Recovery method of mixed plastic

Abstract

The embodiment of the invention provides a recycling method of mixed plastic. The recycling method comprises the following steps that the mixed plastic reacts to obtain a recycled product; the mixed plastic comprises ester plastic and polyvinyl chloride, and the mass ratio of the ester plastic to the polyvinyl chloride is 1: (0.1-10); the reaction temperature is 180-350 DEG C, and the reaction time is 3-52 hours. The mixed plastic is recycled by adopting the steps, the mixed plastic comprising the ester plastic and the PVC is taken as a raw material, during reaction, chlorine (Cl) in the PVC is removed in the form of HCl through thermal dechlorination treatment, the HCl serves as an acid catalyst and / or a depolymerizing agent to participate in the reaction, and the ester plastic is converted into chlorinated derivatives and / or depolymerized into corresponding monomers; and converting the PVC which does not contain the poisoning agent after dechlorination into a corresponding product. Therefore, the mixed plastic comprising the ester plastic and the PVC is recycled, and the ester plastic and the PVC in the mixed plastic are recycled into high-value recycled materials with high benefits.

Description

Technical Field

[0001] The present application relates to the technical field of organic intermediate synthesis, and in particular to a method for recycling mixed plastics. Background Art

[0002] Since its commercialization, plastics have played a vital role in human production and life. Due to the serious environmental problems and resource waste caused by the mass production and waste of plastics and unreasonable end-of-life management schemes, the material recovery of waste plastics by physical / mechanical, chemical or biological methods has attracted widespread attention from academia and industry. For example, polyethylene terephthalate (PET) is one of the most commonly used thermoplastic polymers in the packaging and textile industries. In addition to the simple and easy physical / mechanical method to recover its raw polymer, it can also be depolymerized into polymer monomers and then polymerized into polymers by chemical or biological recovery methods. However, these processes usually require clean, single-component raw materials to ensure good recycled polymer performance and as many recyclable times as possible. However, actual plastic waste is usually a complex mixture containing multiple polymer components as well as plastic additives and other contaminants. For example, PET plastics and polyvinyl chloride (PVC) plastics with similar densities are often difficult to separate completely by simple methods, and due to the different melting points and thermal stabilities of the polymers, contamination from other plastics significantly limits the quality of the recycled materials. In addition, PVC is very likely to produce chlorine-containing inorganic or organic substances during the treatment process, causing problems such as product quality degradation, catalyst poisoning, and reactor corrosion. Although these adverse effects can be eliminated by adding absorbents, it also causes waste of chlorine elements and absorbents in equal stoichiometric ratios. Therefore, designing a high-efficiency recycling system to recycle mixed plastics into high-value chemicals has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0003] The purpose of the embodiment of the present application is to provide a mixed plastic recycling method, which realizes the recycling of mixed plastics and converts the mixed plastics into high-value recycled products. The specific technical solution is as follows:

[0004] The present application provides a method for recycling mixed plastics, comprising the following steps: reacting the mixed plastics to obtain a recycled product; wherein the mixed plastics include ester plastics and polyvinyl chloride (PVC), and the mass ratio of the ester plastics to the polyvinyl chloride is 1:(0.1-10); the reaction temperature is 180-350°C, and the reaction time is 3-52h.

[0005] The above steps provide a new path for the co-conversion of ester plastics and PVC. The path uses a mixed plastic including ester plastics and PVC as a raw material. During the reaction, the chlorine element (Cl) in the PVC is first removed in the form of HCl by thermal dechlorination. HCl participates in the reaction as an acid catalyst and / or depolymerizing agent to convert the ester plastic into a chlorinated derivative and / or depolymerize into the corresponding monomer; then the PVC without the detoxicating agent after dechlorination is converted into the corresponding product. In this way, the recycling of the mixed plastic including ester plastics and PVC is achieved, and the ester plastics and PVC in the mixed plastics are efficiently recycled into high-value recyclables (chemicals). In addition, during the above reaction process, PVC produces HCl to convert and / or depolymerize the ester plastic, which plays the role of an acid catalyst and / or depolymerizing agent, and improves the conversion rate of the ester plastic and the yield of the recovered product. The recycling method of the present application has easy-to-obtain raw materials, a simple process, and can be widely used in industrial production.

[0006] In the present application, the above-mentioned thermal dechlorination treatment is a thermal dechlorination treatment well known in the art. Specifically, the thermal dechlorination treatment refers to the process of removing the chlorine element in PVC in the form of HCl at the reaction temperature during the recycling of mixed plastics.

[0007] In some embodiments of the present application, the reaction is carried out under solvent-free conditions, that is, no solvent (such as ionic liquid or molten salt) is added to the mixed plastic, and the mixed plastic is placed in a sealed container for reaction. The reaction temperature is 250-350°C, and the reaction time is 10-48h. When the mixed plastic is reacted under solvent-free conditions, the temperature and time of the reaction are regulated within the above range, which is conducive to the removal of the chlorine element in the PVC in the form of HCl. In this way, HCl, as an acid catalyst and / or depolymerizing agent, promotes the conversion of ester plastics into chlorinated derivatives and / or depolymerization into corresponding monomers. After dechlorination, PVC also forms PVC without a toxicant (such as HCl) and is then converted into the corresponding product. As a result, it is beneficial to efficiently recover both ester plastics and PVC in the mixed plastics into high-value chemicals.

[0008] In the present application, as shown in reaction formula (1), PVC (weight average molecular weight 10 4 -10 6 ) is placed in a sealed container, and the Cl in the PVC is released in the form of HCl at a temperature of 250-350°C. Specifically, at about 250°C, the Cl in the PVC begins to be released in the form of HCl, and when heated to about 350°C, the Cl in the PVC can be almost completely released, and the released HCl can be used as a depolymerizing agent and acid catalyst for ester plastics. The remaining part of the PVC is converted into dehydrochlorinated polyvinyl chloride (DHPVC), and the mass content of chlorine in the remaining part is less than 3%, and the mass content of oxygen is less than 5%.

[0009]

[0010] In some embodiments of the present application, the reaction is carried out in a reaction medium, the reaction medium is an ionic liquid, and the mass ratio of the ionic liquid to the ester plastic is 1: (0.05-1); the reaction temperature is 180-230°C, and the reaction time is 3-52h. In some embodiments, the reaction time is 6-52h. In some embodiments, the reaction time is 6-12h. When an ionic liquid is selected as a reaction medium, it is beneficial to reduce the reaction temperature, and the recycling process of the mixed plastic does not need to be placed in a sealed container. The ionic liquid can not only serve as a good mass transfer and heat transfer medium for the plastic reaction system, but also as a buffer system for chloride ions. The HCl produced by the thermal dechlorination of PVC is stored in the reaction system for the depolymerization and catalysis of the ester plastic, thereby improving the conversion rate of the ester plastic and the yield of its corresponding chemicals. Regulating the mass ratio of the ionic liquid to the ester plastic within the above range is conducive to the high-efficiency recovery of both the ester plastic and PVC into high-value chemicals. In addition, it is conducive to improving the conversion rate of ester plastics and PVC, as well as the yield of the recovered product.

[0011] In some embodiments of the present application, the ionic liquid is selected from any one of tetrabutylphosphine chloride (Bu4PCl), 1-ethyl-3-methylimidazolium chloride (EmimCl), tetrabutylammonium chloride (Bu4NCl), 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF4). In some embodiments, the ionic liquid is selected from Bu4PCl or EmimCl. In some embodiments, the ionic liquid is selected from Bu4PCl. Taking Bu4PCl as an example, each gram of ionic liquid can absorb about 0.09g of HCl gas and buffer about 0.06g of HCl gas.

[0012] In the present application, after PVC is placed in an ionic liquid and reacted at a temperature of 100-180°C for 0.4-48h, an X-ray fluorescence spectrometer (XRF) is used to measure the Cl content in the PVC, and the residual Cl content in the PVC is 5-50%, indicating that the Cl in the PVC can be removed, and the removal amount is high. In some embodiments, 2-5g PVC is placed in 29-31g ionic liquid Bu4PCl, and after reacting at a temperature of 100-180°C for 0.5-48h, the Cl content in the PVC is measured by XRF, and the residual Cl content in the PVC is 5.5-15.2%. In some embodiments, 2-4g PVC is placed in 29-31g ionic liquid EmimCl, and after reacting at a temperature of 100-180°C for 0.4-0.6h, the Cl content in the PVC is measured by XRF, and the residual Cl content in the PVC is 37.6-48.2%.

[0013] In some embodiments of the present application, the reaction is carried out in a reaction medium, the reaction medium is a molten salt, and the mass ratio of the molten salt to the ester plastic is 1: (0.01-0.2); the reaction temperature is 200-350°C, and the reaction time is 10-24h. When the molten salt is used as the reaction medium, it is beneficial to the removal of HCl from PVC and the activation and conversion of HCl. Regulating the mass ratio of the molten salt to the ester plastic within the above range is beneficial to the efficient recovery of both the ester plastic and PVC into high-value chemicals. In addition, it is beneficial to improve the conversion rate of ester plastics and PVC, as well as the yield of the recovered product.

[0014] In some embodiments of the present application, the molten salt is selected from any one of a NaCl-KCl-ZnCl mixture and a NaCl-KCl-MgCl mixture. Further, the mass ratio of NaCl, KCl and ZnCl in the NaCl-KCl-ZnCl mixture is 1:(0.8-1.5):(2-4), and the mass ratio of NaCl, KCl and MgCl in the NaCl-KCl-MgCl mixture is 1:(0.8-1.5):(2-4). It should be noted that the NaCl-KCl-ZnCl mixture is obtained by directly mixing NaCl, KCl and ZnCl, and the NaCl-KCl-MgCl mixture is obtained by directly mixing NaCl, KCl and MgCl.

[0015] In some embodiments of the present application, a catalyst may be added during the reaction, and the mass ratio of the catalyst to the ester plastic is 1:(2-56); the catalyst is an acid catalyst, and the acid catalyst includes any one of a Lewis acid catalyst, a protonic acid catalyst, and a solid acid catalyst; the Lewis acid is selected from any one of ZnCl2, FeCl3, AlCl3, and Sc(OTf)3; the protonic acid catalyst is selected from H2SO4; the solid acid catalyst is selected from H-ZSM-5 molecular sieve. In some embodiments, the catalyst is ZnCl2. In some embodiments, the catalyst is FeCl3. In some embodiments, the catalyst is H2SO4. The addition of the above-mentioned types and contents of catalysts is conducive to improving the conversion rate of PVC and ester plastics, as well as the yield of the recovered product.

[0016] In some embodiments of the present application, the size of the ester plastic is 0.1-3 mm. By regulating the size of the ester plastic within the above range, the ester plastic has a smaller size, which is conducive to making the depolymerization and / or conversion of the ester plastic more complete, thereby accelerating the generation rate of the recycled product on the basis of converting the ester plastic into its corresponding chemical.

[0017] The present application has no particular limitation on the size of PVC, as long as the purpose of the present application can be achieved. For example, the size of PVC is 0.1-3 mm, which is conducive to the removal of chlorine during thermal dechlorination treatment and is conducive to accelerating the generation rate of the recovered product.

[0018] In the present application, size refers to average particle size, and further, average particle size refers to the average diameter of mixed plastic particles or powders.

[0019] In some embodiments of the present application, the ester plastic includes an ester polymer, and the ester polymer is selected from at least one of polyethylene terephthalate (PET), polybutylene terephthalate, polylactic acid, polycaprolactone, polyglycolic acid, polyhydroxyalkanoates, polybutylene succinate, polybutylene adipate, polyhexane adipate, polycarbonate, and polyurethane; the polyhydroxyalkanoate is selected from at least one of poly-β-hydroxybutyric acid, polyhydroxyvalerate, polyhydroxycaproate, and polyhydroxyoctanoate.

[0020] In some embodiments of the present application, the ester plastic further includes an ester additive, and the ester additive includes a phthalic acid diester. The present application has no particular restrictions on the type of the phthalic acid diester, as long as the purpose of the present application can be achieved. For example, the phthalic acid diester includes dibutyl phthalate, diisobutyl phthalate, benzyl butyl phthalate, di(2-ethylhexyl) phthalate, etc.

[0021] In the present application, the recycled product refers to the chemicals corresponding to the ester plastics and the chemicals corresponding to PVC obtained by converting and / or depolymerizing the mixed plastics using the recycling method of the present application.

[0022] In some embodiments of the present application, the recovered product is selected from at least one of terephthalic acid (TPA), ethylene dichloride (EDC), dichlorobutane, dichloroethanol terephthalate, phthalic acid, dichlorobutyl phthalate, hydrogen chloride (HCl), and dehydrochlorinated polyvinyl chloride (DHPVC).

[0023] In the present application, conversion rate refers to the percentage of conversion of mixed plastics (ester plastics and PVC), wherein ester plastic conversion rate = ester plastics that have undergone depolymerization reaction / feed amount of ester plastics × 100%, PVC conversion rate = PVC that has undergone dehydrochlorination reaction / feed amount of PVC × 100%. Yield refers to the percentage of various recovered products produced by the mixed plastics through the recovery method of the present application, calculated based on the feed amount of a certain reactant. As an example, when the ester plastic is PET, TPA yield = TPA generated by depolymerization reaction / total amount of TPA monomers contained in the PET fed × 100%, terephthalic acid dichloroethanol yield = terephthalic acid dichloroethanol generated by depolymerization reaction / total amount of TPA monomers contained in the PET fed × 100%, EDC yield = EDC generated by depolymerization reaction / total amount of ethylene glycol monomers contained in the PET fed × 100%.

[0024] Beneficial effects of the embodiments of the present application:

[0025] The embodiment of the present application provides a method for recycling mixed plastics, comprising the following steps: reacting the mixed plastics to obtain a recycled product; the mixed plastics include ester plastics and polyvinyl chloride, and the mass ratio of ester plastics to polyvinyl chloride is 1: (0.1-10); the reaction temperature is 180-350°C, and the reaction time is 3-52h. The above steps are used to recycle the mixed plastics, and the mixed plastics including ester plastics and PVC are used as raw materials. During the reaction, the chlorine element (Cl) in the PVC is first removed in the form of HCl by thermal dechlorination treatment, and HCl participates in the reaction as an acid catalyst and / or depolymerizer to convert the ester plastics into chlorinated derivatives and / or depolymerize into corresponding monomers; and then the PVC without detoxifying agents after dechlorination is converted into corresponding products. In this way, the recycling of mixed plastics including ester plastics and PVC is achieved, and the ester plastics and PVC in the mixed plastics are both efficiently recycled into high-value recyclables (chemicals). In addition, during the above reaction process, PVC produces HCl to convert and / or depolymerize the ester plastic, playing the role of an acid catalyst and / or depolymerizing agent, thereby increasing the conversion rate of the ester plastic and the yield of the recovered product. The recovery method of the present application has readily available raw materials and a simple process, and can be widely used in industrial production.

[0026] Of course, implementing any product or method of the present application does not necessarily require achieving all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0028] Figure 1 The gas chromatography-mass spectrometry (GC-MS) chromatogram of the product recovered in Example 1;

[0029] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of the terephthalic acid recovered in Example 1;

[0030] Figure 3 It is a comparison chart of the generation rate of the recovered product EDC in Example 4, Example 6 and Example 13. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field based on the present application belong to the scope of protection of the present application.

[0032] The following examples and comparative examples are given to more specifically illustrate the embodiments of the present application. Various tests and evaluations are performed according to the following methods. It should be noted that in the following examples and comparative examples, PVC is polymerized from the monomer vinyl chloride, and PET is polymerized from the two monomers terephthalic acid and ethylene glycol.

[0033] Test methods and equipment

[0034] The reaction systems of the embodiments and comparative examples were qualitatively and quantitatively analyzed by GC-MS, gas chromatograph and nuclear magnetic resonance spectrometer.

[0035] Example 1

[0036]

[0037] A solvent-free reaction system was selected, and 100 mg PET (0.52 mmol TPA monomer and 0.52 mmol ethylene glycol monomer, with a weight average molecular weight of 10 4 -10 6 ) and 150 mg PVC (0.79 mmol vinyl chloride monomer, weight average molecular weight 10 4 -10 6), react at 300°C for 5h to obtain a recovered product (as shown in reaction formula (2)). After the reaction, there is a pungent smell of HCl in the tube. The recovered product is dissolved in 2.0g of dimethylformamide (DMF), and the generated amount of each recovered product is about 0.04mmol TPA, 0.05mmol EDC and 0.17mmol terephthalic acid dichloroethanol ester through GC-MS and gas chromatography analysis.

[0038] Among them, the size of PET is 3.0mm and the size of PVC is 0.1mm.

[0039] Example 2

[0040]

[0041] In the reaction system of 6g ionic liquid Bu4PCl, 300mg PET (1.56mmol TPA monomer and 1.56mmol ethylene glycol monomer, weight average molecular weight 10 4 -10 6 ) and 500 mg PVC (2.63 mmol vinyl chloride monomer, weight average molecular weight of 10 4 -10 6 ), react at 180°C for 3h to obtain a recovered product (as shown in reaction formula (3)). The recovered product was dissolved in 2.0g DMF, and analyzed by GC-MS and gas chromatography to obtain the production amount of each recovered product of about 0.02mmol TPA and 0.02mmol EDC.

[0042] Among them, the size of PET is 3.0mm and the size of PVC is 0.1mm.

[0043] Example 3

[0044] Except that the reaction time was adjusted to 12 h, the rest was the same as Example 2.

[0045] Example 4

[0046] The process was the same as Example 2 except that the reaction temperature was adjusted to 230° C. and the reaction time was adjusted to 6 h.

[0047] Example 5

[0048]

[0049] In a 5g molten salt NaCl-KCl-ZnCl2 mixture (the mass ratio of NaCl, KCl and ZnCl2 is 1:1:3) reaction system, 300mg PET (1.56mmol TPA monomer and 1.56mmol ethylene glycol monomer, weight average molecular weight 10 4 -106 ) and 500 mg PVC (2.63 mmol vinyl chloride monomer, weight average molecular weight of 10 4 -10 6 ), react at 230° C. for 12 h to obtain a recovered product (as shown in reaction formula (3)). The recovered product was dissolved in 2.0 g of DMF, and analyzed by GC-MS and gas chromatography to obtain the production amounts of various recovered products of 0.02 mmol TPA and 0.02 mmol EDC.

[0050] Among them, the size of PET is 3.0mm and the size of PVC is 0.1mm.

[0051] Example 6

[0052]

[0053] In the reaction system of 6g ionic liquid Bu4PCl, 300mg PET (1.56mmol TPA monomer and 1.56mmol ethylene glycol monomer, weight average molecular weight 10 4 -10 6 ), 500mg PVC (2.63mmol vinyl chloride monomer, weight average molecular weight is 10 4 -10 6 ) and 100 mg of catalyst ZnCl2, react at 230°C for 6 h to obtain a recovered product (as shown in reaction formula (4)). The recovered product was dissolved in 2 g of DMF, and analyzed by GC-MS and gas chromatography to obtain the production amount of each recovered product of about 1.2 mmol TPA and 1.28 mmol EDC.

[0054] Among them, the size of PET is 3.0mm and the size of PVC is 0.1mm.

[0055] Example 7

[0056]

[0057] Except that ZnCl2 is adjusted to FeCl3, the rest is the same as Example 6. The reaction process is shown in reaction formula (5).

[0058] Example 8

[0059]

[0060] Except that ZnCl2 is adjusted to H2SO4, the rest is the same as Example 6. The reaction process is shown in reaction formula (6).

[0061] Example 9

[0062]

[0063] Except that ZnCl2 is adjusted to Sc(OTf)3, the rest is the same as Example 6. The reaction process is shown in reaction formula (7).

[0064] Example 10

[0065]

[0066] Except that ZnCl2 is adjusted to H-ZSM-5 molecular sieve, the rest is the same as Example 6. The reaction process is shown in reaction formula (8).

[0067] Embodiment 11

[0068]

[0069] In the reaction system of 5g ionic liquid Bu4PCl, 5.6g PET (29.12mmol TPA monomer and 29.12mmol ethylene glycol monomer, weight average molecular weight 10 4 -10 6 ), 3.5 g PVC (18.41 mmol vinyl chloride monomer, weight average molecular weight is 10 4 -10 6 ) and 100 mg of catalyst ZnCl2, react at 230°C for 52 h to obtain a recovered product (as shown in reaction formula (3)). The recovered product was dissolved in 2 g of DMF, and analyzed by GC-MS and gas chromatography to obtain the production amounts of various recovered products of 28.54 mmol TPA and 27.55 mmol EDC.

[0070] Among them, the size of PET is 3.0mm and the size of PVC is 0.1mm.

[0071] Example 12

[0072]

[0073] In the reaction system of 5g ionic liquid Bu4PCl, 300mg PET (1.56mmol TPA monomer and 1.56mmol ethylene glycol monomer, weight average molecular weight of 10 4 -10 6 ), 3.0 g PVC (15.6 mmol vinyl chloride monomer, weight average molecular weight 10 4 -10 6) and 100 mg of catalyst ZnCl2, react at 230°C for 6 h to obtain a recovered product (as shown in reaction formula (3)). The recovered product was dissolved in 2 g of DMF, and analyzed by GC-MS and gas chromatography to obtain the production amount of each recovered product of about 1.52 mmol TPA and 1.48 mmol EDC.

[0074] Among them, the size of PET is 3.0mm and the size of PVC is 0.1mm.

[0075] Example 13

[0076] Except for adjusting the size of PET to 0.1 mm, the rest is the same as Example 6.

[0077] Comparative Example 1 to Comparative Example 3

[0078] Except for adjusting the relevant reaction parameters according to Table 1, the rest is the same as Example 2.

[0079] The test results of Examples 1-13 and Comparative Examples 1-3 are shown in Tables 1 and Figure 3 shown.

[0080] Table 1

[0081]

[0082]

[0083] Note: “\” in Table 1 indicates no corresponding parameter; the difference between Example 6 and Example 13 is that the size of PET in Example 6 is 3.0 mm, and the size of PET in Example 13 is 0.1 mm;.

[0084] It can be seen from Examples 1-13 and Comparative Examples 1-3 that when the mass ratio of ester plastics to PVC in the mixed plastics is within the range of this application, and the temperature and time of the reaction are within the range of this application, the mixed plastics can be converted into high-value recycled products after the reaction. In the comparative examples, however, the mass ratio of ester plastics to PVC is not within the range of this application, or the temperature and time of the reaction are not within the range of this application, and the mixed plastics cannot be converted into recycled products.

[0085] Figure 1 The GC-MS chromatogram of the recovered products in Example 1 is shown. It can be seen from the figure that the recovered products after the mixed plastic conversion in Example 1 include EDC and dichloroethylene terephthalate. Figure 2 The hydrogen nuclear magnetic resonance spectrum of the terephthalic acid recovered in Example 1 is shown.

[0086] It can be seen from Examples 1-5 that under solvent-free conditions and when the reaction medium is an ionic liquid or a molten salt, mixed plastics can be converted into high-value recycled products under the conversion path of the present application.

[0087] It can be seen from Examples 4 and 6-13 that adding the catalyst of the present application during the reaction of the mixed plastics can further improve the conversion rate of PVC and ester plastics, as well as the yield of the recovered products.

[0088] Figure 3 The comparison of the EDC generation rate of the recovered product in Example 4, Example 6 and Example 13 is shown. Specifically, Example 13 is curve (a), which indicates that the PET particle size is 0.1 mm and the catalyst ZnCl2 is used; Example 6 is curve (b), which indicates that the PET particle size is 3.0 mm and the catalyst ZnCl2 is used; Example 4 is curve (c), which indicates that the PET particle size is 3.0 mm and no catalyst is used. From the data in Table 1 and Figure 3 It can be seen that the use of catalyst and the reduction of PET particle size can accelerate the generation rate of EDC.

[0089] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method or article that includes a series of elements includes not only those elements, but also includes other elements that are not explicitly listed, or also includes elements that are inherent to such process, method or article.

[0090] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0091] The above description is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A method for recycling mixed plastics, comprising the following steps: reacting the mixed plastics to obtain a recycled product; The mixed plastic includes ester plastic and polyvinyl chloride, and the mass ratio of the ester plastic to the polyvinyl chloride is 1:(0.1-10); The reaction temperature is 180-350° C., and the reaction time is 3-52 h.

2. The method according to claim 1, wherein: The reaction is carried out in the absence of a solvent, the reaction temperature is 250-350° C., and the reaction time is 10-48 hours.

3. The method according to claim 1, wherein: The reaction is carried out in a reaction medium, the reaction medium is an ionic liquid, and the mass ratio of the ionic liquid to the ester plastic is 1:(0.05-1); The reaction temperature is 180-230° C., and the reaction time is 3-52 h.

4. The method according to claim 3, wherein: The ionic liquid is selected from any one of tetrabutylphosphine chloride, 1-ethyl-3-methylimidazolium chloride, tetrabutylammonium chloride, and 1-ethyl-3-methylimidazolium tetrafluoroborate.

5. The method according to claim 1, wherein: The reaction is carried out in a reaction medium, the reaction medium is a molten salt, and the mass ratio of the molten salt to the ester plastic is 1:(0.01-0.2); The reaction temperature is 200-350° C., and the reaction time is 10-24 hours.

6. The method according to claim 5, wherein: The molten salt is selected from any one of a NaCl-KCl-ZnCl2 mixture and a NaCl-KCl-MgCl2 mixture.

7. The method according to claim 1, wherein: A catalyst may also be added during the reaction, and the mass ratio of the catalyst to the ester plastic is 1:(2-56); The catalyst is an acid catalyst, which includes any one of a Lewis acid catalyst, a protonic acid catalyst, and a solid acid catalyst; the Lewis acid is selected from any one of ZnCl2, FeCl3, AlCl3, and Sc(OTf)3; the protonic acid catalyst is selected from H2SO4; and the solid acid catalyst is selected from H-ZSM-5 molecular sieve.

8. The method according to claim 1, wherein: The size of the ester plastic is 0.1-3 mm.

9. The method according to claim 1, wherein: The ester plastic comprises an ester polymer, and the ester polymer is selected from at least one of polyethylene terephthalate, polybutylene terephthalate, polylactic acid, polycaprolactone, polyglycolic acid, polyhydroxyalkanoate, polybutylene succinate, polybutylene adipate, polyhexane adipate, polycarbonate, and polyurethane; The polyhydroxyalkanoate is selected from at least one of poly-β-hydroxybutyric acid, polyhydroxyvalerate, polyhydroxycaproate and polyhydroxyoctanoate.

10. The method according to claim 9, wherein: The ester plastic further comprises an ester additive, and the ester additive comprises phthalic acid diester.

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