EP4034592A2

EP4034592A2 - Process for joint recycling of composite items based on a thermoplastic polymer matrix

Info

Publication number: EP4034592A2
Application number: EP20792469.7A
Authority: EP
Inventors: Jean-Luc Dubois
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2019-09-26
Filing date: 2020-09-25
Publication date: 2022-08-03
Also published as: KR20220068995A; FR3101351B1; US20220324140A1; JP2022549715A; CN114402015B; MX2022003198A; BR112022003483A2; CN114402015A; WO2021058923A2; WO2021058923A3; FR3101351A1

Abstract

The invention relates to a process for recycling (100) a first item (10) to be recycled, comprising a composite material based on a fibrous reinforcement and on a thermoplastic, preferably (meth)acrylic, polymer matrix, characterized in that said recycling process comprises the following steps: - introducing (130) the first item (10) into a system (1) suitable for the recycling of a thermoplastic polymer, - introducing (140), into the system (1) suitable for the recycling of a thermoplastic polymer, a second item (20) to be recycled, comprising a thermoplastic polymer resin, and not comprising a fibrous reinforcement, - heating (150) the items (10, 20) to be recycled at a given temperature, in said system (1) suitable for the recycling of a thermoplastic polymer, in order to depolymerize the thermoplastic, preferably (meth)acrylic, polymers, and to form base monomers of said thermoplastic polymers, and - recovering (160) the constituent base monomers of said thermoplastic polymers.

Description

Joint recycling process for composite articles based on a thermoplastic polymer matrix

[Technical area]

The present invention relates generally to the recycling of articles made of composite material based on a thermoplastic polymer matrix and in particular a method of recycling articles made of composite material based on fibrous reinforcement and on a thermoplastic polymer matrix, such as in particular a thermoplastic (meth) acrylic polymer. The invention further relates to a system for recycling articles of composite material capable of implementing such a method.

The invention is useful in all sectors of industry faced with the problems of recycling composite waste with a thermoplastic polymer matrix, in particular with a thermoplastic (meth) acrylic polymer matrix, post-consumer such as end-of-life products, or industrial waste such as defective products or offcuts from plastics processing operations.

[Prior art]

[003] Composite materials are widely used in various industrial sectors: transport (automobile, rail), sports and leisure, health, wind power, boating or even aeronautics. These composite materials (also called “composites” for short) are a macroscopic combination of at least two materials which are immiscible with one another. Generally, the composite material consists of a polymer matrix which forms a continuous phase on the one hand, and of a reinforcing material (or reinforcement) which is generally a fibrous reinforcement on the other hand. There are also composites consisting of a polymer matrix and mineral filler, for example quartz, marble, silica, aluminum hydroxide, titanium dioxide. Optionally, the composite material also includes additives. These materials are also often associated with other elements such as metal inserts, wood or foams in order to manufacture articles intended for various industries. Their recycling is a major issue in a context of transition towards a circular economy for an efficient use of resources and a reduction of the environmental impacts of products throughout their life cycle. [004] The recycling of articles comprising a composite based on a polymer matrix or polymer composite can be carried out according to several methods. These methods generally involve the thermal degradation of the polymer, that is to say that an increase in the temperature of the polymer causes the loss of the mechanical and physical properties of the polymer followed by its depolymerization.

Pyrolysis is known which is a thermal process consisting of placing the article to be treated in a suitable enclosure and then heating the enclosure so that the heat is transferred to the article. The pyrolysis temperature is generally between 400 and 1300 ° C. in order to allow the chemical decomposition of the polymer matrix. Pyrolysis of the article leads to the formation of gas, an oily residue and a solid residue comprising the reinforcement of the composite, inorganic fillers and a carbonaceous solid. The gases obtained after pyrolysis can be upgraded in the manufacture of new polymer articles, and the solid residue obtained after pyrolysis is in particular upgraded in the manufacture of other products such as insulation materials. This recycling method generally exhibits a poor yield of monomer (e.g. methyl methacrylate). Indeed, it is well known from the literature that composite materials lead, during pyrolysis, to the formation of more residues and to poorer monomer yields than the pure polymer.

[006] Fluidized bed processes are also known in which the fluidized bed can be a bed of silica sand, for example. In this process, the article comprising a composite is generally pre-ground and is placed in a fluidized bed reactor containing the fluidized bed. Fluidization is carried out using a gas flow heated to a temperature generally greater than 400 ° C. In this bed, the matrix is rapidly heated and gasified, thus removing the reinforcement from the matrix. Part of the reinforcement is then carried out of the bed in the gas flow to a secondary combustion chamber. Another part is entrained with the solid constituting the fluidized bed, and taken to a capacity where the solid is reheated, and the carbonaceous residues burnt before being returned to the fluidized bed reactor. As with pyrolysis, this method is not designed to optimize monomer yield.

In particular, poly (methyl methacrylate) (RMMD) is a well established thermoplastic polymer known for its optical properties. Marketed, for example under the name Altuglas®, around 300,000 tonnes of PMMA are produced in Europe each year. Although PMMA can be converted to monomer by thermal depolymerization, only around 30,000 tonnes of PMMA waste is collected for recycling each year in Europe. In addition, to a large extent, the recycling of PMMA in Europe is currently based on a lead process (bed of molten lead) which does not allow the inferior qualities of PMMA to be reprocessed (eg in the form of composites or highly additives) because these inferior qualities lead to the formation of a high quantity of residues and to low yields of monomers.

It appears that the known methods of recycling articles comprising a composite material involve various heating steps which do not allow, in particular in the presence of a fibrous composite, formation of monomers at high yields. [009] Therefore, from an energy and environmental point of view, it is desirable to be able to have a recycling method allowing an improvement in the monomer formation yield during the recycling of fibrous composites based on a thermoplastic polymer matrix. , for example (meth) acrylic.

[Technical problem]

[010] The aim of the invention is to remedy the drawbacks of the prior art. The invention aims in particular to provide a simple and effective solution for depolymerizing a constituent polymer of an article made of composite material based on fibrous reinforcement.

[Brief description of the invention]

[011] To this end, the invention relates to a method for recycling a first article to be recycled comprising a composite material to be recycled. fiber reinforcement base and a thermoplastic polymer matrix, preferably (meth) acrylic, characterized in that said recycling process comprises the following steps:

- introduction of the first article to be recycled into a system suitable for recycling thermoplastic polymer,

- introduction, into the system suitable for recycling thermoplastic polymer, of a second article to be recycled comprising a thermoplastic polymer resin, preferably (meth) acrylic, and not comprising any fibrous reinforcement,

- Heating of the articles to be recycled to a given temperature, in said system suitable for recycling thermoplastic polymer, in order to depolymerize the thermoplastic polymers, preferably (meth) acrylic, and form base monomers of said thermoplastic polymers, and recovery of the monomers basic constituents of said thermoplastic polymers.

[012] As will be detailed below and in the examples, such a process makes it possible to improve the production yield of base monomer.

[013] According to other optional characteristics of the process:

[014] - It comprises a step of purifying the base monomers previously recovered. Indeed, given that the thermoplastic polymers of the first and second articles to be recycled can be different, the process according to the invention can lead to the production of a large variety of monomers which can be separated during a purification step, for example a distillation. Indeed, the first and second articles to be recycled, although each comprising a polymer, preferably (meth) acrylic, may contain different comonomers and additives.

[015] - It comprises a step of removing the solid elements produced during the step of heating the first and second articles to be recycled. This allows, considering the presence of fibrous reinforcements and possibly fillers, to rid the recycling system of solid matter that can adversely affect performance, particularly in the context of a continuous recycling system.

[016] - The thermoplastic polymer matrix of the first article is a poly (methyl methacrylate) matrix. Poly (methyl methacrylate), which can be depolymerizable to methyl methacrylate (MAM) is particularly suitable for the process according to the invention.

[017] - The first article to be recycled and the second article to be recycled are introduced at a mass ratio of between 0.1 and 1.5, preferably at a mass ratio of between 0.1 and 0.5, more preferred to a mass ratio between 0.2 and 0.4. As shown in the examples such ratios allow a significant improvement in yields.

[018] The first article to be recycled has a percentage by mass of fiber reinforcement greater than 30%, preferably greater than 50%, more preferably greater than 70%. The higher the percentage by mass of fiber reinforcement in the article to be recycled, the lower the yield of base monomer recovery is usually. Nevertheless, under these low yield conditions, the gains made possible by the process according to the invention are high. Thus, while this type of material is very difficult to recycle by conventional techniques, the process according to the invention has a marked advantage. In particular, the percentage by mass of fibrous reinforcement corresponds here to the mass of fibrous reinforcement in the first article to be recycled relative to the total mass of the first article to be recycled.

[019] - The second article to be recycled is in the form of a syrup at room temperature (eg 25 ° C) and has a percentage by mass of thermoplastic monomer, preferably of (meth) acrylic monomer, equivalent greater than 80% , preferably greater than 90%, preferably greater than 95%.

[020] - In another embodiment, the second article to be recycled has a percentage by mass of monomer thermoplastic, preferably in equivalent (meth) acrylic monomer less than 95%, preferably less than 90%, preferably less than 80%, more preferably less than 70%. Indeed, although the invention can operate with cast plates of substantially pure thermoplastic methacrylic polymer, the invention allows a gain in combined efficiency of higher base monomer recovery when the second article has reinforcements, additives or fillers, without significant degradation of purity.

[021] - In another embodiment, the second article to be recycled has a percentage by mass of equivalent methyl methacrylate monomer of less than 95%, preferably less than 90%, preferably less than 80%, more preferably less than 70%. As previously, the invention allows a gain in combined yield of higher base monomer recovery when the second article presents polymers or copolymers not being based on methyl methacrylate. This is particularly advantageous when the thermoplastic polymer matrix of the first article to be recycled is RMMD.

[022] - The system suitable for recycling thermoplastic polymer is selected from:

• a depolymerization system in an extruder and / or conveyor,

• a rotating drum depolymerization system, and

• a depolymerization system on heating plates, preferably continuously.

[023] - during the heating step, the first and second articles to be recycled are heated to a temperature between 200 ° C and 1500 ° C, preferably at a temperature between 200 ° C and 600 ° C and advantageously at a temperature between 300 ° C and 600 ° C.

[024] - it further comprises moderate heating of the thermoplastic polymers, preferably (meth) acrylic, so to liquefy them at least in part. Such moderate heating allows liquefaction but not depolymerization. During moderate heating, thermoplastic polymers, preferably (meth) acrylic, are heated to a temperature between 200 ° C and 350 ° C, preferably at a temperature between 200 ° C and 325 ° C and advantageously at a temperature between 225 ° C and 300 ° C. It can be carried out at a temperature substantially equal to 270 ° C., such a temperature must be sufficient to allow the displacement of the liquefied thermoplastic polymers. Moderate heating can be moderate heating of the second item or moderate heating of the second and first item to be recycled. Carrying out moderate heating can improve efficiency gains.

[025] - recovery of the fibrous reinforcement from the first article to be recycled, said recovery being carried out by at least one of the following methods: centrifugation, draining, dewatering, pressing, filtering, sieving and / or cycloning. When heating the article to be recycled comprising a fibrous reinforcement, it is possible to separate the polymeric matrix of said article in order to recover the fibrous reinforcement in order to increase the degree of purity of the monomers subsequently recovered and optionally to reuse the reinforcement fibrous without it being degraded.

[026] The invention further relates to a system for recycling a first article to be recycled comprising a composite material based on fibrous reinforcement and a matrix of thermoplastic polymer, preferably (meth) acrylic, said system being characterized in that it includes:

• a means of conveying said first article to be recycled,

• a means of conveying a second article to be recycled comprising a thermoplastic polymer resin, preferably (meth) acrylic, and not comprising any fibrous reinforcement, and • a reactor suitable for heating the articles to be recycled and for the depolymerization of thermoplastic polymers, preferably (meth) acrylic, and the formation of base monomers of said thermoplastic polymers.

[027] Advantageously but not limitingly, a recycling system according to the invention comprises a second reactor suitable for the moderate heating of one of the articles to be recycled, preferably of the second article to be recycled, said second reactor comprising an opening arranged to communicate fluidly with the first reactor.

[028] In a particular embodiment, a recycling system according to the invention comprises a means of recovering basic monomers constituting thermoplastic polymers.

[029] In a preferred embodiment, a recycling system according to the invention comprises a means for setting in motion said first and second articles to be recycled.

[030] Other advantages and characteristics of the invention will become apparent on reading the following description given by way of illustrative and non-limiting example, with reference to the appended figures:

[031] [Fig 1] represents a diagram of steps of the recycling process according to one embodiment of the invention;

[032] [Fig 2] is an illustrative diagram showing an example of a recycling system according to one embodiment of the invention;

[033] [Fig 3] is a diagram of a side sectional view showing an example of a recycling system comprising an extruder according to one embodiment of the invention; and [034] [Fig 4] is a diagram of a side sectional view showing an example of a recycling system comprising heating supports according to one embodiment of the invention. [035] [Fig 5] is a diagram of a top sectional view showing an example of a recycling system comprising a rotating drum according to one embodiment of the invention.

[036] Aspects of the present invention are described with reference to flowcharts and / or block diagrams of methods or systems (or devices) according to embodiments of the invention. In the figures, flowcharts and block diagrams illustrate the architecture, functionality and operation of possible implementations of systems and methods according to various embodiments of the present invention. In this regard, each block in the flowcharts or block diagrams may represent a system, device or module for implementing the specified logic function (s). In some implementations, the functions associated with the blocks may appear in a different order than that shown in the figures. For example, two blocks shown in succession may, in fact, be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order, depending on the functionality involved.

[Description of the invention]]

[037] In the remainder of the description, the term “monomer” is understood to mean a molecule which can undergo polymerization.

[038] The term "polymerization" as used refers to the process of converting a monomer or a mixture of monomers into a polymer.

[039] The term “polymer” means either a copolymer or a homopolymer. A “copolymer” is a polymer grouping together several different monomer units and a “homopolymer” is a polymer grouping together identical monomer units.

[040] The term "depolymerization" as used relates to the process of converting a polymer into one or more monomer (s) and / or oligomer (s) and / or polymer (s) of reduced molecular weight relative to to the molecular mass of the initial polymer. [041] The term “base monomer” is understood to mean the most important constituent monomer unit of a polymer. Thus, in PMMA, the basic monomer is MAM.

[042] The term “thermoplastic polymer” or “thermoplastic” is understood to mean a polymer which, in a repeated manner, can be softened or melted under the action of heat and which takes on new forms by application of heat and pressure. Examples of thermoplastics are, for example: high density polyethylene (HDPE) used in particular for the production of plastic bags or for automobile construction; polyethylene terephthalate (PET) or even polyvinyl chloride (PVC) used in particular for the production of plastic bottles; Polystyrene (PS) used in the packaging and construction sector; Polymethyl methacrylate (PMMA). Thus, the use of thermoplastics affects a wide variety of sectors, ranging from packaging to the automotive industry, and the demand for plastic remains high.

[043] The term “thermoplastic monomer” is understood to mean the monomer or monomers or molecules which, after polymerization, are in the chain of a thermoplastic polymer.

[044] The term “thermoplastic (meth) acrylic polymer” or “(meth) acrylic polymer” is understood to mean a homopolymer or a copolymer based on (meth) acrylic monomer, which is for example chosen from methyl methacrylate, methacrylate ethyl, methyl acrylate, ethyl acrylate, methacrylic acid, acrylic acid, n-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, isobutyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, and mixtures thereof. Poly (methyl methacrylate) (PMMA) is a particular example of a (methacrylic) polymer obtained by polymerization of a methyl methacrylate monomer.

[045] The term “PMMA”, within the meaning of the invention, denotes homopolymers and co-polymers of methyl methacrylate (MAM), the weight ratio of MAM in PMMA preferably being at least 70%. by weight for the MAM copolymer. The term “copolymer based on methyl methacrylate” is understood to mean a copolymer having at least one methyl methacrylate monomer. For example, a methyl methacrylate-based copolymer can be a copolymer comprising at least 70%, preferably 80%, advantageously 90% by weight of MDM in the RMMD.

[046] The term “polymer matrix” means a solid polymer-based material serving as a binder in the context of a composite material. The “matrix” comprises polymers and / or oligomers and can also include additives and / or fillers. Thus, a “(meth) acrylic polymer matrix” refers to any type of matrix comprising acrylic and methacrylic polymers, oligomers or copolymers. However, it would not be departing from the scope of the invention if the (meth) acrylic polymer matrix comprised up to 49% by weight, preferably less than 40% by weight, of non-acrylic compounds, for example in the form of monomers, polymers, copolymers or block copolymers, chosen for example from the following group: lactic acid, butadiene, isoprene, styrene, substituted styrene such as α-methylstyrene or tert-butylstyrene, cyclosiloxanes, vinylnaphthalenes and vinyl pyridines.

[047] The expression “polymer resin” corresponds, within the meaning of the invention, to a solid material based on a polymer. The "polymer resin" includes polymers and / or oligomers and can also include additives and / or fillers. The polymer resin can be in solid or liquid form (in particular in the form of a syrup). The additives and / or fillers can in particular improve certain properties such as impact resistance or temperature resistance. Thus, a “(meth) acrylic polymer resin” refers to any type of resin comprising acrylic and methacrylic polymers, oligomers or copolymers. However, it would not be departing from the scope of the invention if the (meth) acrylic polymer resin comprised up to 49% by weight, preferably less than 40% by weight of non-acrylic compounds, for example in the form of monomers. , polymers, copolymers or block copolymers, chosen for example from the following group: methacrylonitrile, lactic acid, butadiene, isoprene, styrene, substituted styrene such as a- methylstyrene or tert-butylstyrene, cyclosiloxanes, vinylnaphthalenes and vinyl pyridines.

[048] For the purposes of the invention, the term “syrup” means a liquid composition exhibiting a dynamic viscosity of between 10 mPa * s and 10,000 mPa * s at 25 ° C. The dynamic viscosity of the syrup is in a range of 10 mPa * s to 10,000 mPa * s, preferably 20 mPa * s to 7000 mPa * s and more preferably 20 mPa * s to 5000 mPa * s. The viscosity of the syrup can easily be measured with a rheometer or viscometer. Dynamic viscosity is measured at 25 ° C.

[049] For the purposes of the invention, the term “composite” is understood to mean a multicomponent material comprising at least two immiscible components in which at least one component is a polymer and the other component may for example be a reinforcement such as 'a fibrous reinforcement or fillers.

[050] The term “reinforcement” is understood to mean a solid material which is not depolymerizable or gasifiable, such as a “fibrous reinforcement” or a “mineral filler” which generally remain at the end of recycling. [051] By "fibrous reinforcement" is meant a set of fibers, unidirectional rovings or a continuous filament mat, fabrics, felts or nonwovens which may be in the form of bands, plies, braids, wicks. or parts. In the context of the invention, a fibrous reinforcement will preferably correspond to a reinforcement comprising fibers of a length greater than 10 mm, more preferably greater than 20 mm and even more preferably greater than 3 cm.

[052] The term “mineral fillers” means any pulverulent fillers, for example quartz, marble, silica, aluminum hydroxide, titanium dioxide.

[053] The expression "mass ratio" within the meaning of the invention corresponds to a ratio relating to the weight of the articles to be recycled. [054] The expression "percentage by mass of equivalent methacrylic monomer" within the meaning of the invention corresponds to a theoretical content by mass of methacrylic monomer relative to the total weight of the article to be recycled. This percentage is preferably calculated without taking into account a possible methacrylic fraction which could be contained in fillers, additives, present in the mass of the article. A mass of monomer Theoretical methacrylic acid can correspond to a mass fraction originating from methacrylic monomers in a polymer or a copolymer.

[055] The expression "at least partly liquefy thermoplastic polymers" within the meaning of the invention corresponds to the initiation of a melting step (either greatly exceeding the glass transition temperature T _g and / or the temperature of melting T _f , the latter only for a crystalline or semi-crystalline polymer) at least partial of the thermoplastic polymers contained in the articles to be recycled. Depending on the polymers considered, the temperature must allow the molten thermoplastic polymer to have a sufficient viscosity to allow the extrusion of the polymer without completely decomposing it.

[056] For the purposes of the invention, the term “substantially equal” means a value varying by less than 30% with respect to the compared value, preferably less than 20%, even more preferably less than 10%.

[057] In the description of the embodiments which will follow and in the appended figures, the same references are used to designate the same elements or similar elements.

[058] The recycling of materials and even more of composite materials requires the taking into account of numerous parameters so that the recycling presents a more favorable carbon and energy balance compared to the energy balance of the initial manufacture.

[059] In particular for the recycling of composite materials with a thermoplastic polymer matrix, preferably (meth) acrylic, the technical problem to be solved is to increase the productivity during the depolymerization of composites with a thermoplastic (meth) acrylic polymer matrix. . Indeed, the solutions conventionally provided consist in increasing the depolymerization temperature. But in the case of a thermoplastic (meth) acrylic polymer matrix, the increase in temperature has little effect on the rate of depolymerization.

[060] Surprisingly, the inventor has discovered that when one proceeds to mixtures of composites and of different grades of thermoplastic polymer matrix, advantageously but not limited to (meth) acrylic, the yield of monomer obtained in a given period of time is improved. This is understood to mean that the yield is greater than what it would have been by depolymerizing the two fractions independently over the same period.

[061] Thus, the inventor has developed a process for recycling composite materials based on a thermoplastic polymer matrix, preferably (meth) acrylic, exhibiting an improved monomer yield. As will be presented in the examples, the gain in yield is all the more marked for certain mass ratios between the composite and the other grades of thermoplastic polymer matrix, preferably (meth) acrylic. Further, there is also provided a recycling system capable of implementing such a method.

[062] The present invention makes it possible to obtain a satisfactory production of methyl methacrylate, in particular from materials based on a (meth) acrylate matrix that are poorly recyclable (i.e. having a low production yield of methyl methacrylate).

[063] The present invention therefore relates in particular to a process for recycling an article made of coirqposite material. The article made of composite material, or first article 10 to be recycled, can in particular be an article made of composite material based on a fibrous reinforcement and on a matrix of thermoplastic polymer, preferably a matrix of thermoplastic (meth) acrylic polymer. In particular, it should be noted that the article to be recycled may be a manufactured product or part of a manufactured product at the end of its life, or a production waste of such a product. In both cases, a preliminary sorting step may be necessary in order to eliminate the non-depolymerizable waste or any non-depolymerizable product also contributing to energy efficiency losses.

[064] The article made of composite material, or first article 10 to be recycled, can also comprise other polymers apart from the thermoplastic polymer matrix of the composite material based on fibrous reinforcement. It could be glue, foam, gel-coat or other polymers of a different nature from the matrix of thermoplastic polymer of the composite material. In this case, a fractionation step 105 may prove to be necessary either upstream 105a or downstream 105b, in order to eliminate these other polymers or to reduce the quantity of these other polymers. Preferably the fractionation step 105, if it will take place, is done upstream: the fractionation step 105b, more preferably before the grinding step 110.

[065] As has been mentioned, composite materials based on fiber reinforcement exhibit yields of recycled monomers, whether molar or by mass, which are lower than non-composite materials (eg yields calculated after recovery of a condensate and separation of base monomers based on theoretical base monomer content). However, the present technology is particularly suited to such materials. A mass yield of base monomer recovered relative to the equivalent monomer can be calculated by taking into account the mass content of monomer recovered from the condensate and the theoretical mass content of monomer in the article to be recycled. However, such a calculation presupposes being able to determine the theoretical monomer mass content in the recycled article. This is possible in certain controlled experiments but proves to be more difficult during the industrial use of the invention. Thus, in the examples, an improvement in mass yield is mentioned. This is based on an increase in the mass of base monomer recovered using a process according to the invention compared to a mass of base monomer recovered with the techniques of the prior art.

[066] In the composite material, the thermoplastic polymer matrix is intimately linked to the reinforcement. Fibrous reinforcement can be seen as a reinforcement, often based on glass or carbon fibers. For example, the fibrous reinforcement can be a fabric, webs, felts or any other fibrous material. The fibrous reinforcement will for example be based on glass fibers, carbon fibers or basalt fibers, or also metal or plant fibers. [067] The thermoplastic (meth) acrylic polymer can be a homopolymer or a copolymer based on (meth) acrylic monomer, which is for example chosen from methyl methacrylate, ethyl methacrylate, methyl acrylate, l 'ethyl acrylate, methacrylic acid, acrylic acid, n-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, isobutyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate and mixtures thereof.

[068] In particular, the composite material of the article to be recycled is based on RMMD and fiber reinforcement.

[069] The main steps of a recycling process according to the invention are detailed in FIG. 1. In particular, a recycling process 100 according to the invention comprises an introduction 130 of a first article 10 to be recycled into a system. 1 adapted for the recycling of thermoplastic polymer, an introduction 140 into the system 1 of a second article 20 to be recycled comprising a thermoplastic polymer resin, preferably (meth) acrylic, but not comprising any fibrous reinforcement, a heating 150 of the articles at a given temperature and a recovery 160 of the basic monomers constituting the thermoplastic polymers, preferably (meth) acrylic. The second article 20 to be recycled can also contain additives to improve certain properties: for example impact resistance, temperature resistance. Generally, such additives can interfere with depolymerization.

[070] The second article to be recycled can also be in the form of a syrup at room temperature and have a percentage by weight of thermoplastic monomer, preferably of equivalent meth (acrylic) monomer, greater than 70%, for example greater than 75. %, preferably greater than 80%, more preferably greater than 90%, even more preferably greater than 95%. Indeed, such a syrup is obtained either during the preparation of cast plates during the prepolymerization of methyl methacrylate, or by dissolving RMMD in methyl methacrylate. Preferably when using the second item, a polymerization inhibitor additive is added to the second item. Such an additive can be hydroquinone, MEHQ (4-Methoxyphenol), phenothiazine, Topanol (2,4-Dimethyl-6-tert-butylphenol). Such a syrup can advantageously but without limitation consist of an Elium® resin in liquid form. [071] In addition, as will be detailed below, a process 100 according to the invention can comprise stages of fractionation 105, of grinding 110, of sorting 120, of purification 170 of the base monomers previously recovered, of elimination 180. solid elements produced during the heating step.

[072] The present invention involves the joint recycling of two articles having different grades. In particular, a first article is a composite material comprising a fibrous reinforcement while a second article does not include a fibrous reinforcement.

[073] In addition, as will be detailed below, it is in particular this combination of materials having different grades that allows the present invention to achieve higher monomer yields than the yields of these separately recycled materials. Thus, the present invention makes it possible to achieve correct monomer yields, that is to say at least greater than the yields of these materials recycled separately, from materials generally considered to be poorly recyclable.

[074] The grade system is a classification specific to industries specializing in the manufacture of materials and in particular composite materials. This system makes it possible to reflect the quality of a material and in part its composition. Thus, the grade of a material will for example be influenced by: the presence or absence of reinforcement, and the type of reinforcement used, the characteristics of the matrix used: the polymer or the possible combination of polymer forming the matrix, with by example the presence or not of a crosslinking, and the presence or not of additives.

[075] Thus, in the context of the present invention, the first article to be recycled 10 preferably has a first grade while that the second article to be recycled 20 has a second grade different from the first grade.

[076] In particular, the first article 10 to be recycled comprises a fibrous reinforcement while the second article 20 to be recycled does not include any fibrous reinforcement.

[077] The first article 10 to be recycled, as well as the second article 20 to be recycled, may comprise additives such as plastic additives, additives to improve the temperature resistance, additives to improve the impact resistance, co -monomers, for example acrylates or the like to block / slow down depolymerization. They can also contain mineral fillers such as alumina, quartz, marble, aluminum hydroxide and titanium oxide. In particular, the thermoplastic polymer, preferably (meth) acrylic, can comprise at least one additive such as a stabilizer, a pigment, a plasticizer such as phthalates, an adhesion promoter, a UV absorber, an antioxidant, a flame retardant, colorant, lubricant, mold release agent, antistatic agent, fungicide, surfactant and / or crosslinked polymer beads, impact resistance additive, etc. Indeed, the addition of an additive generally makes it possible to improve the properties of the thermoplastic composition. For example, fillers improve thermal or chemical resistance, plasticizers reduce stiffness, stabilizers prevent degradation of polymers, antistats prevent dust deposit, lubricants limit wear, flame retardants provide better fire resistance etc. However, the presence of such additives usually presages a low yield of base monomer recovery in the event of recycling by depolymerization.

[078] Preferably, the second article 20 to be recycled comprises at least 50% by mass of thermoplastic polymer, for example (meth) acrylic, more preferably at least 60% by mass of thermoplastic polymer, for example (meth) acrylic and even more preferably at least 70% by mass of thermoplastic polymer, for example (meth) acrylic. [079] In addition, the second article 20 to be recycled is advantageously not an article considered usually easily recyclable. Thus, it can preferably comprise at least 5% by mass of filler (such as a mineral filler), more preferably at least 10% by mass of filler and even more preferably at least 15% by mass of filler.

[080] In a particular embodiment, the second article 20 to be recycled comprises at least between 0.5% and 25% by weight of acrylic or non-acrylic comonomer, preferably between 1% and 10% by weight.

[081] Preferably, the second article 20 to be recycled comprises at least 5% by mass of additives relative to the total weight of thermoplastic composition, for example (meth) acrylic, preferably at least 10% by mass, more preferably at least 15% by mass.

[082] Preferably, the second article 20 to be recycled comprises up to 50% by weight of additives relative to the total weight of thermoplastic composition, for example (meth) acrylic, preferably less than 40% by weight, more preferably less than 30% by weight, even more preferably less than 25% by weight. Advantageously but not restrictively, the second article 20 to be recycled comprises up to 50% by mass of an additive of acrylic impact modifier type and / or methacrylate-butadiene-styrene and / or acrylic processing agents, preferably up to at 25%. The function of such an impact modifier additive is to improve the impact resistance of thermoplastics. In a particular embodiment, the second article 20 to be recycled comprises up to 30% of an additive of the poly lactic acid type. The poly lactic acid additive is a thermoplastic resin obtained from renewable plant resources and is certified compostable. Such a resin can also be combined with additives of the impact modifier type.

[083] In particular, the second article 20 to be recycled may comprise an at least partially crosslinked thermoplastic polymer resin.

[084] As shown in Figure 1, a recycling process 100 according to the invention may include a preliminary step of sorting 120. The sorting step can be a step in which the first article 10 to be recycled comprising a composite material based on fibrous reinforcement is separated and isolated. For example, it can be separated and isolated from articles not comprising composite material, and / or it can be separated and isolated from contaminants such as glass, sand, wood, other polymers, foams or chemicals. metals. The sorting step also allows the separation and sorting of plastics by family. For example, it is possible to sort thermoplastic polymers on the one hand and thermosetting polymers on the other hand, as well as different thermoplastics between them. Sorting can also make it possible to eliminate portions resulting from the grinding which are not made of composite material.

[085] Sorting can be carried out by any sorting method suitable for recycling polymer. One possible sorting method may involve a settling system in which the waste is placed in a tank of water and / or brine, or an organic liquid. The heavy elements are found at the bottom of the tank, and can be evacuated via a pneumatic lock system. The elements to be recycled can be extracted from the bin using a worm screw (at the top or at the bottom depending on their density). Sorting can also include magnetic sorting in order to extract metal particles. Sorting can also include eddy current separation to remove certain metals such as copper and aluminum. It is also possible to combine separation technologies such as, for example, sorting by density in a solution, and magnetic separation. The sorting method can use spectroscopic technologies such as Raman or Infra-red, in order to recognize the composition of materials. Sorting methods using the triboelectric properties of the materials or their hot adhesion properties can also be used. Sorting can be carried out in a sorting center. The sorting step advantageously makes it possible to remove elements which could damage the various devices used in the implementation of the recycling process 100.

[086] In addition, for example in order to facilitate the introduction of the article into the reactor suitable for recycling polymer, the article can be ground beforehand. Thus, in one embodiment, the method 100 for recycling the article comprises a step of grinding 110 of the article, carried out before step 120 of FIG. 1 - and in this case it is necessary acts more like crushing than fine grinding because sorting operations are facilitated. The grinding step makes it possible to reduce the dimensions of the article to be recycled (the first and / or the second) and can for example be carried out using any suitable mechanical crusher. Contactless grinding technologies can also be used. The first and second articles to be recycled are reduced to dimensions allowing the introduction of the ground material thus obtained into a device suitable for recycling according to the invention. The particles obtained after grinding may for example have dimensions (eg radius, diameter, median diameter, length, width, height, etc.) such that at least one dimension is between 1 mm and 100 mm, preferably between 3 mm and 50 mm. mm. Preferably, at least one of the dimensions of the second article to be recycled 20 is less than 30 mm. The first and second articles to be recycled can then take the form of chips, granules or powder. More preferably, the grinding is carried out so that the second article to be recycled has at least one of its dimensions smaller than the largest dimension of the first article to be recycled. The first and second articles to be recycled can also be in the reactor in one or more of the aforementioned forms. Advantageously, the grinding / crushing step 110 can make it possible to facilitate a sorting step. It is, however, in general, easier to sort large parts, provided that their composition is homogeneous. The purpose of the grinding operation is therefore also to create pieces that are homogeneous in composition. This is why it can be implemented before the sorting operations described above. The grinding operation could also be selective grinding. [087] As illustrated in FIG. 1, a recycling process 100 according to the invention comprises a step 140 of introducing the first article 10 into a system 1 suitable for recycling thermoplastic polymer. In particular, the first article 10 can be introduced into a reactor suitable for recycling polymer. [088] For example, the introduction of the first article 10 to be recycled into the reactor can be carried out using an endless screw, a conveyor belt, a hopper or by a metering module. The feed rate to the reactor of a first article to be recycled 10 can be between 10 kg / h and 2000 kg / h, and preferably between 50 kg / h and 500 kg / h, preferably between 100 kg / h and 400 kg / h.

[089] A recycling method 100 according to the invention also comprises a step 120 of introducing a second article 20 to be recycled into the system 1 suitable for recycling thermoplastic polymer.

[090] The first article 10 and the second article 20 can be introduced successively or simultaneously into the system and in particular into a depolymerization reactor. Thus, the second article 20 to be recycled not comprising any fibrous reinforcement can be introduced before the first item 10 to recycle.

[091] Alternatively, the first article 10 and the second article 20 may have been mixed and be introduced simultaneously into the recycling system 1 and in particular into a reactor suitable for recycling polymers. The first and second articles 10, 20, introduced for example in the form of granules, chips, needles, plates or even powders have a substantially different particle size. Advantageously, the article 10 to be recycled has dimensions greater than the article 20 to be recycled. The method 100 may also include the introduction of several other articles comprising a thermoplastic polymer, preferably a thermoplastic (meth) acrylic polymer.

[092] Preferably, the first article 10 to be recycled comprising a composite material based on fibrous reinforcement and on a thermoplastic polymer matrix, advantageously (meth) acrylic, and the second article or articles 20 to be recycled based on thermoplastic polymer resin, of preferably (meth) acrylic, without fibrous reinforcement are introduced at a mass ratio (second article (s) / first article) between 0.1 and 1.5, preferably at a ratio between 0.1 and 0 , 5 and more preferably at a ratio between 0.2 and 0.4.

[093] As shown in Figure 1, a recycling process 100 according to the invention also includes a step of heating 150 of the first and second articles 10, 20. The heating can in particular be carried out in a reactor of a system 1 suitable for recycling thermoplastic polymer, preferably for recycling a composite article comprising thermoplastic polymers.

[094] Preferably, the system 1 suitable for recycling thermoplastic polymer resin is selected from: an extruder / conveyor depolymerization system, a rotating drum depolymerization system, and a depolymerization system on heating plates operating for example continuously.

[095] The heating is carried out at a temperature making it possible to depolymerize the thermoplastic polymers, preferably (meth) acrylic, and to form base monomers of the thermoplastic polymers of the first and second articles 10,20.

[096] In particular, the heating of the article is carried out at a given temperature allowing the depolymerization of the thermoplastic polymer and the generation of a base monomer in the gaseous state. The heating can for example be carried out at a temperature between 200 ° C and 1500 ° C, preferably between 300 and 600 ° C, more preferably between 350 and 500 ° C and even more preferably between 400 and 450 ° vs. The heating can still be stepped, with a first heating zone at a moderate temperature, followed by a second or second, and therefore multiple heating zones at increasing temperature. The moderate temperature is preferably between 200 and 350 ° C, more preferably between 200 and 300 ° C.

[097] In a preferred embodiment, the heating of the articles to be recycled 10.20 is carried out under an inert atmosphere, for example under vacuum, under nitrogen, under CO2 or under argon or substantially low in oxygen (for example 0.1 % to 10% oxygen). Such an oxygen-depleted atmosphere can, for example, be obtained by recycling the combustion gases from the light effluents from the depolymerization unit. [098] Likewise, advantageously, a method 100 for recycling the article according to the invention comprises a moderate heating step 151 of the first and / or of the second article to be recycled. More preferably, a recycling process 100 according to the invention comprises a moderate heating step 151 of the second article to be recycled. This moderate heating step of the item (s) to be recycled can be carried out before their introduction into the reactor and, where appropriate, after grinding. Moderate heating can be achieved using any suitable heating means. Alternatively, it can be initiated in the reactor suitable for polymer depolymerization. The temperature to which the article is preheated may be 50 ° C or more, for example 200 ° C. By moderate heating of the article (s) to be recycled, part of the polymer can be melted or the liquid state and / or depolymerization of the polymer matrix can be facilitated. [099] A recycling process 100 can lead to the destructuring of the polymer matrix and to its conversion, for example, into a mixture in the molten or liquid state. Thus, the heating step 150 can integrate a step 152 for recovering the fibrous reinforcement. Such a step of recovering a fibrous reinforcement can be carried out during the heating step or after the latter has been completed. In particular, the step of recovering the fibrous reinforcement can take place once the recovery of the monomers has been carried out.

As shown in Figure 1, a recycling process 100 according to the invention also comprises a step 160 of recovering the basic monomers constituting the thermoplastic polymers, preferably (meth) acrylic.

Advantageously, a process 100 according to the invention can comprise a step of condensing these base monomers from the gaseous state to the liquid state so as to obtain a solution comprising the base monomers.

Preferably, this condensation can be carried out by bringing monomers in the gaseous state into contact with monomers in the liquid state. This contacting can for example be carried out in a device of the shower type, by sprinkling the monomers in the liquid state (ie cold) in an enclosure collecting the base monomers in the gaseous state (ie hot). In this case, the device can comprise a means for introducing a stabilizer, or polymerization inhibitor.

Furthermore, the condensation of the gas mixture can be carried out in a fractional manner and lead to cleaner fractions containing the base monomer, and less clean fractions containing monomer and contaminants. This fraction containing contaminants can also be reintroduced into the reactor in order to allow better separation of the monomers contained in this fraction.

A recycling process 100 according to the invention can also include a step 170 for purifying the base monomers recovered beforehand.

The purification step 170 may include a step of separation by distillation, for example by means of a distillation column. In fact, during depolymerization, impurities can be formed which must be eliminated subsequently. A recycling process 100 according to the invention may also include a step 180 for removing the solid elements produced during the step of heating the first and second articles 10,20. The separation means for the removal of solid elements is adapted to the state of the matrix in the reactor or at the outlet of the reactor, i.e. depending on whether the matrix is converted into a mixture in the molten or liquid state, or is converted to a mixture in the gaseous state. In the case where the reinforcement is contained in a mixture in the molten or liquid state, the separation means can be any means allowing a solid / liquid separation, such as a grid for example. The separation can also be done by centrifugation using a centrifuge, or else by decantation, filtration, draining, spinning, pressing or sieving. Preferably, the separation is carried out by filtration in a molten medium, pressing or settling. In the event that the matrix is gasified / depolymerized, the gas phase separation means may comprise a cyclone or filters, for example. When filters are used, back pressure is applied periodically to loosen the solid that has accumulated at the filter. The solid cake is then recovered below the filter in a capacity provided for this purpose. It should be noted that during the depolymerization of the matrix, Polymer residues can remain on the reinforcement, and the solid phase separation of the solid residues can be carried out for example by sieving (separation of glass fiber / carbon powder, etc.). This removal step advantageously makes it possible to treat the different types. solid residues which form during the depolymerization reaction, namely the solid residues entrained in the gas phase and the solid residues which remain compact which will be found in particular at the reactor outlet. The solid residues entrained in the gas phase have the potential to clog the condensing unit of the monomer. These solid residues must therefore be filtered in the gas phase (for example via a suitable separation means: cyclone, filters) or in the liquid phase after the condensation, while the solid residues which flow out at the reactor outlet generally remain in the form of solid mat which can be sieved, for example to separate the various solid residues. Hot solid residues must / can be cooled, for example by direct contact with water. During this cooling step, direct contact between the solid and the monomer must be limited to prevent the latter from re-condensing directly on the solid.

[0107] According to another aspect, the invention relates to a system 1 for recycling a first article 10 comprising a composite material based on reinforcement and a matrix of thermoplastic polymer, preferably (meth) acrylic.

As illustrated diagrammatically in FIG. 2, the recycling system 1 according to the invention comprises a conveying means 11 of a first article 10 comprising a composite material based on fibrous reinforcement and a matrix of thermoplastic polymer, for example (meth) acrylate, a conveying means 21 of a second article 20 to be recycled comprising a resin of a thermoplastic polymer, preferably (meth) acrylic. The conveying means 11, 21 can be a pipe, a worm, a conveyor belt, or a hopper, a pneumatic transport, a vibrating conveyor, an extruder. In addition, they can be coupled to a metering device. The recycling system 1 according to the invention also comprises a reactor 50 suitable for the heating articles 10, 20 for the depolymerization of thermoplastic, preferably (meth) acrylic polymers, and formation of monomers. For example, heating can be achieved by exposing the article to microwaves, pulsed electric fields, or water vapor, by contact with a hot surface such as in an extruder, screw conveyor. , a rotating drum ... The hot surface can be heated by different means: direct electric heating, heating by heat transfer fluid (water vapor, oil, molten salts ...).

The recycling system 1 according to the invention also comprises a means 60 for recovering constituent monomers of thermoplastic polymers, advantageously but not limited to (meth) acrylic.

[0110] In addition, a recycling system 1 according to the invention may comprise one or more means for setting the first 10 and second 20 articles to be recycled in motion, one or more video acquisition means 356, described in connection with the Figure 4, such as an infrared camera, one or more purification means 70 and one or more solids removal means 80.

The reactor of a system 1 according to the invention can be an extruder or conveyor, a reactor suitable for pyrolysis, for pyrolysis at high temperature, for pyrolysis in a bath of molten salts, or a fluidized bed reactor. or a reactor suitable for solvolysis or else a reactor consisting of hollow plates heated by a heat transfer fluid circulating in the plates. Nevertheless, reactors have been identified which allow higher monomer yield gains, such as: an extruder, a conveyor, an extruder-conveyor, a rotating drum and / or a set of heating plates.

A reactor suitable for recycling thermoplastic polymer can also be a pyrolysis reactor, for example a multistage pyrolysis reactor or a stirred rotary cylinder reactor. Two configurations are possible: either the cylinder rotates on its axis, or an internal agitation system ensures mixing and heat transfer from the wall to the polymer. An extruder-conveyor is a reactor comprising one or more endless screws each actuated in a sleeve, in particular allowing the stirring of the elements introduced into said sleeve. The use of an extruder-conveyor for the implementation of the recycling process 100 is advantageous from an environmental, safety and security point of view of the process 100. In fact, an extruder-conveyor makes it possible to treat polymers. high viscosity melts without resorting to the addition of solvent to decrease the viscosity of the molten polymers. The extruder-conveyor has the advantage of allowing efficient heat transfer from the sleeve to the composite to be treated. The extruder can advantageously be replaced by a screw conveyor system over all or part of its length. Advantageously, the system can comprise the combination of a first part conveyor-type device, followed by an extruder-type device and terminated by a conveyor-type device configured to transport the solid (ie reinforcement) to the outlet. conveyor can be of the “Auger screw” or “Archimedean screw” type.

[0114] With reference to FIG. 3, a recycling system 1 according to the invention may comprise an extruder, more particularly a twin-screw extruder 200 comprising an orifice 201 through which a first article 10 to be recycled comprising a composite material based on fiber reinforcement and a matrix of thermoplastic polymer, preferably (meth) acrylate can be inserted for example by means of a metering device 210 and a conveying means 211. Likewise, a second article 20 to be recycled comprising a resin of thermoplastic polymer, preferably (meth) acrylic can be inserted for example by means of a metering device 220 and a conveying means 221. The first and second articles 10, 20 to be recycled can be in the form powder or granulate. Alternatively, the articles can be introduced into the extruder after having undergone a first heating step. [0115] Thus, the first and second articles 10, 20 to be recycled are introduced hot or cold and can also be heated and / or maintained at temperature during the treatment. A twin-screw extruder can be, for example, an extruder of the Clextral® type. The twin-screw extruder comprises two screws 204, most often parallel, rotating inside a sleeve 250. Advantageously, the extruder has a modular character, that is to say that the screw and the sheath 250 are modules assembled in series, and the assembly of which can be modified. Thus, the sleeve 250 corresponds here to the reactor suitable for heating the articles 10, 20 with a view to the depolymerization of the thermoplastic polymers, by way of nonlimiting (meth) acrylic example, of the recycling system 1 according to the invention. More generally, the reactor 50 of the system according to the invention can take different forms provided that the gas flows and the temperature can be controlled.

[0117] In the extruder, an external heating means 255 regulating the temperature of the sleeve 250 is advantageously configured to heat the first and second articles 10, 20 to be recycled and to bring the polymeric matrix and the polymeric resin in the molten state. The temperature in the reactor can be between 50 ° C and 550 ° C and it can be controlled by means of temperature sensors not shown in the figure.

[0118] The depolymerization can lead to products in the form of gases which are extracted out of the extruder in order to be treated. The solid residues are for their part removed by suitable means 202. In particular, the reactor is able to operate under vacuum or under a gas flow, in order to take the monomer which forms to a condensation unit via a collection means. The gases produced can be directed via a conduit 208 to a recovery device 260 in order to be condensed. The condensate obtained can then be collected in a chamber 209 provided for this purpose. In order to allow the recovery of gas resulting from the implementation of the recycling method 100, the system 200.1 suitable for recycling can comprise one or more purification devices. For example, the system may comprise a purification device, not shown in the figures, which may correspond to a separation system by distillation, for example a distillation column. The distillation column allows the separation of compounds according to their boiling point.

Another type of advantageous system for recycling a first article 10 comprising a composite material based on fibrous reinforcement and a thermoplastic polymer matrix, preferably (meth) acrylic, comprises a device consisting of hollow plates , heated by a heat transfer fluid circuit (pressurized steam, oil, molten salts). During its treatment the article advances on the plates of increasing temperatures at first. The solid residue ends its passage in the reactor by passing over plates which are at a lower temperature and where the heat exchange takes place from the residue to the coolant. The heat transfer fluid thus heated can then be used to preheat the article towards the inlet of the reactor.

[0121] Thus, in particular and with reference to the diagram of FIG. 4, a recycling system 300 according to the invention comprises an enclosure 350 equipped with heating plates 351, 352. The system comprises in particular two reservoirs 312, 322 making it possible to respectively storing the first article 10 to be recycled and the second article 20 to be recycled. These reservoirs are connected to the enclosure 350 by means of delivery pipes 311, 321 and make it possible to introduce therein said articles to be recycled, preferably crushed / crushed / delaminated beforehand in the appropriate particle size. As illustrated in Figure 4, the system includes one or more heating supports 352 (such as a hot plate) onto which the second item 20 to be recycled is fed and configured to allow the temperature rise of the thermoplastic polymer which will begin. to be melted under the effect of the temperature before falling on a second heating support 351. Alternatively and according to a configuration not shown, a recycling system according to the invention is arranged so as to allow the first article 10 to be recycled to fall on the second article 20 to be recycled, said second article to be recycled having previously undergone moderate heating. [0122] In addition, the system may include a means for setting in motion 355 (for example actuated by a piston, blades or claws) arranged to push the second article 20 towards a second heating support 351. As illustrated, the second heating support

351 (such as a hotplate) is arranged to receive the first article 10 to be recycled and to contact it with the second article 20 to be recycled at least partially molten. Further, the second heating medium 351 is configured so as to allow the polymer matrix to depolymerize under the effect of temperature. In the enclosure 350, the first and second articles 10, 20 to be recycled are heated and the polymeric matrix and resin are depolymerized thanks to the heating supports 351,

352 at regulated temperature. The system is then configured to maintain a temperature high enough to depolymerize the thermoplastic polymers, preferably (meth) acrylic. The temperature in the enclosure can be between 50 ° C and 550 ° C and it can be controlled by means of temperature sensors not shown in Figure 4. The system can then be arranged to push the mixture of the first and second articles 10, 20 to be recycled to a third heating medium (or multiple cascading stages) or to a separation means 381 such as a screen or a screen allowing the solid residues to be separated according to their diameter. Such a separation means can for example be used to separate the fiber residues 15 from the other fillers which may be contained in the second article 20 to be recycled. In addition, the separation means 381 can be coupled to a moving means 382 (e.g. piston, motor) making it possible to improve and / or accelerate the separation. The solid residues can then be removed by suitable means 302.

In the reactor, the polymers, preferably meth (acrylic), are depolymerized under the action of heat to in particular lead to the methyl methacrylate monomer, in the case of articles to be recycled composed of thermoplastic meth (acrylic) polymer. ), in the form of gas. The produced gases 358 can be directed through a conduit 359 to a cooling system 360 in order to be condensed. The condensate obtained can then be collected in a chamber provided for this purpose. The enclosure as well as the chamber are preferably under negative pressure or under a gas flow, in order to carry the monomer which is formed towards a condensation unit. A condensation unit is more particularly suitable for condensing the mixture of base monomer in the gaseous state. In addition, as previously presented in connection with FIG. 3, the reactor is able to operate under vacuum or under a gas flow, in order to take the monomer which forms to a condensation unit via a collection means. In particular, the gases produced can be directed via a conduit 359 to a recovery device 360 in order to be condensed. The condensate obtained can then be collected in a chamber 309 provided for this purpose. In order to allow the recovery of gas resulting from the implementation of the recycling process 100, the system 300 suitable for recycling can comprise one or more purification devices. For example, the system may comprise a purification device, not shown in the figures, which may correspond to a separation system by distillation, for example a distillation column. The distillation column allows the separation of compounds according to their boiling point.

[0124] In addition, the gases produced in the reactor can be entrained towards a gas / solid separator such as a cyclone. Such a separator can be internal or external to the reactor. There may also be a multiplicity of separators in series, internal and external, having the objective of recovering the particles of the reinforcement. Thus, the solid particles entrained in the gas phase are filtered / separated either in the gas phase before the condenser or in the liquid phase after the condenser.

[0125] In a third embodiment, the system suitable for recycling a first article 10 comprising a composite material based on fibrous reinforcement and on a matrix of thermoplastic (meth) acrylic polymer, comprises a device of the mixer type. -conveyor, for example a mixer-conveyor of the “Paddle Dryer” type. This device comprises a reactor in which a propeller / rotating blade is arranged. The propeller therefore makes it possible to mix and homogenize a mixture of a first article and a second article to be recycled. The mixer-conveyor presents the advantage of allowing the treatment of large quantities of solid waste / residues. It also allows good heat transfer between the wall and the waste. Such a device can be used at low temperature to dry a solid, but in the context of the invention, by increasing the temperature, it is possible to induce depolymerization.

A fourth embodiment of a recycling system 400 according to the invention is illustrated in FIG. 5. Such a system can comprise a device of the rotating drum type in which the entire reactor is rotated according to a longitudinal axis. Alternatively, the drum is fixed and it is a propeller / blade which turns (Paddle-dryer type).

[0127] The device of the rotating drum type advantageously comprises a reactor 450 comprising an orifice 403 through which a first article 10 to be recycled, comprising a composite material based on fibrous reinforcement and on a thermoplastic polymer matrix, preferably (meth). acrylic, can be inserted for example by means of a metering device 410 and a conveying means 411. Likewise, a second article 20 to be recycled comprising a resin of thermoplastic polymer, preferably (meth) acrylic, can be inserted for example by means of a metering device 420 and a conveying means 421. As described above, a reactor of a system according to the invention can take different forms provided that the gas flows and the temperature can be controlled, thus a reactor of a system according to the invention can be adapted to a device of the rotating drum type.

[0128] The first and second articles 10, 20 to be recycled can be in the form of powder, granule or have been crushed. In this embodiment, the orifice 403 is arranged to receive the first article 10 to be recycled by the conveying means 411 of the metering device 410 and the second article 20 to be recycled by the conveying means 421 of the metering device 420.

[0129] In order to improve the relative yield for the production of base monomer from thermoplastic polymers obtained from articles 10, 20 to be recycled, a system 1 in accordance with the invention may comprise a second reactor 480 suitable for the moderate heating of one of the articles 10, 20 to be recycled. Advantageously but without limitation, such a reactor 480 may correspond to a single-screw or twin-screw extruder 200, as described in connection with FIG. 3, and comprises one or two screws 404 rotating inside said second reactor 480.

In this embodiment, the reactor 480 comprises an orifice 401 through which said first and second article 10, 20 to be recycled can be inserted for example via the metering devices and the previously mentioned conveying means. Preferably, the second article 20 to be recycled is introduced through the orifice 401 of the reactor 480 and will undergo moderate heating during its passage through said reactor.

Like the heating means of the twin-screw extruder 200, an external heating means 455 regulates the temperature of the reactor.

450 and is advantageously configured to heat the second article 20 to be recycled and bring the polymeric resin to the molten state without inducing depolymerization. The temperature in the reactor can be between 200 ° C and 350 ° C and it can also be controlled by means of temperature sensors not shown in the figure.

Such moderate heating advantageously makes it possible to liquefy all or part of the polymeric resin of the article 20 to be recycled so that the latter is conveyed to the reactor 450 in the form of a viscous mixture via an orifice 402 arranged for allow fluid communication between said reactors 450 and 480. Thus, the article 10 to be recycled is preferably added directly after the entry of the article 20 to be recycled by mechanical or pneumatic transport, into the reactor 450.

[0133] In addition, the reactor 450 may include a motor source (not shown) driving said reactor 450 in rotation about a fixed axis 451, in the case of a rotating drum, or of an axis

451 rotating in the case of a reactor 450 of a paddle dryer type mixer-conveyor. Such an axis 451 can advantageously comprise one or more means for setting in motion 452, or else one or more several mixer elements, fixed along said axis. Such means for setting in motion can advantageously take the form of a blade or even of a propeller, having any geometric shape suitable for mixing the articles 10, 20 to be recycled. The moving means 452 therefore makes it possible to mix and homogenize a mixture of a first article 10 and of a second article 20 to be recycled.

[0134] An appropriate means of movement is chosen as a function of the nature and size of the articles 10, 20 to be recycled, which are in the form of powder or granules.

Finally, the reactor 450 can advantageously comprise an external heating means 455 regulating the temperature of the reactor 450 and configured to heat the articles 10, 20 to be recycled and carry the polymeric matrix of the article 10 to be recycled and the polymeric resin. of article 20 to be recycled in the molten state. As previously described in connection with FIG. 2, the heating can still be staged, with a first heating zone at a moderate temperature, followed by a second or second, and therefore multiple heating zones at increasing temperature.

[0136] In a manner analogous to the system 1 described in connection with FIG. 3, the depolymerization can lead to products in the form of gases which are extracted out of the device in order to be treated. In particular, the reactor 450 is able to operate under negative pressure or under a gas flow, in order to take the monomer which forms to a condensation unit via a collection means. The gases produced can be directed via a conduit 408 to a recovery device 460 in order to be condensed. The condensate obtained can then be collected in a chamber 409 provided for this purpose. The system presented in connection with FIG. 5 can also comprise a purification device, not shown in the figures, which may correspond to a separation system by distillation, for example a distillation column, as described in connection with figure 3.

Thus, once the articles 10, 20 to be recycled have been introduced and brought into contact in the reactor 450, the latter will undergo depolymerization of their matrix and polymer resin respectively. Indeed, the reactor 450 also comprises a means heating 455, however said heating means is advantageously configured to induce a temperature, which can be parameterized, between 200 ° C and 1500 ° C and adapted to induce depolymerization of the articles 10 and 20 to be recycled. Said heating can also be stepped.

In addition to making it possible to homogenize said articles 10, 20, to be recycled, the moving means 452 make it possible to facilitate the depolymerization of said articles within the reactor 450 by promoting their contacting.

Unlike known rotating drum systems, the latter can advantageously be used in the absence of a solid serving to promote heat transfer, which is particularly suitable for recycling composite articles.

[0141] Those skilled in the art will appreciate that the transport means used are specific to each embodiment of a recycling system in accordance with the invention and are thus suitable in particular for the use of a mixer-conveyor of Paddle Dryer type, a rotating drum or a twin-screw extruder. Likewise, it is expected that each of the embodiments of a system according to the invention can comprise suitable recovery means 405 of the residues or solids originating from the depolymerized articles to be recycled.

[0142] The invention will be further illustrated by the following examples. However, these examples should in no way be interpreted as limiting the scope of the present invention.

[Examples]

[0143] A] Preparation of Composites with Fibrous Reinforcement for Recycling [0144] Two compositions for a composite are prepared by dissolving RMMD beads consisting of copolymers of methyl methacrylate and of an acrylate. The acrylates will preferably be selected from methyl acrylates, butyl acrylates or ethyl acrylate.

This type of product is commercially available, for example from Altuglas in the Altuglas® BS range. PMMA Altuglas® or acrylic glass, is typically the material that meets the principle recycling and circularity, because it has the unique feature of being able to be depolymerized to methyl methacrylate and thus to be able to be reintroduced into the manufacturing process of new resins.

[0146] A composition for a composite is prepared from recycled polymers. For example, injected RMMD parts are used, such as car taillights, or else transparent plates which have been used in flat screens of televisions or computer screens. The parts are washed, dried and crushed before being dissolved in methyl methacrylate.

The preparations of various composites to be recycled C1, C2, C3 illustrated in the present invention are described below.

[0148] Example 1: Composite 1 (Cl)

In this example, RMMD beads are taken consisting of a copolymer of methyl acrylate and of methyl methacrylate (MAM). 100 g of beads are dissolved having an average particle size of 0.150 to 0.200 mm, a density of 0.7 g / ml, a Tg (for "glass temperature" according to English terminology, and corresponding to the glass transition temperature) at 107 ° C, in 900 g of methyl methacrylate, stabilized at 100 mg / kg with MEHQ (monoethyl ether of hydroquinone).

10 g of benzoyl peroxide are added to the dissolved mixture.

For the preparation of the composite for the test, a fiberglass fabric of 600 g / m ^{2 is used} . The fabric is manually impregnated with the PMMA / MAM solution. The solution is spread over the mold with a brush or roller, then the first layer of fabric is applied. A new layer of solution is then deposited which is distributed with a roller which also serves to eliminate the bubbles, and this operation is repeated until ten layers of fiberglass fabric have been deposited. Finally, an absorbent fabric is positioned which will facilitate demolding. The whole is placed in a plastic bag, which is placed under a partial vacuum (500 mBars - ie under vacuum). Then the whole is heated to 80 ° C for 4 hours, then allowed to cool to room temperature. [0152] Example 2: Composite 2 (C2)

Example 1 is repeated, but with 200 g of beads having a Tg of 110 ° C, an average particle size of 0.150 mm to 0.200 mm, a density of 0.7 g / ml, which are dissolved in 800 g of methyl methacrylate. 10 g of benzoyl peroxide are added to the mixture. The other operations are the same as for example 1.

[0154] Example 3: Composite 3 (C3)

In this example, 100 kg of RMMD plates obtained from the deconstruction of flat screens from televisions and computers are used. This product is therefore the result of the production of several RMMD manufacturers, with products spanning several years of production, and of varied origins but especially Asian given the nature of the deconstructed products. The selected plates are relatively clean, so as not to interfere with the test, the edges are cut to remove traces of possible contamination with adhesives, metals and other polymers. The plates are ground into pieces of the order of a centimeter, then washed and dried. The products are then dissolved in 900 kg of methyl methacrylate. Once the dissolution is complete, the solution is filtered to remove foreign bodies, and the polymer which would not be completely dissolved. Then 10 kg of benzoyl peroxide are added. And composites are produced as in Example 1, so as to consume all of the prepared solution.

[0156] The composites C1, C2, C3 are ground to reach maximum dimensions of 2 cm.

[0157] B] Configuration of depolymerization tests [0158] 1) Laboratory test equipment

The laboratory reactor is a batch reactor with a useful volume of 4.5 liters, containing a cast iron pot with a capacity of 1.2 liters and surmounted by a removable grid, and is heated electrically from the outside. . The vapors produced during pyrolysis are condensed by means of cold traps mounted in series. The first three traps are made of stainless steel and kept at 5 ° C, 0 ° C and -78 ° C respectively. The last trap is made of pyrex and is maintained at -78 ° C. Incondensable gases are directed outwards. Once the reactor has been loaded, it is purged under vacuum and / or under nitrogen, in order to remove the molecular oxygen from the enclosure. The tests are carried out under a vacuum of approximately 2.5 kPa.

[0160] 2) Pilot test equipment

The pilot tests are carried out in a cylindrical reactor 3 m long and 0.6 m in diameter which is heated from the outside to prevent any condensation in the installation. Heating for the depolymerization reaction is provided by heating soles supplied with a heat transfer fluid. The product to be depolymerized is placed on the heating floors, and flows through the installation. The set includes a power supply, a condensing unit, a solid residue discharge system, a vacuum pump. In continuous mode, the system allows a feed of 50 kg / h. Given the available quantities of composites, the tests were carried out initially in “Batch” mode. In this mode, the residue feed and withdrawal system are not used and the bed of products to be depolymerized is placed in rectangular containers on the heating plates.

The containers are filled with the product to be depolymerized, weighed and placed in the reactor. The condenser operates by spraying pyrolysis gases and is initially charged with water. The condensation liquid recirculates in the installation in order to maintain a continuous flow to the condenser. When the installation starts up, the air inside the reactor and the peripherals is evacuated using the vacuum pump. Then the reactor is heated to the desired temperature.

The pyrolysis in the pilot reactor is carried out at 380 ° C - 425 ° C, under a pressure of 2.1 kPa. The gases produced are rapidly cooled in two condensers of the spray column type in series. In the first condenser, the vapors are cooled using part of the liquid condensed at the bottom and cooled by water. During the tests the excess liquid which accumulates in the condensers is automatically discharged into a container attached to each condenser. The gases leaving the first condenser enter the second condenser where they are again brought into contact with the liquid condensed at the bottom of the condenser and cooled by water. The water condensed in this second condenser is separated by decantation from the recovered product.

When the pyrolysis is stopped, the heating is stopped, the pressure increased to atmospheric pressure by adding nitrogen to avoid any oxidation during the cooling of the solid.

After reaction, the mass of residual solid as well as the masses of the liquids collected are measured in order to carry out the mass balance.

[0166] 3) Sampling procedure:

The aqueous and organic phases collected in laboratory or pilot condensers are decanted, separated, and stored in plastic cans. Representative samples are collected after homogenization. Before analysis, the samples are stored cold and protected from light.

[0168] C] Depolymerization tests - laboratory test [0169] Example 4

200 g of Altuglas® HT121 resin granules, having a density of 1.19, are placed in the depolymerization reactor. The product is available from the company Altuglas.

[0171] Example 5

Example 4 is repeated with 200 g of Altuglas® HFI10 resin having a density of 1.15. The product is available from the company Altuglas.

A temperature rise ramp is applied to the reactor so that it reaches the set point temperature of 400 ° C. in 30 minutes. After 1 hour, the heating is stopped and the temperature is brought back to room temperature. The assembly is left under a stream of nitrogen at atmospheric pressure for 2 hours after the heating has been stopped. Once the temperature has returned to below 50 ° C., the traps can be removed and the masses of condensate weighed. The decomposition products of the polymer are recovered for analysis. A material balance is carried out. The mass of residual polymer is determined. The condensate trapped in the traps is weighed. The difference in mass is attributed to losses of light products due to cracking (methane, light hydrocarbons, CO, CO2-) also called non-condensable gases.

The condensate is analyzed by gas chromatography in particular.

[0176] Examples 6 and 7

The preceding examples are reproduced with 300 g of granules. [0178] Examples 8 and 9

200 g of composites of Examples 1 and 2, respectively Cl and C2, are used, ground to obtain flakes, the largest dimension of which is less than 2 cm. The ground composite is placed in the depolymerization oven, and the same protocol is applied as in the preceding examples.

[0180] Examples 10 and 11

The preceding examples are reproduced with 300 g of composite. [0182] Examples 12 to 19

Mechanical mixtures of composites and resin granules are carried out. The mixtures are placed in plastic bags, and homogenized by shaking, until no visual heterogeneity can be distinguished. The depolymerization protocol is then reproduced.

Good linearity of the decomposition products is observed for the same samples at 200 g and 300 g. In this range, the equipment is therefore not limiting in terms of heat and material transfer.

[0185] [Table 1]

[0186] Thus, the joint recycling of a first article to be recycled comprising a fibrous reinforcement (C1, C2) and of a second article to be recycled comprising a thermoplastic polymer resin, preferably (meth) acrylic, makes it possible to increase significantly the production yields of base monomer.

Thus, for the resin granule / composite mixtures, it is observed that the mass of depolymerized product (condensate) is higher than the simple addition of the masses resulting from the pure substances. It is also noted that the quantity of MAM recovered is higher than the simple addition of the masses of MAM obtained from the pure substances, for experiments carried out within the same time limits. The quality of the recovered product is therefore higher for higher productivity when mixing composites and PMMA of injection or extrusion grades. Thus, there is indeed an increase in the mass of base monomer recovered. using a process according to the invention in comparison with a mass of base monomer recovered with the techniques of the prior art

[0188] C] Depolymerization tests - pilot test [0189] Pilot Examples 20 to 23

[0190] In the metal containers, approximately 20 kg of crushed composite or of RMMD granules of the VM100 type available from Altuglas are placed, or a mechanical mixture of the two products. [0191] [Table 2]

In the pilot tests it is also possible to observe a significant gain in the production yield of base monomer. [0193] Thus, the present invention provides a simple and effective solution for an increase in the overall production yield of base monomer during recycling of a composite article, in particular in the case of a first article comprising a fibrous reinforcement. and exhibiting a low yield of monomer production. A method according to the invention makes it possible to carry out recycling of articles comprising a composite material whose carbon footprint is reduced and is therefore more respectful of the environment.

Claims

Resells! cations î. Process for recycling (100) a first article (10) to be recycled comprising a composite material based on fibrous reinforcement and a matrix of thermoplastic polymer, preferably (meth) acrylic, characterized in that said recycling process comprises the following steps: introduction (130) of the first article (10) into a system (1) suitable for recycling thermoplastic polymer, introduction (140), into the system (1) suitable for recycling thermoplastic polymer, of a second article (20) to be recycled comprising a thermoplastic polymer resin, preferably (meth) acrylic, and not comprising fiber reinforcement, heating (150) of the articles (10,20) to be recycled at a given temperature, in said system (1) suitable for recycling thermoplastic polymer, in order to depolymerize thermoplastic polymers, preferably (meth) acrylic, and form base monomers of said thermoplastic polymers, and recovery (160) of base monomers constituting said thermoplastic polymers.

2. Recycling process (100) according to claim 1, characterized in that it comprises a purification step (170) of the base monomers previously recovered.

3. A method of recycling (100) according to claims 1 or 2, characterized in that it comprises a step of removing (180) the solid elements produced during the step of heating the first and second articles (10, 20). ) to recycle.

4. Recycling method (100) according to any one of the preceding claims characterized in that the matrix of The thermoplastic polymer of the first article (10) is a matrix of poly (methyl methacrylate).

5. Recycling method (100) according to any one of the preceding claims characterized in that the first article (10) to be recycled and the second article (20) to be recycled are introduced at a mass ratio of between 0.1 and 1 , 5, preferably at a ratio between 0.1 and 0.5, more preferably at a ratio between 0.2 and 0.4.

6. Recycling process (100) according to any one of the preceding claims characterized in that the first article (10) to be recycled has a percentage by mass of fibrous reinforcement greater than 30%, preferably greater than 50%, moreover preferred greater than 70%.

7. Recycling process (100) according to any one of the preceding claims characterized in that the second article (20) is in the form of a syrup at room temperature and has a percentage by mass of thermoplastic monomer, preferably in monomer

(meth) acrylic equivalent greater than 80%, preferably greater than 90%, preferably greater than 95%.

8. Recycling method (100) according to any one of claims 1 to 6, characterized in that the second article (20) to be recycled has a percentage by mass of thermoplastic monomer, preferably of monomer.

(meth) acrylic equivalent, less than 95%, preferably less than 90%.

9. Recycling process (100) according to any one of claims 1 to 6, characterized in that the second article to be recycled has a percentage by mass of equivalent methyl methacrylate monomer of less than 95%, preferably less than 90%.

10. A recycling method (100) according to any one of the preceding claims, characterized in that the system (1) suitable for recycling thermoplastic polymer resin is selected from:

- a depolymerization system in an extruder and / or conveyor,

- a rotating drum depolymerization system, and

- a depolymerization system on heating plates.

11. A recycling method (100) according to any one of the preceding claims, characterized in that, during the heating step, the first and second articles (10, 20) to be recycled are heated to a temperature between 200 ° C and 1500 ° C, preferably at a temperature between 300 ° C and 600 ° C.

12. A recycling method (100) according to any one of the preceding claims, characterized in that it further comprises moderate heating (151) of the thermoplastic polymers, preferably (meth) acrylic, so as to liquefy them at least. in part.

13. Recycling method (100) according to any one of the preceding claims, characterized in that said method comprises a recovery (152) of the fibrous reinforcement of the first article (10) to be recycled, said recovery being carried out by one at the less of the following processes: centrifugation, draining, spinning, pressing, filtering, sieving and / or cycloning.

14. Recycling method (100) according to any one of the preceding claims, characterized in that said method comprises a preliminary sorting step (120).

15. Recycling method (100) according to any one of the preceding claims, characterized in that said method comprises a grinding step (110).

16. Recycling method (100) according to any one of the preceding claims, characterized in that the second article (20) to be recycled comprises at least 50% by mass of thermoplastic polymer, for example (meth) acrylic, more preferably. at least 60% by weight of thermoplastic polymer, for example (meth) acrylic and even more preferably at least 70% by weight of thermoplastic polymer, for example (meth) acrylic.

17. System (1) for recycling a first article (10) to be recycled comprising a composite material based on fibrous reinforcement and on a thermoplastic polymer matrix, preferably (meth) acrylic, said system (1) being characterized. in that it comprises: a conveying means (11) of said first article (10) to be recycled, a conveying means (21) of a second article (20) to be recycled comprising a thermoplastic polymer resin, of preferably (meth) acrylic, and not comprising fibrous reinforcement, and a reactor (50) suitable for heating the articles (10,20) to be recycled and for the depolymerization of thermoplastic polymers, preferably (meth) acrylic, and the formation of basic monomers of said thermoplastic polymers.

18. System (1) for recycling according to claim 17, characterized in that it comprises a second reactor (480) adapted for moderate heating of one of the articles (10, 20) to be recycled, preferably of the second article ( 20) to be recycled, said second reactor (480) comprising an opening (402) arranged to communicate fluidly with the first reactor (450).

19. System (1) for recycling according to claims 17 or 18, characterized in that it comprises a recovery means (60) of basic monomers constituting thermoplastic polymers.

20. System (1) for recycling according to any one of claims 17 to 19, characterized in that it comprises means for setting in motion (404, 452) said first and second articles to be recycled.

21. System (1) for recycling according to any one of claims 17 to 20, characterized in that the reactor (50) is an extruder or conveyor.

22. System (1) for recycling according to any one of claims 17 to 20, characterized in that the reactor (50) is a pyrolysis reactor.