Preparation method of biodegradable polyester fiber

Abstract

The invention belongs to the technical field of biodegradable polyester materials, and relates to a preparation method of biodegradable polyester fibers, which comprises the following steps: uniformly mixing a reaction type auxiliary agent and biodegradable polyester, carrying out melt spinning to obtain pre-oriented fibers, and carrying out hot drafting and heat setting on the pre-oriented fibers to obtain the biodegradable polyester fibers. The reaction type auxiliary agent is one or more of haplotype carbodiimide and polymeric carbodiimide; the mass ratio of the reaction type auxiliary agent to the biodegradable polyester is (0.5: 99.5)-(5.0: 95.0). According to the method, the crystallization temperature of the biodegradable polyester is increased, the adhesion between tows in the processing process of the biodegradable polyester fiber is avoided, the condition is mild, the operation is simple, and the method is suitable for large-scale industrial application.

Description

Technical Field

[0001] The invention belongs to the technical field of biodegradable polyester materials, and particularly relates to a method for preparing biodegradable polyester fibers. Background Art

[0002] Biodegradable polyester fiber not only has good mechanical properties, but is also an environmentally friendly material. It has been widely used in medical care, textiles and clothing, environmental governance and other fields. It is beneficial to environmental protection and sustainable development. It is of great value to study the preparation process of biodegradable polyester fiber.

[0003] During the melt extrusion process of biodegradable polyester fibers, thermal degradation reactions will occur in the biodegradable polyester, which will easily form molecular chain fragments of different molecular weights, lowering the crystallization temperature of the biodegradable polyester, thereby causing adhesion between the filament bundles of the biodegradable polyester fibers during thermal processing. Therefore, it is necessary to reduce the adhesion between the filament bundles of the biodegradable polyester fibers.

[0004] Literature (Preparation and performance study of thermoplastic starch blended modified PBAT fibers [J]. Synthetic Fiber Industry, 2023, 46(02): 1-7.) During the melt spinning of polybutylene adipate-butylene terephthalate (PBAT), TPS (thermoplastic starch) was introduced by a blending modification method to prepare PBAT / TPS blended slices and blended fibers. The added TPS can act as a crystallization nucleating agent in PBAT, thereby increasing the crystallization temperature and crystallization rate of PBAT. At the same time, the polyhydroxy structure of TPS can connect the molecular chains of PBAT, thereby improving the stability and spinnability of the PBAT melt to a certain extent.

[0005] However, thermoplastic starch is rich in hydroxyl groups and has strong polarity. It is not easy to mix completely with polyester materials when melted, which affects the melt fluidity and processability of polyester. Thermoplastic starch mainly connects the molecular chains of PBAT through hydrogen bonds. Hydrogen bonds are weaker than covalent bonds, and the connection effect on the PBAT molecular chains is not strong. The increase in the crystallization temperature of biodegradable polyester is limited, and there is still much room for improvement in the adhesion between filaments during thermal processing.

[0006] Therefore, it is necessary to develop a method for preparing biodegradable polyester fibers that can better avoid adhesion between tows during thermal processing. Summary of the invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for preparing biodegradable polyester fiber.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing biodegradable polyester fiber, comprising: uniformly mixing a reactive auxiliary agent and biodegradable polyester, melt spinning to obtain pre-oriented fibers, and then heat-stretching and heat-setting the pre-oriented fibers to obtain biodegradable polyester fibers;

[0010] The reactive auxiliary agent is one or more of monomeric carbodiimide and polymeric carbodiimide;

[0011] The mass ratio of the reactive auxiliary agent to the biodegradable polyester is 0.5:99.5-5.0:95.0.

[0012] The present invention solves the problem of adhesion between tows of biodegradable polyester fibers during processing by adding a specific type of reactive additive. The specific principle is as follows:

[0013] Biodegradable polyester is prone to form molecular chain fragments of different molecular weights during thermal processing. After the reactive additives are mixed with the biodegradable polyester, the reactive additives (monomeric carbodiimide, polymeric carbodiimide) will react with the end groups of the molecular chain fragments to form branched structures with different degrees of branching. The branched structures are evenly distributed in the melt, and the molecular chains are entangled to form physical entanglement points. The physical entanglement points, as "nucleation points" evenly distributed in the melt, can play a role similar to "nucleating agents" (i.e., heterogeneous nucleation), increase the crystallization temperature of biodegradable polyester, and thus avoid adhesion between the strands of biodegradable polyester fibers during processing. Thermal drawing of pre-oriented fibers can further improve the reaction of reactive additives with the end groups of the molecular chain fragments of biodegradable polyester, and further reduce the molecular weight distribution index of biodegradable polyester fibers.

[0014] In the prior art, polymeric carbodiimide is added during the processing of polymer materials, but the role of polymeric carbodiimide therein is different from that in the present invention;

[0015] For example, patent application CN102056992B aims to improve the hydrolysis resistance of flame retardant materials during use by adding polycarbodiimide during the preparation of thermoplastic flame retardant resins;

[0016] Patent application CN102834458B adds aliphatic and aromatic carbodiimide during the preparation of flame-retardant polylactic acid materials to improve the hydrolysis resistance of the polymer during processing and improve the compatibility of the flame retardant with the polymer;

[0017] Patent application CN102612540B adds carbodiimide compounds during the preparation of polybutylene terephthalate to improve hydrolysis resistance;

[0018] Patent application CN118007264A discloses a flame retardant polyester fiber and a preparation method thereof. After the flame retardant masterbatch and polyester are uniformly mixed, melt spinning is performed to obtain the flame retardant polyester fiber. The matrix of the flame retardant masterbatch is polypropylene, and polymeric carbodiimide and phosphorus flame retardant are uniformly dispersed in the polypropylene. Among them, the polymeric carbodiimide has many functions, and the function with the highest similarity to the present invention is that "the ester bond breakage in the polyester molecular chain occurs randomly, thereby forming molecular chain segments with carboxyl end groups and different molecular weights. The terminal carboxyl groups of the molecular chains of different chain lengths react with the polymeric carbodiimide and form ureide bonds to connect, so that the flame retardant polyester fiber retains the high strength of the long molecular chain segments, and also has the characteristics of being discontinuous. In addition, the terminal carboxyl groups of the molecular chains of different segment lengths react with the polymeric carbodiimide and form ureide bonds to form branched structures with different branch lengths. The branched molecular chains are more likely to entangle with each other, forming a physical cross-linked network and improving the mechanical properties. "It should be noted that although the effects are similar, they are not the same. In the patent application CN118007264A, the thermal degradation reaction of polyester during thermal processing is not violent. Therefore, although a branched structure is formed, the branched structure exists more at the interface between polyester and polypropylene, which plays a role in mechanical reinforcement and cannot form "nucleation points" evenly distributed in the melt, thereby failing to increase the crystallization temperature.

[0019] As the preferred technical solution:

[0020] According to the method for preparing a biodegradable polyester fiber as described above, the crystallization temperature of the biodegradable polyester fiber is 75-100° C., which is 30-60° C. higher than that of the biodegradable polyester fiber without adding a reactive additive.

[0021] In the method for preparing a biodegradable polyester fiber as described above, the molecular weight distribution index of the biodegradable polyester fiber is ≤2.

[0022] Mixing reactive additives with biodegradable polyester can also improve the melt stability and melt strength during the spinning process, thereby ensuring the stability and continuity of the biodegradable polyester during the spinning process. This is because: the reaction of the molecular chain fragment end groups produced by the reactive additives and the biodegradable polyester can inhibit the decrease in the molecular weight of the biodegradable polyester, control the molecular weight distribution of the biodegradable polyester within a narrow range, and the molecular weight distribution index is ≤2, thereby improving the melt stability and melt strength during the spinning process.

[0023] Although the reactive additive in patent application CN118007264A also reacts with the end groups of the molecular chain fragments, it cannot control the molecular weight distribution in a narrow range like the present invention, mainly because the distribution of the reactive additive in the polyester matrix is ​​different. The reactive additive in patent application CN118007264A is wrapped in a polypropylene polymer carrier, and the polyester molecular chain segments of different lengths are captured at the interface between polypropylene and polyester to form a modification effect of long and short branches. The reactive additive of the present invention is directly mixed in the biodegradable polyester and evenly dispersed in the polyester, which can effectively capture the molecular chain fragments after thermal decomposition, forming a modification effect of controlling the molecular weight distribution in a narrow range.

[0024] According to the method for preparing a biodegradable polyester fiber, the breaking strength of the biodegradable polyester fiber is ≥3.5 cN / dtex, and the breaking elongation is 30%-40%.

[0025] In the above-mentioned method for preparing a biodegradable polyester fiber, the polymeric carbodiimide is an aliphatic polycarbodiimide with a number average molecular weight of 1000-8000 g / mol.

[0026] In the method for preparing a biodegradable polyester fiber as described above, the biodegradable polyester is a copolymer of butylene adipate and butylene terephthalate, with a number average molecular weight of 30,000-55,000 g / mol and a melting point of 120-130°C.

[0027] As described above, a method for preparing a biodegradable polyester fiber adopts side-blowing cooling during melt spinning, the aspect ratio of the spinneret hole is 3-4.5:1, the spinning temperature is 230-250°C, the spinning temperature will affect the thermal degradation degree of the biodegradable polyester, the spinning speed is 800-1500m / min, the first winding roller (the roller that the filament first contacts after being ejected from the spinneret hole, mainly responsible for the preliminary winding and fixing of the filament) rotates at a speed of 50-200m / min, and the side-blowing temperature is 5-15°C.

[0028] In the method for preparing biodegradable polyester fiber as described above, the hot stretching adopts a first hot stretching roller and a second hot stretching roller, the temperature of the first hot stretching roller is 50-60°C, the temperature of the second hot stretching roller is 100-120°C, and the hot stretching ratio is 2-5 times.

[0029] In the method for preparing a biodegradable polyester fiber as described above, the heat setting temperature is 50-120°C, and a hot roller is used for heat setting. Due to the high spinning speed, the fiber stays on the hot roller for a short time for heat setting, and the heat setting time is in the millisecond range.

[0030] Beneficial Effects

[0031] (1) The present invention melt blends the reactive additive with the biodegradable polyester fiber. Without affecting the melt fluidity and processability, the reactive additive reacts with the end groups of the molecular chain fragments formed by the thermal degradation and rupture of the biodegradable polyester during the thermal processing. The reaction, on the one hand, inhibits the decrease in the molecular weight of the biodegradable polyester caused by the rupture of the biodegradable polyester molecular chain, and on the other hand, forms a branched structure uniformly distributed in the melt. The biodegradable polyester molecular chains are entangled through the branched structure to form physical entanglement points, thereby increasing the crystallization temperature of the biodegradable polyester and avoiding adhesion between the biodegradable polyester fiber bundles during the thermal processing.

[0032] (2) The present invention further promotes the reaction between the reactive additive and the end group of the molecular chain fragment of the biodegradable polyester by thermally stretching the pre-oriented fiber, thereby further reducing the molecular weight distribution index of the biodegradable polyester fiber.

[0033] (3) The process of the present invention is mild in conditions and simple in operation, and is suitable for large-scale industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a melting and crystallization curve diagram of the biodegradable polyester fiber of Comparative Example 1 without adding an additive;

[0035] Figure 2 1 is a melting and crystallization curve diagram of the biodegradable polyester fiber of Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0037] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0038] (1) Crystallization temperature of biodegradable polyester fiber: The thermal properties of biodegradable polyester were tested by differential scanning calorimetry. After drying each sample at 80°C in vacuum for 12 hours, 5-10 mg was weighed and placed in a crucible for sample preparation. In a N2 atmosphere with a flow rate of 50 mL / min, the temperature was increased from 40°C to 200°C at a rate of 20°C / min, kept at this temperature for 3 minutes, then cooled to -40°C at a rate of 10°C / min, kept at this temperature for 3 minutes, and then heated to 40°C at a rate of 10°C / min; the crystallization temperature was calculated from the cooling curve.

[0039] (2) Molecular weight distribution index of biodegradable polyester fiber: Gel permeation chromatography was used to test the molecular weight and molecular weight distribution of PBAT and modified PBAT slices. After each test sample was dried at 80°C in vacuum for 12 hours, 10-20 mg was weighed, and each sample was dissolved in 1 mL of hexafluoroisopropanol. After the blend / hexafluoroisopropanol solution with a concentration of 5-10 mg / mL was completely dissolved, it was extracted and filtered with a syringe until the solution was completely clear before testing; during the test, hexafluoroisopropanol was used as the mobile phase at a flow rate of 1 mL / min.

[0040] (3) Breaking strength of biodegradable polyester fiber: According to GB / T 14344-2022 “Test method for tensile properties of chemical fiber filaments”, the tensile breaking strength of biodegradable polyester fiber is evaluated by breaking strength.

[0041] (4) Elongation at break of biodegradable polyester fiber: According to GB / T 14344-2022 “Test method for tensile properties of chemical fiber filaments”, the tensile elongation at break of biodegradable polyester fiber was evaluated by elongation at break.

[0042] Example 1

[0043] A method for preparing biodegradable polyester fiber, the specific steps are as follows:

[0044] (1) Preparation of raw materials;

[0045] Reactive additive: aliphatic polycarbodiimide, molecular weight 1000-8000 g / mol; manufacturer: Shanghai Langyi New Material Technology Co., Ltd., brand: HyMax 210;

[0046] Biodegradable polyester: copolymer of butylene adipate and butylene terephthalate, number average molecular weight 30000-55000, melting point 120-130°C, manufacturer: Xinjiang Blue Mountain Tunhe Technology Co., Ltd., brand: TH801T;

[0047] (2) preparing pre-oriented fibers;

[0048] The reactive additive and the biodegradable polyester are uniformly mixed and melt-spun to obtain pre-oriented fibers; the mass ratio of the reactive additive to the biodegradable polyester is 3.0:97.0, side blowing cooling is adopted during melt spinning, the aspect ratio of the spinneret hole is 4.5:1, the spinning temperature is 230°C, the spinning speed is 800m / min, the rotation speed of the first winding roller is 50m / min, and the side blowing temperature is 15°C;

[0049] (3) preparing biodegradable polyester fibers;

[0050] The pre-oriented fiber is subjected to heat stretching and heat setting, wherein the heat stretching adopts a first heat stretching roller and a second heat stretching roller, the temperature of the first heat stretching roller is 50° C., the temperature of the second heat stretching roller is 100° C., the heat stretching ratio is 5 times, and the heat setting temperature is 100° C., thereby obtaining a biodegradable polyester fiber.

[0051] The final biodegradable polyester fiber has a breaking strength of 3.8 cN / dtex, a breaking elongation of 34%, and a melting and crystallization curve as shown in Figure 2 As shown, the crystallization temperature is 92°C, the molecular weight distribution index is 1.3, and there is no adhesion between the filaments during thermal processing.

[0052] Comparative Example 1

[0053] A method for preparing biodegradable polyester fiber is basically the same as that of Example 1, except that in step (2), no reactive auxiliary agent is added.

[0054] The final biodegradable polyester fiber has a breaking strength of 2.8 cN / dtex, a breaking elongation of 25%, and a melting and crystallization curve as shown in Figure 1 As shown, the crystallization temperature is 32°C, the molecular weight distribution index is 2.8, and there is adhesion between the filaments during thermal processing.

[0055] Comparative Example 2

[0056] A method for preparing biodegradable polyester fiber is basically the same as that of Example 1, except that in step (2), the mass ratio of the reactive auxiliary agent to the biodegradable polyester is 0.3:99.7.

[0057] The final biodegradable polyester fiber has a breaking strength of 3.2 cN / dtex, a breaking elongation of 28%, a crystallization temperature of 65° C., a molecular weight distribution index of 2.2, and no adhesion between the filament bundles during the thermal processing.

[0058] Comparative Example 3

[0059] A method for preparing biodegradable polyester fiber is basically the same as that of Example 1, except that in step (2), the mass ratio of the reactive auxiliary agent to the biodegradable polyester is 0.1:99.9.

[0060] The final biodegradable polyester fiber has a breaking strength of 3.0 cN / dtex, a breaking elongation of 27%, a crystallization temperature of 52° C., a molecular weight distribution index of 2.4, and adhesion between the filament bundles during the thermal processing.

[0061] Comparative Example 4

[0062] A method for preparing biodegradable polyester fiber is basically the same as that of Example 1, except that in step (2), the mass ratio of the reactive auxiliary agent to the biodegradable polyester is 8.0:92.0.

[0063] The final biodegradable polyester fiber has a breaking strength of 2.2 cN / dtex, an elongation at break of 80%, regularity destruction, no crystallization, and adhesion between filament bundles during thermal processing.

[0064] Comparing Example 1 with Comparative Examples 1-4, the breaking strength, breaking elongation, crystallization temperature and adhesion of the biodegradable polyester fiber prepared in Example 1 are significantly better than those of the biodegradable polyester fibers prepared in Comparative Examples 1-4, which indicates that adding too much or too little reactive additive is not conducive to improving the breaking strength, breaking elongation and crystallization temperature of the biodegradable polyester fiber and reducing the adhesion.

[0065] Example 2

[0066] A method for preparing biodegradable polyester fiber, the specific steps are as follows:

[0067] (1) Preparation of raw materials;

[0068] Reactive additive: aliphatic polycarbodiimide, molecular weight 1000-8000 g / mol; manufacturer: Shanghai Langyi New Material Technology Co., Ltd., brand: HyMax 210;

[0069] Biodegradable polyester: copolymer of butylene adipate and butylene terephthalate, number average molecular weight 30000-55000, melting point 120-130°C, manufacturer: Xinjiang Blue Mountain Tunhe Technology Co., Ltd., brand: TH801T;

[0070] (2) preparing pre-oriented fibers;

[0071] The reactive additive and the biodegradable polyester are uniformly mixed and melt-spun to obtain pre-oriented fibers; the mass ratio of the reactive additive to the biodegradable polyester is 1.5:98.5, side blowing cooling is adopted during melt spinning, the aspect ratio of the spinneret hole is 3.5:1, the spinning temperature is 243°C, the spinning speed is 1200m / min, the rotation speed of the first winding roller is 100m / min, and the side blowing temperature is 7°C;

[0072] (3) preparing biodegradable polyester fibers;

[0073] The pre-oriented fiber is subjected to heat stretching and heat setting, wherein the heat stretching adopts a first heat stretching roller and a second heat stretching roller, the temperature of the first heat stretching roller is 57° C., the temperature of the second heat stretching roller is 110° C., the heat stretching ratio is 3.5 times, and the heat setting temperature is 110° C., thereby obtaining a biodegradable polyester fiber.

[0074] The final biodegradable polyester fiber has a breaking strength of 3.7 cN / dtex, a breaking elongation of 40%, a crystallization temperature of 88° C., a molecular weight distribution index of 1.5, and no adhesion between the filament bundles during the thermal processing.

[0075] Example 3

[0076] A method for preparing biodegradable polyester fiber, the specific steps are as follows:

[0077] (1) Preparation of raw materials;

[0078] Reactive additive: aliphatic polycarbodiimide, molecular weight 1000-8000 g / mol; manufacturer: Shanghai Langyi New Material Technology Co., Ltd., brand: HyMax 210;

[0079] Biodegradable polyester: copolymer of butylene adipate and butylene terephthalate, number average molecular weight 30000-55000, melting point 120-130°C, manufacturer: Xinjiang Blue Mountain Tunhe Technology Co., Ltd., brand: TH801T;

[0080] (2) preparing pre-oriented fibers;

[0081] The reactive additive and the biodegradable polyester are uniformly mixed and melt-spun to obtain pre-oriented fibers; the mass ratio of the reactive additive to the biodegradable polyester is 0.5:99.5, side blowing cooling is adopted during melt spinning, the aspect ratio of the spinneret hole is 3:1, the spinning temperature is 250°C, the spinning speed is 1500m / min, the rotation speed of the first winding roller is 200m / min, and the side blowing temperature is 5°C;

[0082] (3) preparing biodegradable polyester fibers;

[0083] The pre-oriented fiber is subjected to heat stretching and heat setting, wherein the heat stretching adopts a first heat stretching roller and a second heat stretching roller, the temperature of the first heat stretching roller is 60° C., the temperature of the second heat stretching roller is 120° C., the heat stretching ratio is 2 times, and the heat setting temperature is 120° C., thereby obtaining a biodegradable polyester fiber.

[0084] The final biodegradable polyester fiber has a breaking strength of 3.9 cN / dtex, a breaking elongation of 30%, a crystallization temperature of 75°C, a molecular weight distribution index of 1.7, and no adhesion between the filament bundles during the thermal processing.

[0085] Example 4

[0086] A method for preparing biodegradable polyester fiber, the specific steps are as follows:

[0087] (1) Preparation of raw materials;

[0088] Reactive additive: Monomeric carbodiimide, manufacturer: Shanghai Langyi New Material Technology Co., Ltd., brand: HyMax1010;

[0089] Biodegradable polyester: polybutylene succinate (PBS), manufacturer: Xinjiang Blue Mountain Tunhe Technology Co., Ltd., brand: TH803S;

[0090] (2) preparing pre-oriented fibers;

[0091] The reactive additive and the biodegradable polyester are uniformly mixed and melt-spun to obtain pre-oriented fibers; the mass ratio of the reactive additive to the biodegradable polyester is 2.5:97.5, side blowing cooling is adopted during melt spinning, the aspect ratio of the spinneret hole is 3.5:1, the spinning temperature is 233°C, the spinning speed is 1000m / min, the rotation speed of the first winding roller is 100m / min, and the side blowing temperature is 10°C;

[0092] (3) preparing biodegradable polyester fibers;

[0093] The pre-oriented fiber is subjected to heat stretching and heat setting, wherein the heat stretching adopts a first heat stretching roller and a second heat stretching roller, the temperature of the first heat stretching roller is 55° C., the temperature of the second heat stretching roller is 110° C., the heat stretching ratio is 3 times, and the heat setting temperature is 110° C., thereby obtaining a biodegradable polyester fiber.

[0094] The final biodegradable polyester fiber has a breaking strength of 3.7 cN / dtex, a breaking elongation of 38%, a crystallization temperature of 85°C, a molecular weight distribution index of 1.4, and no adhesion between the filament bundles during the thermal processing.

[0095] Example 5

[0096] A method for preparing biodegradable polyester fiber is basically the same as Example 1, except that in step (2), the reactive auxiliary agent is aromatic polycarbodiimide, manufacturer: Shanghai Langyi New Material Technology Co., Ltd., brand: HyMax213.

[0097] The final biodegradable polyester fiber has a breaking strength of 3.5 cN / dtex, a breaking elongation of 40%, a crystallization temperature of 90°C, a molecular weight distribution index of 1.4, and no adhesion between the filament bundles during the thermal processing.

[0098] Example 6

[0099] A method for preparing biodegradable polyester fiber is basically the same as that of Example 1, except that in step (2), the mass ratio of the reactive auxiliary agent to the biodegradable polyester is 4.0:96.0.

[0100] The final biodegradable polyester fiber has a breaking strength of 3.8 cN / dtex, a breaking elongation of 37%, a crystallization temperature of 98°C, a molecular weight distribution index of 1.4, and no adhesion between the filament bundles during the thermal processing.

[0101] Example 7

[0102] A method for preparing biodegradable polyester fiber is basically the same as that of Example 1, except that in step (2), the mass ratio of the reactive auxiliary agent to the biodegradable polyester is 5.0:95.0.

[0103] The final biodegradable polyester fiber has a breaking strength of 3.7 cN / dtex, a breaking elongation of 40%, a crystallization temperature of 90°C, a molecular weight distribution index of 1.6, and no adhesion between the filament bundles during the thermal processing.

Claims

1. A method for preparing a biodegradable polyester fiber, characterized in that: The reactive additive and the biodegradable polyester are uniformly mixed, melt-spinned to obtain pre-oriented fibers, and then the pre-oriented fibers are heat-stretched and heat-set to obtain biodegradable polyester fibers; The reactive auxiliary agent is one or more of monomeric carbodiimide and polymeric carbodiimide; The mass ratio of the reactive auxiliary agent to the biodegradable polyester is 0.5:99.5-5.0:95.

0.

2. The method for preparing a biodegradable polyester fiber according to claim 1, characterized in that: The crystallization temperature of biodegradable polyester fiber is 75-100℃.

3. The method for preparing a biodegradable polyester fiber according to claim 1, characterized in that: The molecular weight distribution index of the biodegradable polyester fiber is ≤2.

4. The method for preparing a biodegradable polyester fiber according to claim 1, characterized in that: The breaking strength of the biodegradable polyester fiber is ≥3.5 cN / dtex, and the breaking elongation is 30%-40%.

5. The method for preparing a biodegradable polyester fiber according to claim 1, characterized in that: The polymeric carbodiimide is an aliphatic polycarbodiimide with a number average molecular weight of 1000-8000 g / mol.

6. The method for preparing a biodegradable polyester fiber according to claim 1, characterized in that: The biodegradable polyester is a copolymer of butylene adipate and butylene terephthalate, has a number average molecular weight of 30000-55000 g / mol, and a melting point of 120-130°C.

7. The method for preparing a biodegradable polyester fiber according to claim 1, characterized in that: During melt spinning, side blowing cooling is adopted, the aspect ratio of the spinneret hole is 3-4.5:1, the spinning temperature is 230-250°C, the spinning speed is 800-1500m / min, the first winding roller speed is 50-200m / min, and the side blowing temperature is 5-15°C.

8. The method for preparing a biodegradable polyester fiber according to claim 1, characterized in that: The hot stretching adopts a first hot stretching roller and a second hot stretching roller, the temperature of the first hot stretching roller is 50-60°C, the temperature of the second hot stretching roller is 100-120°C, and the hot stretching ratio is 2-5 times.

9. The method for preparing a biodegradable polyester fiber according to claim 1, characterized in that: The heat setting temperature is 50-120℃.

Images