Modified PET recycled material and preparation method thereof

Abstract

The invention discloses a modified PET recycled material and a preparation method thereof, and belongs to the technical field of plastic recycling. Comprising the following raw materials in parts by weight: 70-90 parts of a pretreated PET reclaimed material, 8-24 parts of modified graphene oxide, 3-9 parts of an antioxidant and 3-5 parts of a lubricant. Wherein the antioxidant can achieve a synergistic effect, so that the oxidation resistance of the PET recycled material is greatly improved; wherein the modified graphene oxide has good compatibility with a PET matrix, and can play a synergistic effect with groups on the surface of the modified graphene oxide, so that the flame retardance, antibacterial property and certain heat resistance of the PET recycled material are remarkably enhanced; therefore, the PET recycled material is modified and recycled, the pollution of waste materials is reduced, the recycling of resources is realized, and the modified PET recycled material also has excellent oxidation resistance, stable and efficient flame retardance, antibacterial property and heat resistance to a certain degree, and has important application value in the technical field of plastic recycling.

Description

Technical Field

[0001] The invention belongs to the technical field of plastic recycling, and in particular relates to a modified PET recycled material and a preparation method thereof. Background Art

[0002] With the continuous attention and promotion of environmental protection and sustainable development, the PET recycling market has shown a good growth trend. People can alleviate the environmental pollution caused by plastics to a certain extent by recycling PET waste. PET is polyethylene terephthalate, which is obtained by polymerizing dimethyl terephthalate (DMT) or terephthalic acid (PTA) with ethylene glycol. Because of its relatively low production cost, it can reduce the demand for new raw materials, save energy, reduce carbon emissions, and conform to environmental protection concepts. Therefore, PET recycling is increasingly becoming the preferred raw material for industries such as consumer product packaging and textiles.

[0003] The large number of benzene rings in the PET molecular chain endows it with high strength, high rigidity, good heat resistance, dimensional stability and chemical resistance. Due to its excellent performance, it is widely used in fibers, films and beverage bottles. However, waste PET contains various impurities, which deteriorate the tensile strength of recycled PET and reduce the uniformity of recycled PET. Although the recycling rate of waste PET has been increasing year by year, most of it is "downgraded" to produce low-grade fibers, films and non-edible packaging bottles, while the proportion of "upgraded" used as high-performance engineering plastics is very low, which is a major gap in the market. Therefore, it is urgent to invent a modified PET recycled material to meet the higher demands in the field of plastic recycling technology. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a modified PET recycled material and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing modified PET recycled material comprises the following steps:

[0007] The pretreated PET recycled material, modified graphene oxide, antioxidant and lubricant are mixed and added into a twin-screw extruder, melt-blended, extruded and granulated to obtain the modified PET recycled material.

[0008] Furthermore, the raw materials are calculated in parts by weight as follows: 70-90 parts of pre-treated PET recycled material, 8-24 parts of modified graphene oxide, 3-9 parts of antioxidant, and 3-5 parts of lubricant.

[0009] Furthermore, the antioxidant is prepared by compounding a hindered phenol antioxidant and a thioester antioxidant in a mass ratio of 2:1.

[0010] Furthermore, the lubricant is one of paraffin and stearamide fatty acid.

[0011] The added antioxidants are hindered phenol antioxidants and phosphite auxiliary antioxidants, which can play a synergistic role and greatly improve the antioxidant properties of PET recycled materials.

[0012] Furthermore, the pretreated PET recycled material is prepared by the following steps:

[0013] The PET recycled material was added to a pulverizer and crushed, then added to water, stirred for 5 minutes, and then sodium dodecyl sulfate was added. The stirring was continued for 30 minutes, filtered, washed with water for 3-4 times, dried in an oven at 100°C for 2 hours, and then added to tetrahydrofuran. After stirring for 30 minutes, filtered, the filter cake was washed with ethanol solution, and dried in an oven at 80°C for 1 hour to obtain the pretreated PET recycled material.

[0014] Furthermore, the ratio of the amount of the PET recycled material, water, sodium dodecyl sulfate and tetrahydrofuran is 1 g:40 mL:2.4 g:20 mL.

[0015] By crushing and washing the recycled PET materials, impurities in the recycled PET materials can be effectively removed.

[0016] Furthermore, the modified graphene oxide is prepared by the following steps:

[0017] S1. In a three-necked flask equipped with a stirring device, tris(hydroxymethyl)aminomethane hydrochloride, triethylamine and N,N-dimethylformamide (DMF) were mixed at room temperature, placed in an ice-water bath at 3°C, and stirred for 30 minutes. Then, phosphorus oxychloride was slowly added dropwise, and the temperature was controlled not to exceed 20°C during the addition. After the addition was completed, the temperature was raised to 85°C and kept for reaction for 7 hours. After the reaction was completed, the solvent was removed by filtration under reduced pressure, and the filter cake was washed 3-4 times with anhydrous ethanol, and vacuum dried to obtain intermediate 1; the ratio of tris(hydroxymethyl)aminomethane hydrochloride, triethylamine, N,N-dimethylformamide and phosphorus oxychloride was 16.1g:15mL:100mL:15.3g;

[0018] Tris(hydroxymethyl)aminomethane hydrochloride reacts with phosphorus oxychloride to obtain intermediate 1; the specific reaction process is as follows:

[0019]

[0020] S2. Under nitrogen protection at room temperature, add 4,4'-sulfonyl dibenzoic acid and toluene to a three-necked flask equipped with a stirring device, heat to 35°C and stir continuously, add intermediate 1 and dicyclohexylcarbodiimide (DCC, dehydrating agent) and mix and stir evenly, control the reaction temperature to 55°C, keep the temperature to react for 2h, filter after the reaction, remove the solvent by vacuum distillation, wash with anhydrous ethanol 2-3 times, and vacuum dry to obtain intermediate 2; the ratio of 4,4'-sulfonyl dibenzoic acid, toluene, intermediate 1, and dicyclohexylcarbodiimide is 32.4g:150mL:16.5g:20.6g;

[0021] The carboxyl group on 4,4'-sulfonyl dibenzoic acid and the amino group of intermediate 1 undergo an amidation reaction. Under the action of DCC, the reaction can be carried out under relatively mild conditions. By controlling the molar ratio of the two to be close to 1:1 and a slight excess of 4,4'-sulfonyl dibenzoic acid, only one carboxyl group on 4,4'-sulfonyl dibenzoic acid participates in the reaction to obtain intermediate 2. The specific reaction process is as follows:

[0022]

[0023] S3. Add 3,5-diaminopyridine, intermediate 2, dicyclohexylcarbodiimide and N,N-dimethylformamide to a three-necked flask equipped with a stirring device, stir and mix well, place in a water bath at 60°C, heat in a water bath for 5 hours, filter after the reaction, remove the solvent by vacuum distillation, and purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, the volume ratio of the two is 2:3), remove the eluent by rotary evaporation to obtain intermediate 3; the ratio of 3,5-diaminopyridine, intermediate 2, dicyclohexylcarbodiimide and N,N-dimethylformamide is 13.3 g:45.3 g:20.6 g:150 mL;

[0024] Under the action of dicyclohexylcarbodiimide, 3,5-diaminopyridine and intermediate 2 undergo amidation reaction. By controlling the molar ratio of the two to be close to 1:1 and a slight excess of 3,5-diaminopyridine, only one amino group on 3,5-diaminopyridine participates in the reaction to obtain intermediate 3. The specific reaction process is as follows:

[0025]

[0026] S4. After mixing the intermediate 3 and N,N-dimethylformamide in a three-necked flask equipped with a stirring device, dicyclohexylcarbodiimide was added and stirred evenly; then, graphene oxide dispersion (DMF was used as a dispersion medium with a concentration of 10 mg / mL) was slowly added while stirring, ultrasonic treatment was performed for 15 min, and the mixture was heated to 60°C and kept warm for 8 h. Stirring was continued during the reaction. After the reaction was completed, vacuum distillation, ethyl acetate washing, and freeze-drying were performed to obtain pre-modified graphene oxide; the ratio of the amount of intermediate 3, N,N-dimethylformamide, dicyclohexylcarbodiimide, and graphene oxide dispersion was 6.4 g:100 mL:2.3 g:100 mL;

[0027] Under the action of dicyclohexylcarbodiimide, the amino group of intermediate 3 undergoes an amidation reaction with the carboxyl group on the surface of graphene oxide, and the amino group on intermediate 3 is grafted onto graphene oxide to obtain pre-modified graphene oxide. The specific reaction process is as follows:

[0028]

[0029] S5. Add pre-modified graphene oxide and N,N-dimethylformamide to a three-necked flask equipped with a reflux device, disperse them evenly by ultrasonication, and then slowly drop ethyl bromide. After the dropwise addition is completed, place it in a water bath at 55°C, reflux for 6 hours, and after the reaction is completed, distill under reduced pressure, wash with ethanol, cool and dry to obtain modified graphene oxide; the ratio of pre-modified graphene oxide, N,N-dimethylformamide, and ethyl bromide is 1g:100mL:6.5mL;

[0030] The pre-modified graphene oxide undergoes a quaternization reaction with ethyl bromide to obtain modified graphene oxide; the structure of the modified graphene oxide is shown below:

[0031]

[0032] Graphene oxide is an important derivative of graphene-based materials. It has excellent performance and certain flame retardant and antibacterial properties. By modifying the surface of graphene oxide and increasing the hydrophobic groups on the surface of graphene oxide, the compatibility of graphene oxide with PET matrix can be enhanced, so that the performance of graphene oxide can be fully exerted. In addition, the modified graphene oxide also contains diphenyl sulfone, caged phosphonate and pyridinium quaternary ammonium salt structures, among which diphenyl sulfone has good heat resistance and is desulfurized by heat to generate SO2, sulfurous acid and water, which can promote the Fries rearrangement reaction of the matrix and accelerate the carbonization of the matrix, which can effectively enhance the matrix's resistance to fire. In addition, the diphenyl sulfone structure contains benzene rings, which can further enhance the compatibility of modified graphene oxide with the matrix. The introduced caged phosphonate structure is a green and environmentally friendly flame retardant with strong stability. It can promote the formation of carbon layer and inhibit smoke release during combustion. It can synergize with graphene oxide and diphenyl sulfone to greatly enhance the flame retardant properties of the matrix. Finally, the introduced pyridinium quaternary ammonium salt is a new type of quaternary ammonium salt with more concentrated positive charge and stronger bactericidal ability, which avoids the problem of bacterial resistance caused by the long-term use of quaternary ammonium salt antibacterial agents. It can synergize with graphene oxide to greatly enhance the antibacterial properties of the matrix.

[0033] It should be added that the organic small molecules are connected to graphene oxide, which can effectively protect the organic small molecules, improve their resistance to migration and permeation, and ensure the long-term stability of the performance of the modified graphene oxide.

[0034] Beneficial effects of the present invention:

[0035] 1. The modified PET recycled material prepared by the present invention removes some impurities of the PET recycled material by pre-treating the PET recycled material, making the raw material purer;

[0036] 2. The added antioxidant can play a synergistic role and greatly improve the antioxidant properties of PET recycled materials;

[0037] 3. Compared with ordinary graphene oxide, the modified graphene oxide has better compatibility with the PET matrix and can play a synergistic role with the groups on its surface, significantly enhancing the flame retardancy, antibacterial properties and heat resistance of PET recycled materials to a certain extent;

[0038] Therefore, the present invention reduces waste pollution and realizes resource recycling by modifying and reusing PET recycled materials. The modified PET recycled materials also have excellent antioxidant properties, stable and efficient flame retardancy, antibacterial properties and a certain degree of heat resistance, and have important application value in the field of plastic recycling technology. DETAILED DESCRIPTION

[0039] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Embodiment 1

[0041] Preparation of modified graphene oxide:

[0042] S1. In a three-necked flask equipped with a stirring device, 16.1 g of tris(hydroxymethyl)aminomethane hydrochloride, 15 mL of triethylamine and 100 mL of N,N-dimethylformamide were mixed at room temperature, placed in an ice-water bath at 3°C, and stirred for 30 min. Then, 15.3 g of phosphorus oxychloride was slowly added dropwise, and the temperature was controlled not to exceed 20°C during the addition. After the addition was completed, the temperature was raised to 85°C and kept for reaction for 7 h. After the reaction was completed, the solvent was removed by filtration under reduced pressure, and the filter cake was washed 3 times with anhydrous ethanol and dried in vacuo to obtain intermediate 1.

[0043] S2. Under nitrogen protection at room temperature, add 32.4 g of 4,4'-sulfonyldibenzoic acid and 150 mL of toluene to a three-necked flask equipped with a stirring device, heat to 35°C and stir continuously, add 16.5 g of intermediate 1 and 20.6 g of dicyclohexylcarbodiimide, mix and stir evenly, control the reaction temperature to 55°C, keep the temperature for 2 hours, filter after the reaction, remove the solvent by vacuum distillation, wash with anhydrous ethanol 2-3 times, and vacuum dry to obtain intermediate 2;

[0044] S3, in a three-necked flask equipped with a stirring device, add 13.3g 3,5-diaminopyridine, 45.3g intermediate 2, 20.6g dicyclohexylcarbodiimide and 150mL N,N-dimethylformamide, stir and mix well, place in a 60°C water bath, heat in a water bath for 5h, filter after the reaction, remove the solvent by vacuum distillation, and purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, the volume ratio of the two is 2:3), and remove the eluent by rotary evaporation to obtain intermediate 3;

[0045] S4. After mixing 6.4 g of intermediate 3 with 100 mL of N,N-dimethylformamide in a three-necked flask equipped with a stirring device, 2.3 g of dicyclohexylcarbodiimide was added and stirred evenly; then 100 mL of graphene oxide dispersion (DMF as a dispersion medium with a concentration of 10 mg / mL) was slowly added while stirring, ultrasonically treated for 15 min, heated to 60° C., and kept warm for 8 h, stirring continuously during the reaction. After the reaction was completed, vacuum distillation, ethyl acetate washing, and freeze-drying were performed to obtain pre-modified graphene oxide;

[0046] S5. Add 1 g of pre-modified graphene oxide and 100 mL of N,N-dimethylformamide to a three-necked flask equipped with a reflux device, and disperse them evenly by ultrasonication. Then slowly drop 6.5 mL of ethyl bromide. After the addition is complete, place the mixture in a water bath at 55°C and reflux for 6 hours. After the reaction is complete, evaporate under reduced pressure, wash with ethanol, and cool and dry to obtain modified graphene oxide.

[0047] Embodiment 2

[0048] Preparation of modified graphene oxide:

[0049] S1. In a three-necked flask equipped with a stirring device, 32.2 g of tris(hydroxymethyl)aminomethane hydrochloride, 30 mL of triethylamine and 200 mL of N,N-dimethylformamide were mixed at room temperature, placed in an ice-water bath at 3°C, and stirred for 30 min. Then, 30.6 g of phosphorus oxychloride was slowly added dropwise, and the temperature was controlled not to exceed 20°C during the addition. After the addition was completed, the temperature was raised to 85°C and kept for reaction for 7 h. After the reaction was completed, the solvent was removed by filtration under reduced pressure, and the filter cake was washed 3 times with anhydrous ethanol and dried in vacuo to obtain intermediate 1.

[0050] S2. Under nitrogen protection at room temperature, add 64.8 g of 4,4'-sulfonyldibenzoic acid and 300 mL of toluene to a three-necked flask equipped with a stirring device, heat to 35°C and stir continuously, add 33.0 g of intermediate 1 and 41.2 g of dicyclohexylcarbodiimide, mix and stir evenly, control the reaction temperature to 55°C, keep the temperature for 2 hours, filter after the reaction, remove the solvent by vacuum distillation, wash twice with anhydrous ethanol, and vacuum dry to obtain intermediate 2;

[0051] S3, in a three-necked flask equipped with a stirring device, add 26.6g 3,5-diaminopyridine, 90.6g intermediate 2, 41.2g dicyclohexylcarbodiimide and 300mL N,N-dimethylformamide, stir and mix well, place in a 60°C water bath, heat in a water bath for 5h, filter after the reaction, remove the solvent by vacuum distillation, and purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, the volume ratio of the two is 2:3), and remove the eluent by rotary evaporation to obtain intermediate 3;

[0052] S4. In a three-necked flask equipped with a stirring device, 12.8 g of intermediate 3 was mixed with 200 mL of N, N-dimethylformamide, and 4.6 g of dicyclohexylcarbodiimide was added and stirred evenly; then 200 mL of graphene oxide dispersion (DMF was used as a dispersion medium with a concentration of 10 mg / mL) was slowly added, stirring was performed while adding, ultrasonic treatment was performed for 15 min, heating was performed at 60° C., and the reaction was kept warm for 8 h, stirring was continued during the reaction, and the reaction was completed, vacuum distillation, ethyl acetate washing, and freeze-drying were performed to obtain pre-modified graphene oxide;

[0053] S5. Add 2 g of pre-modified graphene oxide and 200 mL of N,N-dimethylformamide to a three-necked flask equipped with a reflux device, and disperse them evenly by ultrasonication. Then slowly drop 13 mL of ethyl bromide. After the addition is complete, place the mixture in a water bath at 55°C and reflux for 6 hours. After the reaction is complete, evaporate under reduced pressure, wash with ethanol, and cool and dry to obtain modified graphene oxide.

[0054] Embodiment 3

[0055] Preparation of pre-treated PET recycled material:

[0056] 1 g of PET recycled material was added to a grinder and crushed, then added to 40 mL of water and stirred for 5 min. 2.4 g of sodium dodecyl sulfate was added and stirred for 30 min. The material was filtered and washed with water for 3 times. The material was dried in an oven at 100 °C for 2 h. The material was added to 20 mL of tetrahydrofuran and stirred for 30 min. The filter cake was washed with ethanol solution and dried in an oven at 80 °C for 1 h to obtain pretreated PET recycled material.

[0057] Embodiment 4

[0058] Preparation of pre-treated PET recycled material:

[0059] 2 g of PET recycled material was added to a grinder and crushed, then added to 80 mL of water, stirred for 5 min, 4.8 g of sodium dodecyl sulfate was added, stirring was continued for 30 min, filtered, washed with water 3 times, dried in an oven at 100 ° C for 2 h, added to 40 mL of tetrahydrofuran, stirred for 30 min, filtered, the filter cake was washed with ethanol solution, and dried in an oven at 80 ° C for 1 h to obtain pretreated PET recycled material.

[0060] Embodiment 5

[0061] 70 g of the pretreated PET recycled material prepared in Example 3, 8 g of the modified graphene oxide prepared in Example 1, 3 g of antioxidant (2 g of antioxidant 1010 and 1 g of BASF antioxidant PS800) and 3 g of paraffin were mixed and added to a twin-screw extruder, melt blended, extruded and granulated to obtain modified PET recycled material.

[0062] Embodiment 6

[0063] 80 g of the pretreated PET recycled material prepared in Example 4, 16 g of the modified graphene oxide prepared in Example 2, 6 g of antioxidant (4 g of antioxidant 1010 and 2 g of BASF antioxidant PS800) and 4 g of stearamide fatty acid were mixed and added to a twin-screw extruder, melt blended, extruded and granulated to obtain modified PET recycled material.

[0064] Embodiment 7

[0065] 90 g of the pretreated PET recycled material prepared in Example 4, 24 g of the modified graphene oxide prepared in Example 2, 9 g of antioxidant (6 g of antioxidant 1010 and 3 g of BASF antioxidant PS800) and 5 g of stearamide fatty acid were mixed and added to a twin-screw extruder, melt blended, extruded and granulated to obtain modified PET recycled material.

[0066] Comparative Example 1

[0067] Ordinary graphene oxide of equal mass was used to replace the modified graphene oxide in Example 7, and the remaining steps were the same as those in Example 7.

[0068] Comparative Example 2

[0069] Commercially available recycled PET was used.

[0070] Embodiments 5, 6, 7 and comparative examples 1 and 2 were made into corresponding shapes according to different test standards and subjected to the following performance tests:

[0071] The tensile strength was determined using the national standard GB / T 1040-2006 "Determination of tensile properties of plastics";

[0072] The sample was placed in an environment of 150°C and oxidized with hot air for 72 hours, and then the tensile strength was measured (test standard GB / T1040.2-2006), and the retention rate of tensile strength was calculated; the retention rate of tensile strength = tensile strength after test / tensile strength before test × 100%;

[0073] The oxidation induction time was determined using the national standard GB / T 19466.6-2009 "Plastic Differential Scanning Calorimetry";

[0074] The antibacterial rate of Staphylococcus aureus and Escherichia coli in the sample was determined using QB / T 2591-2003A "Test methods and antibacterial effects of antibacterial plastics";

[0075] The limiting oxygen index of Examples 5, 6, and 7 before and after 180 days was determined using the national standard GB / T 2406-2008 "Test Method for Combustion Performance of Plastics";

[0076] The measured results are shown in the following table:

[0077]

[0078]

[0079] Therefore, the flame retardancy, antibacterial and heat resistance of the PET recycled material prepared in the embodiment of the present invention are higher than those of the comparative example, and the antioxidant performance is good and the performance is long-term and stable, which has important application value in the field of plastic recycling technology.

[0080] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0081] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing modified PET recycled material, characterized in that: The following steps are involved: The pretreated PET recycled material, modified graphene oxide, antioxidant and lubricant are mixed and added into a twin-screw extruder, melt-blended, extruded and granulated to obtain the modified PET recycled material.

2. The method for preparing a modified PET recycled material according to claim 1, characterized in that: The modified graphene oxide is prepared by the following steps: S1. Mix tris(hydroxymethyl)aminomethane hydrochloride, triethylamine and N,N-dimethylformamide, place in an ice-water bath at 3°C, stir thoroughly for 30 minutes, then drop phosphorus oxychloride, add dropwise until the addition is complete, react at 85°C for 7 hours, and after the reaction is complete, filter under reduced pressure, wash, and dry in vacuo to obtain intermediate 1; S2. Under nitrogen protection, 4,4'-sulfonyldibenzoic acid and toluene were mixed, heated to 35°C and stirred continuously, intermediate 1 and dicyclohexylcarbodiimide were added, mixed and stirred evenly, and reacted at 55°C for 2h. After the reaction was completed, the mixture was filtered, distilled under reduced pressure, washed, and dried in vacuo to obtain intermediate 2; S3, 3,5-diaminopyridine, intermediate 2, dicyclohexylcarbodiimide and N,N-dimethylformamide were stirred and mixed evenly, and then placed in a 60°C water bath and heated in the water bath for 5 hours. After the reaction was completed, the mixture was filtered, vacuum distilled, purified by column chromatography, and rotary evaporated to obtain intermediate 3; S4, after mixing the intermediate 3 with N,N-dimethylformamide, add dicyclohexylcarbodiimide and stir evenly; then slowly add the graphene oxide dispersion, stirring while adding, ultrasonic treatment for 15 minutes, heating to 60°C, keeping the temperature for reaction for 8 hours, stirring continuously during the reaction, and after the reaction is completed, vacuum distillation, washing, and freeze drying are performed to obtain pre-modified graphene oxide; S5. After the pre-modified graphene oxide and N,N-dimethylformamide are uniformly dispersed by ultrasonication, ethyl bromide is slowly added dropwise. After the addition is completed, the mixture is placed in a water bath at 55°C and refluxed for 6 hours. After the reaction is completed, the mixture is distilled under reduced pressure, washed, cooled and dried to obtain modified graphene oxide.

3. The method for preparing a modified PET recycled material according to claim 2, characterized in that: In step S1, the ratio of tris(hydroxymethyl)aminomethane hydrochloride, triethylamine, N,N-dimethylformamide, and phosphorus oxychloride is 16.1 g:15 mL:100 mL:15.3 g.

4. The method for preparing a modified PET recycled material according to claim 2, characterized in that: In step S2, the ratio of the amount of 4,4'-sulfonyldibenzoic acid, toluene, intermediate 1, and dicyclohexylcarbodiimide is 32.4 g: 150 mL: 16.5 g: 20.6 g.

5. The method for preparing a modified PET recycled material according to claim 2, characterized in that: In step S3, the ratio of the amount of 3,5-diaminopyridine, intermediate 2, dicyclohexylcarbodiimide, and N,N-dimethylformamide used is 13.3 g:45.3 g:20.6 g:150 mL.

6. The method for preparing a modified PET recycled material according to claim 2, characterized in that: In step S4, the ratio of the amount of intermediate 3, N,N-dimethylformamide, dicyclohexylcarbodiimide, and graphene oxide dispersion is 6.4 g:100 mL:2.3 g:100 mL.

7. The method for preparing a modified PET recycled material according to claim 2, characterized in that: In step S5, the ratio of the amount of pre-modified graphene oxide, N,N-dimethylformamide, and ethyl bromide is 1 g:100 mL:6.5 mL.

8. The method for preparing a modified PET recycled material according to claim 1, characterized in that: The pre-treated PET recycled material is prepared by the following steps: The PET recycled material is added to a pulverizer and crushed, then added to water, stirred, and then sodium dodecyl sulfate is added. The stirring is continued, filtered, washed with water for 3-4 times, and dried in an oven. The PET recycled material is then added to tetrahydrofuran, stirred, filtered, washed, and dried in an oven to obtain the pretreated PET recycled material.

9. The method for preparing a modified PET recycled material according to claim 1, characterized in that: The raw materials are calculated in parts by weight as follows: 70-90 parts of pre-treated PET recycled material, 8-24 parts of modified graphene oxide, 3-9 parts of antioxidant, and 3-5 parts of lubricant.

10. A modified PET recycled material, characterized in that: Prepared according to the method according to any one of claims 1 to 9.

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