A method for preparing polyamide PA10T copolymer by using waste PET as raw material

Abstract

The application discloses a method for preparing polyamide PA10T copolymer by taking waste PET as raw material, and comprises the following steps: 1) pretreatment: the collected waste PET is crushed by a crusher, washed and dried; 2) the pretreated PET, decamethylenediamine, water and a complexing agent are mixed in proportion; 3) under the protection of inert gas, the above-mentioned mixed system is heated to 200-230 DEG C, and after heat preservation and pressure preservation for 1-5 hours, the system is degassed to normal pressure, and then vacuumized to discharge, so that the PA10T copolymer product is obtained. The application takes waste PET as raw material, and uses water to replace traditional organic solvent, so that white pollution can be reduced, resources and raw materials can be greatly saved, recycling and reuse of waste plastics are realized, high recycling cost and harm to human body in recycling of the organic solvent are avoided. Meanwhile, the obtained PA10T copolymer product retains part of polyester segments, so that the product still has good heat resistance.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a method for preparing polyamide PA10T copolymer using waste PET as raw material. Background Technology

[0002] Polyethylene terephthalate (PET) is lightweight, impact-resistant, and possesses excellent mechanical and processing properties, making it widely applicable in plastics, fibers, and other fields. Statistics show that China's demand for PET fiber in 2022 was approximately 57.027 million tons. Currently, over 90% of TPA (treasure terephthalate) from petroleum is used to produce PET, and the massive consumption of PET products not only causes white pollution but also exacerbates petroleum depletion. Therefore, developing efficient and economical recycling technologies for waste PET is of significant practical importance.

[0003] Generally, PET recycling is divided into three levels based on the different recycling processes. Level 1 recycling is physical recycling. This involves processing plastic products through steps such as crushing, washing, extrusion, and granulation. However, PET recycled using these two methods will have varying degrees of reduced performance in the products after reprocessing, significantly impacting their subsequent use. Level 2 recycling is chemical recycling, using chemical technologies to process waste plastics to obtain corresponding monomers or chemical raw materials. However, this process increases the cost of PET recycling, and the obtained monomers need further reaction to obtain the desired products. Level 3 recycling is energy recovery, burning waste plastics that cannot be further chemically recycled to obtain heat energy. However, the incineration process produces large amounts of harmful gases, impacting the environment.

[0004] In recent years, researchers have focused on the high-value recycling and utilization of PET. The preparation of polyamides through amidation reactions not only recycles waste PET but also directly transforms it into high-performance polyamide products, reducing recycling steps and lowering product costs, thus possessing significant potential for widespread application.

[0005] Patent CN 102604081 A discloses a method for synthesizing high-temperature resistant nylon using PET, resulting in a copolymer with a suitable melting point and good low-temperature impact strength. However, the solvents used in this reaction are organic solvents such as N-methylpyrrolidone and dimethylimide, which are costly, difficult to recycle efficiently, and cause significant pollution that is harmful to human health.

[0006] Zhang Ruiling used PET and hexamethylenediamine as raw materials, and Xu Xiaohui used PET and dodecanediamine as raw materials to prepare PA6T copolymers and PA12T copolymers, respectively. They explored the optimal process conditions for the amidation reaction and tested the performance of the products. However, in both experiments, the medium for the amidation reaction was still the organic solvent sulfolane, which is costly, toxic, and environmentally polluting, and its recovery process is cumbersome, making it unsuitable for large-scale industrial use.

[0007] Patent CN 102816325 A discloses a method for preparing a high-temperature resistant nylon / PBT / PET copolymer. It mainly explores the properties of copolymers of different proportions of high-temperature resistant nylon and PBT, and points out that the introduction of PBT improves the barrier properties and heat resistance of the material. The solvents used in this synthesis process are N-methylpyrrolidone, sulfolane, or tetramethyl sulfone, and the subsequent processing of the product, including solvent recovery, is relatively difficult.

[0008] Patent CN102634012A discloses a high-temperature resistant nylon / PEN / PET copolymer, its preparation method, and its applications. This copolymer consists of 75-99% high-temperature nylon, 0.85-23.75% PEN, and 0.05-3.75% PET by mass. The high-temperature nylon is a high-temperature nylon unit formed by reacting PEN, PET, and a diamine. The diamine is a straight-chain aliphatic diamine, a branched-chain aliphatic diamine, or an alicyclic diamine. The solvent used in this process is N-methylpyrrolidone, which has a high cost.

[0009] Patent CN117777436A discloses a method for preparing PA6T copolymers using PET and hexamethylenediamine as raw materials. This experiment is the first to use water as the reaction medium instead of traditional organic solvents, which reduces costs and pollution, and also effectively lowers the cost of solvent recovery, providing a new approach for the amidation reaction of PET. However, the two-step method used in the experiment has high energy consumption and low efficiency, and cross-linking easily occurs when the temperature is raised to a higher level. Summary of the Invention

[0010] The purpose of this invention is to provide a new method for preparing polyamide PA10T copolymer using waste PET as raw material.

[0011] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0012] A novel method for preparing polyamide PA10T copolymer from waste PET includes the following steps:

[0013] 1) Pretreatment: The collected waste PET is crushed into thin sheets with a diameter of 1-2 cm using a shredder, washed with distilled water to remove impurities, and dried at room temperature;

[0014] 2) Mix the pretreated PET, decanediamine, water, and complexing agent in the specified proportions;

[0015] 3) Under inert gas protection, the above mixture is heated to 200-230℃, kept at the temperature and pressure for 1-5 hours, then the gas is released to normal pressure, and then vacuumed before discharge to obtain PA10T copolymer product.

[0016] In step 3), the reason for controlling the system temperature to be 200-230℃ is that if the reaction temperature is too low, the activation energy provided during the reaction process will be low, and the rate of hydrolysis and aminolysis of PET will be slow; when the reaction temperature is too high, cross-linking is very likely to occur during the polymerization process. Therefore, controlling the temperature of the system in this invention to be 200-230℃ is crucial.

[0017] As a further preferred embodiment of the present invention, in step 2), the complexing agent is one or a mixture of two or more of sodium tripolyphosphate, triethanolamine, EDTA, DTPA, and HPMA, and the amount of complexing agent is 0.1-0.3‰ of the total mass of PET and decanediamine.

[0018] As a further preferred embodiment of the present invention, the complexing agent is EDTA.

[0019] As a further preferred embodiment of the present invention, in step 1), the molar ratio of the decanediamine to the waste PET repeating unit is (0.6-1):1.

[0020] As a further preferred embodiment of the present invention, in step 1), the mass ratio of water to the total mass of PET and decanediamine is (0.6-2):1. Experiments show that while a larger volume of water is beneficial for mass transfer, it may also reduce the concentration of the reaction system and slow down the reaction rate; conversely, a smaller volume of water may lead to excessively high local concentrations, triggering side reactions or uneven reactions. Therefore, controlling the appropriate water volume (0.6-2):1 in the system of the present invention is crucial for the amidation reaction.

[0021] As a further preferred embodiment of the present invention, in step 2), the heat preservation and pressure holding time is 1-5 hours, preferably 1-3 hours; the gas release time is 1.5-2.5 hours. Maintaining a constant temperature for a period of time in this step directly affects the molecular chain growth rate and the degree of reaction. In the aqueous system, the high specific heat capacity of water can stabilize the reaction temperature and avoid side reactions (such as hydrolysis or degradation) caused by local overheating. If the gas release time is too short, it may lead to the residue of by-products; if the gas release time is too long, it will cause energy waste. Therefore, it is necessary to investigate different gas release time conditions, and finally determine that the heat preservation and pressure holding time is 1-5 hours, preferably 1-3 hours; and the gas release time is 1.5-2.5 hours.

[0022] As a further preferred embodiment of the present invention, in step 2), the atmospheric pressure time is 1.5-3 hours.

[0023] As a further preferred embodiment of the present invention, in step 2), the vacuuming time is 2-6 hours, preferably 3-5 hours.

[0024] As a further preferred embodiment of the present invention, in step 2), the inert gas is nitrogen.

[0025] This invention involves heating the reaction system to a preset temperature range of 200-230℃, maintaining this temperature at the target level for a certain period, then releasing the pressure gradient within the reactor to atmospheric pressure and holding this pressure for a period to remove byproducts. A vacuum system is then activated to evacuate the reactor to a vacuum level and maintain this for a period. Heating is then turned off, maintaining the vacuum state, and the mixture is allowed to cool to room temperature before being discharged to obtain the final PA10T copolymer. The atmospheric pressure stage aims to reduce the defect rate by stabilizing melt flow and promoting residual monomer reaction, while the vacuum stage utilizes negative pressure to efficiently remove low-molecular-weight byproducts, thereby increasing molecular weight and purity. By controlling the conditions of both stages, this invention yields a high-molecular-weight PA10T copolymer.

[0026] The main innovation of this invention lies in the one-step preparation of PA10T using the amidation reaction of polyester, which solves the problem of crosslinking reaction that occurs at elevated temperatures. This not only opens up new avenues for the efficient recycling of PET polyester, but also, compared to using organic solvents for the amidation reaction, the use of water as the reaction medium significantly reduces costs and aligns better with the concept of green development.

[0027] In this invention, water is used as the dispersion medium, and its effects are mainly reflected in the following aspects: first, it promotes the breaking of ester bonds in PET; second, it provides a favorable reaction environment for the amidation reaction, which is conducive to the attack of nitrogen atoms on amino groups on carbon atoms on ester bonds, thereby improving the efficiency of the reaction.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) In the synthesis of high-temperature resistant nylon, this invention employs a novel green synthetic route for amidation reaction using an aqueous dispersion system, which exhibits significant advantages compared to the use of organic solvents. This technology achieves precise control of molecular chain structure by using water as the reaction medium. At the same time, relying on azeotropic dehydration of the solution, low-molecular-weight byproducts in the reaction system can be efficiently removed, resulting in products with better color and purity, and polymers with superior performance.

[0030] 2) Regarding the recycling of polyester, this invention realizes the high-value utilization of waste plastics and provides a solution for the green and efficient recycling of PET that combines technological innovation and commercial feasibility.

[0031] 3) The preparation method of the present invention is simple, saves time and economic costs, and is suitable for industrial promotion. Attached Figure Description

[0032] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 The image shows the FT-IR spectrum of the PA10T copolymer obtained in Example 1.

[0034] Figure 2 The image shows the gas chromatography-mass spectrometry (GC-MS) spectrum of the ethylene glycol content in the filtrate after solvent washing of the PA10T copolymer obtained in Example 1.

[0035] Figure 3 The image shows the DSC curve of the PA10T copolymer obtained in Example 1. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below in conjunction with specific embodiments. However, the following embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] Example 1

[0038] A method for preparing polyamide PA10T copolymer from waste PET includes the following steps:

[0039] 1) Pretreatment: The collected waste PET is crushed into thin sheets with a diameter of 1-2 cm using a shredder, washed with distilled water to remove impurities, and dried at room temperature;

[0040] 2) Weigh out 105.4g of treated waste PET, 94.6g of decanediamine, 400g of deionized water, and 0.04g of complexing agent EDTA. Mix them thoroughly and add them to the polymerization reactor, then seal it. Replace the gas three times. The specific steps are as follows: First, introduce nitrogen gas to bring the pressure inside the reactor to 0.2MPa, then release the gas to atmospheric pressure, and then evacuate to a negative pressure state. Repeat this replacement operation three times. Then, refill with nitrogen gas. After the pressure drops to atmospheric pressure, close the inlet valve to complete the gas replacement. 3) Turn on the heating device and heat the reaction system to 210℃. Maintain this temperature for 2 hours, then release the pressure inside the polymerization reactor to 0MPa within 1.5 hours and maintain this pressure for 2 hours. Start the vacuum system to evacuate the reactor to a vacuum state and maintain this vacuum for 4 hours. Turn off the heating, maintain the vacuum state, and allow it to cool to room temperature. Discharge the material to obtain the final PA10T copolymer.

[0041] Example 2

[0042] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the molar ratio of decanediamine to PET is 0.8:1.

[0043] Example 3

[0044] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the molar ratio of decanediamine to PET is 0.6:1.

[0045] Example 4

[0046] This embodiment uses waste PET as raw material to prepare polyamide PA10T copolymer. The difference between this embodiment and Example 1 is that the complexing agent in this embodiment is sodium tripolyphosphate, while the rest is the same as in Example 1.

[0047] Example 5

[0048] This embodiment uses waste PET as raw material to prepare polyamide PA10T copolymer. The difference between this embodiment and Example 1 is that the complexing agent in this embodiment is triethanolamine, while the rest is the same as in Example 1.

[0049] Example 6

[0050] This embodiment uses waste PET as raw material to prepare polyamide PA10T copolymer. The difference between this embodiment and Example 1 is that the complexing agent in this embodiment is a mixture of EDTA and triethanolamine in a mass ratio of 1:1. The rest is the same as in Example 1.

[0051] Example 7

[0052] This embodiment uses waste PET as raw material to prepare polyamide PA10T copolymer. The difference between this embodiment and Example 1 is that the mass of water in this embodiment is 120g, while the rest is the same as in Example 1.

[0053] Example 8

[0054] This embodiment uses waste PET as raw material to prepare polyamide PA10T copolymer. The difference between this embodiment and Example 1 is that the mass of water in this embodiment is 140g, while the rest is the same as in Example 1.

[0055] Example 9

[0056] This embodiment uses waste PET as raw material to prepare polyamide PA10T copolymer. The difference between this embodiment and Example 1 is that the mass of water in this embodiment is 160g, while the rest is the same as in Example 1.

[0057] Example 10

[0058] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the heat preservation temperature in this embodiment is 200℃, while the rest is the same as in Example 1.

[0059] Example 11

[0060] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the heat preservation temperature in this embodiment is 220℃, while the rest is the same as in Example 1.

[0061] Example 12

[0062] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the heat preservation temperature in this embodiment is 230℃, while the rest is the same as in Example 1.

[0063] Example 13

[0064] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the heat preservation time in this embodiment is 1 hour, while the rest is the same as in Example 1.

[0065] Example 14

[0066] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the heat preservation time in this embodiment is 3 hours, while the rest is the same as in Example 1.

[0067] Example 15

[0068] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the venting time in this embodiment is 1 hour, while the rest is the same as in Example 1.

[0069] Example 16

[0070] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the venting time in this embodiment is 2 hours, while the rest is the same as in Example 1.

[0071] Example 17

[0072] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the venting time in this embodiment is 2.5 hours, while the rest is the same as in Example 1.

[0073] Example 18:

[0074] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the atmospheric pressure time in this embodiment is 1.5 hours, while the rest is the same as in Example 1.

[0075] Example 19

[0076] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the atmospheric pressure time in this embodiment is 2.5 hours, while the rest is the same as in Example 1.

[0077] Example 20

[0078] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the atmospheric pressure time in this embodiment is 3 hours, while the rest is the same as in Example 1.

[0079] Example 21

[0080] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the vacuuming time in this embodiment is 3 hours, while the rest is the same as in Example 1.

[0081] Example 22

[0082] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the vacuuming time in this embodiment is 5 hours, while the rest is the same as in Example 1.

[0083] Example 23

[0084] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the amount of complexing agent added in this embodiment is 0.1‰, while the rest is the same as in Example 1.

[0085] Example 24

[0086] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this embodiment differs from that in Example 1 in that the amount of complexing agent added in this embodiment is 0.3‰, while the rest is the same as in Example 1.

[0087] Comparative Example 1

[0088] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this comparative example differs from that in Example 1 in that the vacuuming time in this example is 2 hours, while the rest is the same as in Example 1.

[0089] Comparative Example 2

[0090] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this comparative example differs from that in Example 1 in that the vacuuming time in this example is 6 hours, while the rest is the same as in Example 1.

[0091] Comparative Example 3

[0092] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this comparative example differs from that in Example 1 in that the heat preservation temperature in this example is 190°C, while the rest is the same as in Example 1.

[0093] Comparative Example 4

[0094] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this comparative example differs from that in Example 1 in that the heat preservation temperature in this example is 240℃, while the rest is the same as in Example 1.

[0095] Comparative Example 5

[0096] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this comparative example differs from that in Example 11 in that the amount of complexing agent added in this example is 0g, while the rest is the same as in Example 11.

[0097] Comparative Example 6

[0098] The method for preparing polyamide PA10T copolymer using waste PET as raw material in this comparative example differs from that in Example 11 in that the amount of complexing agent added in this example is 0.08g, while the rest is the same as in Example 11.

[0099] Test results

[0100] To illustrate the effectiveness of this invention, this test uses the product of Example 1 as an example and provides specific experimental results. The amidated product prepared in Example 1 was characterized by Fourier Transform Infrared Spectroscopy (FTIR) for molecular structure analysis, by Differential Scanning Calorimetry (DSC) for melting point characterization, and by Gas Chromatography-Mass Spectrometry (GC-MS) for quantitative measurement of the amount of ethylene glycol displaced to calculate the conversion rate. The results are as follows: Figure 1 , Figure 2 , Figure 3 As shown.

[0101] Figure 1 The diagram shows some characteristic groups and corresponding peak positions of the PA10T copolymer. The results show that the PA10T copolymer was successfully prepared using the method of the present invention.

[0102] Figure 2 The content of ethylene glycol displaced in the product is quantitatively calculated by integrating the peak area of ​​ethylene glycol. Figure 3 The second heating curve of the amidated product prepared in Example 1 when the melting point was measured by differential scanning calorimetry.

[0103] The physical properties of the amidated products synthesized under different conditions were also characterized in this invention. The instruments and testing standards used for characterization are as follows:

[0104] Table 1 Test Items, Instruments and Standards

[0105] Test Project Testing instruments Test Standards Melting point DSC (PE-8500) 10℃ / min Viscosity Ubbelohde viscometer (0.9-1.0) GB / T 10247-2008 Conversion rate Gas Chromatography-Mass Spectrometry /

[0106] Amide reaction can displace ethylene glycol from polyester. The conversion rate is calculated by quantitatively measuring the actual amount of ethylene glycol displaced and comparing it with the theoretical yield of displaced ethylene glycol.

[0107]

[0108] Examples 1-3 reflect the effect of the molar ratio of raw material decanediamine to PET on the physical properties of PA10T copolymer. The test results are shown in Table 2.

[0109] Table 2. Properties of PA10T copolymers obtained in Examples 1-3

[0110] project Example 1 Example 2 Example 3 Mole ratio 1：1 0.8：1 0.6：1 Melting point (°C) 298 295 291 Viscosity 1.43 1.37 1.29 Conversion rate (%) 80.2 78.4 72.3

[0111] According to the data analysis in Table 2, as the molar ratio of sebacic acid to PET gradually increases, the melting point, viscosity and conversion rate of the copolymer gradually increase.

[0112] Examples 1 and 4-6 reflect the effect of changes in the type of complexing agent on the physical properties of PA10T copolymer. The specific results are shown in Table 3.

[0113] Table 3. Properties of PA10T copolymers obtained in Examples 1, 4-6

[0114]

[0115] As can be seen from Table 3, when the product reacts at 210℃, different types of complexing agents have different effects on the melting point, viscosity and conversion rate of the product. When EDTA is added as the complexing agent, the effect is the best.

[0116] Examples 1, 7-9 reflect the effect of water dosage on the physical properties of PA10T copolymer. The specific implementation results are shown in Table 4.

[0117] Table 4. Properties of PA10T copolymers obtained in Examples 1 and 7-9

[0118] project Example 1 Example 7 Example 8 Example 9 Water usage (g) 400 120 140 160 Melting point (°C) 298 297 296 295 Viscosity 1.43 1.52 1.46 1.43 Conversion rate (%) 80.2 86.4 83.2 82.1

[0119] As can be seen from Table 4, with the increase of water usage, the melting point, viscosity and conversion rate of the product gradually decrease, and the trend of change is relatively slow.

[0120] Examples 1, 10-12 reflect the effect of polymerization temperature on the physical properties of PA10T copolymer. The specific results are shown in Table 5.

[0121] Table 5. Properties of PA10T copolymers obtained in Examples 1, 10-12

[0122] project Example 1 Example 10 Example 11 Example 12 Insulation temperature (°C) 210 200 220 230 Melting point (°C) 298 296 297 298 Viscosity 1.43 1.42 1.45 Crosslinking Conversion rate (%) 80.2 78.4 80.2 80.2

[0123] As shown in Table 5, when the holding temperature increases from 200℃ to 210℃, the melting point and viscosity of the product remain basically unchanged, while the conversion rate increases; when the holding temperature increases from 210℃ to 230℃, the melting point and conversion rate of the product do not change significantly. Cross-linking occurs at 230℃.

[0124] Examples 1, 13, and 14 reflect the effect of changes in heat preservation time on the physical properties of PA10T copolymer. The specific implementation results are shown in Table 6.

[0125] Table 6. Properties of PA10T copolymers obtained in Examples 1, 13, and 14

[0126] project Example 1 Example 13 Example 14 Insulation time (h) 2 1 3 Melting point (°C) 298 295 296 Viscosity 1.43 1.39 1.42 Conversion rate (%) 80.2 80.0 81.2

[0127] As can be seen from Table 6, extending the heat preservation time has little effect on the melting point, viscosity and conversion rate of the product.

[0128] Examples 1, 15-17 reflect the effect of changes in venting time on the properties of PA10T copolymer. The specific results are shown in Table 7.

[0129] Table 7. Properties of PA10T copolymers obtained in Examples 1, 15-17

[0130] project Example 1 Example 15 Example 16 Example 17 Degassing time (h) 1.5 1 2 2.5 Melting point (°C) 298 291 297 298 Viscosity 1.53 1.40 1.53 1.56 Conversion rate (%) 80.2 80.4 80.2 80.1

[0131] As can be seen from Table 7, as the venting time increases, the melting point and conversion rate of the product remain basically unchanged, but the viscosity first increases and then tends to stabilize.

[0132] Examples 1, 18-20 reflect the effect of changes in atmospheric pressure and time on the physical properties of PA10T copolymer. The specific implementation results are shown in Table 8.

[0133] Table 8. Properties of PA10T copolymers obtained in Examples 1 and 18-20

[0134] project Example 1 Example 18 Example 19 Example 20 Time at atmospheric pressure (h) 2 1.5 2.5 3 Melting point (°C) 298 297 296 298 Viscosity 1.75 1.71 1.81 1.82 Conversion rate (%) 80.2 80.4 80.2 80.1

[0135] As can be seen from Table 8, the relative viscosity of the product gradually increases with the extension of atmospheric pressure time, while the melting point and conversion rate remain almost unchanged.

[0136] Examples 1, 21, and 22 reflect the effect of changes in vacuuming time on the properties of PA10T copolymers. The specific results are shown in Table 9.

[0137] Table 9. Properties of PA10T copolymers obtained in Examples 1, 21, and 22

[0138] project Example 1 Example 21 Example 22 Vacuuming time (h) 4 3 5 Melting point (°C) 298 296 298 Viscosity 2.48 2.33 2.50 Conversion rate (%) 80.2 80.2 80.1

[0139] As can be seen from Table 9, as the vacuuming time increases, the relative viscosity of the product gradually increases, while the melting point and conversion rate remain almost unchanged.

[0140] Examples 1, 23, and 24 reflect the effects of adding different amounts of complexing agent on the physical properties of PA10T copolymers. The specific implementation results are shown in Table 10.

[0141] Table 10 Properties of PA10T copolymers obtained in Examples 1, 23 and 24

[0142] project Example 1 Example 21 Example 22 Dosage of chelating agent (g) 0.04 0.02 0.06 Melting point (°C) 298 291 298 Viscosity 2.48 2.21 2.50 Conversion rate (%) 80.2 76.1 80.1

[0143] As can be seen from Table 10, the relative viscosity and melting point of the product increase with the increase of complexing agent content. After the complexation reaction is completed, the amount of complexing agent increases, but the relative viscosity and melting point remain unchanged.

[0144] The PA10T copolymers obtained from Comparative Example 1 and Comparative Example 2 were characterized, and the product characterization results are shown in Table 11.

[0145] Table 11. Properties of PA10T copolymers obtained in Example 1, Comparative Example 1, and Comparative Example 2

[0146] project Example 1 Comparative Example 1 Comparative Example 2 Vacuuming time (h) 4 2 6 Melting point (°C) 298 297 298 Viscosity 2.48 1.70 2.51 Conversion rate (%) 80.2 76.4 80.2

[0147] As can be seen from Table 11, in the initial stage of vacuuming, the viscosity hardly changed, or even decreased slightly or remained the same. After 4 hours, the viscosity increased significantly, and after 6 hours, the viscosity change became gradual again.

[0148] The PA10T copolymers obtained from Comparative Examples 3 and 4 were characterized, and the characterization results are shown in Table 12.

[0149] Table 12 Properties of PA10T copolymers obtained in Example 1, Comparative Example 3, and Comparative Example 4

[0150] project Example 1 Comparative Example 3 Comparative Example 4 Insulation temperature (°C) 210 190 240 Melting point (°C) 298 293 298 Viscosity 1.43 1.27 Crosslinking Conversion rate (%) 80.2 74.9 80.9

[0151] As can be seen from Table 12, the viscosity and melting point are both low when the temperature is 190℃. When the temperature reaches 240℃, cross-linking occurs, but the melting point and conversion rate do not change much.

[0152] The PA10T copolymers obtained from Comparative Examples 5 and 6 were characterized, and the product characterization results are shown in Table 13.

[0153] Table 13 Properties of PA10T copolymers obtained in Example 11, Comparative Example 5 and Comparative Example 6

[0154] project Example 11 Comparative Example 5 Comparative Example 6 Dosage of chelating agent (g) 0.04 0 0.08 Melting point (°C) 297 287 298 Viscosity 1.45 Crosslinking 1.45 Conversion rate (%) 80.2 74.9 80.3

[0155] As can be seen from Table 13, cross-linking occurs without the addition of a complexing agent at a temperature of 220℃, but the cross-linking phenomenon disappears after the addition of a complexing agent.

Claims

1. A method for preparing polyamide PA10T copolymer using waste PET as raw material, characterized in that, Includes the following steps: 1) Pretreatment: After crushing and washing the collected waste PET, dry it at room temperature for later use; 2) Mix the pretreated PET with decanediamine, water, and complexing agent in a specific ratio; 3) Under inert gas protection, the above mixture is heated to 200-230℃, kept at the temperature and pressure for 1-5 hours, the gas is released to normal pressure, and then vacuumed to discharge the material to obtain PA10T copolymer product. In step 2), the complexing agent is one or a mixture of two or more of sodium tripolyphosphate, triethanolamine, EDTA, DTPA, and HPMA, and the amount of complexing agent used is 0.1-0.3‰ of the total mass of PET and decanediamine. The ratio of water to the total mass of PET and decanediamine is (0.6-2):1; In step 3), the vacuuming time is 3-5 hours, and the heat preservation temperature does not include 230℃.

2. The method for preparing polyamide PA10T copolymer from waste PET as raw material according to claim 1, characterized in that, In the pretreatment process, waste PET is crushed into thin sheets with a diameter of 1-2 cm using a shredder, and then washed with distilled water.

3. The method for preparing polyamide PA10T copolymer from waste PET as raw material according to claim 2, characterized in that, The complexing agent is EDTA.

4. The method for preparing polyamide PA10T copolymer from waste PET as raw material according to claim 1, characterized in that, In step 2), the molar ratio of the decanediamine to the waste PET repeating unit is (0.6-1):

1.

5. The method for preparing polyamide PA10T copolymer from waste PET as raw material according to claim 1, characterized in that, In step 3), the heat preservation and pressure holding time is 1-3 hours; the venting time is 1.5-2.5 hours.

6. The method for preparing polyamide PA10T copolymer from waste PET as raw material according to claim 1, characterized in that, In step 3), the atmospheric pressure time is 1.5-3 hours.

7. The method for preparing polyamide PA10T copolymer from waste PET as raw material according to claim 1, characterized in that, In step 3), the inert gas is nitrogen.

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