Dissolution recycling of colored thermoplastic polymer compositions

Abstract

The invention is directed at a method of processing a colored thermoplastic polymer composition, which allows separation of individual polymer components and colorant components, a thermoplastic polymer composition obtained by said method, and a molded article comprising the thermoplastic polymer composition.

Description

[0001] Dissolution recycling of colored thermoplastic polymer compositions

[0002] Description

[0003] The invention is directed at a method of processing a colored thermoplastic polymer composition, which allows separation of individual polymer components and colorant components, a thermoplastic polymer composition obtained by said method, and a molded article comprising the thermoplastic polymer composition.

[0004] Polymer products are omnipresent and find applications in most 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 produced on a million ton scale worldwide. However, the 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.

[0005] 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 were made to develop processes for the recovery of raw materials from plastics, such as post-consumer goods and post-industrial goods. Many of these 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.

[0006] Solvent-based recycling methods are one type of means for retrieving raw materials from polymer waste and essentially involve partial dissolution of polymer waste and separation of the dissolved components from insoluble components. Known methods for sol- vent-based recycling are described in the following.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] S. Ordonselli et al. (Manufacturing Letters 35, pp 1293-1302 (2023)) report about the removal of carbon black pigments from ABS polymer solutions, using so-called “collector solvents” (e.g. water or ethylene glycol). Result is a largely density related, yet incomplete multi-phase system, with carbon black being in the “Collector solvent” water, as well as in another phase, together with ABS and solvent.

[0017] The authors describe a middle phase of 8 % (in this case of ethyl acetate solution) in the “collector solvent” water. They propose to improve phase-separation by variation of temperature and concentration of ABS in the solvent.

[0018] Rubber-reinforced thermoplastic compositions, such as those based on acrylonitrile-bu- tadiene-styrene graft copolymers (ABS) oracrylonitrile-styrene-acrylate graft copolymers (ASA) are important thermoplastic materials with desirable properties, such as high impact strength, processability and surface appearance of the manufactured articles.

[0019] Such compositions typically contain graft copolymer particles, with a core made of a rubbery polymer, onto which polymer chains are grafted, which are embedded in a thermoplastic polymer matrix.

[0020] Due to the good properties of rubber-reinforced thermoplastic compositions, these materials are used in a large variety of consumer and industrial goods, such as in automotive parts, household appliances, toys, etc., which are often produced in different colors and with different additives that are selected based on the particular requirements of the manufactured products. However, due to the complex structure of the materials, recycling rubber-reinforced thermoplastic compositions is often difficult using known solventbased recycling methods. Especially in the case of colored waste products based on rubber-reinforced thermoplastic compositions, it is desirable to remove as much of the colorants and additives as possible, in order to avoid unfavorable coloration of products prepared from the recycled raw materials.

[0021] It has now surprisingly been found that colored and / or otherwise additive-containing rubber-reinforced thermoplastic compositions, such as those based on acrylonitrile-butadi- ene-styrene graft copolymers or acrylonitrile styrene-acrylate graft copolymers can be effectively separated into polymeric components, additives (such as colorants) and optionally further components, if subjected to a specific process as described herein.

[0022] One aspect of the present invention is a method of processing a thermoplastic polymer composition T, comprising the steps: a) mixing a thermoplastic polymer composition T, preferably post-consumer and / or postindustrial waste, comprising

[0023] A) at least one copolymer A comprising:

[0024] A1) repeating units of at least one aromatic vinyl monomer A1 , preferably styrene, alphamethyl styrene and / or p-methylstyrene, more preferably styrene; A2) repeating units of at least one vinyl cyanide monomer A2, preferably acrylonitrile and / or methacrylonitrile, more preferably acrylonitrile; and

[0025] A3) optionally repeating units of one or more further monomers A3 which are co-polymer- izable with A1 and / or A2;

[0026] B) at least one graft copolymer B comprising:

[0027] B1) a rubbery core B1 obtained by polymerizing

[0028] B11) at least 60% by weight, based on the total weight of the rubbery core B1 , of at least one conjugated diene and / or alkyl(meth)acrylate monomer B11 , preferably butadiene, isoprene, butyl acrylate monomer and / or ethylhexyl acrylate monomer, more preferably butadiene and / or butyl acrylate, more preferably butadiene;

[0029] B12) optionally up to 40% by weight, based on the total weight of the rubbery core B1 , of monomers B12 copolymerizable with the conjugated diene and / or alkyl(meth)acrylate monomer B11 , preferably at least one aromatic vinyl monomer (A1) and / or at least one vinyl cyanide monomer (A2);

[0030] B13) optionally up to 5% by weight, based on the total weight of the rubbery core B1 , of at least one cross-linking agent, preferably dicyclopentadienyl acrylate, tris-allyl isocy- anurate, ethylene glycol di(meth)acrylate and / or allyl(meth)acrylate; and optionally

[0031] B2) a rubbery core B2 different from rubbery core B1 , preferably selected from silicone rubber and / or EPDM rubber; and

[0032] B3) a polymeric shell B3, grafted to the rubbery core B1 and optionally the rubbery core B2, comprising

[0033] B31) repeating units of at least one aromatic vinyl monomer A1 ; and / or

[0034] B32) repeating units of at least one vinyl cyanide monomer A2;

[0035] C) at least one additive C from the group of colorants and flame retardants, more preferably at least one colorant, which is at least one pigment or dye; and

[0036] D) optionally one or more further components D different from A, B and C, preferably selected from the group comprising

[0037] D1) further polymers D1 ;

[0038] D2) further additives D2 and

[0039] D3) contaminants D3, such as organic residues, dirt, metals, paper and moisture; with at least one solvent component S, to obtain a mixture T1 and optionally a swollen and / or insoluble fraction T2; b) at least partially separating the swollen and / or insoluble fraction T2, if present, from the mixture T1 , preferably by gravimetric separation, filtration or a combination thereof, more preferably by gravimetric separation; c) at least partially separating soluble additives C1 and optionally further soluble components D-1 from the at least one copolymer A in mixture T 1 ; d) isolating a polymer composition T3 from the mixture T1 , preferably by removing solvent from the mixture T 1 obtained in step c); e) optionally isolating a polymer composition T4, preferably colored polymer composition T4 from the swollen and / or insoluble fraction T2, f) optionally further processing of the polymer composition T3 and / or the polymer composition T4, preferably by drying, washing, extrusion and / or calendering; wherein the polymer composition T3 comprises not more than 50% by weight, preferably not more than 20% by weight, more preferably not more than 10% by weight of the components C and D present in the thermoplastic composition T, based on the total weight of components C and D.

[0040] In the context of the present invention, a component is considered insoluble in a specific solvent at a specific temperature (preferably 23 °C, if not stated otherwise), if at least 90%, preferably at least 95% of the component remain undissolved in the solvent, when a 10 g / L mixture of the component with the solvent is prepared by stirring for a duration of 24 hours.

[0041] Another aspect of the present invention is a thermoplastic polymer composition obtained by said method, wherein the polymer composition is the polymer composition T3, the polymer composition T4, a mixture thereof, or a mixture of T3, T4 or both with virgin material.

[0042] Yet another aspect of the present invention is a molded article comprising said thermoplastic polymer composition, and the use of said polymer composition for the preparation of a molded article.

[0043] In a specific embodiment of the invention, a collector solvent is added to the mixture of the thermoplastic polymer composition T and the solvent component S, in order to remove unwanted components, which could be organic and / or inorganic substances, for example dispersed particles, preferably insoluble additives C2, more preferably insoluble colorants, more preferably carbon black, while the solubility of the solvent phase containing the thermoplastic polymer component T in the collector solvent is less than 5 %. Collector solvents can be any liquids that show a phase separation to the solvent phase containing the thermoplastic polymer component T. Examples are: water, ethylene glycol and other polar liquids, as they interact with carbon black which is oxidized and carries e.g. polar COOH, OH-functions on the surface.

[0044] Preferably, the collector solvent is a solution comprising a polar liquid, such as water or ethylene glycol, preferably water, and a base, such as an alkali metal hydroxide or an earth alkali metal hydroxide, and optionally a surfactant or a surfactant mixture. More preferably, the collector solvent is a solution comprising water and an alkali metal hydroxide, preferably sodium hydroxide or potassium hydroxide, more preferably sodium hydroxide, and optionally a surfactant or a surfactant mixture. More preferably, the collector solvent comprises water, sodium hydroxide and a surfactant or a surfactant mixture. Preferably, the concentration of the base in the collector solvent is in the range from 0.01 to 5% by weight, more preferably from 0.1 to 2% by weight, more preferably from 1 to 1 .5% by weight, based on the total weight of the collector solvent. Preferably, the concentration of surfactant or surfactant mixture in the collector solvent is in the range of from 0.01 to 3% by weight, preferably from 0.015 to 2% by weight, more preferably from 0.02 to 1.5% by weight, based on the total weight of the collector solvent. It has been surprisingly found that collector solvents comprising a base and a surfactant effectively facilitate removal of carbon black from mixtures of the thermoplastic polymer composition T and the solvent component S.

[0045] Preferably, the collector solvent is added to a mixture of the thermoplastic polymer component T and the at least one solvent component S, where the concentration of the thermoplastic polymer component T, based on the total weight of the mixture, is in the range from 0.01 to 5% by weight, preferably from 0.1 to 4% by weight, more preferably from 0.5 to 3% by weight, more preferably from 1 to 2.5% by weight. Preferably, the volume ratio of the collector solvent to the mixture of the thermoplastic polymer component T and the at least one solvent component S is in the range of from 0.1 :1 to 10:1 , more preferably from 0.2:1 to 5:1 , more preferably from 0.5:1 to 3:1 , more preferably from 1 :1 to 2:1.

[0046] The thermoplastic polymer composition T, which is preferably obtained from post-consumer and / or post-industrial waste, and is also referred to as an additivated thermoplastic polymer composition T, comprises at least one copolymer A, at least one graft copolymer B and at least one additive C, and may optionally comprise further components D different from A, B and C, such as further polymers D1 , further additives D2 and contaminants D3.

[0047] The at least one copolymer A may be any copolymer or mixture of copolymers comprising repeating units of at least one aromatic vinyl monomer A1 , preferably styrene, alphamethyl styrene and / or p-methylstyrene, more preferably styrene, and repeating units of at least one vinyl cyanide monomer A2, preferably acrylonitrile and / or methacrylonitrile, more preferably acrylonitrile. Moreover, the copolymer A may optionally comprise repeating units of further monomers A3 that are co-polymerizable with the at least one aromatic vinyl monomer A1 and / or the at least one vinyl cyanide monomer A2. Exemplary further monomers A3 include olefins, such as ethylene and Ca-Cs alpha-olefins, conjugated diene monomers such as butadiene or isoprene, (meth)acrylic monomers, such as acrylic acid, methacrylic acid and esters thereof with Ci-Cs alcohols, functionalized monomers such as maleic anhydride, and other ethylenically unsaturated monomers.

[0048] In the context of the present invention, a repeating unit of a specific monomer refers to the structural unit within a polymer chain that is obtained during polymerization of the respective monomer. The expression does not imply that any specific number of consecutive repetitions of the unit must be present within a polymer. Accordingly, a polymer comprising repeating units of specific monomers can be understood as a polymer obtained by polymerization of these monomers. The term “polymer” includes both homopolymers, which contain only a single type of repeating unit, and copolymers, which contain two or more types of repeating units.

[0049] Preferably, the at least one copolymer A comprises at least one styrene-acrylonitrile copolymer (SAN) optionally containing repeating units of further monomers A3. More preferably, the SAN copolymer has a weight average molecular weight Mw (determined by gel permeation chromatography calibrated to polystyrene standards) in the range from 50.000 to 500.000 g / mol, preferably from 100.000 to 250.000 g / mol, more preferably from 150.000 to 200.000 g / mol. More preferably, the SAN copolymer has a polydispersity index Mw / Mn (determined by gel permeation chromatography calibrated to polystyrene standards) in the range from 1 .5 to 5.0, preferably from 1 .8 to 3.5, more preferably from 2.0 to 3.0.

[0050] Preferably, the at least one copolymer A comprises from 40 to 99% by weight, preferably from 50 to 90% by weight, more preferably from 60 to 80% by weight, more preferably 65 to 75% by weight, based on the total weight of the at least one copolymer A, of the repeating units of at least one aromatic vinyl monomer A1 ; 1 to 60% by weight, preferably 10 to 50% by weight, more preferably 20 to 40% by weight, more preferably 25 to 35% by weight, based on the total weight of copolymer A, of the repeating units of at least one vinyl cyanide monomer A2; and 0 to 59% by weight, preferably 0 to 40% by weight, more preferably 0 to 20% by weight, more preferably 0 to 10% by weight, based on the total weight of copolymer A, of the further monomers A3 copolymerizable with A1 and / or A2.

[0051] The at least one graft copolymer B may be any graft copolymer or mixture of graft copolymers comprising a rubbery core and a polymeric shell B3 comprising repeating units of at least one aromatic vinyl monomer A1 and / or repeating units of at least one vinyl cyanide monomer A2 grafted to the rubbery core. Moreover, the polymeric shell B3 may optionally comprise repeating units of further monomers A3 that are co-polymerizable with the at least one aromatic vinyl monomer A1 and / or the at least one vinyl cyanide monomer A2. The at least one aromatic vinyl monomer A1 , the at least one vinyl cyanide monomer A2 and optionally further monomers A3 present in the polymeric shell B3 can be selected from those described above in the context of the at least one copolymer A, and may be the same as, or different from those in the at least one copolymer A. Preferably, the polymeric shell B3 comprises polystyrene and / or styrene-acrylonitrile copolymer (SAN), more preferably at least one styrene-acrylonitrile copolymer.

[0052] Preferably, the polymeric shell B3 comprises 40 to 100% by weight, preferably 50 to 90% by weight, more preferably 60 to 80% by weight, more preferably 65 to 75% by weight, based on the total weight of the polymeric shell B3, of the repeating units of at least one aromatic vinyl monomer A1 and 0 to 60% by weight, preferably 10 to 50% by weight, more preferably 20 to 40% by weight, more preferably 25 to 35% by weight, based on the total weight of the polymeric shell B3, of the repeating units of at least one vinyl cyanide monomer A2. More preferably, the polymeric shell B3 does not comprise repeating units of monomers other than A1 and A2.

[0053] The rubbery core, to which the polymeric shell B3 is grafted, can be a rubbery core B1 obtained by polymerising at least 60% by weight, preferably at least 70 to 99.8% by weight, more preferably 80 to 90% by weight, based on the total weight of the rubbery core B1 , of at least one conjugated diene and / or alkyl(meth)acrylate monomer B11 , optionally up to 40% by weight, preferably 0 to 29.9% by weight, more preferably 9.5 to 19.5% by weight, based on the total weight of the rubbery core B1 , of monomers B12 copolymerizable with the conjugated diene and / or alkyl(meth)acrylate monomer B11 , and optionally up to to 5% by weight, preferably 0.2 to 4% by weight, more preferably 0.5 to 3% by weight, based on the total weight of the rubbery core B1 , of at least one cross-linking agent B13. Where the monomer B11 is not a conjugated diene, the amount of cross-linking agent B13 is at least 0.1 % by weight, based on the total weight of the rubbery core B1 .

[0054] The conjugated diene and / or alkyl(meth)acrylate monomer B11 of the rubbery core B1 is preferably butadiene, isoprene, butyl acrylate and / or ethylhexyl acrylate, more preferably butadiene and / or butyl acrylate, more preferably butadiene.

[0055] Preferable optional monomers B12 copolymerizable with the conjugated diene and / or alkyl(meth)acrylate monomer B11 are aromatic vinyl monomers A1 and / or vinyl cyanide monomers A2, such as those described above in the context of the at least one copolymer A, and may be the same as, or different from those in the at least one copolymer A and / or in the polymeric shell B3. Preferably, the optional monomers B12 comprise styrene, acrylonitrile or a mixture thereof. Preferably, the optional monomers B12 do not comprise repeating units of monomers other than A1 and A2. Preferable crosslinking agents B13 include dicyclopentadienyl acrylate, tris-allyl isocyanurate, ethylene glycol di(meth)acrylate and / or allyl(meth)acrylate.

[0056] The at least one graft copolymer B may optionally contain a rubbery core B2, which is different from rubbery core B1. Preferably, the rubbery core B2 contains silicone rubber and / or ethylene propylene diene monomer (EPDM) rubber.

[0057] Preferably, the at least one graft copolymer B comprises a rubbery core B1 with a polymeric shell B3 grafted thereto, and optionally a rubbery core B2 with a polymeric shell B3 grafted thereto. More preferably, the at least one graft copolymer B is an ABS graft copolymer, an ASA graft copolymer, or a mixture thereof, more preferably an ABS graft copolymer.

[0058] Preferably, the at least one graft copolymer B comprises 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 30 to 70% by weight, based on the total weight of the graft copolymer B, of the rubbery core B1 , and 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 30 to 70% by weight, based on the total weight of graft copolymer B, of the polymeric shell B3 grafted on the rubbery core B1.

[0059] The thermoplastic polymer composition T comprises at least one additive C from the group of colorants and flame retardants, more preferably at least one colorant which is at least one pigment, at least one dye or a mixture of at least one pigment and at least one dye. Preferably, the additive C comprises at least one pigment, or a mixture thereof with at least one dye. The colorant may contain any pigment or dye known in the art that is suitable for, or used for coloration of thermoplastic polymer compositions, such as ABS graft copolymer compositions and ASA graft copolymer compositions.

[0060] For example, the colorant may be selected from inorganic and / or organic dyes and / or pigments. Examples for suitable dyes include any dyes that may be used for transparent, semi-transparent, or non-transparent coloring of thermoplastic polymer compositions, such as red dyes, green dyes, blue dyes, yellow dyes, magenta dyes, cyan dyes or any other color of dyes. Suitable dyes include, among others, Solvent Green, Solvent Violet, Solvent Red, Solvent Yellow, e.g. Solvent Green 3, Solvent Red 179, Solvent Yellow 93. Examples for suitable pigments include titanium dioxide, phthalo-cyanines, ultramarine blue, iron oxides, carbon black, and the entire class of organic pigments.

[0061] Examples of suitable flame retardants that may be used include the halogen-containing or phosphorus-containing compounds known to the person skilled in the art, magnesium hydroxide, and also other commonly used compounds, or mixtures thereof. These often are combined with synergists, such as antimony(lll)oxide. Preferable flame retardants are halogenated flame retardants, such as tetrabromobisphenol A, and are preferably used in combination with synergists such as antimony(lll)oxide.

[0062] It has surprisingly been found that flame retardants, such as halogenated flame retardants, are particularly effectively removed by the method of the invention from the mixture T1.

[0063] Furthermore, the thermoplastic polymer composition T may optionally comprise further components D different from A, B and C, such as further polymers D1 , further additives D2 and contaminants D3 such as organic residues, dirt, metals, paper and moisture.

[0064] Further polymers D1 that may optionally be present in the thermoplastic polymer composition T may be any polymers that do not fall within the definition of the at least one copolymer A or the at least one graft copolymer B, and that can be used in products in combination with the at least one copolymer A or the at least one graft copolymer B. For example, further polymers D1 may contain, e.g., homopolymers of the at least one vinyl monomer A1 , the at least one vinyl cyanide monomer A2 and / or further monomers A3, or copolymers of either one of A1 or A2 with further monomers A3; polyesters; polycarbonates; polyamides; polyethers; polyurethanes; phenyl formaldehyde resins; compati- bilizing polymers; and polyester modified polysiloxanes. Preferably, the thermoplastic polymer composition T does not contain any further polymeric components apart from the copolymer A, the graft copolymer B and optionally homopolymers of the at least one vinyl monomer A1 , the at least one vinyl cyanide monomer A2 and / or further monomers A3, or copolymers of either one of A1 or A2 with further monomers A3.

[0065] More preferably, the thermoplastic polymer composition T does not contain any further polymeric components apart from the copolymer A and the graft copolymer B.

[0066] Further additives D2 other than colorants and flame retardants may be any additives suitable for use in thermoplastic polymer compositions that are not considered colorants and flame retardants. Suitable further additives D2 include, among others, synergists for flame retardants, light stabilizers, UV absorbers, antioxidants, stabilizers for improving thermal stability, stabilizers for enhancing hydrolysis resistance and chemical resistance, anti-thermal decomposition agents, lubricants and mold release agents, fibrous and particulate fillers, reinforcing agents, nucleating agents, metal scavengers, antistatic agents, matting agents and plasticizers. 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. The amount of these UV absorbers, if present, is preferably from 0.05 to 0.45% by weight, more preferably from 0.06 to 0.4% by weight, more preferably from 0.08 to 0.25% by weight, based on the total weight of the thermoplastic polymer composition T.

[0067] 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 (Uvinul® 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). 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 0.05% to 0.45% by weight, more preferably from 0.06 to 0.4% by weight, more preferably from 0.08 to 0.25% by weight, based on the total weight of the thermoplastic polymer composition T.

[0068] 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. More preferably, 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-bu- tylphenyl)pentaerythritol diphosphite and octa-decyl-3-[3,5-di-tert-butyl-4-hydroxy- phenyl]propionate. The amount of antioxidants, if present, is preferably from 0.01 to 0.5% by weight, more preferably from 0.02 to 0.2% by weight, more preferably from 0.03 to 0.17% by weight, more preferably from 0.05 to 0.15% by weight, based on the total weight of the thermoplastic polymer composition T.

[0069] 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.

[0070] Examples of suitable matting agents include not only inorganic substances such as talc, glass beads or metal carbonates (for example MgCO3, CaCO3) 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.

[0071] 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.

[0072] Examples of lubricants and demolding agents include stearic acids, stearyl alcohol, stearic esters, polyolefin waxes and / or generally higher fatty acids, derivatives thereof and corresponding fatty acid mixtures comprising 1 to 45 carbon atoms, amide compounds having the formula R1-CONH-R2, wherein R1and R2are each independently selected from aliphatic, saturated or unsaturated hydrocarbon groups having 1 to 30 carbon atoms and fatty acid ester compounds having the formula R3-CO-OR4, wherein R3and R4are each independently selected from aliphatic, saturated or unsaturated hydrocarbon groups having 1 to 45 carbon atoms.

[0073] Furthermore, the thermoplastic composition T preferably does not contain contaminants D3 such as organic residues, dirt, metals, paper and moisture. If present, these are preferably removed by manual and / or automated sorting prior to step a).

[0074] Preferably, the thermoplastic composition T comprises 10 to 89.99% by weight, preferably 20 to 84.99% by weight, more preferably 30 to 79.9% by weight, more preferably 50 to 74.8% by weight, based on the total weight of the thermoplastic composition T, of the at least one copolymer A, 10 to 89.99% by weight, preferably 15 to 79.99% by weight, more preferably 20 to 69.9% by weight, more preferably 25 to 49.8% by weight, based on the total weight of the thermoplastic composition T, of the at least one graft copolymer B, 0.01 to 60% by weight, preferably 0.01 to 30% by weight, more preferably 0.1 to 20% by weight, more preferably 0.2 to 10% by weight, based on the total weight of the thermoplastic composition T, of the at least one additive C, and 0 to 60% by weight, preferably 0 to 40% by weight, more preferably 0 to 20% by weight, more preferably 0 to 10% by weight, based on the total weight of the thermoplastic composition T, of further components D.

[0075] When the additive C contains or consists of colorants, their amount is preferably 0.01 to 20% by weight, more preferably 0.1 to 15% by weight, more preferably 0.2 to 10% by weight, more preferably 0.5 to 8% by weight, based on the total weight of the thermoplastic composition T.

[0076] The solvent component S used in the method of the present invention may be any solvent or solvent mixture capable of at least partially dissolving the thermoplastic polymer composition T, preferably of at least partially dissolving the at least one copolymer A of the thermoplastic polymer composition T.

[0077] Preferably, the solvent component S is selected via Hansen Solubility Parameters (HSP) of the solvent component S, and the HSP of the at least one copolymer A and / or the at least one graft copolymer B.

[0078] 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).

[0079] The HSP distance (Ra) between two molecules is defined by the formula

[0080] Ra2= 4(5DI-5D2)2+ (6PI-6P2)2+ (6HI-6H2)2, 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 S), and 5D2, 6P2 and <5H2 are the respective parameters of the other molecule (e.g. the at least one copolymer A or the at least one graft copolymer B). 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).

[0081] 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).

[0082] 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.

[0083] Preferably, the solvents for determination of the HSP values for the at least one copolymer A and the at least one graft copolymer B are selected from the solvent database provided in the software HSPiP.

[0084] Preferably, at least 50 different solvents or solvent mixtures are used for the determination of the HSP values for the at least one copolymer A and the at least one graft copolymer B

[0085] 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.

[0086] Preferably, the HSP distance (Ra) between the solvent component S and the at least one copolymer A is equal to or smaller than 13 jMPa, preferably from 5 to 13 jMPa, more preferably from 7 to 13 jMPa, more preferably from 10 to 13 MPa.

[0087] Preferably, the solvent component S is 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. More preferably, the solvent component S is selected from the group consisting of ethers, esters, ketones, carbonate, hydrocarbons, alcohols, aldehydes, nitriles, amides, aromatic substances, sulfoxides, lactones and mixtures thereof. More preferably, the solvent component S is selected from the group consisting of ethers, esters, ketones, hydrocarbons, and mixtures thereof.

[0088] Even more preferably, the solvent component S is selected from the group consisting of alkyl acetates, acetone, 2-butanone, methyl ethyl ketone, methyl isobutyl ketone, tert.- butyl methyl ketone, hydrocarbons, THF and mixtures thereof. Even more preferably, the solvent component S is selected from the group consisting of alkyl acetates, methyl ethyl ketone, methyl isobutyl ketone, tert.-butyl methyl ketone, THF and mixtures thereof.

[0089] Furthermore, preferably, the solvent component S is a mixture of at least two solvents.

[0090] The Hansen Solubility Parameters of the copolymer A depend on the particular monomer composition. The solvent component S can be selected differently for different copolymers A, e.g. based on the preferred HSP distances (Ra) disclosed above.

[0091] The Hansen Solubility Parameters of an exemplary copolymer A may be as follows: 5D may be, e.g. in the range of from 18 to 25, such as from 19 to 23, or from 20 to 22. bp may be, e.g. in the range of from 5 to 11 , such as from 6 to 10, or from 7 to 8. bn may be, e.g. from 2 to 11 , such as from 6 to 10, or from 8.5 to 9.5.

[0092] The Hansen Solubility Parameters of an exemplary graft copolymer B may be as follows: o may be, e.g. in the range of from 15 to 24, such as from 17 to 23, or from 20 to 22. p may be, e.g. in the range of from 2 to 10, such as from 3 to 7, or from 5 to 6. bn may be, e.g. from 4 to 10, such as from 5 to 9, or from 6 to 8.

[0093] In step a) of the process of the invention, the thermoplastic polymer composition T is mixed with the at least one solvent component S by any suitable means known in the art. For example, mixing can by carried out by immersing the thermoplastic polymer composition T, such as post-consumer waste or post-industrial waste, in the solvent component S, and agitation or passive diffusion, preferably by stirring or shaking, more preferably by stirring.

[0094] Preferably, the thermoplastic polymer composition T and the solvent component S are mixed in a weight ratio of from 1 :99 to 25:75, preferably from 2:98 to 15:85, more preferably from 5:95 to 12:88, and preferably at a temperature of from 0 °C to the boiling point of the solvent component S, 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 S. 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 8 to 25 hours, more preferably 16 to 20 hours.

[0095] Prior to mixing step a), the thermoplastic polymer composition T may be subjected to pre-treatment steps such as manual sorting to remove visible contaminations, washing, comminution and / or automatic sorting in suitable systems. Such steps may be carried out repeatedly and in any combination or sequence.

[0096] By mixing the thermoplastic polymer composition T and the solvent component S, a mixture T1 is obtained. In addition, depending on the constituents of the thermoplastic polymer composition T and the solvent component S, a swollen and / or insoluble fraction T2 may optionally be obtained. For example, if the thermoplastic polymer composition T comprises insoluble components such as insoluble additives C2 (e.g. pigments or antimony (III) oxide), insoluble further polymers D1-2, insoluble further additives D2-2 and insoluble contaminants D3-2, an insoluble fraction will be obtained. Moreover, depending on the solvent used and the composition, amount and cross-linking degree of the graft copolymer B, a swollen fraction may be obtained. The total of insoluble and the swollen fraction form together T2. The mixture T 1 will typically contain the at least one copolymer A, soluble additives C1 (e.g. dyes and certain flame retardants), and optionally soluble further polymers D1-1 , soluble further additives D2-1 and soluble contaminants D3-1. Moreover, the at least one graft copolymer B may be contained in the mixture T1 , depending on the solvent used and the composition, amount and cross-linking degree of the graft copolymer B.

[0097] It has been surprisingly found that the presence of a swollen fraction T2 containing the at least one graft copolymer B is particularly beneficial for the separation of certain additives C, for example certain colorants and flame retardants. In particular, it has been found that certain additives C remain at least partially sorbed to the graft copolymer B, and can therefore be effectively separated from the mixture T 1 together with the swollen graft copolymer B. The separation of insoluble additives C2, for example insoluble colorants such as carbon black was found to be particularly effective when a swollen fraction containing the at least one graft copolymer B is obtained in step a).

[0098] Typically, at least 50% by weight, for example at least 80% by weight, often at least 90% by weight, in particular at least 95% by weight of the insoluble additives C2, for example insoluble colorants such as carbon black, and optional insoluble further components D- 2, e.g. flame retardant synergists such as antimony(lll)oxide, based on the total weight of insoluble components C2 and D-2 originally present in the thermoplastic polymer composition T, remain sorbed to the graft copolymer B in the swollen and / or insoluble fraction T2, and thus can be effectively separated from the mixture T 1 . Therefore, it is preferable to select at least one solvent component S in which the graft copolymer B swells.

[0099] Preferably, the solvent component S is selected via the Hansen Solubility Parameters as described above, thus that the HSP distance Rabetween the at least one solvent component S and the at least one graft copolymer B is smaller than 12 MPa, preferably from 4 to 12 jMPa, more preferably from 5 to 12 jMPa, more preferably from 6 to 11.5jMPa, more preferably from 8.5 to 11.5 jMPa. Preferably, the distance Rabetween the solvent component S and the at least one copolymer A (which were described above) is greater than the distance Rabetween the solvent component S and the at least one graft copolymer B.

[0100] The term “sorption” refers to any type of interaction between a solid component, referred to as “sorbent” and a further compound, wherein the interaction leads to the further compound becoming attached (also referred to as “sorbed”) to the sorbent. Preferably, the term “sorption” refers to adsorption, absorption or a combination thereof. Accordingly, the term “sorbent” preferably means adsorbent, absorbent or a combination thereof, and the term “sorbed” preferably means adsorbed, absorbed or a combination thereof. Typical sorbents are partly or fully insoluble in the solvent component S, and feature a high surface area in relation to their weight. Examples are grafted rubber, pulverized inorganic substances, such as aluminium oxide, mica or silica, and activated carbon.

[0101] Where a swollen and / or insoluble fraction T2 is obtained, it is at least partially separated from the mixture T1. Such separation may be carried out by any means known in the art for separation of solutions from insoluble components.

[0102] Preferably, the swollen and / or insoluble fraction T2 is separated from the mixture T1 by gravimetric separation, filtration or a combination thereof. More preferably, the swollen and / or insoluble fraction T2 is separated from the mixture T1 by gravimetric separation.

[0103] 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. 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. The mixture T1 obtained in step a) is further subjected to a step c) of at least partially separating soluble additives C1 and optionally further soluble components D-1 from the at least one copolymer A in mixture T1. For example, the at least partial separation of soluble additives C1 and optionally further soluble components D-1 may be carried out by precipitation of the at least one copolymer A from the mixture T1. lt has been surprisingly found that the at least partial removal of soluble additives C1 , is particularly effective if the mixture T1 is subjected to at least one step of sorption, using at least one sorbent.

[0104] Preferably, the at least partial separation of soluble additives C1 in step c) is carried out by subjecting the mixture T1 to at least one step of sorption, using at least one sorbent. The at least one sorbent is preferably selected from activated carbon, aluminum oxide, calcium carbonate, silicon dioxide and combinations thereof, which have been found capable of at least partially removing soluble additives C1 from the mixture T 1 without substantially removing the at least one copolymer A therefrom. More preferably, the sorbent comprises activated carbon. More preferably, the sorbent comprises activated carbon and at least one inorganic component.

[0105] More preferably, the inorganic component is aluminum oxide. Where at least two sorbents are used, such as activated carbon 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 sorbents in each step, or may be carried out in a single step, using a mixture of the sorbents. Where sorption is carried out in at least two steps, using activated carbon and at least one inorganic component such as aluminum oxide, the step using activated carbon is preferably carried out first.

[0106] Where a mixture of sorbents is used, the sorbents are preferably layered on top of each other. In this case, if the mixture contains activated carbon, the activated carbon is preferably layered on top of the other sorbents, preferably on top of aluminum oxide.

[0107] Typically, at least 50% by weight, for example at least 80% by weight, often at least 90% by weight, in particular at least 95% by weight, particularly at least 99% by weight of the soluble additives C1 , of the soluble further additives D2-1 and of the soluble contaminants D3-1 , preferably soluble colorants, based on the total weight of soluble additives C1 , soluble further additives D2-1 and soluble further contaminants D3-1 originally present in the thermoplastic polymer composition T, become sorbed to the sorbents in step c), and thus can be effectively separated from the mixture T 1 .

[0108] The at least one step of sorption is preferably combined with at least one further separation step, such as filtration and / or gravimetric separation, as described above for step b). Preferably, the at least one step of sorption is combined with filtration. For example, step c) may comprise mixing the mixture T1 with the at least one sorbent by stirring or shaking, and filtering the resultant slurry using a filter and / or frit, or by centrifugation of the resultant slurry. In cases where step c) comprises two or more steps of sorption, the further separation step is preferably carried out after each step of sorption.

[0109] Where step c) comprises mixing the mixture T 1 with the at least one sorbent, such mixing may be carried out before, after or simultaneously with step b) of at least partially separating the swollen and / or insoluble fraction T2, if present, from the mixture T1. For example, the sorbent may be added to the thermoplastic polymer composition T before or after mixing with the at least one solvent component S to obtain a mixture T 1 and a swollen and / or insoluble fraction T2 comprising the sorbent, and any of the soluble components sorbed to the sorbent.

[0110] Step c) may also comprise placing the at least one sorbent into a filter and / or frit and filtering the mixture T1 through the at least one sorbent. In cases where two or more sorbents, preferably activated carbon and an inorganic component, more preferably activated carbon and aluminum oxide, are used, the different sorbents are preferably layered on top of each other in the filter and / or frit. More preferably, activated carbon is layered on top of an inorganic component, more preferably on top of aluminum oxide. For example, step c) may comprise filtering the mixture T1 using a column packed with the at least one sorbent. Optionally, after filtration of the mixture T 1 using a column packed with the at least one sorbent, one or more additional filtration steps may be carried out, to remove residual amounts of fine disperse particles, such as sorbent particles that passed the filter or frit. In such case, preferably at least one filtration through a filter having a pore size in the range of from 0.1 to 1 pm, more preferably in the range of from 0.15 to 0.5 pm, more preferably from 0.2 to 0.45 pm is carried out. More preferably, at least one filtration through a filter having a pore size in the range of from 0.3 to 1 pm, preferably from 0.35 to 0.5 pm, more preferably from 0.4 to 0.45 pm and at least one filtration through a filter having a pore size in the range of from 0.1 to 0.25 pm, preferably from 0.15 to 0.25 pm are carried out to remove residual amounts of fine disperse particles.

[0111] After at least partial separation of soluble additives C1 from the at least one copolymer A in mixture T1 , a polymer composition T3 is isolated from the mixture T1 in step d), preferably by removing the solvent from the mixture T 1 obtained in step c). The isolation may be carried out by any suitable means known in the art, e.g. by precipitation of the dissolved polymeric components of mixture T 1 using a precipitating agent, evaporation, cooling or a combination thereof, and optionally further separation techniques such as extrusion, filtration, centrifugation, decanting, and using a cannula. For example, the dissolved polymeric components may be precipitated from the mixture T1 by adding a precipitating agent, such as a solvent in which the polymeric components, preferably the at least one copolymer A are insoluble (also referred to as “anti-solvent”).

[0112] For example, such anti-solvent may be selected from solvents that have an HSP distance (Ra) from the at least one copolymer A of greater than 13, preferably from 14 to 21. More preferably, the anti-solvent is selected from alcohols and unsaturated hydrocarbons, more preferably from methanol, ethanol, hexane, heptane and cyclohexane, more preferably from methanol, hexane and heptane. When an anti-solvent is used, the ratio of the solvent component S and the anti-solvent is preferably in the range of from 1 :1 to 1 :10, more preferably from 1 :2 to 1 :10, more preferably from 1 :3 to 1 :5.

[0113] The polymeric components precipitated from the mixture T 1 , preferably the at least one copolymer A, may further be optionally washed with the anti-solvent or a mixture thereof with a solvent component S as described above. Washing may be carried out once or repeatedly. When washing involves the use of a solvent component S, it is preferably carried out at a temperature below the boiling point of the washing liquid, preferably around ambient temperature, more preferably at or below 25 °C, even more preferably between -30 and 25 °C. Preferably, precipitation using an anti-solvent is followed by at least one step of washing using an anti-solvent. Preferably, the amount of anti-solvent used in the washing step is from 0.1 to 3, more preferably from 0.2 to 2, more preferably from 0.25 to 1 times the amount thereof used for precipitation.

[0114] The dissolved polymeric components, preferably the at least one copolymer A, may also be precipitated from the mixture T1 by evaporation of the solvent component S. Evaporation may involve heating the mixture T1 , e.g. to the boiling point, and / or subjecting the mixture T1 to reduced pressure, thereby increasing the concentration of the dissolved polymeric components, preferably the at least one copolymer A, in the mixture T 1 . Evaporation to dryness may also be carried out.

[0115] The dissolved polymeric components, preferably the at least one copolymer A, may also be precipitated from the mixture T1 by cooling the mixture T1 to a temperature, at which the solubility of the polymeric components in the at least one solvent component S is low. For example, the mixture T 1 may be cooled to a temperature between the freezing point of the solvent component S and 15 °C, preferably to a temperature between -78 °C and 0 °C, more preferably to a temperature between -30 °C and -10 °C.

[0116] The dissolved polymeric components, preferably the at least one copolymer A may also be precipitated by application of steam and / or supercritical, gaseous or solid carbon dioxide to the mixture T 1. Such precipitation methods are described, e.g. in “Mean Aspects Controlling Supercritical CO2 Precipitation Processes” (Antonio Montes et al., in Heat and Mass Transfer- Advances in Science and Technology Applications, 2019), “Supercritical CO2 antisolvent precipitation of polymer networks of L-PLA, PMMA and PMMA / PCL blends for biomedical applications" (Arlete Vega-Gonzalez et al., Eur. Polymer J. 2008, 44(4), pp. 1081-1094), and in US 5,266,211.

[0117] The polymeric components, preferably the at least one copolymer A, precipitated from the mixture T1 are preferably separated from the supernatant, e.g. by gravimetric separation as described above, or by filtration as described above, preferably by filtration or by centrifugation as described above. If gravimetric separation is used, the supernatant is preferably removed by means of cannula, pipette or decantation. Preferably, industrial scale separation techniques are used, like larger scale decanter, centrifuges, extrusion combined optionally with mechanical squeezing.

[0118] Preferably, the isolation of the polymer composition T3 in step d) comprises precipitation of the at least one copolymer A from mixture T1 by a combination of evaporation of the solvent and cooling, followed by removal of the supernatant as described above. Preferably, precipitation is not carried out using a precipitation agent such as an anti-solvent. More preferably, no precipitation agents such as anti-solvents are used in the entire method.

[0119] The polymeric components precipitated from the mixture T 1 , preferably the at least one copolymer A, by any of the above methods may further be optionally washed with the anti-solvent, the solvent component S as described above, or a mixture thereof.

[0120] Washing may e.g. be carried out once or repeatedly. When washing involves the use of a solvent component S, it is preferably carried out at a temperature below 25 °C, preferably between the freezing point of the solvent component S and 15 °C, preferably at a temperature between -78 °C and 0 °C, more preferably to a temperature between -30 °C and -10 °C. Preferably, precipitation using an anti-solvent is followed by at least one step of washing using an anti-solvent.

[0121] The precipitated polymeric components are obtained as a polymer composition T3, which will typically comprise the at least one copolymer A, and not more than 50% by weight, often not more than 20% by weight, in particular not more than 10% by weight of the at least one additive C, preferably of colorants, and of the optional further components D originally present in the thermoplastic composition T, based on the total weight of the components C and D originally present in the thermoplastic composition T.

[0122] The swollen and / or insoluble fraction T2 obtained in step b) after separation from the mixture T1 may also be further processed. For example, it may optionally be subjected to an extraction step, in particular a solvent extraction step in an additional step b1), e.g. in order to recover components of the swollen and / or insoluble fraction T2 for further use. For example, the at least one solvent component S may be used, in order to recover more of the components of mixture T1 , which may be combined with that obtained in step a) and processed together therewith.

[0123] Alternatively, a different solvent or solvent mixture may be used, in order to extract one or more components from the swollen and / or insoluble fraction T2 that are different from the components of the mixture T 1 . Such extraction may be carried out once or repeatedly, with the same or different solvents or solvent mixtures, in order to extract the same or different components of the swollen and / or insoluble fraction T2, or to purify the fraction T2. The dissolved components may be separated from the insoluble components in each extraction step e.g. as described above for step b). Typically, insoluble additives C2, for example insoluble colorants such as carbon black, and certain other components of the thermoplastic polymer composition T remain sorbed to the at least one graft copolymer B in the swollen and / or insoluble fraction T2, even after extraction is carried out in step b1).

[0124] The swollen and / or insoluble fraction T2 can then be used as a source for a raw material based on the at least one graft copolymer B. Preferably, a polymer composition T4, preferably a colored polymer composition T4, is isolated from the swollen and / or insoluble fraction T2 in step e). Typically, the polymer composition T4 will contain at least 50% by weight, for example at least 80% by weight, often at least 90%, by weight of the insoluble additives C2, based on the total amount of insoluble additives C2 present in the thermoplastic polymer composition T.

[0125] Furthermore, the polymer composition T4 will typically contain not more than 50% by weight, for example not more than 20% by weight, often not more than 10% by weight of soluble additives C1 , based on the total amount of soluble additives C1 originally present in the thermoplastic polymer composition T.

[0126] The polymer composition T3, which will typically contain a major portion of the at least one copolymer A, may be further processed and / or used in any way known in the art for copolymers of aromatic vinyl monomers A1 and vinyl cyanide monomers A2. Similarly, the polymer composition T4, which will typically contain a major portion of the at least one graft copolymer B, may be further processed and / or used in any way known in the art for graft copolymers comprising a rubbery core and a polymeric shell comprising repeating units of at least one aromatic vinyl monomer A1 and / or repeating units of at least one vinyl cyanide monomer A2. For example, the polymer composition T3 and / or the polymer composition T4 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. The polymer composition T3 and the polymer composition T4 may be used individually or together, optionally with as a mixture with virgin materials, such as virgin polymers (preferably virgin graft copolymers and / or virgin copolymers of monomers A1 and A2), colorants and other additives.

[0127] For example, the polymer composition T3, the polymer composition T4, a mixture thereof, or a mixture of T3 or T4 with at least one virgin material may be used as a thermoplastic polymer composition according to the invention, which may be used for the preparation of a molded article.

[0128] The present invention is further illustrated by the following examples, Figures and claims.

[0129] EXAMPLES

[0130] ABS-based thermoplastic composition samples of commercially available nature-colored, yellow, brown, blue and black ABS samples.

[0131] Furthermore, colored ABS obtained from a plant for mechanical recycling was used.

[0132] The ABS used in the experimental part is made of 30% by weight of graft rubber and 70% by weight of styrene acrylonitrile (SAN) polymer, including additives such as lubricants, colorants, stabilizers.

[0133] The styrene-acrylonitrile (SAN) polymer matrixes in all samples is composed of 75% by weight of styrene and 25% by weight of acrylonitrile. The dispersed acrylonitrile-butadi- ene-styrene (ABS) graft copolymer rubber particles are consisting of 60% by weight of a rubber phase and 40% by weight of SAN graft shell. The rubber phase is crosslinked and consists mainly of polymerized butadiene.

[0134] For determination of the Hansen Solubility Parameters, a corresponding virgin SAN copolymer and a corresponding virgin ABS graft copolymer rubber were used.

[0135] The virgin SAN copolymer and the virgin ABS graft rubber were characterized separately concerning their Hansen Solubility Parameters based on the HSP sphere method, reference is made to “Hansen Solubility Parameters: A User’s Handbook” (C. M. Hansen, 2007, CEC Press, 2. ed.). Therefore, the SAN copolymer and the ABS graft rubber were mixed with a range of 58 different solvents with known HSP values from the database found in the Software “Hansen Solubility Parameters in Practice” (HSPiP, version 5.4.04, published by Hansen-Solubility.com, developed by Dr. Hansen's group) over a period of 24 h (10 g / L) and evaluated by the HSP sphere method. As solubility criteria for SAN the complete solubility was selected. For the ABS graft rubber the applied criteria was an almost complete dissolution, with few gel-like particles remaining, as the ABS rubber was not totally soluble due to the crosslinking in the butadiene core. For each of SAN and ABS rubber, a sphere in the HSP space was calculated by applying the genetic fitting algorithm of the Software Hansen Solubility Parameters in Practice (HSPiP, version 5.4.04, published by Hansen-Solubility.com, developed by Dr. Hansen's group). The HSP values of the point in the HSP space corresponding to the center of the respective sphere were determined as the Hansen Solubility Parameters of the SAN or ABS rubber.

[0136] The HSP parameters of SAN polymer and ABS rubber are shown in Table 1

[0137] Table 1 :

[0138] Example 1 :

[0139] 200 mg of virgin SAN or 100 mg of virgin ABS rubber were mixed with 20 mL of solvents selected from pentane, acetone, acetonitrile (ACN), methanol (MeOH), methyl isobutyl ketone (MIBK), methyl ethyl ketone (2-butanone), toluene, tetrahydrofuran (THF), ethyl acetate (EE), cyclohexanone, anisole, acetophenone, 1 ,4-dioxane, acetic acid, dimethyl sulfoxide (DMSO), 1 ,2-dichlorobenzene, dichloromethane (CH2CI2), or chloroform.

[0140] Afterwards the samples were vigorously stirred for 24 h at 22°C. The evaluation of the samples was performed visually after a settling time of 144 h.

[0141] The dissolution and floating behavior of the virgin SAN and the HSP distance Rathereof from the respective solvents and the dissolution, swelling and floating behavior of the virgin ABS rubber and the HSP distance Rathereof from the respective solvents is disclosed in Table 2.

[0142] For evaluation of dissolution behavior, following criteria were evaluated:

[0143] Dissolution (D): + means dissolved; - means not dissolved;

[0144] Swelling (S): + means high degree of swelling; 0 means medium degree of swelling; - means low degree of swelling or no swelling;

[0145] Flotation (F; only if not dissolved): + means floating; - means depositing. Table 2:

[0146] From the dissolution evaluation it was found that SAN is soluble in a solvent if the HSP distance Rais equal to or smaller than 13, and that a medium or high degree of swelling of ABS rubber in a solvent is observed if the distance HSP distance Rais equal to or smaller than 12.

[0147] Example 2:

[0148] In a series of tests, 0.2 g of brown, blue and black ABS samples were mixed with 5 mL of a solvent (selected from acetone, anisole, ethyl acetate, y-butyrolactone, 2-butanone, THF, toluene, MIBK, CHCh and cyclohexanone) on a rolling table for 3 d and afterwards stirred for 20 min. The samples with non-precipitating rubber were evaluated after settling at standard gravity for 7 d. The samples with precipitating rubber were evaluated after centrifugation at 6500 G for 10min. The appearance of the mixtures was evaluated visually. In most solvents, a clear separation of the colored swollen rubber fraction from the solution was visible. Based on the remaining color in the solution, the samples were ranked based on their position in the test from 1 (best in test) to 10 (worst in test).

[0149] The HSP parameters of the solvent, the distance Rabetween the solvent and the SAN (A) and the ABS rubber (B), the positions in the test with each of the colored black, blue and brown ABS as well as the overall sum of the positions for all three colours are disclosed for the respective solvents in Table 3

[0150] Table 3 Good results were observed for acetone, 2-butanone, toluene, ethyl acetate and methyl isobutyl ketone, with overall best performance for ethyl acetate and methyl isobutyl ketone. In these solvents, a clear separation of the swollen rubber fraction with sorbed colorant was observed, and the supernatant was clear and colorless. This shows the efficiency of the removal of insoluble colorants, like the usually hard to remove carbon black in the black sample.

[0151] FIG. 1 shows photographs of the samples after the settling of the rubber at standard gravity, where the top row shows the mixtures with blue ABS, the middle row shows the mixtures with brown ABS and the bottom row shows the mixtures with black ABS, and where the solvents used (from left to right) were acetone, anisole, ethyl acetate, / -butyrolactone, 2-butanone, tetrahydrofuran, toluene, methyl isobutyl ketone, chloroform and cyclohexanone.

[0152] FIG. 2 shows photographs of a selection of samples after centrifugation (or settling at standard gravity for / -butyrolactone where applicable), for the five samples of each colour, where best separation performance was observed. The top row shows the mixtures with blue ABS (from left to right with ethyl acetate, methyl isobutyl ketone, acetone, 2- butanone and / -butyrolactone), the middle row shows the mixtures with brown ABS (from left to right with ethyl acetate, methyl isobutyl ketone, toluene, 2-butanone and tetrahydrofuran) and the bottom row shows the mixtures with black ABS (from left to right with ethyl acetate, methyl isobutyl ketone, toluene, acetone and / -butyrolactone. In contrast, in a comparable test with yellow ABS samples in ethyl acetate and methyl isobutyl ketone, the corresponding highly soluble colorant essentially was dissolved, and was almost not sorbed to the swollen rubber fraction, regardless of the solvent used. It can be removed by precipitation and washing (e.g. as shown in Example 4) or by filtration with filter media (e.g. as shown in Example 8-11).

[0153] Example 3:

[0154] 4 g of a mixed colored ABS composition (yellow, blue, brown and black in equal amounts) was stirred with 36 g of MIBK for 16 h at room temperature. The resultant slurry was subjected to filtration using a folded paper filter. After 3 days, a clear yellow filtrate and 1 .69 g of a dark colored solid residue were obtained. The filtrate was dried in a vacuum drying oven at 50 °C for 3 days, resulting in 2.57 g of yellow colored SAN copolymer.

[0155] FIG. 3 shows photographs of the slurry placed into the paper filter (left) and the obtained yellow filtrate and dark colored solid residue remaining in the paper filter (right) after separation.

[0156] Similar results were obtained when filtration was replaced by centrifugation. These results show that the insoluble blue, brown and black colorants essentially are sorbed to the swollen and / or insoluble ABS rubber fraction and thus can be effectively separated from the SAN fraction, whereas the soluble yellow colorant remains in solution.

[0157] In a similar experiment 100 g of a mixed colored ABS composition (yellow, blue, brown and black in equal amounts) was mixed with 900 g of MIBK for 2 h at 110°C, resulting in a significantly increased dissolution rate but also led to a stronger coloration by insoluble colorants of the solution after removal of the strongly colored swollen and / or insoluble ABS rubber fraction.

[0158] This result shows, that higher dissolution temperatures can interfere with the sorption of the colorants by the rubber. This effect may be utilized after separation of the dissolved fraction from the insoluble and / or swollen fraction, to partially remove sorbed additives or colorants from the rubber.

[0159] Ultrasonic treatment can also interfere with the sorption of colorants by the rubber, and can be utilized alone or in combination with higher dissolution temperatures after separation of the dissolved fraction from the insoluble and / or soluble fraction, to partially remove sorbed additives or colorants from the rubber.

[0160] FIG. 4 shows photographs of mixtures of ABS rubbers (from left to right: black, blue and brown) after separation of the dissolved fraction, and after subjecting the colored insoluble residue to ultrasonic treatment in chloroform for 15 min.

[0161] Example 4

[0162] 3.33 g of yellow ABS composition was dissolved in 30 g of ethyl acetate or MIBK and subjected to centrifugation (40 min, 6500 G). The yellow colored SAN solutions in ethyl acetate and MIBK, respectively, were decanted, leaving behind a slightly yellow ABS rubber residue in both cases.

[0163] 5 g of each solution were subjected to precipitation in 25 g of an anti-solvent selected from methanol and n-hexane, followed by centrifugation (40 min, 6500 G) and decantation. The resultant SAN precipitates had a similar, slightly yellow appearance in all four cases (EE + MeOH, EE + n-hexane, MIBK + MeOH, MIBK + n-hexane). The decanted solvent was in all cases of a saturated yellow colour.

[0164] Washing of the precipitates with the same amount of the respective anti-solvent, led to further removal of the yellow colorant, resulting in an off-white SAN precipitate in all four cases.

[0165] Precipitation from clear yellow SAN solutions in MIBK was repeated with different volume ratios of MIBK: MeOH and MIBK: hexane from 1 :1 to 1 :10. Precipitation was observed in all cases, and the solid SAN precipitate could be separated from the supernatant by filtration of centrifugation. Best dispersion appearance of the mixtures was observed for ratios from 1 :5 to 1 :10 using MeOH and ratios from 1 :3 to 1 :10 using hexane. Precipitation using heptane as antisolvent proceeded similarly as with hexane. With cyclohexane as antisolvent, finer particles were obtained.

[0166] FIG. 5 shows photographs of the decanted yellow SAN solutions and slightly yellow ABS rubber centrifugation residues separated from each other in ethyl acetate (left) and MIBK (right).

[0167] FIG. 6 shows photographs of the slightly yellow SAN precipitates from ethyl acetate (left) precipitated with MeOH or hexane, and from MIBK (right) precipitated with MeOH or hexane.

[0168] FIG. 7 shows photographs of the dried slightly yellow SAN precipitates from ethyl acetate using hexane (top left) or methanol (top right) as antisolvent and from MIBK using hexane (bottom left) and methanol (bottom right) as antisolvent before and after washing with the same antisolvent (left and right sample, respectively).

[0169] FIG. 8 shows photographs of the mixtures after precipitation of SAN from MIBK using MeOH (left) or hexane (right) at ratios 1 :1 , 1 :2, 1 :3, 1 :4, 1 :5 and 1 :10.

[0170] FIG. 9 shows photographs of the mixtures after precipitation of SAN from MIBK using cyclohexane, hexane and heptane at ratios 1 :3 and 1 :4.

[0171] Examples 5 and 6

[0172] 20 g of an artificial 1 : 1 : 1 : 1 mixture of yellow ABS, blue ABS, brown ABS and black ABS and 180 g ethyl acetate (Example 5) were stirred at 23 °C for 16 h at 250 rpm using a KPG stirrer, after which centrifugation for 20 min at 6500 G was performed 4 times. The SAN solution was separated by decantation, and the undissolved colored ABS rubber residue was dried at 50 °C for 6 d under vacuum, to yield 8.22 g of dried, dark colored ABS rubber.

[0173] The SAN solution was precipitated in n-hexane at a weight ratio of 1 :4 (SAN solution : n- hexane) and filtered (clear yellow filtrate), and the precipitated SAN was washed with n- hexane (45% of n-hexane amount used for precipitation). The washed SAN was dried under vacuum at 50 °C, to yield 11 .32 g of dried, slightly yellow and greyish SAN polymer.

[0174] The Example was repeated, using 180 g of MIBK (Example 6) instead of ethyl acetate, yielding 7.99 g of dried, dark colored ABS rubber, and 11.61 g of dried, slightly yellow SAN polymer. The SAN products obtained according to Examples 5 and 6 were processed by compounding in a DSM twin-screw compounder (40 rpm, 220 °C, 2 min run time, 11 g sample weight), from which the molten product was directly filled into a heated cylinder, from which the injection molding of plates with the DSM injection molder was performed (220 °C melt, 60 °C mold, 8 bar, 15 s injection time). The sample plates showed some overflow, thus the thickness in the central 27 mm diameter part was around 1.4 mm, and in the outer overflow part around 0.4 mm. The sample plate from Example 5 had a greenish coloration due to the presence of traces of carbon black alongside some yellow colorant precipitated with the SAN polymer; the sample plate from Example 6 had a yellow coloration due to some yellow colorant precipitated with the SAN polymer.

[0175] FIG. 10 shows photographs of the mixture of colored ABS in the respective solvent after centrifugation for Example 5 (left) and Example 6 (right).

[0176] FIG. 11 shows photographs of the dried, dark colored ABS rubber (top) and the decanted SAN solution (bottom) obtained in Example 5 (left) and Example 6 (right).

[0177] FIG. 12 shows photographs of the precipitating mixture with hexane (left), the filtration products obtained therefrom (center) and a bag of isolated SAN polymer (right) obtained in Example 5 (top) and Example 6 (bottom).

[0178] FIG. 13 shows photographs of the dry SAN polymers (in bags) and the respective injection molded plates obtained from the SAN polymers of Example 5 (left) and Example 6 (right).

[0179] Example 7

[0180] 40 g of an artificial 1 : 1 : 1 : 1 mixture of yellow ABS, blue ABS, brown ABS and black ABS and 160 g MIBK were stirred at 23 °C for 72 h at 250 rpm using a KPG stirrer, after which centrifugation for 200 min at 6500 G and for 20 min at 14000 G was performed. The SAN solution was separated by decantation, and worked up according to Example 6.

[0181] The dried SAN polymer had a stronger yellow coloration than that obtained in Example 6 due to higher concentration of the colored ABS starting materials. Dilution of the SAN solution with more MIBK prior to precipitation enables further reduction of the yellow coloration in the resultant dried SAN polymer.

[0182] FIG. 14 shows photographs of the mixture of colored ABS in MIBK after centrifugation (left) and the dried SAN polymer (right) obtained in Example 7. Examples 8, 9 and 10

[0183] Following thermoplastic polymer composition samples were used:

[0184] 100 g of an artificial 1 : 1 : 1 : 1 mixture of yellow ABS, blue ABS, brown ABS and black ABS (Example 8);

[0185] 100 g of a colored ABS sample from a plant for mechanical recycling (Example 9);

[0186] 129.67 g of a gray-colored ABS sample from a plant for mechanical recycling (Example 10).

[0187] The ABS samples were mixed in a ratio of 1 :9 with MIBK at room temperature for 16 h at 250 rpm using a KPG stirrer, after which centrifugation for 20 min at 14000 G was carried out and the SAN solution was decanted from the insoluble fraction containing ABS rubber.

[0188] The insoluble fraction was subjected to a further centrifugation at 6500 G for 10 min, to increase the amount of SAN solution, which was again decanted from the insoluble fraction.

[0189] The SAN solution was precipitated in n-heptane at a weight ratio of 1 :4 (SAN solution : n-heptane) and filtered, and the precipitated SAN was washed with n-heptane (25% of n-heptane amount used for precipitation). The washed SAN was dried under vacuum at 50 °C.

[0190] The insoluble fraction of colored ABS rubber was precipitated in n-heptane at a weight ratio of 1 :2 (wet ABS rubber from decantation : n-heptane) and filtered, and the precipitated rubber was washed with n-heptane (75% of n-heptane amount used for precipitation). The washed rubber was dried under vacuum at 50 °C.

[0191] The amounts of isolated dried ABS rubber and dried SAN are listed in Table 4.

[0192] Table 4

[0193] The SAN products were processed by compounding in a DSM twin-screw compounder (40 rpm, 220 °C, 2 min run time, 11 g sample weight), from which the molten product was directly filled into a heated cylinder, from which the injection molding of plates having a diameter of 27 mm and 1.15 mm thickness with the DSM injection molder was performed (220 °C melt, 60 °C mold, 8 bar, 15 s injection time).

[0194] The molded transparent plate of Example 8 had a yellow color, the molded transparent plate of Example 9 had a brown color. The yellow color of Example 8 originated from the remaining deriched amount of the soluble yellow colorant. The brown color of Example 9 originated from traces of different kinds of insoluble colorants and the deriched amount of different kinds of soluble colorants, which were present in the waste sample from mechanical recycling. The molded transparent plate of Example 10 was essentially colorless.

[0195] The weight average molecular weights (Mw) of the obtained SAN copolymers (measured by gel permeation chromatography calibrated to polystyrene standards) were found to be between 163000 and 177000 g / mol, and the polydispersity indices (Mw / Mn) were found to be between 2.3 and 2.4. In comparison, the virgin SAN had an Mw of about 168.000 and an Mw / Mn of 2.5. This shows that the SAN copolymers obtained by the method of the invention from used plastics are similar to the virgin material used for the preparation of the used ABS.

[0196] The sample plates of Examples 5, 6, 8, 9 and 10 were analyzed using a JASCO V-670 spectrophotometer. The presence of yellow colorant in the yellow sample plates obtained in Examples 6 and 8 was confirmed by absorption maxima at 400-450 nm and 670 nm.

[0197] The same absorption maxima were also present for the greenish sample plate obtained in Example 5, however, the spectrum was shifted to higher absorbance values due to higher scattering that may be attributed to the presence of traces of carbon black, and two small absorption maxima were visible at 560 and 610 nm.

[0198] For the brown sample plate of Example 9, obtained from mechanically recycled colored ABS, the absorption maxima of the yellow colorant were hardly present, but the spectrum was shifted to higher absorbance values similarly to Example 5, due to higher scattering that may be attributed to the presence of traces of carbon black.

[0199] The essentially colorless sample plate of Example 10 obtained from mechanically recycled gray-colored ABS did not show any absorption maxima.

[0200] FIG. 15 shows photographs of the initial artificial colored mixture as used in Example 8 (top), the initial multicolored ABS sample from mechanical recycling as used in Example 9 (center) and the initial gray-colored ABS sample from mechanical recycling as used in Example 10 (bottom).

[0201] FIG. 16 shows photographs of the dry SAN polymers (in bags) and the respective injection molded plates obtained from the SAN polymers of Example 8 (left), Example 9 (center) and Example 10 (right).

[0202] FIG. 17 shows the absorption spectra recorded by the JASCO V-670 spectrophotometer for Examples 5, 6, 8, 9 and 10.

[0203] Example 11

[0204] A yellow SAN solution obtained by mixing yellow ABS with MIBK, centrifugation and decantation as described in Example 4 was prepared and filtered through a bed of Aluminum Oxide N (Fisher Scientific) having a height of about 3 cm, followed by extraction of the aluminum oxide with more MIBK to eluate the SAN completely.

[0205] A substantial amount of yellow colorant was sorbed to the aluminum oxide, with small amounts still being present in the filtrate.

[0206] The same procedure was carried out, however the colored mechanically recycled ABS sample used in Example 9 was used instead of yellow ABS (turbid, brown SAN solution). Sorption of yellow colorant on the aluminum oxide was observed. Small amounts of colorants were still present in the filtrate (brown turbid mixture).

[0207] FIG. 18 shows photographs of the SAN solutions before filtration through the bed of Aluminum Oxide N (left) and the results of the filtration (right) for the yellow ABS sample (top) and the colored mechanically recycled ABS sample (bottom).

[0208] Example 12

[0209] Example 11 was repeated, however a bed of activated carbon having a thickness of about 2 cm was used instead of the bed of Aluminum Oxide N. In both cases (yellow and brown SAN solutions of Examples 4 and 9, respectively) the original coloration was removed entirely, however, a small amount of activated carbon was washed out from the filter bed and was visible in the filtrate.

[0210] The brown solution of Example 9 was also filtered through a bed of silica having a thickness of about 3 cm, leading to removal of insoluble colorant particles. FIG. 19 shows photographs of the SAN solutions after filtration for the yellow ABS sample (left) through the bed of activated carbon, and for the colored mechanically recycled ABS sample (right) through the bed of activated carbon (top) or silica (bottom).

[0211] Example 13

[0212] Example 11 was repeated, however a bed of a mixture of activated carbon with Aluminum Oxide N having a total thickness of about 2 cm was used instead of the bed of Aluminum Oxide N. In both cases (yellow and brown SAN solutions of Examples 4 and 9, respectively) the original coloration was removed entirely.

[0213] FIG. 20 shows photographs of the colorless solutions eluted from the filtration (left) and the mixed bed of activated carbon and Aluminum Oxide N after filtration (right) for the yellow ABS sample (top) and the colored mechanically recycled ABS sample (bottom).

[0214] Example 14

[0215] Example 11 was repeated, however a bed of activated carbon (2 cm) layered above a bed of Aluminum Oxide N (2.7 cm) was used instead of the bed of Aluminum Oxide N alone. In both cases (yellow and brown SAN solutions of Examples 4 and 9, respectively), colorless and clear filtrates were obtained.

[0216] A colorless and clear filtrate was also obtained, when a mixture of the mechanically recycled ABS and yellow ABS was used as starting ABS composition instead of the individual compounds. The colorless and clear solutions were dried to obtain colorless SAN copolymers. Colorless and clear SAN copolymers are also obtained when any of the SAN solutions obtained in Examples 2 to 10 are subjected to filtration through activated carbon and Aluminum Oxide N.

[0217] The weight average molecular weights (Mw) and the polydispersity indices (Mw / Mn) were not affected by filtration using sorbents in any of the examples.

[0218] FIG. 21 shows a photograph of the colorless solutions eluted from the filtration of the colored mechanically recycled ABS sample, together with the layered bed of activated carbon and Aluminum Oxide N after filtration.

[0219] FIG. 22 shows a photograph of a colorless solution obtained from the filtration according to Example 14 for the colored mechanically recycled ABS sample (left flask) and for a mixture thereof with yellow ABS (right flask). FIG. 23 shows the absorbtion spectra recorded by the JASCO V-670 spectrophotometer before (grey lines) and after filtration (black lines) according to Example 14 for the colored mechanically recycled ABS sample alone (dotted lines) and for a mixture thereof with yellow ABS (solid lines), both showing hardly any absorption.

[0220] Example 15

[0221] A sample containing 76 wt.-% nature-colored ABS, 16 wt.-% Tetrabromobisphenol A (flame retarder) and 8 parts Sb2C>3 (synergist) was prepared by conventional compounding using a DSM twin screw compounder at 40 rpm and 220 °C.

[0222] 16.56 g of the sample was mixed with 149.04 g of MIBK for40h at 23 °C using a magnetic stirrer. The resultant mixture and additional 4.62g of MIBK was subjected to centrifugation at 20 °C for 20 min at 14000 G, and decantation. The insoluble fraction was subjected to a further centrifugation at 6500 G for 10 min and decantation, to increase the amount of SAN solution, which was again decanted from the insoluble fraction.

[0223] 147.26 g of SAN solution and 22.05 g of wet rubber were obtained.

[0224] The SAN solution was mixed with 588.36 g of n-heptane for precipitation, the precipitate was filtered, washed with additional 150 g n-heptane, and dried at 50 °C under vacuum, yielding 8.33 g of dry SAN. The filtrate was evaporated to dryness, yielding 2.35 g of solid residue.

[0225] Elemental analysis showed that the bromine content, originating from the Tetrabromobisphenol A in the SAN copolymer was reduced by 85 mass-%, and the antimony content was reduced by 99.97 mass-%.

[0226] The dry SAN was subjected to 8 h of Soxhlet extraction using n-heptane. The bromine content was thereby reduced by 98.6% (total reduction by 99.8% compared with starting material).

[0227] FIG. 24 shows a photograph of the sample pellets before dissolution in MIBK (left) and a photograph of the decanted SAN solution and the ABS rubber separated therefrom by centrifugation (right).

[0228] FIG. 25 shows a photograph of the precipitation (left and center) and filtration (right) of the SAN from the decanted SAN solution.

[0229] Example 16 Example 15 was repeated, however the Soxhlet extraction step was replaced with filtration over a bed of activated carbon layered above a bed of Aluminum Oxide N in accordance with the procedure of Example 10.

[0230] The bromine content was thereby reduced by 95.4% (total reduction by 99.3% compared with starting material). The filtration is significantly faster than Soxhlet extraction, and the bromine content can be further reduced by repeating the filtration step.

[0231] Example 17

[0232] The SAN products obtained in the Examples are compounded with virgin ABS rubbers or the separated ABS rubbers obtained in the Examples as insoluble fractions, to obtain white or colored thermoplastic ABS-based polymer compositions, which are then used for preparing molded articles.

[0233] FIG. 26 shows photographs of sample plates and test bars obtained by compounding SAN products with ABS rubber in a DSM twin-screw compounder (50 rpm, 240 °C, 4 min run time, 17 g sample weight), from which the molten product was directly filled into a heated cylinder, from which the injection molding of plates and test bars with the DSM injection molder was performed (240 °C melt, 70 °C mold, 8 bar, 15 s injection time).

[0234] The photographs show commercial grade ABS articles (white; top left), virgin SAN compounded with ABS rubber (white; top right), SAN from Examples 8 (yellow; bottom left),

[0235] 9 (brown; bottom center) and 10 (white; bottom right) compounded with ABS rubber.

[0236] Example 18

[0237] 10 g of ABS waste from electrical and electronic equipment (WEEE-ABS; obtained from polymer waste sorting facility; ground to flakes) were mixed with 90 g of MIBK at room temperature for 16 h at 300 rpm using a laboratory stirrer with stirring rod, after which centrifugation for 20 min at 6500 G and for 20 min at 8500 G was carried out and the SAN solution was decanted from the insoluble fraction containing ABS rubber.

[0238] The decanted SAN solution was opaque and had a dark color (from fine carbon black) with a brownish-reddish tint (from dissolved colorants).

[0239] The solution was filtered using a thin column packed with 1.7 cm of Aluminium Oxide N (bottom layer) and 1 cm of activated carbon (top layer). The filtrate of the SAN solution was slightly turbid and slightly colored due to residual carbon black particles.

[0240] The carbon black particles were further removed by centrifugation for 20 min at 14000 G and decantation, or by filtration through fine filters, such as PTFE filters having a pore size between 0.1 and 0.5 pm. It is also possible to reduce the amount of residual carbon black, if the height of the Aluminium Oxide N layer is increased.

[0241] The filtrate can be further processed to isolate substantially transparent and colorless SAN.

[0242] FIG. 27 shows a photograph of the SAN solution after decantation but before filtration using the packed column.

[0243] FIG. 28 shows a photograph of the SAN solution after filtration using the packed column and additional centrifugation for 20 min at 14000 G. The carbon black particles are deposited at the bottom of the centrifugation vessel.

[0244] FIG. 29 shows a photograph of the SAN solution after filtration using the packed column (left), and after additional filtration using a 0.45 pm filter (center) and a 0.2 pm filter (right). Both filtrations removed substantial amounts of residual carbon black particles. After filtration through the 0.2 pm filter, the SAN solution was substantially clear and colorless.

[0245] Example 19

[0246] 10 g of ABS waste from electrical and electronic equipment (WEEE-ABS; obtained from polymer waste sorting facility; ground to flakes) were mixed with 90 g of MIBK and 0.5 g of activated carbon at room temperature for 16 h at 250 rpm using a KPG stirrer. In contrast to Example 18, the brownish-reddish tint (from dissolved colorants) was not observed, which indicated that soluble contaminants can already be removed during the dissolution step using activated carbon.

[0247] The resultant mixture was filtered using a folded paper filter (Schleicher und Schuell; Type 597 1 ) by gravity over the course of 2 days. The filtrate was substantially colorless but contained residual carbon black particles resulting in slight turbidity. No indications of dissolved colorants in the filtrates were observed.

[0248] Further centrifugation, filtration using columns containing Aluminium Oxide N and / or filtration through fine filters, such as PTFE filters having a pore size between 0.1 and 0.5 pm, can further reduce residual disperse particles and thus reduce turbidity. Example 20

[0249] 15 mL of a solution of black ABS sample (1.25 wt.-%) in ethyl acetate or MIBK were thoroughly mixed with 15 mL of a collector solvent selected from deionized water and ethylene glycol, followed by phase separation.

[0250] After phase separation, the black colorant remained in the upper ethyl acetate or MIBK phase containing the ABS. It is assumed that polar inorganic components, e.g. salts, are transferred to the bottom lower phase containing the deionized water or ethylene glycol.

[0251] FIG. 30 shows photographs of the mixtures after phase separation using ethyl acetate as the solvent component S, and deionized water (left) or ethylene glycol (right) as collector solvents.

[0252] FIG. 31 shows photographs of the mixtures after phase separation using MIBK as the solvent component S, and deionized water (left) or ethylene glycol (right) as collector solvents.

[0253] After phase separation, the upper phase can be further processed as in the preceding examples, to recover the SAN from the ABS sample.

[0254] Example 21

[0255] 15 mL of a solution of black ABS sample (1.25 wt.-%) in MIBK were thoroughly mixed with 15 mL of alkaline water as a collector solvent, prepared by dissolving 0.2 g NaOH in 15 g deionized water, followed by phase separation.

[0256] The majority of the black colorant (carbon black) was transferred to the aqueous phase. The turbidity and coloration of the organic phase containing polymeric components such as SAN was substantially reduced.

[0257] FIG. 32 shows a photograph of the mixture after phase separation using alkaline water as a collector solvent.

[0258] After phase separation, the upper phase can be further processed as in the preceding examples, to recover the SAN from the ABS sample. Due to the reduced amount of carbon black in the organic phase, the further separation steps are facilitated.

[0259] Example 22 10 mL of a solution of black ABS sample (2.5 wt.-%) in MIBK were thoroughly mixed with 10 mL or 20 mL of alkaline water as a collector solvent, prepared by dissolving 0.2 g NaOH per 15 g deionized water, followed by phase separation.

[0260] After phase separation, the black colorant remained in the upper MIBK phase containing the ABS. It is assumed that polar inorganic components, e.g. salts, are transferred to the bottom lower phase containing the deionized water. However, increased concentrations of the polymeric material in the organic phase seem to prevent transfer of the black colorant from the ABS sample to the aqueous phase, regardless of the amount of the alkaline water used as the collector solvent.

[0261] FIG. 33 shows photographs of the mixtures after phase separation using alkaline water as a collector solvent with higher concentrations of black ABS (left: 10 mL collector solvent; right: 20 mL collector solvent).

[0262] After phase separation, the upper phase can be further processed as in the preceding examples, to recover the SAN from the ABS sample.

[0263] Example 23

[0264] 10 mL of a solution of black ABS sample (2.5 wt.-%) in MIBK were thoroughly mixed with 10 of alkaline water as a collector solvent, prepared by dissolving 0.2 g NaOH per 15 g deionized water, and a drop of commercial dishwashing detergent, followed by phase separation.

[0265] The majority of the black colorant (carbon black) was transferred to the aqueous phase. After phase separation, the organic phase containing polymeric components such as SAN was only slightly turbid, and was hardly discolored, despite the increased concentration of the polymeric material in the organic phase, which was earlier shown to prevent transfer of black colorant to the aqueous phase.

[0266] FIG. 34 shows a photograph of the mixture after phase separation using alkaline water with detergent as a collector solvent.

[0267] After phase separation, the upper phase can be further processed as in the preceding examples, to recover the SAN from the ABS sample. Due to the reduced amount of carbon black in the organic phase, the further separation steps are facilitated.

[0268] Example 24 10 mL of a solution of black ABS sample (2.5 wt.-%) in MIBK were thoroughly mixed with 10 of alkaline water as a collector solvent, prepared by dissolving 0.2 g NaOH per 15 g deionized water, and a drop of a liquid surfactant mixture (consisting of 15 wt.-% sodium dodecyl sulfate and 5 wt.-% Tween 20 in deionized water), followed by phase separation.

[0269] The majority of the black colorant (carbon black) was transferred to an intermediate phase between the organic phase and the aqueous phase. After phase separation, the organic phase containing polymeric components such as SAN was only slightly turbid, and was slightly discolored, despite the increased concentration of the polymeric material in the organic phase, which was earlier shown to prevent transfer of black colorant to the aqueous phase.

[0270] FIG. 35 shows a photograph of the mixture directly after thorough mixing (left) after phase separation (right) using alkaline water with the liquid surfactant mixture as a collector solvent.

[0271] After phase separation, the upper phase can be further processed as in the preceding examples, to recover the SAN from the ABS sample. Due to the reduced amount of carbon black in the organic phase, the further separation steps are facilitated.

Claims

Claims1. A method of processing a thermoplastic polymer composition T, comprising the steps: a) mixing a thermoplastic polymer composition T, preferably post-consumer and / or post-industrial waste, comprisingA) at least one copolymer A comprisingA1) repeating units of at least one aromatic vinyl monomer A1 , preferably styrene, alpha-methyl styrene and / or p-methylstyrene, more preferably styrene;A2) repeating units of at least one vinyl cyanide monomer A2, preferably acrylonitrile and / or methacrylonitrile, more preferably acrylonitrile; andA3) optionally repeating units of further monomers A3 co-polymerizable with A1 and / or A2;B) at least one graft copolymer B comprisingB1) a rubbery core B1 obtained by polymerizingB11) at least 60% by weight, based on the total weight of the rubbery core B1 , of at least one conjugated diene and / or alkyl(meth)acrylate monomer B11 , preferably butadiene, isoprene, butyl acrylate and / or ethylhexyl acrylate, more preferably butadiene and / or butyl acrylate, more preferably butadiene;B12) optionally up to 40% by weight, based on the total weight of the rubbery core B1 , of monomers B12 copolymerizable with the conjugated diene and / or alkyl(meth)acrylate monomer B11 , preferably at least one aromatic vinyl monomer A1 and / or at least one vinyl cyanide monomer A2;B13) optionally up to 5% by weight, based on the total weight of the rubbery core B1 , of at least one cross-linking agent B13, preferably dicyclopentadienyl acrylate, tris-allyl isocyanurate, ethylene glycol di(meth)acrylate and / or allyl(meth)acrylate; and optionallyB2) a rubbery core B2 different from rubbery core B1 , preferably selected from silicone rubber and / or EPDM rubber; andB3) a polymeric shell B3, grafted to the rubbery core B1 and optionally the rubbery core B2, comprisingB31) repeating units of at least one aromatic vinyl monomer A1 ; and / or B32) repeating units of at least one vinyl cyanide monomer A2;C) at least one additive C from the group of colorants and flame retardants, more preferably at least one colorant, which is at least one pigment or dye; andD) optionally further components D different from A, B and C, preferably selected from the group comprisingD1) further polymers D1 ;D2) further additives D2; andD3) contaminants D3, such as organic residues, dirt, metals, paper and moisture; with at least one solvent component S, to obtain a mixture T1 and optionally a swollen and / or insoluble fraction T2; b) at least partially separating the swollen and / or insoluble fraction T2, if present, from the mixture T1 , preferably by gravimetric separation, filtration or a combination thereof, more preferably by gravimetric separation; c) at least partially separating soluble additives C1 and optionally further soluble components D-1 from the at least one copolymer A in mixture T 1 ; d) isolating a polymer composition T3 from the mixture T1 , preferably by removing solvent from the mixture T 1 obtained in step c); e) optionally isolating a polymer composition T4, preferably colored composition T4, from the swollen and / or insoluble fraction T2, f) optionally further processing of the polymer composition T3 and / or the polymer composition T4, preferably by drying, washing, extrusion and / or calendering; wherein the polymer composition T3 comprises not more than 50% by weight, preferably not more than 20% by weight, more preferably not more than 10% by weight of the components C and D present in the thermoplastic composition T, based on the total weight of components C and D.

2. The method according to claim 1 , wherein the at least one solvent component S is selected via Hansen Solubility Parameters (HSP), thus that the HSP distance (Ra) between the solvent component S and the at least one copolymer A is equal to or smaller than 13 jMPa, preferably from 5 to 13 MPa, more preferably from 7 to 13 MPa, more preferably from 10 to 13 jMPa, and / or wherein the Rabetween the at least one solvent component S and the at least one graft copolymer B is smaller than 12 jMPa, preferably from 4 to 12 jMPa, more preferably from 5 to 12 jMPa, more preferably from 6 to 11 .5jMPa, more preferably from 8.5 to 11 .5 ^jMPa.

3. The method according to claim 2, wherein the at least one solvent component S is a mixture of at least two solvents.

4. The method according to any one of claims 1 to 3, wherein the solvent component S is selected from the group consisting of ethers, esters, ketones, carbonate, hydrocar-bons, halogenated hydrocarbons, alcohols, aldehydes, nitriles, amides, aromatic substances, nitro-aromatic substances, halogenated aromatic substances, sulfoxides, lactones and mixtures thereof, preferably ethers, esters, ketones, carbonate, hydrocarbons, alcohols, aldehydes, nitriles, amides, aromatic substances, sulfoxides, lactones and mixtures thereof, more preferably ethers, esters, ketones, hydrocarbons and mixtures thereof.

5. The method according to any one of claims 1 to 4, wherein the solvent component S is selected from the group consisting of alkyl acetates, acetone, 2-butanone, methyl ethyl ketone, methyl isobutyl ketone, tert.-butyl methyl ketone, hydrocarbons, THF and mixtures thereof, preferably alkyl acetates, methyl ethyl ketone, methyl isobutyl ketone, tert.-butyl methyl ketone, THF and mixtures thereof.

6. The method according to any one of claims 1 to 5, wherein the separation of soluble additives C1 and optionally further soluble components D-1 in step c) comprises at least one step of sorption using at least one sorbent, preferably selected from activated carbon, aluminum oxide, calcium carbonate and silicon dioxide, which is preferably combined with filtration and / or gravimetric separation, preferably filtration.

7. The method according to any one of claims 1 to 6, wherein the swollen and / or insoluble fraction T2 is obtained in step a), and separated from the mixture T1 in step b).

8. The method according to any one of claims 1 to 7, wherein the isolation of the polymer composition T3, preferably removal of the solvent, in step d) comprises at least one step selected from precipitation of the polymer composition T3 with a precipitating agent, by evaporation, cooling, or a combination thereof.

9. The method according to any one of claims 1 to 8, wherein the at least one additive C, preferably at least one insoluble additive C2, more preferably at least one insoluble colorant, more preferably carbon black, and optionally further components D-2 at least partially remain sorbed to the graft copolymer B, and preferably wherein the graft copolymer B is at least partially separated from the mixture T1 in step b) and / or c), preferably as part of the swollen and / or insoluble fraction T2 in step b), more preferably wherein at least 50% by weight, more preferably at least 80% by weight, more preferably at least 90% by weight, more preferably at least 95% by weight of the insoluble additives C2 and insoluble further components D-2, based on the total weight of insoluble components C2 and D-2 present in the thermoplastic polymer composition T, are removed together with the graft copolymer B in step b).

10. The method according to any one of claims 1 to 9, wherein the separation of soluble additives C1 , preferably soluble colorants, and optionally further soluble components D-1 in step c) comprises sorption using activated carbon and sorption using an inorganic component, preferably aluminium oxide, preferably wherein at least 50% by weight, more preferably at least 80% by weight, more preferably at least 90% by weight, more preferably at least 95% by weight of the soluble additives C1 and optional further components D-1 , based on the total weight of soluble components C1 and D-1 originally present in the thermoplastic polymer composition T, are removed from the mixture T1 in step c).11 . The method according to any one of claims 1 to 10, wherein no precipitating agent is used in step d), preferably in the entire method.

12. The method according to any one of claims 1 to 11 , wherein the thermoplastic composition T comprises at least one additive C selected from flame retardants preferably halogenated flame retardants, and wherein the additives C other than colorants are separated from the swollen and / or insoluble fraction T2 and / or from the mixture T 1 .

13. The method according to any one of claims 1 to 12, wherein the thermoplastic composition T comprises:A) 10 to 89.99% by weight, based on the total weight of the thermoplastic composition T, of the at least one copolymer A comprisingA1) 40 to 99% by weight, based on the total weight of copolymer A, of the repeating units of at least one aromatic vinyl monomer A1 ;A2) 1 to 60% by weight, based on the total weight of copolymer A, of the repeating units of at least one vinyl cyanide monomer A2; andA3) 0 to 59% by weight, based on the total weight of copolymer A, of further monomers A3 copolymerizable with A1 and / or A2;B) 10 to 89.99% by weight, based on the total weight of the thermoplastic composition T, of the at least one graft copolymer B comprisingB1) 10 to 90% by weight, based on the total weight of graft copolymer B, of the rubbery core B1 ; andB3) 10 to 90% by weight, based on the total weight of graft copolymer B, of the polymeric shell B3 grafted on the rubbery core B1 , comprisingB31) 40 to 100% by weight, based on the total weight of the polymeric shell B3, of the repeating units of at least one aromatic vinyl monomer A1 and B32) 0 to 60% by weight, based on the total weight of the polymeric shell B3, of the repeating units of at least one vinyl cyanide monomer A2;C) 0.01 to 60% by weight, based on the total weight of the thermoplastic composition T, of the at least one additive C; andD) 0 to 60% by weight, based on the total weight of the thermoplastic composition T, of further components D.

14. The method according to any one of claims 1 to 13, wherein in step a) the thermoplastic composition T and the solvent component S are mixed in a weight ratio of from 1 :99 to 25:75, preferably from 2:98 to 15:85, more preferably from 5:95 to 12:88.

15. The method according to any one of claims 1 to 14, wherein the swollen and / or insoluble fraction T2 comprises at least a portion of the graft copolymer B and of the at least one additive C, preferably colorant, more preferably carbon black, sorbed to the graft copolymer B, and optionally of further components D sorbed to the graft copolymer B.

16. The method according to any one of claims 1 to 15, wherein the mixing of the thermoplastic polymer composition T and the solvent component S in step a) is carried out at a temperature of from 0 °C to the boiling point of the solvent component S, preferably from 10 to 100 °C, more preferably 15 to 80 °C, more preferably from 20 to 50 °C, provided the temperature does not exceed the boiling point of the solvent component S.

17. The method according to any one of claims 1 to 16, where another liquid is added as a collector solvent to the mixture of the thermoplastic polymer composition T and the solvent component S, characterized in that the collector solvent and the solvent component S are chosen such that the solvent phase comprising the thermoplastic polymer composition T is soluble preferably by less than 5 wt.-% in the collector solvent.

18. A thermoplastic polymer composition obtained by the method according to any one of claims 1 to 17, wherein the polymer composition is the polymer composition T3, the polymer composition T4, a mixture thereof, or a mixture of T3, T4 or both with virgin material.

19. A molded article comprising the thermoplastic polymer composition according to claim 18.

20. The use of the thermoplastic polymer composition according to claim 19 for the preparation of a molded article.

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