Plastic material comprising at least one polymer

Abstract

The invention relates to a plastic material comprising at least one polymer that comprises a plurality of chemical bonds that can be broken by a chemically reversible reaction, the chemical bonds being arranged in the polymer so as to obtain a plurality of oligomers having a molecular weight 5 to 20 times lower than that of the polymer after chemical breakdown of the polymer.

Description

[0001] DESCRIPTION

[0002] Title: Plastic material comprising at least one polymer

[0003] [1] The present invention relates to a plastic material comprising at least one polymer with a plurality of chemical bonds that can be broken by a chemically reversible reaction. The plastic material comprising at least one polymer that can be broken by a chemically reversible reaction allows, in particular, for recycling by chemical and enzymatic means. The invention also relates to a method for recycling this plastic material and a method for recycling a composition comprising this plastic material.

[0004] [2] In many industries, particularly the automotive industry, it is common to use plastic materials whose initial composition may incorporate additives or reinforcing fillers, such as fiberglass. Some official regulations require the use of at least a certain amount of recycled material in the manufacture of plastic materials. Furthermore, using recycled materials can reduce the CO2 footprint in the production of new parts.

[0005] [3] Of course, new parts made with recycled material must have the same qualities as the original parts, in particular they must have adequate mechanical strength and thermal resistance.

[0006] [4] The use of recycled materials after a lifetime of use (also called post-consumer materials or PCM) poses a number of problems. For example, the incorporation of a relatively large quantity of recycled materials can have a negative impact on the properties, particularly mechanical properties, of the final part.

[0007] [5] Chemical recycling processes are also known, for example using pyrolysis. A disadvantage of pyrolysis is the high energy consumption and significant CO2 emissions.

[0008] [6] Another known recycling process is depolymerization, which results in monomers that are incorporated after the steam cracking step as basic chemicals. However, this process consumes solvents and emits chemical substances.

[0009] [7] The present invention aims in particular to improve the recycling of plastic materials.

[0010] [8] The invention thus relates to a plastic material comprising at least one polymer comprising a plurality of chemical bonds which can be broken by a chemically reversible reaction, said chemical bonds being arranged in the polymer so as to obtain a plurality of oligomers having a molecular weight 5 to 20 times lower, preferably 8 to 20 times lower, preferably 10 to 20 times lower compared to that of the polymer after a chemical degradation of said polymer.

[0011] [9] A reversible chemical reaction is a chemical reaction that can proceed in both directions: from reactants to products and from products to reactants. In other words, the products of the reaction can react with each other to reform the original reactants. “Chemical bonds that can be broken by a chemically reversible reaction” thus refers to bonds that can be broken and reformed by the chemically reversible reaction.

[0012]

[0010] Advantageously, the polymer according to the invention allows the thermomechanical properties of the plastic material that has undergone a recycling cycle to be maintained while limiting the supply of new monomers to reform the polymer and the plastic material.

[0013]

[0011] Such a polymer allows the production, after a reversible chemical reaction, of oligomers with a reduced molecular weight compared to the starting polymer (5 to 20 times lower, preferably 8 to 20 times lower, preferably 10 to 20 times lower). These oligomers will then be more easily cleaved by a subsequent reaction, in particular an enzymatic reaction, allowing the production of monomers, for example. However, the chemical bonds that can be broken by a chemically reversible reaction within the polymer are sufficiently spaced to ensure that it retains its mechanical properties.

[0014]

[0012] The term “thermomechanical properties” means, for example, but not limited to, the glass transition temperature, the glass plate modulus, the rubber plate modulus, and the impact resistance of the plastic material.

[0015]

[0013] The term “oligomer” means in particular a chain comprising 2 to 20 repeating units.

[0016]

[0014] According to one aspect of the invention, the polymer belongs to the family of thermosetting polymers and / or thermoplastic polymers and / or vitrimers. Preferably, according to the invention, the polymer belongs to the family of thermoplastic polymers, excluding thermosetting polymers and / or vitrimers.

[0017]

[0015] The term “polymer” means a compound or mixture of compounds whose structure consists of multiple repeating units (formed by one or more monomers, for example, but not limited to these) linked by covalent chemical bonds. In the context of the invention, the term “polymer” includes natural or synthetic polymers. They may consist of a single type of repeating unit (i.e., homopolymers) or a mixture of different repeating units (i.e., copolymers or heteropolymers).

[0018]

[0016] The term “thermosetting polymer” refers to a polymer which, for example, but not limited to, under the action of a temperature increase or by photopriming, gradually hardens to reach an irreversible solid state. A thermosetting polymer is a polymer for which the polymerization reaction, also called the crosslinking reaction, is irreversible and leads to the production of an infusible, insoluble, and non-recyclable plastic material (a plastic material that cannot be reshaped by a temperature increase).

[0019]

[0017] The term “thermoplastic polymer” means a polymer which is malleable under the action of rising temperature, and which can therefore be melted, reshaped and thus recycled.

[0020]

[0018] According to one aspect of the invention, the plastic material comprises at least one polymer selected from:

[0021] - a polyester,

[0022] - a polycarbonate,

[0023] - a polyamine,

[0024] - a polyamide,

[0025] - a polyurethane.

[0026]

[0019] According to one aspect of the invention, the polymer has the following chemical formula:

[0027] [Chem 1] where XX is chosen from CH2-CH2, SS, and est C0m p 0S é q e the family of acetals or ketals)

[0028] YZ is chosen from -NHCO, -OCO, -NHCONH, -NH=CH2 (Y being -O, -NH and Z being -CO, -CONH) and n is an index representing the degree of polymerization, in other words the number of units repeated according to said chemical formula.

[0029]

[0020] According to one aspect of the invention, the chemical bonds that can be broken by a chemically reversible reaction of the polymer are bonds that can be reduced. In other words, the chemical bonds that can be broken by a chemically reversible reaction of the polymer can be broken by a reduction reaction. The chemically reversible reaction is therefore, in this example, a reduction reaction.

[0030]

[0021] In another aspect of the invention, the chemical bonds that can be broken by a chemically reversible reaction of the polymer are hydrolyzable bonds. In other words, the chemical bonds that can be broken by a chemically reversible reaction of the polymer can be broken by hydrolysis. The chemically reversible reaction is therefore, in this example, hydrolysis.

[0031]

[0022] In another aspect of the invention, the chemical bonds that can be broken by a chemically reversible reaction of the polymer are imine bonds. In other words, the chemical bonds that can be broken by a chemically reversible reaction of the polymer can be broken by a transimination reaction. The chemically reversible reaction is therefore, in this example, a transimination reaction.

[0032]

[0023] According to one aspect of the invention, the chemical bonds that can be broken by a chemically reversible reaction of the polymer are urethane (carbamate) bonds. In other words, the chemical bonds that can be broken by a chemically reversible reaction of the polymer can be broken by a transurethanization or transcarbamoylation reaction.

[0033]

[0024] According to one aspect of the invention, the chemical bonds that can be broken by a chemically reversible reaction are chosen from disulfide, acetal, ester, imine, urethane bonds.

[0034]

[0025] According to one aspect of the invention, the polymer has a molecular weight between 50 and 80 kDa for polyamide.

[0035]

[0026] According to one aspect of the invention, said chemical bonds are arranged in the polyamide polymer so as to obtain a plurality of oligomers having a molecular weight between 2 and 14kDa, preferably between 6 and 10kDa, as a result of a chemical degradation of said polyamide polymer.

[0036]

[0027] According to one aspect of the invention, the polymer is obtained by mixing a first functional monomer, in particular an adipic acid or an adipoyl chloride, a second monomer comprising chemical bonds that can be broken by a chemically reversible reaction, in particular a bifunctional diamine-type molecule, preferably a cystamine, and optionally another functional monomer not comprising chemical bonds that can be broken by a chemically reversible reaction, such as a hexamethylenediamine (HDMA).

[0028] According to one aspect of the invention, the polymer has at least 25%, or at least 50%, or at least 75% of chemical bonds that can be broken by a chemically reversible reaction within the polymer.

[0037]

[0029] In particular, the polymer may have 100% chemical bonds that can be broken by a chemically reversible reaction in the polymer.

[0038]

[0030] According to one aspect of the invention, the percentage of chemical bonds that can be broken by a chemically reversible reaction in the polymer corresponds to the mass percentage of the second functional monomer, in particular cystamine, mixed with the first functional monomer, in particular adipic acid or adipoyl chloride, relative to the mass percentage of the other functional monomer not comprising bonds that can be broken by a chemically degradable reaction, in particular hexamethylenediamine, mixed with the first monomer, in particular adipic acid or adipoyl chloride.

[0039]

[0031] In other words, by "the polymer has at least 25% of chemical bonds that can be broken by a chemically reversible reaction in the polymer", we mean a polymer obtained by mixing at least 25% by mass percentage of a molecule such as cystamine, 75% by mass percentage of a molecule such as hexamethylenediamine, with for example adipic acid or adipoyl chloride.

[0040]

[0032] Such a proportion of bonds that can be broken by a chemically reversible reaction in the polymer makes it possible, after a reversible chemical reaction, to obtain oligomers of molecular weight small enough to be easily degraded, for example into monomers during a subsequent degradation reaction (in particular by enzymatic degradation).

[0041]

[0033] Moreover, such percentages of bonds that can be broken by chemically reversible reaction in the polymer allow the thermomechanical properties of the plastic material to be retained.

[0042]

[0034] The present invention also relates to a composition which comprises the plastic material described above, at least one additive, and / or at least one filler.

[0043]

[0035] According to one aspect of the invention, the filler is chosen from glass fiber, natural fiber, talc or mica.

[0044]

[0036] According to one aspect of the invention, the composition comprises between 10% and 60% glass fibers or natural fibers. All percentages are given by weight relative to the total weight of the composition.

[0045]

[0037] According to one aspect of the invention, the composition then comprises between 10% and 40% talc or mica.

[0038] According to one aspect of the invention, at least one additive is chosen from among the following: a stabilizing agent, an antioxidant, a plasticizing agent, a flame retardant, or a mixture of the aforementioned additives.

[0046]

[0039] The plasticizing agent makes it possible to improve the malleability of the composition during its manufacture, for example during a molding step.

[0047]

[0040] According to one aspect of the invention, the composition comprises between 35% and 95% plastic material as described above.

[0048]

[0041] The present invention also relates to a method for recycling a plastic material comprising at least one polymer comprising a plurality of chemical bonds that can be broken by a chemically reversible reaction, said method comprising the following steps:

[0049] 1. Manufacture of said polymer by polymerization of at least two molecules, comprising at least two polymerizable chemical functions, these molecules comprising chemical bonds that can be broken by a chemically reversible reaction,

[0050] 2. Chemical degradation of said polymer by: a. breaking chemical bonds that can be broken by a chemically reversible reaction so as to obtain a plurality of oligomers having a molecular weight 5 to 20 times lower than that of the polymer, b. enzymatic degradation of said oligomers so as to obtain molecules comprising at least two polymerizable chemical functions after reformation of chemical bonds that can be broken by a chemically reversible reaction,

[0051] 3. Obtain the polymer by step 1 from molecules comprising at least two polymerizable chemical functions obtained from step 2.

[0052]

[0042] For example, this aforementioned reformation may be spontaneous or require an action.

[0053]

[0043] In one aspect of the invention, at least one of the molecules comprising at least two polymerizable chemical functions comprises a functional monomer, or a functional oligomer, or a functional prepolymer or a combination of prepolymers comprising one or more chemical bonds that can be broken by a chemically reversible reaction.

[0054]

[0044] In one aspect of the invention, where each molecule comprises a functional monomer, these functional monomers are identical from one molecule to another. Alternatively, the functional monomers are different from one molecule to another.

[0055]

[0045] According to one aspect of the invention, the manufacture of the polymer is carried out by polycondensation polymerization or by addition polymerization of at least two molecules each comprising at least one functional monomer.

[0056]

[0046] According to one aspect of the invention, the polymer manufacturing step is carried out by interfacial polycondensation polymerization.

[0057]

[0047] Preferably, the interfacial polycondensation polymerization is carried out at a temperature of at least 20°C, and preferably between 20°C and 60°C.

[0058]

[0048] According to one aspect of the invention, the reformation of chemical bonds that can be broken by a chemically reversible reaction takes place simultaneously with enzymatic degradation.

[0059]

[0049] According to one aspect of the invention, the reformation of chemical bonds that can be broken by a chemically reversible reaction is achieved by an oxidation reaction.

[0060]

[0050] According to one aspect of the invention, the reformation of chemical bonds that can be broken by a chemically reversible reaction is achieved by a condensation reaction, particularly for acetal or ester polymers for example.

[0061]

[0051] According to one aspect of the invention, the step of breaking chemical bonds that can be broken by a chemically reversible reaction makes it possible to obtain oligomers of the following formula:

[0062] [Chem 2] where X is chosen from -CH2, -S, -O,

[0063] YZ is chosen from -NHCO, -OCO, -NHCONH, -NHCH2 (Y being -O, -NH and Z being -CO, -CONH) and m is an index representing the degree of polymerization, in other words, the number of repeated units.

[0052] According to one aspect of the invention, the step of chemically breaking the chemical bonds that can be broken by a chemically reversible reaction is chosen from a chemical reduction reaction, a hydrolysis reduction, or a transimination reaction.

[0064]

[0053] For example, when the chemical bond that can be broken by a chemically reversible reaction is a bond that can be reduced, in particular a disulfide bond, the breaking step is a reduction reaction such as a disulfide metathesis reaction.

[0065]

[0054] For example, the polyamides obtained after the manufacturing step have disulfide bonds which can be broken initially, thus allowing the production of oligomers with smaller molecular weights, the recovery of solubility in solvents compatible with enzymes and the reduction of crystallinity compared to the starting polyamide.

[0066]

[0055] The products obtained after this first breaking step are then subjected to enzymatic degradation. This allows the functional monomers to be recovered for recycling and reforming the initial polyamide.

[0067]

[0056] It is worth noting the semi-crystalline nature and the numerous hydrogen bonds between the amide groups in polyamides, which give them high solvent stability. However, these characteristics also make these polymers poorly soluble, and they can only be solubilized in very specific solvents, for example, fluorinated solvents and / or acids.

[0068]

[0057] In one aspect according to the invention, the reduction is carried out by a reducing agent selected from mercaptoethanol, glutathione, dithiothreitol, dithioerythritol, dithiobutylamine.

[0069]

[0058] In another example, when the chemical bond that can be broken by a chemically reversible reaction is a hydrolyzable bond, the chemical reaction is a hydrolysis, in particular an acid hydrolysis for a hydrolyzable bond such as an acetal bond or a basic hydrolysis for a hydrolyzable bond such as an ester bond.

[0070]

[0059] In another example, when the chemical bond that can be broken by a chemically reversible reaction is an imine bond, the breaking step is a transimination.

[0071]

[0060] According to one aspect of the invention, the reformation of chemical bonds that can be broken by a chemically reversible reaction makes it possible to obtain the functional monomers used in the polymer manufacturing step, said functional monomers having the following formulas: [Chem 3] where XX is chosen from CH2-CH2, SS and

[0072] Y is chosen from -O, -NH and Z is chosen from -CO, -CONH

[0073]

[0061] According to one aspect of the invention, the enzymatic degradation step of the oligomers is carried out by means of at least one hydrolysis enzyme.

[0074]

[0062] According to one aspect of the invention, the hydrolysis enzyme may be of the polyamidase, cutinase, or esterase type.

[0075]

[0063] According to one aspect of the invention, the step of breaking chemical bonds that can be broken by a chemically reversible reaction is carried out with a yield of between 90% and 100%, preferably a yield of 100%.

[0076]

[0064] Advantageously, the plastic material recycling process allows for the recovery of the polymer it comprises, with a high yield of between 80% and 100%.

[0077]

[0065] According to one aspect of the invention, the enzymatic degradation step of the oligomers is carried out at a temperature above 25°C.

[0078]

[0066] According to one aspect of the invention, the plastic material recycling process includes the following steps carried out prior to the polymer manufacturing step: solubilization of at least one first functional monomer, in an organic phase, solubilization of at least one second functional monomer, in an alkaline aqueous phase.

[0079]

[0067] Alternatively, the solubilization step of the first functional monomer can be carried out in an alkaline aqueous phase, and the solubilization of the second functional monomer can be carried out in an organic phase.

[0080]

[0068] The term “alkaline aqueous phase” means a medium comprising one or more basic substances solubilized in water.

[0081]

[0069] The term “organic phase” should be understood as a medium comprising at least one organic solvent or a mixture of several organic solvents.

[0070] In one aspect of the invention, the organic solvent is chosen from among water-immiscible solvents that solubilize the functional monomers, particularly from among dichloromethane, THF, 2me-THF, diethyl ether, hexane, heptane, pentane, chloroform, cyclohexane, toluene, and benzene.

[0082]

[0071] According to one aspect of the invention, the first functional monomer can be a bifunctional molecule of the diacid type, such as dichloride acids and dicarboxylic acids. Preferably, the first functional monomer is selected from terephthaloyl chloride, sebacoyl chloride, adipoyl chloride, and adipic acid.

[0083]

[0072] In one aspect of the invention, the first functional monomer comprises a chemical bond that can be broken by a chemically reversible reaction.

[0084]

[0073] Alternatively, the first functional monomer or the second functional monomer does not include chemical bonds that can be broken by a chemically reversible reaction.

[0085]

[0074] According to one aspect of the invention, the second functional monomer is a bifunctional molecule of the diamine type and comprising chemical bonds that can be broken by a chemically reversible reaction of the disulfide type, such as cystamine, or other derived salts.

[0086]

[0075] Alternatively, the second functional monomer is a bifunctional diol-type molecule comprising chemical bonds that can be broken by a chemically reversible disulfide-type reaction. Preferably, the second functional monomer is selected from a 2-hydroxyethyl disulfide or dithio dipropionic acid.

[0087]

[0076] Alternatively, the second functional monomer comprises chemical bonds that can be broken by a chemically reversible reaction of the acetal and / or derived salt type. For example, this could be the commercial molecules Recyclamine® R101, R301.

[0088]

[0077] As a further alternative, the first and second functional monomers may be bifunctional molecules of different structure and comprising the same chemical bonds which can be broken by a chemically reversible reaction. For example, the first functional monomer and the second functional monomer may each comprise diamines or diacids.

[0089]

[0078] Under this alternative, the first and second functional monomers can be solubilized in the same phase. In particular, the first functional monomer and the second functional monomer can be solubilized in two organic phases.

[0090]

[0079] Thus, each of the functional monomers can be solubilized in two different and immiscible organic solvents.

[0080] For example, the two organic phases can be organic solvents, preferably volatile, chosen from the following: an ether or its derivatives such as diethyl ether; a light hydrocarbon or a mixture of light hydrocarbons such as hexane; a light chlorinated hydrocarbon such as chloroform or methylene chloride;

[0091] - any other common solvents such as acetonitrile, dioxane, tetrahydrofuran, 2-methyltetrahydrofuran and mixtures thereof.

[0092]

[0081] According to one aspect of the invention, the process comprises a step of mixing a first functional monomer, in particular adipic acid or adipoyl chloride, a second monomer comprising chemical bonds that can be broken by a chemically reversible reaction, in particular a bifunctional diamine-type molecule, preferably cystamine, and optionally another functional monomer not comprising chemical bonds that can be broken by a chemically reversible reaction, such as hexamethylenediamine (HDMA), so as to obtain a polymer comprising bonds that can be broken by a chemically reversible reaction

[0093]

[0082] The present invention relates to a plastic material comprising at least one polymer comprising a plurality of chemical bonds that can be broken by a chemically reversible reaction, said plastic material being capable of being obtained by the recycling process described above.

[0094]

[0083] In one aspect of the invention, the plastic material is capable of being obtained by mixing a first functional monomer, in particular an adipic acid or an adipoyl chloride, a second monomer comprising chemical bonds that can be broken by a chemically reversible reaction, in particular a bifunctional molecule of the diamine type, preferably a cystamine, and optionally another functional monomer not comprising chemical bonds that can be broken by a chemically reversible reaction, such as a hexamethylenediamine (HDMA).

[0095]

[0084] The present invention also relates to a method for recycling a composition such as that described above according to the following steps,

[0096] 1. Manufacture of the composition by mixing plastic material based on at least one polymer comprising a plurality of chemical bonds that can be broken by a chemically reversible reaction with at least one additive and / or at least one filler, in particular glass fiber,

[0097] 2. For the purpose of recycling, separation of the filler, additives and plastic material, in particular by chemical recycling and solid / liquid separation processes, so as to obtain at least the recycled filler and the plastic material,

[0098] 3. Recycling of the plastic material according to the process described above to obtain recycled plastic material,

[0099] 4. Mixing of recycled plastic material, recycled filler and additives to obtain the composition of step 1.

[0100]

[0085] Advantageously, the composition recycling process is carried out at a temperature of no more than 180°C, which allows the fillers to be reused in a new manufacturing step of the composition.

[0101]

[0086] According to one aspect of the invention, the step of separating the filler from the plastic material is carried out by filtration.

[0102]

[0087] The invention also relates to the use of the composition as described above, to manufacture parts by injection molding.

[0103]

[0088] In one aspect of the invention, the composition is adapted for manufacturing parts for a motor vehicle, in particular for a motor vehicle heat exchanger, or a ventilation system, a front module, a battery box, or an AC unit, for example. Applications in other fields (other than automotive) are of course conceivable.

[0104]

[0089] The present invention thus makes it possible, through the reuse of a high proportion (in particular close to 100%) of end-of-life recycled materials, to comply with official regulations. The invention therefore enables a virtuous and sustainable manufacturing and recycling cycle for plastic materials, unlike conventional recycling processes. The present invention makes it possible to reuse post-consumer plastic materials, through depolymerization, in a closed loop, and with a material potentially reusable "indefinitely," without loss of properties (mechanical, thermal, and chemical).

[0105]

[0090] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0106]

[0091] [Fig. 1] Figure 1 is a schematic view of the recycling process of a composition according to the invention;

[0107]

[0092] [Fig. 2] Figure 2 schematically illustrates the chemical reactions of the polyamide 6.6 polymer recycling process according to the invention.

[0093] Figure 1 shows a recycling process 100 of a composition 1. Composition 1 comprises, on the one hand, a plastic material 5 based on a polyamide polymer 2 and, on the other hand, a filler 6 and an additive 7.

[0108]

[0094] The polyamide 2 polymer has a molecular weight between 50 kDa and 80 kDa and comprises a plurality of disulfide bonds 3, these chemical bonds being able to be broken by a chemically reversible reaction which is here a reduction reaction.

[0109]

[0095] The filler 6 is, for example, glass fiber or natural fiber.

[0110]

[0096] Additive 7 is for example a stabilizing agent, an antioxidant, a plasticizing agent, a flame retardant or a mixture of these.

[0111]

[0097] The recycling process 100 is carried out according to the following steps:

[0112] 1. manufacturing (step 10) of composition 1 by mixing the plastic material 5 according to the invention, the filler 6 and the additive 7,

[0113] 2. Separation (step 20) of the filler 6, the additive 7, and the plastic material 5 by chemical recycling and solid / liquid separation processes. Thus, at the end of separation step 20, the filler 6 is isolated from composition 1 so that it becomes recycled filler 60. The plastic material 5 is also isolated at the end of separation step 20.

[0114] 3. Recycling (step 30) of the plastic material 5 to obtain recycled plastic material 50, according to the following steps: a. Breaking (step 31) of the disulfide bonds 3 by reduction of the polyamide polymer 2 so as to obtain a plurality of oligomers 8 having a lower molecular weight between 2 kDa and 14 kDa, b. Enzymatic degradation (step 32) of said oligomers

[0115] 8 in order to obtain functional monomers 9 after reformation of disulfide bonds by oxidation, c. polymerization (step 33) of the functional monomers

[0116] 9 to obtain the polyamide 2 polymer which forms the recycled plastic material 50,

[0117] 4. Mixing (step 40) of recycled plastic material 50, recycled filler 60 and a new additive 7 to obtain the composition of step 1.

[0118]

[0098] Example 1

[0119] Polyamide 6.6 (polyhexamethylene adipamide) contains disulfide bonds. Polyamide 6.6 (PA 6.6) is obtained by an interfacial polycondensation polymerization reaction between a first adipoyl chloride monomer (10g) without disulfide bonds solubilized in an organic phase which is dichloromethane (265 ml), and a second diamine monomer containing disulfide bonds which is cystamine (8.735 g) or cystamine salts in an alkaline aqueous solution (133 ml) of sodium hydroxide which has a molar concentration of 1 mol / L.

[0120]

[0099] Initially, the two phases are prepared separately in beakers under magnetic stirring so as to solubilize the monomers in their respective solutions.

[0121]

[0100] The organic phase (adipoyl chloride) is introduced into a three-necked, round-bottom flask, which is placed under mechanical stirring. The aqueous phase (cystamine or cystamine salts) is placed in a dropping funnel. Under mechanical stirring, the aqueous phase is added dropwise to the organic phase. The polycondensation reaction (RT / 1 atm) allows the polyamide 6.6 polymer to rapidly form by precipitation in the medium as a white, flaky / powdery solid, depending on the cystamine fraction. The reaction is allowed to proceed for two hours under stirring.

[0122]

[0101] After two hours of reaction, stirring is stopped and the solid polyamide 6.6 is recovered by filtration (Buchner + sintered). After a quick rinse with dichloromethane, the solid is washed three times with acetone to remove traces of water. Then, two final rinses with pentane are performed to remove all traces of other solvents. The residual product is finally dried under vacuum at 90 °C for two to three hours.

[0123]

[0102] The molecular weight of the polymer is calculated, for example, by gel permeation chromatography (GPC, for Gel Permeation Chromatography) which is carried out in an HFIP (hexafluoroisopropanol) solvent.

[0124]

[0103] [Table]

[0125] 'adipoyl chloride without disulfide bonds ** cystamine

[0126]

[0104] Example 1a The polyamide 6.6 of Example 1 undergoes a degradation and reformation step according to the recycling cycle of the invention. For this purpose, the disulfide bonds of the polyamide 6.6 are broken by disulfide metathesis with a reducing agent contained in a solvent A and a catalyst to accelerate the chemical degradation of the disulfide bonds. Once the disulfide bonds have been broken, the residual product is washed and filtered in a solvent B to obtain a filtrate containing the oligomers.

[0127]

[0105] Polyamide 6.6 is exposed to a solution containing 5 to 20% reducing agent in solvent A at a temperature between room temperature and 100°C for 24 to 72 hours.

[0128]

[0106] The reducing agent may be chosen from mercaptoethanol, glutathione, dithiothreitol, dithioerythritol, or dithiobutylamine. In this example 1a, the reducing agent is mercaptoethanol.

[0129]

[0107] Solvent A can be chosen from dimethylformamide (DMF), 2-methyltetrahydrofuran (ME-THF), gamma-valerolactone, or methoxycyclopentane (CPME). In this example 1a, solvent A is DMF, or dimethylformamide.

[0130]

[0108] A catalyst is added to accelerate the degradation. The catalyst can be chosen from the family of tertiary phosphines such as tris-(hydroxymethyl)phosphine, tris(carboxyethyl)phosphine, tris(3-hydroxypropyl)phosphine or tertiary amines such as 4-dimethylaminopyridine (DMAP), 1,4-diazabicyclo[2.2.2]octane (DABCO) or N,N-dimethylaniline.

[0131]

[0109] After the disulfide bonds have broken, the solid residue is filtered (15–30 mbar / 20–40°C) and washed with solvent B. The residue is then dried (1 atm / RT) to obtain oligomers. Solvent B can be chosen from dichloromethane, acetone, or n-pentane. In this example 1a, solvent B is dichloromethane.

[0132]

[0110] The molar concentration of the oligomers obtained is characterized using gel permeation chromatography (GPC).

[0133]

[0111] The oligomers are then enzymatically degraded by a polyamidase-type hydrolytic enzyme. At the same time and simultaneously, the reformation of disulfide bonds is carried out by an oxidation reaction (by contact with atmospheric oxygen) so as to reform the functional monomers used in the interfacial polycondensation polymerization of polyamide 6.6 (see process in Example 1).

[0134]

[0112] The oligomers obtained have a molecular weight between 2 and 14 kDa.

[0135]

[0113] Polyamide 6.6 of formula 1, oligomers of formula 2 and functional monomers of formula 3 are visible in Figure 2.

[0136]

[0114] Example 2

[0115] In the second example, conditions similar to those in Example 1 apply. In this example, the process includes a step of mixing adipoyl chloride, cystamine, and hexamethylenediamine (HDMA) to obtain a polymer comprising bonds that can be broken by a chemically reversible reaction.

[0137]

[0116] For example, 75% cystamine and 25% HDMA can be mixed with adipoyl chloride. In this way, by using 75% cystamine and 25% HDMA, the polymer obtained after polymerization will contain 75% disulfide bonds that can be reduced in a reduction reaction. Thus, during the chemical degradation step of the polymer (reduction reaction), lower molecular weight oligomers are obtained. Enzymatic degradation then reduces these oligomers to monomers, which are then mixed together again to obtain the starting polymer containing a plurality of chemically reversible bonds.

Claims

DEMANDS

1. Plastic material comprising at least one polymer comprising a plurality of chemical bonds which can be broken by a chemically reversible reaction, said chemical bonds being arranged in the polymer so as to obtain a plurality of oligomers having a molecular weight 5 to 20 times lower than that of the polymer after chemical degradation of said polymer.

2. Plastic material according to claim 1 comprising at least one polymer selected from: - a polyester, - a polycarbonate, - a polyamine, - a polyamide, - a polyurethane.

3. Plastic material according to any one of the preceding claims, wherein the chemical bonds that can be broken by a chemically reversible reaction are selected from disulfide, acetal, ester, imine, urethane bonds.

4. A method for recycling a plastic material according to any one of the preceding claims, comprising at least one polymer comprising a plurality of chemical bonds that can be broken by a chemically reversible reaction, said method comprising the following steps:

1. Manufacture of said polymer by polymerization of at least two molecules, comprising at least two polymerizable chemical functions, these molecules comprising chemical bonds that can be broken by a chemically reversible reaction, 2. Chemical degradation of said polymer by: a. breaking chemical bonds that can be broken by a chemically reversible reaction so as to obtain a plurality of oligomers having a molecular weight 5 to 20 times lower than that of the polymer, b. enzymatic degradation of said oligomers so as to obtain molecules comprising at least two polymerizable chemical functions after reformation of chemical bonds that can be broken by a chemically reversible reaction, 3. Obtain the polymer by step 1 from molecules comprising at least two polymerizable chemical functions obtained from step 2.

5. A process according to claim 4, wherein the manufacturing step is carried out with at least one of the molecules comprising at least two polymerizable chemical functions includes a functional monomer, or a functional oligomer, or a functional prepolymer or a combination of prepolymers comprising one or more chemical bonds that can be broken by a chemically reversible reaction.

6. A process according to claim 4, wherein the polymer manufacturing step is carried out by interfacial polycondensation polymerization.

7. A method according to claim 4, wherein the enzymatic degradation step of the oligomers is carried out by means of at least one hydrolysis enzyme.

8. Composition comprising the plastic material according to any one of claims 1 to 3, at least one additive, and at least one filler.

9. Composition according to claim 8, adapted for manufacturing parts for a motor vehicle, in particular for a motor vehicle heat exchanger, or a ventilation system, a front module, a battery box, or an HVAC box for example.

10. A method for recycling a composition according to claim 8 or 9, according to the following steps:

1. Manufacture of the composition by mixing plastic material based on at least one polymer comprising a plurality of chemical bonds that can be broken by a chemically reversible reaction with at least one additive and / or at least one filler, in particular glass fiber, 2. For the purpose of recycling, separation of the filler, additives and plastic material, by chemical recycling and solid / liquid separation processes, so as to obtain at least the recycled filler and the plastic material, 3. Recycling of plastic material according to the process according to any one of claims 4 to 7 to obtain recycled plastic material, 4. Mixing of recycled plastic material, recycled filler and additives to obtain the composition of step 1.

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