Methods of recycling abs waste

Abstract

The present disclosure relates to the recycling of acrylonitrile butadiene styrene (ABS) waste. The present disclosure relates to methods for recycling ABS waste. For example, the present disclosure relates to methods of recycling ABS waste by recovering styrene acrylonitrile polymer (SAN), optionally by molecular weight (MW). The present disclosure relates to a recycled SAN obtained from ABS waste and articles comprising the recycled SAN.

Description

METHODS OF RECYCLING ABS WASTECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U. S. provisional application No. 63 / 533,330 filed on August 17, 2023. This document is hereby integrated by reference in its entirety.FIELD

[0002] The present disclosure relates to the recycling of acrylonitrile butadiene styrene (ABS) waste. The present disclosure relates to methods for recycling ABS waste. For example, the present disclosure relates to methods of recycling ABS waste by recovering styrene acrylonitrile polymer (SAN), optionally by number average molecular weight (Mn). The present disclosure relates to a recycled SAN obtained from ABS waste and articles comprising the recycled SAN.INTRODUCTION

[0003] ABS plastic exists in multiple grades for various applications and industries. The ABS grades vary with the nature and amount of additives (e.g. flame retardant, fillers, other additives). At the same time, ABS plastic is also graded according to its intrinsic monomers ratio (e.g. acrylonitrile to styrene ratio in SAN, polybutadiene (PBU) to SAN ratio), monomer sequential arrangement (e.g. random distribution, alternate distribution or block distribution of monomers) and SAN size (molecular weight- Mw & Mn).

[0004] Due to health considerations, industries, such as healthcare and toy industry, require high specification grade in terms of polymers Mw & Mn, Acrylonitrile styrene ratio, PBU to SAN ratio, and in terms of purity (e.g. level of additives).

[0005] In the current recycling industry, ABS waste is not widely recycled or reused. The recycling of ABS faces many challenges. For instance, plastic products’ long lifetime leads to inherent chain and additive degradation. It is well recognized that the PBU component of ABS suffer more degradation than the SAN component from aging and UV light exposition, leading to ABS plastic brittleness.

[0006] The commonly used mechanical recycling of ABS is not suitable for generating high grade polymers for use in exigent industries such as toy industry, since mechanical recycling will increase polymer degradation.

[0007] Moreover, post-consumer plastic feedstock often contains a mixture of materials from various origins (electronic, automotive, toys and food industry, etc.) and includes a variety of contaminants such as flame retardants and additives prohibited in high- end industries such as toy industry. Post-consumer plastic feed stock also typically contains SAN of various Mn, and degraded PBU which will impact properties and performance of the recycled product.

[0008] Accordingly, there is a need for a better method for recycling ABS waste.SUMMARY

[0009] As shown herein, by dissolving ABS waste in a first SAN selective solvent, for example a polar aprotic solvent, SAN can be substantially selectively recovered from the ABS waste as a major fraction. Moreover, it has been shown herein that additional use of a second solvent selective for SAN over PBU, for example a non-polar solvent (e.g. non-polar aromatic solvent), or a polar protic solvent, allows for recovery of SAN of higher purity over PBU and PBU-SAN copolymers. Further, it is shown herein that by varying the ratio of the second solvent selective for SAN and the first SAN selective solvent, the Mn bracket of the SAN recovered can be tailored.

[0010] Accordingly, in one aspect, the present disclosure includes a method of recycling one or more polymer components from acrylonitrile butadiene styrene copolymer (ABS) waste, the ABS waste comprising polybutadiene (PBU), styrene acrylonitrile copolymer (SAN), and copolymers thereof, wherein the method comprises combining the ABS waste with a first SAN selective solvent to obtain an ABS waste mixture; combining the ABS waste mixture with a second SAN selective solvent under conditions to maintain at least a portion of the SAN in a solution and to obtain a solid comprising the PBU, the copolymer of SAN and PBU, and a remaining portion of SAN if present; andseparating the solid and the solution comprising the at least a portion of the SAN.

[0011] In another aspect, the present disclosure includes a recycled styreneacrylonitrile copolymer (SAN) obtained from acrylonitrile butadiene styrene copolymer (ABS) waste, wherein the recycled SAN comprises SAN, and the recycled SAN further comprises polybutadiene (PBU) and / or PBU-SAN copolymer at a concentration of about 0.01 % w / w to about 17% w / w.

[0012] In another aspect, the present disclosure includes a recycled SAN of the present disclosure for use in the preparation of acrylonitrile butadiene styrene copolymer (ABS).

[0013] In another aspect, the present disclosure includes a SAN recycled by a method of the present disclosure for use in the preparation of acrylonitrile butadiene styrene copolymer (ABS).

[0014] In another aspect, the present disclosure includes an article comprising a recycled SAN of the present disclosure. In another aspect, the present disclosure includes an article comprising a SAN recycled by a method of the present disclosure.DRAWINGS

[0015] The embodiments of the disclosure will now be described in greater detail with reference to the attached drawings in which:

[0016] Figures 1 A, 1 B, 1 C, 1 D, 1 E and 1 F show photos of ABS waste and products at each step of a recycling process of post-consumer ABS flakes according to an embodiment of the methods of the present disclosure. Figure 1A shows the post-consumer ABS waste feedstock. Figure 1 B shows polystyrene extracted using cymene extraction. Figure 1 C shows other polymers containing polycarbonate and polypropylene insoluble in an example polar aprotic solvent (e.g. ethyl acetate). Figure 1 D shows insoluble particles eliminated by physical means such as filtration, centrifugation, decantation. Figure 1 E shows flocculated gel and high Mn SAN that was precipitated upon addition of non-polar solvent such as p- cymene. Figure 1 F shows the precipitated SAN.

[0017] Other features and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detaileddescription and the specific examples, while indicating embodiments of the disclosure, are given by way of illustration only and the scope of the claims should not be limited by these embodiments, but should be given the broadest interpretation consistent with the description as a whole.DESCRIPTION OF VARIOUS EMBODIMENTSI. Definitions

[0018] Unless otherwise indicated, the definitions and embodiments described in this and other sections are intended to be applicable to all embodiments and aspects of the present disclosure herein described for which they are suitable as would be understood by a person skilled in the art.

[0019] The term “and / or” as used herein means that the listed items are present, or used, individually or in combination. In effect, this term means that “at least one of’ or “one or more” of the listed items is used or present. The term “and / or” with respect to pharmaceutically acceptable salts and / or solvates thereof means that the compounds of the disclosure exist as individual salts and hydrates, as well as a combination of, for example, a solvate of a salt of a compound of the disclosure.

[0020] As used in the present disclosure, the singular forms “a”, “an” and “the” include plural references unless the content clearly dictates otherwise. For example, an embodiment including “a compound” should be understood to present certain aspects with one compound, or two or more additional compounds.

[0021] In embodiments comprising an “additional” or “second” component, such as an additional or second compound, the second component as used herein is chemically different from the other components or first component. A “third” component is different from the other, first, and second components, and further enumerated or “additional” components are similarly different.

[0022] As used in this disclosure and claim(s), the words "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "include" and "includes") or "containing" (and any form of containing, such as "contain" and "contains"), are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

[0023] The term “consisting” and its derivatives as used herein are intended to be closed terms that specify the presence of the stated features, elements, components, groups, integers, and / or steps, and also exclude the presence of other unstated features, elements, components, groups, integers and / or steps.

[0024] The term “consisting essentially of”, as used herein, is intended to specify the presence of the stated features, elements, components, groups, integers, and / or steps as well as those that do not materially affect the basic and novel characteristic(s) of these features, elements, components, groups, integers, and / or steps.

[0025] The terms "about", “substantially” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies or unless the context suggests otherwise to a person skilled in the art.

[0026] The term “non-solvent” for a particular substance as used herein means to a compound or a mixture of compounds in which the substance is substantially insoluble. For example, a polystyrene non-solvent refers to a compound ora mixture of compounds in which a polystyrene polymer is substantially insoluble. For example, a hydrocarbon polystyrene non-solvent refers to a hydrocarbon or a mixture of hydrocarbons in which one or more polystyrene polymers are substantially insoluble in.

[0027] The present description refers to a number of chemical terms and abbreviations used by those skilled in the art. Nevertheless, definitions of selected terms are provided for clarity and consistency.

[0028] The term “room temperature” as used herein refers to about 20°C to about 25°C.

[0029] The term “EtOAc” as used herein refers to ethyl acetate.

[0030] The term “ABS” as used herein refers to acrylonitrile butadiene styrene copolymer. It is understood that generally, ABS comprises styrene acrylonitrile copolymer (SAN), polybutadiene (PBU), and copolymers of SAN and PBU. It is also possible that the ABS may contain residual monomers such as styrene, butadiene and acrylonitrile.

[0031] The term “SAN” as used herein refers to styrene acrylonitrile copolymer. It is contemplated that a given SAN can comprise copolymers of substantially uniform size (e.g. Mn), or a range of different sizes.

[0032] The term “PBU” as used herein refers to polybutadiene.

[0033] The term “FTIR” as used herein refers to Fourier transform infrared spectroscopy.

[0034] The term “Mn” as used herein refers to number average molecular weight”.

[0035] The term “polar aprotic solvent” as used herein means a solvent of medium to relatively high polarity while does not contain hydrogen bond donor.

[0036] The term “non-polar solvent” as used herein means a solvent of medium to relatively low polarity.

[0037] The term “polar protic solvent” as used herein means a solvent of medium to relatively high polarity while containing at least one hydrogen bond donor.

[0038] The term “first SAN selective solvent” as used herein refers to a solvent that can substantially selectively solubilize the majority of the SAN in an ABS waste over other components (e.g. polymer components) of the ABS waste. The first SAN selective solvent can solubilize SAN regardless of the Mn of the SAN. For example, the first SAN selective solvent can solubilize substantially all, or at least 90%, at least 80%, at least 70% or at least 60% of the SAN while only solubilizing a minimal portion of or substantially not solubilizing the PBU and the crosslinked SAN PBU copolymer. For example, the first SAN selective solvent can solubilize substantially all of the non-crosslinked SAN PBU copolymer in the ABS waste. It has been found that such solvents include polar aprotic solvents. Such polar aprotic solvents include but are not limited to ethyl acetate, acetone, ethyl butyrate, butyl acetate, 4- butanone, or mixtures thereof.

[0039] The term “second SAN selective solvent” as used herein refers to a solvent that when added to a solution of SAN, PBU, and / or SAN PBU copolymers, would substantially maintain at least a portion of the SAN in solution while phase separate the PBU and SAN PBU copolymer into another phase. For example, the solution of SAN, PBU, and SAN PBUcopolymer can be a solution obtained from combining a first SAN selective solvent and an ABS waste.II. Methods of the Disclosure

[0040] In one aspect, the present disclosure includes a method of recycling one or more polymer components from acrylonitrile butadiene styrene copolymer (ABS) waste, the ABS waste comprising polybutadiene (PBU), styrene acrylonitrile copolymer (SAN), and copolymers thereof, wherein the method comprises combining the ABS waste with a first SAN selective solvent to obtain an ABS waste mixture; combining the ABS waste mixture with a second SAN selective solvent under conditions to maintain at least a portion of the SAN in a solution and to obtain a solid comprising the PBU, the copolymer of SAN and PBU, and a remaining portion of SAN if present; and separating the solid and the solution comprising the at least a portion of the SAN.

[0041] In some embodiments, the method further comprises removing any insoluble portion if present from the ABS waste mixture, optionally the removing comprises filtration, decantation, centrifugation, or combinations thereof. In some embodiments, the removing is by filtration.

[0042] In some embodiments, the insoluble portion comprises insoluble polymer, optionally, the insoluble polymers are selected from polycarbonate, polypropylene, polyethylene, and combinations thereof.

[0043] Without wishing to be bound by theory, it is contemplated that the first SAN selective solvent can solubilize the majority (e.g., at least 50%, at least 60%, at least 70%, at least 80%, or at least 90%) or substantially all of the SAN in the ABS waste and substantially all non-crosslinked copolymer of SAN and PBU. It can be appreciated that in general copolymers of SAN and PBU in ABS can be crosslinked or non-crosslinked. Therefore, in some embodiments, the crosslinked PBU and SAN copolymer is not solubilized in the first SAN selective solvent and can be removed from the ABS waste mixture by physical means including filtration, flocculation, decantation, centrifugation, and combinations thereof.

[0044] It is envisioned that the second SAN selective solvent can maintain at least a portion of the SAN in solution, while separating the PBU and PBU SAN copolymer (e.g. noncrosslinked) into a different phase. For example, the PBU and PBU SAN copolymer (e.g. non-crosslinked) can become a gel-like material, such as a flocculated gel, which can be separated from the solution containing the at least a portion of the SAN. The SAN can then be separated from the other polymer components of the ABS waste by removing the other components that are in a different phase. It has been shown herein that solvents such as non-polar solvents, polar aprotic solvents, and mixtures thereof are suitable second SAN selective solvents.

[0045] In some embodiments, the first SAN selective solvent is a non-halogenated solvent. In some embodiments, the first SAN selective solvent is selected from ketone, amide, ether, ester, carbonate, lactone, and combinations thereof, optionally, the first SAN selective solvent is selected from ethyl acetate, butyl acetate, ethyl butyrate, 2-butanone, tetrahydrofuran, acetone, N,N, -Dimethylformamide, acetonitrile, dimethyl sulfoxide and combinations thereof.

[0046] In some embodiments, the non-polar solvents are selected from aromatic nonpolar solvents, alkanes, and combinations thereof. In some embodiments, the aromatic nonpolar solvents are selected from p-cymene, ethyl benzene, toluene, and mixtures thereof. In some embodiments, the alkanes are selected from Ce-io alkanes, and mixtures thereof. In some embodiments, the alkanes are selected from Ce-s alkanes, and mixtures thereof. In some embodiments, the alkanes are linear. In some embodiments, the alkanes are branched. In some embodiments, the alkanes are selected from cyclohexane, hexane, pentane, octane, and mixtures thereof.

[0047] In some embodiments, the polar protic solvent is water, alcohol or mixtures thereof. In some embodiments, the alcohol is selected from C1-5 alkanol and mixtures thereof. In some embodiments, the alcohol is selected from methanol, ethanol, propanol, butanol, and mixtures thereof.

[0048] It has been shown herein that the second SAN selective solvent preferentially solubilizes SAN of lower Mn, while the SAN of higher Mn and PBU would phase separate. On the other hand, the first SAN selective solvent would solubilize the SAN regardless of itsMn. Without wishing to be bound by theory, it is shown herein that adding the second SAN selective solvent of the present disclosure changes the dissolution capacity of the resulting solvent mixture toward a higher solubility for SAN of relatively lower Mn, whereas the resulting solvent mixture has a lower solubility for SAN of high Mn and copolymers of SAN- PBU thereof an ABS waste. Accordingly, SAN of a desired Mn can be recovered from an ABS waste by adjusting the ratio of the first SAN selective solvent and the second SAN selective solvent. It can be appreciated that when more second SAN selective solvent is used in the methods of the present disclosure, the lower the Mn of the recovered SAN tends to be. Inversely, when less second SAN selective solvent is used, the Mn of the recovered SAN tends to be closer to the average Mn of the ABS waste starting material.

[0049] In some embodiments, the second SAN selective solvent is the non-polar aromatic solvent. In some embodiments, the second SAN selective solvent is used in an amount of about 0.1 wt% to about 70 wt% based on the weight of the first SAN selective solvent, optionally in an amount of about 10 wt% to about 65 wt%, about 30 wt% to about 60 wt%.

[0050] In some embodiments, the second SAN selective solvent is the alkanes and / or the polar protic solvent. In some embodiments, the second SAN selective solvent is used in an amount of about 0.1 wt% to about 15 wt% based on the weight of the first SAN selective solvent, optionally in an amount of about 0.1 wt% to about 10 wt%, about 1 wt% to about 5 wt%.

[0051] In some embodiments, the separating of the solid and the solution comprises filtration, decantation, centrifugation, flocculation, or combinations thereof, optionally the separating is by filtration and / or centrifugation.

[0052] In some embodiments, the solid further comprises insoluble additives. In some embodiments, the insoluble additives comprise flame retardants, fillers, clay, carbonaceous particles, pigments, flame retardant synergist, polybutadiene microgel particles.

[0053] Without wishing to be bound by theory, it can be appreciated that solubility can be affected by the ambient temperature. For instance, If the ABS waste mixture is combined with the second SAN selective solvent at a relatively high temperature, the PBU and / or SAN PBU copolymers that are desired to phase separate from the solution may become moresoluble. Accordingly, a higher proportion of the second SAN selective solvent may be used. If the temperature at which the ABS waste mixture is combined with the second SAN selective solvent is relatively low, the PBU and / or SAN PBU copolymer that have a low solubility in the second SAN selective solvent would be even less soluble, thus, less second SAN selective solvent may be used.

[0054] It is contemplated that the second SAN selective solvent can be used in liquid form. For example, it is contemplated that once the second SAN selective solvent is combined with the ABS waste mixture, the solvent or solution portion of the resulting composition would remain liquid to allow for separation with the phase separated PBU and PBU SAN copolymer. Therefore, in some embodiments, the combining of the ABS waste mixture with the second SAN selective solvent is carried out at a temperature that allows the solution portion of the resulting composition to remain liquid. In some embodiment, the combining of the ABS waste mixture with the second SAN selective solvent is carried out at a temperature of about a eutectic point of the first SAN selective solvent and the second SAN selective solvent to about the lowest of a boiling point of the first SAN selective solvent, a boiling point of the second SAN selective solvent, and a boiling point of a mixture the first SAN selective solvent and the second SAN selective solvent in the case where the first SAN selective solvent and the second SAN selective solvent form an azeotrope. In some embodiments, the combining of the ABS waste mixture with the second SAN selective solvent is carried out at a temperature of about 0°C to about the lowest of a boiling point of the first SAN selective solvent, a boiling point of the second SAN selective solvent, and a boiling point of a mixture the first SAN selective solvent and the second SAN selective solvent in the case where the first SAN selective solvent and the second SAN selective solvent form an azeotrope. In some embodiments, the combining of the ABS waste mixture with the second SAN selective solvent is carried out at a temperature of about room temperature to about the lowest of a boiling point of the first SAN selective solvent, a boiling point of the second SAN selective solvent, and a boiling point of a mixture the first SAN selective solvent and the second SAN selective solvent in the case where the first SAN selective solvent and the second SAN selective solvent form an azeotrope .

[0055] For example, when the first SAN selective solvent is EtOAc, and the second SAN selective solvent is p-cymene, the combining of the ABS waste mixture with the secondSAN selective solvent can be carried out at a temperature of about room temperature to about the boiling point of EtOAc, or about room temperature to about 77°C or about room temperature to about 70°C, or about room temperature to about 50°C. In some embodiments, the combining of the ABS waste mixture with the second SAN selective solvent is carried at about room temperature.

[0056] For example, when the first SAN selective solvent is EtOAc, and the second SAN selective solvent is heptane, the combining of the ABS waste mixture with the second SAN selective solvent can be carried out at a temperature of about room temperature to about the boiling point of EtOAc, or about room temperature to about 77°C or about room temperature to about 70°C, or about room temperature to about 50°C. In some embodiments, the combining of the ABS waste mixture with the second SAN selective solvent is carried at about room temperature.

[0057] For example, when the first SAN selective solvent is acetone, and the second SAN selective solvent is p-cymene, the combining of the ABS waste mixture with the second SAN selective solvent can be carried out at a temperature of about room temperature to about the boiling point of acetone, or about room temperature to about 56°C or about room temperature to about 50°C, or about room temperature to about 40°C. In some embodiments, the combining of the ABS waste mixture with the second SAN selective solvent is carried at about room temperature.

[0058] In some embodiments, the method further comprises precipitating the SAN from the solution comprising the at least a portion of the SAN to obtain precipitated SAN.

[0059] In some embodiments, the precipitating comprises combining the solution with a hydrocarbon SAN non-solvent. In some embodiments, the hydrocarbon SAN non-solvent is an alkane, optionally the alkane is selected from Ce to C10 alkanes and mixtures thereof.

[0060] In some embodiments, the method further comprises washing the precipitated SAN with one or more portions of the hydrocarbon SAN non-solvent. In some embodiments, the washing is carried out at the boiling point of the hydrocarbon SAN non-solvent, optionally the boiling point of the hydrocarbon SAN non-solvent is about 50°C to about 125°C, about 85°C to about 120°C, about 90°C to about 115°C, or about 100°C to about 115°C.

[0061] In some embodiments, the method further comprises washing the precipitated SAN with one or more portions of a mixture of the hydrocarbon SAN non-solvent and the first SAN selective solvent. In some embodiments, the mixture of the hydrocarbon SAN nonsolvent and the first SAN selective solvent comprises about 20 wt% of the first SAN selective solvent based on the total weight of the mixture. In some embodiments, the washing is carried out at the boiling point of the mixture, optionally the boiling point of the mixture is about 50°C to about 125°C, about 85°C to about 120°C, about 90°C to about 115°C, or about 100°C to about 115°C

[0062] In some embodiments, the washing is continuous washing.

[0063] In some embodiments, the method further comprises drying the precipitatedSAN.

[0064] In some embodiments, the ABS waste further comprises polystyrene (PS), and wherein prior to the combining of the ABS waste with the first SAN selective solvent, the method further comprises combining the ABS waste with an aromatic non-polar solvent to obtain a PS solution and a PS-depleted solid ABS waste; separating the PS-depleted solid ABS waste from the PS solution; and optionally combining the PS solution with a hydrocarbon polystyrene non-solvent to obtain precipitated PS; and wherein the combining of the ABS waste with the first SAN selective solvent is combining the PS depleted solid ABS waste with the first SAN selective solvent.

[0065] In some embodiments, the hydrocarbon polystyrene non-solvent is selected from Ce to Cs alkane, and mixtures thereof, optionally the hydrocarbon polystyrene nonsolvent is heptane.

[0066] In some embodiments, the combining of the ABS waste / aromatic non-polar solvent mixture with the hydrocarbon polystyrene non-solvent is carried out at a boiling point of the hydrocarbon polystyrene non-solvent.

[0067] In some embodiments, the method further comprises prior to the combining of the ABS waste mixture with the second SAN selective solvent, flocculating the ABS waste mixture, optionally the flocculating comprises heating the ABS waste mixture under acidic conditions, then adding a base, heating the ABS waste mixture under neutral conditions, then cooling the mixture to obtain a supernatant comprising the ABS waste mixture and a solid waste residue; and separating the supernatant comprising the ABS waste mixture from the solid waste residue.

[0068] In some embodiments, the ABS waste comprises polystyrene (PS), and the method further comprises after the combining of the ABS waste mixture with the second SAN selective solvent, flocculating the solution comprising the at least a portion of the SAN, optionally the flocculating comprises heating the solution under acidic conditions, then adding a base, heating the solution under neutral conditions, then cooling the solution to obtain a supernatant comprising the solution and a solid waste residue; and separating the supernatant comprising the solution from the solid waste residue.

[0069] In some embodiments, the base is selected from potassium hydroxide, calcium hydroxide, ammonia, hexamethylenediamine, and combinations thereof.

[0070] In some embodiments, the acidic conditions comprise a pH of less than 5, about 2 to about 5, about 3.5 to about 4.5 or about 4. In some embodiments, the acidic conditions are obtained by adding a mineral acid, an organic acid or combinations thereof, to the ABS waste mixture or to the solution comprising the at least a portion of the SAN; optionally by adding one or more acids selected from HCI, H2SO4, acetic acid, formic acid, oxalic acid, adipic acid, and combinations thereof.

[0071] In some embodiments, the ABS waste mixture is heated at a temperature of about 60°C to about 70°C, about 70°C to about 90°C, or about 80°C.

[0072] In some embodiments, the solution comprising the at least a portion of the SAN is heated at a temperature of about 60°C to about 70°C, about 70°C to about 90°C, or about 80°C.

[0073] In some embodiments, the ABS waste is post-consumer ABS waste.III. Recycled SAN of the Disclosure and Uses thereof

[0074] In another aspect, the present disclosure includes a recycled styreneacrylonitrile copolymer (SAN) obtained from acrylonitrile butadiene styrene copolymer (ABS) waste, wherein the recycled SAN comprises SAN, and the recycled SAN further comprises polybutadiene (PBU) and / or PBU-SAN copolymer at a concentration of about 0.01 % w / w to about 25% w / w. In some embodiments, the concentration of PBU and / or PBU-SAN copolymer is about 0,01 % w / w to about 15% w / w, about 0,01 % w / w to about 10% w / w, or about 0.01 % w / w to about 5% w / w.

[0075] In some embodiments, the recycled SAN further comprises a residual solvent at a concentration of about 10 ppm to about 10000 ppm, wherein the residual solvent is selected from p-cymene, ethylbenzene, toluene, ethyl acetate, butyl acetate, ethyl butyrate, 4-butanone, and mixture thereof. In some embodiments, the residual solvent is comprised at a concentration of about 100 ppm to about 1000 ppm.

[0076] In another aspect, the present disclosure includes a recycled SAN of the present disclosure for use in the preparation of acrylonitrile butadiene styrene copolymer (ABS).

[0077] In another aspect, the present disclosure includes a SAN recycled by a method of the present disclosure for use in the preparation of acrylonitrile butadiene styrene copolymer (ABS). In some embodiments, the preparation of ABS comprises controlled- blending and / or a chemical polymerisation.

[0078] In another aspect, the present disclosure includes an article comprising a recycled SAN of the present disclosure. In another aspect, the present disclosure includes an article comprising a SAN recycled by a method of the present disclosure.EXAMPLES

[0079] The following non-limiting examples are illustrative of the present disclosure.General Methods

[0080] All solvents are chromatography grade with a high purity and purchased from Sigma Aldrich. The X-ray fluorescence spectrophotometer used was a Bruker Titan™ S1. The FTIR is Nicolet™ is10 from Thermosfisher; the quantification method has been elaborated in house. The molecular weight was measured on an Agilent 1260 Infinity™ with a WAT044228 - Styragel™ HR 5E column, in tetrahydrofuran.

[0081] Example 1 Separation of SAN from post-industrial feedstock

[0082] Two post-industrial ABS waste feedstock of different sources were recycled each separately. The first feedstock comprised a SAN with high Mn that is used for thermoforming application (Feedstock 1 ). The second feedstock was a commercial source of PC / ABS blend (Feedstock 2).

[0083] Test 1 - Recycling of Feedstock 1

[0084] 100g of Feedstock 1 was solubilized in ethyl acetate (EtOAc) as an exemplary polar aprotic solvent at 20 wt% to obtain a milky solution. Two assays were performed. In the first assay, p-cymene (as an exemplary non-polar solvent) was added at a 1 :4 ratio with EtOAc (w / w) (e.g. 20 wt% p-cymene based on total weigh of p-cymene and EtOAc) leading to a final solution of 16wt% Feedstock 1 in solvent mixture. In the second assay, p-cymene was added at a 1 :1 ratio with EtOAc (w / w) (e.g. 50 wt% based on total weigh of p-cymene and EtOAc) leading to a final solution of 10wt% Feedstock 1 in solvent mixture. In the first assay, the solution was centrifuged, and a milky supernatant collected. In the second assay, a phase separation was observed between a flocculated gel and a clear solution. The mixture was centrifuged and the clear solution collected. In both cases, the milky supernatant of the first assay and the clear solution of the second assay were each added to heptane at 90°C to reach a 30% ratio (w / w) of the milky supernatant or the clear solution based on the total weight of the heptane mixture. A white precipitate was observed and collected in both cases. The precipitate was identified to be mostly SAN by FTIR. The SAN precipitate was washed by heptane / EtOAc mixture followed by heptane to extract residual p-cymene. Residual solvent was removed from the washed SAN precipitate by devolatilization.

[0085] Results of extraction of Feedstock 1 are shown in Table 1. As shown, the recovered SAN using either ratio of non-polar solvent to polar aprotic was significantly purer compared to the starting material feedstock in terms of PBU content. Further, a lower ratio of non-polar solvent to polar aprotic solvent led to selective recovery of SAN with higher average Mn. Therefore, the method of the present disclosure can be adjusted to select for a desired Mn by adjusting the ratio of non-polar solvent to the polar protic solvent.Table 1 - Extraction of SAN from post-industrial feedstocks

[0086] Test 2 - Recycling of Feedstock 2

[0087] 100g of Feedstock 2 (PC / ABS) was solubilized in EtOAc at 20 wt% to obtain a milky solution. The non dissolved PC was removed by screening the solution on mesh filter. P-cymene is added at a 1 :1 ratio with EtOAc (w / w) (e.g. 50 wt% p-cymene based on total weigh of p-cymene and ethyl acetate) leading to a final solution where the feedstock concentration has been reduced by half. A phase separation was observed between a flocculated gel and a clear solution. The mixture was centrifuged. The clear solution (supernatant) was added to heptane at 90°C to reach a 30% ratio (w / w) of the clear solution based on total weight of heptane mixture. A white precipitate was observed and collected. The precipitate was identified to be SAN by FTIR with reduction of 97.5% of polycarbonate content as compared to feedstock. The SAN precipitate was washed by heptane / EtOAc mixture followed by heptane to extract residual p-cymene. Residual solvent was removed from the SAN precipitate by devolatilization.

[0088] Results of extraction of Feedstock 2 are shown in Table 2.Table 2 - Extraction of SAN from post-industrial feedstocks 2.0089] Note: * PC band interferes with PBU band. Those values where obtained after elimination of PC contribution leading to a retrofit of 75.4% with ABS.Example 2 - Recovery of SAN from Postconsumer Feedstock

[0090] Three postconsumer feedstocks were recycled using the methods of the present disclosure. The first ABS feedstock (Feedstock 3) contained a SAN used for injection molding (toys). Thus, the Mn of the SAN in Feedstock 3 is suitable for injection molding. The second ABS feedstock (Feedstock 4) was from waste electronical and electrical equipment (WEEE), and included large quantity of flame retardant and flame retardant synergist. The third feedstock (Feedstock 5) was from thermoforming (Automotive parts) and contained large amount of contamination such as other plastic (PS, PP) and inorganic compounds.

[0091] Test 1 - Recycling of Feedstock 3

[0092] Postconsumer multicolor toys’ shred (Feedstock 3) was used for this test. We aimed to demonstrate that the proper selection of solvent ratio led to needed level of purification and maintain SAN molecular weight within the desired range for high end application such as toys industry.

[0093] 100g of Feedstock 3 was solubilized in EtOAc at 20 wt% to obtain a green milky solution. P-cymene is added at a 1 :1 ratio with EtOAc (w / w) (e.g. 50 wt% p-cymene based on total weigh of p-cymene and EtOAc) leading to a final solution of 10wt% Feedstock 3 in solvent mixture. A phase separation was observed between a flocculated green gel and a clear solution. The mixture was centrifuged. The light green translucent solution (supernatant) was added to heptane at 90°C to reach a 30% w / w of supernatant in total weight of resulting heptane mixture. A greenish precipitate was observed and collected. The precipitated was twice washed with heptane / EtOAc mixture followed by heptane to extract the residual color and p-cymene. A heptane / EtOAc mixture (70% / 30% w / w) was used toremove residual color and p-cymene. The precipitate was identified to be SAN by FTIR. Residual solvent was removed from the SAN precipitate by devolatilization.Table 3 - Extraction of SAN from post-consumer Feedstocks 3.Table 4 - XRF analysis of feedstock and recovered SAN from post-consumer feedstocks 3

[0094] Test 2 - Recycling of Feedstock 4

[0095] Feedstock 4 was postconsumer black ABS from WEEE, which was a fairly common and available feedstock of waste ABS plastic. In its native form using mechanical recycling methods, it cannot be recycled for use in the toy industry due to high content of harmful elements (flame retardant, additives), pigments (e.g. full black colour) and broad Mn distribution.

[0096] Feedstock 4 was recycled using methods of the present disclosure using different proportions of p-cymene as described below.

[0097] In a first assay, no p-cymene was used. In a second assay, 40wt% p-cymene based on the total weight of EtOAc and p-cymene was used. In a third assay, 50wt% p- cymene based on the total weight of EtOAc and p-cymene was used.

[0098] 100g black ABS WEEE waste (Feedstock 4) was solubilized in EtOAc at 20wt% to obtain a black milky solution. Solution was filtered to remove insoluble materials. P- cymene was added at defined ratios leading to a final solution of 10 to 20wt% Feedstock 4in the solvent mixture. A phase separation was observed between a flocculated gel and a brown solution for cases including p-cymene. For the case including 0% cymene a flocculation procedure was applied. An alkaline pretreatment was applied and the flocculated impurities were removed by centrifugation. After this first step, acidic compound was added and neutralized with alkaline compound leading to the formation of a flocculate, which was separated from main solution by centrifugation. After this flocculation step, a brown translucent solution was obtained. The brown solution was added to heptane at 90°C to reach a 30% w / w of brown solution. A grey to white SAN precipitate was observed and collected in each case. The SAN precipitate was washed by heptane / EtOAc mixture followed by heptane to extract residual cymene. Residual solvent was removed from the SAN precipitate by devolatilization.Table 5 - Analysis of feedstock and recovered SAN from post-consumer WEEE feedstocks 4

[0099] Test 3 - Recovery of SAN from Commercial Post-consumer ABS FlakesFeedstock 5

[0100] Postconsumer ABS flakes are feedstock with very low level of sorting and can contain mix of ABS from various origins (e.g. WEEE, home appliance, automotive). It contains a very high proportion of other plastics such as polycarbonate (PC) andpolyproppylene (PP) loaded with filler. It is a fairly common and available feedstock of ABS waste. In its native form using current methods, it cannot be used as recycled content for toy industry due to high content of other plastics (up to 60%), presence of undesirable elements (e.g. flame retardant, additives), use of pigments (e.g. mix colour) and broad Mn distribution of SAN.

[0101] A sample of post-consumer ABS waste was treated using the methods of the present disclosure. Due to the highly mixed nature of the feedstock, an optional step of extracting PS and HIPS was performed first. The process was performed and monitored at each step to quantify and identify contamination extracted along the recycling process.

[0102] 100g of mixed post-consumer ABS flake was soaked into p-cymene for 24h.The cymene-soluble portion containing polystyrene (PS and HIPS) was extracted by filtration. Residual flakes were then soaked in EtOAc at 20wt% to dissolve the ABS. The solution was filtrated with 140 urn mesh filter to remove insoluble plastics. Then the solution was centrifuged to further remove small insoluble particles. P-cymene is added at a 1 :1 ratio with EtOAc (w / w) (e.g. 50 wt% based on total weigh of p-cymene and EtOAc). A phase separation was observed between a flocculated gel and a light grey translucent solution. The light grey translucent solution was extracted by centrifugation. The light grey translucent solution was added to heptane at 90°C to reach a 30% ratio (w / w). A grey to white SAN precipitate was observed and collected. The SAN precipitate was washed by heptane / EtOAc mixture followed by heptane to extract residual cymene. Residual solvent was removed from the SAN precipitate by devolatilization.Table 6 - Analysis of SAN from post-consumer mixed feedstocks 5

[0103] Pictures of extracted ABS waste at each step of the process are shown in Figure 1 .

[0104] Mass balance of the method of recycling post-consumer ABS is shown in TableTable 7 - Mass balance of the method of the present disclosureExample 4 - Recovery of SAN using different couple of polar aprotic and non-polar solvent

[0105] 100g of mixed post-consumer ABS flake was soaked into a suitable polar aprotic solvent (e.g. EtOAc or acetone, see for example Table 8) at 20wt% to dissolve the ABS flake. The solution was filtered with 140 pm mesh filter to remove insoluble material such as plastics (e.g. polypropylene (PP) and / or polycarbonate (PC)). Then, the solution was centrifuged to further remove small Insoluble particles. A non-polar solvent was added at a ratio of about 15 to about 50% w / w based on the weight of the polar aprotic solvent used. A phase separation was observed between a flocculated gel and a colored translucent solution. The colored translucent solution was extracted by centrifugation or filtered through media assisted filtration. The colored translucent solution was added to a hydrocarbon SAN nonsolvent such as heptane at about 70 to about 90°C to reach a 30% w / w ratio of colored translucent solution based on total weight of the resulting mixture. A white SAN precipitate was observed and collected. The SAN precipitate was washed by SAN non-solvent and SAN non-solvent / polar aprotic solvent mixture to extract residual non-polar solvent. Residual solvent was removed from the SAN precipitate by devolatilization.Table 8 - Analysis of SAN recovered from various solvent mixture.PAN = polyacrylonitrile

[0106] As demonstrated in the FTIR results shown in Table 8, all combinations of polar aprotic solvent and non-polar solvent tested allowed for selective recovery of SAN (shown in FTIR as PS + PAN) with very low amount of PBU.

[0107] While the present disclosure has been described with reference to examples, it is to be understood that the scope of the claims should not be limited by the embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

[0108] All publications, patents and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety. Where a term in the present disclosure is found to be defined differently in a document incorporated herein by reference, the definition provided herein is to serve as the definition for the term.

Claims

CLAIMS:

1. Method of recycling one or more polymer components from acrylonitrile butadiene styrene copolymer (ABS) waste, the ABS waste comprising polybutadiene (PBU), styrene acrylonitrile copolymer (SAN), and copolymers thereof, wherein the method comprises combining the ABS waste with a first SAN selective solvent to obtain an ABS waste mixture; combining the ABS waste mixture with a second SAN selective solvent under conditions to maintain at least a portion of the SAN in a solution and to obtain a solid comprising the PBU, the copolymer of SAN and PBU, and a remaining portion of SAN if present; and separating the solid and the solution comprising the at least a portion of the SAN.

2. The method of claim 1 , wherein the method further comprises removing any insoluble portion if present from the ABS waste mixture, optionally the removing comprises filtration, decantation, centrifugation, or combinations thereof, optionally the removing is by filtration.

3. The method of claim 2, wherein the insoluble portion comprises insoluble polymer, optionally, the insoluble polymers are selected from polycarbonate, polypropylene, polyethylene, and combinations thereof.

4. The method of any one of claims 1 to 3, wherein the first SAN selective solvent is a non-halogenated solvent.

5. The method of any one of claims 1 to 4, wherein the first SAN selective solvent is selected from ketone, amide, ether, ester, carbonate, lactone, and combinations thereof, optionally, the first SAN selective solvent is selected from ethyl acetate, butyl acetate, ethyl butyrate, 2-butanone, tetrahydrofuran, acetone, N,N, -Dimethylformamide, acetonitrile, dimethyl sulfoxide and combinations thereof.

6. The method of any one of claims 1 to 5, wherein the second SAN selective solvent is a non-polar solvent, a polar protic solvent, or mixtures thereof.

7. The method of claim 6, wherein the non-polar solvent is selected from non-polar aromatic solvent, alkanes, and combinations thereof, optionally, the non-polar aromatic solvent is selected from p-cymene, ethyl benzene, toluene, and combinations thereof, and optionally wherein the alkanes are selected from cyclohexane, hexane, pentane, octane, and combinations thereof.

8. The method of claim 6 or 7, wherein the polar protic solvent is selected from alcohols, water, and combinations thereof, optionally, the polar protic solvent is selected from water, butanol, propanol, ethanol, methanol, and combinations thereof.

9. The method of claim 7 or 8, wherein the second SAN selective solvent is the nonpolar aromatic solvent.

10. The method of claim 9, wherein the second SAN selective solvent is used in an amount of about 0.1 wt% to about 70 wt% based on the weight of the first SAN selective solvent, optionally in an amount of about 10 wt% to about 65 wt%, about 30 wt% to about 60 wt%.11 . The method of any one of claims 8 to 10, wherein the second SAN selective solvent is the alkanes and / or the polar protic solvent.

12. The method of claim 11 , wherein the second SAN selective solvent is used in an amount of about 0.1 wt% to about 15 wt% based on the weight of the first SAN selective solvent, optionally in an amount of about 0.1 wt% to about 10 wt%, about 1 wt% to about 5 wt%.

13. The method of any one of claims 1 to 12, wherein the separating of the solid and the solution comprises filtration, decantation, centrifugation, flocculation, or combinations thereof, optionally the separating is by filtration and / or centrifugation.

14. The method of any one of claims 1 to 13, wherein the solid further comprises insoluble additives, optionally the insoluble additives comprise flame retardants, fillers, clay, carbonaceous particles, pigments, flame retardant synergist, polybutadiene microgel particles.

15. The method of any one of claims 1 to 14, wherein the combining of the ABS waste mixture with the second SAN selective solvent is carried out at a temperature of a eutectic point of the first SAN selective solvent and the second SAN selective solvent to about the lowest of a boiling point of the first SAN selective solvent, a boiling point of the second SAN selective solvent and a boiling point of an azeptropic mixture of the first SAN selective solvent and the second SAN selective solvent if any.

16. The method of any one of claims 1 to 14, wherein the combining of the ABS waste mixture with the second SAN selective solvent is carried out at a temperature of about room temperature to about the lowest of a boiling point of the first SAN selective solvent, a boiling point of the second SAN selective solvent, and a boiling point of any azeptropic mixture of the first SAN selective solvent and the second SAN selective solvent.

17. The method of any one of claims 1 to 16, wherein the method further comprises precipitating the SAN from the solution comprising the at least a portion of the SAN to obtain precipitated SAN.

18. The method of claim 17, wherein the precipitating comprises combining the solution with a hydrocarbon SAN non-solvent.

19. The method of claim 18, wherein the hydrocarbon SAN non-solvent is an alkane, optionally the alkane is selected from Ce to C10 alkanes and mixtures thereof.

20. The method of any one of claim 17 to 19, wherein the method further comprises washing the precipitated SAN with one or more portions of the hydrocarbon SAN non-solvent.21 . The method of claim 20, wherein the washing is carried out at the boiling point of the hydrocarbon SAN non-solvent, optionally the boiling point of the hydrocarbon SAN nonsolvent is about 50°C to about 125°C, about 85°C to about 120°C, about 90°C to about 115°C, or about 100°C to about 115°C.

22. The method of claim 20, wherein the method further comprises washing the precipitated SAN with one or more portions of a mixture of the hydrocarbon SAN non-solvent and the first SAN selective solvent.

23. The method of claim 22, wherein the mixture of the hydrocarbon SAN non-solvent and the first SAN selective solvent comprises about 20 wt% of the first SAN selective solvent based on the total weight of the mixture.

24. The method of claim 22 or 23, wherein the washing is carried out at the boiling point of the mixture, optionally the boiling point of the mixture is about 50°C to about 125°C, about 85°C to about 120°C, about 90°C to about 115°C, or about 100°C to about 115°C.

25. The method of any one of claims 20 to 24, wherein the washing is continuous washing.

26. The method of any one of claims 20 to 25, wherein the method further comprises drying the precipitated SAN.

27. The method of any one of claims 1 to 26, wherein the ABS waste further comprises polystyrene (PS), and wherein prior to the combining of the ABS waste with the first SAN selective solvent, the method further comprises combining the ABS waste with an aromatic non-polar solvent to obtain a PS solution and a PS-depleted solid ABS waste; separating the PS-depleted solid ABS waste from the PS solution; and optionally combining the PS solution with a hydrocarbon polystyrene non-solvent to obtain precipitated PS; and wherein the combining of the ABS waste with the first SAN selective solvent is combining the PS depleted solid ABS waste with the first SAN selective solvent.

28. The method of claim 27, wherein the hydrocarbon polystyrene non-solvent is selected from Ce to Cs alkane, and mixtures thereof, optionally the hydrocarbon polystyrene nonsolvent is heptane.

29. The method of claim 27 or 28, wherein the combining of the ABS waste / aromatic nonpolar solvent mixture with the hydrocarbon polystyrene non-solvent is carried out at a boiling point of the hydrocarbon polystyrene non-solvent.

30. The method of any one of claims 1 to 29, wherein the method further comprises prior to the combining of the ABS waste mixture with the second SAN selective solvent, flocculating the ABS waste mixture, optionally the flocculating comprises heating the ABS waste mixture under acidic conditions, then adding a base, heating the ABS waste mixture under neutral conditions, then cooling the mixture to obtain a supernatant comprising the ABS waste mixture and a solid waste residue; and separating the supernatant comprising the ABS waste mixture from the solid waste residue.31 . The method of claim 30, wherein the base is selected from potassium hydroxide, calcium hydroxide, ammonia, hexamethylenediamine, and combinations thereof.

32. The method of claim 30 or 31 , wherein the acidic conditions comprise a pH of less than 5, about 2 to about 5, about 3.5 to about 4.5 or about 4.

33. The method of any one of claims 30 to 32, wherein the acidic conditions are obtained by adding a mineral acid, an organic acid or combinations thereof, to the ABS waste mixture; optionally by adding one or more acids selected from HCI, H2SO4, acetic acid, formic acid, oxalic acid, adipic acid, and combinations thereof.

34. The method of any one of claims 30 to 33, wherein the ABS waste mixture is heated at a temperature of about 60°C to about 70°C, about 70°C to about 90°C, or about 80°C.

35. The method of any one of claims 1 to 29, wherein the ABS waste comprises polystyrene (PS), and the method further comprises after the combining of the ABS waste mixture with the second SAN selective solvent, flocculating the solution comprising the at least a portion of the SAN, optionally the flocculating comprises heating the solution under acidic conditions, then adding a base, heating the solution under neutral conditions, then cooling the solution to obtain a supernatant comprising the solution and a solid waste residue; and separating the supernatant comprising the solution from the solid waste residue.

36. The method of claim 35, wherein the base is selected from potassium hydroxide, calcium hydroxide, ammonia, hexamethylenediamine, and combinations thereof.

37. The method of claim 35 or 36, wherein the acidic conditions comprise a pH of less than 5, about 2 to about 5, about 3.5 to about 4.5 or about 4.

38. The method of any one of claims 35 to 37, wherein the acidic conditions are obtained by adding a mineral acid, an organic acid or combinations thereof, to the solution; optionally by adding one or more acids selected from HCI, H2SO4, acetic acid, formic acid, oxalic acid, adipic acid, and combinations thereof.

39. The method of any one of claims 35 to 38, wherein the solution is heated at a temperature of about 60°C to about 70°C, about 70°C to about 90°C, or about 80°C.

40. The method of any one of claims 1 to 39, wherein the ABS waste is post-consumer ABS waste.

41. A recycled styrene-acrylonitrile copolymer (SAN), wherein the recycled SAN comprises SAN, and the recycled SAN further comprises polybutadiene (PBU) and / or PBU- SAN copolymer at a concentration of about 0.01 % w / w to about 25% w / w, about 0,01 % w / w to about 15% w / w, about 0,01 % w / w to about 10% w / w, or about 0.01 % w / w to about 5% w / w.

42. The recycled SAN of claim 41 , wherein the recycled SAN further comprises a residual solvent at a concentration of about 10 ppm to about 10000 ppm, optionally about 100 ppm to about 1000 ppm, wherein the residual solvent is selected from p-cymene, ethylbenzene, toluene, ethyl acetate, butyl acetate, ethyl butyrate, 4-butanone, and mixture thereof.

43. The recycled SAN of claim 41 or 42, or a SAN recycled by a method as defined in any one of claims 1 to 40 for use in the preparation of acrylonitrile butadiene styrene copolymer (ABS).

44. The recycled SAN for use of claim 43, wherein the preparation of ABS comprises control blending and / or a chemical polymerisation.

45. An article comprising a recycled SAN as defined in claim 41 or 42 or a SAN recycled by a method as defined in any one of claims 1 to 40.

46. The article of claim 45, wherein the article is selected from a toy, automotive parts, consumer goods, insulation material, electronic parts, optionally the electronic parts are selected from cell phone casing, TV casing, and computer casing.

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