How to recycle ABS waste

Abstract

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

Description

Technical Field

[0001] Cross - reference to related applications This application claims the priority of U.S. Provisional Application No. 63 / 533,330, filed on August 17, 2023. This document is hereby incorporated by reference in its entirety.

[0002] Field This disclosure relates to the recycling of acrylonitrile - butadiene - styrene (ABS) waste. This disclosure relates to methods for recycling ABS waste. For example, this disclosure relates to methods for recycling ABS waste by recovering styrene - acrylonitrile polymer (SAN), optionally by number - average molecular weight (Mn). This disclosure relates to recycled SAN obtained from ABS waste and articles containing recycled SAN.

Background Art

[0003] ABS plastics exist in multiple grades for various applications and industries. ABS grades vary with the nature and amount of additives (e.g., flame retardants, fillers, other additives). At the same time, ABS plastics are also classified according to their inherent monomer ratios (e.g., acrylonitrile - to - styrene ratio in SAN, polybutadiene (PBU) - to - SAN ratio), monomer sequence arrangements (e.g., random distribution, alternating distribution or block distribution of monomers) and SAN size (molecular weight - Mw&Mn).

[0004] For health considerations, industries such as the healthcare and toy industries require high - specification grades from the perspectives of polymer Mw&Mn, acrylonitrile - styrene ratio, PBU - to - SAN ratio, and purity (e.g., additive levels).

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

[0006] The commonly used mechanical recycling of ABS is not suitable for producing high-grade polymers for use in demanding industries such as the toy industry because mechanical recycling increases polymer degradation.

[0007] Furthermore, used plastic raw materials often contain mixtures of materials from various sources (electronics, automotive, toy, and food industries, etc.) and various contaminants such as flame retardants and additives prohibited in high-end industries such as the toy industry. Used plastic raw materials also typically contain various Mn SANs and decomposed PBUs, which affect the properties and performance of recycled products.

[0008] Therefore, a better method is needed for recycling ABS waste. [Overview of the project]

[0009] As shown herein, SAN can be substantially selectively recovered as the primary fraction from ABS waste by dissolving ABS waste in a first SAN-selective solvent, such as a polar aprotic solvent. Furthermore, it is shown herein that the additional use of a second solvent that is more selective to SAN than to PBU, such as a nonpolar solvent (e.g., a nonpolar aromatic solvent) or a polar protic solvent, enables the recovery of SAN of higher purity than PBU and PBU-SAN copolymers. Moreover, it is shown herein that the Mn bracket of the recovered SAN can be adjusted by varying the ratio of the second solvent selective to SAN to the first SAN-selective solvent.

[0010] Therefore, in one embodiment, the present disclosure includes a method for recycling one or more polymer components from acrylonitrile butadiene styrene copolymer (ABS) waste, wherein the ABS waste includes polybutadiene (PBU), styrene acrylonitrile copolymer (SAN), and their copolymers, and the method includes the following: ABS waste is combined with a first SAN selective solvent to obtain an ABS waste mixture; Combining an ABS waste mixture with a second SAN selective solvent under conditions that maintain at least a portion of the SAN in solution and obtain a solid containing PBU, a copolymer of SAN and PBU, and the remaining portion of the SAN (if present); and To separate a solution containing at least a portion of a solid and SAN.

[0011] In another embodiment, the disclosure comprises recycled styrene-acrylonitrile 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 concentrations of about 0.01% w / w to about 17% w / w.

[0012] In another embodiment, the Disclosure includes recycled SAN of the Disclosure for use in the preparation of acrylonitrile butadiene styrene copolymer (ABS).

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

[0014] In another aspect, the Disclosure includes articles containing recycled SANs as described in the Disclosure. In another aspect, the Disclosure includes articles containing SANs recycled by the methods described in the Disclosure.

[0015] Embodiments of the present disclosure are described in more detail here with reference to the attached drawings. [Brief explanation of the drawing]

[0016] [Figure 1A-1F] Figure 1A shows photographs of the products at each step of the recycling process of ABS waste and used ABS flakes according to one embodiment of the method of the present disclosure. Figure 1B shows the used ABS waste raw material. Figure 1B shows polystyrene extracted using cymene extraction. Figure 1C shows other polymers, including insoluble polycarbonate and polypropylene, in an example of a polar aprotic solvent (e.g., ethyl acetate). Figure 1D shows insoluble particles removed by physical means such as filtration, centrifugation, and decantation. Figure 1E shows aggregated gel and high Mn SAN precipitated upon addition of a nonpolar solvent such as p-cymene. Figure 1F shows the precipitated SAN.

[0017] Other features and advantages of this disclosure will become apparent from the detailed description below. However, it should be understood that the detailed description and specific examples illustrate embodiments of this disclosure, but are given only as examples, and the claims should not be limited by these embodiments, but rather given the broadest interpretation consistent with the entire description. [Modes for carrying out the invention]

[0018] I. Definition Unless otherwise noted, the definitions and embodiments described in this and other sections are intended to be applicable to all embodiments and aspects of the Disclosure described herein to which they are applicable, as will be understood by those skilled in the art.

[0019] The term "and / or" in this specification means that the enumerated items exist or are used individually or in combination. In practice, the term means that "at least one" or "one or more" of the enumerated items are used or exist. The term "and / or" means that, with respect to its pharmaceutically acceptable salts and / or solvates, the compounds of the disclosure exist as individual salts and hydrates, as well as in combination thereof, for example, solvates of salts of the compounds of the disclosure.

[0020] In this disclosure, the singular forms “a, an” and “the” include plural references unless otherwise clearly indicated by the context. For example, “an embodiment containing a compound” should be understood to present a certain configuration having one compound or two or more additional compounds.

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

[0022] As used in this disclosure and the claims (if any), 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 of" and its derivatives as used herein are intended to be closed terms that identify the presence of the recited features, elements, components, groups, integers, and / or steps and exclude the presence of other unrecited features, elements, components, groups, integers and / or steps.

[0024] The term "consisting essentially of" as used herein is intended to identify the recited features, elements, components, groups, integers, and / or steps, and the presence of those that do not substantially affect the basic and novel characteristics (if any) 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 does not vary significantly. These terms of degree should be construed as including at least a ±5% deviation of the modified term, provided that such deviation does not negate the meaning of the word it modifies or the context does not otherwise suggest to one of ordinary skill in the art.

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

[0027] This document lists many chemical terms and abbreviations used by those skilled in the art. Nevertheless, definitions of selected terms are provided for clarity and consistency.

[0028] As used herein, the term "room temperature" refers to a temperature between approximately 20°C and 25°C.

[0029] As used herein, the term "ethylacetate" refers to ethyl acetate.

[0030] As used herein, the term "ABS" refers to acrylonitrile butadiene styrene copolymer. Generally, ABS is understood to include styrene acrylonitrile copolymer (SAN), polybutadiene (PBU), and copolymers of SAN and PBU. ABS may contain residual monomers such as styrene, butadiene, and acrylonitrile.

[0031] As used herein, the term "SAN" refers to styrene-acrylonitrile copolymer. A given SAN is intended to include copolymers of substantially uniform size (e.g., Mn) or a range of different sizes.

[0032] As used herein, the term "PBU" refers to polybutadiene.

[0033] As used herein, the term "FTIR" refers to Fourier transform infrared spectroscopy.

[0034] As used herein, the term "Mn" refers to the number-average molecular weight.

[0035] As used herein, the term “polar aprotic solvent” means a solvent that has moderate to relatively high polarity but does not contain hydrogen bond donors.

[0036] As used herein, the term "nonpolar solvent" refers to a solvent with moderate to relatively low polarity.

[0037] As used herein, the term “polar protic solvent” means a solvent that has moderate to relatively high polarity while containing at least one hydrogen bond donor.

[0038] As used herein, the term “first SAN selective solvent” refers to a solvent that can substantially selectively solubilize the majority of SAN in ABS waste compared to other components of the ABS waste (e.g., polymer components). The first SAN selective solvent can solubilize SAN regardless of the Mn content 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, but only a small portion of the PBU and crosslinked SAN-PBU copolymers, or substantially not them. For example, the first SAN selective solvent can solubilize substantially all of the uncrosslinked SAN-PBU copolymers in ABS waste. Such solvents have been found to 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] As used herein, the term “second SAN selective solvent” refers to a solvent that, when added to a solution of SAN, PBU, and / or SAN-PBU copolymer, substantially retains at least a portion of the SAN in the solution but phase-separates the PBU and SAN-PBU copolymer into another phase. For example, the solution of SAN, PBU, and SAN-PBU copolymer may be a solution obtained by combining a first SAN selective solvent with ABS waste.

[0040] II. Method of Disclosure In one embodiment, the Disclosure includes a method for recycling one or more polymer components from acrylonitrile butadiene styrene copolymer (ABS) waste, wherein the ABS waste includes polybutadiene (PBU), styrene acrylonitrile copolymer (SAN), and copolymers thereof, and the method includes: ABS waste is combined with a first SAN selective solvent to obtain an ABS waste mixture; Combining an ABS waste mixture with a second SAN selective solvent under conditions that maintain at least a portion of SAN in solution and yield a solid containing PBU, a copolymer of SAN and PBU, and the remaining portion of SAN (if present); and To separate a solution containing at least a portion of a solid and SAN.

[0041] In some embodiments, the method further comprises removing all insoluble portions, if present, from the ABS waste mixture, optionally including filtration, decantation, centrifugation, or a combination thereof. In some embodiments, removal is by filtration.

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

[0043] While we do not wish to be bound by theory, the intention is 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 and substantially all of the non-crosslinked copolymers of SAN and PBU in the ABS waste. It can be recognized that the copolymers of SAN and PBU in ABS may or may not be crosslinked. Therefore, in some embodiments, crosslinked PBU and SAN copolymers are 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] A second SAN selective solvent is assumed to be able to retain at least a portion of the SAN in solution while separating the PBU and PBU-SAN copolymer (e.g., uncrosslinked) into different phases. For example, the PBU and PBU-SAN copolymer (e.g., uncrosslinked) may form gel-like materials such as aggregated gels, which can be separated from the solution containing at least a portion of the SAN. The SAN can then be separated from other polymer components of the ABS waste by removing other components present in different phases. Solvents such as nonpolar solvents, polar aprotic solvents, and mixtures thereof are shown herein to be 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 ketones, amides, ethers, esters, carbonates, lactones, and combinations thereof, and 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 nonpolar solvent is selected from aromatic nonpolar solvents, alkanes, and combinations thereof. In some embodiments, the aromatic nonpolar solvent is selected from p-cymene, ethylbenzene, toluene, and mixtures thereof. In some embodiments, the alkane is C 6-10 Selected from alkanes and mixtures thereof. In some embodiments, the alkane is C 6-8 Alkanes and mixtures thereof are selected. 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, an alcohol, or a mixture thereof. In some embodiments, the alcohol is C 1-5 Alkanols and mixtures thereof are selected. In some embodiments, the alcohol is selected from methanol, ethanol, propanol, butanol, and mixtures thereof.

[0048] It is shown herein that a second SAN selective solvent will preferentially solubilize SAN with lower Mn, while SAN and PBU with higher Mn will undergo phase separation. On the other hand, a first SAN selective solvent will solubilize SAN regardless of its Mn. While we do not wish to be bound by theory, it is shown herein that adding the second SAN selective solvent of this disclosure alters the solubility of the resulting solvent mixture to a higher solubility for SAN with relatively lower Mn, while the resulting solvent mixture has lower solubility for SAN and SAN-PBU copolymers with higher Mn in the ABS waste. Thus, SAN with a desired Mn can be recovered from ABS waste by adjusting the ratio of the first and second SAN selective solvents. It can be noted that when more of the second SAN selective solvent is used in the method of this disclosure, the Mn of the recovered SAN tends to be lower. Conversely, when less of the second SAN selective solvent is used, the Mn of the recovered SAN tends to be closer to the average Mn of the ABS waste initiating material.

[0049] In some embodiments, the second SAN selective solvent is a nonpolar aromatic solvent. In some embodiments, the second SAN selective solvent is used in amounts of about 0.1 wt% to about 70 wt%, optionally about 10 wt% to about 65 wt%, or about 30 wt% to about 60 wt%, based on the weight of the first SAN selective solvent.

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

[0051] In some embodiments, the separation of solids and solutions includes filtration, decantation, centrifugation, flocculation, or a combination thereof, and optionally the separation is by filtration and / or centrifugation.

[0052] In some embodiments, the solid further comprises insoluble additives. In some embodiments, the insoluble additives include flame retardants, fillers, clays, carbonaceous particles, pigments, flame retardant synergens, and polybutadiene microgel particles.

[0053] While we do not wish to be bound by theory, it should be recognized that solubility can be affected by ambient temperature. For example, when an ABS waste mixture is combined with a second SAN selective solvent at a relatively high temperature, PBU and / or SAN-PBU copolymers, which are desirable to be phase-separated from the solution, may become more soluble. Therefore, 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, PBU and / or SAN-PBU copolymers, which have low solubility in the second SAN selective solvent, will become even less soluble, and therefore, a smaller amount of the second SAN selective solvent may be used.

[0054] It is intended that the second SAN selective solvent may be used in liquid form. For example, when the second SAN selective solvent is combined with the ABS waste mixture, it is intended that the solvent or solution portion of the resulting composition remains liquid, allowing for separation and phase separation of PBU and the PBU-SAN copolymer. Therefore, in some embodiments, the combination of the ABS waste mixture with the second SAN selective solvent is carried out at a temperature at which the solution portion of the resulting composition remains liquid. In some embodiments, the combination of the ABS waste mixture with the second SAN selective solvent is carried out at a temperature approximately the eutectic point of the first and second SAN selective solvents ~ the boiling point of the first SAN selective solvent, the boiling point of the second SAN selective solvent, and the lowest temperature of the mixture of the first and second SAN selective solvents in the case that the first and second SAN selective solvents form an azeotrope. In some embodiments, the combination of the ABS waste mixture with the second SAN selective solvent is carried out at a temperature of about 0°C to the lowest temperature of the boiling point of the first SAN selective solvent, the boiling point of the second SAN selective solvent, and the boiling point of the mixture of the first and second SAN selective solvents if the first and second SAN selective solvents form an azeotrope.

[0055] For example, if the first SAN selective solvent is ÃV and the second SAN selective solvent is p-cymene, the combination of the ABS waste mixture with the second SAN selective solvent may be carried out at a boiling point of about room temperature to about ÃV, or at a temperature of 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 combination of the ABS waste mixture with the second SAN selective solvent is carried out at about room temperature.

[0056] For example, if the first SAN selective solvent is à and the second SAN selective solvent is heptane, the combination of the ABS waste mixture with the second SAN selective solvent may be carried out at a boiling point of about room temperature to about Ã, or at a temperature of 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 combination of the ABS waste mixture with the second SAN selective solvent is carried out at about room temperature.

[0057] For example, if the first SAN selective solvent is acetone and the second SAN selective solvent is p-cymene, the combination of the ABS waste mixture with the second SAN selective solvent may 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 combination of the ABS waste mixture with the second SAN selective solvent is carried out at about room temperature.

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

[0059] In some embodiments, precipitation involves combining the solution with a hydrocarbon SAN nonsolvent. In some embodiments, the hydrocarbon SAN nonsolvent is an alkane, and optionally the alkane is C6-C6 10 Selected from alkanes and mixtures thereof.

[0060] In some embodiments, the method further includes washing the precipitated SAN with one or more portions of hydrocarbon SAN nonsolvent. In some embodiments, the washing is carried out at the boiling point of the hydrocarbon SAN nonsolvent, which optionally 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 parts of a mixture of hydrocarbon SAN non-solvent and a first SAN selective solvent. In some embodiments, the mixture of hydrocarbon SAN non-solvent and the first SAN selective solvent contains 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 being 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 cleaning is a continuous cleaning process.

[0063] In some embodiments, the method further includes drying the precipitated SAN.

[0064] In some embodiments, the ABS waste further comprises polystyrene (PS), and before combining the ABS waste with a first SAN selective solvent, the method further comprises the following: A combination of ABS waste with an aromatic nonpolar solvent to obtain a PS solution and solid ABS waste from which PS has been depleted; Separating PS-depleted solid ABS waste from PS solution; and Optionally, a PS solution may be combined with a hydrocarbon polystyrene non-solvent to obtain precipitated PS; and Combining ABS waste with a first SAN selective solvent is equivalent to combining PS-depleted solid ABS waste with a first SAN selective solvent.

[0065] In some embodiments, the hydrocarbon polystyrene nonsolvent is selected from C6-C8 alkanes and mixtures thereof, and optionally the hydrocarbon polystyrene nonsolvent is heptane.

[0066] In some embodiments, the combination of the ABS waste / aromatic nonpolar solvent mixture with a hydrocarbon polystyrene nonsolvent is carried out at the boiling point of the hydrocarbon polystyrene nonsolvent.

[0067] In some embodiments, the method further includes agglomerating the ABS waste mixture before combining it with a second SAN selective solvent, and optionally agglomerating the mixture as follows: 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 containing the ABS waste mixture and a solid waste residue; and To separate the supernatant containing the ABS waste mixture from the solid waste residue.

[0068] In some embodiments, the ABS waste includes polystyrene (PS), and the method further includes a solution containing at least a portion of SAN, after which the ABS waste mixture is combined with a second SAN selective solvent for agglomeration, and optionally includes the following: Heating the solution under acidic conditions, then adding a base, heating the solution under neutral conditions, then cooling the solution to obtain a supernatant containing the solution and solid waste residue; and Separating the supernatant containing the solution from 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, acidic conditions include pH values ​​of less than 5, about 2 to about 5, about 3.5 to about 4.5, or about 4. In some embodiments, acidic conditions are obtained by adding mineral acids, organic acids, or combinations thereof to an ABS waste mixture or a solution containing at least a portion of SAN; optionally, by adding one or more acids selected from HCl, H2SO4, acetic acid, formic acid, oxalic acid, adipic acid, and combinations thereof.

[0071] In some embodiments, the ABS waste mixture is heated to 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, a solution containing at least a portion of the SAN is heated to 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 used ABS waste.

[0074] III. Disclosed recycled SAN and its use In another embodiment, the disclosure includes recycled styrene-acrylonitrile copolymer (SAN) obtained from acrylonitrile butadiene styrene copolymer (ABS) waste, wherein the recycled SAN contains SAN, and the recycled SAN further contains polybutadiene (PBU) and / or PBU-SAN copolymer at concentrations 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 contains residual solvent at concentrations of about 10 ppm to about 10,000 ppm, the residual solvent being selected from p-cymene, ethylbenzene, toluene, ethyl acetate, butyl acetate, ethyl butyrate, 4-butanone, and mixtures thereof. In some embodiments, the residual solvent is present at concentrations of about 100 ppm to about 1,000 ppm.

[0076] In another embodiment, the Disclosure includes recycled SAN of the Disclosure for use in the preparation of acrylonitrile butadiene styrene copolymer (ABS).

[0077] In another embodiment, the Disclosure includes recycled SAN by the method of the Disclosure for use in the preparation of acrylonitrile butadiene styrene copolymer (ABS). In some embodiments, the preparation of ABS includes controlled blending and / or chemical polymerization.

[0078] In another aspect, the Disclosure includes articles containing recycled SANs as described in the Disclosure. In another aspect, the Disclosure includes articles containing SANs recycled by the methods described in the Disclosure.

[0079] Examples The following non-limiting embodiments are examples of the present disclosure.

[0080] General method All solvents were high-purity chromatography-grade and purchased from Sigma Aldrich. The X-ray fluorescence spectrophotometer used was a Bruker Titan™ S1. The FTIR was a Thermosfisher Nicolet™ is10; the quantification method was thoroughly investigated in-house. Molecular weight was measured in tetrahydrofuran using a WAT044228-Styragel™ HR 5E column on an Agilent 1260 Infinity™.

[0081] Example 1: Separation of SAN from post-industrial raw materials Two post-industrial ABS waste raw materials from different sources were recycled separately. The first raw material contained SAN with high Mn content, which is used for thermoforming applications (Raw Material 1). The second raw material was a commercial source of PC / ABS blends (Raw Material 2).

[0082] Test 1 - Recycling of Raw Material 1 100 g of raw material 1 was solubilized in ethyl acetate (¼) as an exemplary polar aprotic solvent at a ratio of 20 wt% to obtain a milky white solution. Two assays were performed. In the first assay, p-cymene (as an exemplary nonpolar solvent) was added with ¼ (w / w) in a 1:4 ratio (e.g., 20 wt% p-cymene based on the total weight of p-cymene and ¼) to obtain a final solution of raw material 1 at 16 wt% in the solvent mixture. In the second assay, p-cymene was added with ¼ (w / w) in a 1:1 ratio (e.g., 50 wt% based on the total weight of p-cymene and ¼) to obtain a final solution of raw material 1 at 10 wt% in the solvent mixture. In the first assay, the solution was centrifuged and the milky white supernatant was collected. In the second assay, phase separation was observed between an aggregated gel and a clear solution. The mixture was centrifuged and the clear solution was collected. In both cases, the milky supernatant from the first assay and the clear solution from the second assay were added to heptane at 90°C to obtain a 30% w / w milky supernatant or 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 as mostly SAN by FTIR. The SAN precipitate was washed with a heptane / siRNA mixture, followed by heptane, to extract residual p-cymene. The residual solvent was removed from the washed SAN precipitate by defoliation.

[0083] The results of the extraction of raw material 1 are shown in Table 1. As shown, the SAN recovered using either a nonpolar solvent versus a polar aprotic solvent ratio was significantly purer than the starting material in terms of PBU content. Furthermore, lower ratios of nonpolar solvent versus polar aprotic solvent resulted in the selective recovery of SAN having a higher average Mn. Therefore, the method of this disclosure can be adjusted to select a desired Mn by adjusting the ratio of nonpolar solvent versus polar protic solvent. [Table 1]

[0084] Test 2 - Recycling of Raw Material 2 100g of raw material 2 (PC / ABS) was solubilized with ethyl acetate at a 20 wt% concentration to obtain a milky white solution. Undissolved PC was removed by screening the solution on a mesh filter. p-cymene was added in a 1:1 ratio with ethyl acetate (w / w) (e.g., 50 wt% p-cymene based on the total weight of p-cymene and ethyl acetate) to obtain a final solution with the raw material concentration reduced by half. Phase separation was observed between the aggregated gel and the clear solution. The mixture was centrifuged. The clear solution (supernatant) was added to heptane at 90°C to obtain a clear solution with a 30% ratio (w / w) based on the total weight of the heptane mixture. A white precipitate was observed and collected. The precipitate was identified as SAN by FTIR, and its polycarbonate content was reduced by 97.5% compared to the raw material. The SAN precipitate was washed with the heptane / ethyl acetate mixture, followed by heptane, to extract residual p-cymene. The residual solvent was removed from the SAN precipitate by defoliation.

[0085] The results of the extraction of raw material 2 are shown in Table 2. [Table 2]

[0086] Note: * The PC band interferes with the PBU band. After eliminating the PC contribution, the resulting values ​​showed a 75.4% improvement using ABS.

[0087] Example 2 - Recovery of SAN from spent raw materials Three used raw materials were recycled using the method of this disclosure. The first ABS raw material (raw material 3) contained SAN used for injection molding (toys). Therefore, the Mn of SAN in raw material 3 is suitable for injection molding. The second ABS raw material (raw material 4) was derived from waste electrical and electronic equipment (WEEE) and contained a large amount of flame retardant and flame retardant synergist. The third raw material (raw material 5) was derived from thermoforming (automotive parts) and contained a large amount of other impurities such as other plastics (PS, PP) and inorganic compounds.

[0088] Test 1 - Recycling of Raw Material 3 Fine fragments of used multicolor toys (raw material 3) were used for this test. We aimed to demonstrate that the appropriate selection of solvent ratios leads to the required level of purification and to maintain the SAN molecular weight within the desired range for high-end applications such as those in the toy industry.

[0089] 100 g of raw material 3 was solubilized in ethyl acetate at 20 wt% to obtain a greenish-white solution. p-cymene was added in a 1:1 ratio with ethyl acetate (w / w) (e.g., 50 wt% p-cymene based on the total weight of p-cymene and ethyl acetate) to obtain a final solution of raw material 3 at 10 wt% in the solvent mixture. Phase separation was observed between an aggregated green gel and a clear solution. The mixture was centrifuged. The pale green translucent solution (supernatant) was added to heptane at 90°C to obtain a 30% w / w supernatant of the total weight of the resulting heptane mixture. A greenish precipitate was observed and collected. The precipitate was washed twice with the heptane / ethyl acetate mixture, followed by washing with heptane to extract residual color and p-cymene. Residual color and p-cymene were removed using the heptane / ethyl acetate mixture (70% / 30% w / w). The precipitate was identified as SAN by FTIR. The residual solvent was removed from the SAN precipitate by defoliation. [Table 3] [Table 4]

[0090] Test 2 - Recycling of Raw Material 4 Raw material 4 is used black ABS derived from WEEE, which was a fairly common and readily available raw material for waste ABS plastic. In its natural form using mechanical recycling methods, it cannot be recycled for use in the toy industry due to its high content of harmful elements (flame retardants, additives), pigments (e.g., pure black), and broad Mn distribution.

[0091] Raw material 4 was recycled using different proportions of p-cymene with the method of this disclosure, as described below.

[0092] In the first assay, p-cymene was not used. In the second assay, 40 wt% p-cymene was used based on the total weight of phosphate and p-cymene. In the third assay, 50 wt% p-cymene was used based on the total weight of phosphate and p-cymene.

[0093] 100g of black ABS WEEE waste (raw material 4) was solubilized with siRNA at 20 wt% to obtain a blackish-white solution. The solution was filtered to remove insoluble material. p-cymene was added at the specified ratio to obtain a final solution of raw material 4 at 10-20 wt% in the solvent mixture. Phase separation was observed between the aggregated gel and the brown solution when p-cymene was present. When 0% cymene was present, the aggregation procedure was applied. Alkaline pretreatment was applied, and the aggregated impurities were removed by centrifugation. After this first step, an acidic compound was added and neutralized with an alkaline compound to induce the formation of aggregates, which were separated from the main solution by centrifugation. After this aggregation step, a brownish-transparent solution was obtained. The brown solution was added to heptane at 90°C to obtain a 30% w / w brown solution. Grayish-white SAN precipitates were observed and collected in each case. The SAN precipitate was washed with a heptane / ethyl acetate mixture, followed by washing with heptane, to extract residual cymene. The residual solvent was removed from the SAN precipitate by defoliation. [Table 5]

[0094] Test 3 - Recovery of SAN from commercially available used ABS flake raw materials 5 Used ABS flakes are a raw material with a very low level of sorting and may contain a mixture of ABS from various sources (e.g., WEEE, household electrical appliances, automobiles). It contains very high percentages of other plastics such as polycarbonate (PC) and polypropylene (polypropylene) (PP) with fillers added. It is a fairly common and readily available raw material for ABS waste. In its natural form using current methods, it cannot be used as a recycled content for the toy industry due to its high content of other plastics (up to 60%), the presence of undesirable elements (e.g., flame retardants, additives), the use of pigments (e.g., mixed colors), and the wide Mn distribution of SAN.

[0095] Samples of used ABS waste were processed using the method of this disclosure. Due to the highly mixed nature of the raw materials, an optional step to extract PS and HIPS was performed first. The process was carried out and monitored at each step to quantify and identify the contaminants extracted along the recycling process.

[0096] 100 g of mixed used ABS flakes were immersed in p-cymene for 24 hours. The cymene-soluble portion containing polystyrene (PS and HIPS) was extracted by filtration. The remaining flakes were then immersed in 20 wt% ethyl acetate to dissolve the ABS. The solution was filtered using a 140 μm mesh filter to remove insoluble plastics. The solution was then centrifuged to further remove small insoluble particles. p-cymene was added in a 1:1 ratio with ethyl acetate (w / w) (e.g., 50 wt% based on the total weight of p-cymene and ethyl acetate). Phase separation was observed between the aggregated gel and the pale gray translucent solution. The pale gray translucent solution was extracted by centrifugation. The pale gray translucent solution was added to heptane at 90°C to reach a 30% ratio (w / w). The gray-to-white SAN precipitate was observed and collected. The SAN precipitate was washed with a heptane / ethyl acetate mixture, followed by washing with heptane, to extract residual cymene. The residual solvent was removed from the SAN precipitate by defoliation. [Table 6]

[0097] Figure 1 shows photographs of the ABS waste extracted at each step of the process.

[0098] Table 7 shows the material balance of methods for recycling used ABS. [Table 7]

[0099] Example 4 - Recovery of SAN using different pairs of polar aprotic and nonpolar solvents 100 g of mixed used ABS flakes were immersed in a suitable polar aprotic solvent (e.g., siRNA or acetone, see Table 8) at a concentration of 20 wt% to dissolve the ABS flakes. The solution was filtered using a 140 μm mesh filter to remove insoluble materials such as plastics (e.g., polypropylene (PP) and / or polycarbonate (PC)). The solution was then centrifuged to further remove small insoluble particles. A nonpolar solvent was added at a ratio of approximately 15–50% w / w based on the weight of the polar aprotic solvent used. Phase separation was observed between the aggregated gel and the 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 non-solvent such as heptane at approximately 70–90°C to a ratio of 30% w / w of the colored translucent solution based on the total weight of the resulting mixture. The white SAN precipitate was observed and collected. The SAN precipitate was washed with SAN non-solvent and a SAN non-solvent / polar aprotic solvent mixture to extract the residual nonpolar solvent. The residual solvent was removed from the SAN precipitate by defoliation. [Table 8]

[0100] As shown in the FTIR results in Table 8, all combinations of polar aprotic and nonpolar solvents tested allowed for selective recovery of SAN (shown as PS+PAN in FTIR) with very low amounts of PBU.

[0101] While this disclosure has been described with reference to examples, it should be understood that the claims should not be limited by the embodiments specified in the examples, but rather should be given the broadest possible interpretation consistent with the overall description.

[0102] All publications, patents, and patent applications are incorporated herein by reference to the same extent that each individual publication, patent, or patent application is specifically and individually indicated as being incorporated by reference in whole. Where any term in this disclosure is found to be defined differently in a document incorporated herein by reference, the definitions provided herein shall serve as the definitions for that term.

Claims

1. A method for recycling one or more polymer components from acrylonitrile butadiene styrene copolymer (ABS) waste, wherein the ABS waste comprises polybutadiene (PBU), styrene acrylonitrile copolymer (SAN), and copolymers thereof. To obtain an ABS waste mixture, the ABS waste is combined with a first SAN selective solvent; Combining the ABS waste mixture with a second SAN-selective solvent under conditions to obtain a solid containing at least a portion of the SAN in solution and the copolymer of the PBU, SAN, and PBU, and the remaining portion of the SAN, if present; and To separate the solid from the solution containing at least a portion of the SAN. Methods that include...

2. The method according to claim 1, further comprising removing all insoluble portions, if present, from the ABS waste mixture, optionally including filtration, decantation, centrifugation, or a combination thereof, and optionally the removal by filtration.

3. The method according to claim 2, wherein the insoluble portion comprises an insoluble polymer, optionally selected from polycarbonate, polypropylene, polyethylene, and combinations thereof.

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

5. The method according to any one of claims 1 to 4, wherein the first SAN selective solvent is selected from ketones, amides, ethers, esters, carbonates, lactones, and combinations thereof, and 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 according to any one of claims 1 to 5, wherein the second SAN-selective solvent is a nonpolar solvent, a polar protic solvent, or a mixture thereof.

7. The method according to claim 6, wherein the nonpolar solvent is selected from nonpolar aromatic solvents, alkanes, and combinations thereof, and optionally the nonpolar aromatic solvent is selected from p-cymene, ethylbenzene, toluene, and combinations thereof, and optionally the alkane is selected from cyclohexane, hexane, pentane, octane, and combinations thereof.

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

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

10. The method according to 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, and optionally in an amount of about 10 wt% to about 65 wt%, or about 30 wt% to about 60 wt%,

11. The method according to any one of claims 8 to 10, wherein the second SAN-selective solvent is the alkane and / or the polar protic solvent.

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

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

14. The method according to any one of claims 1 to 13, wherein the solid further comprises an insoluble additive, optionally the insoluble additive comprising a flame retardant, a filler, clay, carbonaceous particles, a pigment, a flame retardant synergist, or polybutadiene microgel particles.

15. The method according to any one of claims 1 to 14, wherein the ABS waste mixture is combined with the second SAN selective solvent at a temperature between the eutectic points of the first SAN selective solvent and the second SAN selective solvent and the boiling point of the first SAN selective solvent, the boiling point of the second SAN selective solvent, and, if present, the boiling point of the azeotropic mixture of the first SAN selective solvent and the second SAN selective solvent, the lowest temperature of the mixture.

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

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

18. The method according to claim 17, wherein the precipitation includes combining the solution with a hydrocarbon SAN nonsolvent.

19. The hydrocarbon SAN nonsolvent is an alkane, and optionally the alkane is C ６ ~C １０ The method according to claim 18, selected from alkanes and mixtures thereof.

20. The method according to any one of claims 17 to 19, further comprising washing the precipitated SAN with one or more of the hydrocarbon SAN nonsolvent.

21. The method according to claim 20, wherein the washing is carried out at the boiling point of the hydrocarbon SAN nonsolvent, and 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 according to claim 20, further comprising 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 according to 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 according to claim 22 or 23, wherein the washing is carried out at the boiling point of the mixture, and 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 according to any one of claims 20 to 24, wherein the cleaning is continuous cleaning.

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

27. The ABS waste further comprises polystyrene (PS), and before combining the ABS waste with the first SAN selective solvent, To obtain a PS solution and solid ABS waste from which PS has been depleted, the ABS waste is combined with the aromatic nonpolar solvent; To separate the PS-depleted solid ABS waste from the PS solution; and To obtain precipitated PS, optionally combine the PS solution with a hydrocarbon polystyrene non-solvent. Further including; and The method according to any one of claims 1 to 26, wherein combining the ABS waste with the first SAN selective solvent means combining the PS-depleted solid ABS waste with the first SAN selective solvent.

28. The aforementioned hydrocarbon polystyrene nonsolvent is C ６ ~C ８ The method according to claim 27, wherein the non-solvent of the hydrocarbon polystyrene is selected from alkanes and mixtures thereof, and optionally the non-solvent of the hydrocarbon polystyrene is heptane.

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

30. The method further includes agglomerating the ABS waste mixture before combining it with the second SAN selective solvent, and optionally, the agglomeration is performed. 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 and solid waste residue containing the ABS waste mixture; and To separate the supernatant containing the ABS waste mixture from the solid waste residue. The method according to any one of claims 1 to 29, including the method described in any one of claims 1 to 29.

31. The method according to claim 30, wherein the base is selected from potassium hydroxide, calcium hydroxide, ammonia, hexamethylenediamine, and combinations thereof.

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

33. The aforementioned acidic conditions are achieved by adding mineral acids, organic acids, or combinations thereof to the ABS waste mixture; optionally HCl, H ２ SO ４ The method according to any one of claims 30 to 32, obtained by adding one or more acids selected from acetic acid, formic acid, oxalic acid, adipic acid, and combinations thereof.

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

35. The ABS waste comprises polystyrene (PS), and the ABS waste mixture is further agglomerated after being combined with the second SAN selective solvent, and the agglomeration is optionally performed. Heating the solution under acidic conditions, then adding a base, heating the solution under neutral conditions, then cooling the solution to obtain a supernatant containing the solution and solid waste residue; and Separating the supernatant containing the solution from the solid waste residue. The method according to any one of claims 1 to 29, including the method described in any one of claims 1 to 29.

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

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

38. The aforementioned acidic conditions are achieved by adding a mineral acid, an organic acid, or a combination thereof to the solution; optionally HCl, H ２ SO ４ The method according to any one of claims 35 to 37, obtained by adding one or more acids selected from acetic acid, formic acid, oxalic acid, adipic acid, and combinations thereof.

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

40. The method according to any one of claims 1 to 39, wherein the ABS waste is used ABS waste.

41. Recycled styrene-acrylonitrile copolymer (SAN) comprising SAN and further comprising polybutadiene (PBU) and / or PBU-SAN copolymer in concentrations 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 according to claim 41, further comprising a residual solvent at a concentration of approximately 10 ppm to approximately 10,000 ppm, optionally, approximately 100 ppm to approximately 1,000 ppm, wherein the residual solvent is selected from p-cymene, ethylbenzene, toluene, ethyl acetate, butyl acetate, ethyl butyrate, 4-butanone, and mixtures thereof.

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

44. The preparation of ABS comprises controlled blending and / or chemical polymerization, wherein the recycled SAN for use is as described in claim 43.

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

46. The article according to claim 45, which is selected from toys, automotive parts, consumer goods, insulating materials, and electronic components, wherein the electronic components are optionally selected from mobile phone casings, TV casings, and computer casings.

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