Process for recycling material comprising polyethylene terephthalate

Abstract

The present invention relates to a method for recycling a material comprising polyethylene terephthalate (PET), comprising: a) a step of treating the material, optionally previously ground, with at least one glycol comprising from 2 to 10 carbon atoms to obtain at least one polyol; b) a step of treating the at least one polyol obtained with at least one dicarboxylic acid comprising from 2 to 21 carbon atoms in order to reduce the hydroxyl number of the at least one polyol.

Description

Title of the invention: Method for recycling material comprising polyethylene terephthalate Field of invention

[0001] The present invention relates to a method for recycling material, in particular fabric, comprising polyethylene terephthalate (PET) to prepare polyols. The present invention also relates to the use of the recycled polyols for the manufacture of materials such as insulators, elastomers, coatings and adhesives. Technical background

[0002] Polyols are essential intermediate components used in the composition of various materials such as foams, elastomers, coatings and contributing in particular to their properties of adhesion, flexibility and chemical and mechanical resistance.

[0003] Traditional methods of manufacturing polyols involve the use of raw materials from petrochemical sources which are neither renewable nor biodegradable and therefore contribute to environmental problems related in particular to resource depletion and greenhouse gas emissions.

[0004] In the face of growing environmental challenges and the need to adopt more sustainable industrial practices, the development and production of polyols derived from natural sources and / or recyclable materials is of great interest.

[0005] Polyethylene terephthalate (PET) is a thermoplastic polyester used primarily for the manufacture of food packaging. The high popularity of PET and its non-biodegradability generate enormous amounts of waste. There is therefore a growing demand for the development of PET recycling technologies.

[0006] However, food packaging, such as disposable beverage bottles, is often made from a complex mixture of plastics, making it difficult to chemically recycle it. The majority of polyethylene terephthalate waste is therefore mechanically recycled and reused to produce new food packaging.

[0007] It is therefore necessary to identify new sources of materials comprising PET that can be recycled efficiently. It is also necessary to develop a process for recycling materials comprising PET to produce specific polyols, thus making it possible to offer an ecological alternative to petroleum-based polyols. To be attractive, it is also essential that polyols derived from recycled materials and products obtained from these polyols offer performance at least equal to that of traditional petrochemical products and at comparable prices. Summary of the invention

[0008] The present invention arises from the unexpected discovery by the inventors that fabrics comprising polyethylene terephthalate (PET) can be chemically recycled by a 2-step synthesis, glycolysis followed by esterification, to give polyols. The inventors have demonstrated that these polyols can be used in the manufacture of polyurethane foams and that the foams obtained have characteristics comparable to foams obtained from petroleum-sourced polyols.

[0009] Thus, the present invention relates to a method for recycling a material comprising polyethylene terephthalate (PET), comprising:

[0010] a) a step of treating the material, optionally previously ground, with at least one glycol comprising from 2 to 10 carbon atoms to obtain at least one polyol;

[0011] b) a step of treating at least one polyol obtained with at least one dicarboxylic acid comprising from 2 to 21 carbon atoms in order to reduce the hydroxyl number of the at least one polyol.

[0012] The present invention also relates to a polyol obtained or capable of being obtained by a process for recycling a material comprising polyethylene terephthalate (PET) as defined above.

[0013] The present invention also relates to the use of a polyol obtained or capable of being obtained by a process for recycling a material comprising polyethylene terephthalate (PET) as defined above, for the preparation of a polyurethane foam, polyisocyanurate foam, an elastomer, a coating or an adhesive.

[0014] The present invention also relates to a polyurethane polymer manufactured from a polyol obtained or capable of being obtained by a process for recycling a material comprising polyethylene terephthalate (PET) as defined above.

[0015] The present invention also relates to a polyisocyanurate polymer manufactured from a polyol obtained or capable of being obtained by a process for recycling a material comprising polyethylene terephthalate (PET) as defined above.

[0016] The present invention also relates to a composition comprising at least one polyol obtained or capable of being obtained by a process for recycling a material comprising polyethylene terephthalate (PET) as defined above and capable of forming a foam, an elastomer, a coating, or an adhesive.

[0017] The present invention also relates to a foam, an elastomer, a coating, or an adhesive prepared from at least one polyol obtained or capable of being obtained by a process for recycling a material comprising polyethylene terephthalate (PET) as defined above.

[0018] The present invention also relates to a process for preparing polyurethane or polyisocyanurate foam comprising: - a step of supplying a material comprising PET; - a step a) of processing the material, possibly previously crushed, with at least one glycol comprising from 2 to 10 carbon atoms to obtain at least one polyol; - a step b) of treating at least one polyol obtained with at least one dicarboxylic acid comprising from 2 to 21 carbon atoms in order to reduce the hydroxyl number of the at least one polyol; - a step of mixing at least one polyol in a polyurethane or polyisocyanurate foam formulation. Detailed description of the invention

[0019] As used herein, the term "comprising" is synonymous with "including", "containing" or "encompassing", i.e., when an object "comprises" one or more characteristics, other characteristics than those mentioned may also be included in the object. Conversely, the expression "consisting of" means "made up of", i.e., when an object "consists of" one or more characteristics, the object cannot include other characteristics than those mentioned.

[0020] Material

[0021] Polyethylene terephthalate (PET), well known to those skilled in the art, is an amorphous semi-crystalline thermoplastic belonging to the polyester family. PET has the following formula (I):

[0022] [Chem.l]

[0023] (I)

[0024] in which n represents the number of diester units in the PET.

[0025] PET is produced from raw materials such as terephthalic acid and ethylene glycol. PET is a polyester that can be synthesized by two different methods. The first method involves a direct reaction of a terephthalic acid with an ethylene glycol to produce PET. This reaction is an ester Fisher synthesis in which a carboxylic acid reacts with an alcohol to generate water. The equilibrium is shifted towards ester formation by removing the generated water from the reaction medium. The other synthesis to produce PET involves a transesterification reaction in which one ester is converted into another by reacting dimethyl terephthalate with ethylene glycol to generate methanol.

[0026] Preferably, the material according to the invention comprises at least 50% (m / m) of PET relative to the total mass of the material, for example at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% (m / m) of PET relative to the total mass of the material. Preferably, the material according to the invention comprises from 50% to 95% (m / m) of PET, for example from 50% to 90%, from 50% to 85%, from 50% to 80%, from 50% to 75%, from 50% to 70%, from 50% to 65%, from 50% to 60%, from 60% to 95%, from 60% to 90%, from 60% to 85%, from 60% to 80%, from 60% to 75%, from 60% to 70%, from 60% to 65%, from 70% to 95%, from 70% to 90%, from 70% to 85%, from 70% to 80%, from 70% to 75%, 80% to 95%, 80% to 90%, and 80% to 85% (m / m) of PET relative to the total mass of the material.

[0027] The PET in the material may be recycled PET (rPET), i.e., PET from the recycling of PET waste such as food packaging. According to one embodiment of the invention, the material may comprise at least 1% (m / m) of recycled PET relative to the total mass of PET in the material. Thus, at least 1%, at least 2%, at least 5%, at least 6%, at least 7%, at least 8%, at least 10%, at least 12%, at least 15%, at least 18%, at least 20%, at least 22%, at least 25% (m / m) of the PET present in the material is recycled PET.

[0028] Elastane, also known as Spandex or Lycra, is a type of poly(urethane-urea) well known to those skilled in the art, generally made from a prepolymer, a diisocyanate (usually MDI) and a long diol such as poly(propylene glycol) (PPG) or polytetrahydrofuran (PTMEG). This prepolymer subsequently reacts with a short diamine, usually ethylenediamine or pro-pylenediamine. This results in the formation of urea bonds and rigid segments in the polymer structure. Finally, stabilizers are added such as magnesium stearate or other polymers such as poly(dimethyl-siloxane) to prevent the fibers from sticking together.

[0029] Preferably, the material according to the invention comprises from 1% to 50% (m / m) of elastane relative to the total mass of the material, for example from 5% to 50%, from 5% to 45%, from 5% to 40%, from 5% to 35%, from 5% to 30%, from 5% to 25%, from 5% to 20%, from 5% to 15%, from 5% to 10%, from 8% to 30%, from 8% to 25%, from 8% to 20%, from 8% to 15%, from 8% to 10%, from 10% to 50%, from 10% to 45%, from 10% to 40%, from 10% to 35%, from 10% to 30%, 10% to 25%, 10% to 20%, 10% to 15%, 20% to 50%, 20% to 45%, 20% to 40%, 20% to 35%, 20% to 30%, 20% to 25%, 30% to 50%, 30% to 45%, from 30% to 40%, and from 30% to 35% (m / m) of elastane. Preferably, the material according to the invention comprises at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40% (m / m) and less than 50% (m / m) of elastane relative to the total mass of the material. Preferably, the material according to the invention comprises less than 50%, less than 45%, less than 40%, less than 35%, less than 30%, less than 35%, less than 25%, less than 20%, less than 15%, less than 10%, less than 5%, (m / m) and more than 1% (m / m) of elastane relative to the total mass of the material.

[0030] The material according to the invention may further comprise a flame retardant. Examples of flame retardants that may be mentioned are bromine compounds such as tetrabromobisphenol A (TBBPA) and polybromodiphenyl ether (PBDE); phosphorus compounds such as triphenylphosphine (TPP) and phosphoric esters such as triethyl phosphate and tris(2-chloropropyl)phosphate; nitrogen compounds; silicone compounds such as brominated silicones; and aluminum compounds such as aluminum hydroxide and aluminum trihydrate.

[0031] Preferably, the material according to the invention comprises from 1% to 20% (m / m) of a flame retardant relative to the total mass of the material, for example from 1% to 15%, from 1% to 10%, from 1% to 8%, from 1% to 5%, from 2% to 20%, from 2% to 18%, from 2% to 15%, from 2% to 12%, from 2% to 10%, from 2% to 8%, from 2% to 5%, from 5% to 20%, from 5% to 15%, from 5% to 12%, from 5% to 10%, and from 5% to 8% (m / m) of a flame retardant.

[0032] The material may also comprise a coating. The coating may be chosen from any type of coating well known to those skilled in the art and compatible with a material comprising PET. Examples of coatings include acrylic, polyurethane, epoxy, polyethylene, polyvinyl chloride, polyvinylidene chloride, silicone, fluoropolymer such as polytetrafluoroethylene, ethylene tetrafluoroethylene, fluorinated ethylene propylene, wax, latex, nylon and mixtures thereof.

[0033] Preferably, the material according to the invention comprises 1% to 40% (m / m) of a coating, for example 1% to 10%, 1% to 15%, 1% to 20%, 1% to 25%, 1% to 30%, 5% to 10%, 5% to 15%, 5% to 20%, 5% to 25%, 5% to 30%, 5% to 35%, 10% to 15%, 10% to 20%, 10% to 25%, 10% to 30%, 10% to 35%, 10% to 40%, 15% to 20%, 15% to 30%, 15% to 35%, 15% to 40%, 20% to 25%, 20% to 30%, 20% to 35%, 20% to 40%, 30% to 35%, 30% to 35% (m / m) of a coating.

[0034] The material according to the invention may also comprise at least one additive such as, for example, a bleaching agent, a fabric softener, an antistatic agent, an anti-UV agent, an antimicrobial agent, a water-repellent agent, a dyeing agent, a controlled shrinkage agent and mixtures thereof.

[0035] Preferably, the material according to the invention comprises from 0.1% to 5% (m / m) of an additive relative to the total mass of the material, for example from 0.2% to 5%, from 0.2% to 3%, from 0.2% to 1%, from 0.5% to 5%, from 0.5% to 4%, from 0.5% to 3%, from 0.5% to 2.5%, from 0.5% to 2%, from 0.5% to 1.5%, from 0.5% to 1%, from 1% to 3%, from 1% to 2.5%, from 1% to 2%, and from 1% to 1.5% (m / m) of an additive.

[0036] Preferably, the material according to the invention is a fabric. As used herein, the terms "fabric" and "textile" may be used interchangeably and include fibers, filaments, yarns as well as woven and non-woven fabrics, knitted fabrics and finished products such as clothing, canvas, tents, wall hangings, bags, etc.

[0037] Preferably, the fabric according to the invention is a fabric intended for event, decorative or commercial purposes. Thus, the fabric according to the invention is preferably selected from the group consisting of fabrics for decoration, furnishing, and covering points of sale, stands, performance halls or spaces, particularly during events such as trade fairs, trade shows, shows or exhibitions.

[0038] Preferably, the fabric according to the invention is selected from the group consisting of finished products as well as scraps and waste generated during the manufacture of the fabric, during its cutting, during its printing, during its transport, or during its installation.

[0039] The fabric according to the invention can be chosen from any fabric intended for event, decorative or commercial purposes well known to those skilled in the art such as, for example, table covers, counter covers, fabrics for covering background panels, fabrics for covering partitions, fabrics for covering exhibition walls, floor coverings, banners, streamers, flags, tablecloths, and fabric display panels.

[0040] The fabric according to the invention may have one or more characteristics making it suitable for use for event, decorative or commercial purposes such as lightness, elasticity, ease of printing, wrinkle resistance, resistance to fading, ease of maintenance, scratch resistance, and flame resistance.

[0041] The fabric according to the invention may comprise a mixture of fabrics. For example, the fabric according to the invention may comprise at least 2 fabrics, at least 3 fabrics, at least 4 fabrics, at least 5 fabrics, at least 6 fabrics, at least 7 fabrics, at least 8 fabrics, at least 9 fabrics, at least 10 different fabrics. Each of the fabrics in the mixture may have a different origin and a different composition.

[0042] Typically, the fabrics in the fabric blend may have different amounts of PET. Some, but not necessarily all, fabrics in the blend may include elastane, at least one retardant flame and / or at least one additive.

[0043] For example, the fabric may comprise at least 1 fabric comprising elastane and at least one fabric not comprising elastane.

[0044] The fabric may comprise at least one fabric comprising between 50% and 70% (m / m) of PET relative to the total mass of the material and at least one fabric comprising more than 70% (m / m) of PET relative to the total mass of the material.

[0045] The fabric may comprise at least one fabric comprising a coating, and at least one fabric not comprising a coating.

[0046] The thickness of the fabric according to the invention can vary from a few millimeters to a few centimeters, for example from 0.1 mm to 5 cm, from 0.1 mm to 4 cm, from 0.1 mm to 3.5 cm, from 0.1 mm to 3 cm, from 0.1 mm to 2.5 cm, from 0.1 mm to 2 cm, from 0.1 mm to 1.5 cm, and from 0.1 to 1 cm.

[0047] The weight of the fabric according to the invention is preferably between 100 and 400 g / m2, preferably between 150 g / m2 and 300 g / m2, for example between 180 g / m2 and 290 g / m2, between 190 g / m2 and 280 g / m2, between 200 g / m2 and 280 g / m2, between 210 g / m2 and 280 g / m2, between 220 g / m2 and 280 g / m2, between 230 g / m2 and 280 g / m2, between 240 g / m2 and 280 g / m2, between 260 g / m2 and 280 g / m2, more preferably between 210 g / m2 and 260 g / m2.

[0048] Recycling process

[0049] A recycling process relating to a material comprising PET is understood to mean a process in which at least the PET of said material is transformed to give monomers and / or oligomers which can be recovered for reuse. Step a)

[0050] Step a) of treating the material comprising PET with at least one glycol is also known as glycolysis. Glycolysis, well known to those skilled in the art, is a transesterification reaction with glycols.

[0051] The term "glycol" means an organic compound bearing two hydroxyl groups (-OH) in which the two hydroxyl groups are carried by different carbon atoms. The glycol may be selected from any glycol well known to those skilled in the art. Preferably, the glycol according to the invention is selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, butylene glycol, 1,2-butylene glycol, 1,3 butylene glycol, 1,4-butylene glycol, pentylene glycol, 3-methyl-1,5-pentanediol, neopentyl glycol, trimethylolpropane, and mixtures thereof.

[0052] In a particular embodiment of the invention, step a) is carried out by placing the material comprising PET in the presence of a mixture of at least one vegetable oil and at least one glycol. Preferably, the mixture of at least one oil vegetable oil and at least one glycol is a 90 / 10, 80 / 20, 75 / 25, 70 / 30, 65 / 35, 60 / 40, 55 / 45, or 50 / 50 mixture of vegetable oil / glycol. The vegetable oil can be chosen from any vegetable oil well known to those skilled in the art and is preferably castor oil. Advantageously, the use of a vegetable oil has the effect of reducing the quantity of glycol required for the reaction and increasing the biosourced percentage of the polyols thus obtained.

[0053] Preferably, the PET / glycol ratio is between 0.5 / 20 and 1 / 5, the ratio is for example 0.5 / 18, 0.5 / 15, 0.5 / 12, 0.5 / 10, 1 / 20, 1 / 19, 1 / 18, 1 / 17, 1 / 16, 1 / 15, 1 / 14, 1 / 13, 1 / 12, 1 / 10, 1 / 8, 1 / 6, 1 / 5.

[0054] Preferably, the glycol is introduced in excess, more preferably in excess of 5 to 20% relative to the necessary quantity of glycol. This excess of glycol makes it possible to promote the depolymerization reaction of the PET.

[0055] Preferably, step a) is carried out in the presence of a catalyst. The catalyst may be selected from any suitable catalyst well known to those skilled in the art. Preferably, the catalyst is selected from the group consisting of potassium acetate, zinc acetate, sodium acetate, calcium acetate, ammonium acetate, phosphinic acid, sulfuric acid, hydrochloric acid, dibutyltin dilaurate, n-butyltin oxide, n-butyltin hydroxide oxide, diethylamine, monoethanolamine, and barium acetate.

[0056] The amount of catalyst is preferably between 0.005 and 5% (m / m) of catalyst relative to the total mass of PET in the material, for example 0.01 to 1%, 0.02 to 0.7%, 0.05% to 1%, 0.05% to 1.5%, 0.05% to 2% (m / m). The catalyst is preferably added in excess to the reaction medium. Preferably, the catalyst is introduced in excess at a level of 0.5 to 1% relative to the necessary amount of catalyst. Some materials may contain acid, such as phosphinic acid. It has been observed that phosphinic acid helps to catalyze the reaction and that the catalyst neutralizes the acid. Therefore, adding the catalyst in excess makes it possible to compensate for the loss of an amount of catalyst used to neutralize the acid.

[0057] Step a) according to the invention is preferably carried out at a temperature ranging from 150°C to 260°C, for example from 160°C to 250°C, from 180°C to 250°C, from 190°C to 245°C, and from 200°C to 240°C. The heating may be carried out at approximately 160°C, 180°C, 200°C, 220°C, 240°C, or 260°C, each value being able to constitute an upper or lower limit of a temperature range.

[0058] Preferably, step a) according to the invention is carried out for a duration of between 10 minutes and 10 hours, preferably between 30 minutes and 8 hours, for example between 1 hour and 8 hours, between 1 hour and 7 hours, between 1 hour and 6 hours, between 1 hour and 5 o'clock, between 1 o'clock and 4 o'clock, between 1 o'clock and 3 o'clock, between 1 o'clock and 2 o'clock, between 45 minutes and 2 o'clock, between 30 minutes and 2 o'clock.

[0059] According to one embodiment of the invention, step a) can be schematized as follows:

[0060] [Chem.2]

[0061] where - n represents the number of diester units in the PET and m is equal to 1 or 2; - R represents a linear or branched alkyl chain comprising 2 to 6 atoms of carbon, the alkyl chain being able to include one or two ether functions.

[0062] Preferably, HO-R-OH is introduced in excess. The reaction can be carried out in the presence of a catalyst as described above.

[0063] Preferably, the compound of formula HO-R-OH is a glycol. More preferably, the compound of formula HO-R-OH is a glycol selected from the group consisting of the glycols cited above.

[0064] As an example, the R group can be selected from the group consisting of the substituents present in the following Table 1:

[0065] [Tables 1] [Chem 3] f -■ J- ? [Chem 4] ^-ch2 -ch3—o -ch2 -ch2 4 [Chem 5] ÇtL CH —CHâO “CH2 "CH —| [Chem 6] |—ÇH2-ÇH2 —O —CH 2 / --0 —CH^ [Chei 4—C ? n7] Hr~CHr'€H2-a [Chem 8] çh3 - CH—C [Chem 9] [Chem 10] .. CHS ï—CH—CH? 4 é $ [Chem 11] |—CH2-aH2—ch2-ch?^ [Chem 12] CH —-CH—CH? 4 f' X' s.< [Chem 13] [Chem 14] H3G ÇH3 Step b)

[0066] Step b) of treating the at least one polyol obtained with at least one dicarboxylic acid comprising from 2 to 21 carbon atoms is also known as Fisher esterification. As used herein, Fischer esterification, well known to those skilled in the art, is the reaction between a hydroxyl group and a carboxylic acid function and gives rise to the formation of an ester group and water.

[0067] During step b) according to the invention, one of the ends of the polyol obtained reacts with the at least one dicarboxylic acid resulting in a new polyol with a longer carbon chain. Advantageously, this step has the effect of reducing the hydroxyl number of the at least one polyol according to the invention. Preferably, the water is removed from the reaction medium as it is formed. For example, Water can be removed by distillation or condensation.

[0068] The expression "dicarboxylic acid" is equivalent to the expression "dicar-boxylic acid" and refers to organic compounds having two carboxyl functions. The dicarboxylic acid according to the invention can be chosen from any dicarboxylic acid well known to those skilled in the art. Preferably, the at least one dicarboxylic acid according to the invention comprises at least one bio-sourced dicarboxylic acid. The term "bio-sourced dicarboxylic acid" means a dicarboxylic acid derived from renewable biological resources. The renewable biological resources can be of plant, animal, fungal or microbial origin. As an example of a bio-sourced dicarboxylic acid, it is possible to cite succinic acid. The use of a bio-sourced dicarboxylic acid has the effect of increasing the bio-sourced percentage of the polyols obtained.

[0069] Preferably, the dicarboxylic acid according to the invention is selected from the group consisting of oxalic acid, propanedioic acid, butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, nonadioic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentanedecanedioic acid, hexadecanedioic acid, and a mixture thereof.

[0070] Step b) according to the invention is preferably carried out at a temperature ranging from 160°C to 260°C, for example from 180°C to 260°C; from 190°C to 240°C, from 200°C to 230°C, from 200°C to 225°C, from 200°C to 220°C, from 200°C to 215°C, and from 200 to 210°C. The heating may be carried out at approximately 160°C, 180°C, 200°C, 220°C, 240°C, or 260°C, each value being able to constitute an upper or lower limit of a temperature range.

[0071] Preferably, step b) according to the invention is carried out for a period of between 10 minutes and 10 hours, preferably between 30 minutes and 8 hours, for example between 1 hour and 8 hours, between 1 hour and 7 hours, between 1 hour and 6 hours, between 1 hour and 5 hours, between 1 hour and 4 hours, between 1 hour and 3 hours, between 1 hour and 2 hours, between 45 minutes and 2 hours, between 30 minutes and 2 hours.

[0072] Step b) can be schematized as follows:

[0073] [Chem. 15]

[0074] where

[0075] m is equal to 1 or 2,

[0076] R is as defined above for step a), and

[0077] R1 represents an alkyl chain having from 2 to 21 carbon atoms.

[0078] Preferably, the dicarboxylic acid of formula HOOC-R'-COOH is as defined above.

[0079] Filtration, neutralization, distillation, solubilization

[0080] Preferably, the method according to the invention further comprises a filtration step after step b). Filtration and filtration equipment are well known to those skilled in the art. By way of example, it is possible to cite drum filters, disc filters, bag filters, membrane filters, etc. Preferably, the filtration is carried out using a bag filter. Preferably, the pore size, in particular of the filter bags, is between 10 and 800 qm, more preferably the pore size is about 10 qm, about 50 qm, about 100 qm, about 150 qm, about 200 qm, about 250 qm, about 300 qm, about 350 qm, about 400 qm, about 450 qm, or about 500 qm.

[0081] The process according to the invention may also comprise a neutralization step after step b). The neutralization step may take place before or after the filtration step when the process comprises such a step. Preferably, this step is carried out in the presence of a strong base such as sodium hydroxide or potassium hydroxide or a weak base such as potassium carbonate. Preferably, this step makes it possible to reduce the acid number of the polyol.

[0082] The process according to the invention may also comprise a distillation step. The distillation may be carried out as the reaction progresses. It may also be carried out immediately after step b) or after the filtration step or even after the neutralization step. The distillation may be carried out according to any technique well known to those skilled in the art. By way of example, simple distillation and fractional distillation may be mentioned. Preferably, the distillation step makes it possible to decrease the acid number and the hydroxyl number of the polyol as well as the water content.

[0083] When the material comprises elastane, a solid layer can be observed on the surface of the mixture at the end of steps a) and / or b). The polyol is in the liquid state under this layer. Without being bound by a particular theory, it seems that the solid layer comes from the partial polymerization of the elastane and it is preferable to eliminate this solid layer.

[0084] In a particular embodiment of the invention, the solid layer is removed during the filtration step described above.

[0085] In a particular embodiment of the invention, the solid layer is removed by solubilizing the polyol and the solid layer in a solvent. Preferably, the solvent is selected from the group consisting of propylene carbonate and acetone. A filtration step may take place after the solubilization step. Preliminary steps

[0086] The method according to the invention may comprise a step of collecting and transporting the materials comprising PET to a recycling plant. Advantageously, the collection makes it possible to collect a sufficient quantity of materials comprising PET for the recycling process to be profitable.

[0087] The method according to the invention may also comprise a step of sorting the materials comprising PET according to their chemical composition.

[0088] Preferably, the method according to the invention does not comprise a step of sorting the materials comprising PET, in particular fabrics, according to their composition.

[0089] Preferably, the method according to the invention comprises a step of grinding the material comprising PET before step a). The grinding makes it possible to obtain fragments of material. The grinding can be carried out by any method well known to those skilled in the art. By way of example, it is possible to cite mechanical grinding consisting of reducing the size of the material using mechanical forces such as knife mills, hammer mills, ball mills, etc. Advantageously, the ground material will reach the melting point more quickly than the unground materials, this has the effect of improving the reaction yield, reducing the reaction time and producing more polyols in a shorter time.

[0090] The method may also comprise at least one humidification step. This step is preferably carried out on the ground material (crushing then humidification) and makes it possible to improve the handling of the material.

[0091] The method according to the invention may also comprise at least one drying step. This step makes it possible to eliminate the moisture present. Drying is preferably carried out on the crushed and / or compacted material. Drying may take place after the humidification step (grinding then humidification then drying) or before the humidification step (grinding then drying then humidification) or before and after the humidification step of the ground material (grinding then drying then humidification then drying).

[0092] The method may also comprise a step of compacting the fragments of material obtained during grinding. Counting makes it possible to further reduce the volume of the ground material. Preferably, compacting is carried out after the grinding, humidification and drying steps described above. Compacting may be carried out by any compacting technique well known to those skilled in the art. Examples include extrusion, granulation, baling presses, screw compactors, hydraulic compactors, roller compactors, and piston compactors. Preferably, the compacted material is in the form of flakes, granules or pellets.

[0093] Preferably, the recycling method according to the invention does not include a step of separating the constituents of the material comprising PET. The material comprising PET according to the invention, in particular the fabric, is subjected to the recycling method in its entirety, that is to say with all of these constituents. Thus, the material can be subjected to the recycling method, in particular to the crushing and possibly compacting steps followed by steps a) and b) directly after its collection and / or its transport to a recycling plant.

[0094] Polyol

[0095] The terms "polyol" and "polyalcohol" may be used interchangeably. Polyol means an organic compound comprising at least two hydroxyl (-OH) groups.

[0096] The polyol obtained or capable of being obtained by the process of recycling a material comprising PET according to the invention can be described as recycled polyol.

[0097] The polyol obtained or capable of being obtained by the process for recycling a material comprising PET according to the invention is preferably a mixture of polyester polyol, and more preferably an aromatic polyester polyol. The term "polyester polyol" means a polyol comprising ester bonds. When the polyester polyol is aromatic, it comprises aromatic units in its structure.

[0098] The polyol according to the invention is in the liquid state at a temperature below 80°C such as for example at 75°C, 70°C, 65°C, 60°C, 55°C, 50°C, 45°C, 40°C, 35°C, 30°C, 25°C and 20°C.

[0099] Typically, the polyol according to the invention has a viscosity greater than 200 cP, greater than 300 cP, greater than 400 cP, greater than 500 cP, greater than 600 cP, greater than 700 cP, greater than 800 cP, greater than 900 cP, greater than 1000 cP, greater than 1500 cP, greater than 2000 cP, greater than 2500 cP, greater than 3000 cP, greater than 3500 cP, greater than 4000 cP, greater than 4500 cP, greater than 5000 cP, greater than 5500 cP, greater than 6000 cP, greater than 6500 cP, greater than 7000 cP, greater than 7500 cP, greater than 8000 cP, greater than 8500 cP, greater than 9000 cP, greater than 9500 cP, measured at 25°C at 100 rpm. Preferably, the polyol according to the invention has a viscosity of between 200 and 10000 cP, for example between 200 and 9000 cP, 200 and 8000 cP, 200 and 7000 cP, 200 and 6000 cP, 200 and 5000 cP, 200 and 4000 cP, 200 and 3000 cP, 200 and 2000 cP, 200 and 1000 cP, 500 and 10000 cP, 500 and 9000 cP, 500 and 8000 cP, 500 and 7000 cP, 500 and 6000 cP, 500 and 5000 cP, 500 and 4000 cP, 500 and 3000 cP, 500 and 2000 cP, 500 and 1000 cP, measured at 25°C at 150 rpm for 30 seconds. Viscosity can be measured by any method well known to those skilled in the art. For example, a Brookfield viscometer can be used at 150 rpm for approximately 30 seconds at 25°C.

[0100] The term "acid number" means the mass of potassium hydroxide (KOH), expressed in milligrams, necessary to neutralize the free acidity contained in one gram of fatty substance. Briefly, the acid number is determined by a back titration. The fatty substance reacts with a known excess of alcoholic potassium hydroxide. The excess KOH is then titrated with a hydrochloric acid solution. The fatty substance is dissolved in a neutral organic solvent. The acid number of the polyol according to the invention can be measured according to the European standard NF EN ISO 660: 2009. Preferably, the polyol according to the invention has an acid number of between 0.1 and 10 mg KOH / g, for example between 0.1 and 8 mg KOH / g, 0.1 and 5 mg KOH / g, and 0.1 and 2 mg KOH / g. More preferably, the acid number of the polyol according to the invention is less than 1 mg KOH / g, for example less than 0.5 mg KOH / g.

[0101] The hydroxyl number corresponds to the quantity of hydroxyl groups (-OH) present in a molecule or substance. The hydroxyl number is generally expressed in milligrams of potassium hydroxide (KOH) equivalent per gram of substance (mg KOH / g). This measurement indicates the number of milligrams of potassium hydroxide that would be required to neutralize all the hydroxyl groups. The hydroxyl number can be measured by any method well known to those skilled in the art, such as acid-base titration, infrared spectroscopy, and high-performance liquid chromatography (HPLC). The hydroxyl number can be determined by inverse titration using potassium hydroxide, for example, according to ASTM 4274-99 in which the colorimetric titration is replaced by a pH-metric titration.

[0102] Preferably, the polyol according to the invention has a hydroxyl index compatible with a sprayed polyurethane foam formulation.

[0103] Preferably, the polyol according to the invention has a hydroxyl number of less than 400 mg KOH / g, preferably less than 380 mg KOH / g, more preferably less than 320 mg KOH / g. More preferably, the polyol according to the invention has a hydroxyl number of between 140 and 350 mg KOH / g, for example between 150 and 320 mg KOH / g, 160 and 310 mg KOH / g, 160 and 300 mg KOH / g, 160 and 295 mg KOH / g, 160 and 290 mg KOH / g, 160 and 285 mg KOH / g, 160 and 280 mg KOH / g, 160 and 275 mg KOH / g, and 160 and 270 mg KOH / g.

[0104] Typically, the polyol according to the invention has a molecular mass of between 350 g / mol and 2000 g / mol, preferably between 420 g / mol and 1800 g / mol, more preferably between 450 g / mol and 1700 g / mol. The molecular mass of the polyol can be determined by any method well known to those skilled in the art such as, for example, size exclusion chromatography.

[0105] The “bio-sourced percentage of polyol” designates the proportion of raw materials of biological origin used in the production of the polyol. In other words, this percentage indicates the share of renewable raw materials in relation to the total raw materials used in the manufacture of the polyols. The bio-sourced percentage of the polyol according to the invention is preferably between 1 and 50%, for example between 5 and 50%, between 5 and 45%, between 5 and 40%, between 5 and 35%, between 5 and 30%, between 5 and 25%, between 5 and 20%, between 5 and 15%, and between 5 and 10%.

[0106] Use of polyol

[0107] The polyol according to the invention can be used immediately after its production or it can be stored or transported. The polyol according to the invention is stable when stored in containers that are preferably airtight and moisture-proof. The polyol can be stored in plastic or stainless steel containers, drums, cans. Typically, the polyol is stable at a temperature between 1°C and 30°C for a period of at least 1 year.

[0108] Additives may be added to the polyol according to the invention. As examples of additives that may be added, it is possible to cite surfactants, silicone-based surfactants, plasticizers, chain extenders, etc.

[0109] Typically, the amount of silicone-based surfactant that can be added is between 0.5 and 10% (m / m) relative to the total mass of polyol, for example between 0.5 and 9%, 1 and 8%, or 2 and 7% (m / m). The amount of plasticizer that can be added is between 1 and 50% (m / m) relative to the total mass of polyol, for example between 1 and 25%, 1 and 15%, and 10%, 1 and 5% (m / m). The amount of chain extender that can be added is preferably between 0.1 and 20% (m / m) relative to the total mass of polyol, for example between 1 and 15%, 1 and 10%, 5 and 10%, 2 and 5% (m / m).

[0110] The polyol according to the invention is particularly suitable for the manufacture of polyurethane and polyisocyanurate materials, in particular rigid and flexible foams, insulators, elastomers, coatings and adhesives.

[0111] A polyurethane is a polymer comprising methane functions. These polymers, well known to those skilled in the art, essentially result from the reaction of polyol, in particular the recycled polyol according to the invention, and polyisocyanates.

[0112] A polyisocyanurate is a polymer well known in the art composed primarily of polymer chains formed by the reaction between polyols and isocyanates. Typically, 1 volume of polyol is mixed with about 3 volumes of isocyanate to obtain the polyisocyanurate.

[0113] One embodiment of the invention therefore relates to a composition comprising the polyol obtained or capable of being obtained by a process for recycling a material comprising PET as defined in the present description and which is capable of forming foams, elastomers, adhesives, insulators and coatings after polymerization. In particular, an example of a composition according to the invention comprises at least one polyol according to the invention and at least one polyisocyanate.

[0114] The polyisocyanates that can be used are well known to those skilled in the art and preferably include aromatic, aliphatic and cycloaliphatic polyisocyanates. Preferably, the polyisocyanate is selected from the group consisting of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), naphthalene diisocyanate (NDI), trimethyl or tetramethylhexamethylene diisocyanate (TMDI), cyclohexane diisocyanate (CHDI), xylylene diisocyanate (XDI) and a mixture thereof.

[0115] The polyurethane and the polyisocyanurate may be obtained from the recycled polyol according to the invention as the sole source of polyol. The polyurethane and the polyisocyanurate may also be obtained from a polyol mixture comprising the polyol according to the invention and at least one other non-recycled polyol. The at least one other polyol may be chosen from any suitable polyol well known to those skilled in the art such as polyether polyols, aliphatic polyester polyols, aromatic polyester polyols, polycarbonate polyols, etc. Preferably, the polyol mixture comprises at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 60% (m / m) of recycled polyol according to the invention relative to the total mass of polyol.Preferably, the polyol mixture comprises between 25% and 99.9% (m / m) of recycled polyol according to the invention relative to the total mass of polyol, for example between 25% and 95%, between 25% and 90%, between 25% and 85%, between 25% and 80%, between 25% and 75%, between 25% and 70%, between 25% and 65%, between 25% and 60%, and between 25% and 50% (m / m).

[0116] The term “foam” means a compound with a three-dimensional cellular structure of the expanded type. Said foam may be rigid or flexible, with open or closed cells. Closed-cell foams are foams whose cellular structure includes walls between each cell, forming a set of joined and separate cells that allow the entrapment of an expanding gas. Open-cell foams are foams whose cellular structure consists of a continuous cellular matrix with open walls between the cells, which does not allow the entrapment of an expanding gas. Rigid polyurethane or polyisocyanurate foams can be used as insulating materials due to their generally low thermal conductivity. These foams can be used, for example, for the insulation of exterior walls of residential and commercial buildings, shipping containers, etc.Polyurethane or polyisocyanurate foams can be obtained by blending the polyurethane or polyisocyanurate polymer with foaming agents, catalysts, stabilizers, blowing agents and other additives.

[0117] The term “elastomer” means a material having elastic properties which can undergo large deformations and return to its initial state without loss of properties.

[0118] The term “coating” means a material intended to cover a surface for its protection; it may, for example, be thin and resistant or thick in order to absorb shocks.

[0119] By “adhesive” or “adhesive composition” is meant a composition allowing adhesion between two compounds, surfaces or objects.

[0120] Advantageously, the polyol according to the invention provides improvements to the polyurethane or polyisocyanurate materials derived therefrom, in particular in terms of fire resistance, adhesion, and impact resistance. EXAMPLES 1. Example 1

[0121] The inventors recycled fabrics comprising PET using the recycling method according to the invention and evaluated the effects related to the change in the dicarboxylic acid.

[0122] The collected fabric comprises between 75 and 85% PET, between 8 and 12% elastane, between 5 and 10% of a flame retardant and approximately 1% of an additive.

[0123] The fabric was subjected to a grinding step in order to obtain fabric fragments followed by the steps of humidification, drying and compaction so as to form granules of material.

[0124] The granules were subjected to a glycolysis step with diethylene glycol in the presence of an excess of 0.3% to 1% of a catalyst at a temperature of between 200°C and 260°C and then to an esterification step with adipic acid at a temperature temperature between 200°C and 230°C. Water was removed by distillation as it formed.

[0125] The polyol was obtained in the form of a viscous liquid. A solid layer was formed on the surface of the polyol. In order to remove the solid layer, the polyol and the solid layer were solubilized in acetone and then filtered using a bag filter with a porosity of 10 qm or more.

[0126] The polyol obtained has a hydroxyl index of between 260 and 307 mg KOH / g, which is compatible with use in the formulation of sprayed polyurethane foam.

[0127] In order to evaluate the influence of the change of dicarboxylic acid on the preparation of the polyol. The process was repeated by changing the adipid acid with a bio-sourced succinic acid.

[0128] The polyol obtained has a hydroxyl index of 313 mg KOH / g which is compatible with use in the formulation of sprayed polyurethane foam.

[0129] The polyol obtained with the bio-sourced acid was then introduced into a foam formula and made it possible to obtain a foam with a three-dimensional cellular structure of the expanded type whose appearance and formation kinetics are comparable to a foam obtained from petro-sourced polyols (see Table 2 below).

[0130] [Table 2]: Foam formation kinetics Time Foam based on petroleum-sourced polyols Foam based on recycled polyols (according to the invention) Cream 1 2 Gel 7 9 Rise 17 23 Tack-free 8 11

[0131] The terms cream, gel, rise and tack-free are used to describe the different phases of formation of expanded polyurethane foam. - “Cream” corresponds to the beginning of the foam formation process When the two components (polyols and isocyanate) are mixed, a light, airy foam is formed. - “Gel” corresponds to the moment when a gel structure begins to form, the foam begins to take on a more solid consistency but remains soft and malleable. - “Rising” is the stage that occurs when the foam begins to expand and increase in volume due to the formation of gas, usually carbon dioxide, which is produced as a by-product of ongoing chemical reactions. The foam continues to expand until reach its desired final size. - “Tack-free” is the stage during which the surface of the foam becomes non-sticky. sticky. It can be handled or touched without sticking to the fingers. 2. Example 2

[0132] The inventors proceeded to the recycling of fabrics comprising mainly PET.

[0133] The composition of the collected tissues is presented in Table 3 below:

[0134] [Table 3]: composition of tissues PET fabric (%) Flame retardant (%) Additive (%) A 94 5 1 B 93 6 1 C 94 5 1

[0135] Each fabric underwent an independent recycling process. Each fabric was ground to obtain fabric fragments, moistened, dried and compacted to obtain fabric pellets.

[0136] The granules were subjected to a glycolysis step with diethylene glycol at a temperature between 200 and 260°C and then to an esterification step with adipic acid at a temperature between 200 and 230°C. The water was removed by distillation as it was formed. The reaction was carried out without a catalyst.

[0137] The polyol in the form of a viscous liquid was filtered using a bag filter with a porosity of 10 qm or more. The polyols obtained have hydroxyl numbers between 274 and 293, which is compatible with use in the formulation of sprayed polyurethane foam.

[0138] The polyols were then introduced into expanded type polyurethane foam formulas, which made it possible to obtain foams with a three-dimensional cellular structure whose appearance and formation kinetics are comparable to the foams obtained from polyols derived from petrochemicals (see Table 4 below).

[0139] [Table 4]: Foam formation kinetics Time Foam based on petroleum-sourced polyols Foam based on recycled polyols (according to the invention) Cream 1 0-2 Gel 7 8 Rise 17 22 Tack-free 8 9-10 3. Example 3

[0140] The inventors applied the recycling process of the invention to a mixture of three different types of fabrics.

[0141] The fabrics used included between 78 and 96% PET, between 3 and 15% of a flame retardant and approximately 1% of an additive.

[0142] The fabric mixture was subjected to a grinding step followed by humidification, drying and compacting steps so as to form granules of material.

[0143] The granules were subjected to a glycolysis step with diethylene glycol in the presence of an excess of 0.3% to 1% of a catalyst at a temperature of between 200°C and 260°C and then to an esterification step with adipic acid at a temperature of between 200°C and 230°C. The water was removed by distillation as it was formed.

[0144] The polyol was obtained in the form of a viscous liquid. A solid layer was formed on the surface of the polyol. In order to remove the solid layer, the polyol and the solid layer were solubilized in acetone and then filtered using a bag filter with a porosity of 10 qm or more.

[0145] The polyol obtained was introduced into expanded type polyurethane foam formulas, which made it possible to obtain foams with three-dimensional cellular structures whose appearance and formation kinetics are comparable to foams obtained from polyols derived from petrochemicals (see Table 5 below).

[0146] [Table 5]: Foam formation kinetics Time Foam based on petroleum-sourced polyols Foam based on recycled polyols from the mixture of several fabrics (according to the invention) Cream 1 1 Gel 7 6 Rise 17 17 Tack-free 8 7 4. Conclusion

[0147] The fabric recycling process implemented makes it possible to address the problem of recycling fabrics used in the world of events. In addition, the process implemented makes it possible to obtain polyols, by simple chemical synthesis without prior separation of the different constituents of the fabric. Finally, the polyols obtained are suitable for use in the manufacture of polyurethane foams with excellent properties. This process therefore makes it possible to reduce the proportion of petroleum-sourced material in polyurethane polymers, particularly polyurethane insulation.

Claims

Claims

1. A method of recycling a material comprising polyethylene terephthalate (PET), comprising: a) a step of treating the material, optionally previously ground, with at least one glycol comprising from 2 to 10 carbon atoms to obtain at least one polyol; b) a step of treating at least one polyol obtained with at least one dicarboxylic acid comprising from 2 to 21 carbon atoms in order to reduce the hydroxyl number of the at least one polyol.

2. The method of claim 1, wherein the material comprises at least 50% (m / m) PET.

3. A method according to claim 1 or 2, wherein the material comprises from 1% (m / m) to 50% (m / m) elastane.

4. A method according to any one of claims 1 to 3, wherein the material comprises a flame retardant.

5. Method according to one of claims 1 to 4, in which the material comprises a coating selected in particular from the group consisting of acrylic, polyurethane, epoxy, polyethylene, polyvinyl chloride, polyvinylidene chloride, silicone, fluoropolymer such as polytetrafluoroethylene, ethylene tetrafluoroethylene, fluorinated ethylene propylene, wax, latex, nylon and mixtures thereof.

6. A method according to any one of claims 1 to 5, wherein the material is a fabric.

7. A method according to any one of claims 1 to 6, further comprising a step of crushing and compacting the material before the step

8. dj. A method according to any one of claims 1 to 7, further comprising a filtration step after step b.

9. The method of any one of claims 1 to 8, wherein the at least one glycol is selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, and mixtures thereof.

10. A method according to any one of claims 1 to 9, wherein the at least one dicarboxylic acid comprises at least one bio-sourced dicarboxylic acid.

11. A method according to any one of claims 1 to 10, wherein the at least one dicarboxylic acid is selected from the group consisting of oxalic acid, propanedioic acid, butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, nonadioic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentanedecanedioic acid, hexadecanedioic acid, and a mixture thereof.

12. A method according to any one of claims 1 to 10, wherein step a) is carried out in the presence of a catalyst, in particular selected from the group consisting of potassium acetate, zinc acetate, sodium acetate, calcium acetate, ammonium acetate, phosphinic acid, sulfuric acid, hydrochloric acid, dibutyltin dilaurate, n-butyltin oxide, n-butyltin hydroxide oxide, diethylamine, monoethanolamine, and barium acetate.

13. Polyol obtained or obtainable by a process for recycling a material comprising polyethylene terephthalate (PET) as defined in any one of claims 1 to 12.

14. Use of a polyol obtained or obtainable by a process for recycling a material comprising polyethylene terephthalate (PET) as defined in any one of claims 1 to 12, for the preparation of a polyurethane foam, a polyisocyanurate foam, an elastomer, or an adhesive.