A technology for preparing recycled resin based on waste polyester alcoholysis byproducts

Abstract

The present invention provides a regenerated resin preparation technology based on waste polyester alcoholysis byproducts, comprising the following steps: S1) mixing a divalent metal salt, a trivalent metal salt and an alkaline reagent, freeze-drying after hydrothermal reaction to obtain a layered double metal hydroxide; S2) mixing porous boron nitride, layered double metal hydroxide, crown ether and water, freeze-drying after deposition to obtain a self-assembled solid material, and then ball milling to obtain a hybrid material; S3) esterifying the oligomer byproducts of waste polyester alcoholysis, carboxylic acid organic matter and the hybrid material, and then performing a polymerization reaction to obtain a regenerated resin. The present application also provides a method for preparing the hybrid material. The present application provides a regenerated resin preparation technology, which effectively inhibits the degradation and end-capping effect of potassium ions on the molecular chain polycondensation reaction by introducing a hybrid material, and exhibits excellent polymerization catalytic performance, providing a new way for the high-value utilization of waste polyester alcoholysis byproducts.

Description

Technical Field

[0001] The invention relates to the technical field of waste polyester regeneration, in particular to a technology for preparing regenerated resin based on alcoholysis byproducts of waste polyester. Background Art

[0002] Polyethylene terephthalate (PET), as a thermoplastic polyester material, has been widely used in many fields such as fibers, plastics and films due to its excellent heat resistance, mechanical properties, chemical stability, electrical insulation and wear resistance. The use of chemical recycling technology to depolymerize waste PET into small molecular monomers and prepare high-performance recycled products through subsequent polymerization processes has important economic and practical significance for the recycling of waste PET. Among many chemical recycling methods, ethylene glycol alcoholysis can effectively depolymerize waste PET into dihydroxyethyl terephthalate (BHET). The reaction conditions are mild, the safety is good and the product yield is high, making it one of the key technologies for recycling waste PET.

[0003] However, in the alcoholysis of waste polyester glycol, the PET molecular chain breakage position is random, the depolymerization reaction is often incomplete, and the product BHET is prone to etherification reaction at high temperature, resulting in the production of a series of low-polymerization byproducts in addition to BHET. In addition, potassium carbonate, as an economical, environmentally friendly, low-toxic and efficient catalyst, has been widely used in the alcoholysis of waste polyester, but due to its easy solubility in alcohol depolymerization liquid, it will remain in the depolymerization byproducts in small amounts. When these depolymerization byproducts are used as raw materials to prepare recycled resins, the potassium ions released by the residual potassium carbonate as Lewis acid will seriously inhibit the molecular chain viscosity increase reaction. At the same time, potassium ions will also react with the ester groups on the resin molecular chain to induce molecular chain degradation, seriously affecting the stability of the polymerization reaction and the increase of polymer viscosity, making it difficult for a large number of depolymerization byproducts to be recycled. Although attempts have been made to shield potassium ions by adding metal chelators such as crown ethers online, the effect is not ideal, and such metal chelators will block the active centers of the polymerization catalyst during the reaction, further reducing the polymerization efficiency. Therefore, there is an urgent need to provide a method for preparing a new type of regenerated resin to achieve efficient and selective removal of potassium ions without inhibiting the polycondensation and viscosity-increasing reaction process. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a regenerated resin preparation technology based on waste polyester alcoholysis by-products. The regenerated resin preparation technology provided by the present application can effectively remove potassium ions in waste polyester alcoholysis by-products and make the prepared regenerated resin have better performance.

[0005] In view of this, the present application provides a technology for preparing recycled resin based on waste polyester alcoholysis byproducts, comprising the following steps:

[0006] S1) mixing a divalent metal salt, a trivalent metal salt and an alkaline reagent, performing a hydrothermal reaction and then freeze-drying to obtain a layered double metal hydroxide;

[0007] S2) mixing porous boron nitride, layered double metal hydroxide, crown ether and water, freeze-drying after deposition to obtain a self-assembled solid material, and ball-milling the self-assembled solid material to obtain a porous boron nitride@double metal hydroxide-crown ether hybrid material;

[0008] S3) subjecting the oligomer byproduct of alcoholysis of waste polyester, carboxylic acid organic matter and the hybrid material to an esterification reaction, and then to a polymerization reaction to obtain a recycled resin.

[0009] Preferably, the preparation method of the porous boron nitride is specifically as follows:

[0010] A boron source, a nitrogen source, a pore former and water are mixed and heated to obtain a boron nitride precursor;

[0011] The boron nitride precursor is calcined to obtain porous boron nitride.

[0012] Preferably, the boron source includes one or more of boric acid, ammonia borane, metaboric acid, boron chloride, boron oxide, boron sulfide and sodium borohydride; the nitrogen source includes one or more of urea, melamine, sodium azide, dicyandiamide and sodium amide; the pore former includes one or more of zinc acetate, nickel sulfate, cobalt sulfate, iron sulfate, copper sulfate and zinc sulfate;

[0013] And / or, the mass ratio of the boron source to the nitrogen source is 10:(3-8);

[0014] And / or, the calcination temperature is 500-1500° C., the time is 3-10 hours, and the calcination is carried out under a protective atmosphere, and the protective atmosphere is nitrogen or argon.

[0015] Preferably, in step S1), the divalent metal cations in the divalent metal salt include Fe 2+ 、Ni 2+ , Cu 2+ 、Zn 2+ and Mg 2+ One or more of; and / or, the trivalent metal cation in the trivalent metal salt includes Ni 3+ , Fe 3+ 、Al 3 + and Ti 3+ One or more of; and / or, the anions in the divalent metal salt and the trivalent metal salt are independently selected from SO 4 2- 、NO 3-, CO 3 2- and Cl - One or more of; and / or, the alkaline agent includes one of urea, ammonia water and sodium hydroxide.

[0016] Preferably, in step S1), the mass ratio of the divalent metal salt to the trivalent metal salt is (1-5):1, so the ratio of the total mass of the divalent metal salt and the trivalent metal salt to the mass of the alkaline reagent is 1:(0.5-5); and / or, the temperature of the hydrothermal reaction is 50-100°C, and the time is 10-25h; and / or, the freeze-drying time is 10-15h.

[0017] Preferably, in step S2), the crown ether includes one or more of 18-crown-6, dibenzo-18-crown-6, dibenzo-30-crown-10, 15-crown-5 and cyclohexanedo-18-crown-6;

[0018] And / or, the mass ratio of the porous boron nitride, the layered double hydroxide and the crown ether is 10:(5-10):(3-8).

[0019] Preferably, in step S2), the deposition temperature is 20-80°C and the deposition time is 3-15h;

[0020] And / or, the deposition further includes ultrasonic dispersion, and the ultrasonic dispersion time is 20 to 60 minutes;

[0021] And / or, the freeze-drying time is 20 to 40 hours;

[0022] And / or, the masses of the grinding beads of the ball mill are 2.5 g, 10 g, 14 g, 15 g, and 55 g, respectively, with the corresponding quantity ratio being (14-16): (9-11): (4-6): (4-6): (2-4), the ball milling time is 10-30 h, and the rotation speed is 300-500 r / min.

[0023] Preferably, in step S3), the waste polyester includes one or more of waste polyester fibers, waste polyester plastics and waste polyester films;

[0024] and / or, the carboxylic acid organic compound comprises one or more of terephthalic acid, adipic acid, isophthalic acid, 4-bromophthalic acid, phthalic anhydride, p-hydroxybenzoic acid and succinic acid;

[0025] And / or, the mass ratio of the oligomer by-product, the carboxylic acid organic matter and the hybrid material is 600: (120-250): (10-20).

[0026] Preferably, the temperature of the esterification reaction is 100-250° C., and the time is 2-5 h; the vacuum degree of the polymerization reaction is 40-100 Pa, the temperature is 200-300° C., and the time is 3-6 h.

[0027] The present application also provides a method for preparing a hybrid material, comprising the following steps:

[0028] S1) mixing a divalent metal salt, a trivalent metal salt and an alkaline reagent, performing a hydrothermal reaction and then freeze-drying to obtain a layered double metal hydroxide;

[0029] S2) mixing porous boron nitride, layered double metal hydroxide, crown ether and water, freeze-drying after deposition to obtain a self-assembled solid material, and ball-milling the self-assembled solid material to obtain a porous boron nitride@double metal hydroxide-crown ether hybrid material.

[0030] The present application provides a technology for preparing a recycled resin based on waste polyester alcoholysis byproducts, which firstly mixes a divalent metal salt, a trivalent metal salt and an alkaline reagent, performs a hydrothermal reaction and then freeze-dries to obtain a layered double metal hydroxide, then deposits porous boron nitride, the layered double metal hydroxide and a crown ether to obtain a self-assembled solid material, then ball-mills the self-assembled solid material to obtain a porous boron nitride@double metal hydroxide-crown ether hybrid material, and finally esterifies the oligomer byproducts of the alcoholysis of the waste polyester, carboxylic acid organic matter and the hybrid material and then polymerizes them to obtain a recycled resin; in the process of utilizing the waste polyester In the process of preparing recycled resin from ester alcoholysis by-products, porous boron nitride@double hydroxide-crown ether hybrid material was introduced. It successfully combined the strong metal ion adsorption of porous boron nitride and layered double hydroxide, the catalytic properties of layered double hydroxide and the selective ion complexation of crown ether, forming a highly efficient adsorption and shielding of potassium ions in waste polyester alcoholysis by-products, which can effectively eliminate the molecular chain capping effect that may be caused by potassium carbonate in the initial stage of esterification, and avoid the occurrence of nucleophilic-electrophilic and other side reactions in the subsequent condensation stage, thereby improving the overall polymerization reaction efficiency and the quality of recycled resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a SEM image of the powdered self-assembled porous BN@Fe / Ti-LDHs@18-crown-6 hybrid material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0033] In view of the problem of potassium ion residues in waste polyester alcoholysis byproducts in the prior art and the need for the preparation of regenerated resins, the present application provides a method for preparing a self-assembled porous boron nitride@layered double metal hydroxide-crown ether hybrid material, and at the same time provides a regenerated resin preparation technology based on waste polyester alcoholysis byproducts. The hybrid material integrates the metal ion efficient adsorption performance of porous boron nitride (BN) and layered double metal hydroxides (LDHs) and the catalytic advantages of LDHs, and the introduction of crown ethers can accurately capture and chelate and shield potassium ions, avoiding their negative impact on the polymerization reaction during the preparation of regenerated resins. At the same time, as an efficient polymerization reaction catalyst, the material can effectively improve the recovery rate of depolymerization byproducts and has important application value. Specifically, the present application first provides a regenerated resin preparation technology based on waste polyester alcoholysis byproducts, including the following steps:

[0034] S1) mixing a divalent metal salt, a trivalent metal salt and an alkaline reagent, performing a hydrothermal reaction and then freeze-drying to obtain a layered double metal hydroxide;

[0035] S2) mixing porous boron nitride, layered double metal hydroxide, crown ether and water, freeze-drying after deposition to obtain a self-assembled solid material, and ball-milling the self-assembled solid material to obtain a porous boron nitride@double metal hydroxide-crown ether hybrid material;

[0036] S3) subjecting the oligomer byproduct of alcoholysis of waste polyester, carboxylic acid organic matter and the hybrid material to an esterification reaction, and then to a polymerization reaction to obtain a recycled resin.

[0037] In the process of preparing the regenerative resin, the present application first prepares a layered double hydroxide (LDHs), that is, a divalent metal salt, a trivalent metal salt and an alkaline reagent are mixed, and freeze-dried after a hydrothermal reaction to obtain a layered double hydroxide (LDHs); in this process, the metal cations in the divalent metal salt include Fe 2+ 、Ni 2+ , Cu 2+ 、Zn 2+ and Mg 2+ Specifically, the metal cation in the divalent metal salt is selected from Fe 2+ 、Ni 2+ , Cu 2+ 、Zn 2+ and Mg 2+ More specifically, the metal cation in the divalent metal salt is selected from Fe 2+ ,Mg 2+ , Cu 2+ , Zn 2+ , Ni 2+ , Cu 2+ and Fe2+ The combination of Ni 2+ and Zn 2+ Combination or Ni 2+ and Fe 2+ The metal cation in the trivalent metal salt includes Ni 3 + , Fe 3+ 、Al 3+ and Ti 3+ Specifically, the metal salt ion in the trivalent metal salt is selected from Ni 3+ , Fe 3+ 、Al 3+ and Ti 3+ The anions of the divalent metal salt and the trivalent metal salt are independently selected from SO 4 2- 、NO 3 - , CO 3 2- and Cl - Specifically, the anions of the divalent metal salt and the trivalent metal salt are independently selected from SO 4 2- and Cl - One or two of the above. The alkaline reagent includes one of urea, ammonia water and sodium hydroxide. Specifically, the alkaline reagent is selected from urea or sodium hydroxide. The mass ratio of the divalent metal salt to the trivalent metal salt is (1-5):1. Specifically, the mass ratio of the divalent metal salt to the trivalent metal salt is (1.25-3):1. Specifically, the mass ratio of the divalent metal salt to the trivalent metal salt is (1.3-2.3):1. In a specific embodiment, the mass ratio of the divalent metal salt to the trivalent metal salt is 1:1, 1.125:1, 1.25:1, 1.4:1, 1.5:1 or 1.68:1. The ratio of the total mass of the divalent metal salt and the trivalent metal salt to the mass of the alkaline reagent is 1: (0.5-5), specifically, the ratio of the total mass of the divalent metal salt and the trivalent metal salt to the mass of the alkaline reagent is 1: (0.8-3), specifically, the ratio of the total mass of the divalent metal salt and the trivalent metal salt to the mass of the alkaline reagent is 1: (0.9-2.3); in a specific embodiment, the ratio of the total mass of the divalent metal salt and the trivalent metal salt to the mass of the alkaline reagent is 1: 125, 1: 1.18 or 1: 1.19. The temperature of the reaction is 50-100 ° C, and the time is 10-25h; specifically, the temperature of the reaction is 60-95 ° C, and the time is 12-20h. The freeze-drying time is 10-15h. The present application synthesizes layered LDHs using a hydrothermal method combined with a freeze-drying process.

[0038] The preparation of the layered double metal hydroxide is more specifically as follows:

[0039] The divalent metal salt, trivalent metal salt and alkaline reagent are dissolved in water in a certain proportion, then transferred to a hydrothermal kettle, placed in an oven for crystallization, cooled after the crystallization, and then centrifuged and washed multiple times to remove impurities, and finally freeze-dried to obtain a layered double hydroxide (LDH).

[0040] The present application then mixes porous boron nitride, layered double metal hydroxide, crown ether and water, freeze-dries after deposition, and obtains a self-assembled solid material; in this process, the porous boron nitride is preferably porous boron nitride micropowder, and specifically, the preparation method of the porous boron nitride micropowder is as follows:

[0041] A boron source, a nitrogen source, a pore former and water are mixed and heated to obtain a boron nitride precursor;

[0042] The boron nitride precursor is calcined to obtain porous boron nitride.

[0043] In the preparation process of the porous boron nitride, the boron source includes one or more of boric acid, ammonia borane, metaboric acid, boron chloride, boron oxide, boron sulfide and sodium borohydride. Specifically, the boron source is selected from one of boric acid, ammonia borane, metaboric acid, boron chloride, boron oxide, boron sulfide and sodium borohydride. The nitrogen source includes one or more of urea, melamine, sodium azide, dicyandiamide and sodium amide. Specifically, the nitrogen source is selected from one of urea, melamine, sodium azide, dicyandiamide and sodium amide. More specifically, the nitrogen source is selected from urea, melamine, dicyandiamide or sodium azide. The pore-forming agent includes one or more of zinc acetate, nickel sulfate, cobalt sulfate, iron sulfate, copper sulfate and zinc sulfate. Specifically, the pore-forming agent is selected from one of zinc acetate, nickel sulfate, cobalt sulfate, iron sulfate, copper sulfate and zinc sulfate. More specifically, the pore-forming agent is selected from zinc acetate, copper sulfate or iron sulfate. The mass ratio of the boron source to the nitrogen source is 10: (3-8), specifically, the mass ratio of the boron source to the nitrogen source is (1.125-2.00): 1, more specifically, the mass ratio of the boron source to the nitrogen source is (1.25-1.80): 1, more specifically, the mass ratio of the boron source to the nitrogen source is (1.35-1.70): 1, more specifically, the mass ratio of the boron source to the nitrogen source is (1.37-1.60): 1. The mass ratio of the nitrogen source to the pore-forming agent is (15-21): 1, specifically, the mass ratio of the nitrogen source to the pore-forming agent is (18-20): 1. The heating temperature is 80-120° C., specifically, the heating temperature is 95-110° C. The heating is performed to evaporate the water to obtain a white boron nitride (BN) precursor.

[0044] Then the BN precursor is ground and calcined to obtain porous BN powder. In this process, the grinding is a grinding method well known to those skilled in the art and is not particularly limited here; the calcination temperature is 500-1500°C and the time is 3-10 hours; the calcination is carried out under a protective atmosphere, and the protective atmosphere includes one of nitrogen and argon; specifically, the calcination temperature is 700-900°C and the time is 3.5-6 hours, more specifically, the calcination temperature is 750-850°C and the time is 4-5 hours. The present application prepares porous BN powder by combining a pore-forming agent with a calcination process.

[0045] According to the present invention, porous boron nitride, layered double metal hydroxide, crown ether and water are then mixed, deposited and freeze-dried to obtain a self-assembled solid material, and the self-assembled solid material is ball-milled to obtain a porous boron nitride@double metal hydroxide-crown ether hybrid material; in this process, the crown ether includes one or more of 18-crown-6, dibenzo-18-crown-6, dibenzo-30-crown-10, 15-crown-5 and cyclohexane-18-crown-6, specifically, the crown ether is selected from one of 18-crown-6, dibenzo-18-crown-6, dibenzo-30-crown-10, 15-crown-5 and cyclohexane-18-crown-6, more specifically, the The crown ether is selected from one of 18-crown-6, dibenzo-18-crown-6, N,N,N',N'-tetramethyl-4,4'-diaminodiphenyl-18-crown-6, 15-crown-5 and cyclohexaned-18-crown-6; the mass ratio of the porous boron nitride, the layered double metal hydroxide and the crown ether is 10:(5-10):(3-8), specifically, the mass ratio of the porous boron nitride, the layered double metal hydroxide and the crown ether is 10:(6-8):(4-7); in a specific embodiment, the mass ratio of the porous boron nitride, the layered double metal hydroxide and the crown ether is 10:8:6 or 10:8:5. The deposition temperature is 20-80°C and the time is 3-15h. Specifically, the deposition temperature is 30-40°C and the time is 4-12h. The freeze drying step further includes ultrasonic dispersion, the ultrasonic dispersion time is 20 to 60 minutes, specifically, the ultrasonic dispersion time is 35 to 45 minutes. The freeze drying step is 20 to 40 hours, specifically, the freeze drying step is 25 to 30 hours.

[0046] The present application then ball-mills the self-assembled solid material to obtain a porous boron nitride@double metal hydroxide-crown ether hybrid material; the mass ratio of the ball milling beads is 2.5:10:14:15:55, and the corresponding number ratio is (14-16): (9-11): (4-6): (4-6): (2-4), specifically, the corresponding number ratio is 15:10:5:5:3; the ball milling time is 10-30 hours, and the rotation speed is 300-500 r / min, specifically, the ball milling time is 15-25 hours, and the rotation speed is 350-400 r / min. During this process, the crown ether was uniformly adsorbed and deposited on the surface of the porous BN and LDHs mixture through ultrasonic dispersion to ensure that the initial deposition of the crown ether was fully mixed with the components. Its structure was stabilized by freeze-drying. Finally, the mechanochemical effect of ball milling was used to refine the material particles while enhancing the interfacial bonding force between porous BN, LDHs and crown ether, and successfully prepared the self-assembled porous BN@LDHs-crown ether hybrid material.

[0047] The present application then conducts an esterification reaction on the oligomer byproducts of alcoholysis of waste polyester, carboxylic acid organic matter and the above hybrid material, and then conducts a polymerization reaction to obtain a regenerated resin; in this process, the hybrid material is used to remove potassium ions in the alcoholysis byproducts of polyester, and at the same time promotes the polymerization reaction of the alcoholysis byproducts of polyester. In the present application, the alcoholysis byproducts of waste polyester are specifically the byproducts obtained after alcoholysis of waste polyester, ethylene glycol and catalyst potassium carbonate, wherein the waste polyester is selected from one or more of waste polyester fiber, waste polyester plastic and waste polyester film; the alcoholysis reaction is an alcoholysis process well known to those skilled in the art, and will not be repeated here. The carboxylic acid organic matter includes one or more of terephthalic acid, adipic acid, isophthalic acid, 4-bromophthalic acid, phthalic anhydride, p-hydroxybenzoic acid and succinic acid, and specifically, the carboxylic acid organic matter is selected from one of terephthalic acid, adipic acid, isophthalic acid, 4-bromophthalic acid, phthalic anhydride, p-hydroxybenzoic acid and succinic acid. In this process, an ester exchange stabilizer can also be added. Specifically, the ester exchange stabilizer is selected from trimethyl phosphate. The mass ratio of the polyester alcoholysis byproduct, the hybrid material, and the carboxylic acid organic matter is 600: (10-20): (120-250). Specifically, the mass ratio of the polyester alcoholysis byproduct, the hybrid material, and the carboxylic acid organic matter is 600: (15-18): (150-190). More specifically, the mass ratio of the polyester alcoholysis byproduct, the hybrid material, and the carboxylic acid organic matter is 600: 15: 150, 600: 15: 160, 600: 15: 165, 600: 15: 180, 600: 15: 190. The temperature of the esterification reaction is 100-250°C, and the time is 2-5h. Specifically, the temperature of the esterification reaction is 130-200°C, and the time is 3-4h. The vacuum degree of the polymerization reaction is 40-100Pa, the temperature is 250-300°C, and the time is 3-6h. Specifically, the vacuum degree of the polymerization reaction is 50-80Pa, the temperature is 260-285°C, and the time is 4-5h. In this application, the preparation of the regenerated resin is specifically as follows:

[0048] The alcoholysis by-product, hybrid material and carboxylic acid organic matter are put into a reactor for esterification reaction, and the distillate water and ethylene glycol are cut off at the top of the reactor. After the esterification reaction is completed, the temperature is raised to start vacuum pre-condensation. After the reaction, the temperature is continued to rise to polymerization and viscosity increase to obtain a recycled resin.

[0049] The two-dimensional material boron nitride (BN), composed of hexagonal mesh crystals composed of nitrogen atoms and boron atoms, has excellent surface physical and chemical properties and high specific surface area. It can effectively adsorb positively charged metal potassium ions, and significantly expand the contact interface through rich functional groups, enhancing the reaction active sites, thereby greatly improving the adsorption capacity and stability of metal potassium ions; layered double hydroxides (LDHs), as a type of controllable hydrotalcite-like two-dimensional material, have flexible chemical structure composition, high specific surface area and structural memory effect. The stable layer framework and interlayer anions in its structural composition can jointly maintain charge balance. The hydroxyl groups on the layer surface provide rich sites for the adsorption and chelation reaction of metal potassium ions, while the divalent and trivalent metal hydroxides in the layer skeleton can further reduce the energy barrier of polymerization chemical reactions.

[0050] Based on the above, the present invention compositely assembles porous BN micropowder, layered LDHs and crown ether metal chelators to prepare a porous BN@LDHs-crown ether hybrid material, and applies it to the catalytic polymerization of waste polyester alcoholysis byproducts, and further prepares high-value regeneration resin. This material integrates the metal ion efficient adsorption performance of porous BN and LDHs and the catalytic advantages of LDHs, and the introduction of crown ethers can accurately capture and chelate and shield potassium ions to avoid their negative impact on the polymerization reaction. At the same time, as an efficient polymerization reaction catalyst, this material can effectively improve the recovery rate of depolymerization byproducts and has important application value.

[0051] Furthermore, the present invention also discloses a method for preparing a hybrid material, comprising the following steps:

[0052] S1) mixing a divalent metal salt, a trivalent metal salt and an alkaline reagent, performing a hydrothermal reaction and then freeze-drying to obtain a layered double metal hydroxide;

[0053] S2) mixing porous boron nitride, layered double metal hydroxide, crown ether and water, freeze-drying after deposition to obtain a self-assembled solid material, and ball-milling the self-assembled solid material to obtain a porous boron nitride@double metal hydroxide-crown ether hybrid material.

[0054] In the above content, the hybrid material has been described in detail and will not be described again here.

[0055] In the process of preparing hybrid materials, porous BN was prepared by combining pore-forming agent with calcination technology. At the same time, layered LDHs were synthesized by hydrothermal method combined with freeze-drying process. Subsequently, crown ether was uniformly adsorbed and deposited on the surface of porous BN and LDHs mixture by ultrasonic dispersion to ensure that the initial deposition of crown ether was fully mixed with all components. Its structure was stabilized by freeze-drying method. Finally, ball milling method and chemical effect were used to refine the material particles while enhancing the interfacial bonding force between porous BN, LDHs and crown ether, and self-assembled porous BN@LDHs-crown ether hybrid material was successfully prepared.

[0056] The preparation method of the hybrid material of the present invention is not only simple in steps and easy to operate, but also the prepared self-assembled porous BN@LDHs-crown ether hybrid material has a unique powdery porous structure, which shows efficient adsorption and chelation ability for metal potassium ions. At the same time, in the polymerization reaction of recycled resin using waste polyester depolymerization by-products as raw materials, it shows excellent catalytic performance, and has broad practical application prospects.

[0057] In order to further understand the present invention, the preparation technology of recycled resin based on waste polyester alcoholysis byproducts provided by the present invention is described in detail below in conjunction with the examples, and the protection scope of the present invention is not limited by the following examples.

[0058] Example 1

[0059] (1) 2.50 g of boric acid, 1.82 g of urea and 0.10 g of zinc acetate were mixed and dissolved in ultrapure water, and the water was evaporated by stirring at 95 °C to obtain a white solid BN precursor; after grinding the precursor, it was heated to 800 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined for 4 h to obtain porous BN micropowder;

[0060] (2) Add 2.25 g FeSO to 100 mL ultrapure water. 4 , 1.50g Ti 2 (SO 4 ) 3 and 3.50g of sodium hydroxide, fully dissolved to form a uniform solution, then transferred to a hydrothermal kettle and placed in a 100°C oven for crystallization for 15h; after the crystallization reaction, the product was cooled to room temperature, and impurities were removed by multiple centrifugal washing, and finally freeze-dried for 10h to obtain layered Fe / Ti-LDHs;

[0061] (3) Porous BN powder, layered Fe / Ti-LDHs and 18-crown-6 were uniformly dispersed in ultrapure water in a mass ratio of 10:8:6. The mixed solution was placed in a shaker at 30 °C and subjected to oscillation deposition for 4 h. After the oscillation deposition was completed, the mixed dispersion was subjected to ultrasonic dispersion for 40 min and then freeze-dried for 30 h. The obtained solid product was placed in a ball mill and ball-milled at 400 r / min for 15 h to obtain a porous BN@Fe / Ti-LDHs@18-crown-6 hybrid material. Figure 1 This is a SEM photograph of the powdered self-assembled porous BN@Fe / Ti-LDHs@18-crown-6 hybrid material prepared in this example. It can be seen from the figure that the hybrid material has a porous structure.

[0062] The powdered porous BN@LDHs-18-crown-6 hybrid material prepared by the above method is directly used for shielding potassium ions in the depolymerization byproducts of waste polyester fibers, and is also used for polymerization catalysis of the depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained. The preparation process is as follows:

[0063] The oligomer by-products generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, porous BN@Fe / Ti-LDHs@18-crown-6 hybrid materials and terephthalic acid were used as raw materials with a mass feed ratio of 600:15:180. They were transported to the ester exchange reactor with trimethyl phosphate as an ester exchange stabilizer, slowly stirred and heated to 135°C under a nitrogen environment to carry out ester exchange reaction, during which water and ethylene glycol were continuously distilled off. After esterification reaction for 3 hours, the temperature was raised to 250°C for vacuum pre-condensation, and ethylene glycol was distilled off at the same time. After a period of reaction, the temperature was raised to 280°C and polymerization and viscosity enhancement were carried out for 4.5 hours. Finally, the recycled resin was obtained after extrusion, cooling and crystallization.

[0064] Example 2

[0065] (1) 2.50 g of boric acid, 1.85 g of melamine and 0.10 g of zinc acetate were mixed and dissolved in ultrapure water, and the water was evaporated by stirring at 85 °C to obtain a white solid BN precursor; after grinding the precursor, it was heated to 750 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined for 3 h to obtain porous BN powder;

[0066] (2) Add 2.10 g MgSO to 100 mL ultrapure water. 4 , 1.25g Ti 2 (SO 4 ) 3and 4.0 g urea, fully dissolved to form a uniform solution, then transferred to a hydrothermal kettle and placed in a 95 ° C oven for crystallization for 15 h. After the crystallization reaction is completed, the product is cooled to room temperature, washed by centrifugation several times to remove impurities, and finally freeze-dried for 10 h to obtain layered Mg / Ti-LDHs;

[0067] (3) Porous BN powder, layered Mg / Ti-LDHs and dibenzo-18-crown-6 were uniformly dispersed in ultrapure water in a mass ratio of 10:8:5. The mixed solution was placed in a shaker at 30 °C and subjected to oscillation deposition for 4 h. After the oscillation deposition was completed, the mixed dispersion was subjected to ultrasonic dispersion for 35 min and then freeze-dried for 25 h. The obtained solid product was placed in a ball mill and ball-milled at 450 r / min for 20 h to obtain a porous BN@Mg / Ti-LDHs@dibenzo-18-crown-6 hybrid material.

[0068] The powdered porous BN@Mg / Ti-LDHs@dibenzo-18-crown-6 hybrid material prepared by the above method is directly used for shielding potassium ions in the depolymerization byproducts of waste polyester fibers, and is also used for polymerization catalysis of the depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained. The preparation process is as follows:

[0069] The oligomer by-products generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, porous BN@Mg / Ti-LDHs@dibenzo-18-crown-6 hybrid materials and terephthalic acid were used as raw materials with a mass feed ratio of 600:15:160. They were transported to the ester exchange reactor with trimethyl phosphate as an ester exchange stabilizer. They were slowly stirred and heated to 130°C under a nitrogen environment to carry out the ester exchange reaction. Water and ethylene glycol were continuously distilled off during the process. After the esterification reaction for 3.5 hours, the temperature was raised to 250°C for vacuum pre-condensation, and ethylene glycol was distilled off at the same time. After a period of reaction, the temperature was raised to 285°C and polymerization and viscosity enhancement were carried out for 4 hours. Finally, the recycled resin was obtained after extrusion, cooling and crystallization.

[0070] Example 3

[0071] (1) 2.50 g of boric acid, 2.0 g of urea and 0.10 g of zinc acetate were mixed and dissolved in ultrapure water, and the water was evaporated by stirring at 90 °C to obtain a white solid BN precursor. After grinding, the precursor was heated to 850 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined for 3.5 h to obtain porous BN micropowder;

[0072] (2) Add 2.50 g CuSO to 100 mL ultrapure water. 4 , 2.0 gTi 2 (SO 4 ) 3and 4.0g of sodium hydroxide, fully dissolved to form a uniform solution, then transferred to a hydrothermal kettle, placed in a 95°C oven for crystallization for 12h. After the crystallization reaction, the product was cooled to room temperature, washed by centrifugation several times to remove impurities, and finally freeze-dried for 10h to obtain layered Cu / Ti-LDHs.

[0073] (3) Porous BN powder, layered Cu / Ti-LDHs and 18-crown-6 were uniformly dispersed in ultrapure water in a mass ratio of 10:8:6. The mixed solution was placed in a shaker at 30 °C and subjected to oscillation deposition treatment for 8 h. After the oscillation deposition was completed, the mixed dispersion was subjected to ultrasonic dispersion treatment for 45 min and then freeze-dried for 25 h. The obtained solid product was placed in a ball mill and ball-milled at 450 r / min for 20 h to obtain a porous BN@Cu / Ti-LDHs@18-crown-6 hybrid material.

[0074] The powdered porous BN@LDHs-18-crown-6 hybrid material prepared by the above method is directly used for shielding potassium ions in the depolymerization byproducts of waste polyester fibers, and is also used for polymerization catalysis of the depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained. The preparation process is as follows:

[0075] The oligomer by-products generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, porous BN@Cu / Ti-LDHs@18-crown-6 hybrid materials and adipic acid were used as raw materials with a mass feed ratio of 600:15:150. They were transported to the ester exchange reactor with trimethyl phosphate as an ester exchange stabilizer, slowly stirred and heated to 140°C under a nitrogen environment to carry out ester exchange reaction, during which water and ethylene glycol were continuously distilled off. After esterification reaction for 3 hours, the temperature was raised to 245°C for vacuum pre-condensation, and ethylene glycol was distilled off at the same time. After a period of reaction, the temperature was raised to 280°C and polymerization and viscosity enhancement were carried out for 5 hours. Finally, the recycled resin was obtained after extrusion, cooling and crystallization.

[0076] Example 4

[0077] (1) 2.50 g of metaboric acid, 2.0 g of urea and 0.10 g of zinc acetate were mixed and dissolved in ultrapure water, and the water was evaporated by stirring at 95 °C to obtain a white solid BN precursor. After grinding, the precursor was heated to 900 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined for 3.5 h to obtain porous BN micropowder;

[0078] (2) Add 2.50 g ZnSO to 100 mL ultrapure water. 4 , 1.80g Ti 2 (SO 4 ) 3and 3.5g of sodium hydroxide, fully dissolved to form a uniform solution, then transferred to a hydrothermal kettle, placed in a 95°C oven for crystallization for 15h. After the crystallization reaction, the product was cooled to room temperature, washed by centrifugation several times to remove impurities, and finally freeze-dried for 10h to obtain layered Zn / Ti-LDHs.

[0079] (3) Porous BN powder, layered Zn / Ti-LDHs and 18-crown-6 were uniformly dispersed in ultrapure water in a mass ratio of 10:8:6. The mixed solution was placed in a shaker at 30 °C and subjected to oscillation deposition treatment for 10 h. After the oscillation deposition was completed, the mixed dispersion was ultrasonically dispersed for 50 min and then freeze-dried for 25 h. The obtained solid product was placed in a ball mill and ball-milled at 500 r / min for 20 h to obtain a porous BN@Zn / Ti-LDHs@18-crown-6 hybrid material.

[0080] The powdered porous BN@Zn / Ti-LDHs@18-crown-6 hybrid material prepared by the above method is directly used for shielding potassium ions in the depolymerization byproducts of waste polyester fibers, and is also used for polymerization catalysis of the depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained. The preparation process is as follows:

[0081] The oligomer by-products generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, porous BN@Zn / Ti-LDHs@18-crown-6 hybrid materials and isophthalic acid were used as raw materials with a mass feed ratio of 600:15:165. They were transported to the ester exchange reactor with trimethyl phosphate as an ester exchange stabilizer. They were slowly stirred and heated to 130°C under a nitrogen environment to carry out the ester exchange reaction. Water and ethylene glycol were continuously distilled off during the process. After 3.5 hours of esterification reaction, the temperature was raised to 245°C for vacuum pre-condensation, and ethylene glycol was distilled off at the same time. After a period of reaction, the temperature was raised to 280°C, and polymerization and viscosity enhancement were carried out for 5 hours. Finally, the recycled resin was obtained after extrusion, cooling and crystallization.

[0082] Example 5

[0083] (1) 2.50 g of boron chloride, 2.0 g of dicyandiamide and 0.10 g of copper sulfate were mixed and dissolved in ultrapure water, and the water was evaporated by stirring at 95 °C to obtain a white solid BN precursor. After grinding, the precursor was heated to 800 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined for 5 h to obtain porous BN powder;

[0084] (2) Add 2.25 g NiSO to 100 mL ultrapure water. 4 , 2.0g Ti 2 (SO 4 ) 3and 5g of sodium hydroxide, fully dissolved to form a uniform solution, then transferred to a hydrothermal kettle, placed in a 95°C oven for crystallization for 18h. After the crystallization reaction is completed, the product is cooled to room temperature, washed by centrifugation several times to remove impurities, and finally freeze-dried for 12h to obtain layered Ni / Ti-LDHs;

[0085] (3) Porous BN powder, layered Ni / Ti-LDHs and dibenzo-30-crown-10 were uniformly dispersed in ultrapure water in a mass ratio of 10:8:6. The mixed solution was placed in a shaker at 30 °C and subjected to oscillation deposition for 10 h. After the oscillation deposition was completed, the mixed dispersion was ultrasonically dispersed for 50 min and then freeze-dried for 30 h. The obtained solid product was placed in a ball mill and ball-milled at 450 r / min for 25 h to obtain a porous BN@Ni / Ti-LDHs@dibenzo-30-crown-10 hybrid material.

[0086] The powdered porous BN@Ni / Ti-LDHs@dibenzo-30-crown-10 hybrid material prepared by the above method is directly used for shielding potassium ions in the depolymerization byproducts of waste polyester fibers, and is also used for polymerization catalysis of the depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained. The preparation process is as follows:

[0087] The oligomer by-products generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, porous BN@Ni / Ti-LDHs@dibenzo-30-crown-10 hybrid materials and 4-bromophthalic acid were used as raw materials with a mass feed ratio of 600:15:190. They were transported to the ester exchange reactor with trimethyl phosphate as an ester exchange stabilizer. They were slowly stirred and heated to 130°C under a nitrogen environment to carry out the ester exchange reaction. Water and ethylene glycol were continuously distilled off during the process. After the esterification reaction for 4 hours, the temperature was raised to 250°C for vacuum pre-condensation, and ethylene glycol was distilled off at the same time. After a period of reaction, the temperature was raised to 285°C, and polymerization and viscosity enhancement were carried out for 5 hours. Finally, the recycled resin was obtained after extrusion, cooling and crystallization.

[0088] Example 6

[0089] (1) 2.50 g of boron sulfide, 2.0 g of urea and 0.10 g of copper sulfate were mixed and dissolved in ultrapure water, and the water was evaporated by stirring at 95 °C to obtain a white solid BN precursor. After grinding, the precursor was heated to 850 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined for 5 h to obtain porous BN powder;

[0090] (2) Add 1.25 g FeSO to 100 mL ultrapure water. 4 , 1.25 g CuSO 4 , 2.0 g Ti 2 (SO 4 ) 3and 4.0g of sodium hydroxide, fully dissolved to form a uniform solution, then transferred to a hydrothermal kettle, placed in a 95°C oven for crystallization for 20h. After the crystallization reaction, the product was cooled to room temperature, washed by centrifugation several times to remove impurities, and finally freeze-dried for 10h to obtain layered Fe / Cu / Ti-LDHs.

[0091] (3) Porous BN powder, layered Fe / Cu / Ti-LDHs and 15-crown-5 were uniformly dispersed in ultrapure water in a mass ratio of 10:7:5. The mixed solution was placed in a shaker at 30 °C and subjected to oscillation deposition treatment for 12 h. After the oscillation deposition was completed, the mixed dispersion was ultrasonically dispersed for 60 min and then freeze-dried for 30 h. The obtained solid product was placed in a ball mill and ball-milled at 450 r / min for 25 h to obtain a porous BN@Fe / Cu / Ti-LDHs@15-crown-5 hybrid material.

[0092] The powdered porous BN@Fe / Cu / Ti-LDHs@15-crown-5 hybrid material prepared by the above method is directly used for shielding potassium ions in the depolymerization byproducts of waste polyester fibers, and is also used for polymerization catalysis of the depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained. The preparation process is as follows:

[0093] The oligomer by-products generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, porous BN@Fe / Cu / Ti-LDHs@15-crown-5 hybrid materials and phthalic anhydride were used as raw materials with a mass feed ratio of 600:15:150. They were transported to the ester exchange reactor with trimethyl phosphate as an ester exchange stabilizer. They were slowly stirred and heated to 130°C under a nitrogen environment to carry out the ester exchange reaction. Water and ethylene glycol were continuously distilled off during the process. After 4.5 hours of esterification reaction, the temperature was raised to 250°C for vacuum pre-condensation, and ethylene glycol was distilled off at the same time. After a period of reaction, the temperature was raised to 285°C, and polymerization and viscosity enhancement were carried out for 5 hours. Finally, the recycled resin was obtained after extrusion, cooling and crystallization.

[0094] Example 7

[0095] (1) 2.50 g of sodium borohydride, 1.5 g of sodium azide and 0.10 g of ferric sulfate were mixed and dissolved in ultrapure water, and the water was evaporated by stirring at 90 °C to obtain a white solid BN precursor. After grinding, the precursor was heated to 700 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined for 5 h to obtain porous BN powder;

[0096] (2) Add 1.5 g ZnCl to 100 mL ultrapure water. 2 , 0.5g NiSO 4 , 2.0g Ti 2 (SO 4 ) 3and 4.5g of sodium hydroxide, fully dissolved to form a uniform solution, then transferred to a hydrothermal kettle, placed in a 95°C oven for crystallization for 20h. After the crystallization reaction, the product was cooled to room temperature, washed by centrifugation several times to remove impurities, and finally freeze-dried for 8h to obtain layered Zn / Ni / Ti-LDHs.

[0097] (3) Porous BN powder, layered Zn / Ni / Ti-LDHs and cyclohexane-18-crown-6 were uniformly dispersed in ultrapure water in a mass ratio of 10:8:6. The mixed solution was placed in a shaker at 30 °C and subjected to oscillation deposition for 10 h. After the oscillation deposition was completed, the mixed dispersion was subjected to ultrasonic dispersion for 60 min and then freeze-dried for 25 h. The obtained solid product was placed in a ball mill and ball-milled at 420 r / min for 20 h to obtain a porous BN@Zn / Ni / Ti-LDHs@cyclohexane-18-crown-6 hybrid material.

[0098] The powdered porous BN@Zn / Ni / Ti-LDHs@cyclohexane-18-crown-6 hybrid material prepared by the above method is directly used for shielding potassium ions in the depolymerization byproducts of waste polyester fibers, and is also used for polymerization catalysis of the depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained. The preparation process is as follows:

[0099] The oligomer byproducts generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, porous BN@Zn / Ni / Ti-LDHs@cyclohexane-18-crown-6 materials, and p-hydroxybenzoic acid were used as raw materials, with a mass feed ratio of 600:15:180, and trimethyl phosphate was used as an ester exchange stabilizer. They were slowly stirred and heated to 135°C under a nitrogen environment to carry out ester exchange reaction. Water and ethylene glycol were continuously distilled during the process. After esterification reaction for 4 hours, the temperature was raised to 250°C for vacuum pre-condensation, and ethylene glycol was distilled at the same time. After a period of reaction, the temperature was raised to 285°C, and polymerization and viscosity enhancement were carried out for 5 hours. Finally, the recycled resin was obtained after extrusion, cooling and crystallization.

[0100] Example 8

[0101] (1) 2.25 g of ammonia borane, 2.0 g of urea and 0.10 g of zinc sulfate were mixed and dissolved in ultrapure water, and the water was evaporated by stirring at 90 °C to obtain a white solid BN precursor. After grinding, the precursor was heated to 800 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined for 5 h to obtain porous BN powder;

[0102] (2) Add 1.25 g FeSO to 100 mL ultrapure water. 4 , 1.0g NiSO 4 , 2.0g Ti 2 (SO 4 )3 and 5.0g sodium hydroxide, fully dissolved to form a uniform solution, then transferred to a hydrothermal kettle, placed in a 95°C oven for crystallization for 20h. After the crystallization reaction, the product was cooled to room temperature, washed by centrifugation several times to remove impurities, and finally freeze-dried for 10h to obtain layered Fe / Ni / Ti-LDHs.

[0103] (3) Porous BN powder, layered Fe / Ni / Ti-LDHs and 18-crown-6 were uniformly dispersed in ultrapure water in a mass ratio of 10:8:6. The mixed solution was placed in a shaker at 30 °C and subjected to oscillation deposition for 10 h. After the oscillation deposition was completed, the mixed dispersion was subjected to ultrasonic dispersion for 60 min and then freeze-dried for 25 h. The obtained solid product was placed in a ball mill and ball-milled at 420 r / min for 20 h to obtain a porous BN@Fe / Ni / Ti-LDHs@18-crown-6 hybrid material.

[0104] The powdered porous BN@Fe / Ni / Ti-LDHs@18-crown-6 hybrid material prepared by the above method is directly used for shielding potassium ions in the depolymerization byproducts of waste polyester fibers, and is also used for polymerization catalysis of the depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained. The preparation process is as follows:

[0105] The oligomer by-products generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, porous BN@Fe / Ni / Ti-LDHs@18-crown-6 chemical materials and succinic acid were used as raw materials with a mass feed ratio of 600:15:180. They were transported to the ester exchange reactor with trimethyl phosphate as an ester exchange stabilizer. They were slowly stirred and heated to 135°C under a nitrogen environment to carry out the ester exchange reaction. Water and ethylene glycol were continuously distilled off during the process. After esterification reaction for 4 hours, the temperature was raised to 250°C for vacuum pre-condensation, and ethylene glycol was distilled off at the same time. After a period of reaction, the temperature was raised to 280°C, and polymerization and viscosity enhancement were carried out for 5 hours. Finally, the recycled resin was obtained after extrusion, cooling and crystallization.

[0106] Comparative Example 1

[0107] 2.50 g of boric acid, 1.82 g of urea and 0.10 g of zinc acetate were mixed and dissolved in ultrapure water, and the water was evaporated by stirring at 95 °C to obtain a white solid BN precursor. After grinding, the precursor was heated to 800 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined for 4 h to obtain porous BN powder.

[0108] The porous BN powder prepared by the above method is directly used for shielding potassium ions in the depolymerization byproducts of waste polyester fibers, and is also used for polymerization catalysis of the depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained. The preparation process is as follows:

[0109] Firstly, the oligomer by-products generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, porous BN micropowder and terephthalic acid are used as raw materials with a mass feed ratio of 600:15:180. They are transported to the ester exchange reactor with trimethyl phosphate as an ester exchange stabilizer. The mixture is slowly stirred and heated to 135°C under a nitrogen environment to carry out the ester exchange reaction. Water and ethylene glycol are continuously distilled off during the process. After the esterification reaction for 3 hours, the temperature is raised to 250°C for vacuum pre-condensation, and ethylene glycol is distilled off at the same time. After a period of reaction, the temperature is raised to 280°C, and polymerization and viscosity enhancement are carried out for 4.5 hours. Finally, the recycled resin is obtained after extrusion, cooling and crystallization.

[0110] Comparative Example 2

[0111] In 100 mL of ultrapure water, add 2.25 g of FeSO 4 , 1.50g Ti 2 (SO 4 ) 3 and 3.50 g of sodium hydroxide, fully dissolved to form a uniform solution, then transferred to a hydrothermal kettle and placed in a 100 °C oven for crystallization for 15 h. After the crystallization reaction is completed, the product is cooled to room temperature, and impurities are removed by multiple centrifugal washings, and finally freeze-dried for 10 h to obtain layered Fe / Ti-LDHs.

[0112] The layered Fe / Ti-LDHs prepared by the above method is directly used for metal shielding of potassium ions remaining in the depolymerization process of waste polyester, and is also used as a polymerization catalyst for depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained, including the following process:

[0113] The oligomer by-products generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, layered Fe / Ti-LDHs materials, and terephthalic acid are used as raw materials with a mass feed ratio of 600:15:180. Trimethyl phosphate is used as an ester exchange stabilizer. They are transported to an ester exchange reactor together, slowly stirred and heated to 135°C under a nitrogen environment to carry out an ester exchange reaction. Water and ethylene glycol are continuously distilled off during the process. After the esterification reaction for 3 hours, the temperature is raised to 250°C for vacuum pre-condensation, and ethylene glycol is distilled off at the same time. After a period of reaction, the temperature is raised to 280°C, and polymerization and viscosity enhancement are carried out for 4.5 hours. Finally, the recycled resin is obtained after extrusion, cooling and crystallization.

[0114] Comparative Example 3

[0115] (1) 2.50 g of boric acid, 1.82 g of urea and 0.10 g of zinc acetate were mixed and dissolved in ultrapure water, and the water was evaporated by stirring at 95 °C to obtain a white solid BN precursor. After grinding, the precursor was heated to 800 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined for 4 h to obtain porous BN powder;

[0116] (2) Add 2.25 g FeSO to 100 mL ultrapure water. 4 , 1.50g Ti 2 (SO 4 ) 3 and 3.50g of sodium hydroxide, fully dissolved to form a uniform solution, then transferred to a hydrothermal kettle, placed in an oven at 100°C for crystallization for 12h. After the crystallization reaction is completed, the product is cooled to room temperature, washed by centrifugation several times to remove impurities, and finally freeze-dried for 12h to obtain layered Fe / Ti-LDHs;

[0117] (3) The porous BN powder and layered Fe / Ti-LDHs were uniformly dispersed in ultrapure water in a mass ratio of 8:6. The mixed solution was placed in a shaker at 30 °C and subjected to oscillation deposition for 4 h. After the oscillation deposition was completed, the mixed dispersion was subjected to ultrasonic dispersion for 45 min and then freeze-dried for 25 h. The obtained solid product was placed in a ball mill and ball-milled at 425 r / min for 15 h to obtain a porous BN@Fe / Ti-LDHs hybrid material.

[0118] The porous BN@Fe / Ti-LDHs hybrid material prepared by the above method is directly used for metal shielding of potassium ions remaining in the depolymerization process of waste polyester, and is also used as a polymerization catalyst for depolymerization byproducts and carboxylic acid organic matter, and finally a recycled resin is obtained, including the following processes:

[0119] The oligomer by-products generated by the depolymerization of waste polyester fibers by ethylene glycol alcoholysis, porous BN@Fe / Ti-LDHs hybrid materials, and terephthalic acid were used as raw materials with a mass feed ratio of 600:15:180. They were transported to the ester exchange reactor with trimethyl phosphate as an ester exchange stabilizer. They were slowly stirred and heated to 130°C under a nitrogen environment to carry out the ester exchange reaction. Water and ethylene glycol were continuously distilled off during the process. After 3.5 hours of esterification reaction, the temperature was raised to 255°C for vacuum pre-condensation, and ethylene glycol was distilled off at the same time. After a period of reaction, the temperature was raised to 280°C, and polymerization and viscosity enhancement were carried out for 5 hours. Finally, the recycled resin was obtained after extrusion, cooling and crystallization.

[0120] The properties of the regenerated resins prepared in the examples and comparative examples were tested, and the results are shown in Table 1;

[0121] Table 1 Performance data of recycled resin synthesized from depolymerization byproducts

[0122]

[0123] As can be seen from Table 1, by adjusting the boron source, nitrogen source and pore-forming agent in the preparation process of porous BN, and by optimizing the mass addition ratio of divalent and trivalent metal salts and the type of alkaline reagent in layered LDHs, and finally self-assembling with crown ethers, the prepared hybrid materials have achieved good results in the shielding effect on potassium ions and the catalytic efficiency of the polymerization reaction in the polymerization reaction of by-products with different carboxylic acid organics.

[0124] The results of Comparative Examples 1, 2 and 3 show that under the same carboxylic acid organic polymerization raw material conditions, the recycled resins prepared by introducing porous BN micropowder or layered Fe / Ti-LDHs alone all exhibit lower fracture strength, higher diethylene glycol content and smaller intrinsic viscosity; although the use of porous BN@Fe / Ti-LDHs hybrid material as a catalyst for the alcoholysis of waste polyester can improve the performance of the recycled resin, compared with the self-assembled BN@LDHs-crown ether hybrid material composed of porous BN, layered LDHs and crown ether in the present invention, it is still insufficient in terms of potassium ion shielding effect and polymerization reaction catalytic activity. Therefore, there is an obvious synergistic effect between porous BN, layered LDHs and crown ether.

[0125] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0126] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a recycled resin based on waste polyester alcoholysis byproducts, comprising the following steps: S1) mixing a divalent metal salt, a trivalent metal salt and an alkaline reagent, performing a hydrothermal reaction and then freeze-drying to obtain a layered double metal hydroxide; the divalent metal cations in the divalent metal salt include Fe 2+ 、Ni 2+ , Cu 2+ 、Zn 2+ and Mg 2+ One or two of the following; the trivalent metal cation in the trivalent metal salt is Ti 3+ ; S2) mixing porous boron nitride, layered double metal hydroxide, crown ether and water, freeze-drying after deposition to obtain a self-assembled solid material, and ball-milling the self-assembled solid material to obtain a porous boron nitride@double metal hydroxide-crown ether hybrid material; S3) subjecting the oligomer byproduct of alcoholysis of waste polyester, carboxylic acid organic matter and the hybrid material to an esterification reaction, and then to a polymerization reaction to obtain a recycled resin.

2. The preparation method according to claim 1, characterized in that: The preparation method of the porous boron nitride is specifically as follows: A boron source, a nitrogen source, a pore former and water are mixed and heated to obtain a boron nitride precursor; The boron nitride precursor is calcined to obtain porous boron nitride.

3. The preparation method according to claim 2, characterized in that: The boron source includes one or more of boric acid, ammonia borane, metaboric acid, boron chloride, boron oxide, boron sulfide and sodium borohydride; the nitrogen source includes one or more of urea, melamine, sodium azide, dicyandiamide and sodium amide; the pore former includes one or more of zinc acetate, nickel sulfate, cobalt sulfate, iron sulfate, copper sulfate and zinc sulfate; And / or, the mass ratio of the boron source to the nitrogen source is 10:(3-8); And / or, the calcination temperature is 500-1500° C., the time is 3-10 hours, and the calcination is carried out under a protective atmosphere, and the protective atmosphere is nitrogen or argon.

4. The preparation method according to claim 1 or 2, characterized in that: In step S1), the anions in the divalent metal salt and the trivalent metal salt are independently selected from SO4 2- 、NO 3- 、CO3 2- and Cl - One or more of; and / or, the alkaline agent includes one of urea, ammonia water and sodium hydroxide.

5. The preparation method according to claim 4, characterized in that: In step S1), the mass ratio of the divalent metal salt to the trivalent metal salt is (1-5):1, and the ratio of the total mass of the divalent metal salt and the trivalent metal salt to the mass of the alkaline reagent is 1:(0.5-5); and / or, the temperature of the hydrothermal reaction is 50-100°C, and the time is 10-25h; and / or, the freeze-drying time is 10-15h.

6. The preparation method according to claim 1 or 2, characterized in that: In step S2), the crown ether includes one or more of 18-crown-6, dibenzo-18-crown-6, dibenzo-30-crown-10, 15-crown-5 and cyclohexanedo-18-crown-6; And / or, the mass ratio of the porous boron nitride, the layered double hydroxide and the crown ether is 10:(5-10):(3-8).

7. The preparation method according to claim 1 or 2, characterized in that: In step S2), the deposition temperature is 20-80°C and the deposition time is 3-15h; And / or, the deposition further includes ultrasonic dispersion, and the ultrasonic dispersion time is 20 to 60 minutes; And / or, the freeze-drying time is 20 to 40 hours; And / or, the masses of the grinding beads of the ball mill are 2.5 g, 10 g, 14 g, 15 g, and 55 g, respectively, with the corresponding quantity ratio being (14-16): (9-11): (4-6): (4-6): (2-4), the ball milling time is 10-30 h, and the rotation speed is 300-500 r / min.

8. The preparation method according to claim 1 or 2, characterized in that: In step S3), the waste polyester includes one or more of waste polyester fibers, waste polyester plastics and waste polyester films; and / or, the carboxylic acid organic compound comprises one or more of terephthalic acid, adipic acid, isophthalic acid, 4-bromophthalic acid, phthalic anhydride, p-hydroxybenzoic acid and succinic acid; And / or, the mass ratio of the oligomer by-product, the carboxylic acid organic matter and the hybrid material is 600: (120-250): (10-20).

9. The preparation method according to claim 1 or 2, characterized in that: The temperature of the esterification reaction is 100-250° C., and the time is 2-5 hours; the vacuum degree of the polymerization reaction is 40-100 Pa, the temperature is 200-300° C., and the time is 3-6 hours.

10. A method for preparing a hybrid material, comprising the following steps: S1) mixing a divalent metal salt, a trivalent metal salt and an alkaline reagent, performing a hydrothermal reaction and then freeze-drying to obtain a layered double metal hydroxide; the divalent metal cations in the divalent metal salt include Fe 2+ 、Ni 2+ , Cu 2+ 、Zn 2+ and Mg 2+ One or two of the following; the trivalent metal cation in the trivalent metal salt is Ti 3+ ; S2) mixing porous boron nitride, layered double metal hydroxide, crown ether and water, freeze-drying after deposition to obtain a self-assembled solid material, and ball-milling the self-assembled solid material to obtain a porous boron nitride@double metal hydroxide-crown ether hybrid material.

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