods for producing monomers and / or oligomers, as well as methods for recycling them.

[0112] Manufacturing of biodegradable plastics Another object of the present invention is to provide a plastic product that contains at least one target polymer and incorporates at least one enzyme capable of degrading the target polymer, wherein the enzyme is incorporated into the plastic product according to the process described below. a. The plastic product is preferably at least partially foamed with a foaming agent selected from chemical foaming agents, wherein the foaming step is performed at a temperature above the Tc, preferably above the Tm, of the target polymer. b. Cool the at least partially foamed plastic product within 30 seconds after the foaming step by immersing the plastic product in a liquid containing a depolymerizer (i.e., an enzyme capable of decomposing the target polymer) at a temperature below the Tc and / or Tg of the target polymer.

[0113] Further aspects and advantages of the present invention will be disclosed in the following examples. These examples should be considered illustrative and not limiting the scope of this application. These examples provide experimental data and means for carrying out the present invention that support it. [Examples]

[0114] example Example 1 - A method for decomposing plastic products, including PET, including a foaming process using a chemical foaming agent. A) A foaming process using a chemical foaming agent (CFA), and a subsequent cooling process. a. Clariant HYDROCEROL PEX 5048 as CFA Washed and colored flakes from bottle waste containing 98% PET and having an average crystallinity of 34.5% were foamed using a Leistritz ZSE 18 MAXX twin-screw extruder, which includes nine continuous heating zones (Z1-Z9) and a head (Z10) that allow for independent temperature control and adjustment in each zone.

[0115] The flakes were introduced into the main hopper (before Z1). Clariant's chemical blowing agent HYDROCEROL PEX 5048 was introduced into Z4 using a weighing dispenser. A total flow rate of 3 kg / h was obtained, yielding an extruded composition (S1) containing 4% CFA based on the total weight of the composition. The screw speed was set to 200 rpm.

[0116] b. Citric acid as CFA Crushed, washed, and colored flakes, having an average crystallinity of 34.5% and containing 98% PET, were dry-blended with 1% by weight of citric acid in powder form (Adeka Orgater exp 141 / 183) based on the total weight of the composition to obtain an extruded foam composition (S1 BIS). The screw speed was set to 110 rpm and the total flow rate to 4 kg / h.

[0117] Table 1 shows the temperature profiles along the screw for the preparation of samples S1 and S1 BIS.

[0118] [Table 1]

[0119] The molten polymer reached a screw head (Z10) equipped with a die plate having a single 3.5 mm hole, and was immediately immersed in a 2 m long cold water bath (10°C). The resulting extruded material was granulated into 2-3 mm solid pellets (samples S1 and S1 BIS). The crystallinity levels were 0% and 1%, respectively.

[0120] Porosity ε of each sample T This was calculated using the following equation.

number

number

number

[0121] Porosity ε of S1 T The percentage for the first group is 33.6%, and for S1 BIS, it is 54.6%.

[0122] The specific gravity bottle method is determined using 4 to 5 extruded pieces, each 1 to 2 cm long and corresponding to 1 to 2 g of material, as defined in the description.

[0123] The control sample "Control-1" was extruded and granulated under the same conditions as S1 without the use of a foaming agent. Control-1 has a porosity ε of 0. T It has [the characteristic]. Control-1 has a crystallinity level of 15%.

[0124] A second control sample, "Control-2" (in fine powder form), having a crystallinity level of 15%, was prepared by immersing the Control-1 pellet in liquid nitrogen and then pulverizing the pellet using a RETSCH ZM 200 Ultra-Centrifugal Mill with a 500 μm grid. Only powder particles smaller than 500 μm, obtained by sieving, were used in the depolymerization process.

[0125] B) Depolymerization process of foamed plastic products The depolymerization process was carried out in a 500 ml mini bioreactor (Global Process Concept, France) using a mutant of LC-cutinase (Sulaiman et al., Appl Environ Microbiol. 2012 Mar). This mutant (LCC-ICCIG), corresponding to the enzyme with SEQ ID No. 1 possessing the following mutations F208I+D203C+S248C+V170I+Y92G, was expressed as a recombinant protein in Trichoderma reesei.

[0126] 100 mg of LC-cutinase variant, prepared in 224 ml of 100 mM potassium phosphate buffer (pH 8), was combined with a 56 g PET sample. The temperature was adjusted to 60°C, and stirring was limited to a constant 250 rpm using a marine turbine. The pH was adjusted to 8 with 6N NaOH, and NaOH consumption was recorded during the process using a GX controller with C-BIO® software (Global Process Concept, France).

[0127] The depolymerization rate of PET was measured by periodic sampling. The samples were analyzed by ultra-high-performance liquid chromatography (UHPLC) according to the method described herein, and the amount of terephthalic acid equivalent produced was measured.

[0128] The AT equivalent concentration was determined by chromatography (UHPLC). If necessary, the sample was diluted with 100 mM potassium phosphate buffer (pH 8). 1 mL of the 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 the sample was injected into an Ultimate 3000 UHPLC system (Thermo Fisher Scientific, Waltham, MA) including a pump module, autosampler, 25°C temperature-controlled column, and 240 nm UV detector. Terephthalic acid (AT) and the produced molecules (MHET and BHET) were separated at 1 m / min using a methanol gradient (30% to 90%) in 1 mM H2SO4 through an HPLC Discovery HS C18 column (150 mm × 4.6 mm, 5 μm) equipped with a pre-column (Supelco, Bellefonte, PA). AT, MHET, and BHET were measured according to calibration curves created from commercially available AT and BHET, as well as MHET synthesized in-house. The AT equivalent is the sum of the measured terephthalic acid and the terephthalic acid equivalents in the measured MHET and BHET. The hydrolysis rates of sample S2 and control 2 were calculated based on the total amount of terephthalic acid equivalent (TA + MHET + BHET) at a given time point versus the total amount of terephthalic acid determined in the initial sample. The depolymerization rates are shown in Table 2 below.

[0129] [Table 2]

[0130] The results show that, firstly, the foaming process enables a 30-fold improvement in the depolymerization rate of PET compared to non-foamed plastic products. Furthermore, the results show that the foamed plastic product depolymerizes faster than the non-foamed, extruded, and pulverized plastic composition (control-2), indicating that the method of the present invention makes it possible to suppress the pulverization process.

[0131] Example 2 - A method for decomposing plastic products, including PET, including a foaming process using a physical foaming agent. A) Foaming process using carbon dioxide (CO2) and subsequent cooling process Washed and colored flakes from bottle waste containing 98% PET were foamed using supercritical CO2 in a single-screw extruder. This extruder (30mm diameter - SCAMEX, FRANCE) features six heating zones (T), each with independently controlled and regulated temperatures. T1 and T2: Zones before CO2 injection. T3 and T4: Zones after CO2 injection, T5: Mixing zone equipped with a static mixer, and A die plate equipped with an outlet pressure adjustable opening with a maximum opening of T6:3mm.

[0132] The temperatures at T1 to T3 were fixed at 180°C, 280°C, and 260°C, respectively, and the temperatures at T4 to T6 are listed in Table 3 below. The screw speed was fixed at 40 rpm.

[0133] The pressure at the end of the mixing zone (T5) was measured using a pressure sensor and is shown in Table 3 (P4). CO2 was pressurized and injected at a constant flow rate between T2 and T3 using a syringe pump (Isco 260D, USA). CO2 pressure, temperature, and volume input (Q) were measured. CO2 The values ​​were measured in the pump and are shown in Table 3.

[0134] The obtained extruded material was immediately immersed in fresh water at approximately 15°C, and then cut into 2-3 mm pieces using a knife mill. The resulting samples were then dried under ambient conditions for 48 hours and analyzed.

[0135] Table 3 below shows the other experimental conditions used for sample preparation, as well as the results for porosity and crystallinity. Qp is the polymer flow rate determined by weighing the obtained sample. CO2 This is the volumetric flow rate of injected CO2. Total flow rate (w CO2The mass flow rate of CO2 relative to ) is calculated using the density obtained from Span and Wagner's equation of state ((R. Span et W. Wagner, A new equation of state for carbon dioxide covering the fluid region from the triple-point temperature to 1100 k at pressures up to 800 mpa. Journal of Physical and Chemical Reference Data, vol.25(6), pp.1509-1596, 1996). Tmat is the material temperature measured at the extruder outlet.

[0136] [Table 3]

[0137] B) Nitrogen (N 2 ) foaming process and subsequent cooling process The extrusion-foaming process was carried out using a single-screw extruder (45 mm diameter, FAIREX) equipped with a melt cooler, static mixer, and a vertical die with a nominal diameter of 2 mm. Supercritical N2 was introduced using a PROMIX injection gas system. The extruded material was cooled using a 2 m long cold water bath (9°C) and then granulated with a rotary cutter to obtain pellets with a length of 1.5 mm. The distance between the die outlet and the water surface was approximately 5.5 cm.

[0138] Washed and colored flakes from bottle waste containing 95% PET (crystallinity 43%) were dried at 80°C. The set temperature and recorded material parameters are shown in Tables 4 and 5, respectively.

[0139] The screw speed was set to 25 rpm. The total material flow rate was 6 kg / h, and the injected nitrogen flow rate was 15 g / h. The resulting pellet S6 was then dried at ambient temperature for 48 hours and subsequently analyzed.

[0140] [Table 4]

[0141] [Table 5]

[0142] The obtained sample S6

number

[0143] C) Depolymerization process The same secreted recombinant LCC-ICCIG enzyme as in Example 1 was used for subsequent depolymerization of samples S2-S6 and control-1 (prepared in the same manner as in Example 1). 100 mg of each sample from S2-S6 and control-1 was weighed and introduced into a 250 ml glass vial containing 49 mL of 0.1 M potassium phosphate buffer (pH 8). After adding 1 mL of enzyme solution at a concentration of 0.1 mg / mL to 0.1 M potassium phosphate (pH 8), depolymerization was initiated by incubating each sample in a Multitron pro (Infors HT, Switzerland) at 60°C and 150 rpm.

[0144] The depolymerization rate of PET was determined by periodic sampling, and the samples were analyzed by ultra-high-performance liquid chromatography (UHPLC) to measure the amount of terephthalic acid equivalent produced according to the method described in Example 1. The hydrolysis rates of samples S2-S6 and control-1 were calculated based on the total amount of terephthalic acid equivalent (TA+MHET+BHET) at a given time point versus the total amount of terephthalic acid determined in the initial sample. The results of the depolymerization rates are shown in Table 6 below.

[0145] [Table 6]

[0146] The decomposition process of PET-containing plastic products that have been pre-foamed using a physical foaming agent (carbon dioxide or nitrogen) is 3 to 8 times more efficient than that of plastic products that have not been foamed.

[0147] Example 3 - A method for decomposing a plastic product containing PET, comprising a foaming step using a physical foaming agent and a step of cooling in a bath containing an enzyme solution. A) supercritical CO 2 A foaming process and a subsequent cooling process. Washed and colored flakes from bottle waste containing 98% PET were foamed using supercritical CO2 according to Example 2-A.

[0148] Two samples, S7 and S8, were prepared according to the instructions detailed in Table 7. The extruded material was immersed in either water (S7) or enzyme bath water (S8) containing the same secreted recombinant LCC-ICCIG enzyme as in Example 1 at approximately 4.3 g / l. The resulting extruded material was rinsed with water, dried under ambient conditions, and then cut into 2-3 mm pieces using a knife mill.

[0149] The experimental conditions used for sample preparation, as well as the results for porosity and crystallinity, are shown in Table 7 below.

[0150] [Table 7]

[0151] B) Depolymerization process Except for testing S8 without adding the enzyme to the buffer, depolymerization of S7 and S8 was carried out in glass bottles as detailed in Example 2-B. The results of the depolymerization are shown in Table 8.

[0152] [Table 8]

[0153] The decomposition process of PET-containing plastic products subjected to depolymerase during the cooling process shows a slight improvement in decomposition compared to those exposed to depolymerase only during the depolymerization process.

[0154] Example 4 - A method for decomposing a plastic product containing PLA, comprising a foaming step using a chemical foaming agent and a step of cooling in a bath containing an enzyme solution. A) Foaming process using chemical foaming agents Polylactic acid (PLA) 4043D (in pellet form from NatureWorks - 35% crystallinity) was foamed using a Leistritz ZSE 18 MAXX twin-screw extruder. This extruder features nine consecutive heating zones (Z1-Z9) and a head (Z10), allowing for independent temperature control and adjustment in each zone. A chemical blowing agent (CFA) HYDROCEROL BIH 40 masterbatch, supplied by Clariant, was used.

[0155] PLA and CFA were dried in a desiccator at 60°C and 45°C, respectively, for 14 hours. A dry blend of 95% by weight PLA pellets and 5% CFA masterbatch was added to the hopper of a weighing feeder and introduced into an extruder. A total flow rate of 2 kg / h was obtained. All temperature profiles along the screw are shown in Table 9. The screw speed was set to 100 rpm.

[0156] [Table 9]

[0157] The molten polymer reached a screw head (Z10) equipped with a die plate having a single 3.5 mm hole. The resulting extruded material was immediately immersed in a container containing 1 L of 16 L of commercially available Novozymes enzyme solution Savinase® (known to be able to decompose PLA) (at 15°C), and then manually pulled and wound up. After 24 hours, the sample was washed with water and dried for 48 hours under ambient conditions (20°C and 40% humidity). The sample was then granulated into 2-3 mm solid pellets (S9) (crystallinity 2%) using a rotary cutter. As a control, another sample (S10) was foamed in the same manner, except that the resulting extruded material was immersed in water from which the enzyme had been removed. Both S9 and S10 exhibited a crystallinity of 2% and porosity of 30% and 40%, respectively.

[0158] B) Depolymerization process 100 mg of each alloy was weighed and introduced into a cellulose dialysis tube. This was then introduced into a glass vial containing 50 mL of 100 mM Tris buffer (pH 9.5) and incubated at 45°C and 150 rpm.

[0159] The degradation rate of the alloy was measured by UHPLC according to the following protocol. 1 mL of sample was taken periodically. After filtration on a 0.22 μm filter, the sample was fed into a UHPLC system (Ultimate 3000 UHPLC system (Thermo Fisher Scientific, Inc., Waltham, MA, USA)) including a pump module, autosampler, column oven temperature-controlled to 50°C, and UV detector at 210 nm, to monitor the release of lactate and lactate dimers. Lactate and lactate dimers were extracted using an Aminex HPX-87H column and a 5 mM H2SO4 mobile phase at a rate of 0.5 mL·min. -1 Separation was performed at the specified flow rate. A 20 μL sample was injected. Lactic acid (LA) and lactic acid dimer (DP2) were measured using commercially available lactic acid (Sigma-Aldrich L1750-10G) and our company's synthesized lactic acid dimer, according to a calibration curve prepared under the same conditions as the sample.

[0160] The degradation rate was calculated according to the following molar ratios of the theoretical LA initially contained in the PLA, the LA at a given time point, and the LA contained in DP2.

[0161] After 24 hours, S9 showed a 76% degradation rate, while S10 did not clearly show degradation. The results indicate that during the cooling phase, the enzyme was immobilized within the cell structure of the foamed plastic material containing PLA.

[0162] Example 5 - Method for disassembling PET-containing textile products, including a foaming process using a chemical foaming agent. A) Foaming process for textile products containing PET Textile waste (used clothing) made of PET was sorted, shredded, washed to remove metal and hard contaminants (e.g., zippers or buttons), and compressed to obtain 2-4 mm sized textile granules containing 85% by weight of PET.

[0163] Using the same extruder, cooling, and granulation equipment as in Example 1, foamed pellets were prepared from the PET fabric granules.

[0164] Compressed textile granules were introduced into the main hopper (before Z1). Citric acid (Adeka Orgater exp 141 / 183) was used as CFA and introduced into Z4 using a weighing feeder. The screw speed was set to 110 rpm. A total flow rate of 4 kg / h was obtained, yielding an extruded composition (S11) containing 1% by weight of citric acid based on the total weight of the composition.

[0165] A control sample from the used clothing composition "Control-3" was extruded without the use of a foaming agent, cooled, granulated, and then immersed in liquid nitrogen before being pulverized to obtain a powder with a crystallization level of 13%. The set temperature profile for extrusion is shown in Table 10. The screw speed was set to 200 rpm and the total flow rate to 4 kg / h.

[0166] A woven fabric containing 100% PET was shredded, compressed, dry-blended with 1% by weight citric acid and 0.5% by weight water based on the total weight of the mixture, and then extruded. The same extruder as for samples S11 and control-3 was used. The dry blend was introduced into the main hopper (before Z1) via a gravimetric dispenser. A total flow rate of 2.5 kg / h was obtained, yielding an extruded composition (S12) containing 1% by weight citric acid based on the total weight of the composition. The screw speed was set to 150 rpm.

[0167] The temperature profiles along the screw for samples S11, S12, and control-3 are shown in Table 10 below.

[0168] [Table 10]

[0169] S11 and S12 have crystallinity levels of 13% and 0%, and porosity levels of 25% and 36%, respectively (true density was measured in an extruded but non-foamed fabric composition).

[0170] B) Depolymerization process of foamed textile products The depolymerization process was carried out under the same conditions as in Example 1)-B.

[0171] The obtained depolymerization rates are summarized in Table 11 below.

[0172] [Table 11]

[0173] The results show that the foamed fabric product is depolymerized to the same extent as the non-foamed, extruded, and pulverized fabric composition (control-3), indicating that the method of the present invention makes it possible to suppress the pulverization process.

[0174] Example 6 - A method for decomposing a plastic product containing PET, comprising a foaming step using a chemical blowing agent and a depolymerization step using a chemical depolymerizing agent. A) Preparation of foamed plastic products In this example, the following materials were used. • Sample S1 BIS: Equivalent to crushed, washed, and colored flakes foamed with citric acid, as described in Example 1-A)b). • Sample control-1: Extruded and granulated, but non-foamed flake equivalent (see Example 1) • Control-2: Obtained by micronizing the flakes of Control-1 (see Example 1). • Control-4: Equivalent to Control-1, subjected to annealing in a 120°C oven for 48 hours to recrystallize the pellets. Control-4 shows a crystallization level of approximately 32.2%. • Control-5: Obtained by micronizing the pellets of Control-4 (using the method described in Example 1).

[0175] B) Chemical depolymerization of foamed plastic products Chemical depolymerization was carried out in 15 mL screw-cap glass tubes (Supelco, 27162). Approximately 40-50 mg of PET sample was placed in the glass tube, and a total of 800 μL of DCM and 400 μL of methanol / KOH (3M) were added. This mixture was stirred by magnetic stirring at room temperature (RT, approximately 25°C) for 5 minutes. The solvent was evaporated under a stream of N2 for 10 minutes. The PET monomer was dissolved in 14 mL of Milli-Q® water. This solution was stirred at room temperature for 5 minutes. The amount of monoethylene glycol (MEG) produced was determined by ultra-high-performance liquid chromatography (UHPLC) according to the method described herein.

[0176] 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 μm syringe filter, 20 μL of the sample was injected into an Ultimate 3000 UHPLC system (Thermo Fisher Scientific, Waltham, MA) including a pump module, automated sampler, a column temperature-controlled to 55°C, and an RI detector. MEG molecules were separated using an HPLC Aminex HPX-87H ion exclusion column (300 mm × 7.8 mm, 9 μm) equipped with a pre-column (Supelco, Bellefonte, PA). 0.8 mL of MEG was separated. -1 Elution was performed with 5 mM H2SO4 using the specified flow rate. MEG was measured according to a calibration curve prepared from commercially available MEG. The reaction rate was calculated based on the total amount of MEG at a given time point relative to the total amount of MEG determined in the first sample. The reaction rate results and the crystallization level for each sample are shown in Table 12 below.

[0177] [Table 12]

[0178] The results show that foamed plastic products depolymerize faster than non-foamed plastic products, and faster than annealed (recrystallized) pellets, with or without pulverization. Furthermore, the results show that foamed products depolymerize to the same extent as non-foamed, extruded, and pulverized products, indicating that the pulverization process can be suppressed according to the method of the present invention.

Claims

1. A method for decomposing a plastic product containing at least one polymer, a. A process of foaming a plastic product at least partially, b. A step of depolymerizing at least one target polymer of a plastic product that is at least partially foamed, wherein the target polymer is polyethylene terephthalate (PET) or polylactic acid (PLA), and the depolymerization step includes contacting the plastic product with a biological depolymerizing agent which is an enzyme. The foaming process is carried out at a temperature in which the plastic product is partially or entirely molten, and The process further includes a step of cooling a partially foamed plastic product within 30 seconds after the foaming process by subjecting the plastic product to a temperature below the crystallization temperature (Tc) of the target polymer. method.

2. The method according to claim 1, wherein the foaming process is carried out at a temperature higher than the crystallization temperature (Tc) of the target polymer.

3. The method according to claim 1, wherein the foaming process is carried out using a gaseous physical foaming agent.

4. The method according to claim 3, wherein the gas is selected from the group consisting of nitrogen, carbon dioxide, methane, helium, neon, argon, xenon, hydrogen, or mixtures thereof.

5. The method according to claim 1, wherein the foaming process is carried out using a chemical foaming agent.

6. Chemical blowing agents include: - Selected from the group consisting of citric acid, carbonate, bicarbonate, or mixtures thereof, - A mixture of citric acid and bicarbonate The method according to claim 5, which is any of the following.

7. The method according to claim 1, wherein the plastic product that is at least partially foamed exhibits a porosity of more than 20%.

8. The method according to claim 1, wherein after the cooling step, the polymer exhibits a crystallinity of up to 30%.

9. The method according to claim 1, wherein a plastic product that has been at least partially foamed is subjected to a granulation step between a cooling step and a depolymerization step.

10. The method according to claim 1, wherein the foaming process is carried out in an extruder or an autoclave.

11. The method according to claim 1, wherein the enzyme is selected from the group consisting of a depolymerase, a depolymerase capable of degrading at least one polymer of a plastic product, and a depolymerase capable of degrading at least a target polymer of a plastic product.

12. The method according to claim 1, wherein the foaming step is carried out using a chemical foaming agent, and the enzyme is a depolymerase capable of degrading at least the target polymer of the plastic product.

13. A method for decomposing plastic products, including at least PET, a. A process of foaming a plastic product at least partially with a chemical foaming agent, wherein the foaming process is carried out at a temperature exceeding 170°C, b. A step of cooling the at least partially foamed plastic product at a temperature of less than 100°C after the foaming process, c. A step of depolymerizing a cooled PET plastic product by contacting the cooled plastic product with a biological depolymerizing agent which is an enzyme, and optionally, The process involves recovering the oligomers and / or monomers generated by the depolymerization of the PET and selectively purifying them. A method that includes [this].

14. The method according to claim 13, wherein the chemical blowing agent is selected from citric acid, carbonates, bicarbonates, and mixtures thereof.

15. The method according to claim 13, wherein a plastic product that has been at least partially foamed is subjected to a granulation step between a cooling step and a depolymerization step.

16. The method according to claim 13, wherein the enzyme is a depolymerase or an esterase.

17. A method for producing monomers and / or oligomers and / or degradation products from a plastic product containing at least one polymer, A method comprising subjecting a plastic product to a foaming step, a cooling step, and subsequently a depolymerization step by exposing the foamed plastic product to a depolymerase, wherein the polymer is PET or PLA.

18. A method for decomposing at least partially foamed plastic products containing at least one polymer, A method comprising contacting a partially foamed plastic product with an enzyme capable of decomposing at least one polymer of the plastic product, wherein the partially foamed plastic product is obtained from plastic waste and / or textile waste that has already been subjected to a foaming and cooling step, and the polymer is PET or PLA.

19. The method according to claim 18, wherein the polymer of the at least partially foamed plastic product is already amorphous before contact with the enzyme.

20. A method for recycling plastic products selected from plastic waste and / or textile waste containing at least one polymer, A method comprising the step of depolymerizing the plastic product by contacting the plastic product with an enzyme, wherein the plastic product is already at least partially foamed and cooled, and the polymer is PET or PLA.

21. The method according to claim 20, wherein the polymer of the plastic product is already amorphous.

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