Dissolution recycling of styrene-based polymers

Abstract

The invention relates to a method of processing a polymer composition comprising a polymer comprising repeating units of at least one aromatic vinyl monomer, such as polystyrene from post-consumer and / or post-industrial polymer waste, to at least partially remove additives, using at least one solvent component, wherein the RED value of the solvent component relative to the polymer, determined via Hansen Solubility Parameters at 25 °C (HSP), is in the range from 0.5 to <1. The invention also relates to a 0 polymer composition obtained by said method.

Description

[0001] INEOS Styrolution Group GmbH

[0002] Dissolution Recycling of Styrene-based Polymers

[0003] Description

[0004] The invention relates to a method of processing a polymer composition comprising a polymer comprising repeating units of at least one aromatic vinyl monomer, such as polystyrene from post-consumer and / or post-industrial polymer waste, to at least partially remove additives, using at least one solvent component, wherein the RED value of the solvent component relative to the polymer, determined via Hansen Solubility Parameters at 25 °C (HSP), is in the range from 0.5 to <1. The invention also relates to a polymer composition obtained by said processing method and to dissolution recycling of styrene polymers.

[0005] Polymer products are omnipresent and find applications in many aspects of everyday life, due to finely adjustable material properties and relatively low production costs. Due to the high technical potential and versatility of polymer products, polymeric articles are worldwide produced on a million tons scale. However, large production volumes are inevitably accompanied by the generation of large amounts of polymer waste, e.g. after the lifetime of the polymer product has expired.

[0006] Climate change, environmental pollution, population growth and resource dependency trigger the ecological and economic necessity of the transition from a linear to a circular economy. Since many years, intensive efforts are made to develop processes for the recovery of raw materials from plastics, such as post-consumer goods and post-industrial goods. Many efforts have not yet resulted in large-scale applications. However, a greater ecological awareness and a need for sustainable solutions have led to a growing interest in recycling of polymers.

[0007] One technical problem is that many styrene-containing polymer compositions contain flame retardants, for example foams composed of expanded polystyrene (EPS) which are used e.g. as insulating material in construction. Impact modified polystyrene (HIPS), as e.g. used in electrical housings, or other styrene (co)polymers can also be admixed with halogen-containing additives.

[0008] The use of flame retardants as additives is intended to reduce the risk of ignition and flame propagation in the event of afire. 1,2,5,6,9,10-hexabromocyclododecane (HBCD), and other brominated flame retardants have historically been used as flame retardants for EPS and HIPS. HBCD was included in the Stockholm Convention on Persistent Organic Pollutants in May 2013.

[0009] SL24 / 75188PC 13 January 2026INEOS Styrolution Group GmbH

[0010] 2

[0011] There is a global ban on the manufacture and use of HBCD as a flame retardant component. However, HBCD is still widespread in older buildings and electrical components. When these products are collected for disposal it is necessary to remove or treat the HBCD present therein. HBCD needs to be removed from the result of recycling processes (recyclate) in case the polymer component is to be reused for new products.

[0012] Brominated flame retardant containing products have hitherto typically been sent for thermal treatment, as there are no established processes to remove them from the recyclate to such an extent that the (legal) statutory values are not exceeded.

[0013] Dissolution recycling (also known as solvent based recycling) methods are one type of means for retrieving raw materials from polymer waste and essentially involve partial dissolution of polymer waste followed by separation of the dissolved components from insoluble components. Some known methods for dissolution recycling are described in the following.

[0014] Japanese publication JP-B 3752101 relates to a process for separating a thermoplastic resin composition into flame retardant and the thermoplastic resin. This process therefore covers a process for treating a flame retardant-containing thermoplastic resin composition, comprising the steps of: dispersing a thermoplastic styrenic polymer composition containing a bromine-based flame retardant in a solvent to dissolve at least a portion of the thermoplastic resin, successively removing at least a portion of the flame retardant of the thermoplastic resin from the solution in which the resin is dissolved and further removing at least a portion of the thermoplastic resin or of the flame retardant from the solution from which the flame retardant or the thermoplastic resin was removed.

[0015] US 6388050 relates to a process for treating a flame retardant-containing styrenic resin composition, comprising the steps of: a dissolving or dispersing step (a) in which a styrenic resin composition containing a bromide flame retardant is contacted with a single solvent to dissolve or disperse at least a portion of the flame retardant, a separating step (b) in which a solution or dispersion of the flame retardant according to step (a) is separated, a drying step (c) in which the styrenic resin composition from which the flame retardant is separated according to step (b) is dried.

[0016] US 7435772 describes the treatment of a resin composition containing a brominated flame retardant and an antimony-containing flame retardant with two solvents at a temperature between the glass transition temperature of the polymer and the boiling point of the respective solvent in two consecutive steps.

[0017] SL24 / 75188PCINEOS Styrolution Group GmbH

[0018] 3

[0019] CN-A 105237799 relates to a process for separating polybrominated diphenyl ethers from polymer compositions using a solvent.

[0020] US 8138232 describes a process for recycling a composition of at least two styrene-based polymers or copolymers in which the composition is mixed with a solvent and a precipitant is subsequently added.

[0021] JP-A 2016010906 relates to a process for removing HBCD from a foamed polystyrene composition comprising two solvents, one which dissolves HBCD but not polystyrene and a second which dissolves polystyrene.

[0022] JP-A 2000290424 relates to a process for reusing a thermoplastic resin composition containing a bromine-based flame retardant, wherein the resin composition is contacted with water or an alcohol to accelerate that debromination reaction of the flame retardant to remove the bromine. This process for reusing the thermoplastic resin composition which contains the bromide-based flame retardant additionally comprises contacting the resin composition with a metal hydroxide, a metal carbonate or octyl alcohol to produce the corresponding bromide salts or octyl bromide and subsequently eliminating the bromides produced or the octyl bromide produced from the resin.

[0023] EP-A 1311599 and US 2004 / 229965 disclose methods for separating and recovering target polymers and additives from a polymer-containing material, by dissolving the material in a first solvent and precipitating the target polymer using a second solvent. WO 2024 / 038130 proposes a method of recycling at least one target polymer from plastic waste containing at least one contaminant, comprising a step of selectively dissolving the target polymer.

[0024] EP-A 1888677 describes a method for recycling plastics containing at least two styrene-based polymers, by dissolving the plastics in a solvent, precipitating one of the polymers using a precipitation agent, and separating the precipitated products from the dissolved products. EP-A 1899129 is directed at a method for separating differently additivated styrene-based polymers by density, using a liquid or gaseous separation medium. EP-A 3016998 describes a method for enriching a polymer from polymer waste, comprising the mixing of the waste with a solvent containing a thermo-stabilizer, such that a solution of polymer and an insoluble portion are obtained, separation of the solution from the insoluble portion, and separation of the solvent from the polymer.

[0025] EP-A 2513212 proposes a process for recycling polymer waste containing a target polymer and a contaminant, wherein the waste is treated with a swelling agent, to obtain a polymer gel, and removing the contaminants not dissolved in the gel.

[0026] SL24 / 75188PCINEOS Styrolution Group GmbH

[0027] 4

[0028] EP-A 1907462 discloses a process for the recovery of polystyrene from waste material containing expanded polystyrene, comprising a volume reduction of expanded polystyrene by dissolution in a solvent, separation of the insoluble components, precipitation of the polystyrene using an anti-solvent, and further processing of the polystyrene. EP-A 3870640 relates to a process for recycling polymer waste, comprising dissolving the waste in a solvent to obtain a mixture of liquid and solids, heating the mixture under acidic conditions, cooling the mixture to obtain a supernatant comprising polymer in solution and a solid waste residue, separating the supernatant from the residue, and precipitating the polymer from the supernatant.

[0029] CN-A 103709436 is directed at a method for separating ABS and PS from waste plastic, comprising dissolving the waste in a solvent to obtain a plastic solution and filtering the plastic solution. CN-A 109400947 teaches a method for treating a foamed material of a waste polystyrene resin, using dissolution of polystyrene in citrus oil. CN-A 106750511 describes a method for recovering ABS from a composite plastic, comprising steps of cleaning composite plastic with water, dissolving the composite plastic in a complex mixture of 7 solvents, heating the mixture at high pressures, filtering the mixture, ultrasonic treatment of the mixture and further steps, to obtain ABS particles.

[0030] EP-A 3317337 discloses a method for purifying a reclaimed polymer comprising the steps of contacting the reclaimed polymer at a temperature from 80 to 220 °C and a pressure from 1.03 MPa to 103.42 MPa with a first fluid solvent having a boiling point less than 70 °C, to produce extracted reclaimed polymer, dissolving the extracted reclaimed polymer in a solvent at 90 to 220 °C and a pressure of 2.41 MPa to 137.9 MPa, to produce a polymer solution, and separating the polymer from said polymer solution. US 2020 / 0181354 teaches a method for separating a plastic-based complex waste into a floating plastic component, a dissolved plastic component and a sinking component using a separating agent and collecting each component separately.

[0031] Further disclosures of attempts to recycle styrene-polymer containing materials using solvents are disclosed in KR-B 100756313, KR-B 102149904, US 2007 / 0054106, US 2024 / 0287274.

[0032] The prior art mainly focuses on methods of solvent-based separation of polymers from additives or contaminants, wherein a solvent is selected that is optimized (i.e. as good as possible) for dissolving the target polymer, which is typically the case if the solvent has a relative energy difference (RED), determined via Hansen Solubility Parameters at 25 °C (HSP), between 0 and 0.5.

[0033] SL24 / 75188PCINEOS Styrolution Group GmbH

[0034] 5

[0035] However, it now has been surprisingly found that the separation of vinylaromatic mono-mer-containing polymers (i.e. styrene (co)polymers) from additives or contaminants can be substantially improved and / or facilitated, if certain separation steps are carried out and a solvent is selected, in which the solubility of the target polymer is sub-optimal.

[0036] One aspect of the present invention is a method of processing a polymer composition P, comprising the steps:

[0037] a) mixing a polymer composition P, preferably comprising or consisting of post-consumer and / or post-industrial waste, comprising

[0038] A) a polymer A comprising repeating units of at least one aromatic vinyl monomer A1 , preferably general purpose polystyrene and / or high impact polystyrene; and

[0039] B) at least one additive B, preferably a colorant and / or flame retardant and / or stabilizer and / or processing agent, more preferably a flame retardant, more preferably a halogenated flame retardant;

[0040] with a solvent component S1, to obtain a mixture M;

[0041] b) subjecting the mixture M to conditions allowing separation of a fraction F1 comprising the polymer A from at least one fraction F2 comprising at least one additive B; and

[0042] c) recovering a polymer composition P1 comprising the polymer A from fraction F1, wherein in the polymer composition P1 , the relative weight content of components that are not polymers comprising repeating units of aromatic vinyl monomer A1 is reduced by at least 50%, preferably at least 70% by weight, more preferably by at least 80% by weight, more preferably by at least 90% by weight, more preferably by at least 95% by weight, compared to the polymer composition P;

[0043] wherein the RED value of the solvent component S1 relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is in the range from 0.5 to <1; and wherein step b) comprises the following steps:

[0044] b1) setting the temperature of the mixture M to a temperature Ti, which is equal to or greater than the upper critical solution temperature (LICST) of the polymer A in the solvent component S1 ; and

[0045] b2) removing at least a portion of at least one additive B from the mixture M at the temperature Ti using at least one solid sorbent material SM or at least one solvent component S2, to obtain a fraction F1 comprising the polymer A and the solvent component S1 and a fraction F2 comprising the additive B and the solid sorbent material SM or the solvent component S2;

[0046] wherein the solvent component S2 fulfils the following criteria (1), (2) and (3):

[0047] (1) the RED value of the solvent component S2 relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is greater than 1.0;

[0048] (2) the solubility of the additive B in the solvent component S2 at the temperature Ti is greater than its solubility in solvent component S1 ; and

[0049] SL24 / 75188PCINEOS Styrolution Group GmbH

[0050] 6

[0051] (3) a mixture of the solvent component S1 and the solvent component S2 at the temperature Ti is heterogeneous, when the amount of the solvent component S2 exceeds 10% by weight, preferably exceeds 5% by weight, more preferably exceeds 1% by weight, more preferably exceeds 0.1 % by weight, based on the total weight of the mixture of the solvent component S1 and the solvent component S2.

[0052] In general, the principle for solubility is “like dissolves like”. For the selection of solvents in the coatings industry several solubility parameter systems were developed to give guidelines. One of the main applied parameter sets are the Hansen solubility parameters (HSP). Hansen parameters are a known method for estimating the solubility and / or miscibility of different compounds and are based on the possibility to separate the energy of vaporization (cohesive energy) of a liquid into several parts from dispersion forces (atomic), permanent dipole-permanent dipole forces (molecular), and hydrogen bonding (molecular). General principles regarding Hansen Solubility Parameters are described, e.g. in “Hansen Solubility Parameters: A User’s Handbook” (C. M. Hansen, 2007, CEC Press, 2. edition).

[0053] The relative energy difference (RED value) of a solvent component S1 relative to the polymer A is determined from the Hansen solubility parameters of the solvent component S1 and the Hansen solubility parameters of the polymer A at 25 °C, and is defined by the equation:

[0054] Ra

[0055] RED =

[0056] RQ

[0057] where Rais the HSP distance between the solvent component S1 and Ro is the radius of the HSP sphere radius of the polymer A. In this equation, the HSP distance Rais determined by the following equation:

[0058]

[0059] < < <

[0060] where 6DI, 6PI and 6HI are Hansen Solubility Parameters (HSP) for the dispersive, dipolar and hydrogen bonding forces, respectively, of one molecule (e.g. the solvent component S1), and 5D2, 6P2 and 5H2 are the respective parameters of the other molecule (e.g. the at least one polymer A).

[0061] The values of the individual parameters can be found in suitable databases, or determined as described in “Hansen Solubility Parameters: A User’s Handbook” (C. M. Hansen, 2007, CEC Press, 2. edition).

[0062] SL24 / 75188PCINEOS Styrolution Group GmbH

[0063] 7

[0064] For example, the HSP value of a polymer can be determined by dissolving polymers in a large range of solvents with well-known HSP parameters, and evaluating by the HSP sphere method as described in “Hansen Solubility Parameters: A User’s Handbook” (C. M. Hansen, 2007, CEC Press, 2. edition). The HSP values of a mixture of at least two solvents can be determined by calculating the volume average HSP parameters from known HSP values of the individual solvents.

[0065] For determination of the HSP sphere, 10 g / L samples of a polymer in the respective solvents can be used. Solvents, in which complete dissolution of the polymer for non-cross-linked polymers or a high degree of swelling (dissolved appearance with few gellike particles) for cross-linked polymers within 24 h is observed (e.g. by visual evaluation), are rated as suitable solvents. All other solvents are rated as unsuitable solvents. For construction of the HSP sphere, the genetic fitting algorithms of the software “Hansen Solubility Parameters in Practice” (HSPiP, published by Hansen-Solubility.com) developed by Dr. Hansen's group, can be used. The radius of the HSP sphere determined this way for the polymer A at 25 °C is Ro, and is used in the calculation of the relative energy difference (RED value) of a specific solvent component S1 relative to the polymer A.

[0066] Preferably, the solvents for determination of the HSP sphere for the at least one polymer A are selected from the solvent database provided in the software HSPiP. Preferably, at least 50 different solvents or solvent mixtures are used for the determination of the HSP sphere of the at least one polymer A.

[0067] Since in the polymer composition P used in the method of the present invention, the polymer A is part of a mixture with other components such as at least one additive B, the HSP sphere of the polymer A and the RED values relative to the polymer A are determined fora model polymer, which is synthesized to have a monomer composition (measured, e.g. by1H NMR spectroscopy) and weight-average molecular weight (measured by gel permeation chromatography calibrated to polystyrene standards) that correspond to those of the polymer A in the polymer composition P.

[0068] The polymer composition P used in the method of the present invention is not particularly limited, and may be any polymer composition comprising a polymer A comprising repeating units of at least one aromatic vinyl monomer A1 and at least one additive B. Preferably the polymer composition P comprises or consists of post-consumer and / or postindustrial waste.

[0069] SL24 / 75188PCINEOS Styrolution Group GmbH

[0070] 8

[0071] Optionally, the polymer composition P may comprise, apart from the polymer A and the at least one additive B, further components, such as polymers that do not comprise repeating units of at least one aromatic vinyl monomer A1 , and contaminants including but not limited to dirt, moisture, paper, metals, food residues and other organic or inorganic residues.

[0072] The polymer A may be any type of polymer comprising repeating units of at least one aromatic vinyl monomer A1. For example, the polymer A may be a homopolymer of an one aromatic vinyl monomer A1 , a copolymer of multiple vinylaromatic monomers A1 , or a copolymer of at least one aromatic vinyl monomer A1 and at least one monomer A2 that is not vinylaromatic, or a graft copolymer of the at least one aromatic vinyl monomer A1 and optionally at least one monomer A2 with a particulate substrate, e.g. a rubber, such as conjugated diene-based rubber or a (meth)acrylate-based rubber.

[0073] The vinylaromatic monomer A1 is not particularly limited and may be selected, e.g. from the group consisting of styrene, a-methyl styrene, aromatic-ring-substituted styrenes, including m-, p-, and / or o- substituted styrenes, halogenated styrene derivatives, etc. Preferably, the vinylaromatic monomer A1 is selected from the group consisting of styrene, a-methyl styrene, p-methyl styrene, p-tert-butyl styrene, dimethyl styrenes, aryl-bromin-ated or -chlorinated styrenes and combinations thereof. More preferably, the vinylaromatic monomer A1 is selected from styrene and a-methyl styrene. Even more preferably, the vinylaromatic monomer A1 comprises or consists of styrene.

[0074] Where the polymer A is a copolymer of the vinylaromatic monomer A1 with at least one monomer A2, it may be any type of copolymer, such as a random copolymer or a block copolymer. For example, the polymer A may comprise:

[0075] A1) 40 to 100% by weight, preferably 50 to 99% by weight, more preferably 60 to 98% by weight, based on the total weight of polymer A, of repeating units of at least one aromatic vinyl monomer A1, preferably styrene, alpha-methyl styrene, p-methyl styrene, tert-butyl styrene, dimethyl styrene, aryl-halogenated styrene or mixtures thereof, more preferably styrene and / or alpha-methylstyrene, more preferably styrene;

[0076] A2) 0 to 15%, preferably 0 to 10% by weight, more preferably 0 to 5% by weight, based on the total weight of the polymer A, of repeating units of at least one (meth)acrylonitrile and / or (meth)acrylate monomer A2;

[0077] A3) 0 to 60% by weight, preferably 1 to 50% by weight, more preferably 2 to 40% by weight, based on the total weight of polymer A, of repeating units of at least one conjugated diene monomer A3, preferably butadiene or isoprene, more preferably butadiene; and

[0078] SL24 / 75188PCINEOS Styrolution Group GmbH

[0079] 9

[0080] A4) 0 to 30% by weight, preferably 0 to 15% by weight, more preferably 0 to 5% by weight, based on the total weight of the polymer A, of units of cross-linking agents and / or further monomers copolymerizable with A1, A2 and A3.

[0081] For example, the polymer A may comprise repeating units of the at least one aromatic vinyl monomer A1 and optionally of at least one (meth)acrylonitrile and / or (meth)acrylate monomer A2 grafted to at least one rubbery core, preferably at least one rubbery core comprising repeating units of at least one conjugated diene monomer A3 and optionally at least one monomer A1 and / or A2, and optionally cross-linking agents and / or further monomers copolymerizable with A3.

[0082] Preferably, the polymer A is selected from polystyrenes. Polystyrenes are preferably selected from standard polystyrenes (also referred to as general purpose polystyrene GPPS), which comprise mainly the at least one vinylaromatic monomer A1, and high-impact polystyrenes (HIPS), which further comprise an elastomeric material. Furthermore, the polymer A may be a mixture of high-impact polystyrenes (HIPS) and standard polystyrenes (GPPS).

[0083] In a preferred embodiment the polystyrene is selected from high-impact polystyrenes (HIPS). The preparation, structure, and properties of said polystyrenes are generally described in detail in the literature, e.g. by Echte, Haaf, Hambrecht in Angew. Chem. Int. Ed. Engl. 1981, 20, 344-361; and in Kunststoffhandbuch, edited by Vieweg and Daumil-ler, Vol. 4 “Polystyrol”, Carl-Hanser-Verlag Munich (1996).

[0084] As used herein, the term "high impact polystyrene" or "HIPS" refers to rubber modified polystyrene, comprising a polystyrene as matrix material and at least one impact modifying polymer described in the following as elastomeric material. For example HIPS can be prepared by adding an polybutadiene rubber, or other elastomeric materials, into styrene monomer during polymerization, so it can become chemically bonded to the polystyrene, forming a graft copolymer which helps to incorporate the elastomeric material into the final resin composition. As used herein, the term "elastomeric material" refers to a material that deforms when stress is applied and returns to its original configuration when the stress is removed.

[0085] Typically, the elastomeric material that can be used to make high impact polystyrene (HIPS) can be one or more impact modifying polymer comprising monomer residues from styrene, 1 ,3-butadiene, isoprene, acrylonitrile, ethylene, C3 to C12 alpha olefins, and combinations thereof.

[0086] SL24 / 75188PCINEOS Styrolution Group GmbH

[0087] 10

[0088] As used herein, the terms "monomer unit", “repeating unit” and “repeating unit of at least one monomer” may be used interchangeably and refer to the monomeric repeating unit in a polymer derived from polymerization of the specific monomers which contain a polymerizable unsaturated group. Accordingly, “derived”, implies in this context derivati-zation that occurs due to polymerization. As used herein, the term "polymer" is meant to encompass homopolymers, copolymers and graft copolymers.

[0089] In some embodiments of the invention, the impact modifying polymer can be a rubbery polymer containing an ethylenic unsaturation. In some cases, the impact modifying polymer can be a co- or homopolymer of one or more C4 to Ge conjugated diolefins, such as polybutadiene.

[0090] In some preferred embodiments, the polymer A is selected from high-impact polystyrenes comprising a polystyrene and at least one impact modifying polymer such as butadiene rubbers (BR) and styrene-butadiene rubbers (SBR).

[0091] The butadiene rubber preferably comprises a medium or high content of cis-configured butadiene repeating units. Typically, the high content refers to at least 90 % by weight, in some cases more than about 93 % by weight, based on the polybutadiene, of repeating units in the cis-configuration. In many instances, the medium content refers to a content of cis-configured butadiene repeating units from about 30 to about 50 % by weight, in some cases from about 35 to about 45 % by weight, based on the polybutadiene rubber.

[0092] Suitable butadiene rubbers that can be used in the invention include those commercially available from various sources; for example Buna CB 550 available from Arlanxeo Corporation (Pittsburgh, PA); PB 5800-Schkopau available from the Trinseo LLC (Berwyn, PA); and Diene® 55AC15 and Diene® 70AC15 available from Firestone Polymers LLC (Akron, OH).

[0093] Furthermore, the impact modifying rubber may be selected from structurally modified specific butadiene rubbers, for example those having a fraction of 1,4-cis and / or 1,4-trans linkages relative to conventional rubbers.

[0094] Furthermore, instead of butadiene rubber, or in combination therewith, it is also possible to use other diene rubbers and / or elastomers, such as ethylene-propylene-diene rubbers (EPDM rubber), hydrogenated diene rubbers, and / or silicone rubbers, as impact modifying elastomeric material.

[0095] SL24 / 75188PCINEOS Styrolution Group GmbH

[0096] 11

[0097] The polymer A can be prepared, e.g., by polymerizing one or more of the afore-mentioned vinylaromatic monomers A1, optionally in the presence of at least one (methacrylonitrile and / or (meth)acrylate monomer A2, and the elastomeric material, wherein preferably the polymerization reaction is initiated thermally and / or by a radical initiator. Radical initiators are known in the art and are not particularly limited. For example, the radical initiator may be 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, preferably in an amount of 50 to 500 ppm by weight, more preferably 100 to 250 ppm by weight, based on the total reaction mixture,.

[0098] Thermal initiation may be induced by subjecting a reaction mixture comprising one or more of the aforementioned monomers, optionally in the presence of the elastomeric material, to increased temperatures, e.g. to a temperature between 100°C and 180°C, preferably 110 to 150°C.

[0099] For example, methods for preparation of polymers A are disclosed in US 2011 / 0054123, US 5,543,461 (see col. 5, I. 3 to 42), US 5,861,455 (see col. 3, I. 42 to col. 4, I. 17) and US 6,613,837 (see col. 3, 1.55 to col. 4, I. 23), the relevant portions of which are herein incorporated by reference.

[0100] Preferably, the polymer A is a general purpose polystyrene and / or a high-impact polystyrene which comprises 80 to 99 % by weight, preferably 85 to 98 % by weight of a vinylaromatic matrix, preferably polystyrene, and 1 to 20 % by weight, preferably 2 to 15 % by weight, of at least one impact modifying polymer, preferably a polybutadiene and / or a styrene-butadiene copolymer.

[0101] The impact modifying elastomer, if present, is typically present in the form of particles, often having a volume-average (Dso median) particle size of at least about 0.25 pm, in some cases at least about 0.5 pm and in other cases at least about 1 pm. Preferably, the volume average particle size of the particles of the impact modifying elastomer can be up to about 12 pm, in some cases up to about 11 pm and in other cases up to about 10 pm. Often, the volume average particle size of the particles of the impact modifying elastomer can be in the range of from 1 pm to 10 pm, e.g. 2, 4 or 7 pm. The volume average particle size of the particles of the impact modifying elastomer can be any value or range between any of the values recited above.

[0102] The volume average particle size of the impact modifying elastomer is typically measured by analyzing the distributions obtained from laser diffraction through a dispersion of the particles in a solvent, such as methyl ethyl ketone or ethyl acetate. Instruments suitable for this measurement include Horiba's Model LA-920 or Beckman Coulter's LS 13320.

[0103] SL24 / 75188PCINEOS Styrolution Group GmbH

[0104] 12

[0105] Suitable general purpose polystyrenes (GPPS) are prepared by the method of anionic or radical polymerization of styrene or styrene derivatives mentioned above. Preferably, GPPS is prepared by polymerization of styrene or a mixture of styrene with any other copolymerizable monomer.

[0106] Preferably, GPPS is prepared by polymerization of styrene or a mixture of styrene and one or more monomers selected from p-methyl styrene, tertiary butyl styrene, dimethyl styrene, aryl-brominated or -chlorinated derivatives thereof and combinations thereof. Generally, the non-uniformity of the polymer, which may be influenced by the polymerization method, is of minor importance in the context of the inveniton.

[0107] Preferably, the weight average molecular weight (Mw) of the polymer A ranges from 50,000 to 500,000 g / mol, more preferably from 120,000 to 250,000 g / mol, more preferably from 130,000 to 240,000 g / mol. Typically molecular weight values are determined using gel permeation chromatography (GPC) calibrated to polystyrene standards. Unless otherwise indicated, the molecular weight values indicated herein are weight average molecular weights (Mw).

[0108] The at least one additive B in the polymer composition P used in the method of the invention is not particularly limited and may be any conventional additive used in vinylar-omatic polymers. For example, the at least one additive B may comprise colorants (that may be soluble or insoluble in the polymer A), flame retardants, synergists for flame retardants, light stabilizers, UV absorbers, antioxidants, stabilizers for improving thermal stability, stabilizers for enhancing hydrolysis resistance and chemical resistance, antithermal decomposition agents, lubricants and mold release agents, fibrous and particulate fillers, reinforcing agents, nucleating agents, metal scavengers, antistatic agents, matting agents, processing aids and plasticizers.

[0109] Examples of UV absorbers include substituted benzotriazoles, substituted benzophenones, substituted triazines, oxalanilides, substituted resorcinols, salicylates and cyanoacrylates, such as 2-(2-hydroxyphenyl) benzotriazoles, 2-hydroxy-benzophenones, hydroxyphenyl-s-triazines and oxalanilides. Furthermore, secondary stabilizers such as the commercially available Irgafos® 168 (BASF SE) may be used. The amount of these UV absorbers, if present, is preferably from 0.01 to 2% by weight, preferably 0.05 to 0.5% by weight, more preferably from 0.06 to 0.4% by weight, more preferably from 0.08 to 0.3% by weight, more preferably from 0.1 to 0.25% by weight based on the total weight of the polymer composition P.

[0110] SL24 / 75188PCINEOS Styrolution Group GmbH

[0111] 13

[0112] Examples of light stabilizers include hindered amine light stabilizers (HALS), such as derivatives of 2,2,6, 6-tetramethylpiperidine, preferably derivatives of 2,2,6, 6-tetramethyl-4-piperidyl-substituted organic compounds. Suitable hindered amine light stabilizers are, e.g., bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate (Tinuvin® 770 by BASF SE); bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (Tinuvin® 765 by BASF SE); N,N’-bis-formyl-N,N’-bis-(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylendiamine (llvinul® 4050 H by BASF SE); N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)isophthalamide (Nylostab® S-EED® by Clariant); 2,2,6,6-tetramethyl-4-piperidinyl stearate (Cyasorb® UV-3853 by Solvay); and sterically hindered amine with the CAS Registry number 71878-19-8 (Chimassorb® 944 by BASF SE).

[0113] If present, the hindered amine light stabilizer is preferably a derivative of bis(2, 2,6,6-tetramethyl-4-piperidyl)dicarboxylic acid diesters, in particular bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate. The amount of these light stabilizers, if present, is preferably from 0.01 to 0.5% by weight, more preferably 0.05 to 0.45% by weight, more preferably from 0.06 to 0.4% by weight, more preferably from 0.08 to 0.3% by weight, more preferably from 0.1 to 0.25% by weight, based on the total weight of the polymer composition P.

[0114] Examples of antioxidants include compounds selected from monophosphite-based antioxidants, diphosphite-based antioxidants and sterically hindered phenolic antioxidants. If one or more antioxidants are present, they are preferably selected from monophos-phite-based antioxidants, such as trisubstituted monophosphite derivatives, diphosphite-based antioxidants, such as substituted pentaerythrirol diphosphite derivatives and sterically hindered phenolic antioxidants, such as 2,6-di-tertbutylphenolic derivatives.

[0115] Often, the at least one antioxidant will comprise at least one sterically hindered phenolic antioxidant. The phenolic antioxidant component is preferably selected from sterically hindered phenolic antioxidants of the general formula (I) and mixtures thereof:

[0116]

[0117] SL24 / 75188PCINEOS Styrolution Group GmbH

[0118] 14

[0119] wherein R1 to R5 independently represent hydrogen atoms or alkyl groups having 1 to 70 carbon atoms, wherein the hydrocarbon group optionally comprises at least one heteroatom selected from O and S, and wherein at least one of the substituents R1 and R5 represents a hydrocarbon group having at least 3 carbon atoms. More preferably, at least one of the substituents R1 and R5 represents a hydrocarbon group having 3 to 6 carbon atoms, preferably an iso-propyl group, a sec-butyl group, a tert-butyl group, a neo-pentyl group and / or a cyclohexyl group.

[0120] In some embodiments, at least one of the substituents R2, R3 and R4 represent a hydrogen atom. In some embodiments, at least one of the substituents R2, R3 and R4 represent a hydrocarbon group having at least 1 carbon atom. In some embodiments, at least one of the substituents R1 and R5 represents a tert-butyl group; at least two of the substituents R2, R3 and R4 represent a hydrogen atom; and one of the substituents R2, R3 and R4 represents a hydrocarbon group having at least 1 carbon atom.

[0121] In some embodiments, the at least one sterically hindered phenolic antioxidant B is selected from compounds of the general formula (l-a):

[0122]

[0123] (l-a)

[0124] wherein R3 represents a hydrocarbon group having 1 to 70 carbon atoms, wherein the hydrocarbon group optionally comprises at least one heteroatom, selected from O and S; and R2, R4, and R5 independently represent hydrogen atoms or alkyl groups having 1 to 4 carbon atoms, and wherein at least one of the substituents R2, R3, and R4 is not hydrogen.

[0125] In some embodiments, the at least one sterically hindered phenolic antioxidant B is selected from octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (CAS-No.: 2082-79-3, Irganox® 1076), 2,6-di-tert-butyl-p-cresol (CAS-No. 87-97-8, Kerobit® TBK), 2-(1,1 -dimethylethyl)-6-[(3-(1 , 1 -dimethylethyl)-2-hydroxy-5-methylphenyl]methyl-4-methylphenyl acrylate (CAS-No. 61167-58-6, Irganox® 3052), and mixtures thereof.

[0126] Further examples of compounds that may be used include oxygen radical scavengers such as pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (CAS-

[0127] SL24 / 75188PCINEOS Styrolution Group GmbH

[0128] 15

[0129] No. 6683-19-8, Irganox® 1010, BASF SE), tetrakis[methylene-3-(3,5-di-tert-butyl-4-hy-droxyphenyl)-propionate]methane (CAS-No. 6683-19-8, Songnox® 1010, Songwon), 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phe (CAS-No. 991-84-4, Irganox® 565, BASF SE) and blends thereof, carbon radical scavengers such as 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate (CAS-No.

[0130] 123968-25-2, Sumilizer® GS, Sumitomo), 2-(1 , 1 -dimethylethyl)-6-[[3-(1 , 1 -di-methylethyl)-2-hydroxy-5-methylphenyl]-methyl]-4-methylphenylacrylat (CAS-No.

[0131] 61167-58-6, Sumilizer® GM, Sumitomo) and blends thereof.

[0132] In one embodiment of the invention, the antioxidant comprises or consists of a 2,6-di-tert-butyl-p-cresol (CAS-No. 87-97-8), a hindered phenolic antioxidant of following formula (l-b):

[0133]

[0134] (l-b)

[0135] In some embodiments, antioxidants are one or more compounds selected from tri-phenyl substituted monophosphite derivatives, diphenyl substituted pentaerythritol diphosphite derivatives and mono-substituted 2,6-di-tert-butylphenolic derivatives. More preferably, the antioxidants are one or more of tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite and octa-decyl-3-[3,5-di-tert-butyl-4-hydroxy-phenyl]propionate.

[0136] The amount of antioxidants, if present, is preferably from 0.01 to 2% by weight, more preferably from 0.02 to 0.5% by weight, more preferably from 0.03 to 0.2% by weight, more preferably from 0.05 to 0.15% by weight, based on the total weight of the polymer composition P.

[0137] Examples of suitable antistatic agents include amine derivatives such as N,N-bis(hydrox-yalkyl)alkylamines or -alkyleneamines, polyethylene glycol esters, copolymers of ethylene oxide glycol and propylene oxide glycol (in particular two-block or three-block copolymers of ethylene oxide blocks and propylene oxide blocks), and glycerol mono- and distearates, and mixtures thereof.

[0138] SL24 / 75188PCINEOS Styrolution Group GmbH

[0139] 16

[0140] Examples of suitable matting agents include not only inorganic substances such as talc, glass beads or metal carbonates (for example MgCOa, CaCCh) but also polymer particles, in particular spherical particles having diameters D50 greater than 1 pm, based on, for example, methyl methacrylate, styrene compounds, acrylonitrile or mixtures thereof. It is further also possible to use polymers comprising copolymerized acidic and / or basic monomers.

[0141] Examples of fillers include carbon or glass fibers in the form of glass fabrics, glass mats, or filament glass rovings, chopped glass, glass beads, and wollastonite, amorphous silica, magnesium carbonate, powdered quartz, mica, bentonites, talc, feldspar, calcium silicates, such as wollastonite, and kaolin.

[0142] Examples of lubricants and demolding agents include long-chain fatty acids, such as stearic acid or behenic acid, salts of fatty acids (e.g. calcium stearate or zinc stearate), esters of fatty acids (e.g. stearyl stearate or pentaerythrityl tetrastearate), amide derivatives of fatty acids (e.g. ethylenebisstearylamide, erucamide, Acrawax®), phosphates (such as tricalcium phosphate), hydrocarbon waxes, such as microcrystalline waxes and paraffin waxes (e.g. Besquare®), and fumed silica (e.g. Aerosil®). Typically fatty acids are carboxylic acids having a linear or branched, saturated or unsaturated Ci to C45, preferably C5 to C25 alkyl chain.

[0143] Examples or colorants include dyes and pigments such as, for example, carbon black, titanium dioxide or transition-metal based pigments.

[0144] Examples of flame retardants include

[0145] hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA), triphenyl phosphate, decabromodiphenyl ethane (DBDPE) and polybrominated styrene-butadiene copolymer (PolyFR under trade name FR-122P™).

[0146] This selection covers both brominated flame retardants (BFRs), phosphated flame retardants (PFRs) and polymeric flame retardants.

[0147] The corresponding chemical structures are as follows:

[0148] SL24 / 75188PCINEOS Styrolution Group GmbH

[0149] 17

[0150]

[0151] Preferably, the at least one additive B is selected from the group consisting of colorants, flame retardants, stabilizers and processing agents, more preferbaly from flame retardants, more preferably from halogenated flame retardants. More preferably, the at least one additive B comprises one or more of HBCD, TBBPA, DBDPE, TPHP and FR-122P, more preferably, the at least one additive B comprises HBCD and optionally one or more further flame retardants selected from TBBPA, DBDPE, TPHP and FR-122P. In some embodiments, the at least one additive B comprises at least HBCD and FR-122P.

[0152] In some embodiments, the polymer composition P may contain polymers that do not contain repeating units of aromatic vinyl monomers. Exemplary further polymers include, e.g. homo- and co-polymers of monomers A2, A3 and / or A4 as defined above, with each other and other monomers that are not vinylaromatic; polyesters; polycarbonates; polyamides; polyethers; polyurethanes; phenyl formaldehyde resins; compatibilizing polymers; and polyester modified polysiloxanes. Preferably, the polymer composition P does not contain any further polymeric components apart from the polymer A described above and optionally elastomeric materials lacking vinylaromatic monomers. More preferably, the polymer composition P does not contain any further polymeric components apart from the polymer A.

[0153] Preferably, the polymer composition P comprises:

[0154] SL24 / 75188PCINEOS Styrolution Group GmbH

[0155] 18

[0156] A) 60 to 99.9% by weight, based on the total weight of the polymer composition P, of one or more polymers A, preferably comprising general purpose poly-styrene and / or high impact polystyrene;

[0157] B) 0.1 to 30% by weight, based on the total weight of the polymer composition P, of one or more additives B, preferably comprising at least one flame retardant and optionally one or more pigments, dyes, fillers, plasticizers, stabilizers and lubricants;

[0158] C) 0 to 30% by weight, based on the total weight of the polymer composition P, of one or more polymers C not containing any repeating units of at least one aromatic vinyl monomer A1; and

[0159] D) 0 to 30% by weight of contaminants such as organic residues, dirt, metals, paper and moisture.

[0160] In step a), the polymer composition P is mixed with a solvent component S1 to obtain a mixture M. Depending on chemical composition of the polymer composition P e.g. depending on the polymer A and the at least one additive B) and the solvent component S1 , the mixture M obtained from mixing the polymer composition P with the solvent component S1 may be homogeneous or heterogeneous.

[0161] Mixing may be carried out by any means known in the art for this purpose. For example, mixing can by carried out by immersing the polymer composition P, such as post-consumer waste or post-industrial waste, in the solvent component S1 , and agitation or passive diffusion, preferably by stirring or shaking, more preferably by stirring.

[0162] Preferably, the polymer composition P and the solvent component S1 are mixed in a weight ratio of P:S1 from 1:99 to 40:60, preferably from 2:98 to 30:70, more preferably from 5:95 to 25:75, more preferably from 10:90 to 20:80, and preferably at a temperature of from 0 °C to the boiling point of the solvent component S1 , more preferably from 10 to 100 °C, more preferably from 15 to 80 °C, more preferably from 20 to 50 °C, provided the temperature does not exceed the boiling point of the solvent component S1.

[0163] The mixing is preferably carried out at ambient pressure, e.g. at 1013 mbar ± 100 mbar. The mixing is preferably carried out for a duration of 0.5 to 40 hours, more preferably 1 to 30 hours, more preferably 2 to 25 hours, more preferably 3 to 20 hours.

[0164] Prior to mixing step a), the polymer composition P may be subjected to pre-treatment steps such as manual sorting to remove visible contaminations, washing the polymer composition P to remove contaminants, drying the polymer composition P after removing contaminants, comminution to reduce particle size and / or automatic sorting of the polymer composition P in suitable systems. Such steps may be carried out repeatedly and in any combination or sequence.

[0165] SL24 / 75188PCINEOS Styrolution Group GmbH

[0166] 19

[0167] The solvent component S1 is not particularly limited and is selected depending on the polymer A in the polymer composition P. The solvent component S1 may comprise any solvent or mixture of solvents, provided that the RED value of the solvent component S1 relative to the polymer A, determined as described above at 25 °C, is in the range from 0.5 to <1, preferably in the range from 0.65 to 0.98, more preferably in the range from 0.7 to 0.95, more preferably in the range from 0.72 to 0.93.

[0168] In some preferred embodiments, the RED value of the solvent component S1 relative to the polymer A, determined as described above, is in the range from 0.65 to 0.85, preferably from 0.71 to 0.8, more preferably from 0.73 to 0.77. For example, relative to polystyrenes (e.g. GPPS or HIPS), cyclohexene has an RED value within these ranges, which is 0.75. In other preferred embodiments, the RED value of the solvent component S1 relative to the polymer A, determined as described above, is in the range from 0.86 to 0.95, preferably from 0.87 to 0.93, more preferably from 0.89 to 0.91, For example, relative to polystyrenes (e.g. GPPS or HIPS), cyclohexane has an RED value within these ranges, which is 0.90.

[0169] For example, the solvent component S1 may be selected from the group consisting of ethers, esters, ketones, carbonate, hydrocarbons, halogenated hydrocarbons, alcohols, aldehydes, nitriles, amides, aromatic substances, nitro-aromatic substances, halogenated aromatic substances, sulfoxides, lactones and mixtures thereof. Preferably, the solvent component S1 is selected from cyclic saturated or mono-unsaturated hydrocarbons having from 5 to 8, preferably 6 atoms in the cycle, wherein one or more carbon atoms in the cycle may be optionally replaced by a heteroatom, More preferably, no carbon atoms in the cycle are replaced by heteroatoms. More preferably, no carbon atoms at all are replaced by heteroatoms.

[0170] Particularly preferably, the polymer A is GPPS or HIPS, more preferably GPPS, and the solvent component S1 is cyclohexane, cyclohexene ora mixture thereof, more preferably either cyclohexane or cyclohexene.

[0171] In step b), the mixture M obtained in step a) is subjected to conditions allowing separation of a fraction F1 comprising the polymer A and at least one fraction F2 comprising at least one additive B. Depending on the conditions allowing separation and the amount, number and types of polymer A in the polymer composition P, multiple fractions comprising the polymer A may be obtained, which can be later combined to a single fraction F1, or which may be treated individually as separate fractions F1 comprising the polymer A.

[0172] SL24 / 75188PCINEOS Styrolution Group GmbH

[0173] 20

[0174] Similarly, depending on the conditions, and the amount, number and types of additives B, multiple fractions comprising at least one additive B may be obtained, which can be later combined to a single fraction F2, or which may be treated individually as separate fractions F2, each comprising at least one additive B.

[0175] Step b) of the method of the present invention at least comprises the following steps: b1) setting the temperature of the mixture M to the temperature Ti , which is equal to or greater than the upper critical solution temperature (LICST) of the polymer A in the solvent component S1 ; and

[0176] b2) removing at least a portion of at least one additive B from the mixture M at the temperature Ti using at least one solid sorbent material SM or at least one solvent component S2.

[0177] In step b1), the temperature Ti may be any temperature that is equal to or greater than the upper critical solution temperature (LICST) of the polymer A in the solvent component S1, and preferably is below the boiling point of the solvent component S1. Preferably, the temperature Ti is within the range from 0 °C to 80 °C, more preferably from 0 °C to 60 °C, more preferably from 15 °C to 50 °C.

[0178] In some embodiments, e.g. when the RED value of the solvent component S1 relative to the polymer A is above 0.85, e.g. 0.86 to 0.95, preferably 0.7 to 0.93, more preferably from 0.89 to 0.91 (such as in case of GPPS or HIPS as the polymer A and cyclohexane as the solvent component S1), the temperature Ti is in the range from 30 °C to 80 °C, preferably 31 °C to 60 °C, more preferably 32 °C to 50 °C, provided the temperature Ti is equal to or greater than the LICST of the polymer A in the solvent component S1. In some embodiments, e.g. when the RED value of the solvent component S1 relative to the polymer A is between 0.5 and 0.85, preferably from 0.65 to 0.85, more preferably from 0.71 to 0.8, more preferably from 0.73 to 0.77 (such as in case of GPPS or HIPS as the polymer A and cyclohexene as the solvent component S1), the temperature Ti is in the range from 0 °C to 60 °C, preferably from 10 °C to 50 °C, more preferably from 15 °C to 30 °C, provided the temperature Ti is equal to or greater than the LICST of the polymer A in the solvent component S1.

[0179] The upper critical solution temperature (LICST) of the polymer A in the solvent component S1 may be determined by preparing mixtures of 10 % by weight of a model polymer A, which is synthesized to have a monomer composition (measured, e.g. by1H NMR spectroscopy) and weight-average molecular weight (measured by gel permeation chromatography calibrated to polystyrene standards) that correspond to those of the polymer A in the polymer composition P, and 90% by weight the solvent component S1 in a vial, placing the vial into a heatable bath, and visually monitoring the turbidity of the mixture, SL24 / 75188PCINEOS Styrolution Group GmbH

[0180] 21

[0181] while the mixture is agitated by magnetic stirring and the mixture temperature is increased or decreased from -40 °C to the boiling point of the solvent. The LICST is determined visually by determining the temperature at which the mixture becomes turbid or transparent.

[0182] The temperature of the mixture M can be set to the temperature Ti by any means known in the art, e.g. by heating or cooling one or more walls of the vessel in which the mixture is contained or by introducing heating or cooling elements into the mixture M.

[0183] In step b2), at least a portion of at least one additive B from the mixture M is removed at the temperature Ti using at least one solid sorbent material SM or at least one solvent component S2. Step b2) may be carried out a single time or multiple times, wherein the use of the at least one solid sorbent material SM and the use of at least one solvent component S2 may be carried out in different iterations of step b2). For example, if multiple additives B are present in the polymer composition P, step b2) may be carried out once to remove multiple additives B at the same time, or step b2) may be carried out multiple times and individually for each additive B present in the polymer composition P, wherein in each iteration of step b2), the at least one solid sorbent material SM and / or the at least one solvent component S2 can be selected individually for each additive B.

[0184] The term “sorption” refers to any type of interaction between a solid component, referred to as “sorbent material” and a further compound, wherein the interaction leads to the further compound becoming attached (also referred to as “sorbed”) to the sorbent material. Preferably, the term “sorption” refers to adsorption, absorption or a combination thereof, preferably adsorption. Accordingly, the solid sorbent material SM preferably is an adsorbent, absorbent or a combination thereof, and the term “sorbed” preferably means adsorbed, absorbed ora combination thereof. Typical sorbent materials are partly or fully insoluble in the solvent component S1, and feature a high surface area in relation to their weight. Examples are, pulverized inorganic substances, such as aluminium oxide, mica or silica, and activated charcoal (also referred to as activated carbon).

[0185] The at least one solid sorbent material SM is preferably selected from activated charcoal, aluminum oxide, calcium carbonate, silicon dioxide and combinations thereof, which have been found capable of at least partially removing additives B from the mixture M without substantially removing the at least one polymer A therefrom. More preferably, the solid sorbent material SM comprises activated charcoal, preferably having a surface area (in particular specific surface area determined by Brunauer-Emmett-Teller analysis) of at least 500 m2 / g, more preferably at least 1000 m2 / g, more preferably at least 2000 m2 / g, e.g. 2000-4000 m2 / g.

[0186] SL24 / 75188PCINEOS Styrolution Group GmbH

[0187] 22

[0188] Preferably the solid sorbent material SM comprises activated charcoal having an external surface area (Sext determined by the t-plot method) of at least 500 m2 / g, preferably at least 700 m2 / g, more preferably at least 1500 m2 / g, e.g. 1500-3000 m2 / g. Preferably the solid sorbent material SM comprises activated charcoal having a micropore area (Smicro determined by the t-plot method) below 1000 m2 / g, preferably between 200 and 600 m2 / g. Preferably, the solid sorbent material SM comprises activated charcoal having a total pore volume (Vtotdetermined by the t-plot method) of at least 0.5 cm3 / g, preferably at least 0.8 cm3 / g, more preferably at least 1 cm3 / g, more preferably at least 1.3 cm3 / g, e.g. 1.3-2.0 cm3 / g.

[0189] Preferably, the solid sorbent material SM comprises activated charcoal having a micropore volume (Vmicro determined by the t-plot method) below 0.5 cm3 / g, preferably between 0.1 and 0.4 cm3 / g, more preferably wherein the micropore volume is less than 35% of the total pore volume, preferably less than 30% of the total pore volume, more preferably less than 25% of the total pore volume, more preferably less than 20% of the total pore volume, more preferably from 5 to 15% of the total pore volume.

[0190] Preferably, the average pore width (Wavgdetermined by the Barrett-Joyner-Halenda method) is in the range from 20 to 70 A, more preferably from 30 to 60 A, morepreferably from 40 to 45 A. Preferably, the activated charcoal has FTIR absorption peaks around 1060 and 1560 cm-1. More preferably, the activated charcoal is from a renewable source and / or not fossil-based.

[0191] Preferably, the amount of activated charcoal used as the at least one solid sorbent material SM is in the range of from 10 to 50 g / L, more preferably 15 to 40 g / L, more preferably 20 to 35 g / L, based on the total volume of the mixture M comprising the polymer product P and the solvent component S1.

[0192] More preferably, the solid sorbent material SM comprises activated charcoal and at least one inorganic component.

[0193] More preferably, the inorganic component is aluminum oxide (AI2O3). Where at least two solid sorbent materials SM are used, such as activated charcoal and at least one inorganic component, such as aluminum oxide, the sorption may be carried out in at least two steps, using one or more sorbent materials in each step, or may be carried out in a single step, using a mixture of the solid sorbent materials SM. Where sorption is carried out in at least two steps, using activated charcoal and at least one inorganic component such as aluminum oxide, the step using activated charcoal is preferably carried out first.

[0194] SL24 / 75188PCINEOS Styrolution Group GmbH

[0195] 23

[0196] Where a mixture of solid sorbent materials SM is used, the solid sorbent materials are preferably layered on top of each other. In this case, if the mixture contains activated charcoal, the activated charcoal is preferably layered on top of the other sorbent materials, preferably on top of aluminum oxide.

[0197] Where at least two solid sorbent materials SM are used, such as activated charcoal and at least one inorganic component, in particular AI2O3, the mass-based ratio of the inorganic component, in particular AI2O3 to the activated charcoal is preferably in the range from 0.5:1 to 2.5:1, more preferably from 0.6:1 to 0.8:1.

[0198] The amount of the solid sorbent material SM, such as activated charcoal, is not particularly limited and will typically be selected based on the amount of the additive B in the mixture M, the solubility of thereof in the solvent component S1 at the temperature Ti, and the total amount of the mixture M.

[0199] To carry out step b2) using a solid sorbent material SM, the mixture M can be, e.g. mixed with an appropriate amount of the solid sorbent material SM with or without agitation (by means described above), and then filtered through a filter having a sufficiently small pore size to hold back the at least one solid sorbent material SM. Alternatively, the mixture M can be filtered through a packed column filled with the at least one sorbent material SM.

[0200] Preferably, a packed column filled with the at least one solid sorbent material SM is used, especially when the solubility of at least one additive B in the solvent component S1 at the temperature Ti is high, e.g. above 1% by weight, preferably above 2% by weight, more preferably above 5% by weight, based on the total weight of a solution of the respective additive B alone in the solvent component S1.

[0201] Preferably, in these cases, the aspect ratio of the packed column (length to diameter) is in the range from 2:1 to 20:1, preferably from 3:1 to 15:1, more preferably from 4:1 to 10:1. Moreover, preferably the volume of the packed column corresponds to at least 20%, preferably at least 30%, more preferably at least 50%, more preferably at least 100%, more preferably at least 150% of the volume of the mixture M that is to be subjected to sorption using the at least one solid sorbent material SM.

[0202] However, it has been found that the separation using at least one solid sorbent material SM is particularly efficient, when the solubility of the additive B in the solvent component S1 at the temperature Ti is low, preferably does not exceed 1% by weight, more preferably 0.5% by weight, more preferably 0.1% by weight, more preferably 0.05% by weight, more preferably 0.02% by weight, based on the total weight of a solution of the respective additive B alone in the solvent component S1.

[0203] SL24 / 75188PCINEOS Styrolution Group GmbH

[0204] 24

[0205] The solubility of at least one additive B in the solvent component S1 at temperature Ti can be determined, e.g. by setting up multiple closed vessels containing mixtures of the solvent component S1 and a respective additive B alone in differing amounts, setting the temperature of these mixtures to the temperature Ti, stirring the mixtures at this temperature for 24 h, and visually determining whether any undissolved residues of the additive B are detectable in the mixture.

[0206] Alternatively and preferably, the solubility can be determined by mixing a predetermined excess amount of the respective additive B alone and a predetermined amount of the solvent component S1 in a closed vial at temperature Ti, stirring the mixture at this temperature for 24 h, centrifugation of the suspension, separation of the supernatant from the sediment, drying of the sediment, and determination of the residual weight of the undissolved additive B from the sediment and / or the amount of the dissolved additive in the supernatant (e.g. by thermogravimetric analysis).

[0207] When step b2) is carried out using at least one solid sorbent material SM, a fraction F1 comprising the polymer A and the solvent component S1, and a fraction F2 comprising at least one additive B and the solid sorbent material SM is obtained. When step b2) is carried out multiple times using at least one solid sorbent material SM, multiple fractions F2 comprising the same or different additives B and the sorbent material SM can be obtained. Optionally the additive B can be extracted from the fraction F2 using a solvent in which the additive B is very well soluble, and both the additive B and the solid sorbent material SM can be recycled for further use.

[0208] When step b2) is carried out using at least one solvent component S2, the solvent component S2 used according to the present invention is selected to fulfil the following criteria (1), (2) and (3):

[0209] (1) the RED value of the solvent component S2 relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is greater than 1.0;

[0210] (2) the solubility of at least one additive B in the solvent component S2 at the temperature T 1 is greater than its solubility in solvent component S1 ; and

[0211] (3) a mixture of the solvent component S1 and the solvent component S2 at the temperature Ti is heterogeneous, when the amount of the solvent component S2 exceeds 10% by weight, preferably exceeds 5% by weight, more preferably exceeds 1% by weight, more preferably exceeds 0.1 % by weight, based on the total weight of the mixture of the solvent component S1 and the solvent component S2 (i.e. the solvent component 51 and the solvent component S2 are only miscible the amount of the solvent component 52 is below 10% by weight, preferably below 5% by weight, more preferably below 1%

[0212] SL24 / 75188PCINEOS Styrolution Group GmbH

[0213] 25

[0214] by weight, more preferably below 0.1% by weight, based on the mixture of solvent components S1 and S2).

[0215] It was found that by using a solvent component S2 fulfilling these criteria, soluble additives B can be separated from the polymer A without premature precipitation of the polymer A in the fraction F1, which often involves undesired co-precipitation of the additive B.

[0216] The RED value of the solvent component S2 relative to polymer A can be determined in the same way as the RED value of the solvent component S1 relative to polymer A, as described above. The solubility of at least one additive B in the solvent component S2 and in the solvent component S1 at temperature Ti can be determined, as explained above.

[0217] The amount of solvent component S2 at which the mixture of the solvent component S1 and the solvent component S2 at temperature Ti is heterogeneous can be determined, e.g. by setting up multiple closed vessels containing mixtures of the solvent component 51 and the solvent component S2 alone in differing amounts, setting the temperature of these mixtures to the temperature Ti, stirring the mixtures at this temperature for 1 h, allowing the mixtures to rest for 1 h, and visually determining, at which amount of S2 a phase separation can be observed.

[0218] When step b2) is carried out using solvent component S2, a fraction F1 comprising the polymer A and the solvent component S1 , and a fraction F2 comprising at least one additive B and the solvent component S2 is obtained. When step b2) is carried out multiple times using at least one solvent component S2, multiple fractions F2 comprising the same or different additives B and e.g. different solvent components S2 can be obtained. Optionally the additive B can isolated from the fraction F2 and recycled for further use, e.g. by evaporation of the solvent component S2. The evaporated solvent component 52 can then be condensed and recycled for further use.

[0219] The solvent component S2 is not particularly limited and may be any solvent or solvent mixture that fulfils the criteria (1), (2) and (3) defined above. Typically, the solvent component S2 will be selected depending on the polymer A, the respective additive B, the solvent component S1 and the temperature Ti. For example, it has been found that for polymer compositions P comprising GPPS or HIPS as the polymer A and HBCD as an additive B, a separation of the additive B from the polymer A is particularly efficient if the solvent component S1 is cyclohexene, the solvent component S2 is dimethyl sulfoxide (DMSO), and the temperature Ti is between 0 °C and 30 °C.

[0220] SL24 / 75188PCINEOS Styrolution Group GmbH

[0221] 26

[0222] Preferably, when the RED value of the solvent component S1 relative to the polymer A is in the range from 0.86 to < 1 , which often leads to Ti being in the range of > 30 to 80 °C, step b2) includes the use of the solid sorbent material SM to remove the at least one additive B, and preferably does not involve the use of the solvent component S2. In particular, since at higher temperatures the miscibility of solvents increases, it may become difficult to find a solvent component S2 that forms a heterogeneous mixture with solvent component S1 at temperature Ti, when if the amount of solvent component S2 exceeds 10% by weight.

[0223] This often leads to premature precipitation of polymer A which may be accompanied by undesired co-preci pitation of additives B. For example, this may be the case, when the polymer A is GPPS or HIPS, and the solvent component S1 is cyclohexane. Accordingly, if step b2) includes the use of a solvent component S2, the RED value of the solvent component S1 relative to the polymer A is preferably in the range from 0.5 to 0.85, which often allows Ti to be in the range of 0 °C to 30 °C. For example, this may be the case, when the polymer A is GPPS or HIPS, and the solvent component S1 is cyclohexene. A suitable solvent component S2 in this configuration is, e.g. DMSO.

[0224] In addition to the steps b1) and b2) described above, the step b) may contain conditions allowing separation of a fraction F1 comprising the polymer A from at least one fraction F2 comprising at least one additive B.

[0225] For example, if the at least one additive B comprises at least one additive B1 having a very low solubility in the solvent component S1 at the temperature Ti, e.g. lower than 0.1% by weight, preferably lower than 0.01% by weight, more preferably lower than 1 ppm by weight, based on the total weight of a solution of the additive B1 alone in the solvent component S1 (determined as disclosed above), step b) preferably includes a solid-liquid separation step at temperature Ti.

[0226] Solid-liquid separation may be carried out, e.g. by gravimetric separation, or by filtration, or a combination thereof. Gravimetric separation may include, e.g. passive sedimentation or centrifugation, preferably centrifugation, more preferably centrifugation at a G-force in the range from 100 G to 1 ,000,000 G, more preferably from 250 G to 350,000 G more preferably from 500 G to 55,000 G, more preferably from 3,000 to 20,000 G, and preferably over a period of at least 5 min, preferably 10 to 500 min, more preferably from 15 to 120 min, more preferably from 20 to 60 min.

[0227] The gravimetric separation may be repeated several times, e.g. 1-5 times, and is preferably followed by transferring the supernatant to a separate vessel, for example by means of cannula, pipette or decantation.

[0228] SL24 / 75188PCINEOS Styrolution Group GmbH

[0229] 27

[0230] Preferably, industrial scale separation techniques are used, like larger scale decanter, centrifuges, extrusion combined optionally with mechanical squeezing. Preferably solidliquid separation comprises centrifugation, filtration or a combination thereof.

[0231] Preferably, such solid-liquid separation step, if present, is carried out between steps b1) and b2), to remove a solid fraction comprising the additive B1 having a very low solubility in the solvent component S1 at the temperature Ti, forming part of the at least one fraction F2 comprising at least one additive B. For example, such solid-liquid separation step allows efficient removal of the polymeric flame retardant FR-122P from a mixture of GPPS or HIPS with cyclohexene or cyclohexane at a temperature above the LICST of the GPPS or HIPS in these solvents.

[0232] Furthermore, e.g. if the at least one additive B comprises at least one additive B2 having a sufficient solubility in the solvent component S1 at a temperature T2, which is at least 5 °C below the LICST of the polymer A in the solvent component S1 , preferably a solubility at this temperature of at least 1 ppm by weight, preferably at least 0.01% by weight, more preferably at least 0.1% by weight, based on the total weight of a solution of the additive B2 alone in the solvent component S1, step b) preferably includes a step of leaching at temperature T2.

[0233] Leaching in the present context refers to a process, at which the polymer A is dispersed or swollen, but not dissolved in the solvent component S1, and at least one additive B that is originally dissolved in the polymer A is allowed to diffuse into, and dissolve in the solvent component S1. This step allows separation of a liquid fraction comprising at least a portion of the additive B2, forming part of the at least one fraction F2 comprising at least one additive B. The undissolved polymer A can then be mixed with fresh solvent component S1, and the leaching step can optionally be repeated. In some embodiments, step b) may include leaching steps using a different solvent component than the solvent component S1, provided that the leaching is carried out at a temperature that is at least 5 °C below the LICST of the polymer A in said different solvent component.

[0234] The leaching may be carried-out batch-wise, continuously, or in a single step. For example, the additive B2 may be separated from the polymer A using a continuous stream of the solvent component S1 or a different solvent, at a temperature that is at least 5 °C below the LICST of the polymer A in the respective solvent.

[0235] Separation of a liquid fraction comprising at least a portion of the additive B2 may be carried out by any means known in the art, e.g. by filtration or gravimetric separation, as described above. Preferably, the leaching step is carried out before step b1).

[0236] SL24 / 75188PCINEOS Styrolution Group GmbH

[0237] 28

[0238] In step c), a polymer composition P1 comprising the polymer A from fraction F1 is recovered, wherein in the polymer composition P1 , the relative weight content of components that are not polymers comprising repeating units of aromatic vinyl monomer A1 is reduced by at least 50%, preferably at least 70% by weight, more preferably by at least 80% by weight, more preferably by at least 90% by weight, more preferably by at least 95% by weight, compared to the polymer composition P.

[0239] This means that, for example, if the polymer composition P contains (100 - x)% by weight of the polymer A comprising repeating units of at least one aromatic vinyl monomer A1 and x% by weight of other components that are not polymers comprising repeating units of aromatic vinyl monomer A1 (including the at least one additive B, impurities, contaminants, and polymers lacking aromatic vinyl monomer A1), based on the total weight of the polymer composition P, the polymer composition P1 will contain (100 - y)% by weight of the polymer A and y% by weight of the other components, based on the polymer composition P1, wherein y < 0.5x, preferably y < 0.3x, more preferably y < 0.2x, more preferably y < 0.1x, more preferably y < 0.05x.

[0240] Preferably, step c) of the method of the present invention comprises precipitation of the polymer composition P1 from the fraction F1 comprising the polymer A obtained from step b) of the method. Precipitation may be carried out by any means known in the art for precipitating polymers from their solutions.

[0241] Preferably precipitation comprises one or more of the following steps:

[0242] c1) at temperature Ti, mixing the fraction F1 with a solvent component S3, which is preferably the same as solvent component S2, having an RED relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), in the range from 0.96 to 1.1, wherein the amount of solvent component S3 is preferably in the range from 0.1 to 15% by weight, more preferably in the range from 0.1 to 2% by weight, based on the total weight of the fraction F1 and the solvent component S3, and preferably wherein a mixture of the solvent component S1 and the solvent component S3 at the temperature Ti is homogeneous, when the amount of the solvent component S3 is 0.1 to 2% by weight, based on the total weight of the mixture of the solvent component S1 and the solvent component S3; and at the temperature Ti, mixing the mixture of fraction F1 and solvent component S3 with a solvent component S4 having a RED relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), of equal to or greater than 1.1, wherein the amount of solvent component S4 is preferably greater than 0.4% by weight, more preferably greater than 1% by weight based on the total weight of the

[0243] SL24 / 75188PCINEOS Styrolution Group GmbH

[0244] 29

[0245] fraction F1 , the solvent component S3 and the solvent component S4, and preferably at least 10 times less, more preferably at least 20 times less, than the amount of solvent component S4 required for precipitation of the polymer A in the absence of solvent component S3, wherein a mixture of the solvent components S1 , S3 and S4 at the temperature Ti is homogeneous when the amount of solvent component 54 is within the specified range; or

[0246] mixing solvent component S3 with solvent component S4 and then mixing the mixture of solvent components S3 and S4 with the fraction F1 under these conditions c2) at temperature Ti, mixing the fraction F1 with a solvent component S5 having an RED relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), in the range from 0.75 to 2.1 , wherein the amount of solvent component 55 is in the range from 0.2 to 40% by weight, based on the total weight of the fraction F1 and the solvent component S5, wherein a mixture of the solvent component S1 and the solvent component S5 at the temperature Ti is homogeneous when the amount of solvent component S5 is within the specified range; and optionally

[0247] cooling the mixture of the fraction F1 and the solvent component S5 from the temperature Ti to a temperature T3, wherein T3 is lower than Ti by at least 3 °C; c3) at temperature Ti, mixing with the fraction F1 a solvent component S4 having a RED relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), of equal to or greater than 1.1, wherein the amount of solvent component S4 is greater than 5% by weight, but less than 75% by weight, based on the total weight of solvent components S1 and S4, wherein a mixture of the solvent component S1 and solvent component S4 at the temperature Ti is homogeneous when the amount of solvent component S4 is within the specified range;

[0248] c4) at temperature Ti, adding the fraction F1 to a solvent component S4 having a RED relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), of equal to or greater than 1.1, wherein the weight ratio of the total amount of fraction F1 to the total amount of solvent component S4 is preferably in the range from 1:2 to 1:3, wherein the fraction F1 is added to the solvent component S4 continuously and simultaneously the precipitated polymer is removed continuously, or wherein the fraction F1 is added to the solvent component S4 batch-wise, preferably in batches of 1:8 to 1:15 (weight ratio of F1 batches to S4), and the precipitated polymer is removed between the batches;

[0249] c5) evaporating the solvent components in the fraction F1 at a temperature in the range from 28 °C to 100 °C, preferably in the range from 30 to 90 °C, more preferably in the range from 50 to 80 °C and / or under subatmospheric pressure, preferably in the range from 0.1 to 900 mbar, more preferably from 0.1 to 800 mbar, more preferably from 0.1 to 500 mbar, more preferably from 0.1 to 100 mbar;

[0250] SL24 / 75188PCINEOS Styrolution Group GmbH

[0251] 30

[0252] c6) treating the fraction F1 with water vapor, thereby evaporating the solvent components in the fraction F1, preferably only partially evaporating the solvent components in the fraction F1, more preferably evaporating from 50 to 95% by weight, preferably from 60 to 90% by weight, more preferably from 70 to 80% by weight of the solvent components in fraction F1;

[0253] c7) setting the temperature of the fraction F1 comprising the polymer A and the solvent component S1 to a temperature T2, which is at least 5 °C, preferably at least 10 °C below the LICST of the polymer A in the solvent component S1 , preferably where the temperature T1 set before this step is in the range from 30 °C to 80 °C.

[0254] Precipitation is preferably followed by a solid / liquid separation step, to separate the precipitated polymer composition P1 comprising the polymer A from the solvent components and the dissolved residues. Such solid / liquid separation may be carried out, e.g. by the methods described above for solid / liquid separation. Preferably, solid / liquid separation involves filtration and / or centrifugation, more preferably centrifugation as described above.

[0255] In general, precipitation of solid components (such as polymers) dissolved in a solvent by means of an antisolvent (a fluid in which said solid components are insoluble) is known to those skilled in the art. However, such precipitations typically require very large amounts of the antisolvents, with ratios of antisolvent:solvent usually being above 3:1 (i.e. the content of the antisolvent is usually at least 80% by weight), often above 5:1.

[0256] It has now surprisingly been found that the amounts of antisolvent can be substantially reduced and / or the homogeneity of the precipitated polymer product P1 can be substantially improved if the precipitation is carried out as described for steps c1), c2), c3) and / or c4).

[0257] In step c1), a solvent component S3 is mixed with the fraction F1 at a temperature T1, which is equal to or greater than the upper critical solution temperature (LICST) of the polymer A in the solvent component S1 , and may be the same as, or different from, the temperature T1 used in step b). The solvent component S3 has an RED value (determined as described above) relative to the polymer A in the range from 0.96 to 1.1, preferably in the range from 1 to 1.08, more preferably from 1.03 to 1.07, and is preferably the same solvent component as solvent component S2.

[0258] The amount of solvent component S3 mixed with the fraction F1 in step c1) is preferably in the range from 0.1 to 15% by weight, more preferably from 0.1 to 10% by weight, more preferably from 0.1 to 5% by weight, more preferably in the range from 0.1 to 2% by weight, based on the total weight of the fraction F1 and the solvent component S3. SL24 / 75188PCINEOS Styrolution Group GmbH

[0259] 31

[0260] Preferably, the solvent component S3 is selected, so that mixtures thereof with the solvent component S1 at the temperature Ti are homogeneous, when the amount of the solvent component S3 is in the specified range, especially in the range from 0.1 to 2% by weight, based on the total weight of the mixture of the solvent component S1 and the solvent component S3. More preferably, mixtures of the solvent component S3 are heterogeneous, when the amount of the solvent component S3 exceeds 10% by weight, preferably exceeds 5% by weight, more preferably exceeds 2% by weight, based on the total weight of the mixture of the solvent component S1 and the solvent component S3.

[0261] After addition of solvent component S3, a solvent component S4, which is different from both solvent component S1 and solvent component S3, is mixed with the mixture of fraction F1 and solvent component S3 at temperature Ti. The solvent component S4 has an RED value (determined as described above) relative to the polymer A of equal to or greater than 1.1, preferably in the range from 1.15 to 2.1, more preferably from 1.2 to 2.0, more preferably from 1.3 to 1.85, more preferably from 1.4 to 1.7. The amount of solvent component S4 required to precipitate a polymer product P1 from the mixture of fraction F1 and solvent component S3 is typically greater than 0.4% by weight, sometimes greater than 1% by weight.

[0262] This is typically at least 10 times less, often at least 20 times less, in particular at least 22 times less than the amount of solvent component S4 required to precipitate the same amount of polymer product P1 in the absence of the solvent component S3. Preferably, the amount of solvent component S4 mixed with the mixture of fraction F1 and solvent component S3 is in the range from 0.4 to 50% by weight, preferably in the range from 0.4 to 10% by weight, more preferably in the range from 0.4 to 5% by weight, more preferably in the range from 0.4 to 1.5% by weight, based on the total weight of the fraction F1 , the solvent component S3 and the solvent component S4.

[0263] Alternatively, the amount of solvent component S4 may be preferably in the range from 0.8 to 20% by weight, more preferably in the range from 1 to 10% by weight, more preferably in the range from 1.5 to 5% by weight, based on the total weight of the fraction F1, the solvent component S3 and the solvent component S4. Solvent component S4 is selected, so that within the specified amounts mixtures of the solvent components S1, S3 and S4 at the temperature Ti, are homogeneous. Preferably, mixtures of the solvent components S1 and S4 alone are also homogeneous, if the amount of solvent component S4 is in the specified ranges, based on the total weight of the solvent components S1 and S4.

[0264] SL24 / 75188PCINEOS Styrolution Group GmbH

[0265] 32

[0266] It has been found that step c1) leads to a substantial reduction of required antisolvent for precipitation of the polymer A, and produces a precipitate of substantially finer polymer particles compared with the use of solvent component S4 alone. For example, when the polymer A is GPPS or HIPS and the solvent component S1 is cyclohexene (RED of 0.75 relative to polymer A), DMSO (RED of 1.06 relative to polymer A) may be used as solvent component S3 and ethanol (RED of 1.49 relative to polymer A) may be used as solvent component S4, e.g. at a temperature in the range from 0 to 30 °C.

[0267] Alternatively, precipitation can also be carried out by preparing a mixture of solvent component S3 and solvent component S4, and mixing said mixture with the fraction F1, wherein the amounts are as specified above.

[0268] Optionally, the mixture of fraction F1 and solvent components S3 and S4 can be cooled, e.g. to a temperature T3, wherein T3 is lower than T1 by at least 3 °C, preferably by at least 5 °C, more preferably below the LICST of the polymer A in the solvent component S1, which can further increase precipitation yields.

[0269] In step c2), a solvent component S5 is added to the fraction F1 at a temperature T1, which is equal to or greater than the upper critical solution temperature (LICST) of the polymer A in the solvent component S1 , and may be the same as, or different from, the temperature T1 used in step b). The solvent component S5 has an RED value (determined as described above) relative to the polymer A in the range from 0.75 to 2.1, preferably in the range from 0.9 to 1.8, more preferably from 1.0 to 1.7, more preferably from 1.3 to 1.6, and may be the same as, or different than, solvent component S4 or solvent component S3 described above for step c1).

[0270] The amount of solvent component S5 added to the fraction F1 in step c1) is in in the range from 0.2 to 40% by weight, preferably from 0.5 to 20% by weight, more preferably from 1 to 15% by weight, based on the total weight of the fraction F1 and the solvent component S5. Solvent component S5 is selected, so that within the specified amounts mixtures of the solvent components S1 and S5 at the temperature T1, are homogeneous. Preferably, solvent component S5 is selected so that its RED value relative to the polymer A is higher than the RED value of solvent component S1 relative to the polymer A.

[0271] Optionally, and depending on the selected solvent component S5, the mixture of the fraction F1 and the solvent component S5 can be cooled from temperature T1 to a temperature T3, wherein T3 is lower than T1 by at least 3 °C, preferably by at least 5 °C, more preferably below the LICST of the polymer A in the solvent component S1.

[0272] SL24 / 75188PCINEOS Styrolution Group GmbH

[0273] 33

[0274] For example, cooling may be necessary if the RED of the solvent component S5 relative to the polymer A is below 1 , and / or if the amount thereof is 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, more preferably 3% by weight or less. Preferably, cooling to temperature T3 is carried out regardless of the solvent component S5 or its amount.

[0275] It has been surprisingly found that the use of a solvent component S5 can facilitate precipitation of the polymer A from the fraction F1, even if the RED value of the solvent component S5 relative to the polymer A is below 1 , which is observed especially if the mixture of the fraction F1 and the solvent component S5 is cooled to a temperature T3.

[0276] Preferably, the solvent component S5 and its amount are selected, so that the dielectric constant of a mixture of solvent component S1 and the solvent component S5 is greater than 2.5, more preferably greater than 3.0, more preferably greater than 3.3. It was surprisingly found that at these dielectric constants, the precipitation of styrene-containing polymer A, in particular polystyrene, can be easily carried out at room temperature (23 °C).

[0277] The dielectric constant of the mixture can be calculated as the molar average of the dielectric constants of the individual components (Pmix = P1X1 + P2X2), where Pmix, Pi and P2 are the dielectric constants of the mixture, the first solvent and the second solvent, respectively, and xi and X2 are the amounts of the first solvent and the second solvent in mol.-%, based on the total moles of the two solvents.

[0278] In step c3), a solvent component S4 which is defined as described above for step c1), is mixed with the fraction F1 at a temperature T1, which is equal to or greater than the upper critical solution temperature (LICST) of the polymer A in the solvent component S1. The amount of solvent component S4 mixed with fraction F1 is greater than 5% by weight, preferably greater than 10% by weight, but less than 75% by weight, preferably less than 50% by weight, based on the total weight of solvent components S1 and S4.

[0279] Solvent component S4 is selected so that mixtures of the solvent components S1 and S4 are homogeneous, if the amount of solvent component S4 is in the specified ranges, based on the total weight of the solvent components S1 and S4. Preferably, mixing is carried out by adding the fraction F1 to the solvent component S4, preferably while agitating the mixture.

[0280] It has been surprisingly found that the use of a solvent component S1 as defined herein as a solvent for the polymer A, and of a solvent component S4 as defined herein as an

[0281] SL24 / 75188PCINEOS Styrolution Group GmbH

[0282] 34

[0283] antisolvent, allows substantially reducing the amount of antisolvent required for precipitating the polymer A from the fraction F1 , from the typical amounts of 75% by weight or greater known in the art to less than 75% by weight, based on the total weight of solvent components S1 and S4.

[0284] In step c4), the fraction F1 is added to a solvent component S4, as defined above, continuously, while the precipitated polymer A is simultaneously continuously removed (withdrawn) from the resultant mixture, or batch-wise, while the precipitated polymer A is removed (withdrawn) from the resultant mixture between the additions of the batches. Preferably, the weight ratio of the total amount of fraction F1 to the total amount of solvent component S4 is in the range from 1:2 to 1:3.

[0285] Preferably, fraction F1 is added to the solvent component S4 batch-wise. In this case, the size of the batches (weight ratio of each F1 batch to S4) is preferably 1:8 or less, preferably 1:8 to 1:15, and / or the number of batches is preferably at least 4, preferably from 4 to 5.

[0286] It has surprisingly been found that by carrying out step c4), the precipitated polymer product P1 is obtained in a substantially finer form and does not form large polymer aggregates which are not desirable.

[0287] In step c5), evaporation is preferably carried out on a substrate, e.g. in a vessel, mold or on a plate, with a surface having a shape corresponding to a desired shape of a polymer product. This allows obtaining a desired shape of the obtained polymer by selecting the appropriate shape of the vessel, in which step c5) is carried out.

[0288] In step c6), evaporation preferably involves only partially evaporating the solvent components in the fraction F1, more preferably evaporating from 50 to 95% by weight, preferably from 60 to 90% by weight, more preferably from 70 to 80% by weight of the solvent components in fraction F1. By only partial evaporation, it is possible to avoid obtaining a dry rigid polymer block that may be difficult to isolate.

[0289] Preferably, step c) comprises one or more steps selected from c1), c2) (preferably where the cooling to temperature T3 is carried out), c3) and c4), more preferably one or more steps selected from c1), c2) where the cooling to temperature T3 is carried out, and c4), more preferably one or more steps selected from c1) and c4), more preferably at least step c1).

[0290] In a preferred embodiment, the method of the present invention comprises the following steps:

[0291] SL24 / 75188PCINEOS Styrolution Group GmbH

[0292] 35

[0293] a) mixing a polymer composition P, preferably post-consumer and / or post-industrial waste, comprising

[0294] A) a polymer A comprising mainly general purpose polystyrene and / or high-im- pact polystyrene, preferably general purpose polystyrene; and

[0295] B) at least one additive B, comprising at least one flame retardant selected from brominated or phosphorous-containing hydrocarbons, preferably hexabromocyclododecane (HBCD) tetrabromobisphenol A (TBBPA), triphenyl phosphate, decabromodiphenyl ethane (DBDPE) and / or polybrominated styrenebutadiene copolymers, preferably at least HBCD;

[0296] with a solvent component S1, to obtain a mixture M;

[0297] b) subjecting the mixture M to conditions allowing separation of a fraction F1 comprising the polymer A from at least one fraction F2 comprising at least one flame retardant; and

[0298] c) recovering a polymer composition P1 , mainly comprising the polymer A from fraction F1,

[0299] wherein the solvent component S1 is cyclohexane;

[0300] wherein step b) comprises the following steps:

[0301] ba) optionally, at a temperature T2 which is at least 5 °C below the LICST of the polymer A in cyclohexane, leaching at least a portion of the at least one additive B from the polymer composition P using cyclohexane, to remove a liquid fraction comprising at least a portion of at least one additive B, forming part of the at least one fraction F2;

[0302] bb) setting the temperature of the mixture M to a temperature T1 in the range from 30 to 80 °C, preferably from 30 to 60 °C;

[0303] be) optionally subjecting the mixture M to filtration, centrifugation or a combination thereof, to remove a solid fraction comprising at least a portion of at least one additive B, forming part of the at least one fraction F2; and

[0304] bd) removing the additive B from the mixture M at the temperature T1 using activated charcoal ora combination thereof with aluminium oxide, to obtain a fraction F1 comprising the polymer A and the solvent component S1 and a fraction F2 comprising the additive B and the solid sorbent material.

[0305] Preferably, step c) of this embodiment involves cooling the fraction F1 comprising the polymer A and the solvent component S1 to a temperature below 30 °C, more preferably in the range from 0 °C to 29 °C, more preferably from 15 °C to 28 °C, more preferably from 20 °C to 26 °C, to precipitate the polymer product P1 comprising the polymer A. More preferably, step c) of this embodiment further involves filtration or centrifugation after the precipitation.

[0306] SL24 / 75188PCINEOS Styrolution Group GmbH

[0307] 36

[0308] Preferably, step ba) is carried out at least if HBCD is present. Preferably, step be) is carried out at least if one or more of DBDPE and / or polybrominated styrene-butadiene copolymers are present.

[0309] In another preferred embodiment, the method of the present invention comprises the following steps:

[0310] a) mixing a polymer composition P, preferably post-consumer and / or post-industrial waste, comprising

[0311] A) a polymer A comprising mainly general purpose polystyrene and / or high-im- pact polystyrene, preferably general purpose polystyrene; and

[0312] B) at least one additive B selected from brominated or phosphorous-containing hydrocarbons, preferably hexabromocyclododecane (HBCD) tetrabromobisphenol A (TBBPA), triphenyl phosphate, decabromodiphenyl ethane (DBDPE) and / or polybrominated styrene-butadiene copolymers; with a solvent component S1, to obtain a mixture M;

[0313] b) subjecting the mixture M to conditions allowing separation of a fraction F1 , mainly comprising the polymer A from at least one fraction F2 comprising at least one flame retardant; and

[0314] c) recovering a polymer composition P1 comprising the polymer A from fraction F1, wherein the solvent component S1 is cyclohexene;

[0315] wherein step b) comprises the following steps:

[0316] be) setting the temperature of the mixture M to a temperature Ti in the range from 0 to 29 °C, preferably from 15 to 27 °C;

[0317] bf) optionally subjecting the mixture M to filtration, centrifugation or a combination thereof, to remove a solid fraction comprising at least a portion of at least one additive B, forming part of the at least one fraction F2; and

[0318] bg) removing the additive B from the mixture M at the temperature Ti using activated charcoal or a combination thereof with aluminium oxide as the solid sorbent material SM or dimethyl sulfoxide as at least one solvent component S2, to obtain a fraction F1 comprising the polymer A and the solvent component S1 and a fraction F2 comprising the additive B and the solid sorbent material SM or the solvent component S2.

[0319] Preferably, step c) of this embodiment involves precipitation according to step c1) and / or step c4) as disclosed above. More preferably, step c) of this embodiment further involves filtration or centrifugation after the precipitation.

[0320] Preferably, step bf) is carried out at least if one or more of DBDPE and / or polybrominated styrene-butadiene copolymers are present.

[0321] SL24 / 75188PCINEOS Styrolution Group GmbH

[0322] 37

[0323] Preferably, step be) is preceded by a step of leaching using cyclohexane at a temperature which is at least 5 °C below the LICST of the polymer A in cyclohexane. Preferably, step bg) involves the use of dimethyl sulfoxide as at least one solvent component S2 at least if HBCD is present.

[0324] It has surprisingly been found that, regardless of the conditions employed in step b) allowing separation of a fraction F1 from at least one fraction F2, steps c1), c2), c3) and / or c4) described above allow isolation of a homogeneous polymer composition P1 in good yields. Another aspect of the present invention is therefore A method of processing a polymer composition P, comprising the steps:

[0325] a) mixing a polymer composition P, preferably comprising or consisting of post-consumer and / or post-industrial waste, comprising

[0326] A) a polymer A comprising repeating units of at least one aromatic vinyl monomer A1, preferably general purpose polystyrene and / or high impact polystyrene; and

[0327] B) at least one additive B, preferably a colorant and / or flame retardant and / or stabilizer and / or processing agent, more preferably a flame retardant, more preferably a halogenated flame retardant;

[0328] with a solvent component S1, to obtain a mixture M;

[0329] b) subjecting the mixture M to conditions allowing separation of a fraction F1 comprising the polymer A from at least one fraction F2 comprising at least one additive B; and

[0330] c) recovering a polymer composition P1 comprising the polymer A from fraction F1, wherein in the polymer composition P1 , the relative weight content of components that are not polymers comprising repeating units of aromatic vinyl monomer A1 is reduced by at least 50%, preferably at least 70% by weight, more preferably by at least 80% by weight, more preferably by at least 90% by weight, more preferably by at least 95% by weight, compared to the polymer composition P,

[0331] wherein the RED value of the solvent component S1 relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is in the range from 0.5 to <1; and

[0332] wherein step c) comprises one or more of the steps c1), c2), c3) and c4) as described above:

[0333] Preferably, step b) of this method comprises a solid-liquid separation step as disclosed above, a leaching step as disclosed above, a separation step involving a solid sorbent material SM as disclosed above and / or a separation step involving a solvent component S2 as disclosed above.

[0334] SL24 / 75188PCINEOS Styrolution Group GmbH

[0335] 38

[0336] More preferably, this method is the same method as described above, wherein step b) comprises steps b1) and b2). The steps, components and embodiments in this method are preferably those defined above.

[0337] Moreover, it has surprisingly been found that, if the RED value of the solvent component S1 relative to the polymer A is in the range of from 0.86 to 0.95, as is the case for cyclohexane with polystyrenes, removal of additives and contaminants and precipitation can be conveniently carried out at two different temperatures, without the need of antisolvents or other precipitation means in the process. Another aspect of the present invention is therefore a method of processing a polymer composition P, comprising the steps: a) mixing a polymer composition P, preferably comprising or consisting of post-consumer and / or post-industrial waste, comprising

[0338] A) a polymer A comprising repeating units of at least one aromatic vinyl monomer A1, preferably general purpose polystyrene and / or high impact polystyrene; and

[0339] B) at least one additive B, preferably a colorant and / or flame retardant and / or stabilizer and / or processing agent, more preferably a flame retardant, more preferably a halogenated flame retardant;

[0340] with a solvent component S1, to obtain a mixture M;

[0341] b) subjecting the mixture M to conditions allowing separation of a fraction F1 comprising the polymer A from at least one fraction F2 comprising at least one additive B; and

[0342] c) recovering a polymer composition P1 comprising the polymer A from fraction F1, wherein in the polymer composition P1 , the relative weight content of components that are not polymers comprising repeating units of aromatic vinyl monomer A1 is reduced by at least 50%, preferably at least 70% by weight, more preferably by at least 80% by weight, more preferably by at least 90% by weight, more preferably by at least 95% by weight, compared to the polymer composition P, wherein the RED value of the solvent component S1 relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is in the range from 0.86 to 0.95, preferably in the range from 0.88 to 0.92, more preferably from 0.89 to 0.91; and wherein step b) comprises the following steps:

[0343] bg) at a temperature T2 which is at least 5 °C below the LICST of the polymer A in the solvent component S1 , preferably between 0°C and 27 °C, more preferably between 15 °C and 25 °C, leaching at least a portion of the at least one additive B from the polymer composition P using the solvent component S1, to remove a liquid fraction comprising at least a portion of at least one additive B, forming part of the at least one fraction F2;

[0344] SL24 / 75188PCINEOS Styrolution Group GmbH

[0345] 39

[0346] bh) setting the temperature of the mixture M to a temperature Ti that is equal to or greater than the LICST of the polymer A in the solvent component S1 , preferably in the range from 30 to 80 °C, more preferably from 30 to 60 °C; and bi) subjecting the mixture M to filtration, centrifugation or a combination thereof, to remove a solid fraction comprising insoluble particles; and

[0347] wherein step c) comprises cooling the fraction F1 obtained in step b) to a temperature T2 which is at least 5 °C below the LICST of the polymer A in the solvent component S1 , preferably between 0°C and 27 °C, more preferably between 15 °C and 25 °C to precipitate the polymer composition P1.

[0348] Preferably, step b) of this method further comprises a separation step involving a solid sorbent material SM as disclosed above and / or a separation step involving a solvent component S2 as disclosed above. More preferably, this method is the same method as described above, wherein step b) comprises steps b1) and b2). The steps, components and embodiments in this method are preferably those defined above. Preferably, the polymer A in this method is high impact polystyrene (HIPS) or general purpose polystyrene (GPPS), more preferably HIPS.

[0349] Another aspect of the present invention is a polymer composition P1 obtained by any method of the invention, comprising general purpose polystyrene and / or high impact polystyrene as polymer A, and having a content of the at least one additive B below 0.5% by weight, preferably below 0.01% by weight, more preferably from 1 ppb to 1 ppm by weight, based on the total weight of the polymer composition P1.

[0350] The polymer composition P1 may be further processed and used for any purpose, for which the polymer A is typically used. For example, the polymer composition P1 can be used to prepare a molded article. For example, the polymer composition P1 may be further processed, preferably by drying, washing, extrusion and / or calendering, or can be used for the preparation of molded articles by any means known in the art, such as injection molding, extrusion, rotomolding, coating, etc. The polymer composition P1 may be used optionally with as a mixture with virgin materials, such as virgin polymers (preferably virgin polymers A) and additives.

[0351] The invention is illustrated in more detail by following examples and claims and Figures.

[0352] Examples

[0353] The following solvents were acquired and used the examples:

[0354] SL24 / 75188PCINEOS Styrolution Group GmbH

[0355] 40

[0356] acetone (ChemLab, >99%), n-butyl acetate (ThermoFisher Scientific, 99%), cyclohexane (ChemLab, >99.5%), cyclohexene (ChemLab, >99%), diethyl carbonate (SigmaAI-drich, 99%), ethanol (ChemLab, >99%), ethyl acetate (ChemLab, >99.5%), ethyl benzene (SigmaAldrich, >99, dimethyl sulfoxide (ChemLab, >99.9%), dodecane (ThermoFisher Scientific, >99%), heptane (ChemLab, >99%), isobutyl isobutyrate (ThermoFisher Scientific, 98%), methanol (Merck Life Science, 99.8%), 4-methyl-2-pentanol (Merck Life Science, 99%), methyl ethyl ketone (MEK) (ChemLab, >99.5%), pentane (ThermoFisher Scientific, 98%), 2-pentanone (ThermoFisher Scientific, 99%), 2-propa-nol (VWR, >98%), xylene isomer mixture (ChemLab, >99%), 1,2,3,4-tetrahydronaphtha-lene (ThermoFisher Scientific, 97%).

[0357] Polystyrene pellets made of General Purpose Polystyrene “GPPS” (Styrolution® PS 168 N; additivated with 600 ppm Zinc stearate and 175 ppm wax), General Purpose Polystyrene “GPPS” (Styrolution® PS 158 N; additivated with 600 ppm Zinc stearate and 175 ppm wax) and High Impact Polystyrene (Styrolution® HIPS 468N; rubber content 8.1 wt.-%; additivated with 2.4 wt.-% mineral oil, 600 ppm Zinc stearate and 400 ppm of antioxidants) were acquired from INEOS Styrolution.

[0358] Different post-consumer polystyrene waste samples (WEEE 1 and WEEE 2; WEEE = Waste of Electric and Electronic Equipment) were collected from different waste company suppliers and pre-consumer EPS (expanded polystyrene foam) and XPS (extruded polystyrene foam).

[0359] Insulation boards were bought in DIY stores. The latter were designated as “pure EPS” and “pure XPS”, respectively, and used as model samples. The flame retardants hexabromocyclododecane (HBCD) and polybrominated styrene-butadiene copolymer (FR-122P) were acquired from Neue Materialien Bayreuth GmbH.

[0360] The flame retardant products TBBPA and TPHP were acquired from Merck KGaA, while DBDPE was acquired from Centexbel.

[0361] Three different types of activated carbon were used as adsorbent materials:

[0362] AC-01 (Merck KGaA), AC-84 (DESOTEC), and AC-87 (DESOTEC).

[0363] The polymer samples as acquired are summarized in Table 1.

[0364] The samples (fish boxes and packaging) were dried in an oven at 70 °C to constant weight, washed in a washing machine with detergent at 90 °C, and dried in the oven at 70 °C again to constant weight (approximately 5 days).

[0365] SL24 / 75188PCINEOS Styrolution Group GmbH

[0366] 41

[0367] The level of moisture (wt.-% moisture) was determined by weighing the sample before and after the first drying step and subtracting the determined weights from each other. The level of dirtiness (wt.-% dirt) was determined by weighing the sample after the first and second drying step and subtracting the determined weights from each other.

[0368] FIG. 1 shows the appearance of the waste before and after washing and drying.

[0369] FIG. 1A shows the appearance of the pure XPS sample (left; beige) pure EPS sample (right, white).

[0370] Table 1. Sample overview (wt.-% are based on the total weight of the sample)

[0371]

[0372] SL24 / 75188PCINEOS Styrolution Group GmbH

[0373] 42

[0374]

[0375] Preparation and characterization of solid sorbent materials

[0376] The activated carbon adsorbent materials were individually crushed in an Anton Paar BM500 ball mill for 1.5 minutes at 7.00 Hz to obtain fine powders. The powders were subsequently sieved for the fraction between 32 and 45 pm mesh size. Prior to the experiments, the powders were dried in an oven at 368 K for 12 h and cooled down to room temperature in a desiccator to prevent airborne contaminations such as water vapor.

[0377] Nitrogen adsorption-desorption isotherms were constructed for the adsorbent materials by using a Micromeritics Tristar II 3020 Analyzer operated at 77 K. The specific surface area (SBET) was calculated via a Brunauer-Emmett-Teller (BET) analysis, while the t-plot method was used to determine the external surface area (Sext), the micropore area (Smi-cro), the total pore volume (Vtot), and the micropore volume (Vmicro).

[0378] The average pore width was estimated via the Barrett-Joyner-Halenda method (Wavg). To investigate the surface morphology of the adsorbent materials, a scanning electron microscopy (SEM) analysis was performed with a JEOL JSM-7600F. Furthermore, Fourier transformed infrared spectroscopy (FTIR) was used to identify changes in surface chemistry before and after adsorption, using a Nicolet iS20 FTIR Spectrometer.

[0379] FIG. 2 shows the nitrogen adsorption isotherms for AC-01 (dries), AC-84 (squares) and AC-87 (triangles) at a temperature of 77 K.

[0380] FIG. 3 shows the SEM images for AC-01 (A), AC-84 (B) and AC-87 (C).

[0381] Table 2 summarizes the different characteristics of the adsorbent materials.

[0382] From the data, it is evident that AC-84 has the highest specific surface area SBET with 2164 m2 / g compared to 1214 and 947 m2 / g for AC-01 and AC-87, respectively.

[0383] SL24 / 75188PCINEOS Styrolution Group GmbH

[0384] 43

[0385] Furthermore, AC-84 has the highest total pore volume Vtot, yet the lowest micropore volume Vmicro, where only about 14% of its total pore volume is occupied by micropores compared to 24 and 31% for AC-01 and AC-87, respectively. Similarly, the micropore area Smicro is the lowest for AC-84 among the three activated carbons.

[0386] Table 2. Properties of the activated carbons / charcoals

[0387]

[0388] With respect to the morphology, the activated carbons appear irregular and fractured (FIG. 3). In general, they present a lot of similarities, yet the texture of AC-87 is found to be more smooth compared to AC-01 and AC-84. The FTIR spectra of AC-01 and AC-84 before adsorption show very similar absorption peaks, among which the most prominent signals are observed at 1060 and 1560 cm-1. These peaks are related to the stretching of C-0 and C=C bonds, respectively, which are absent in the case of AC-87. The latter is most likely due to a difference in activation process among the adsorbents or to variations in the source material from which they were initially derived. In particular, AC-01 and AC-84 are derived from renewable sources, while AC-87 is fossil based. Nevertheless, all three adsorbent materials show the highest absorbance at wavenumbers smaller than 700 cm-1, which is indicative for C-C stretching, common in activated carbons.

[0389] Quantification of flame retardants in samples

[0390] The flame retardant identification and quantification was done by using Pyrolysis gas chromatography mass spectroscopy (Pyro-GC-MS). A Shimadzu GCMS-QP2020 NX gas chromatography-mass spectrometer (GC-MS) equipped with an Agilent HP-5ms capillary column (30 m x 0.25 mm ID, 0.25 zm thickness, with a temperature limit of -60 °C to 325 °C) and coupled to an OPTIC-4 pyrolysis unit, was used to identify and quantify dissolved flame retardants, i.e. from solution. An AQC-6000 Plus autosampler was used in combination with this pyrolysis-GC-MS configuration. For each (dissolved) flame retardant, the GC-MS method and the pyrolysis program were first optimized, after which the corresponding calibration curves were established. Table 3 shows the optimized pyrolysis parameters for analysis of HBCD, TBBPA and TPHP, and Table 4 shows the optimized GC-MS parameters for the analysis of HBCD, TBBPA and TPHP.

[0391] SL24 / 75188PCINEOS Styrolution Group GmbH

[0392] 44

[0393] FIG. 4 shows the calibration curves plotted according to the measurements and used for the quantification of HBCD in (A) n-butyl acetate and (B) cyclohexene.

[0394] FIG. 5 shows the calibration curves plotted according to the measurements and used for the quantification of TBBPA in (A) n-butyl acetate and (B) cyclohexene.

[0395] FIG. 6 shows the calibration curves plotted according to the measurements and used for the quantification of TPHP in (A) n-butyl acetate and (B) cyclohexene.

[0396] FIG.7 shows the calibration curve plotted according to the measurements and used for the quantification of FR-122P in xylene.

[0397] A detailed overview of this, including the applied temperature profiles, are provided in Tables 3 and 4 and FIG. 4 to 6. Samples of 10 pL are carefully weighed, placed into a microvial, and subsequently loaded onto the pyrolysis-GC-MS.

[0398] Table 3. Optimized pyrolysis parameters for analysis of HBCD, TBBPA and TPHP

[0399]

[0400] Table 4. Optimized GC-MS parameters for the analysis of HBCD, TBBPA and TPHP

[0401]

[0402] SL24 / 75188PCINEOS Styrolution Group GmbH

[0403] 45

[0404] In the presence of PS, and in the case where the flame retardants were not dissolved, the quantification of the flame retardant in solution was done by turbidity measurements using a turbidimeter (model HI98703 by Hanna Instruments).

[0405] FIG.8 shows the calibration curve plotted according to the measurements and used for the quantification of (A) DBDPE and (B) FR-122P.

[0406] Quantification of flame retardants in samples were also complemented with combustion ion chromatography (IC combustion) when necessary and especially when low amounts of flame retardants were present (equal or less than 400 ppm).

[0407] To demonstrate the purification potential of the adsorption process in terms of (dissolved) flame retardant removal, a semi-quantitative methodology was applied.

[0408] The removal efficiency (RE) was calculated as follows:

[0409]

[0410] where AinFRrepresents the area of the characteristic peak(s) of the corresponding chromatogram of the initial concentration of the FR component, A0Ut FRrepresents the area of the characteristic peak(s) of the corresponding chromatogram of the FR component after the adsorption treatment, minFRis the sample mass of the initial concentration of the FR component, and m0Ut FRis the sample mass of the FR component after adsorption treatment.

[0411] The results show that the waste XPS (from construction) used as insulation boards contains 2.85 ± 0.85 wt% of HBCD (determined from three measurements) and the pure XPS (insultation boards from DIY store) contains 0.85 ± 0.15 wt% of FR-122P (determined from three measurements), see Table 1.

[0412] Characterization of polymers in samples

[0413] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the pure polymer pellets as well as pure XPS and pure EPS were determined using gel permeation chromatography (GPC) calibrated to polystyrene standards. The polydispersity index was determined as PDI = Mw / Mn. The results are presented in Table 5.

[0414] SL24 / 75188PCINEOS Styrolution Group GmbH

[0415] 46

[0416] Table 5. Results of GPC measurements of selected polymers

[0417]

[0418] Solubility Testing for flame retardants

[0419] In a first screening, the solubility of the flame retardants HBCD and FR-122P in different solvents at 23 °C and at 50 °C was investigated by preparing mixtures of 0.1 wt.-%, 0.5 wt.-%, 1 wt.-% or 3 wt.-% of the respective flame retardant in different solvents, and stirring the mixtures for 24 h at the selected temperature.

[0420] After this, it was visually determined whether the flame retardant was dissolved. The results are presented in Tables 6 and 7.

[0421] Table 6. Solubility screening for HBCD (n.d. = not determined)

[0422]

[0423] * RED value relative to GPPS substantially above 1

[0424] Table 7. Solubility screening for FR-122P (n.d. = not determined)

[0425]

[0426] SL24 / 75188PCINEOS Styrolution Group GmbH

[0427] 47

[0428]

[0429] RED value relative to GPPS substantially above 1

[0430] In a second measurement, the solubility of flame retardants was determined quantitatively at 23 °C by the following procedure:

[0431] Preparation of excess solute (flame retardant) solutions at RT in closed vials with constant stirring for 24 h.

[0432] Centrifugation (4500 rpm, 20 minutes) of the suspension followed by the separation of the supernatant and drying of the sediment.

[0433] The amount of dissolved flame retardants was analyzed by a gravimetric method, including thermogravimetric analysis (TGA), which were performed in a Netsch TG 209 F3 Tarsus thermogravimeter. The runs were performed under a constant flow of dry nitrogen at a rate of 60 mL / min and the temperature profile was as follows: dynamic step from 35 to 250 °C at 15 °C / min, followed by an isothermal step at 250 °C for 15 minutes, dynamic step up to 600 °C at 100 °C / / min, followed by a dynamic step at 20 °C / min until 700 °C.

[0434] The results in Table 8 show that TPHP, TBBPA and HBCD dissolve in all solvents to some extent, FR-122P and DBDPE are not soluble in some of the solvents having an RED value relative to GPPS below 1. These solvents can be conveniently used to remove for instance FR-122P or DBDPE with a solid-liquid separation, e.g. by centrifugation or filtration.

[0435] Table 8 Solubility in wt.-% of flame retardants in solvents at 23 °C (n.d. = not determined)

[0436] >

[0437] >

[0438]

[0439] SL24 / 75188PCINEOS Styrolution Group GmbH

[0440] 48

[0441]

[0442] Particle Size Distribution of FR-122P and DBDPE

[0443] The particle size distributions of FR-122P and DBDPE were determined in cyclohexene. The procedure was the following:

[0444] Preparation of FR-122P suspensions in cyclohexene (0.5 wt% FR-122P) and DBDPE suspensions in butyl acetate (0.5 wt% DBDPE) at 23 °C with constant stirring in a closed vial.

[0445] The suspension was then immersed in an ultrasonic bath at 25 °C for 5 minutes before injecting it to a Malvern static laser diffraction particle size analyzer (Mastersizer S).

[0446] The results indicate that the particle size distribution of FR-122P is unimodal with particles in the range between 0.2 and 160 pm and DBDPE has a bimodal distribution with particles ranging from 0.19 to > 1000 pm. This information can be conveniently used, e.g. when selecting the pore size of the filter in solid / liquid separations.

[0447] FIG. 9 shows the particle size distributions of DBDPE (dashed line) and FR-122P (solid line) in cyclohexene.

[0448] Example 1

[0449] Pure XPS and pure EPS were mixed with different solvents. The dissolution of pure XPS and pure EPS resulted in turbid solutions, which indicated that insoluble particles were present. The amount of insoluble particles were quantified by performing centrifugation. The procedure was the following:

[0450] Preparation of 10 wt% solution in different solvents (cyclohexene, MEK, xylene, 2-pentanone).

[0451] Stirring for 90 min at 50 °C ± 2 °C.

[0452] Centrifugation performed in a Hermle Z 306 centrifuge (a swinging rotor type centrifuge) at 4000 rpm (10 min).

[0453] Separation of supernatant and sediment by decantation.

[0454] Drying at 60 °C (2 weeks).

[0455] Quantification of the % of sedimented particles by using gravimetric method.

[0456] SL24 / 75188PCINEOS Styrolution Group GmbH

[0457] 49

[0458] The results indicated that the separation of the insoluble particles from pure XPS and pure EPS is possible with centrifugation and pure XPS contained more insoluble particles (about 9 wt.-%) compared to pure EPS (about 2 wt.-%). The (originally beige) XPS sample provided a yellow supernatant, the (originally white) EPS provided a colorless supernatant. Table 9 shows the results in cyclohexene and xylene.

[0459] FIG. 10 shows a summary of the process.

[0460] Table 9. Results of centrifugation of insoluble particles

[0461]

[0462] Example 2

[0463] Based on the solubility tests above and particle size distribution analysis, the separation of FR-122P and DBDPE from the liquid phase was tested in cyclohexene using filtration.

[0464] The procedure was the following:

[0465] Preparation of a 0.5 wt.-% FR-122P or DBDPE suspension in cyclohexene and 4.75 wt.-% PS / 0.25 wt.-% FR-122P or DBDPE mixture in cyclohexene at 23 °C with constant stirring in closed vials.

[0466] Suspensions were placed in an ultrasonic bath for about 5 minutes.

[0467] Filtration was performed in a Sterlitech HP4750X cell, which was magnetically stirred at 500 rpm. This dead-end filtration setup was operated at 23 °C with a constant overpressure of 1.0 ± 0.1 bar. The volumetric flux was measured and both the feed and the filtrate were analyzed via TGA to determine the removal efficiency. In the case where PS was present in the filtrate, the turbidity calibration curve was used to quantify the removal efficiency. A commercialized PTFE membrane (0.1 pm) was used.

[0468] Next, the filtration was performed on a real waste sample coming from WEEE (WEEE Type 1 and WEEE Type 2, see Table 1). The procedure was the following:

[0469] Solutions of WEEE in cyclohexene (5 wt%) were prepared.

[0470] Filtration was performed in a Sterlitech HP4750X cell, with magnetic stirring at 500 rpm and 1.0 ± 0.1 bar overpressure at 23 °C.

[0471] The filtrate was analyzed with pyro-GC-MS.

[0472] SL24 / 75188PCINEOS Styrolution Group GmbH

[0473] 50

[0474] The results indicated that both FR-122P and DBDPE were successfully removed by filtration with a removal efficiency of 99.6 ± 0.2 wt.-% and 99.8 ± 0.1 wt.-% for PS / FR-122P-cyclohexene and PS / DBDPE-cyclohexene solutions, respectively. This while polystyrene can be recovered in the liquid phase (filtrate). A membrane with a pore filter size between 0.1 and 0.2 pm can be used to filter FR-122P and DBDPE. Finally, the filtration was performed on two real waste samples coming from WEEE containing FR-122P and a removal efficiency higher than 99% was obtained.

[0475] FIG. 11 shows a schematic (left) of the filtration process for polystyrene solutions containing FR-122P, where F is the filtrate and R is the retentate, and a graph (right) showing the filtration flux of cyclohexene mixtures of DBDPE (dashed line with triangles) and FR122P (solid line with asterisks) at a concentration of 0.5 wt.-%.

[0476] Example 3

[0477] Centrifugation was tested for the separation of FR-122P and DBDPE from the liquid phase. The procedure was the following:

[0478] Preparation of 0.5 wt.-% FR-122P or DBDPE suspension in cyclohexene and 4.75 wt.-% PS / 0.25 wt.-% FR-122P or 4.75 wt.-% PS / 0.25 wt.-% DBDPE in cyclohexene.

[0479] Centrifugation performed in a Hermle Z 306 centrifuge (a swinging rotor type centrifuge) at 4500 rpm (g-force of 3283 G) at different centrifugation times (1 , 5 and 10 min).

[0480] The density and the viscosity of the solutions were measured with an Anton Paar SVM 3001 viscometer at 20 °C.

[0481] Due to overlap in the TGA degradation peaks of DBDPE and FR-122P with PS, the removal efficiencies in this case were determined via turbidity measurements.

[0482] The results indicated that both FR-122P and DBDPE could be separated from the liquid phase with a removal efficiency of 99.9% (10 min centrifugation time). With a g-force of 3283 G, 99.9 % of FR-122P can be removed with 10 min centrifugation time, and DBDPE can be fully removed with less than 2 min centrifugation time.

[0483] Table 10 shows the sedimentation times required for 99% removal efficiency and 99.9% removal efficiency, as well as the cutting-off particle size after 1, 5 and 10 min.

[0484] Table 10. Sedimentation times and cutting-off particle sizes by centrifugation

[0485] SL24 / 75188PCINEOS Styrolution Group GmbH

[0486] 51

[0487]

[0488] The sedimentation velocity was calculated for 1 to 10 wt.-% polystyrene solutions containing FR-122P and DBDPE for the removal of the smallest particle of FR-122P (0.27 pm) and DBDPE (0.20 pm). The tubular bowl centrifuge is suitable to separate particles in the range of 0.1 and 100 pm in a small concentration of solids (<5 wt%) and can develop a g-force of up to 65,000 G. The minimum sedimentation velocity tabulated for a tubular bowl centrifuge with an inside diameter of 0.1 m and a value of 2508 m2operating at 13,200 G is 1.26-10'9m-s-1.

[0489] This indicates that FR-122P and DBDPE can be completely separated with a tubular bowl centrifuge operating at a g-force of 13200 G at RT (23 °C) from polystyrene solutions in the concentration range between 1 and 9 wt% for FR-122P and DBDPE or at 50 °C from polystyrene solutions with 10 wt% concentration for FR-122P.

[0490] Table 11. Sedimentation velocity for 1 to 10 wt% PS solutions at 25 and 50°C (n.d. = not determined)

[0491]

[0492] Example 4

[0493] Leaching of the soluble HBCD was performed in cyclohexane, which was shown to not dissolve polystyrene at 23 °C, by the following procedure:

[0494] Preparation of a 10 wt.-% waste XPS mixture in a closed vial.

[0495] Stirring the mixture constantly at 23 °C for 24 hours.

[0496] Centrifugation in a Hermle Z 306 centrifuge (a swinging rotor type centrifuge) at 4500 rpm for 20 min.

[0497] - Analysis of the liquid phase with pyro-GC-MS.

[0498] SL24 / 75188PCINEOS Styrolution Group GmbH

[0499] 52

[0500] The results have shown that up to 20 ± 3% of HBCD (based on the original amount of HBCD in the polymer) can be leached out from the polymer in one step (more can be leached out in multiple steps) with cyclohexane (for a 10 wt.-% polymer solution).

[0501] In sum, cyclohexane is able to leach out the HBCD and leave the FR-122P undissolved so that it can be removed by filtration / centrifugation after dissolving the polystyrene at elevated temperatures, followed by precipitation of the polystyrene at room temperature without the need for an antisolvent.

[0502] FIG. 12 shows a schematic of the leaching process described in Example 4.

[0503] Example 5

[0504] Batch adsorption experiments were performed on dissolved flame retardants HBCD, TBBPA and TPHP. The following procedure was implemented:

[0505] Preparation of 0.25 wt.-% flame retardant solutions in either cyclohexene or n- butyl acetate.

[0506] In a first iteration, no GPPS was added to the mixture, whereas in a second iteration 5.0 wt.-% GPPS was included for the most promising solvent / adsorbent combination.

[0507] For both iterations, solutions of 20 mL were prepared in glass vials with increasing adsorbent dose, specifying five different adsorbent concentrations of 1 , 5, 10, 15, and 25 g / L, where the three different adsorbent types AC-01 , AC-84 and AC- 87 were considered separately.

[0508] Prepared solutions were carefully sealed and shaken at 120 rpm at a temperature of 293 ± 1 K for at least 24 h.

[0509] Samples were subsequently filtered through a 0.45 pm PTFE membrane to separate the solid from the liquid phase.

[0510] The filtrate was analyzed via pyrolysis-GC-MS as described earlier. Comparing the solvents, it is apparent that cyclohexene performs significantly better than n-butyl acetate across all mixtures in terms of the flame retardant removal efficiency. For instance, at the maximal adsorbent dose of 25 g / L, 95 wt.-% of the HBCD in the solution was adsorbed by AC-84 in cyclohexene, while only approximately 60 wt.-% were adsorbed in n-butyl acetate.

[0511] From this it was concluded that solvents in which the solubility of the flame retardants was lower, resulted in improved adsorption efficiency compared with solvents, in which the solubility of the flame retardants is better (n-butyl acetate).

[0512] SL24 / 75188PCINEOS Styrolution Group GmbH

[0513] 53

[0514] Comparing the adsorbents, the highest removal efficiencies are obtained when treated with AC-84. For instance, a removal efficiency of 95 wt% is achieved for HBCD when treated with AC-84; whereas AC-01 and AC-87 performed worse with an average decrease in removal efficiency by 12 and 25 wt.-%, respectively.

[0515] FIG. 13 shows an overview of the adsorption results for the mixtures of HBCD (top), TBBPA (center) and TPHP (bottom) in both n-butyl acetate (left) and cyclohexene (right), without the addition of PS, using activated charcoals AC-01 (circles), AC-84 (squares) and AC-87 (triangles).

[0516] For the best solvent / adsorbent combination, being cyclohexene with AC-84, separate mixtures of the flame retardants were prepared with the addition of 5 wt% GPPS. In general, no significant changes in removal efficiency were observed, meaning that the measurements lay within the range defined by the standard deviation of the results without the addition of GPPS. This indicates that the dissolved GPPS does not compete with the dissolved flame retardants for the available adsorption sites.

[0517] FIG.14 shows the adsorption results for the mixtures of 5 wt.-% GPPS and 0.25 wt.-% of TBBPA (solid line with diamonds), HBCD (dashed line with circles) or TPHP (dotted line with triangles) in cyclohexene at a temperature of 293 ± 1 K, using AC-84 as the solid sorbent material SM.

[0518] Collectively, the results have shown that dissolved flame retardants, such as the flame retardants HBCD, TBBPA and TPHP can be removed from polymer solutions by means of adsorption in organic media.

[0519] Furthermore, the adsorption process in cyclohexene was also performed on two real waste samples coming from WEEE, containing TBBPA. At an adsorbent dose of 25 g / L, a removal efficiency higher than 90% was obtained.

[0520] Example 6

[0521] Next, batch adsorption was performed at 50 °C in cyclohexane with the adsorbent dose of 25g / L of AC-84 with and without the presence of AI2O3.

[0522] AI2O3 was added in a ratio of AI2O3 to AC-84 of 1 :1. The mixtures were left to stir for 24 h at 50 °C. The solutions were then centrifuged at 4000 rpm for 10 min and the supernatant was analyzed with pyro-GC-MS. In sum, activated charcoal with BET surfaces between 940 and 2000 m2 / g can be used to adsorb HBCD in a solvent in which HBCD has a solubility (at room temperature) between 1.1 and 9.5 wt.-%, preferably between SL24 / 75188PCINEOS Styrolution Group GmbH

[0523] 54

[0524] 3.1 and 9.5 wt.-% or between 1.1 and 3.1 wt.-%, more preferably about 1.1 wt.-%. The results in cyclohexane indicated that the presence of AI2O3 increased the adsorption of HBCD. In particular, with cyclohexane at 50 °C, 66 ± 7 wt.-% of HBCD were removed by batch adsorption using AC-84 alone, and more than 78 wt.-% of HBCD were removed when AC-84 was combined with AI2O3.

[0525] Example 7

[0526] Adsorption studies were conducted using a packed column. The following procedure was carried out:

[0527] Preparation of 5 wt.-% waste XPS solutions in cyclohexene were prepared. - AC-84 was sieved to obtain a 425 to 850 pm fraction.

[0528] - A column was filled with the best load obtained in the batch adsorption experiments, i.e. 25 g / L and with the best resulting activated charcoal (AC-84).

[0529] The solution was poured to the column and the effluent was collected over time. The effluent was analyzed for Br content with IC combustion.

[0530] The results indicated the HBCD was still present in the effluent, RE=69% (removal efficiency), indicating that higher loads of AC-84 are required.

[0531] Next the adsorption was also performed with a two-layer configuration, i.e. AI2O3 was added as a first layer and then activated charcoal (AC-84, 25g / L load) was added on top. The mass ratio of AI2O3 to AC-84 was 1:1. Similar as in Example 6, the column was filled with these two materials and then the waste XPS solution in cyclohexene (5 wt.-%) was poured to the column and the effluent was collected over time. The effluent was analyzed for Br content with IC combustion but also for PS content with TGA.

[0532] The results indicated that the two-layer configuration resulted in a slower adsorption but polystyrene was not retained. Additionally, AI2O3 substantially reduced the amount of charcoal in the filtrate, resulting in a clear filtrate (as compared to a turbid suspension without AI2O3). The results also indicated that the presence of AI2O3 reduced the amount of HBCD present in the effluent (as compared with the adsorption experiment without AI2O3), RE=83%.

[0533] Then, the adsorption column was filled completely with AC-84, which corresponds to a load of about 376 g / L, and the results showed that >99.99% of HBCD was removed. These results show that by combining the right amount of AC84 with AI2O3, HBCD can be completely removed and the charcoal can be retained, whilst polystyrene is recovered in the filtrate.

[0534] SL24 / 75188PCINEOS Styrolution Group GmbH

[0535] 55

[0536] Finally, adsorption studies were also performed on the pure XPS to check if the colorant could be adsorbed. The following procedure was carried out:

[0537] Preparation of 5 wt.-% pure XPS solutions in cyclohexene were prepared.

[0538] Filtration of the solution was performed with a 0.1 pm membrane at 2 bar overpressure, twice.

[0539] The filtrate was poured to the packed column, which was filled with AC-84 (425 to 850 pm fraction) and AI2O3 in a column height ratio of 1:1.

[0540] The filtrate was then subjected to a precipitation step with antisolvent to recover the polystyrene back.

[0541] The results showed that the colorant was successfully adsorbed when combining AC-84 with AI2O3 in a column height ratio of 1:1, the filtrate being entirely colorless. The results also confirmed that the charcoal could be retained whilst polystyrene is recovered in the filtrate.

[0542] FIG. 15 shows the column assembly and the filtrates obtained from 5 wt.-% solutions of waste XPS in cyclohexene, using 3 wt.-% of AC-84 alone having particles in the range of 425-850 pm.

[0543] FIG. 16 shows the column assembly and the filtrates when AC-84 is combined with AI2O3 under otherwise the same conditions.

[0544] FIG. 17 shows the column assembly and the filtrates using a column completely filled with AC-84 under otherwise the same conditions.

[0545] FIG. 18 shows the procedure performed for the adsorption of the yellowish colorant from pure XPS using AC-84 combined with AI2O3.

[0546] Example 8

[0547] Liquid-liquid extraction was performed for the removal of HBCD from dissolved polystyrene solutions. First, a solvent screening accompanied by relative solubilities of HBCD in the solvents as well as of polystyrene in the solvents was performed using computational tools (COnductor-like Screening MOdel for Realistic Solvents, COSMO-RS). Next, potential combinations of solvents that met the 3 criteria (RED relative to PS greater than 1.0; solubility of HBCD greater than in cyclohexene; mixtures of cyclohexene and the solvent S2 are heterogeneous if the amount of said solvent exceeds 10 wt.-%) for liquid-liquid-extraction were tested experimentally by the following the following procedure:

[0548] Preparation of solutions in cyclohexene (10 wt.-%) in a closed vial;

[0549] Stirring at 23 °C until the polymer is dissolved;

[0550] SL24 / 75188PCINEOS Styrolution Group GmbH

[0551] 56

[0552] - Adding the solution to a separating funnel, to which the extracting solvent was added in a ratio of 1:1 to the solution. The funnel was manually vigorously shaken and afterwards the separating funnel was left stir for at least 24 hours.

[0553] The two layers were then separated and analyzed with ion chromatography.

[0554] It was found that with DMSO the best removal efficiency from a cyclohexene solution is obtained. The results indicated that the upper layer contained the dissolved polystyrene and the bottom layer contained the DMSO and HBCD, showing that HBCD could be successfully extracted by liquid-liquid extraction with a removal efficiency of 96.4 ± 0.4%.

[0555] FIG. 19 shows a schematic of the method of Example 8.

[0556] The methods described in the Examples above and their removal efficiencies for different flame retardants are summarized in Table 12. Repetitions of individual steps or combi-nation of different steps can further improve the removal efficiency.

[0557] Table 12. Summary of methods for different flame retardants

[0558] >

[0559]

[0560] SL24 / 75188PCINEOS Styrolution Group GmbH

[0561] 57

[0562] >

[0563]

[0564] Example 9

[0565] Antisolvent precipitation was performed using different antisolvents (solvent component S4) at ratios of antisolvent : solvent of 5:1, as typically employed in the art, and 3:1. The procedure was as follows:

[0566] Preparation of 10 wt.-% polystyrene (GPPS 168 N) solutions in different solvents S1: cyclohexene (CH), methyl ethyl ketone (MEK), ethyl acetate (EA);

[0567] Addition of antisolvent S4 (4-methyl-2-pentanol, acetone, 2-propanol, distilled water, heptane, methanol, ethanol, pentane, dodecane) under different conditions of: addition order, addition rate, ratio of solvent : antisolvent, stirring speed, temperature);

[0568] It was found that at ratios of antisolvent : solvent of 3: 1 , similar results can be obtained as with the commonly employed ratio of 5:1, indicating a potential of reducing the amount of required antisolvent for precipitation. However, large gelly polystyrene lumps were observed in both cases, regardless of the solvent / antisolvent combination.

[0569] Continuous / batch-wise precipitation of the polystyrene solution to the antisolvent to control particle size was also tested. It was found that continuous or batchwise precipitation (using 4-5 batches) with continuous or batchwise withdrawal of precipitated polystyrene favored the formation of smaller particles (crystallization) and avoided large gelly polystyrene lumps. 74.2 to 80.8 wt.-% of polystyrene could be recovered by these methods.

[0570] FIG. 20 shows a comparison of the particles obtained from a one-step precipitation (left) and a batch-wise precipitation (right). In both cases, the amount of styrene recovered is between 80 and 81 wt.-%.

[0571] However, the batch-wise precipitation shows substantially finer particles.

[0572] Example 10

[0573] SL24 / 75188PCINEOS Styrolution Group GmbH

[0574] 58

[0575] To avoid the use of very large amounts of antisolvent and formation of gelly agglomerates, ternary diagrams were built and the use of a 3rdsolvent was tested. The procedure was the following:

[0576] Preparation of PS solutions in cyclohexene at different concentrations between 1 and 18 wt% in a thermostatic water bath at 25 °C. Ethanol was then added in fixed increments and before measuring the turbidity, the solution was left for 2 min in a ultrasonic bath to disperse the particles. The turbidity of the solution was monitored using a turbidimeter (model HI98703 by Hanna Instruments).

[0577] Next, the same procedure was repeated, but 1 wt% of DMSO was first added to all the prepared solutions (polystyrene-cyclohexene solutions) prior to adding ethanol. The ethanol was then added stepwise in fixed increments and the turbidity was monitored. The compositions of the solutions prior to adding ethanol are summarized in Table 13.

[0578] Table 13. Mixtures examined in Example 10

[0579]

[0580] The results showed that a 21 -fold lower antisolvent / solvent ratio than the one recommended in literature is sufficient to precipitate of polystyrene with the formation of fine particles, if a third solvent such as DMSO is present in amounts as low as 1 wt.-%.

[0581] FIG. 21 shows ternary diagrams for mixtures of polystyrene, cyclohexene (solvent) and ethanol (antisolvent) in the absence (top) and presence (bottom) of 1% by weight of DMSO. The dots indicate the mixtures at which precipitation occurred.

[0582] Additionally, the results also show that a solvent that successfully extracts HBCD (DMSO in this case) also helps the precipitation of polystyrene by increasing the polarity of the solution and consequently the required antisolvent / solvent ratio can go down by a factor of about 150 compared to the known procedures.

[0583] SL24 / 75188PCINEOS Styrolution Group GmbH

[0584] 59

[0585] Without being bound by theory, it is believed that the addition of a solvent such as DMSO with a RED value of 1.06 facilitates the precipitation of polystyrene since it increases the polarity of the solution (dielectric constant of cyclohexene is 2.22 and for a cyclohexene / 1 wt% DMSO mixture the dielectric constant increases to 2.85, which indicates that the polarity of the liquid phase increases, which likely facilitates the precipitation of PS).

[0586] Example 11

[0587] Steam precipitation was also tested as typically steam can be easily obtained in industry. Two experiments were conducted. The first one consisted of fully evaporating the solvent and in the other one only 78% of the solvent was evaporated. The procedure was the following:

[0588] Preparation of PS solutions in cyclohexene (10 wt%) and MEK (10 wt%);

[0589] Steam precipitation until polymer precipitated.

[0590] The results show that a complete evaporation of the solvent resulted in a block of polystyrene. By partially evaporating the solvent, a recovery yield of 98.8% was obtained and a gelly polystyrene agglomerate was obtained.

[0591] Example 12

[0592] Temperature-induced precipitation of polystyrene was performed in different solvents. The procedure was the following:

[0593] Preparation of PS solutions (10 wt%) in different solvents: cyclohexene, methyl ethyl ketone, ethyl acetate, cyclohexane;

[0594] The solutions were prepared at RT (23 °C) and placed in an ice bath or oil bath and the temperature inside the vials was monitored;

[0595] The turbidity change over temperature was visually monitored;

[0596] The results show that precipitation with the solvent that leads to successful leaching and separation of both flame retardants (in this case cyclohexane) also facilitates precipitation of polystyrene at 23 °C. The LICST diagram of PS-cyclohexane shows that the precipitation of PS occurs at approximately 27 °C (RED: 0.9) at different polystyrene concentrations. In cyclohexene, methyl ethyl ketone and ethyl acetate, temperature-induced precipitation was only observed below -4 °C.

[0597] FIG. 22 shows images of polystyrene in cyclohexane at different temperatures.

[0598] Example 13

[0599] SL24 / 75188PCINEOS Styrolution Group GmbH

[0600] 60

[0601] The precipitation of polystyrene (10 wt.-%) in cyclohexane was performed in a continuous crystallization reactor with a volume of 5 L. The dissolution reactor was at 31-32 °C and precipitation reactor was at 24 °C. Particle size was monitored when steady-state (constant temperature and volume in both reactors) was reached. With a residence time of 9 min, the precipitated polystyrene has a particle size distribution between 1 and 400 pm.

[0602] These results show that polystyrene can be precipitated at room temperature with finer particles compared to typical state of the art antisolvent precipitation and without the need of an antisolvent.

[0603] FIG. 23 shows a schematic visualization of the experimental assembly (top) and an image of the actual assembly used (bottom).

[0604] FIG. 24 shows the particle size distribution of three different samples of polystyrene obtained this way.

[0605] Example 14

[0606] Similar as for antisolvent precipitation, the effect of a co-solvent on the temperature induced precipitation was tested (reported in Table 14). The procedure was the following:

[0607] Dissolution of PS in cyclohexene, cyclohexane, butyl acetate or ethyl acetate, at about 10 wt% at RT in a closed vial.

[0608] Addition of a fixed amount of co-solvent and stirring for at least 1 h.

[0609] The solution were then placed either in an ice bath or in an oil bath to reach the desired temperature.

[0610] The temperature of the solution was monitored along with the turbidity. The latter was visually determined.

[0611] Table 14. Results of temperature-induced precipitation in the presence of a co-solvent.

[0612] <

[0613] <

[0614] <

[0615] <

[0616]

[0617] SL24 / 75188PCINEOS Styrolution Group GmbH

[0618] 61

[0619] <

[0620] <

[0621] <

[0622] <

[0623] <

[0624] <

[0625] <

[0626] <

[0627] <

[0628] <

[0629] <

[0630] <

[0631] <

[0632] <

[0633] <

[0634] <

[0635] <

[0636] <

[0637] <

[0638] <

[0639] <

[0640] <

[0641] <

[0642] <

[0643] <

[0644] <

[0645] <

[0646] <

[0647] <

[0648] <

[0649] <

[0650] <

[0651]

[0652] SL24 / 75188PCINEOS Styrolution Group GmbH

[0653] 62

[0654] The results indicate that in the presence of DMSO, a solvent that is good to extract HBCD with liquid / liquid extraction, the LICST of polystyrene in cyclohexene can be shifted to the temperature range between 1.8 and 80 °C above a certain value of polarity (dielectric constant higher than 3). This shows that an increase in the solvent mixture polarity shifts the LICST to higher temperatures and facilitates the precipitation of polystyrene.

[0655] Similar results were observed for other solvents, i.e. for solvents with RED value (between co-solvent and polymer) higher than 0.96 and dielectric constants for the mixture higher than 2.23 shift the LICST to temperatures between 0 °C and approximately 60 °C, facilitating polystyrene temperature-induced precipitation at room temperature (for example, cyclohexene / ethyl formate, cyclohexene / isobutyl isobutyrate, etc). Co-solvents that lead to mixtures with cyclohexene with dielectric constants higher than 3, like ethanol, DMSO, and NMP, lead to cloudy solutions at RT, with exception of methanol.

[0656] Example 15

[0657] Precipitation by solvent evaporation was tested by preparing a 10 wt.-% polystyrene solution in cyclohexene, pouring the solution into a petri-dish and drying for 3 days at 60 °C.

[0658] A polystyrene-film was obtained with a recovery yield of approximately 90%.

[0659] FIG. 25 shows the appearance of the polystyrene film.

[0660] Example 16

[0661] FIG. 26 discloses an apparatus 100 for recovery of polystyrene (PS) from polystyrene-containing waste (WPS) according to a first embodiment of the present invention, using cyclohexane as the solvent component S1.

[0662] In the process, the polystyrene waste is subjected to multiple stages:

[0663] Shredding: waste PS (WPS), as received, is fed to a shredder 110 in order to get smaller particles, e.g. between 1.0 and 2.36 mm;

[0664] Leaching: shredded waste PS and cyclohexane (S1) are fed to the leaching reactor 120 (temperature = 25 °C), where HBCD will be leached out from the swollen polystyrene and recovered in the liquid phase 10, and can be isolated, e.g. after drying in a dryer 190;

[0665] SL24 / 75188PCINEOS Styrolution Group GmbH

[0666] 63

[0667] Dissolution: swollen polymer is fed to a dissolution reactor 130 together with cyclohexane (temperature = 50°C), where PS will be dissolved;

[0668] Centrifugation: the dissolved PS is fed to a centrifuge 140 (temperature = 50°C) to separate a wet sediment 20 of insoluble particles 30 from the liquid phase. Insoluble particles 30 are for instance contaminants, the rubber particles from HIPS, and additives, which can be colorants, like TiCh but also flame retardants, e.g. FR-122P, which can be isolated, e.g. after drying in a dryer 190;

[0669] Filtration: this step is optional, but it is mostly to remove insoluble particles with smaller particle size 40, e.g. carbon black can be removed in this filtration step (temperature = 50°C), e.g. by feeding the supernatant from the centrifuge 140 into a filter 150, and can be isolated, e.g. after drying in a dryer 190;

[0670] Adsorption: this step is optional, but it is mostly to remove soluble contaminants (e.g. organic pigments or dyes but also (possible) traces of HBCD). The dissolved PS is fed to an adsorption column 160 (temperature = 50°C) containing activated charcoal (and AI2O3) that will adsorb the soluble contaminants;

[0671] Crystallization: the purified dissolved PS is fed to a crystallization reactor 170 (temperature = 25°C) where precipitation of PS will be induced by temperature. The recovered polystyrene is transferred to a dryer 190 whilst cyclohexane obtained in any of the steps can be reused in the system.

[0672] Example 17

[0673] FIG. 27 discloses an apparatus 200 for recovery of polystyrene from polystyrene-con-taining waste (WPS) according to a second embodiment of the present invention, using cyclohexene as the solvent component S1.

[0674] In the process, the polystyrene waste is subjected to multiple stages:

[0675] Shredding: waste PS (WPS), as received, is fed to a shredder 210 in order to get smaller particles, e.g. between 1.0 and 2.36 mm;

[0676] Dissolution: the shredded PS is fed to a dissolution reactor 230 together with cyclohexene (S1) (temperature = 25°C), where PS will be dissolved;

[0677] Centrifugation: the dissolved PS is fed to a centrifuge 240 (temperature = 25°C) to separate a wet sediment 20 of insoluble particles 30 from the liquid phase. Insoluble particles SL24 / 75188PCINEOS Styrolution Group GmbH

[0678] 64

[0679] 30 are for instance contaminants, the rubber particles from HIPS, and additives, which can be colorants, like TiO2 but also flame retardants, e.g. FR-122P, which can be isolated, e.g. after drying in a dryer 290;

[0680] Filtration: this step is optional, but it is mostly to remove insoluble particles with smaller particle size 40, e.g. carbon black can be removed in this filtration step (temperature = 25°C), e.g. by feeding the supernatant from the centrifuge 240 into a filter 250, and can be isolated, e.g. after drying in a dryer 290;

[0681] Adsorption: dissolved PS is fed to an adsorption column 260 (temperature = 25°C) containing activated charcoal (and AI2O3) so that soluble contaminants (e.g. organic pigments or dyes and HBCD) are adsorbed;

[0682] Precipitation: Precipitation of PS can be performed by steam precipitation, or by adding an antisolvent S4 (e.g. ethanol) or by freezing (e.g. T < - 4 °C) using appropriate precipitation means 280.

[0683] The recovered polystyrene is dried in a dryer 290 whilst the solvent(s) obtained in any step can be recovered e.g. by distillation and re-used in the process.

[0684] Example 18

[0685] FIG. 28 discloses an apparatus 300 for recovery of polystyrene (PS) from polystyrene-containing waste (WPS) according to a third embodiment of the present invention, using cyclohexene as the solvent component S1.

[0686] In the process, the polystyrene waste is subjected to multiple stages:

[0687] Shredding: waste PS (WPS), as received, is fed to a shredder 310 in order to get smaller particles, e.g. between 1.0 and 2.36 mm;

[0688] Dissolution: the shredded PS is fed to a dissolution reactor 330 together with cyclohexene (S1) (temperature = 25°C), where PS will be dissolved;

[0689] Centrifugation: the dissolved PS is fed to a centrifuge 340 (temperature = 25°C) to separate a wet sediment 20 of insoluble particles 30 from the liquid phase. Insoluble particles 30 are for instance contaminants, the rubber particles from HIPS, and additives, which can be colorants, like TiC>2 but also flame retardants, e.g. FR-122P, which can be isolated, e.g. after drying in a dryer 390;

[0690] SL24 / 75188PCINEOS Styrolution Group GmbH

[0691] 65

[0692] Filtration: this step is optional, but it is mostly to remove insoluble particles with smaller particle size 40, e.g. carbon black can be removed in this filtration step (temperature = 25°C), e.g. by feeding the supernatant from the centrifuge 340 into a filter 350, and can be isolated, e.g. after drying in a dryer 390;

[0693] Liquid-liquid extraction: The dissolved PS is fed to a liquid-liquid extraction column 370 (temperature = 25°C) which will use DMSO as solvent S2 to extract HBCD. HBCD is recovered in the heavy phase 50 in DMSO and can be isolated, e.g. after drying in a dryer 390, whilst polystyrene is recovered in the lighter phase 60 in cyclohexene;

[0694] Precipitation: The stream containing dissolved PS (and traces of DMSO) are fed to a precipitation vessel 380. The precipitation can occur with steam, by adding an antisolvent (e.g. ethanol) or by inducing with temperature (depending on the % of DMSO present in the feed). The recovered polystyrene is dried in a dryer 390 whilst the solvent(s) obtained in any step can be recovered e.g. by distillation and re-used in the process.

[0695] SL24 / 75188PC

Claims

INEOS Styrolution Group GmbH66Patent Claims1. A method of processing a polymer composition P, comprising the steps:a) mixing a polymer composition P, preferably comprising or consisting of post-consumer and / or post-industrial waste, comprisingA) a polymer A comprising repeating units of at least one aromatic vinyl monomer A1, preferably general purpose polystyrene and / or high impact polystyrene; andB) at least one additive B, preferably a colorant and / or flame retardant and / or stabilizer and / or processing agent, more preferably a flame retardant, more preferably a halogenated flame retardant;with a solvent component S1, to obtain a mixture M;b) subjecting the mixture M to conditions allowing separation of a fraction F1 comprising the polymer A from at least one fraction F2 comprising at least one additive B; andc) recovering a polymer composition P1 comprising the polymer A from fraction F1, wherein in the polymer composition P1 , the relative weight content of components that are not polymers comprising repeating units of aromatic vinyl monomer A1 is reduced by at least 50%, preferably at least 70% by weight, more preferably by at least 80% by weight, more preferably by at least 90% by weight, more preferably by at least 95% by weight, compared to the polymer composition P,wherein the RED value of the solvent component S1 relative to polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is in the range from 0.5 to <1;and wherein step b) comprises the following steps:b1) setting the temperature of the mixture M to a temperature Ti, which is equal to or greater than the upper critical solution temperature (LICST) of the polymer A in the solvent component S1 ; andb2) removing at least a portion of at least one additive B from the mixture M at the temperature Ti using at least one solid sorbent material SM or at least one solvent component S2, to obtain a fraction F1 comprising the polymer A and the solvent component S1 and a fraction F2 comprising the additive B and the solid sorbent material SM or the solvent component S2;wherein the solvent component S2 fulfils the following criteria (1), (2) and (3):(1) the RED value of the solvent component S2 relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is greater than 1.0; (2) the solubility of the additive B in the solvent component S2 at the temperature T 1 is greater than its solubility in solvent component S1 ; andSL24 / 75188EPINEOS Styrolution Group GmbH67(3) a mixture of the solvent component S1 and the solvent component S2 at the temperature Ti is heterogeneous, when the amount of the solvent component S2 exceeds 10% by weight, preferably exceeds 5% by weight, more preferably exceeds 1% by weight, more preferably exceeds 0.1% by weight, based on the total weight of the mixture of the solvent component S1 and the solvent component S2.

2. The method according to claim 1, wherein the at least one additive B comprises at least one additive B1 having a solubility in the solvent component S1 at the temperature Ti lower than 0.1% by weight, preferably lower than 0.01% by weight, more preferably lower than 1 ppm by weight, based on the total weight of a solution of the additive B1 alone in the solvent component S1, and step b) includes a solid-liquid separation step at temperature Ti, preferably centrifugation, filtration or a combination thereof, preferably between steps b1) and b2), wherein a solid fraction comprising the additive B1 is removed, forming part of the at least one fraction F2 comprising at least one additive B.

3. The method according to claim 1 or 2, wherein the at least one additive B comprises at least one additive B2 having a solubility in the solvent component S1 at a temperature T2, which is at least 5 °C below the LICST of the polymer A in the solvent component S1, of at least 1 ppm by weight, preferably at least 0.01% by weight, more preferably at least 0.1% by weight, based on the total weight of a solution of the additive B2 alone in the solvent component S1, and step b) includes a leaching step at temperature T2, preferably before step b1), wherein a liquid fraction comprising the additive B2 is removed, forming part of the at least one fraction F2 comprising at least one additive B.

4. The method according to any one of claims 1 to 3, wherein in step b2) at least a portion of the at least one additive B is removed from the mixture M using activated charcoal, preferably activated charcoal having a surface area of at least 500 m2 / g, more preferably at least 1000 m2 / g, more preferably at least 2000 m2 / g, as the at least one solid sorbent material SM,5. The method according to claim 4, wherein the solubility of at least one additive B alone in the solvent component S1 does not exceed 1% by weight, preferably 0.05% by weight, more preferably 0.02% by weight at temperature Ti.

6. The method according to claim 4 or 5, wherein the activated charcoal is used in combination with at least one aluminium oxide (AI2O3).

7. The method according to claim 6, wherein the mass-based AhC^charcoal ratio is from 0.5:1 to 2.5:1, more preferably from 0.6:1 to 0.8:1.SL24 / 75188PCINEOS Styrolution Group GmbH688. The method according to any one of claims 1 to 7, wherein the RED value of the solvent component S1 relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is in the range from 0.65 to 0.98, preferably from 0.7 to 0.95, more preferably from 0.72 to 0.93, more preferably from 0.89 to 0.91, wherein the temperature Ti is in the range from 30 to 80 °C, preferably 30 to 60 °C, and wherein the at least one sorbent material SM is used in step b2) for removing the at least one additive B from the mixture M1.

9. The method according to any one of claims 1 to 7, wherein the RED value of the solvent component S1 relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is in the range from 0.65 to 0.90, preferably from 0.71 to 0.80, more preferably from 0.73 to 0.77, and wherein the temperature Ti is in the range from 0 °C to 80 °C, preferably from 10 °C to 50 °C, more preferably from 15 °C to 30 °C.

10. The method according to any one of claims 1 to 9, wherein step c) comprises precipitation of the polymer composition P1 from the fraction F1 , comprising one or more of the following steps:c1) at temperature Ti, mixing the fraction F1 with a solvent component S3, which is preferably the same as solvent component S2, having an RED relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), in the range from 0.96 to 1.1, wherein the amount of solvent component S3 is in the range from 0.1 to 15% by weight, preferably in the range from 0.1 to 2% by weight, based on the total weight of the fraction F1 and the solvent component S3, and preferably wherein a mixture of the solvent component S1 and the solvent component S3 at the temperature Ti is homogeneous, when the amount of the solvent component S3 is 0.1 to 2% by weight, based on the total weight of the mixture of the solvent component S1 and the solvent component S3; andat the temperature Ti, mixing the mixture of fraction F1 and solvent component S3 with a solvent component S4 having a RED relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), of equal to or greater than 1.1, wherein the amount of solvent component S4 is greater than 0.4% by weight, preferably greater than 1 % by weight based on the total weight of the fraction F1 , the solvent component S3 and the solvent component S4, and preferably at least 10 times less, more preferably at least 20 times less, than the amount of solvent component S4 required for precipitation of the polymer A in the absence of solvent component S3, wherein a mixture of the solvent components S1 , S3 and S4 at the temperature Ti is homogeneous when the amount of solvent component S4 is within the specified range; orSL24 / 75188PCINEOS Styrolution Group GmbH69mixing solvent component S3 with solvent component S4 and then mixing the mixture of solvent components S3 and S4 with the fraction F1 under these conditions; c2) at temperature Ti, mixing the fraction F1 with a solvent component S5 having an RED relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), in the range from 0.75 to 2.1 , wherein the amount of solvent component S5 is in the range from 0.2 to 40% by weight, based on the total weight of the fraction F1 and the solvent component S5, wherein a mixture of the solvent component S1 and the solvent component S5 at the temperature Ti is homogeneous when the amount of solvent component S5 is within the specified range; and optionallycooling the mixture of the fraction F1 and the solvent component S5 from the temperature Ti to a temperature T3, wherein T3 is lower than Ti by at least 3 °C; c3) at temperature Ti, mixing with the fraction F1 a solvent component S4 having a RED relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), of equal to or greater than 1.1, wherein the amount of solvent component S4 is greater than 5% by weight, but less than 75% by weight, based on the total weight of solvent components S1 and S4, wherein a mixture of the solvent component S1 and solvent component S4 at the temperature Ti is homogeneous when the amount of solvent component S4 is within the specified range;c4) at temperature Ti, adding the fraction F1 to a solvent component S4 having a RED relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), of equal to or greater than 1.1, wherein the weight ratio of the total amount of fraction F1 to the total amount of solvent component S4 is in the range from 1:2 to 1:3, wherein the fraction F1 is added to the solvent component S4 continuously and simultaneously the precipitated polymer is removed continuously, or wherein the fraction F1 is added to the solvent component S4 batch-wise in batches of 1 :8 to 1:15 (weight ratio of F1 batches to S4), and the precipitated polymer is removed between the batches;c5) evaporating the solvent components in the fraction F1 at a temperature in the range from 28 °C to 100 °C and / or under subatmospheric pressure;c6) treating the fraction F1 with water vapor, thereby evaporating the solvent components in the fraction F1;c7) setting the temperature of the fraction F1 comprising the polymer A and the solvent component S1 to a temperature T2, which is at least 5 °C below the LICST of the polymer A in the solvent component S1.

11. The method according to claim any one of claims 1 to 10, wherein the polymer A comprises:A1) 40 to 100% by weight, preferably 50 to 99% by weight, more preferably 60 to 98% by weight, based on the total weight of polymer A, of repeating units SL24 / 75188PCINEOS Styrolution Group GmbH70of at least one aromatic vinyl monomer A1, preferably styrene, alpha-methyl styrene, p-methyl styrene, tert-butyl styrene, dimethyl styrene, aryl-halogen- ated styrene or mixtures thereof, more preferably styrene and / or alpha-methylstyrene, more preferably styrene;A2) 0 to 15%, preferably 0 to 10% by weight, more preferably 0 to 5% by weight, based on the total weight of the polymer A, of repeating units of at least one (meth)acrylonitrile and / or (meth) acrylate monomer A2;A3) 0 to 60% by weight, preferably 1 to 50% by weight, more preferably 2 to 40% by weight, based on the total weight of polymer A, of repeating units of at least one conjugated diene monomer A3, preferably butadiene or isoprene, more preferably butadiene; andA4) 0 to 30% by weight, preferably 0 to 15% by weight, more preferably 0 to 5% by weight, based on the total weight of the polymer A, of units of cross-linking agents and / or further monomers copolymerizable with A1 , A2 and A3.

12. The method according to any one of claims 1 to 11, wherein the polymer A comprises repeating units of the at least one aromatic vinyl monomer A1 and optionally of at least one (meth)acrylonitrile and / or (meth)acrylate monomer A2 grafted to at least one rubbery core, preferably at least one rubbery core comprising repeating units of at least one conjugated diene monomer A3 and optionally at least one monomer A1 and / or A2, and optionally cross-linking agents and / or further monomers copolymerizable with A3.

13. The method according to any one of claims 1 to 12, wherein the polymer composition P comprises:A) 60 to 99.9% by weight, based on the total weight of the polymer composition P, of one or more polymers A, preferably comprising general purpose polystyrene and / or high impact polystyrene;B) 0.1 to 30% by weight, based on the total weight of the polymer composition P, of one or more additives B, preferably comprising at least one flame retardant and optionally one or more pigments, dyes, fillers, plasticizers, stabilizers and lubricants;C) 0 to 30% by weight, based on the total weight of the polymer composition P, of one or more polymers C not containing any repeating units of at least one aromatic vinyl monomer A1; andD) 0 to 30% by weight of contaminants such as organic residues, dirt, metals, paper and moisture.

14. The method according to any one of claims 1 to 13, wherein the method comprises one or more steps selected from:washing the polymer composition P to remove contaminants;SL24 / 75188PCINEOS Styrolution Group GmbH71drying the polymer composition P after removing the contaminants; and comminution of the polymer composition P to reduce particle size, preferably before step a).

15. The method according to any one of claims 1 to 14, comprising the steps: a) mixing a polymer composition P, preferably post-consumer and / or post-industrial waste, comprisingA) a polymer A comprising mainly general purpose polystyrene and / or high-im- pact polystyrene; andB) at least one additive B, comprising at least one flame retardant selected from brominated or phosphorous-containing hydrocarbons, preferably hexabromocyclododecane (HBCD) tetrabromobisphenol A (TBBPA), triphenyl phosphate, decabromodiphenyl ethane (DBDPE) and / or polybrominated styrenebutadiene copolymers;with a solvent component S1, to obtain a mixture M;b) subjecting the mixture M to conditions allowing separation of a fraction F1 comprising the polymer A from at least one fraction F2 comprising at least one flame retardant; andc) recovering a polymer composition P1 , mainly comprising the polymer A from fraction F1,wherein the solvent component S1 is cyclohexane;wherein step b) comprises the following steps:ba) optionally, at a temperature T2 which is at least 5 °C below the LICST of the polymer A in cyclohexane, leaching at least a portion of the at least one additive B from the polymer composition P using cyclohexane, to remove a liquid fraction comprising at least a portion of at least one additive B, forming part of the at least one fraction F2;bb) setting the temperature of the mixture M to a temperature T1 in the range from 30 to 80 °C, preferably from 30 to 60 °C;be) optionally subjecting the mixture M to filtration, centrifugation or a combination thereof, to remove a solid fraction comprising at least a portion of at least one additive B, forming part of the at least one fraction F2; andbd) removing the additive B from the mixture M at the temperature T1 using activated charcoal ora combination thereof with aluminium oxide, to obtain a fraction F1 comprising the polymer A and the solvent component S1 and a fraction F2 comprising the additive B and the solid sorbent material.

16. The method according to any one of claims 1 to 14, comprising the steps: a) mixing a polymer composition P, preferably post-consumer and / or post-industrial waste, comprisingSL24 / 75188PCINEOS Styrolution Group GmbH72A) a polymer A comprising mainly general purpose polystyrene and / or high-im- pact polystyrene; andB) at least one additive B selected from brominated or phosphorous-containing hydrocarbons, preferably hexabromocyclododecane (HBCD) tetrabromobisphenol A (TBBPA), triphenyl phosphate, decabromodiphenyl ethane (DBDPE) and / or polybrominated styrene-butadiene copolymers; with a solvent component S1 , to obtain a mixture M;b) subjecting the mixture M to conditions allowing separation of a fraction F1 , mainly comprising the polymer A from at least one fraction F2 comprising at least one flame retardant; andc) recovering a polymer composition P1 comprising the polymer A from fraction F1, wherein the solvent component S1 is cyclohexene;wherein step b) comprises the following steps:be) setting the temperature of the mixture M to a temperature Ti in the range from 0 to 29 °C, preferably from 15 to 27 °C;bf) optionally subjecting the mixture M to filtration, centrifugation or a combination thereof, to remove a solid fraction comprising at least a portion of at least one additive B, forming part of the at least one fraction F2; andbg) removing the additive B from the mixture M at the temperature Ti using activated charcoal or a combination thereof with aluminium oxide as the solid sorbent material SM or dimethyl sulfoxide as at least one solvent component S2, to obtain a fraction F1 comprising the polymer A and the solvent component S1 and a fraction F2 comprising the additive B and the solid sorbent material SM or the solvent component S2.

17. A method of processing a polymer composition P, preferably a method according to any one of claims 1 to 16, comprising the steps:a) mixing a polymer composition P, preferably comprising or consisting of post-consumer and / or post-industrial waste, comprisingA) a polymer A comprising repeating units of at least one aromatic vinyl monomer A1, preferably general purpose polystyrene and / or high impact polystyrene; andB) at least one additive B, preferably a colorant and / or flame retardant and / or stabilizer and / or processing agent, more preferably a flame retardant, more preferably a halogenated flame retardant;with a solvent component S1, to obtain a mixture M;b) subjecting the mixture M to conditions allowing separation of a fraction F1 comprising the polymer A from at least one fraction F2 comprising at least one additive B; andSL24 / 75188PCINEOS Styrolution Group GmbH73c) recovering a polymer composition P1 comprising the polymer A from fraction F1, wherein in the polymer composition P1 , the relative weight content of components that are not polymers comprising repeating units of aromatic vinyl monomer A1 is reduced by at least 50%, preferably at least 70% by weight, more preferably by at least 80% by weight, more preferably by at least 90% by weight, more preferably by at least 95% by weight, compared to the polymer composition P, wherein the RED value of the solvent component S1 relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is in the range from 0.5 to <1; and wherein step c) comprises one or more of the steps c1), c2), c3) and c4) as defined in claim 10.

18. A method of processing a polymer composition P, preferably a method according to any one of claims 1 to 17, comprising the steps:a) mixing a polymer composition P, preferably comprising or consisting of post-consumer and / or post-industrial waste, comprisingA) a polymer A comprising repeating units of at least one aromatic vinyl monomer A1, preferably general purpose polystyrene and / or high impact polystyrene; andB) at least one additive B, preferably a colorant and / or flame retardant and / or stabilizer and / or processing agent, more preferably a flame retardant, more preferably a halogenated flame retardant;with a solvent component S1, to obtain a mixture M;b) subjecting the mixture M to conditions allowing separation of a fraction F1 comprising the polymer A from at least one fraction F2 comprising at least one additive B; andc) recovering a polymer composition P1 comprising the polymer A from fraction F1, wherein in the polymer composition P1 , the relative weight content of components that are not polymers comprising repeating units of aromatic vinyl monomer A1 is reduced by at least 50%, preferably at least 70% by weight, more preferably by at least 80% by weight, more preferably by at least 90% by weight, more preferably by at least 95% by weight, compared to the polymer composition P, wherein the RED value of the solvent component S1 relative to the polymer A, determined via Hansen Solubility Parameters at 25 °C (HSP), is in the range from 0.86 to 0.95; andwherein step b) comprises the following steps:bg) at a temperature T2 which is at least 5 °C below the LICST of the polymer A in the solvent component S1, preferably between 0°C and 27 °C, leaching at least a portion of the at least one additive B from the polymer composition P using the solvent component S1 , to remove a liquid fraction comprising at least a portion of at least one additive B, forming part of the at least one fraction F2; SL24 / 75188PCINEOS Styrolution Group GmbH74bh) setting the temperature of the mixture M to a temperature Ti that is equal to or greater than the LICST of the polymer A in the solvent component S1 , preferably in the range from 30 to 80 °C, more preferably from 30 to 60 °C; and bi) subjecting the mixture M to filtration, centrifugation or a combination thereof, to remove a solid fraction comprising insoluble particles; andwherein step c) comprises cooling the fraction F1 obtained in step b) to a temperature T2 which is at least 5 °C below the LICST of the polymer A in the solvent component S1 , preferably between 0°C and 27 °C, to precipitate the polymer composition P1.

19. A polymer composition P1 obtained by the method of processing according to any one of claims 1 to 18, comprising general purpose polystyrene and / or high impact polystyrene as polymer A, and having a content of the at least one additive B below 0.5% by weight, preferably below 0.01% by weight, more preferably from 1 ppb to 1 ppm by weight, based on the total weight of the polymer composition P1.SL24 / 75188PC

Images