Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/02—Separating plastics from other materials
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/06—Recovery or working-up of waste materials of polymers without chemical reactions
  • C08J11/08—Recovery or working-up of waste materials of polymers without chemical reactions using selective solvents for polymer components
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/02—Separating plastics from other materials
  • B29B2017/0213—Specific separating techniques
  • B29B2017/0293—Dissolving the materials in gases or liquids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/04—Polymers of ethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/04—Polymers of ethylene
  • B29K2023/06—PE, i.e. polyethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/04—Polymers of ethylene
  • B29K2023/08—Copolymers of ethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/10—Polymers of propylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/10—Polymers of propylene
  • B29K2023/12—PP, i.e. polypropylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/10—Polymers of propylene
  • B29K2023/14—Copolymers of polypropylene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/04—Homopolymers or copolymers of ethene
  • C08J2323/06—Polyethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/10—Homopolymers or copolymers of propene
  • C08J2323/12—Polypropene
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/20—Waste processing or separation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/62—Plastics recycling; Rubber recycling

Definitions

• the present invention relates to a process for recycling used plastics in order to obtain a flow of purified thermoplastic polymers which can be used for example in the manufacture of new plastic objects. More particularly, the present invention relates to a process for purifying a plastic filler, in particular from plastic waste, comprising thermoplastic polymers, in particular polyolefins, said process comprising the dissolution of the thermoplastic polymers in a light hydrocarbon solvent, in particular based on of alkane(s) having a boiling point between - 15°C and 100°C, at least one step of purification of the polymer solution obtained, in order to eliminate at least in part the impurities, in particular the additives conventionally used in plastic-based materials, and an optimized step of separation of the polymer and the solvent in order to recover purified thermoplastic polymers, so as to be able to reuse the purified thermoplastic polymers recovered and thus valorize the plastic filler.
• Plastics from collection and sorting channels can be recycled according to different channels.
• mechanical recycling makes it possible to partially reuse certain waste either directly in new objects or by mixing mechanically sorted plastic waste streams with virgin polymer streams. This type of recovery is limited since mechanical sorting makes it possible to improve the purity of a flow of a given type of polymer, but generally it does not make it possible to sufficiently eliminate the impurities which are at least partly trapped in the polymer matrix.
• additives such as fillers (or “fillers” according to Anglo-Saxon terminology), dyes, pigments, and metals.
• So-called chemical recycling aims to reform at least partly monomers according to a generally complex sequence of steps.
• plastic waste can undergo a pyrolysis step, and the pyrolysis oil recovered, generally after purification, can be converted at least in part, for example, into olefins by steam cracking. These olefins can then be polymerized.
• This type of sequence can be adapted for poorly sorted loads or refusals from sorting centers, but it generally requires significant energy consumption due in particular to high temperature treatments.
• Another way of recycling plastic waste consists of putting plastics, in particular thermoplastics, into solution, at least in part, with a view to purifying them by eliminating polymers from the load other than those targeted and/or impurities. , for example additives such as fillers or fillers according to Anglo-Saxon terminology, dyes, pigments, and metals.
• Document US 2017/0021 10 describes a particular method for purifying a polymer filler in particular from plastic waste, by dissolving the polymer in a solvent, under particular conditions of temperature and pressure, then contacting the polymer solution obtained with a solid.
• Document WO 2018/114047 proposes a method for dissolving a plastic in a solvent at a dissolution temperature close to the boiling temperature of the solvent.
• the process of document WO 2018/114047 does not make it possible to effectively treat impurities other than polymers.
• Document US 2018/0208736 proposes a treatment process by liquefaction of thermoplastics in a solvent then separation of insolubles and/or gases. The process of document US 2018/0208736 does not make it possible to effectively treat impurities soluble in the solvent.
• the present invention aims to overcome these drawbacks and contribute to the recycling of plastics. More particularly, it aims to propose an effective, simple and economically viable process for treating a plastic load in particular from plastic waste, in order to eliminate at least in part the impurities it contains, in particular at least in part the additives it contains and which are conventionally added to plastic materials, so as to be able to recover said plastic filler and more particularly plastic waste.
• the present invention in fact seeks to effectively separate impurities from thermoplastics, and in particular polyolefins, which used plastic materials include and to recover purified thermoplastic polymers, and in particular polyolefins, to be able to use them for example as a polymer base. in the manufacture of new plastic objects, particularly instead of virgin resin.
• the invention relates to a process for purifying a plastic filler, said method comprising: a) a dissolution step comprising bringing the plastic filler into contact with a dissolution solvent comprising at least one hydrocarbon compound having a boiling temperature between -15 and 100°C, at a dissolution temperature between 120°C and 250°C, and a dissolution pressure between 1.0 and 25.0 MPa absolute, to obtain at least one solution raw polymer; b) a step of purifying the raw polymer solution to obtain a purified polymer solution, comprising: b1) a sub-step of separating the insolubles; and/or b2) a washing sub-step, by contact with a dense solution; and/or b3) an extraction sub-step, by contact with an extraction solvent; and/or b4) a sub-step of adsorption of impurities by contact with an adsorbent; then c) a solvent-polymer separation step, using at least one supercritical separation section operated at a temperature between 160 and 300°C
• the advantage of the process of the invention is to provide a process for effective treatment of a load comprising plastics and in particular plastic waste in particular from collection and sorting sectors, so as to recover thermoplastic polymers, and in particular polyolefins, which it contains so that they can be recycled for all types of applications.
• the process according to the invention makes it possible to obtain a flow of purified thermoplastics, advantageously comprising contents of impurities, in particular of additives, and of solvent, in particular of dissolution solvent, negligible or at least sufficiently low so that the Streams of purified thermoplastic polymers can be introduced into all types of plastic formulations in place of virgin resin.
• the flow of purified thermoplastics, and in particular the flow of purified polyolefins, obtained at the end of the process according to the invention advantageously comprises less than 5% by weight of impurities, very advantageously less than 1% by weight of impurities and very advantageously less than 5% by weight of solvent (in particular dissolution solvent), preferably less than 1% by weight of solvent, preferably less than 0.1% by weight of solvent.
• solvent in particular dissolution solvent
• the process according to the invention thus provides a simple diagram corresponding to a sequence of operations, which makes it possible to rid plastic waste of at least part of its impurities, in particular at least part of the additives, and to recover purified thermoplastic polymers, advantageously comprising little or no solvent, so as to be able to recover plastic waste by recycling said purified thermoplastics.
• the additives present in the plastic filler can be soluble or insoluble in the solvent used throughout the process according to the invention, allowing effective purification and separation of the polymers.
• the process according to the invention proposes a sequence of operations implemented under operating conditions, in particular optimal temperatures and pressure, to effectively separate impurities and solvents from thermoplastic polymers, but reasonable, thus limiting energy consumption. of the process and, therefore, making said process economically interesting.
• the invention also has the advantage of participating in the recycling of plastics and the preservation of fossil resources, by allowing the recovery of plastic waste. It allows, in fact, the purification of plastic waste with a view to obtaining fractions of purified thermoplastic polymers, in particular purified polyolefins, with a reduced content of impurities, in particular decolorized and deodorized thermoplastic fractions, which can be reused to form new plastic objects.
• the purified thermoplastic fractions obtained can thus be used directly in formulations mixed with additives, for example dyes, pigments, other polymers, instead of or mixed with virgin resins, with a view to obtaining plastic products with useful, aesthetic, mechanical or rheological properties facilitating their reuse and recovery.
• the present invention also makes it possible to separate effectively, and advantageously at lower cost, the targeted thermoplastic polymers from the solvent used (in particular the dissolving solvent), while limiting the thermal degradation of the targeted thermoplastic polymers.
• the solvent used to treat the plastic filler, in particular the dissolution solvent is recovered at least in part, and can be recycled to one of the stages of the process, which makes it possible to avoid excessive consumption of solvent, hence the ecological and economic interest of the process.
• the present invention aims to purify a plastic filler, in particular plastic waste, to obtain purified thermoplastic polymers and more particularly purified polyolefins, so as to be able to use them in any application in particular as a replacement for virgin resins.
• the present invention aims to propose a process comprising a dissolution step followed by at least one purification step then an optimized solvent/polymer separation, to obtain a flow of purified thermoplastic polymers.
• the expressions "between ... and " and “between .... and " are equivalent and mean that the limit values of the interval are included in the range of values described . If this is not the case and the limit values are not included in the range described, such precision will be provided by the present invention.
• the different parameter ranges for a given step such as the pressure ranges and the temperature ranges can be used alone or in combination.
• a range of preferred pressure values can be combined with a range of more preferred temperature values.
• the pressures are absolute pressures and are given in absolute MPa (or abs. MPa).
• upstream and downstream are to be understood according to the general flow of the fluid(s) or flows in question in the process.
• thermoplastic polymer and “thermoplastic” are used interchangeably.
• additives is a term conventionally used in the field of polymers and in particular in the field of polymer formulations.
• the additives introduced into the polymer formulations can be, for example, plasticizers, fillers or “fillers” according to the established Anglo-Saxon terminology (which are organic or mineral solid compounds, making it possible to modify the physical, thermal, mechanical and/or electrical polymer materials or to lower their cost price), reinforcing agents, dyes, pigments, hardeners, flame retardants, combustion retardants, stabilizing agents, antioxidants, UV absorbers, antistatic agents, etc.
• the additives correspond to at least part of the impurities of the plastic filler to be treated and which the process according to the invention makes it possible to eliminate at least in part.
• Other types of impurities may be use impurities, such as for example metal impurities, paper/cardboard, biomass, polymers other than the targeted polymer(s), etc.
• the impurities, which the process according to the invention makes it possible to eliminate at least in part include the additives conventionally used in polymer formulations and generally usage impurities resulting from the life cycle of materials and objects. plastics, and/or from the waste collection and sorting circuit.
• the latter can be metallic, organic or mineral impurities; it may be packaging residues, food residues or compostable residues (biomass).
• These use impurities may also include glass, wood, cardboard, paper, aluminum, iron, metals, tires, rubber, silicones, rigid polymers, thermosetting polymers, products household, chemical or cosmetic products, used oils, water.
• a polymer solution is a solution comprising the dissolution solvent and at least the targeted thermoplastic polymers, in particular the targeted polyolefins, dissolved, that is to say in particular solvated and dispersed, in said dissolution solvent, the dissolved thermoplastic polymers being initially present in the filler.
• the polymer solution may further comprise soluble (and solubilized in the dissolution solvent) and/or insoluble (and suspended in the polymer solution) impurities.
• said polymer solution can therefore comprise impurities in the form of insoluble particles which are advantageously suspended in said polymer solution, soluble impurities dissolved in the dissolution solvent, and/or possibly a other liquid phase immiscible with said polymer solution.
• the critical temperature and critical pressure of a solvent are specific to that solvent and depend on the chemical nature of the solvent considered.
• the critical temperature and the critical pressure of a pure body are respectively the temperature and the pressure of the critical point of said pure body.
• the pure body considered is in supercritical form or in the supercritical state; it can then be called supercritical fluid.
• the invention relates to a process for purifying a plastic filler, preferably composed of plastic waste, and advantageously comprising thermoplastic polymers, more particularly polyolefins, said process comprising, preferably consisting of: a) a dissolution step comprising the bringing the plastic filler into contact with a dissolving solvent comprising at least one advantageously aliphatic and preferably paraffinic hydrocarbon compound, having a boiling temperature of between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, very preferably between 25 and 61°C and preferably between 25 and 40°C, at a dissolution temperature between 120°C and 250°C, preferably between 130 and 225°C, preferably between 150°C and 210°C, and preferably between 150°C and 195°C, and a dissolution pressure between 1.0 and 25.0 MPa abs., preferably between 1.0 and 20.0 MPa abs., preferably between 3.0 and 18.0 MPa abs., preferably between
• At least one solvent recovery section in particular operated at a temperature between 160 and 300°C and a pressure preferably between Psupercritical and 0 .000005 MPa (i.e. 5 Pa), preferably between 2.7 MPa and 0.000005 MPa, and in particular between 1.0 MPa and 0.000005 MPa, to obtain at least one fraction of purified thermoplastic polymers, more particularly at least one purified polyolefin fraction, and advantageously a solvent fraction.
• plastic filler comprises plastics which themselves comprise more particularly thermoplastic polymers.
• the plastic filler comprises between 50 and 100% by weight, preferably between 70% and 100% by weight of plastics.
• plastics included in the load of the process according to the invention are generally production scraps and/or waste from plastic objects at the end of their life, in particular household plastic waste, plastic waste from construction, automobile plastic waste or of all types of transport or even waste electrical and electronic equipment.
• plastic waste comes from collection and sorting channels.
• Plastics or plastic materials include polymers which are mixed with additives, with a view to forming, after shaping, various materials and objects (injection molded parts, tubes, films, fibers, fabrics, putties, coatings, etc.).
• Additives used in plastics can be organic compounds or inorganic compounds. These include, for example, fillers, dyes, pigments, plasticizers, property modifiers, combustion retardants, etc.
• the filler of the process according to the invention comprises in particular thermoplastic polymers, preferably at least 50% by weight, preferably at least 70% by weight, preferably at least 80% by weight and very preferably at least 90% by weight of polymers.
• thermoplastics relative to the total weight of the plastic filler.
• the thermoplastic polymers included in the plastic filler may be alkene polymers, diene polymers, vinyl polymers and/or styrenic polymers.
• the thermoplastic polymers included in the plastic filler are polyolefins, such as polyethylene (PE), polypropylene (PP) and/or copolymers of ethylene and propylene.
• the plastic filler comprises at least 80% by weight, preferably at least 85% by weight, preferably at least 90% by weight, of polyolefins relative to the total weight of the plastic filler, the polyolefins being in particular mixtures polyolefins and/or copolymers of olefins, in particular blends of polyethylene (PE), polypropylene (PP) and/or copolymers of ethylene and propylene.
• the polyolefins of the plastic filler are not mainly composed of polyethylene (PE) or polypropylene (PP) but are in fact mixtures of polyethylene (PE) and polypropylene (PP) and/or copolymers ethylene and propylene.
• the polyolefins of the plastic filler therefore comprise less than 80% by weight of polyethylene or less than 80% by weight of polypropylene.
• the plastic filler comprises at least 80% by weight, preferably at least 85% by weight, preferably at least 90% by weight, of a mixture of polyethylene, polypropylene and/or copolymers of ethylene and propylene, the percentages being given in relation to the total weight of the plastic filler, said mixture comprising less than 80% by weight of polyethylene and less than 80% by weight of polypropylene.
• the plastic filler can therefore comprise polyethylene at a content of less than 80% by weight, preferably less than 72% by weight, preferably less than 68% by weight and preferably less than 64% by weight, and polypropylene at a content of less than 80% by weight. % by weight, preferably less than 72% by weight, preferably less than 68% by weight and preferably less than 64% by weight, the percentages being given relatively to the weight of the plastic filler treated by the process according to the invention.
• the process according to the invention thus aims in particular to purify and recover the polyolefins, in particular mixtures of polyolefins or their copolymers, contained in the filler in order to be able to reuse them in different applications.
• the plastic filler may also include impurities, such as for example polymers other than the targeted thermoplastics, additives advantageously used to formulate the plastic material and also generally use impurities resulting from the life cycle of plastic materials and objects, and /or from the waste collection and sorting circuit, all of these compounds being considered as impurities.
• the charge for the process according to the invention may comprise up to 50% by weight of impurities, preferably up to 20% by weight of impurities, preferably up to 10% by weight of impurities.
• the plastic filler may include, for example, at least 5% by weight of impurities.
• the plastic filler can advantageously be pretreated upstream of the process so as to at least eliminate all or part of the so-called coarse impurities, that is to say impurities in the form of particles of size greater than or equal to 10 mm, preferably greater than or equal to 10 mm. equal to 5 mm, or even greater than or equal to 1 mm, for example impurities such as wood, paper, biomass, iron, aluminum, glass, etc., and to shape it generally in the form of divided solids (or particles) so as to facilitate processing in the process.
• This pretreatment may include a grinding step, a washing step at atmospheric pressure and/or a drying step.
• This pretreatment can be carried out on a different site, for example in a waste collection and sorting center, or on the same site where the treatment process according to the invention is implemented.
• this pretreatment makes it possible to reduce the impurity content to less than 20% by weight, preferably less than 15% by weight, preferably less than 10% by weight, the percentages being given relatively to the weight of the filler.
• plastic treated by the process according to the invention is generally stored in the form of divided solids, for example in the form of ground material or powder, so as to facilitate handling and transport to the process.
• Step a) dissolution the process comprises a dissolution step a) in which the plastic filler is brought into contact with a dissolution solvent, to obtain at least one, preferably one, raw polymer solution.
• This step advantageously allows the dissolution of at least a part, preferably of all, of the targeted thermoplastic polymers, particularly the targeted polyolefins, which the plastic filler contains.
• thermoplastic polymers dissolved in a solvent, more particularly in the dissolving solvent.
• Those skilled in the art are well aware of the phenomena involved in the dissolution of polymers and which include at least mixing, dispersion, homogenization, solvation and disentanglement of the thermoplastic polymer chains.
• the pressure and temperature conditions make it possible to maintain the dissolution solvent, at least in part and preferably in full, in the liquid state, so as to optimize the dissolution of the targeted thermoplastics, in particular the targeted polyolefins.
• dissolution solvent advantageously allows the use of operating conditions, and in particular conditions of temperature and pressure, in particular pressure, reasonable to ensure, on the one hand, in step a) of dissolution but also advantageously in step b ) purification, maintaining the dissolution solvent in the liquid phase, at least in part, preferably entirely, thus allowing optimal dissolution of the targeted polymer(s) and advantageously effective purification of the polymer solution , and, on the other hand, in step c) of solvent-polymer separation, the transition to the supercritical state of at least a part of said dissolution solvent, to allow the demixing and therefore the separation of at least one part of the dissolution solvent, and possibly the evaporation of the residual dissolution solvent, at least in part, which thus makes it possible to achieve a very low solvent content in the thermoplastic polymers purified and recovered at the end of the process (advantageously a content of less than 5% by weight of solvent, preferably less than 1% by weight of solvent, preferably less than 0.1% by weight of solvent relative to the
• a solvent composed of very light alkanes with a boiling point lower than -15°C such as for example propane, which could be interesting in particular for its relatively mild critical conditions (temperature and pressure), would require the use of high pressure to keep the dissolution solvent at least partly, preferably entirely, in liquid form throughout the duration of steps a) dissolution and b) purification, which would entail significant costs, in particular investment.
• a heavy solvent such as alkanes with a boiling point greater than 100°C, would require very severe operating conditions in step c) to reach the critical conditions of said heavy solvent and to be able to obtain said solvent at least partly in the supercritical state.
• the dissolution solvent comprises, preferably consists of, at least one advantageously aliphatic and preferably paraffinic (that is to say saturated) hydrocarbon compound, preferably at least one alkane, having a boiling point of between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, very preferably between 25 and 61°C and preferably between 25 and 40°C.
• the dissolution solvent comprises predominantly, preferably at least 80% by weight, preferably at least 95% by weight, preferably 98% by weight, of an advantageously aliphatic, preferably paraffinic (or alkane) hydrocarbon compound (100% being the maximum, the percentages being expressed relative to the total weight of the dissolution solvent) having a boiling temperature of between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, very preferably between 25 and 61°C and more preferably between 25 and 40°C.
• an advantageously aliphatic, preferably paraffinic (or alkane) hydrocarbon compound (100% being the maximum, the percentages being expressed relative to the total weight of the dissolution solvent) having a boiling temperature of between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, very preferably between 25 and 61°C and more preferably between 25 and 40°C.
• the advantageously aliphatic, preferably paraffinic hydrocarbon compound, the majority of the dissolution solvent has a critical temperature (temperature at the critical point of said pure hydrocarbon compound) of between 130 and 285°C, preferably between 158 and 285°C, preferably between 185 and 245°C, very preferably between 185 and 230°C and more preferably between 185 and 200°C.
• the majority paraffinic hydrocarbon compound of the dissolution solvent has a critical pressure of between 2.5 and 5.0 MPa, preferably between 2.7 and 4.6 MPa, preferably between 3.0 and 3.8 MPa, and preferably between 3.0 and 3.5 MPa.
• the dissolution solvent comprises predominantly, preferably at least 80% by weight, preferably at least 95% by weight, preferably 98% by weight, of an aliphatic paraffinic hydrocarbon compound, preferably linear or branched, having a boiling temperature of between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, very preferably between 25 and 61°C and preferably between 25 and 40°C , and containing between 4 and 7 carbon atoms (i.e. C4-C7), preferably 5, 6 or 7 carbon atoms (respectively C5, C6 or C7), preferably containing 5 or 6 atoms of carbon (in C5 or C6) and very preferably containing 5 carbon atoms (in C5).
• an aliphatic paraffinic hydrocarbon compound preferably linear or branched, having a boiling temperature of between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, very preferably between 25 and 61°C and preferably between
• dissolution step a) is carried out at a dissolution temperature of between 120°C and 250°C, preferably between 130 and 225°C, preferably between 150°C and 210°C and preferably between 150°C. and 195°C, and a dissolution pressure of between 1.0 and 25.0 MPa absolute, preferably between 1.0 and 20.0 MPa absolute, preferably between 3.0 and 18.0 MPa absolute, very preferably between 5.0 and 18.0 MPa absolute and preferably between 6.0 and 17.0 MPa absolute.
• the temperature and pressure can vary throughout step a), from the conditions of introduction of the plastic filler and/or the dissolution solvent, for example from ambient conditions, that is to say -say a temperature between 10 and 30°C and atmospheric pressure (0.1 MPa), until reaching the dissolution conditions, that is to say the dissolution temperature, in particular between 120°C and 250 °C, preferably between 130 and 225°C, preferably between 150°C and 210°C and preferably between 150 and 195°C, and the dissolution pressure, in particular between 1.0 and 25.0 MPa abs. , preferably between 1.0 and 20.0 MPa abs., preferably between 3.0 and 18.0 MPa abs., preferably between 5.0 and 18.0 MPa abs. and very preferably between 6.0 and 17.0 MPa abs.
• the flow of dissolved polymer is at the dissolution temperature and at the dissolution pressure.
• the temperature in step a) to a temperature less than or equal to 250°C, preferably less than or equal to 225°C, preferably less than or equal to 210°C or even 195°C, allows avoid or limit the thermal degradation of polymers, in particular thermoplastics and more particularly polyolefins, but also to limit the energy requirement of the process, thus participating in limiting the operating costs and the carbon footprint of the process.
• the dissolution temperature is greater than or equal to the melting temperature of the polymers, in particular thermoplastics and more particularly polyolefins, so as to promote their dissolution.
• the dissolution pressure is advantageously greater than the saturated vapor pressure of the dissolution solvent, at the dissolution temperature, so that the dissolution solvent is at least partly, and preferably entirely, in liquid form. , at the dissolution temperature, so as to optimize the dissolution of the targeted thermoplastics.
• the dissolution temperature and pressure conditions reached in step a) are adjusted so that the mixture (dissolution solvent + targeted thermoplastics) is homogeneous and very preferably monophasic, said mixture possibly comprising insoluble impurities suspended in said mixture.
• the weight ratio (filler/solvent) between the plastic filler and the dissolution solvent is between 0.01 and 2.0, preferably between 0.05 and 1.0, preferably between 0.10 and 0.8.
• dissolution step a) is carried out for a residence time of between 1 and 600 minutes, preferably between 2 and 300 minutes, preferably between 5 and 180 minutes.
• the residence time is understood as the residence time at the dissolution temperature and at the dissolution pressure, that is to say the time of implementation of the plastic filler with the dissolution solvent at the dissolution temperature and at the dissolution pressure, in step a).
• the dissolution solvent comprises, preferably consists of, a make-up of fresh solvent and/or a stream of recycled solvent from a subsequent step of the process, preferably from step c) of solvent-polymer separation .
• step a) advantageously uses at least one dissolution equipment, and possibly at least one device for preparing the load, a mixing device and/or a transport device.
• This equipment and/or devices can be for example a static mixer, an extruder, a pump, a reactor, a co- or counter-current column, or in a combination of lines and equipment.
• Devices for transporting fluids in particular, such as liquids or solids, are well known to those skilled in the art.
• the transport devices may include a pump, an extruder, a vibrating tube, an endless screw, a valve.
• the equipment and/or devices may also include or be associated with heating systems (for example oven, exchanger, tracing, etc.) to achieve the conditions necessary for dissolution.
• Dissolution step a) can be carried out continuously, discontinuously (or in batch mode) or in fed batch mode (or fed-batch).
• the dissolution step a) is at least supplied by the plastic filler, in particular in the form of one or more flows of plastic filler, and by the dissolution solvent, in particular in the form of one or more flows of solvent of dissolution, advantageously by means of one or more transport devices.
• the plastic filler flow(s) may be distinct from the dissolution solvent flow(s).
• Part or all of the plastic filler can also feed step a) mixed with part or all of the dissolution solvent, the remainder of the solvent and/or filler, where appropriate, being able to feed the step a) separately.
• the dissolution solvent is advantageously at least partly, and preferably entirely, in liquid form, while the plastic filler, which comprises thermoplastic polymers in particular polyolefins, can be in solid or liquid form possibly comprising solid particles in suspension.
• the plastic filler can also optionally be injected into the dissolution equipment, mixed with the dissolution solvent, in the form of a suspension in the dissolution solvent, the preparation and injection of the suspension being able to be continuous or discontinuous.
• step a) can use an extruder and possibly at least one other dissolution equipment.
• the plastic filler feeds, possibly with at least a fraction of the dissolution solvent, the extruder so that, at the outlet of the extruder, at least a part and preferably all of the targeted thermoplastic polymers, more particularly polyolefins, included in the charge, are in the molten state (and/or at least partly dissolved).
• the plastic filler optionally mixed with at least a fraction of the dissolution solvent, is then injected into dissolution equipment, for example of the reactor type, at least partly in molten (or partly dissolved) form.
• the plastic filler at least partly in the molten state (or partly dissolved) at the extruder outlet, can also be pumped using a pump dedicated to viscous fluids often called a “melt” pump or pump. geared.
• the plastic filler, at least partly in the molten state (or partly dissolved) can also be, at the extruder outlet, filtered using a filtration device, possibly in addition to the melt pump. ", in order to eliminate the largest particles, generally the mesh size of this filter is between 10 microns and 1 mm, preferably between 20 and 200 microns.
• step a) uses an extruder in which the dissolution solvent is injected, advantageously at several points, so as to promote shearing and therefore intimate mixing between the dissolution solvent and the plastic filler, this which contributes to the dissolution of thermoplastics and more particularly polyolefins.
• the treatment process may comprise an intermediate adsorption step a'), located during the dissolution step a) or directly downstream of the dissolution step a), and which includes the introduction of an adsorbent solid, preferably of the alumina, silica, silica-alumina, activated carbon or bleaching earth type, in the form of divided particles, in the raw polymer solution obtained at the end of step a) or optionally during step a) of dissolution.
• the solid adsorbent can then be eliminated during purification step b), for example during a step b1) of separation of insolubles and/or a washing step b2).
• the raw polymer solution obtained at the end of dissolution step a) comprises at least the dissolution solvent, polymers, in particular the thermoplastic polymers that the present invention seeks to recover purified, dissolved in the dissolution solvent.
• the raw polymer solution also includes soluble impurities also dissolved in the dissolving solvent.
• the raw polymer solution may optionally also comprise impurities or insoluble compounds in suspension.
• the raw polymer solution obtained at the end of step a) may optionally also comprise polymers, other than the targeted polymers, for example in the molten state.
• the targeted thermoplastics, in particular polyolefins, of the plastic filler are advantageously solubilized, in whole or in part, in the dissolution solvent .
• the thermoplastic solution obtained ie the raw polymer solution
• step b) of purification then step c) of solvent-polymer separation, so as to recover the thermoplastics from the plastic filler, in purified form, with very low levels of impurities and residual solvent and compatible with any type of subsequent application.
• thermoplastics in particular polyolefins
• plastic waste in an optimal manner and under completely reasonable operating conditions (in particular a well-bounded dissolution pressure, i.e. say limited), and therefore controlled energy consumption and therefore with limited cost.
• the purification process according to the invention comprises a step of purification of the raw polymer solution resulting from step a).
• This purification step b) comprises at least one of the sub-steps b1), b2), b3), b4) described below: b1) a sub-step of separating insolubles, b2) a sub-step of washing, by contact with a dense solution, b3) an extraction sub-step, by contact with an extraction solvent, b4) a sub-step of adsorption of impurities by contact with an adsorbent.
• the different sub-steps b1), b2), b3) and b4) which can be implemented in purification step b) can be operated continuously, batchwise (or in batch mode) or in fed batch mode ( or fed-batch).
• purification step b) comprises at least one substep b1) of separation of insolubles.
• Purification step b) preferably comprises several (that is to say at least two) sub-steps chosen from sub-steps b1), b2), b3) and b4), in series, and preferably at least one substep b1) of separation of insolubles and for example a substep b4) of adsorption, and very advantageously in this order.
• the combination of at least two sub-steps chosen from b1), b2), b3) and b4) advantageously allows optimal purification of the polymer solution.
• the polymer solution obtained at the end of step b) is a purified polymer solution and comprises the targeted thermoplastics, dissolved in the dissolution solvent.
• This purified polymer solution can correspond to a clarified polymer solution resulting from a sub-step b1) of separation of insolubles, a washed polymer solution resulting from a washing sub-step b2), an extracted polymer solution resulting from a sub-step -step b3) of extraction or a refined polymer solution resulting from a sub-step b4) of adsorption of impurities.
• the purification process may comprise a sub-step b1) of separation of insolubles by solid-liquid separation, to advantageously obtain at least one clarified polymer solution (that is to say devoid of at least one part, preferably of all of the insolubles that the crude polymer solution comprises) and preferably an insoluble fraction.
• the insoluble fraction advantageously comprises, at least in part, preferably all, insoluble impurities, in particular suspended in the raw polymer solution resulting from step a).
• Substep b1) of separation of insolubles thus makes it possible to eliminate at least part, preferably all, of the particles of compounds insoluble in the dissolution solvent, present in suspension in the raw polymer solution resulting from step a ) or a possible step a').
• the insoluble compounds (or impurities) eliminated during substep b1) of separation of insolubles are for example pigments, mineral compounds, packaging residues (glass, wood, cardboard, paper, aluminum) and insoluble polymers. .
• this separation substep b1) advantageously makes it possible, in addition to the elimination of at least part of the insoluble impurities, to limit operational problems, in particular of the blockage and/or erosion type, of the steps of the process located downstream of such a sub-step b1), while contributing to the purification of the plastic filler.
• Substep b1) of separation of insolubles is advantageously carried out at a temperature between 120°C and 250°C, preferably between 130 and 225°C, preferably between 150°C and 210°C and preferably between 150 and 195°C, and a pressure of between 1.0 and 25.0 MPa absolute, preferably between 1.0 and 20.0 MPa absolute, preferably between 3.0 and 18.0 MPa absolute, preferably between 5.0 and 18.0 MPa absolute and very preferably between 6.0 and 17.0 MPa absolute.
• substep b1) of separation of insolubles is carried out at temperature conditions and pressure at the outlet of dissolution step a), that is to say at the dissolution temperature and the dissolution pressure as defined above.
• substep b1) of separation of insolubles is preferably supplied with the raw polymer solution from step a) or from a possible intermediate adsorption step a').
• sub-step b1) can be supplied with a washed polymer solution resulting from a washing sub-step b2).
• substep b1) implements at least one solid-liquid separation section (or solid-liquid-liquid separation, particularly in the case where the effluent obtained at the end of the dissolution step comprises in addition to the polymer solution and solid impurities, impurities and/or polymers of a different nature than the thermoplastic in question, in liquid form and with little or no soluble).
• the solid-liquid separation section comprises at least one piece of solid-liquid separation equipment, for example a separator flask, a decanter, a centrifugal decanter, a centrifuge, a filter, a sand filter, a tangential filter using in particular a membrane and/or a depth filter, an eddy current separator, an electrostatic separator, a triboelectric separator, preferably a decanter, a filter, a sand filter and/or an electrostatic separator.
• a self-cleaning filter can be used, the cleaning or unclogging allowing the elimination of insoluble matter being carried out using a flow of solvent.
• substep b1) implements at least one decantation section advantageously comprising at least one decanter and/or at least one filtration section.
• filtration aids for example diatomaceous earth or sand
• the evacuation of the insoluble fraction can be facilitated by equipment allowing the transport and/or elimination of traces of solvent possibly present in the insoluble fraction, for example a conveyor, a vibrating tube, an endless screw, an extruder, a striping.
• Substep b1) can therefore use equipment for transport and/or elimination of traces of solvent to evacuate the insoluble fraction.
• at least part of the solvent recovered during substep b1) is recycled in the process.
• sub-step b1) of separation of insolubles uses at least two, and generally less than five, solid-liquid separation equipment in series and/or in parallel.
• the presence of at least two solid-liquid separation equipment in series makes it possible to improve the elimination of insoluble matter, while the presence of equipment in parallel makes it possible to manage the maintenance of said equipment and/or unclogging operations.
• Certain insoluble compounds, in particular certain pigments and mineral fillers, conventionally added during the formulation of polymers, can be in the form of particles of less than 1 ⁇ m. This is for example the case of titanium dioxide, calcium carbonate and carbon black.
• sub-step b1) of separating the insolubles advantageously uses an electrostatic separator, which makes it possible to effectively eliminate, at least in part, the insoluble particles of size less than 1 pm.
• sub-step b1) of insolubles uses a sand filter, to eliminate particles of different sizes and in particular particles of size less than 1 pm.
• substep b1) of insolubles uses a tangential filter using in particular a membrane and/or a depth filter, possibly in the presence of filtration aids such as for example earth diatoms.
• the polymer solution which feeds sub-step b1) may optionally also comprise a second liquid phase, for example consisting of molten polymers of a nature different from that of thermoplastics. targeted.
• substep b1) advantageously implements a solid-liquid-liquid separation section, using equipment allowing the separation of two liquid phases and a solid phase, preferably by means of at least one two-phase or three-phase separator.
• the purification process may optionally comprise a sub-step b2) of washing with a dense solution, to advantageously obtain at least one washed polymer solution and preferably a washing effluent.
• the washed polymer solution obtained at the end of sub-step b2) advantageously comprises the targeted thermoplastic polymers that the present invention seeks to recover purified, dissolved in the dissolution solvent.
• the washed polymer solution may still include residual impurities, in particular soluble in the dissolution solvent and/or possibly traces of the washing solvent (i.e. dense solution) if substep b2) is carried out.
• Washing sub-step b2) can be integrated upstream or downstream, preferably downstream, of a sub-step b1) of separation of insolubles, when these two sub-steps are integrated into step b) of purification.
• the washing sub-step b2) is supplied with a dense solution and with the raw polymer solution from step a) or from a possible intermediate adsorption step a'), or by the clarified polymer solution from b1).
• There polymer solution which feeds the washing sub-step b2), in particular the raw or clarified polymer solution, may comprise impurities in the form of insoluble compounds in suspension and/or in the form of solubilized compounds. These suspended or solubilized compounds can, in part or in whole, be eliminated during substep b2) of washing by dissolution or precipitation and/or by entrainment in the dense solution.
• this substep b2) contributes to the treatment of the plastic filler and more particularly to the purification of the polymer solution.
• Washing sub-step b2) advantageously comprises bringing the polymer solution which feeds sub-step b2), that is to say the crude or clarified polymer solution, into contact with a dense solution.
• the dense solution has a higher density than the polymer solution (that is to say the mixture comprising at least the targeted thermoplastic polymers and the dissolution solvent in which the targeted thermoplastic polymers are dissolved).
• the dense solution has a density preferably greater than or equal to 0.85, preferably greater than or equal to 0.9, preferably greater than or equal to 1.0, and preferably less than or equal to 1.5.
• the dense solution may be an aqueous solution, which preferably comprises at least 50% by weight of water, preferably at least 75% by weight of water, very preferably at least 90% by weight of water.
• the pH of the aqueous solution can be adjusted using an acid or a base to promote the dissolution of certain compounds.
• the dense solution may also optionally be a solution comprising, preferably consisting of, an organic solvent with a density advantageously greater than or equal to 0.85, preferably greater than or equal to 0.9, preferably greater than or equal to 1.0, and in which the polymers of the plastic filler remain insoluble under the temperature and pressure conditions of substep b2), for example an organic solvent chosen from sulfolane or N-methylpyrrolidone (NMP), optionally mixed with water.
• the dense solution is an aqueous solution which preferably comprises at least 50% by weight of water, preferably at least 75% by weight of water, very preferably at least 90% by weight of water.
• Washing substep b2) is advantageously carried out at a temperature between 120°C and 250°C, preferably between 130 and 225°C, preferably between 150°C and 210°C and preferably between 150 and 210°C. 195°C, and a pressure of between 1.0 and 25.0 MPa absolute, preferably between 1.0 and 20.0 MPa absolute, preferably between 3.0 and 18.0 MPa absolute, preferably between 5, 0 and 18.0 MPa absolute and very preferably between 6.0 and 17.0 MPa absolute.
• washing substep b2) is carried out at the dissolution temperature and the dissolution pressure.
• the mass ratio (dense solution / polymer solution) between the mass flow rate of the dense solution and the flow rate mass of the polymer solution which feeds substep b2) is advantageously between 0.05 and 20.0, preferably between 0.1 and 10.0 and preferably between 0.5 and 3.0.
• the contact between the polymer solution and the dense solution can be carried out at several points of the equipment(s) used, that is to say by several injections of the polymer solution and/or the dense solution at different points along the equipment(s), it is then the sum of the injected flows which is taken into account in the calculation of the mass ratio (dense solution / polymer solution).
• Substep b2) can be carried out in one or more washing equipment allowing contact with the dense solution and/or with separation equipment making it possible to recover at least one washing effluent and a washed polymer solution.
• This equipment is well known, for example stirred reactors, static mixers, decanter mixers, two-phase or three-phase separator flasks, co- or counter-current washing columns, plate columns, stirred columns, packed columns, pulsed columns, etc., each type of equipment may include one or more equipment used alone or in combination with equipment of another type.
• the washing sub-step b2) is carried out in a counter-current washing column in which the dense solution is injected, preferably in the upper half, preferably the third, of the column. preferably closest to the column head, on the one hand and the crude or clarified polymer solution is injected, preferably in the lower half, preferably the third, of the column preferably closest to the column bottom , on the other hand.
• the dense solution is injected, preferably in the upper half, preferably the third, of the column. preferably closest to the column head, on the one hand and the crude or clarified polymer solution is injected, preferably in the lower half, preferably the third, of the column preferably closest to the column bottom , on the other hand.
• the flows entering and/or leaving the washing column can be divided and injected into several injection points along the column and/or drawn off at several withdrawal points along the column.
• washing sub-step b2) is carried out in a mixer-settler comprising an agitated mixing zone, to bring the dense solution and the raw or clarified polymer solution into contact, and a decantation zone, making it possible to recover a washed polymer solution and advantageously a washing effluent.
• the washing effluent advantageously obtained comprises in particular compounds solubilized in the dense solution and/or insoluble and entrained in the washing effluent.
• the washing effluent can be reprocessed in a washing effluent treatment section, on the one hand to separate at least in part the compounds solubilized and/or entrained and optionally purify the washing effluent, to obtain a purified dense solution, and on the other hand to recycle at least part of the purified dense solution.
• This washing effluent treatment section can use one or more well-known solid-liquid separation equipment(s), for example a separator flask, a decanter, a centrifugal decanter, a centrifuge, a filter. .
• the washing effluent can also be sent outside the process, for example to a wastewater treatment plant when the dense solution is an aqueous solution.
• Step b) of the process according to the invention may comprise a sub-step b3) of extraction by bringing into contact with an extraction solvent, to obtain at least one extracted polymer solution and preferably a used solvent in particular charged in impurities.
• the extracted polymer solution obtained at the end of substep b3) advantageously comprises the targeted thermoplastic polymers that the present invention seeks to recover purified, dissolved in the dissolution solvent.
• the extracted polymer solution may also include residual impurities, in particular soluble in the dissolution solvent and/or traces of dense solution and/or the extraction solvent if the sub-step(s) ⁇ ) b2) and/or b3) is(are) carried out.
• substep b3) of extraction is advantageously located between step a) of dissolution and step c) of solvent-polymer separation, preferably downstream of a sub-step b1) of separation of insolubles and possibly upstream or downstream of a sub-step b4) of adsorption if the latter is also integrated into step b).
• the extraction substep b3) is advantageously supplied with an extraction solvent and with the polymer solution, in particular the raw polymer solution resulting from step a), the clarified polymer solution resulting from substep b1) , the washed polymer solution from sub-step b2) or the refined polymer solution from an adsorption sub-step b4).
• extraction substep b3) is supplied with an extraction solvent and with the clarified polymer solution from substep b1) or the washed polymer solution from substep b2), or else possibly by a refined polymer solution resulting from an adsorption substep b4).
• the polymer solution which feeds substep b3) preferably the clarified polymer solution, the washed polymer solution or the refined polymer solution, can therefore optionally comprise solubilized compounds or solubilized impurities. These solubilized compounds can then be partially or entirely eliminated during extraction substep b3) by bringing them into contact with an extraction solvent.
• the combination of an extraction sub-step b3) with a sub-step b1) separation of insolubles and optionally a washing sub-step b2) and/or an adsorption sub-step b4) allows improved purification of the polymer solution, using both the affinity of the impurities for the solvent of extraction and possibly for the dense solution and/or the adsorbent.
• the extraction substep b3) advantageously implements at least one extraction section, preferably between one and five extraction section(s), in a very preferred an extraction section.
• the mass ratio (extraction solvent/polymer solution) between the mass flow rate of the extraction solvent and the mass flow rate of the polymer solution feeding b3), preferably the clarified polymer solution, the washed polymer solution or the refined polymer solution is advantageously between 0.05 and 20.0, preferably between 0.1 and 10.0 and preferably between 0.2 and 5.0.
• the bringing into contact between the polymer solution which feeds sub-step b3), preferably the clarified polymer solution, the washed polymer solution or the refined polymer solution, and the extraction solvent can be carried out at several points of section d extraction, that is to say by several injections of the polymer solution and/or the extraction solvent at different points along the extraction section, it is then the sum of the injected flows which is taken into account account in the calculation of the mass ratio (extraction solvent / polymer solution).
• the extraction solvent used in extraction substep b3) advantageously comprises an organic solvent or a mixture of organic solvents.
• the extraction solvent comprises, preferably consists of, at least one advantageously aliphatic, preferably paraffinic, hydrocarbon compound, preferably at least one alkane, having a boiling point of between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, preferably between 25 and 61°C and very preferably between 25 and 40°C.
• the extraction solvent mainly comprises, preferably at least 80% by weight, preferably at least 95% by weight, preferably 98% by weight of a hydrocarbon compound, preferably aliphatic paraffinic (or alkane) (100% being the maximum, the percentages being expressed relative to the total weight of the solvent dissolution), having a boiling point between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, preferably between 25 and 61°C and very preferably between 25 and 40°C.
• a hydrocarbon compound preferably at least 80% by weight, preferably at least 95% by weight, preferably 98% by weight of a hydrocarbon compound, preferably aliphatic paraffinic (or alkane) (100% being the maximum, the percentages being expressed relative to the total weight of the solvent dissolution)
• a hydrocarbon compound preferably between 8 and 100°C, preferably between 25 and 69°C, preferably between 25 and 61°C and very preferably between 25 and 40°C.
• the advantageously aliphatic, preferably paraffinic hydrocarbon compound, the majority of the extraction solvent has a critical temperature (temperature at the critical point of said pure hydrocarbon compound) of between 130 and 285°C, preferably between 158 and 285°C, preferably between 185 and 245°C, preferably between 185 and 230°C and very preferably between 185 and 200°C.
• the extraction solvent comprises predominantly, preferably at least 80% by weight, preferably at least 95% by weight, preferably 98% by weight of an aliphatic paraffinic hydrocarbon compound, preferably linear or branched, having a boiling temperature of between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, preferably between 25 and 61°C and very preferably between 25 and 40 °C, and containing between 4 and 7 carbon atoms (from C4 to C7), preferably 5, 6 or 7 carbon atoms (respectively in C5, C6 or C7), preferably containing 5 or 6 carbon atoms (in C5 or C6) and preferably containing 5 carbon atoms (in C5).
• an aliphatic paraffinic hydrocarbon compound preferably linear or branched, having a boiling temperature of between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, preferably between 25 and 61°C and very preferably between 25 and 40 °C
• the extraction solvent used in b3) is the same solvent as the dissolution solvent used in step a), possibly in a different physical state (for example the extraction solvent with supercritical state relative to the dissolution solvent in the liquid state), so as to facilitate the management of the solvents and in particular their purification and their recycling in particular towards the dissolution step a) and possibly towards the sub-step b3) d 'extraction.
• Another advantage of using identical dissolution and extraction solvents, in identical or different physical states lies, in addition to facilitating the management of the solvents involved in the process according to the invention, in particular the recovery of the solvents, their treatment and their recycling towards at least one of the stages of the process, in limiting energy consumption and costs in particular generated by the treatment and purification of solvents.
• the extraction section(s) of b3) may include extraction equipment(s), allowing contact with the extraction solvent and/or with separation equipment making it possible to recover at least one used solvent, in particular loaded with impurities, and an extracted polymer solution.
• This equipment is well known, such as stirred reactors, static mixers, decanter mixers, two-phase or three-phase separator flasks, co- or counter-current washing columns, plate columns, stirred columns, packed columns, pulsed columns, etc.
• each type of equipment may include one or more equipment used alone or in combination with equipment of another type.
• the extraction is carried out in a counter-current extraction column where the extraction solvent is injected on the one hand and the polymer solution which feeds sub-step b3) is injected on the other hand.
• the extraction solvent is injected on the one hand and the polymer solution which feeds sub-step b3) is injected on the other hand.
• the polymer solution which feeds b3) preferably the clarified, washed or refined polymer solution
• the polymer solution which feeds b3) is injected into the upper half, preferably the third, of the column, preferably the closest from the head of the counter-current extraction column, while the extraction solvent is injected into the lower half, preferably the third, of the column, preferably closest to the bottom of the extraction column against a current.
• the flows entering and/or leaving the counter-current extraction column can be divided into several injection and/or withdrawal points along the column.
• the extraction is carried out in a mixer-decanter which advantageously comprises an agitated mixing zone to, on the one hand, bring the extraction solvent into contact with the polymer solution which supplies b3 ), preferably the clarified, washed or refined polymer solution, and on the other hand a decantation zone making it possible to recover an extracted polymer solution on the one hand and a used solvent on the other hand.
• a mixer-decanter which advantageously comprises an agitated mixing zone to, on the one hand, bring the extraction solvent into contact with the polymer solution which supplies b3 ), preferably the clarified, washed or refined polymer solution, and on the other hand a decantation zone making it possible to recover an extracted polymer solution on the one hand and a used solvent on the other hand.
• extraction substep b3) is carried out under temperature and pressure conditions different from the temperature and pressure conditions of dissolution step a).
• the extraction substep b3) implements a liquid/liquid extraction section.
• the liquid/liquid extraction section is operated between 120°C and 250°C, preferably between 130 and 225°C, preferably between 150°C and 210°C and preferably between 150 and 195°C.
• the temperature and pressure conditions are adjusted so that the extraction solvent is in the liquid state, the dissolution solvent preferably also being in the liquid state.
• the liquid/liquid extraction in particular when the extraction solvent is the same as the dissolution solvent, is carried out under temperature and pressure conditions different from the dissolution conditions of step a), in particular at a temperature higher than the dissolution temperature and/or at a pressure lower than the dissolution pressure, so as to thus be placed in a two-phase zone of the corresponding polymer-solvent mixture diagram.
• the extraction substep b3) implements an extraction section under particular temperature and pressure conditions in which the extraction solvent is advantageously, at least in part , in supercritical form.
• Such extraction may be called supercritical extraction.
• the extraction is carried out by bringing the polymer solution which feeds b3), preferably the clarified, washed or refined polymer solution, into contact with a solvent extraction, advantageously under temperature and pressure conditions which make it possible to obtain a supercritical phase composed mainly (that is to say preferably at least 50% by weight, preferably at least 70% by weight, so preferred at least 90% by weight) of the extraction solvent.
• the extraction is carried out by bringing the polymer solution which feeds b3), preferably the clarified, washed or refined polymer solution, into contact with an extraction solvent which is at less in part, preferably in full, in the supercritical state.
• an extraction solvent which is at less in part, preferably in full, in the supercritical state.
• the use of an extraction solvent in the supercritical state also makes it possible to create a significant density difference between the supercritical phase and the polymer solution in liquid form, which facilitates demixing and separation by decantation between the two phases. , or between the supercritical phase and the liquid phase, which consequently contributes to the efficiency of the purification of the polymer solution.
• substep b3) uses an extraction solvent comprising predominantly, preferably at least 80% by weight, preferably at least 95% by weight, preferably 98% by weight of a compound hydrocarbon, preferably aliphatic paraffinic (or alkane), (100% being the maximum, the percentages being expressed relative to the total weight of the dissolution solvent), having a critical temperature preferably between 130 and 285°C, preferably between 158 and 285°C, preferably between 185 and 245°C, preferably between 185 and 230°C and very preferably between 185 and 200°C.
• a critical temperature preferably between 130 and 285°C, preferably between 158 and 285°C, preferably between 185 and 245°C, preferably between 185 and 230°C and very preferably between 185 and 200°C.
• the extraction solvent mainly comprises, preferably at least 80% by weight, preferably at least 95% by weight, preferably 98% by weight of a aliphatic paraffinic hydrocarbon compound having a boiling temperature of between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, very preferably between 25 and 61°C and preferably between 25 and 40°C, and containing between 4 and 7 carbon atoms (i.e.
• the majority paraffinic aliphatic hydrocarbon compound of the extraction solvent has a critical pressure of between 2.5 and 5.0 MPa, preferably between 2.7 and 4.6 MPa, preferably between 3.0 and 3. .8 MPa, and preferably between 3.0 and 3.5 MPa.
• substep b3) of supercritical extraction of this particular embodiment is carried out at a temperature preferably between 160°C and 300°C, preferably between 190 and 250°C, preferably between 200°C.
• the pressure at which the supercritical extraction is carried out is very advantageously between the critical pressure (PC (solvent extraction)) of the majority paraffinic aliphatic hydrocarbon compound of the extraction solvent (that is to say, preferably, the critical pressure of the majority paraffinic aliphatic hydrocarbon compound having a boiling temperature of between -15 and 100°C, preferably between 8 and 100°C , preferably between 25 and 69°C, very preferably between 25 and 61°C and preferably between 25 and 40°C, and containing between 4 and 7 carbon atoms, preferably 5, 6 or 7 carbon atoms, preferably containing 5 or 6 carbon atoms and very preferably containing 5 carbon atoms, as defined above) and
• the temperature and pressure conditions are adjusted, in particular in an adjustment section implemented in substep b3) of extraction upstream of the extraction section, of so that the extraction solvent is at least partly in the supercritical state in the extraction section, the adjustment of the temperature and pressure of the extraction solvent in said adjustment section being advantageously carried out by known means of those skilled in the art (by implementing for example pump and/or valve and/or turbine and/or exchanger and/or oven).
• the extraction substep b3) implements a supercritical extraction and the extraction solvent is the same as the dissolution solvent (or comprises the same majority compound as the dissolution solvent and possibly impurities), apart from the fact that the extraction solvent is at least partly in the supercritical phase.
• the used solvent obtained is in particular loaded with impurities. It can be reprocessed in an organic treatment section making it possible on the one hand to separate at least part of the impurities and purify the solvent to obtain a purified extraction solvent, and on the other hand to recycle at least part of the solvent.
• the used solvent can be treated according to any method known to those skilled in the art, such as for example one or more of the following methods: distillation, evaporation, extraction, adsorption, crystallization and precipitation of insolubles, or by purging.
• Step b) of the treatment process according to the invention may comprise an adsorption sub-step b4), to obtain at least one refined polymer solution.
• the refined polymer solution obtained at the end of substep b4) advantageously comprises the targeted thermoplastic polymers that the present invention seeks to recover purified, dissolved in the dissolution solvent.
• substep b4) of adsorption is advantageously carried out downstream of step a) of dissolution and upstream of step c) of solvent-polymer separation .
• It can be implemented upstream of a sub-step b1) of separation of insolubles and/or b2) of washing and correspond in particular to the possible step a') of intermediate adsorption.
• it is implemented downstream of a sub-step b1) of separation of insolubles and possibly of a sub-step b2) of washing itself preferably downstream of sub-step b1).
• It can also be implemented, for example, upstream or downstream of an extraction sub-step b3).
• substep b4) of adsorption is implemented by bringing into contact the polymer solution which feeds it, in particular the raw polymer solution resulting from step a), the clarified polymer solution resulting from b1) or washed from b2) or the extracted polymer solution from b3), with one (or more) adsorbent(s).
• the adsorption substep b4) advantageously uses an adsorption section operated in the presence of at least one adsorbent, preferably solid, and in particular in the form of a fixed bed, an entrained bed (or slurry, i.e. that is to say in the form of particles introduced into the flow to be purified and entrained with this flow) or in the form of a bubbling bed, preferably in the form of a fixed bed or entrained bed.
• sub-step b4) of fixed bed adsorption of adsorbent(s) is preferably implemented downstream of a separation sub-step b1) insolubles and/or a washing sub-step b2), and possibly upstream or downstream of an extraction sub-step b3).
• a sub-step b1) of separation of insolubles and/or a sub-step b2) of washing, and possibly of a sub-step b3) of extraction, with a sub-step b4 ) adsorption allows improved purification of the polymer solution, using both the affinity of the residual impurities for the adsorbent and for the extraction solvent and possibly a dense solution.
• the process comprises a step c) of solvent-polymer separation, to obtain at least one fraction of purified thermoplastic polymers, more particularly at least one fraction of purified polyolefins and preferably a solvent fraction.
• Solvent-polymer separation step c) advantageously uses at least one supercritical separation section, followed by at least one solvent recovery section, preferably between one and five solvent recovery section(s), in series. .
• the solvent-polymer separation step c), more particularly the supercritical separation section, in particular the first supercritical separation section, is supplied with the purified polymer solution resulting from the purification step b).
• Step c) of solvent-polymer separation thus aims firstly to separate at least in part, preferably mainly, or even entirely, the solvent(s), in particular the dissolution solvent, contained(es). in the purified polymer solution which feeds step c), so as to recover the thermoplastic polymers removed at least in part, preferably predominantly and preferably entirely, impurities and the dissolution solvent and possibly the other solvent(s) used in the process (that is to say the extraction solvent and/or the dense solution).
• Solvent-polymer separation step c) also aims to recover at least in part, preferably mainly and preferably in totality, the solvent(s) contained in the purified polymer solution which feeds step c ), in particular the dissolution solvent and possibly the extraction solvent and/or the dense solution.
• the solvent(s) contained in the purified polymer solution which feeds step c ) in particular the dissolution solvent and possibly the extraction solvent and/or the dense solution.
• step c) advantageously also makes it possible to obtain at least one solvent fraction.
• the solvent-polymer separation step c) also optionally aims to purify the recovered solvent fraction and recycle it in particular upstream of the dissolution step a) and possibly upstream of the washing and/or sub-step b2). or sub-step b3) of extraction.
• Step c) of solvent-polymer separation thus implements a supercritical separation section which makes it possible to separate at least a part of the dissolution solvent, possibly of the extraction solvent and/or of the dense solution, and optionally a part residual impurities which would not have been eliminated during step b), under temperature and pressure conditions adjusted so as to be placed in supercritical conditions, that is to say beyond the critical point of the solvent(s) to be separated, in particular beyond the critical point of the dissolution solvent, more particularly beyond the critical point of the majority hydrocarbon compound of the dissolution solvent, which advantageously allows easy separation and recovery at least part of the solvent, in particular the dissolving solvent.
• This supercritical separation section in particular uses a fluid system which consists of a supercritical phase comprising mainly solvent, in particular dissolution solvent, and a liquid phase comprising thermoplastic polymers.
• the term "mainly” means here, at least 50% by weight, preferably at least 70% by weight, preferably at least 90% by weight, very preferably at least 95% by weight, relative to the weight of the flow considered, c that is to say the supercritical phase.
• the separation can then be called supercritical separation of the solvent(s).
• the supercritical separation of the solvent(s) makes it possible to effectively separate on the one hand at least part of the solvent(s) and in particular the dissolution solvent and on the other hand the thermoplastic polymers or a polymer solution concentrated, the supercritical separation being advantageously enabled by the significant difference in density between the two phases, the supercritical phase and the liquid phase comprising the thermoplastic polymers.
• the supercritical separation of the solvent(s) advantageously makes it possible to present a significantly reduced energy and environmental cost compared to a simple vaporization of the solvent, since during the transition to the supercritical state, there is no of latent heat of vaporization.
• the supercritical separation section is advantageously operated at a temperature between 160°C and 300°C, preferably between 190 and 250°C, preferably between 200°C and 230°C, and at a pressure (Psupercritical) between 2 .7 and 10.0 MPa absolute, preferably between 3.0 and 6.0 MPa absolute, preferably between 3.0 and 5.0 MPa absolute and preferably between 3.0 and 4.0 MPa absolute.
• the supercritical separation section is implemented at a pressure (Psupercritical) between the critical pressure of the majority hydrocarbon compound of the dissolution solvent (PC (dissolution solvent)) and a pressure equal to 3.0 MPa beyond the critical pressure of the majority hydrocarbon compound of the dissolution solvent (i.e.: PC(dissolution solvent) + 3.0 MPa), preferably between the critical pressure of the majority hydrocarbon compound of the dissolution solvent (PC (solvent dissolution)) and a pressure equal to 1.5 MPa beyond the critical pressure of the majority hydrocarbon compound of the dissolution solvent (that is to say: PC (solvent dissolution) + 1.5 MPa ), preferably between the critical pressure of the compound majority hydrocarbon compound of the dissolution solvent (PC(solvent)) and a pressure equal to 0.5 MPa beyond the critical pressure of the majority hydrocarbon compound of the dissolution solvent (that is to say: equal to PC(solvent) dissolution) + 0.5 MPa), the pressures being absolute pressures, the majority hydrocarbon compound of the dissolution solvent being an advantageously
• the supercritical separation section of step c) is preferably carried out by demixing then decanting the liquid phase (comprising the thermoplastic polymers) and the supercritical phase (composed of solvent).
• the supercritical phase resulting from the supercritical separation section constitutes at least in part the solvent fraction obtained at the end of step c).
• the liquid phase which includes the thermoplastic polymers is preferably sent to a solvent recovery section or a series of solvent recovery sections.
• Step c) may optionally comprise one or more successive supercritical separation sections, in particular between one and five, more particularly one, two or three.
• the liquid phase which comprises polypropylene and which comes from a supercritical separation section can therefore also be supplied to another subsequent supercritical separation section, the liquid phase of the last supercritical separation section being advantageously sent to a solvent recovery section or a series of solvent recovery sections.
• step c) comprises a supercritical separation section.
• the supercritical separation of the solvent makes it possible to further reduce the content of residual impurities in the fraction of purified thermoplastic polymers, more particularly at least one fraction of purified polyolefins.
• Each solvent recovery section is implemented at a temperature advantageously operated at a temperature between 160 and 300°C (and preferably at a temperature higher than the melting temperature of the targeted thermoplastic polymers) and a pressure between the pressure implemented in the supercritical separation section (Psupercritical) and 0.000005 MPa (i.e. 5 Pa).
• each solvent recovery section is carried out at a temperature between 160 and 300°C and at a pressure between the pressure of the previous section of step c) and 0.000005 MPa.
• step c) implements a supercritical separation section and several (at least two) solvent recovery sections, the first solvent recovery section S1, which directly follows the supercritical separation section, is implemented.
• the second solvent recovery section S2 which directly follows the solvent recovery section S1, is operated at a pressure P(S2) between the pressure P(S1) implemented in the first solvent recovery section S1 and 0.000005 MPa, and so on for the following sections.
• the solvent fraction recovered at the end of step c) can be treated in an organic treatment section located at the end of step c), so as to purify it and obtain at least one purified solvent. , in particular at least one purified dissolution solvent, to be able to advantageously recycle it towards the dissolution step a), and possibly towards the washing sub-step b2) or the extraction sub-step b3).
• Said possible organic treatment section at the end of step c) can implement any method known to those skilled in the art, such as for example one or more methods among distillation, evaporation, liquid-liquid extraction, adsorption, crystallization and precipitation of insolubles, or by purging.
• the process according to the invention thus makes it possible to obtain a purified stream of thermoplastic polymers and more particularly polyolefins, from plastic waste, which can be used in any application, for example to replace the same polymers in the virgin state.
• the purified stream of thermoplastics, that is to say the fraction of purified thermoplastic polymers, obtained by the process according to the invention thus has sufficiently low impurity and residual solvent contents to be able to be used in any application.
• the flow of purified thermoplastic polymers, and in particular the flow of purified polyolefins, obtained at the end of the process according to the invention advantageously comprises less than 5% by weight of impurities, very advantageously less than 1% by weight of impurities and very advantageously less than 5% by weight of residual solvent (in particular dissolution solvent), preferably less than 1% by weight of solvent residual, preferably less than 0.1% by weight of residual solvent.
• residual solvent in particular dissolution solvent
• the process for purifying the plastic filler comprises, preferably consists of: a) a dissolution step in a dissolution solvent comprising at least one paraffinic aliphatic hydrocarbon compound, having a temperature of boiling between -15 and 100°C, preferably between 8 and 100°C, preferably between 25 and 69°C, preferably between 25 and 61°C and very preferably between 25 and 40°C, setting implemented at a dissolution temperature of between 120°C and 250°C, preferably between 130 and 225°C, preferably between 150°C and 210°C, preferably between 150 and 195°C, and a pressure of dissolution between 1.0 and 25.0 MPa abs., preferably between 1.0 and 20.0 MPa abs., preferably between 3.0 and 18.0 MPa abs., preferably between 5.0 and 18 .0 MPa abs., and very preferably between 6.0 and 17.0 MPa abs., to obtain at least one crude polymer solution; then b) a dissolution step in a dissolution solvent
• thermoplastic polymers preferably between 3.0 and 4.0 MPa abs, followed by at least one solvent recovery section, operated at a temperature between 160 and 300°C and a pressure between the pressure of the supercritical separation section (Psupercritical) and 0.000005 MPa (i.e. 5 Pa), to obtain at least a fraction of purified thermoplastic polymers.
• Psupercritical supercritical separation section
• 0.000005 MPa i.e. 5 Pa
• the present invention relates to a device for purifying the plastic filler, said device comprising, preferably consisting of: a) a section for dissolving the plastic filler in a dissolution solvent advantageously comprising at least one compound aliphatic paraffinic hydrocarbon, implementation works at a dissolution temperature of between 120°C and 250°C, preferably between 130 and 225°C, preferably between 150°C and 210°C, preferably between 150 and 195°C, and a dissolution pressure between 1.0 and 25.0 MPa abs., preferably between 1.0 and 20.0 MPa abs., preferably between 3.0 and 18.0 MPa abs., preferably between 5.0 and 18, 0 MPa abs., and very preferably between 6.0 and 17.0 MPa abs., to obtain at least one crude polymer solution; then b) a section for purifying the raw polymer solution, comprising: b1) a subsection for separating insolubles; and/or b2) a washing subsection, by contact with
• thermoplastic polymers preferably between 3.0 and 4.0 MPa abs, followed by at least one solvent recovery section, operated at a temperature between 160 and 300°C and a pressure between the pressure of the supercritical separation section Psupercritical and 0.000005 MPa (i.e. 5 Pa), to obtain at least a fraction of purified thermoplastic polymers.
• purification section b) comprises: b1) a subsection for separating insolubles to obtain a clarified polymer solution and an insoluble fraction; then b4) a subsection for adsorption of impurities by contact of the clarified polymer solution with an adsorbent, to obtain at least one refined polymer solution.
• Step a) of dissolution A colored plastic filler in the form of pellets of size less than 5 mm based on polyolefins (containing 95% by weight of a mixture of polypropylene and polyethylene 50/50), resulting from plastic waste, is introduced in the form of flakes into a extruder heated to 180°C. At the exit of the extruder, the charge is at least partly in molten form and is mixed with a solvent comprising 99% n-pentane and previously heated to 180°C, according to a solvent/charge mass ratio of 9/1. The mixture of solvent and filler is introduced into a stirred reactor and heated to 180° C., and maintained at 12 MPa absolute, for a residence time of 1 hour. A polymer solution is then obtained.
• the polymer solution resulting from dissolution step a) is then subjected to purification step b):
• the clarified polymer solution passes through an adsorption section comprising a bed of activated carbon particles with a contact time of 2 hours then a filter allowing the activated carbon particles to be retained.
• This adsorption section is operated at 180°C. It leads to a pressure loss of 0.2 MPa.
• the purified polymer solution resulting from purification step b) is then subjected to a solvent-polymer separation step c) comprising a supercritical section:
• the purified polymer solution from the adsorption section is then heated to 210°C, the pressure being slightly lower than 12 MPa (dissolution pressure minus the pressure losses induced in the sections of step b) of purification).
• the polymer solution is then expanded to 4 MPa absolute then injected into a decanter maintained at 4 MPa abs and 210°C and for a residence time of 5 minutes.
• Two phases are formed: an upper phase comprising mainly n-pentane solvent in the supercritical state and a lower liquid phase comprising polyolefins dissolved in n-pentane solvent.
• the upper phase is withdrawn from the upper part of the decanter.
• the lower liquid phase is then subjected to evaporation of the residual solvent in two successive evaporation sections: firstly at a temperature of 210°C and a pressure of 0.5 MPa for 5 minutes, then secondly at a temperature of 210°C and a pressure of 0.01 MPa for 2 minutes.
• the purified polymer solution resulting from purification step b) is subjected to a solvent-polymer separation step not including a supercritical section:
• the purified polymer solution from the adsorption section is maintained at 180°C and expanded to 2 MPa absolute then injected into a decanter maintained at 2 MPa abs and 180°C, for a residence time of 5 minutes.
• Two phases are formed: an upper gaseous phase composed of n-pentane solvent and a lower liquid phase comprising the polyolefins dissolved in n-pentane solvent.
• the gas phase is withdrawn from the upper part of the decanter.
• the lower liquid phase is then subjected to evaporation of the residual solvent, firstly at a temperature of 210°C and a pressure of 0.5 MPa for 5 minutes, then secondly at a temperature of 210°C and a pressure of 0.01 MPa for 2 minutes.
• Solid B composed of purified polyolefins (polypropylene and polyethylene 50/50) is obtained. Solid B is analyzed.
• the solid B obtained is almost colorless and almost translucent and includes less than 5% by weight of impurities and less than 1% by weight of n-pentane.
• the content of impurities (organic compounds excluding dissolution solvent) of solid B is higher than that measured in solid A obtained in Example 1 in accordance with the invention.
• the energy consumption necessary for the polymer-solvent separation is greater than the energy consumption necessary for the polymer-solvent separation of the process described in Example 1, that is to say when separation polymer-solvent includes a supercritical phase section.

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