Degradable polyesteramide and preparation method thereof

Abstract

The invention relates to the technical field of high polymer material synthesis and modification. The invention relates to a polyester amide, in particular to a degradable polyester amide and a preparation method thereof. The structural general formula of the polyesteramide is shown in the specification; wherein the polyesteramide has an A-B fragment structure; m and n are respectively expressed by mass percent of the fragment A and the fragment B in the polyesteramide, m + n = 100%, and m = 10-50%; x represents a straight chain carbon number and is an integer selected from 2-10; the polyesteramide is formed by polycondensation of alcoholysis oligomer of nylon 6 and 1, 10-sebacic acid. The polyesteramide can maintain excellent mechanical properties such as mechanical strength, wear resistance and the like similar to nylon 6, and also has a controllable degradation characteristic in a seawater environment, so that the stable performance of the polyesteramide in a marine fishery service period is ensured, the polyesteramide can be degraded under a specific marine environment condition after being discarded, long-term residue is avoided, and the service life of the polyesteramide is prolonged. 'ghost fishing gear 'and micro-plastic pollution are reduced from the source, and green and sustainable development of marine fishery is promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer material synthesis and modification. More particularly, it relates to a degradable polyester amide and a preparation method thereof. BACKGROUND

[0002] As an important high polymer material, polyester amide (PEA) has both the degradability of polyester and the excellent mechanical properties, heat resistance and chemical stability of polyamide. Its molecular chain contains both easily hydrolyzable ester bonds and strong hydrogen-bonding amide bonds. By adjusting the ratio of soft segment (ester) to hard segment (amide), the degradation rate, mechanical strength, thermal properties, etc. of PEA can be effectively controlled. Therefore, PEA shows broad application prospects in the fields of biomedical materials, high-performance fibers and environmentally friendly plastics. Its greatest advantage is that it can make up for the shortcomings of traditional polyester materials in mechanical properties and traditional polyamide in biodegradability to some extent, providing an ideal molecular design platform for developing degradable materials with excellent comprehensive performance.

[0003] At present, the synthesis routes of polyester amide mainly include two types: one is through the polycondensation reaction of diacid (or its diester), diol and diamine; the other is through the ring-opening copolymerization of lactam, cyclic ester and other monomers. However, these methods generally have problems such as high cost of raw materials, large amount of catalyst, complex synthesis process (such as the need for high vacuum, harsh catalyst selection), high metal content of products, or unsustainable monomer sources, which limit their large-scale industrial production and market application. Using widely available and low-cost nylon 6 as a basic raw material, through chemical modification, the molecular chain of nylon 6 is “tailored” and degradable units are introduced to synthesize polyester amide, which not only provides a new path for the high-value conversion of nylon 6, but also has significant economic and strategic necessity. This route can effectively activate existing industrial assets and realize the upgrading from general engineering plastics to high-end degradable new materials.

[0004] Nylon 6 has been widely used in marine fisheries due to its excellent mechanical strength, wear resistance, chemical corrosion resistance and processing performance, such as fishing nets, fishing lines, ropes, culture rafts and so on. However, nylon 6 is extremely difficult to degrade in the natural environment, especially in seawater conditions. Lost or abandoned nylon fishing gear can last for hundreds of years in the ocean, continuously entangling marine organisms, destroying habitats, and entering the food chain by breaking into microplastics, posing a long-term and serious threat to the marine ecosystem. This not only causes serious environmental problems, but also leads to direct economic losses of fishery resources. Therefore, developing new materials that can replace traditional nylon 6 and degrade in specific marine environments with comparable mechanical properties has become an urgent need for the sustainable development of marine fisheries. Based on the above ideas for modifying nylon 6, a new polyester amide material that can be controllably degraded in seawater is designed and synthesized, which has extremely important environmental protection value and practical significance for direct application in fishing gear. SUMMARY

[0005] Based on the above problems, one object of the present application is to provide a degradable polyester amide.

[0006] Another object of the present application is to provide a preparation method for preparing the degradable polyester amide as described above.

[0007] To achieve the above first object, the present application adopts the following technical solutions: The present application discloses a degradable polyester amide, the structural general formula of which is: ; Among them, the polyester amide has A-B fragment structure; The A fragment is: ; The B fragment is: ; m and n respectively represent the mass percentage of the A fragment and the B fragment in the polyester amide, m+n=100%, m=10-50%; x represents the number of straight-chain carbons, which is selected from an integer from 2 to 10; The polyester amide is obtained by polycondensation of alcoholysis oligomers of nylon 6 and 1,10-decanedioic acid; The alcoholysis oligomers of nylon 6 are products obtained by alcoholysis reaction of nylon 6 under the action of dihydric alcohol and catalyst, and the molecular weight thereof is below 2000 g / mol.

[0008] The nylon 6 used in the present application is mainly derived from nylon waste such as pellets, fibers, films and powders, and is specifically derived from one or more of abandoned fishing nets, gears, ropes and nylon clothes.

[0009] Further, the number average molecular weight Mn of the polyester amide is >50000 g / mol, and the PDI is <2.5.

[0010] Further, the addition amount of the 1,10-decanedioic acid is 0.05-0.5 times the total mass of the alcoholysis oligomer of the nylon 6.

[0011] To achieve the above-mentioned second object, the application adopts the following technical scheme: The application discloses a preparation method of the polyester amide as described above, comprising the following steps: The waste nylon 6 raw material, dihydric alcohol and catalyst are uniformly mixed, alcoholysis reaction is carried out, and when the molecular weight of the oligomer intermediate obtained by the alcoholysis reaction is below 2000 g / mol, the alcoholysis reaction is stopped, then 1,10-decanedioic acid is added, and the polyester amide is obtained through a repolymerization process.

[0012] The degradable polyester amide new material synthesized by modifying the nylon 6 has many significant advantages. First, it uses the mature nylon 6 in China as a raw material, which is easy to obtain and low in cost, and can realize the extension and value-added of the industrial chain. Second, the route can precisely control the chemical structure of the obtained polyester amide through controllable depolymerization and reconstruction of the nylon 6 macromolecule, so as to realize the best balance between the degradation performance in seawater environment and the mechanical properties during service. In addition, the application can synergistically catalyze the alcoholysis and polycondensation two-step reactions by using a single catalyst system, which not only significantly simplifies the process flow and reduces the catalyst cost, but also helps to reduce the metal residues in the final product polyester amide, thereby improving the product purity. Finally, directly applying this new material to marine fishery equipment can realize the greenization of the whole life cycle of the fishery tools without significantly changing the existing processing and use habits, and provides an innovative solution with technical feasibility, economy and environmental friendliness for solving the marine plastic pollution.

[0013] Further, the dihydric alcohol is a linear hydroxyl-terminated dihydric alcohol, and is selected from one or more of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol and 1,10-decanediol; preferably, the dihydric alcohol is ethylene glycol.

[0014] Further, the catalyst mainly includes common alcoholysis catalysts such as homogeneous acid-base catalysts, metal-based catalysts, and polymer catalysts, including but not limited to one of p-toluenesulfonic acid, boron trifluoride, zinc chloride, zinc acetate, zirconium chloride, stannous chloride, monobutyl tin oxide, peroxymolybdate, ion exchange resin, polymer metal complex, ionic liquid, RuMo / TiO2, CaO / SBA-15, immobilized enzyme, germanium dioxide, antimony trioxide, antimony acetate, antimony ethylene glycol, tetrabutyl titanate, tetraisopropyl titanate, titanium-silicon composite catalyst, and titanium-alcohol complex catalyst. In order to achieve uniformity with the catalyst in the subsequent repolymerization process, the catalyst is preferably tetrabutyl titanate and / or tetraisopropyl titanate. Therefore, the catalyst selected in the present application can catalyze the alcoholysis of nylon 6 and can also be used in the subsequent repolymerization process. The subsequent repolymerization does not need to add catalysts.

[0015] Further, the amount of the catalyst is controlled at 0.2-2.0 wt% of the nylon 6 raw material; for example, the amount of the catalyst is controlled at 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.4 wt%, 1.6 wt%, 1.7 wt%, 2 wt%, etc. of the nylon 6 raw material.

[0016] Further, the mass ratio of the dihydric alcohol to the nylon 6 raw material is 20:1-1:5; preferably 10:1-1:3. If the ratio of the dihydric alcohol to the nylon 6 raw material is too low, the viscosity of the system will be too high, and if the ratio of the dihydric alcohol to the nylon 6 raw material is too high, the alcoholysis efficiency will be reduced.

[0017] Further, the temperature of the alcoholysis reaction is 150-230°C, preferably 180-200°C. The time of the alcoholysis reaction is 5-20 h, preferably 10-15 h. The purpose of alcoholysis is to alcoholize the long-chain nylon 6 into short-chain oligomers with terminal hydroxyl / amino groups, and the molecular weight is <2000 g / mol.

[0018] Further, the molar ratio of the 1,10-decanedioic acid to the dihydric alcohol is 5:1-1:10. For example, the molar ratio of the 1,10-decanedioic acid to the dihydric alcohol can be 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.

[0019] Further, the repolymerization comprises: First, the alcoholysis product and the 1,10-decanedioic acid are subjected to esterification at a certain temperature until the water output reaches more than 80% of the theoretical value, and then the temperature is raised to perform polycondensation under vacuum conditions, wherein the theoretical water output = 2 x the number of moles of 1,10-decanedioic acid.

[0020] Further, the temperature of the esterification reaction is 180-200℃, and the time of the esterification reaction is 1-3h. The whole esterification process is carried out under mechanical stirring at 100-300 rpm to prevent local overheating. Note that the esterification process is not vacuumed to prevent the loss of dihydric alcohol.

[0021] Further, the temperature of the polycondensation reaction is 230-240℃, and the time of the polycondensation reaction is 3-8h, at which time the melt viscosity can reach the target viscosity (Ubbelohde viscometer, η=2.0-2.8, 25℃, 90% formic acid aqueous solution). In actual preparation, as the polycondensation time proceeds, the continuous rise of the viscosity of the product can be obviously observed, and after the stirring torque reaches 30 N·m, the stirring is stopped, that is, it is considered that the polycondensation process has been completed.

[0022] Further, the vacuum degree of the polycondensation reaction is maintained at 20-200 Pa. Under this vacuum degree, it can be ensured that small molecule products are timely extracted and the molecular weight is increased.

[0023] The beneficial effects of the present application are as follows: (1) Realize the innovation of raw materials with low cost and high added value and green manufacturing The present application uses low-cost nylon 6 as raw material, and successfully synthesizes high-value degradable polyester amide (D-PEA) through an innovative chemical modification route. This route not only effectively activates existing industrial resources and provides a green and high-value upgrade path for the nylon 6 industry chain, but also overcomes the bottleneck of high raw material cost and complex process of traditional PEA synthesis method, and has significant economic benefits and industrialization advantages.

[0024] (2) Realize the unification of catalyst system and significant improvement of product purity In the synthesis process, the same catalyst is used to catalyze the alcoholysis and polycondensation processes simultaneously. This design not only greatly simplifies the production process, reduces the total amount of catalyst used and production cost, but also reduces the residual catalyst in the final product from the source, significantly improves the purity of the material, and provides quality assurance for the application of the product in high-end fields.

[0025] (3) Create an ideal material with excellent mechanical properties and controllable seawater degradability The polyester amide prepared by the present application successfully balances the contradiction between "use strength" and "waste degradation". It can maintain mechanical properties such as mechanical properties and wear resistance comparable to nylon 6 during service, meeting the harsh use requirements of marine fisheries; and after being discarded, it can be controllably degraded in seawater environment, fundamentally solving the problem of "ghost fishing gear" and microplastic pollution caused by long-term residual of traditional nylon fishing gear.

[0026] (4) Provide an effective solution to solve the problem of marine plastic pollution from the source, promote the sustainable development of the industry By directly applying the material to the manufacture of fishing nets, fishing lines, ropes and other marine fishing equipment, direct replacement of non-degradable nylon products can be achieved. This provides a new technical approach to curb marine plastic pollution from the source, with significant environmental and social benefits, and will effectively promote the development of green and sustainable marine fisheries. BRIEF DESCRIPTION OF DRAWINGS

[0027] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0028] Figure 1 The stress-strain curves and mechanical property data of the polyester amides prepared in Examples 1-6 are shown in Figure 6, wherein 1 H nuclear magnetic resonance spectrum.

[0029] Figure 2 The DSC cooling and heating curves of the polyester amides prepared in Examples 1-6 are shown in Figure 3, wherein Figure 2 In Figure 3, a is the first cooling DSC curve of PEA10-50, PEA10-60, PEA10-70, PEA10-80, PEA10-85 and PEA10-90, and b is the first heating DSC curve of PEA10-50, PEA10-60, PEA10-70, PEA10-80, PEA10-85 and PEA10-90.

[0030] Figure 3 The stress-strain curves and mechanical property data of the polyester amides prepared in Examples 1-6 are shown in Figure 6, wherein Figure 3 In Figure 6, a is the stress-strain curve, and b is the mechanical property data.

[0031] Figure 4 A comparison chart showing the degradation of the polyester amides prepared in Examples 1-6 and commercial degradable plastics in an enzymatic hydrolysis environment is shown in Figure 4. DETAILED DESCRIPTION

[0032] In order to more clearly illustrate the present application, the present application will be further described below in conjunction with the preferred embodiments. Those skilled in the art should understand that the specific description below is illustrative and not limiting, and should not limit the scope of protection of the present application.

[0033] Example 1 PEA10-50 This example provides a method for preparing a degradable polyester amide. The specific preparation process includes the following steps: Put 0.4 kg of nylon 6 waste plastic, 0.65 kg of 1,4-butanediol and 4.5 g of tetrabutyl titanate catalyst into a 5 L reaction kettle, heat to 180 ℃, and continuously mechanically stir at a speed of 300 rpm for alcoholysis for 10 h. After alcoholysis, 0.73 kg of 1,10-decanedioic acid is added for esterification at 180 ℃ for 2 h. It can be calculated that the water output has reached more than 80% of the theoretical value. After esterification, the temperature is raised to 230 ℃, vacuum polycondensation is started, and the vacuum degree is maintained at 20~200 Pa. With the progress of polycondensation time, the continuous rise of product viscosity can be obviously observed. After the stirrer torque reaches 30 N·m, stirring is stopped, vacuum is released, and the product is discharged, cooled, and pelletized to obtain a polyester amide, which is recorded as PEA10-50.

[0034] Example 2 PEA10-60 The example provides a preparation method of a degradable polyester amide. The specific preparation process includes the following steps: Put 0.6 kg of nylon 6 waste plastic, 0.98 kg of 1,4-butanediol and 4.5 g of tetrabutyl titanate catalyst into a 5 L reaction kettle, heat to 180 ℃, and continuously mechanically stir at a speed of 300 rpm for alcoholysis for 10 h. After alcoholysis, 0.73 kg of 1,10-decanedioic acid is added for esterification at 180 ℃ for 2 h. It can be calculated that the water output has reached more than 80% of the theoretical value. After esterification, the temperature is raised to 230 ℃, vacuum polycondensation is started, and the vacuum degree is maintained at 20~200 Pa. With the progress of polycondensation time, the continuous rise of product viscosity can be obviously observed. After the stirrer torque reaches 30 N·m, stirring is stopped, vacuum is released, and the product is discharged, cooled, and pelletized to obtain a polyester amide, which is recorded as PEA10-60.

[0035] Example 3 PEA10-70 The example provides a preparation method of a degradable polyester amide. The specific preparation process includes the following steps: Put 0.9 kg of nylon 6 waste plastic, 1.47 kg of 1,4-butanediol and 4.5 g of tetrabutyl titanate catalyst into a 5 L reaction kettle, heat to 180 °C, and continuously mechanically stir at a speed of 300 rpm, and alcoholysis for 10 h. After alcoholysis, 0.73 kg of 1,10-decanedioic acid is added and esterified at 180 °C for 2 h. It can be calculated that the water output has reached more than 80% of the theoretical value. After esterification, the temperature is raised to 230 °C, vacuum polycondensation is started, and the vacuum degree is maintained at 20~200 Pa. With the progress of polycondensation time, the continuous rise of product viscosity can be obviously observed. When the stir torque reaches 30 N·m, stop stirring, release vacuum, discharge, cool, and cut into granules to obtain a polyester amide, denoted as PEA10-70.

[0036] Example 4 PEA10-80 This example provides a method for preparing a degradable polyester amide. The specific preparation process includes the following steps: Put 1.35 kg of nylon 6 waste plastic, 2.2 kg of 1,4-butanediol and 4.5 g of tetrabutyl titanate catalyst into a 10 L reaction kettle, heat to 180 °C, and continuously mechanically stir at a speed of 300 rpm, and alcoholysis for 10 h. After alcoholysis, 0.73 kg of 1,10-decanedioic acid is added and esterified at 180 °C for 2 h. It can be calculated that the water output has reached more than 80% of the theoretical value. After esterification, the temperature is raised to 230 °C, vacuum polycondensation is started, and the vacuum degree is maintained at 20~200 Pa. With the progress of polycondensation time, the continuous rise of product viscosity can be obviously observed. When the stir torque reaches 30 N·m, stop stirring, release vacuum, discharge, cool, and cut into granules to obtain a polyester amide, denoted as PEA10-80.

[0037] Example 5 PEA10-85 This example provides a method for preparing a degradable polyester amide. The specific preparation process includes the following steps: Example 1

[0038] Example 6 PEA10-90 This example provides a method for preparing a degradable polyester amide. The specific preparation process includes the following steps: Example 1

[0039] Structure and property characterization of polyester amide 1) Nuclear magnetic resonance hydrogen spectrum (H NMR) characterization of polyester amide structure: 1 H NMR) characterization of polyester amide structure: The structure and composition of D-PEA were analyzed by a nuclear magnetic resonance spectrometer produced by Germany Bruker with a model of Avance-600, using deuterated trifluoroacetic acid (CF3COOD) as a solvent and TMS as an internal standard, Figure 1The NMR spectra of the polyesteramides prepared in Examples 1-6 show that the proton peaks at δ=4.16 ppm (a) and δ=3.46 ppm (b) correspond to the characteristic methylene groups of the butanediol unit (connecting the ester bond) and the caprolactam unit (connecting the amide bond), respectively; the signals at δ=2.63 (c) and 2.38 ppm (d) originate from the methylene groups adjacent to the ester and amide bonds in the sebacic acid or caprolactam units, respectively; in addition, the broad peak at δ=1.70 ppm (e) is attributed to the β-methylene group of all structural units, while the strong peak at δ=1.29 ppm (f) comes from the long-range methylene group in the molecular chain that is not affected by the functional groups.

[0040] 2) Gel permeation chromatography (GPC) characterization of the molecular weight and molecular weight distribution of polyesteramide: Gel permeation chromatography analysis showed that the number-average molecular weight (Mn) of the polyesteramides in Examples 1-5 was 51,000-62,000, and the molecular weight distribution was narrow (PDI = 1.2-1.8). The tests were performed using hexafluoroisopropanol as the mobile phase, at a flow rate of 0.3 mL / min and a column temperature of 40 °C.

[0041] 3) Differential scanning calorimetry (DSC) was used to characterize the thermal properties of polyesteramide. The thermal properties of polyesteramide were investigated using differential scanning calorimetry (DSC). Tests were conducted under a nitrogen atmosphere, with a temperature range of -50 to 250 °C and a heating / cooling rate of 10 °C / min. The results are as follows: Figure 2 As shown in Table 1.

[0042] Table 1 Summary of Thermal Properties of D-PEA

[0043] Crystallization behavior analysis: The first cooling curve shows that the crystallization temperature (T) of polyesteramide is... c The concentration of amide increased significantly with increasing amide content. Specifically, the concentrations were: 50% (7℃) → 60% (62℃) → 70% (102℃) → 80% (127℃) → 85% (143℃) → 90% (164℃). This trend is attributed to the increased intermolecular hydrogen bonds introduced by amides, which strengthens intermolecular forces, allowing the polymer to begin nucleation and crystallization earlier during cooling.

[0044] Thermal transition behavior analysis: The second heating curve reveals the effect of amide content on the glass transition temperature (T). g ) and melting temperature (T) m Similar effects to: glass transition temperature T mThe temperature systematically increases from -29 °C at 50% amide content to 28 °C at 90% amide content because hydrogen bonding increases the entanglement density of the molecular chains, requiring higher energy (temperature) for chain segments to begin moving. Melting temperature T m The temperature also increases due to the enhanced intermolecular forces, rising from 116 °C when the amide content is 50% to 201 °C when it is 90%.

[0045] Furthermore, the melting peak in the secondary heating curve exhibits a double-peak characteristic, suggesting that the polymer may have the potential to form two different crystal forms at different cooling rates.

[0046] 4) Characterization of the mechanical properties of polyesteramide Sample Preparation: Each polyesteramide sample was processed into standard dumbbell-shaped tensile specimens using an injection molding machine. The effective dimensions of the specimens were (25±1) mm × (4.0±0.4) mm × (2.0±0.2) mm, with a mass range of 1.5-2.0 g. The injection molding process parameters were as follows: injection temperature range of 180-255 ℃, mold temperature range of 30-110 ℃, injection time of 25 s, injection pressure of 500-800 bar, and holding time of 0 s. Testing Method: Mechanical property tests were conducted after the samples had been cured at room temperature for seven days. The tests were performed at a constant tensile rate of 100 mm / min at room temperature (25 ℃). To ensure data reliability, three parallel samples were tested for each condition, and the final results are given in the form of mean ± standard deviation.

[0047] Results and Discussion: Typical stress-strain curves and tensile properties of various polyesteramides are shown below. Figure 3 As shown in Table 2, the test results demonstrate that this series of polymers exhibits excellent comprehensive mechanical properties: their tensile strength ranges from 24 to 63 MPa, while their elongation at break is as high as 366-760%. This combination of high strength and high toughness indicates that polyesteramide has broad potential in engineering applications.

[0048] Table 2 Summary of Mechanical Properties of D-PEA

[0049] 5) Optical properties of polyesteramide To evaluate the optical properties of the material, the sample from Example 1 was cast into a thin film using a casting method and characterized using a haze meter according to standard methods. Test data showed that the transmittance of this series of samples was better than 91%, while the haze value was controlled below 16. This data indicates that the material allows most visible light to pass through while effectively controlling the cloud-like appearance caused by forward scattering of incident light, achieving an excellent balance between high transparency and low haze. Overall, this material exhibits superior optical performance; its high transmittance and low haze characteristics make it a promising candidate for applications in high-end packaging, optical displays, and protective coatings.

[0050] 6) Polyesteramide degradation performance test To assess the biodegradation potential of the materials, samples from Examples 1-6 were subjected to accelerated hydrolysis tests in a composite enzyme solution at 50 °C. This enzyme system simulated an active biodegradation environment and contained 5 mg / mL of *Thermophilus spp.* lipase (TL enzyme) and 1 mg / mL of *Aspergillus niger* and *Aspergillus oryzae* lipases. Figure 4 The weight loss data show that the D-PEA series materials exhibit significant mass loss during the 14-day degradation period, with the optimal component showing a weight loss rate as high as 33%. This degradation performance comprehensively surpasses that of common biodegradable polyester PBAT and is comparable to the degradation level of the current mainstream material PBS. The results indicate that while D-PEA maintains its mechanical properties by introducing amide bonds, its ester bonds can still be efficiently recognized and attacked by microbial lipases, demonstrating excellent enzymatic degradation sensitivity. This provides a crucial basis for its controlled degradation application under specific environments.

[0051] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A degradable polyesteramide characterized in that, The polyester amide has a general structure of: ； The polyester amide has an A-B segment structure; The A segment is: ； The B segment is: ； m and n respectively represent the mass percentage of the A segment and the B segment in the polyester amide, m+n=100%, m=10-50%; x represents a linear carbon number, and is an integer selected from 2-10; The polyester amide is obtained by oligomerization of alcoholysis of nylon 6 and polycondensation of 1,10-decanedioic acid. The alcoholysis oligomer of nylon 6 is a product obtained by alcoholysis reaction of nylon 6 under the action of a diol and a catalyst, and has a molecular weight below 2000 g / mol.

2. The polyester amide according to claim 1, characterized in that, The number average molecular weight Mn of the polyester amide is greater than 50000 g / mol, and the PDI is less than 2.

5.

3. The polyester amide according to claim 1, characterized in that, The addition amount of the 1,10-decanedioic acid is 0.05-0.5 times the total mass of the alcoholysis oligomer of nylon 6.

4. The process for the preparation of a polyester amide according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: The waste nylon 6 raw material, the diol and the catalyst are uniformly mixed to perform alcoholysis reaction, and when the molecular weight of the oligomer intermediate obtained by the alcoholysis reaction is below 2000 g / mol, the alcoholysis reaction is stopped, and then 1,10-decanedioic acid is added to obtain the polyester amide through a re-polymerization process.

5. The production method according to claim 4, characterized by, The diol is a linear hydroxyl diol, and is selected from one or more of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol and 1,10-decanediol. The catalyst is selected from one of p-toluenesulfonic acid, boron trifluoride, zinc chloride, zinc acetate, zirconium chloride, stannous chloride, monobutyl tin oxide, peroxymolybdate, ion exchange resin, high molecular metal complex, ionic liquid, RuMo / TiO2, CaO / SBA-15, immobilized enzyme, germanium dioxide, antimony trioxide, antimony acetate, ethylene glycol antimony, tetrabutyl titanate, tetraisopropyl titanate, titanium-silicon composite catalyst and titanium-alcohol complex catalyst.

6. The preparation method according to claim 4, characterized in that, The amount of the catalyst is controlled to be 0.2-2.0 wt% of the nylon 6 raw material. The mass ratio of the diol to the nylon 6 raw material is 20:1-1:

5. Preferably, the mass ratio of the diol to the nylon 6 raw material is 10:1-1:

3.

7. The preparation method according to claim 4, characterized in that, The temperature of the alcoholysis reaction is 150-230°C, and the time of the alcoholysis reaction is 5-20 h. Preferably, the temperature of the alcoholysis reaction is 180-200°C, and the time of the alcoholysis reaction is 10-15 h.

8. The preparation method according to claim 4, characterized in that, The molar ratio of the 1,10-decanedioic acid to the diol is 5:1-1:

10.

9. The preparation method according to claim 4, characterized in that, The re-polymerization comprises: First, the alcoholysis product and the 1,10-decanedioic acid are subjected to esterification reaction at a certain temperature until the water output reaches more than 80% of the theoretical value, and then the temperature is raised to perform polycondensation reaction under vacuum condition.

10. The method of claim 9, wherein, The temperature of the esterification reaction is 180-200°C, and the time of the esterification reaction is 1-3 h. The temperature of the polycondensation reaction is 230-240°C, and the time of the polycondensation reaction is 3-8 h, and the vacuum degree is maintained at 20-200 Pa.

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