Chemical Products – Marie-Laure Desrousseaux, Helene Texier, Sophie Duquesne, Alain Marty, Mediha Aloui Dalibey, Michel Chateau, Carbios SA

Abstract for “Process to degrade plastic products”

“The invention concerns processes for degrading plastics and their uses. The invention includes a step for amorphizing a product before it is depolymerized. The invention is particularly useful in degrading plastic products made of polyethylene terephthalate or polylactic acid. The invention also covers a method for producing monomers and/or Oligomers from a product that contains at least one polyester, especially polyethylene terephthalate, and/or polylactic acids. This involves submitting the product to both an amorphization and a depolymerization steps.

Background for “Process to degrade plastic products”

Plastics are durable and inexpensive materials that can be used in a wide variety of products. The production of plastics has risen dramatically in the past decade. Plastics used in disposable, single-use applications such as packaging, agricultural films, consumer products, and disposable items are more than 50%. Due to the high durability of these polymers, large quantities of plastics pile up in landfills and natural habitats around the world, creating environmental problems. Degradable and biodegradable materials can last for decades, depending on the local environment factors like temperature, ultraviolet light exposure, temperature, presence or absence of suitable microorganisms, among others.

“There are many ways to reduce the environmental and economic impact of plastic accumulation, including plastic degrading, plastic recycling, and reprocessing plastics in new materials.

“Polyethylene Terephthalate (PET), an aroma polyester made from terephthalic Acid and ethylene glycol has been used in many products for human consumption in recent years. Bottles, convenience-sized soft drinks and pouches for alimentary products, as well as textiles, fabrics, carpets, and rugs.

PET is the most closed-loop, recycled plastic. In general, PET wastes undergo successive treatment that leads to recycled PET (rPET). PET waste (mainly bottles) is collected, sorted and pressed into bales. Then, they are washed and chopped into flakes. Finally, pellets are melted and extruded into pellets for sale. These PET can then be recycled to make fabrics or new packaging, such as blister packs or bottles.

However, these plastic recycling processes can only be used for PET-containing plastics and require extensive sorting. These plastic recycling methods are expensive and can lead to downgrading of products. They are also more costly than virgin plastic, which means that recycled products are not competitive with virgin plastic.

Chemical recycling is another option for plastic recycling. This allows the polymer’s chemical constituents to be recovered. After purification, the monomers can be used to make synthetic chemicals or re-manufacture items made of plastic. This recycling process is currently only applicable to sorted or partially-sorted polymers. It does not work well with raw plastic products which may contain a mixture of polymers.

“There is a need for a better process to degrade plastic products, which does not require expensive pretreatments or preliminary sorting. This can be used to increase industrial yield.”

The present invention provides new methods of degrading polyester-containing plastic products. It includes a step for amorphizing the product and a step for depolymerization. The amorphization step is advantageous because it allows for a decrease in the crystallinity of the polyester and favors subsequent polymerization. Combining amorphization with depolymerization allows for high levels of degradation without the need to sort or under industrial conditions. These methods are especially useful in the degrading of plastic products that contain polyethylene terephthalate.

“In this respect, it is the object of the invention provide a method for degrading plastic products containing at least one polymer, which includes the following steps:

“a. Amorphizing at minimum partially at least one polyester from the plastic product; and

“b. Depolymerizing meant at least partially amorphized polyester in the plastic product.”

“It is another object of this invention to provide a method of producing monomers/or oligomers out of a plastic product containing at minimum one polyester. This involves submitting the product to an amorphization stage to amorphize at most partially a polyester of plastic product and then to a subsequent step of depolymerization to depolymerise the at least partially-amorphized polyester of plastic product. The invention describes the depolymerization as a biological process where the plastic product is exposed at least partially to a polymerase.

“It is also an object of the invention that a method for recycling plastic products comprising at least one Polyester be provided, which includes subjecting successively said at most one polyester to depolymerization and amorphization, and recovering monomers or oligomers.”

“It is also the object of the invention, to provide a method of treating a plastic product consisting at least one polyester. The plastic product is subject to amorphization or depolymerization.”

“In one embodiment, the amorphization process involves exposing the plastic product to a temperature higher than the crystallization temperature Tc and preferably above the melting temperatures Tm of a polyester plastic product.”

“In addition to the amorphization process, the plastic product is subjected to shear stress. A particular embodiment of the amorphization process includes heating the product and submitting it to a temperature below Tg (the glass transition temperature) of the polyester.

“In one embodiment, the process includes a biological depolymerization step in which the plastic product is contacted by a depolymerase or a microorganism that expresses and excretes a depolymerase. The depolymerase can be selected from cutinases or lipases, protases, carboxylesterases, esterases and/or microorganisms. Preferably, cutinases or proteases.

“It is, therefore, an object of the invention that a method for degrading plastic products containing at least one polymer be provided. It comprises the following steps:

“The plastic product should contain semi-crystalline polyesters, and preferably polyethylene Terephthalate and/or lactic acid.

“It is another object of the invention that a method for degrading PET-containing plastic products can be provided. It includes the following steps:

“a. Amorphizing at most partially PET of the plastic material; and

“b. Depolymerizing PET for the plastic product”

“These and other embodiments and objects of the invention will be more apparent after the detailed description, including the preferred embodiments thereof, of the invention.”

“LEGEND TO THOUGHTS”

“FIG. 3: Depolymerization before and after an amorphization step according the invention (MB2,,MB3, and MB4). The initial rate for enzymatic polymerization of amorphized milk bottles MB3, MB2 or MB4 was 3.2, 4.6, and 10 times faster than non-treated milk bottles (sample: MB1). The reaction was completed with 86%, 88%, and 89% respectively of the amorphized samples (MB3, MB2 & MB4) being enzymatically reduced, while only 33% of the crystalline milk bottle sample (MB1) were.

“FIG. 4. Depolymerization Cristaline Water bottles before (CB1), and after (CB2) amorphization according the invention. The reaction ended with 90.5% of amorphized Cristaline. Bottle sample CB2 was enzymatically broken down, while only 18% of crystal Cristaline was? Bottle sample CB1 was enzymatically broken down.”

“Definitions”

The following definitions will help you to understand the present disclosure better.

“In the context of the invention, terms such as?plastic article?? “plastic article” or “plastic product?” They are interchangeable and can be used to refer to any item of product that contains at least one polymer. These include plastic sheets, tubes, rods, profiles, shapes, massive blocks, fibers, etc. The plastic article should be manufactured, including rigid or flexible packaging and bags and sacks, disposable products or the like, carpet scrap, fabrics or textiles. Additional substances or additives may be added to the plastic article, including plasticizers and minerals, organic fillers, dyes and dyes. The plastic article could contain a mixture of semi-crystalline, amorphous and/or amorphous Polymers and/or Additives.

“A ?polymer? A chemical compound or mixture made up of many repeating units is called a “polymer”. ?monomers?) covalent chemical bonds. The term “polymer” is used in the context of the invention. The term “polymer” can be used to refer to natural or synthetic polymers. It may include a single type (homopolymers), or multiple types (block copolymers or random copolymers) of repeating units. Synthetic polymers, for example, are polymers made from petroleum oil. They include polyolefins as well as aliphatic and aromatic polyesters, polyamides polyurethanes, polyamides, and polyvinylchloride. Natural polymers include lignin, polysaccharides, such as cellulose, hemi-cellulose, starch, and polyhydroxyalkanoates and derivatives thereof.”

According to the invention, “oligomers” means molecules containing between 2 and 20 monomer units. “Oligomers” are molecules that contain between 2 and 20 monomer units. As an example, oligomers retrieved from PET include methyl-2-hydroxyethyl terephthalate (MHET) and/or bis(2-hydroxyethyl) terephthalate (BHET) and/or 2-hydroxyethyl benzoate (HEB) and/or dimethyl terephthalate (DMT). Another example is the possibility of retrieving oligomers from PLA.

“In the context of the invention, ‘polyester? refers to a polymer that contains the ester functional group in their main chain. A polymer that contains the ester functional groups in its main chain. The ester functional group is defined by a carbon that is bound to three other molecules: a single, double, or single bond to a carbon. A single-bound oxygen is bound to another carbon. Polyesters can be either aromatic, semi-aromatic, or aliphatic depending on the main chain. Polyester can be either homopolymer, copolymer, or both. Polyethylene terephthalate, for example, is a semi-aromatic copolymer made of two monomers: terephthalic Acid and ethylene glycol.

“In the context the invention,?crystalline polmers? Or?semicrystalline polymers? These are partially crystalline polymers in which crystalline and amorphous regions coexist. Semi-crystalline polymers can be evaluated using different analytical methods. Typically, the range is between 10 and 90%. Differential Scanning calorimetry or X-Ray diffraction can be used to determine the crystallinity of certain polymers. For estimating polymer crystallinity with lower reliability, other techniques such as Small Angle X-ray Scattering and Infrared Spectroscopy are also available. The levels of crystallinity described in the current disclosure correspond to the DSC-measured crystallinity. Particularly, DSC experiments were performed as follows: A small amount of the sample (several milligrams) was heated at a constant heat rate from ambient temperature or sub-ambient to a temperature higher than the Tm for polyester. The heat flow data are collected and plotted against the temperature. The following formula is used to calculate the degree of crystallinity (Xc):

“?Hf” is the enthalpy for melting, which can be calculated by integrating an endothermic melt peak.

“?Hcc” is the enthalpy for cold crystallization. It can be calculated by integrating the exothermic peak of cold crystallization.

“wt the weight fraction polyester in the plastic”

“?Hf.100%” is the melting enthalpy for fully crystalline polymers and can be found in literature.

“As an illustration,?Hf.100% of PET can be taken from literature at 125.5 J/g. (Polymer Data Handbook Second Edition, Edited By James E. Mark. OXFORD 2009). According to literature,?Hf.100% of PLA equals 93 J/g. (Fisher E. W. Sterzel H.J., Wegner G. Investigation of the structure solution grown crystals lactide copolymers using chemical reactions, Kolloid Zeitschrift & Zeitschrift fur Polymere 1973, 251, p 980-990).

“Amorphization” and “amorphization” are used herein. or ?amorphizing? Amorphizing and?amorphizing? are interchangeable terms that refer to a step that decreases the crystallinity of a polymer relative to its crystallinity prior to the amorphizing process. The amorphizing process allows for a decrease in crystallinity by at least 5%. The amorphization step in the invention leads to a polymer in a plastic product that has at least 30%, preferably at maximum 25%, more preferably, at most 20%, and even more preferably, at most 15% crystallinity. The amorphization step is preferred because it reduces the crystallinity by at least 5% or 10%, 20%, 30% and 40%, respectively, as compared to the level of crystallinity prior to the amorphizing process. This results in a polymer that has at most 25%, preferably at maximum 20%, more preferably at maximum 15% crystallinity.

“A ?degrading process? A process where at least one of the polymers in a plastic article is broken down into smaller molecules such as monomers or oligomers and/or carbon dioxide.

“In the context the invention,?”Tg??,?Tc??,?Tccc? and?”Tm???????????????????????????????” respective refer to the glass transition temperature or the crystallization temp and the melting point of a polymer. These temperatures can be calculated using different analytical methods that are well-known to those skilled in the art. Differential scanning calorimetry (DSC), or differential thermal analysis (DTA), may be used to determine the Tg,Tc, Tccc and Tm of polymers. The temperatures of Tg,Tc,Tcc and Tm of the polymers described in this disclosure correspond to those measured using DSC.

“Amorphization Step”

“Inventors have demonstrated that it is possible improve the degradability a plastic product made up of polyesters by subjecting the product to conditions favoring the amorphization of a particular polyester before a depolymerization thereof.” The plastic product can be amorphized to remove at least part of its crystalline structure.

“In one embodiment, the amorphization process involves exposing the plastic product to temperatures at which it is partially or completely molten.”

The invention allows for the use of different polyesters in the plastic product. The plastic product can be advantageously exposed to temperatures at or above Tc or Tm of the target Polyester, i.e. For which depolymerization is planned. Alternativly, the plastic product can be exposed to temperatures at or above Tc or Tm for the polyesters. This may result in the amorphization all polyesters contained within the plastic product.

“In one embodiment, the plastic product also contains thermoplastic polymers other that a polyester. The plastic product can be subjected to temperatures at or above Tc, Tm, or higher than the Tc and Tm of target polyesters, or to temperatures above the highest Tc, Tm, or Tc of thermoplastic polymers in the product.

A skilled person in the art can adjust the temperature of the amorphizing process to suit the target polyester. The plastic product must be heated for a sufficient time to achieve amorphization. Depending on temperature and/or plastic product, this time period could be between 10 seconds to several minutes.

“A preferred embodiment of the amorphization process involves submitting the plastic product to both shear stress and temperature. Preferably, this is at or above Tc of a polyester. To increase amorphization, heating and shear stress should be performed simultaneously.

“In one embodiment, the step for amorphizing may also include cooling the plastic product after heating it. This is to set the plastic product in the amorphized state. The cooling can be done immediately after heating.

“In one embodiment, cooling is achieved by heating the heated plastic product at a temperature below Tg of a polyester.

“In one embodiment, the plastic product is subjected to cooling temperatures subsequently to heating. Preferably, less than 30 seconds. More preferably, less than 20 seconds. Even more preferable, less than 10 seconds.

“Alternatively, you can cool the product by placing it in cold air. Another option is to cool such article with cooling air.

“More generally, any method that can rapidly reduce the temperature of the plastic product could be used.”

“In one embodiment, the process of amorphizing further includes adding at least one degradation agent. Water, monomers and alcohol are all examples of degrading agents. These degrading agents are best added during the heating and/or shear stress phases of the plastic product.

“Preferably, the step that is used to amorphize the plastic product includes at least water addition. Monomers of a polyester are also added to the product during amorphization. Monomers should be selected from monomers in the target polyester (i.e. For which a depolymerization of the monomers is desired. A particular embodiment adds monomers of PET, such as monoethylene glycol and/or Terephthalic Acid and/or Isophthalic Acid, during the step for amorphizing a PET-containing plastic article. These monomers are particularly useful during the heating phase.

“Preferably, these degrading agents should be added at a concentration lower than 20% of the total weight (i.e. “Plastic product and degrading agent) are added at a concentration below 20% of the total mass (i.e., less than 0.05%) before being submitted to the amorphization phase. Another embodiment adds such degrading agents at a concentration of 0.1 to 10%, and more preferably between 0.01 and 5% before the amorphization step.

“In one embodiment, water is added to the heated phase of the plastic article at a concentration greater than 5%, preferable between 10 and 20%. Monomers can also be added to the plastic article’s heating phase at a concentration lower than 10%, preferably below 5% or 4%, and 2%, respectively.

“In one embodiment, the extruder is used to perform the amorphization process. An extruder can be used to simultaneously or sequentially submit a plastic product to both a specific temperature and shear stress. If necessary, the extruder can also be used to add degrading agents. Further, the extruder can cool the plastic product. To achieve the amorphization process, an extruder may be used. This includes single-screw or multi-screw models, dispersive and reciprocating single-screw, co-rotating or counter rotating designs, internal mixers, mini extruders, and mini extruders. An underwater pelletizer that produces mini pellets less than 1 mm is preferred to be attached to the head of an extruder. This will allow for the production of plastic pellets of desired size and replace the step of grinding before depolymerization.

“Amorphization” can also be achieved by any process that allows to break at minimum partially the crystal structure of at least one polyester in the plastic product.

“Alternatively, the step of amorphization can be performed in a reactor or via atomization or solubilization in a solvent or electronic or atomic radiation or cryogenic mechanical atrition (Schexnaydre and al., 2008). Or any other techniques that are known to a person who is skilled in the art.

“Depolymerization Step”

According to the invention, the process of degradation includes, after the amorphizing step is completed, a step depolymerization. Preferably, the depolymerizing steps targets at least one polyester that was targeted by the previous amorphizing step.

“The depolymerizing steps may include a chemical and/or biological depolymerization. Preferably, at least a biologic depolymerization.”

According to a particular embodiment, the process of degrading the invention involves contacting the plastic product using a depolymerase (i.e. an enzyme). The depolymerase should be able to degrade at most one polyester from the plastic product. Preferably, it must also be able to degrade any polyester that has been previously modified by the amorphizing process.

“The depolymerase is advantageously selected from the group consisting of a cutinase, a lipase, a protease, a carboxylesterase, a p-nitrobenzylesterase, an esterase, a scl-PHA depolymerase, a mcl-PHA depolymerase, a PHB depolymerase. A particular embodiment of the invention involves contact with at least two different types depolymerases.

“In a particular embodiment, PET is used as the plastic product. The depolymerase is preferably selected from Thermobifida Cellulosityca or Thermobifida halotolerans. Another embodiment uses a metagenomic database such as LC?Cutinase, described in Sulaiman et. al. (2012) or any functional variant thereof. Another embodiment of the depolymerase includes a lipase that is preferably made from Ideonella sakaiensis. Another embodiment of the depolymerase is a cutinase from Humicola Insolens. Another embodiment uses commercial enzymes like Novozym51032 or any functional variation thereof as the depolymerase.

The enzyme can be either in soluble or solid phase, such as powder. It may also be bound to cell membranes and lipid vesicles or synthetic supports like glass, plastic, polymers or filter membranes. It can be isolated or purified. The invention prefers that the enzymes are expressed, derived from, secreted or isolated from microorganisms. The enzymes can be purified using techniques that are known in the art and stored according to conventional methods. You can modify the enzymes to increase their activity, stability and/or adsorption onto the polymer. The enzymes may contain stabilizing or solubilizing ingredients, such as water and/or glucoserol, sorbitol and dextrin (including maltodextrine/cyclodextrine), starch, propanol, salt, and others.

“Another embodiment involves the contact of the plastic product with a microorganism which expresses and excretes depolymerase. The invention allows the enzyme to be expelled from the culture medium, or toward the cell membrane of the microorganism in which it may be anchored. The microorganism could naturally synthesize depolymerase or it may be a synthetic microorganism that has been modified to insert a recombinant nucleotide sequence, such as a vector, into which the depolymerase is encoded. A vector is an example of a nucleotide molecular encoding depolymerase. plasmids, recombinant viruses, episomes, artificial chromosomes, and the like. The art of transforming the host cell and providing suitable culture conditions for it are well-known to those who are skilled in this field.

“Recombinant microorganisms can be used directly. You can also purify recombinant enzymes from the culture media. Any commonly used separation/purification means, such as salting-out, gel filtration, hydrophobic interaction chromatography, affinity chromatography or ion exchange chromatography may be used for this purpose. Particularly, microorganisms that are capable of synthesizing and excreting depolymerases may be used.

“Accordingly to the invention, multiple microorganisms and/or purified and/or synthetic enzymes can be used simultaneously or sequentially in order to depolymerize different types of polymers contained within a single plastic article or in other plastic articles.”

“The microorganisms of the invention have a modified metabolism to avoid the consumption of monomers and/or the oligomers derived from degraded polymers. The microorganism may be a recombinant microorganism in which the enzymes that degrade monomers and/or Oligomers have been removed or eliminated. Alternately, the invention can be carried out in a medium that contains at least one carbon source so that the microorganism prefers to consume this carbon source over monomers or oligomers.

“Advantageously, the plastic articles are contacted with a culture media containing microorganisms and glucose as a carbon source as well as an existing nitrogen source (e.g. peptone or meat extract, yeast extract or corn steep liquor) or an organic nitrogen source such as ammonium sulfurate or ammonium chloride. The culture medium can also contain inorganic salts, such as sodium ion and potassium ion. The medium can also contain trace components like vitamins and amino acids.

“In one embodiment, depolymerase may be used in conditions that favor its adsorption onto the plastic article. This allows the polymer of a plastic article to more efficiently be depolymerized into monomers and/or other oligomers. A depolymerase that has been modified may have a higher affinity for the polymer of a plastic particle than a wild-type enzyme. The depolymerase can also be used in combination with plastic-binding protein or binding modules to enhance the interaction between it and the polymer of a plastic article.

The time it takes to depolymerize at least one of the polymers of a plastic article can vary depending on the article and the polymer (i.e. the nature and origin of the article, its composition, shape and molecular weight, and so forth). ), the type and amount of microorganisms/enzymes used, as well as various process parameters (i.e., temperature, pH, additional agents, etc.). The temperature must be maintained below an inactivating temperatures. This is the temperature at which depolymerase can no longer be activated and/or the recombinant organism ceases to synthesize depolymerase. In one embodiment, the temperature is kept below the Tg value of the target polyester that will be depolymerized. The pH can be adjusted to improve the efficiency of the process based on several factors such as the target polyester, the solubility and/or development of coproducts. A particular embodiment adjusts the pH to maintain the optimal pH for the depolymerase. A skilled person in the art can easily modify the process parameters for plastic articles and/or polymerases.

“Additional Optional Steps.”

“In one embodiment, the degrading step may include a preliminary polymerizing step that is performed prior to the step of amorphization. It is preferred that the non-depolymerized, polymers from the preliminary depolymerising stage are removed before the step of amorphization.

“In one embodiment, the degrading step may include a pretreatment step to modify mechanically,/or physically,/or chemically,/or biologically, the said pretreatment step being performed prior to the amorphizing and/or depolymerising steps.”

“For example, pretreatment can physically alter the structure of the plastic product to increase contact between the polymers, enzymes, and/or facilitate the amorphization process. Pretreatment can also be used to reduce the microbial charges resulting from wastes.

“In one embodiment, the plastic article can be transformed into an emulsion, or a powder, and then added to a liquid medium that contains the microorganisms/enzymes. The plastic article can also be mechanically ground, granulated or pelleted. By impacting, crushing, grinding or cryogenic grinding to reduce the size of the material and/or modify its shape before it is subject to amorphization. A mechanical pretreatment could also include a sonication or centrifugation, as well as a collisop or a high-pressure homogenizer. It can also include a maceration of liquefaction using a rotary drum or screw press.

“Alternatively, or in addition, you can apply a thermal pretreatment, such as using microwaves. This thermal pretreatment can be used to sterilize, pasteurize or disinfect the plastic product.

“Another embodiment of the plastic product is chemically treated to modify its structure and increase contact between the polymers, enzymes. You can use a basic, acidic or ionic liquid as well as a solvent. You can also use ozonation.

“In some embodiments, the plastic article can also be sorted and washed before it is degraded.

“Several pre-treatments can be combined according to the invention.”

Summary for “Process to degrade plastic products”

Plastics are durable and inexpensive materials that can be used in a wide variety of products. The production of plastics has risen dramatically in the past decade. Plastics used in disposable, single-use applications such as packaging, agricultural films, consumer products, and disposable items are more than 50%. Due to the high durability of these polymers, large quantities of plastics pile up in landfills and natural habitats around the world, creating environmental problems. Degradable and biodegradable materials can last for decades, depending on the local environment factors like temperature, ultraviolet light exposure, temperature, presence or absence of suitable microorganisms, among others.

“There are many ways to reduce the environmental and economic impact of plastic accumulation, including plastic degrading, plastic recycling, and reprocessing plastics in new materials.

“Polyethylene Terephthalate (PET), an aroma polyester made from terephthalic Acid and ethylene glycol has been used in many products for human consumption in recent years. Bottles, convenience-sized soft drinks and pouches for alimentary products, as well as textiles, fabrics, carpets, and rugs.

PET is the most closed-loop, recycled plastic. In general, PET wastes undergo successive treatment that leads to recycled PET (rPET). PET waste (mainly bottles) is collected, sorted and pressed into bales. Then, they are washed and chopped into flakes. Finally, pellets are melted and extruded into pellets for sale. These PET can then be recycled to make fabrics or new packaging, such as blister packs or bottles.

However, these plastic recycling processes can only be used for PET-containing plastics and require extensive sorting. These plastic recycling methods are expensive and can lead to downgrading of products. They are also more costly than virgin plastic, which means that recycled products are not competitive with virgin plastic.

Chemical recycling is another option for plastic recycling. This allows the polymer’s chemical constituents to be recovered. After purification, the monomers can be used to make synthetic chemicals or re-manufacture items made of plastic. This recycling process is currently only applicable to sorted or partially-sorted polymers. It does not work well with raw plastic products which may contain a mixture of polymers.

“There is a need for a better process to degrade plastic products, which does not require expensive pretreatments or preliminary sorting. This can be used to increase industrial yield.”

The present invention provides new methods of degrading polyester-containing plastic products. It includes a step for amorphizing the product and a step for depolymerization. The amorphization step is advantageous because it allows for a decrease in the crystallinity of the polyester and favors subsequent polymerization. Combining amorphization with depolymerization allows for high levels of degradation without the need to sort or under industrial conditions. These methods are especially useful in the degrading of plastic products that contain polyethylene terephthalate.

“In this respect, it is the object of the invention provide a method for degrading plastic products containing at least one polymer, which includes the following steps:

“a. Amorphizing at minimum partially at least one polyester from the plastic product; and

“b. Depolymerizing meant at least partially amorphized polyester in the plastic product.”

“It is another object of this invention to provide a method of producing monomers/or oligomers out of a plastic product containing at minimum one polyester. This involves submitting the product to an amorphization stage to amorphize at most partially a polyester of plastic product and then to a subsequent step of depolymerization to depolymerise the at least partially-amorphized polyester of plastic product. The invention describes the depolymerization as a biological process where the plastic product is exposed at least partially to a polymerase.

“It is also an object of the invention that a method for recycling plastic products comprising at least one Polyester be provided, which includes subjecting successively said at most one polyester to depolymerization and amorphization, and recovering monomers or oligomers.”

“It is also the object of the invention, to provide a method of treating a plastic product consisting at least one polyester. The plastic product is subject to amorphization or depolymerization.”

“In one embodiment, the amorphization process involves exposing the plastic product to a temperature higher than the crystallization temperature Tc and preferably above the melting temperatures Tm of a polyester plastic product.”

“In addition to the amorphization process, the plastic product is subjected to shear stress. A particular embodiment of the amorphization process includes heating the product and submitting it to a temperature below Tg (the glass transition temperature) of the polyester.

“In one embodiment, the process includes a biological depolymerization step in which the plastic product is contacted by a depolymerase or a microorganism that expresses and excretes a depolymerase. The depolymerase can be selected from cutinases or lipases, protases, carboxylesterases, esterases and/or microorganisms. Preferably, cutinases or proteases.

“It is, therefore, an object of the invention that a method for degrading plastic products containing at least one polymer be provided. It comprises the following steps:

“The plastic product should contain semi-crystalline polyesters, and preferably polyethylene Terephthalate and/or lactic acid.

“It is another object of the invention that a method for degrading PET-containing plastic products can be provided. It includes the following steps:

“a. Amorphizing at most partially PET of the plastic material; and

“b. Depolymerizing PET for the plastic product”

“These and other embodiments and objects of the invention will be more apparent after the detailed description, including the preferred embodiments thereof, of the invention.”

“LEGEND TO THOUGHTS”

“FIG. 3: Depolymerization before and after an amorphization step according the invention (MB2,,MB3, and MB4). The initial rate for enzymatic polymerization of amorphized milk bottles MB3, MB2 or MB4 was 3.2, 4.6, and 10 times faster than non-treated milk bottles (sample: MB1). The reaction was completed with 86%, 88%, and 89% respectively of the amorphized samples (MB3, MB2 & MB4) being enzymatically reduced, while only 33% of the crystalline milk bottle sample (MB1) were.

“FIG. 4. Depolymerization Cristaline Water bottles before (CB1), and after (CB2) amorphization according the invention. The reaction ended with 90.5% of amorphized Cristaline. Bottle sample CB2 was enzymatically broken down, while only 18% of crystal Cristaline was? Bottle sample CB1 was enzymatically broken down.”

“Definitions”

The following definitions will help you to understand the present disclosure better.

“In the context of the invention, terms such as?plastic article?? “plastic article” or “plastic product?” They are interchangeable and can be used to refer to any item of product that contains at least one polymer. These include plastic sheets, tubes, rods, profiles, shapes, massive blocks, fibers, etc. The plastic article should be manufactured, including rigid or flexible packaging and bags and sacks, disposable products or the like, carpet scrap, fabrics or textiles. Additional substances or additives may be added to the plastic article, including plasticizers and minerals, organic fillers, dyes and dyes. The plastic article could contain a mixture of semi-crystalline, amorphous and/or amorphous Polymers and/or Additives.

“A ?polymer? A chemical compound or mixture made up of many repeating units is called a “polymer”. ?monomers?) covalent chemical bonds. The term “polymer” is used in the context of the invention. The term “polymer” can be used to refer to natural or synthetic polymers. It may include a single type (homopolymers), or multiple types (block copolymers or random copolymers) of repeating units. Synthetic polymers, for example, are polymers made from petroleum oil. They include polyolefins as well as aliphatic and aromatic polyesters, polyamides polyurethanes, polyamides, and polyvinylchloride. Natural polymers include lignin, polysaccharides, such as cellulose, hemi-cellulose, starch, and polyhydroxyalkanoates and derivatives thereof.”

According to the invention, “oligomers” means molecules containing between 2 and 20 monomer units. “Oligomers” are molecules that contain between 2 and 20 monomer units. As an example, oligomers retrieved from PET include methyl-2-hydroxyethyl terephthalate (MHET) and/or bis(2-hydroxyethyl) terephthalate (BHET) and/or 2-hydroxyethyl benzoate (HEB) and/or dimethyl terephthalate (DMT). Another example is the possibility of retrieving oligomers from PLA.

“In the context of the invention, ‘polyester? refers to a polymer that contains the ester functional group in their main chain. A polymer that contains the ester functional groups in its main chain. The ester functional group is defined by a carbon that is bound to three other molecules: a single, double, or single bond to a carbon. A single-bound oxygen is bound to another carbon. Polyesters can be either aromatic, semi-aromatic, or aliphatic depending on the main chain. Polyester can be either homopolymer, copolymer, or both. Polyethylene terephthalate, for example, is a semi-aromatic copolymer made of two monomers: terephthalic Acid and ethylene glycol.

“In the context the invention,?crystalline polmers? Or?semicrystalline polymers? These are partially crystalline polymers in which crystalline and amorphous regions coexist. Semi-crystalline polymers can be evaluated using different analytical methods. Typically, the range is between 10 and 90%. Differential Scanning calorimetry or X-Ray diffraction can be used to determine the crystallinity of certain polymers. For estimating polymer crystallinity with lower reliability, other techniques such as Small Angle X-ray Scattering and Infrared Spectroscopy are also available. The levels of crystallinity described in the current disclosure correspond to the DSC-measured crystallinity. Particularly, DSC experiments were performed as follows: A small amount of the sample (several milligrams) was heated at a constant heat rate from ambient temperature or sub-ambient to a temperature higher than the Tm for polyester. The heat flow data are collected and plotted against the temperature. The following formula is used to calculate the degree of crystallinity (Xc):

“?Hf” is the enthalpy for melting, which can be calculated by integrating an endothermic melt peak.

“?Hcc” is the enthalpy for cold crystallization. It can be calculated by integrating the exothermic peak of cold crystallization.

“wt the weight fraction polyester in the plastic”

“?Hf.100%” is the melting enthalpy for fully crystalline polymers and can be found in literature.

“As an illustration,?Hf.100% of PET can be taken from literature at 125.5 J/g. (Polymer Data Handbook Second Edition, Edited By James E. Mark. OXFORD 2009). According to literature,?Hf.100% of PLA equals 93 J/g. (Fisher E. W. Sterzel H.J., Wegner G. Investigation of the structure solution grown crystals lactide copolymers using chemical reactions, Kolloid Zeitschrift & Zeitschrift fur Polymere 1973, 251, p 980-990).

“Amorphization” and “amorphization” are used herein. or ?amorphizing? Amorphizing and?amorphizing? are interchangeable terms that refer to a step that decreases the crystallinity of a polymer relative to its crystallinity prior to the amorphizing process. The amorphizing process allows for a decrease in crystallinity by at least 5%. The amorphization step in the invention leads to a polymer in a plastic product that has at least 30%, preferably at maximum 25%, more preferably, at most 20%, and even more preferably, at most 15% crystallinity. The amorphization step is preferred because it reduces the crystallinity by at least 5% or 10%, 20%, 30% and 40%, respectively, as compared to the level of crystallinity prior to the amorphizing process. This results in a polymer that has at most 25%, preferably at maximum 20%, more preferably at maximum 15% crystallinity.

“A ?degrading process? A process where at least one of the polymers in a plastic article is broken down into smaller molecules such as monomers or oligomers and/or carbon dioxide.

“In the context the invention,?”Tg??,?Tc??,?Tccc? and?”Tm???????????????????????????????” respective refer to the glass transition temperature or the crystallization temp and the melting point of a polymer. These temperatures can be calculated using different analytical methods that are well-known to those skilled in the art. Differential scanning calorimetry (DSC), or differential thermal analysis (DTA), may be used to determine the Tg,Tc, Tccc and Tm of polymers. The temperatures of Tg,Tc,Tcc and Tm of the polymers described in this disclosure correspond to those measured using DSC.

“Amorphization Step”

“Inventors have demonstrated that it is possible improve the degradability a plastic product made up of polyesters by subjecting the product to conditions favoring the amorphization of a particular polyester before a depolymerization thereof.” The plastic product can be amorphized to remove at least part of its crystalline structure.

“In one embodiment, the amorphization process involves exposing the plastic product to temperatures at which it is partially or completely molten.”

The invention allows for the use of different polyesters in the plastic product. The plastic product can be advantageously exposed to temperatures at or above Tc or Tm of the target Polyester, i.e. For which depolymerization is planned. Alternativly, the plastic product can be exposed to temperatures at or above Tc or Tm for the polyesters. This may result in the amorphization all polyesters contained within the plastic product.

“In one embodiment, the plastic product also contains thermoplastic polymers other that a polyester. The plastic product can be subjected to temperatures at or above Tc, Tm, or higher than the Tc and Tm of target polyesters, or to temperatures above the highest Tc, Tm, or Tc of thermoplastic polymers in the product.

A skilled person in the art can adjust the temperature of the amorphizing process to suit the target polyester. The plastic product must be heated for a sufficient time to achieve amorphization. Depending on temperature and/or plastic product, this time period could be between 10 seconds to several minutes.

“A preferred embodiment of the amorphization process involves submitting the plastic product to both shear stress and temperature. Preferably, this is at or above Tc of a polyester. To increase amorphization, heating and shear stress should be performed simultaneously.

“In one embodiment, the step for amorphizing may also include cooling the plastic product after heating it. This is to set the plastic product in the amorphized state. The cooling can be done immediately after heating.

“In one embodiment, cooling is achieved by heating the heated plastic product at a temperature below Tg of a polyester.

“In one embodiment, the plastic product is subjected to cooling temperatures subsequently to heating. Preferably, less than 30 seconds. More preferably, less than 20 seconds. Even more preferable, less than 10 seconds.

“Alternatively, you can cool the product by placing it in cold air. Another option is to cool such article with cooling air.

“More generally, any method that can rapidly reduce the temperature of the plastic product could be used.”

“In one embodiment, the process of amorphizing further includes adding at least one degradation agent. Water, monomers and alcohol are all examples of degrading agents. These degrading agents are best added during the heating and/or shear stress phases of the plastic product.

“Preferably, the step that is used to amorphize the plastic product includes at least water addition. Monomers of a polyester are also added to the product during amorphization. Monomers should be selected from monomers in the target polyester (i.e. For which a depolymerization of the monomers is desired. A particular embodiment adds monomers of PET, such as monoethylene glycol and/or Terephthalic Acid and/or Isophthalic Acid, during the step for amorphizing a PET-containing plastic article. These monomers are particularly useful during the heating phase.

“Preferably, these degrading agents should be added at a concentration lower than 20% of the total weight (i.e. “Plastic product and degrading agent) are added at a concentration below 20% of the total mass (i.e., less than 0.05%) before being submitted to the amorphization phase. Another embodiment adds such degrading agents at a concentration of 0.1 to 10%, and more preferably between 0.01 and 5% before the amorphization step.

“In one embodiment, water is added to the heated phase of the plastic article at a concentration greater than 5%, preferable between 10 and 20%. Monomers can also be added to the plastic article’s heating phase at a concentration lower than 10%, preferably below 5% or 4%, and 2%, respectively.

“In one embodiment, the extruder is used to perform the amorphization process. An extruder can be used to simultaneously or sequentially submit a plastic product to both a specific temperature and shear stress. If necessary, the extruder can also be used to add degrading agents. Further, the extruder can cool the plastic product. To achieve the amorphization process, an extruder may be used. This includes single-screw or multi-screw models, dispersive and reciprocating single-screw, co-rotating or counter rotating designs, internal mixers, mini extruders, and mini extruders. An underwater pelletizer that produces mini pellets less than 1 mm is preferred to be attached to the head of an extruder. This will allow for the production of plastic pellets of desired size and replace the step of grinding before depolymerization.

“Amorphization” can also be achieved by any process that allows to break at minimum partially the crystal structure of at least one polyester in the plastic product.

“Alternatively, the step of amorphization can be performed in a reactor or via atomization or solubilization in a solvent or electronic or atomic radiation or cryogenic mechanical atrition (Schexnaydre and al., 2008). Or any other techniques that are known to a person who is skilled in the art.

“Depolymerization Step”

According to the invention, the process of degradation includes, after the amorphizing step is completed, a step depolymerization. Preferably, the depolymerizing steps targets at least one polyester that was targeted by the previous amorphizing step.

“The depolymerizing steps may include a chemical and/or biological depolymerization. Preferably, at least a biologic depolymerization.”

According to a particular embodiment, the process of degrading the invention involves contacting the plastic product using a depolymerase (i.e. an enzyme). The depolymerase should be able to degrade at most one polyester from the plastic product. Preferably, it must also be able to degrade any polyester that has been previously modified by the amorphizing process.

“The depolymerase is advantageously selected from the group consisting of a cutinase, a lipase, a protease, a carboxylesterase, a p-nitrobenzylesterase, an esterase, a scl-PHA depolymerase, a mcl-PHA depolymerase, a PHB depolymerase. A particular embodiment of the invention involves contact with at least two different types depolymerases.

“In a particular embodiment, PET is used as the plastic product. The depolymerase is preferably selected from Thermobifida Cellulosityca or Thermobifida halotolerans. Another embodiment uses a metagenomic database such as LC?Cutinase, described in Sulaiman et. al. (2012) or any functional variant thereof. Another embodiment of the depolymerase includes a lipase that is preferably made from Ideonella sakaiensis. Another embodiment of the depolymerase is a cutinase from Humicola Insolens. Another embodiment uses commercial enzymes like Novozym51032 or any functional variation thereof as the depolymerase.

The enzyme can be either in soluble or solid phase, such as powder. It may also be bound to cell membranes and lipid vesicles or synthetic supports like glass, plastic, polymers or filter membranes. It can be isolated or purified. The invention prefers that the enzymes are expressed, derived from, secreted or isolated from microorganisms. The enzymes can be purified using techniques that are known in the art and stored according to conventional methods. You can modify the enzymes to increase their activity, stability and/or adsorption onto the polymer. The enzymes may contain stabilizing or solubilizing ingredients, such as water and/or glucoserol, sorbitol and dextrin (including maltodextrine/cyclodextrine), starch, propanol, salt, and others.

“Another embodiment involves the contact of the plastic product with a microorganism which expresses and excretes depolymerase. The invention allows the enzyme to be expelled from the culture medium, or toward the cell membrane of the microorganism in which it may be anchored. The microorganism could naturally synthesize depolymerase or it may be a synthetic microorganism that has been modified to insert a recombinant nucleotide sequence, such as a vector, into which the depolymerase is encoded. A vector is an example of a nucleotide molecular encoding depolymerase. plasmids, recombinant viruses, episomes, artificial chromosomes, and the like. The art of transforming the host cell and providing suitable culture conditions for it are well-known to those who are skilled in this field.

“Recombinant microorganisms can be used directly. You can also purify recombinant enzymes from the culture media. Any commonly used separation/purification means, such as salting-out, gel filtration, hydrophobic interaction chromatography, affinity chromatography or ion exchange chromatography may be used for this purpose. Particularly, microorganisms that are capable of synthesizing and excreting depolymerases may be used.

“Accordingly to the invention, multiple microorganisms and/or purified and/or synthetic enzymes can be used simultaneously or sequentially in order to depolymerize different types of polymers contained within a single plastic article or in other plastic articles.”

“The microorganisms of the invention have a modified metabolism to avoid the consumption of monomers and/or the oligomers derived from degraded polymers. The microorganism may be a recombinant microorganism in which the enzymes that degrade monomers and/or Oligomers have been removed or eliminated. Alternately, the invention can be carried out in a medium that contains at least one carbon source so that the microorganism prefers to consume this carbon source over monomers or oligomers.

“Advantageously, the plastic articles are contacted with a culture media containing microorganisms and glucose as a carbon source as well as an existing nitrogen source (e.g. peptone or meat extract, yeast extract or corn steep liquor) or an organic nitrogen source such as ammonium sulfurate or ammonium chloride. The culture medium can also contain inorganic salts, such as sodium ion and potassium ion. The medium can also contain trace components like vitamins and amino acids.

“In one embodiment, depolymerase may be used in conditions that favor its adsorption onto the plastic article. This allows the polymer of a plastic article to more efficiently be depolymerized into monomers and/or other oligomers. A depolymerase that has been modified may have a higher affinity for the polymer of a plastic particle than a wild-type enzyme. The depolymerase can also be used in combination with plastic-binding protein or binding modules to enhance the interaction between it and the polymer of a plastic article.

The time it takes to depolymerize at least one of the polymers of a plastic article can vary depending on the article and the polymer (i.e. the nature and origin of the article, its composition, shape and molecular weight, and so forth). ), the type and amount of microorganisms/enzymes used, as well as various process parameters (i.e., temperature, pH, additional agents, etc.). The temperature must be maintained below an inactivating temperatures. This is the temperature at which depolymerase can no longer be activated and/or the recombinant organism ceases to synthesize depolymerase. In one embodiment, the temperature is kept below the Tg value of the target polyester that will be depolymerized. The pH can be adjusted to improve the efficiency of the process based on several factors such as the target polyester, the solubility and/or development of coproducts. A particular embodiment adjusts the pH to maintain the optimal pH for the depolymerase. A skilled person in the art can easily modify the process parameters for plastic articles and/or polymerases.

“Additional Optional Steps.”

“In one embodiment, the degrading step may include a preliminary polymerizing step that is performed prior to the step of amorphization. It is preferred that the non-depolymerized, polymers from the preliminary depolymerising stage are removed before the step of amorphization.

“In one embodiment, the degrading step may include a pretreatment step to modify mechanically,/or physically,/or chemically,/or biologically, the said pretreatment step being performed prior to the amorphizing and/or depolymerising steps.”

“For example, pretreatment can physically alter the structure of the plastic product to increase contact between the polymers, enzymes, and/or facilitate the amorphization process. Pretreatment can also be used to reduce the microbial charges resulting from wastes.

“In one embodiment, the plastic article can be transformed into an emulsion, or a powder, and then added to a liquid medium that contains the microorganisms/enzymes. The plastic article can also be mechanically ground, granulated or pelleted. By impacting, crushing, grinding or cryogenic grinding to reduce the size of the material and/or modify its shape before it is subject to amorphization. A mechanical pretreatment could also include a sonication or centrifugation, as well as a collisop or a high-pressure homogenizer. It can also include a maceration of liquefaction using a rotary drum or screw press.

“Alternatively, or in addition, you can apply a thermal pretreatment, such as using microwaves. This thermal pretreatment can be used to sterilize, pasteurize or disinfect the plastic product.

“Another embodiment of the plastic product is chemically treated to modify its structure and increase contact between the polymers, enzymes. You can use a basic, acidic or ionic liquid as well as a solvent. You can also use ozonation.

“In some embodiments, the plastic article can also be sorted and washed before it is degraded.

“Several pre-treatments can be combined according to the invention.”

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