Degradable synthetic fiber and process for preparing the same

Abstract

The application provides a degradable synthetic fiber and a preparation process thereof. The application first obtains a prepolymer containing an imide structure functional unit and a synthetic fiber polyester prepolymer, then polymerizes to obtain a modified synthetic fiber polyester, and further prepares a polyester fiber. The polyester fiber provided by the application is fully biodegradable and has the characteristics of high strength.

Description

Technical Field

[0001] This invention belongs to the field of polymers, and specifically relates to a biodegradable synthetic fiber and its preparation process. Background Technology

[0002] Synthetic fibers are fibers with textile properties made from artificially synthesized polymer compounds through processes such as preparing spinning solutions, spinning, and post-treatment.

[0003] As consumers increasingly demand comfort and aesthetic appeal in their clothing, synthetic fibers have become an irreplaceable component of textiles. However, their non-degradability has become a heavy burden on the environment. It is estimated that over one billion garments are discarded globally each year, and of those recycled, over 90% end up in landfills after processing. Like other non-degradable plastic products, these textiles also generate microplastics harmful to the environment and human health during wear and washing; in fact, reports indicate that textile microplastic particles are a major source of microplastics in the environment.

[0004] This shows that there is still a need for more high-strength, biodegradable fiber materials in the field of synthetic fibers. Summary of the Invention

[0005] This invention first provides a polyester for preparing biodegradable fibers, the polyester having a polyester main chain segment and a modified chain segment, the modified chain segment comprising the structure of Formula I:

[0006]

[0007] in:

[0008] R1 is a residue of a readily cyclic dicarboxylic acid;

[0009] R2 is a straight-chain or branched alkyl group with 2 or 3 carbon atoms;

[0010] The main chain segment contains C2-C for polymer synthesis. 10 Straight-chain or branched dicarboxylic acid residues and diol residues used in polymer synthesis.

[0011] Preferably, in the polyester used to prepare biodegradable fibers, the C2-C used for polymer synthesis 10 Straight-chain or branched dicarboxylic acid residues originate from C5-C 12 Straight-chain or branched dicarboxylic acids; the C5-C 12The straight-chain or branched dicarboxylic acid is selected from at least one of succinic acid, 2-methylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2,2,3,3-tetramethylsuccinic acid, oxalic acid, malonic acid, 1,6-adipic acid, 1,10-decanedioic acid, 1,18-octadecanoic acid, maleic acid, methylmaleic acid, dimethylmaleic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylglutaric acid, and diethylene glycol; more preferably, it is succinic acid or malonic acid.

[0012] Preferably, in the polyester used to prepare biodegradable fibers, the diol used for polymer synthesis is C2-C. 12 Aliphatic diols, including but not limited to ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol and 2,2-dimethyl-1,3-propanediol, or one or more of polyethylene glycol, polypropylene glycol and polytetrahydrofuran; more preferably ethylene glycol, 1,3-propanediol or 1,4-butanediol.

[0013] Preferably, in the polyester used to prepare biodegradable fibers, the main chain segment comprises polybutylene succinate (PBS) units.

[0014] Preferably, in the polyester used to prepare biodegradable fibers, the modified segment has the following block structure (II):

[0015]

[0016] Where m is greater than or equal to 1;

[0017] Preferably, m is selected from any integer from 1 to 10; more preferably, m is selected from any integer from 1 to 5.

[0018] Preferably, in the polyester used to prepare the biodegradable fiber, R2 is a residue of 2-amino-1,3-propanediol or 3-amino-1,2-propanediol.

[0019] Preferably, in the polyester used to prepare the biodegradable fiber, R1 is succinic acid, 2-methylsuccinic acid, 2-phenylsuccinic acid, 2-phenylmethylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2,3-diphenylsuccinic acid, 1,2-cyclosuccinic acid, 2,2,3,3-tetramethylsuccinic acid, methylmaleic acid, dimethylmaleic acid, phthalic acid, hexahydrophthalic acid, etc. The residues of acids, norbornyl edodecanic acid, tetrahydrophthalic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-phenylglutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylglutaric acid, diethylene glycol, 2,3-furandicarboxylic acid, 3,4-furandicarboxylic acid, 2,3-pyridinedicarboxylic acid, and 3,4-pyridinedicarboxylic acid, are more preferably residues of 1,4-succinic acid or its anhydride.

[0020] Preferably, in the polyester used to prepare biodegradable fibers, the modified segment accounts for 0.01%-25% of the total polyester segments in molar proportion.

[0021] Preferably, in the polyester used to prepare biodegradable fibers, the modified segment accounts for 0.01%-15% of the total polyester segments in a molar ratio; more preferably, it is 0.01%-10%.

[0022] Secondly, the present invention provides a method for synthesizing polyester for preparing biodegradable fibers as described in any of the foregoing claims, comprising the following steps 1)-3):

[0023] 1) Under conditions of excess dicarboxylic acid, dicarboxylic acid HOOC-R1-COOH or its ester or its anhydride is cyclized with amino diol HO-R2(NH2)-OH and prepolymerized to obtain a modified segmental polyester prepolymer with end carboxyl groups;

[0024] 2) Obtain polyester prepolymers with terminal hydroxyl groups in the main polyester unit;

[0025] 3) The modified segmental polyester prepolymer with terminal carboxyl groups and the polyester prepolymer with terminal hydroxyl groups are subjected to polycondensation to obtain the polyester used to prepare biodegradable fibers.

[0026] Preferably, in the method, the molar ratio of the dicarboxylic acid HOOC-R1-COOH to the amino diol HO-R2(NH2)-OH is 1.1-6:1;

[0027] Preferably, in the method, the amount of modified segment polyester prepolymer with terminal carboxyl groups added in step 3) is controlled such that the molar ratio of the modified segment to the total polyester segment is 0.01%-25%, preferably 0.01%-15%, and more preferably 0.01%-10%.

[0028] Preferably, in the method, the cyclization condition is a melt reaction.

[0029] Preferably, in the method, the cyclization in step 1) is carried out under melt heating conditions.

[0030] Preferably, in the method, the polyester prepolymer of step 1) or 2) is obtained by esterification, transesterification or polycondensation.

[0031] Thirdly, the present invention provides a fiber or a chip or masterbatch for preparing a fiber, said fiber or chip or masterbatch comprising the polyester described in any of the preceding claims for preparing a biodegradable fiber.

[0032] Preferably, the fiber or the chips or masterbatch used to prepare the fiber further contains additives, including at least one of heat stabilizers, viscosity promoters, fluorescent whitening agents, pigments, or antioxidants.

[0033] Preferably, in the fiber or the chips or masterbatch used to prepare the fiber, the fiber has a density greater than 4 cN·dtex. -1 The fracture strength.

[0034] Preferably, in the fiber or the slices or masterbatch from which the fiber is prepared, the fiber has an elongation at break of greater than 5%.

[0035] Fourthly, the present invention provides a method for preparing fibers, the method comprising: performing raw silk, winding, oiling, drawing and winding steps on polyester chips containing any of the preceding claims for preparing biodegradable fibers to obtain fibers.

[0036] Preferably, in the fiber preparation method, the drawing is performed using multi-stage rollers for step-by-step drawing.

[0037] Preferably, in the fiber preparation method, the multi-stage roller parameters are set as follows: GR1: 58-62℃, 440-560m / min; GR2: 63-67℃, 980-1040m / min; GR3: 68-72℃, 1600-1650m / min; GR4: 78-82℃, 2500-2700m / min; GR5: 78-82℃, 4000-4200m / min.

[0038] Fifthly, the present invention provides fiber articles made from the aforementioned fibers.

[0039] Preferably, the fiber product is a multi-component fiber, yarn, multifilament, fabric, or textile.

[0040] Beneficial technical effects

[0041] This invention first obtains a prepolymer containing imide structural functional units and a synthetic fiber polyester prepolymer, then polymerizes them to obtain a modified synthetic fiber polyester, and further prepares polyester fibers. The polyester fibers provided by this invention achieve full biodegradability while also possessing high strength. Attached Figure Description

[0042] Figure 1 Example 1: Melting point and enthalpy of fusion test results (the enthalpy of fusion of the slices in Example 1 is more than 10% higher than that of PBS; the enthalpy of fusion ΔH of the polyester slices in Example 1 of this invention). 0 m =66mJ / mg-68mJ / mg; enthalpy of melting of PBS slices ΔH 0 m =51.14mJ / mg).

[0043] Figure 2 Example 1: Results of melting point and enthalpy of melt-spun fibers.

[0044] Figure 3 The present invention provides a biodegradable, fully drawn filament roll. Detailed Implementation

[0045] Terminology definition:

[0046] The HOOC-R1-COOH is a readily cyclizable dicarboxylic acid, that is, a dicarboxylic acid that readily forms a cyclic anhydride in the absence of a catalyst or under catalytic conditions. Easily cyclizable dicarboxylic acids are known to those skilled in the art, for example, see CN110790906B. HOOC-R2-COOH may be selected from unsubstituted or substituted alkyl dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted cycloalkane dicarboxylic acids, substituted cycloalkene dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted aromatic dicarboxylic acids, substituted alkyl dicarboxylic acids, substituted cycloalkane ... Preferably, HOOC-R2-COOH is selected from at least one of succinic acid, 2-methylsuccinic acid, 2-phenylsuccinic acid, 2-phenylmethylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2,3-diphenylsuccinic acid, 1,2-cyclosuccinic acid, 2,2,3,3-tetramethylsuccinic acid, methylmaleic acid, dimethylmaleic acid, phthalic acid, hexahydrophthalic acid, norbornenic acid, tetrahydrophthalic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-phenylglutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylglutaric acid, diethylene glycol, 2,3-furandicarboxylic acid, 3,4-furandicarboxylic acid, 2,3-pyridinedicarboxylic acid, and 3,4-pyridinedicarboxylic acid. The cyclic anhydride of HOOC-R2-COOH is preferably selected from succinic anhydride, 2-methylsuccinic anhydride, 2-phenylbutyric anhydride, 2-benzylmethylsuccinic anhydride, 2,2-dimethylsuccinic anhydride, 2,3-dimethylsuccinic anhydride, 2,3-diphenylsuccinic anhydride, 1,2-cyclosuccinic anhydride, 2,2,3,3-tetramethylsuccinic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, phthalic acid, etc. At least one of the following: acid anhydride, hexahydrophthalic anhydride, norbornene anhydride, tetrahydrophthalic anhydride, glutaric anhydride, 2-methylglutaric anhydride, 3-methylglutaric anhydride, 3-phenylglutaric anhydride, 2,2-dimethylglutaric anhydride, 3,3-dimethylglutaric anhydride, diethylene glycol anhydride, 2,3-furandicarboxylic anhydride, 3,4-furandicarboxylic anhydride, 2,3-pyridinedicarboxylic anhydride, and 3,4-pyridinedicarboxylic anhydride.

[0047] The OH-R1(NH2)-OH is an amino-containing diol. The amino-containing diol may be selected from unsubstituted or substituted alkyl diolamines with substituents selected from halogens, alkyl groups, or nitro groups, or from unsubstituted or substituted alkyl-aryl-alkyl diolamines with substituents selected from halogens, alkyl groups, or nitro groups. Preferably, the amino-containing diol may be selected from at least one of 3-amino-1,2-propanediol, 2-amino-1,3-propanediol, 2-amino-1,3-butanediol, 2-amino-1,4-butanediol, 2-amino-1,5-pentanediol, 3-amino-1,5-pentanediol, 5-amino-1,3-benzenedimethanol, and 2-amino-1,3-phenylenedimethanol.

[0048] Synthetic methods for preparing biodegradable fibers of polyester

[0049] This invention synthesizes polyester through a three-step method:

[0050] 1) Under conditions of excess dicarboxylic acid, dicarboxylic acid HOOC-R1-COOH or its ester or its anhydride is cyclized with aminodiol HO-R2(NH2)-OH and prepolymerized to obtain a modified prepolymer with terminal carboxyl group;

[0051] 2) Obtain the prepolymer of the polyester main unit;

[0052] 3) The prepolymer of the modified unit with the terminal carboxyl group and the prepolymer of the polyester host unit are subjected to polycondensation to obtain the polyester.

[0053] The cyclization reaction in step 1) can be carried out under conventional conditions in the art, such as under melt heating conditions.

[0054] Step 1) The reaction to synthesize the prepolymer can be carried out under conventional conditions in the art, such as under reduced pressure, heating and catalysis, preferably catalyzed by zinc acetate, for example.

[0055] The polyester prepolymer with terminal hydroxyl groups of the polyester host unit in step 2) can be obtained by conventional methods in the art, such as using an transesterification catalyst.

[0056] In step 3), the prepolymer is melt-polymerized under suitable polymer conditions, typically by polycondensation under reduced pressure, at elevated temperatures, and in the presence of a suitable catalyst. The temperature is preferably in the range of about the polymer's melting point to about 30°C above that melting point, but preferably not less than about 180°C. The pressure should preferably be gradually reduced, preferably reduced to as low as possible. The polycondensation catalyst can be a titanium(IV) alkoxide or titanium(IV) chelate, a zirconium(IV) chelate, or a zirconium(IV) salt (e.g., an alkoxide); a hafnium(IV) chelate; titanates, silicates, and metal acetates can also be used as catalysts.

[0057] The indicators in the examples and comparative examples were tested according to the following standards or methods:

[0058] Melt flow index (g / 10min) test reference standard: GB / T 3682.1-2018, test conditions: temperature: 190℃, load: 2.16kg;

[0059] The reference standard for fracture strength (cN / dtex) testing is GB / T 14344-2022.

[0060] Elongation at break (%) test reference standard: GB / T 14344-2022.

[0061] Example

[0062] Example 1 (1% molar addition of 3-amino-1,2-propanediol modified segment)

[0063] Slice synthesis

[0064] Step 1: 210.57g of 3-amino-1,2-propanediol, dried at low temperature, and 818.95g of 1,4-succinic acid were added to reactor A. The mixture was stirred at room temperature, and nitrogen was used to completely replace the air in the reactor. Then, the mixture was slowly heated and melted in a nitrogen atmosphere at a nitrogen flow rate of 50mL / min. The mixture was stirred at a constant temperature for 3h to obtain an imide diol monomer.

[0065] In the second step, after the imidization reaction is completed, 100 ppm of zinc acetate catalyst (relative to the weight of the entire reaction system, the same below) is added, and the reaction is carried out at 160℃ and -0.08MPa for 2 hours to obtain the modified unit prepolymer.

[0066] Step 3: In a 100L stainless steel polymerization apparatus B, add 26.75kg of succinic acid, 26.81g of 1,4-butanediol, 200ppm of the catalyst n-butyl titanate, and 50ppm of the heat stabilizer triphenyl phosphate, and stir at room temperature until homogeneous. Replace the air in the reactor completely with nitrogen, then slowly raise the temperature to 190℃ at a rate of 5℃ / 10min, confirming that the distillation fraction reaches more than 95% of the theoretical amount, thus obtaining polybutylene succinate prepolymer.

[0067] Step 4: Using nitrogen gas, the amount of terminal carboxyl diamine monomer obtained in step 2 is forced into the reactor through the constant pressure feeding port on polymerization device B for co-esterification reaction for 1 hour. Then, the temperature is raised to 240℃ and polycondensation reaction is carried out under negative pressure of 50Pa. After that, the product is stretched, granulated, and dried to obtain biodegradable material slices 1 with a melt index of 9.8g / 10min.

[0068] Fiber preparation

[0069] The obtained biodegradable material chips were dried in a rotary drum vacuum at 60℃, and the moisture content was found to be below 50ppm. The experimental melt spinning machine (spinning assembly pressure: 10-20MPa; number of spinnerets: 36) had five temperature zones from 100℃ to 180℃ from the feed port to the die head, with the pipeline temperature and the chamber temperature both at 180℃. Multi-stage roller drawing was used, with the following hot roller settings: GR1: 60℃, 510m / min; GR2: 65℃, 1020m / min; GR3: 70℃, 1632m / min; GR4: 80℃, 2610m / min; GR5: 80℃, 4178m / min. After raw silk spinning, winding, oiling, drawing, and winding, biodegradable melt-spun filament 1 was obtained, with a breaking strength of 5.9cN / dtex and a breaking elongation of 23.5%.

[0070] Example 2 (2% molar addition of 3-amino-1,2-propanediol modified segment)

[0071] Step 1: 419.14g of 3-amino-1,2-propanediol, dried at low temperature, and 1630.07g of 1,4-succinic acid were added to reactor A. The mixture was stirred at room temperature, and nitrogen was used to completely replace the air in the reactor. Then, the mixture was slowly heated and melted in a nitrogen atmosphere at a nitrogen flow rate of 50mL / min. The mixture was stirred at a constant temperature for 3h to obtain an imide diol monomer.

[0072] In the second step, after the imidization reaction is completed, 100 ppm of zinc acetate catalyst (relative to the weight of the entire reaction system, the same below) is added, and the reaction is carried out at 160℃ and -0.08MPa for 2 hours to obtain the carboxyl-terminated modified unit prepolymer.

[0073] Step 3: In a 100L stainless steel polymerization apparatus B, add 26.08 kg of succinic acid, 26.41 g of 1,4-butanediol, 200 ppm of the catalyst n-butyl titanate, and 50 ppm of the heat stabilizer triphenyl phosphate, and stir at room temperature until homogeneous. Replace the air in the reactor completely with nitrogen, then slowly raise the temperature to 190°C at a rate of 5°C / 10 min, confirming that the distillation fraction reaches more than 95% of the theoretical amount, thus obtaining polybutylene succinate prepolymer.

[0074] Step 4: Using nitrogen gas, the amount of terminal carboxyl diamine monomer obtained in step 2 is forced into the reactor through the constant pressure feeding port on polymerization device B for co-esterification reaction for 1 hour. Then, the temperature is raised to 240℃ and polycondensation reaction is carried out under a negative pressure of 50Pa. After that, the product is stretched, granulated, and dried to obtain biodegradable material slices 2 with a melt index of 9.4g / 10min.

[0075] Fiber preparation

[0076] The obtained biodegradable material chips were dried in a rotary drum vacuum at 60℃, and the moisture content was found to be below 50ppm. The experimental melt spinning machine (spinning assembly pressure: 10-20MPa; number of spinnerets: 36) had five temperature zones from 100℃ to 180℃ from the feed port to the die head, with the pipeline temperature and the chamber temperature both at 180℃. Multi-stage roller drawing was used, with the following hot roller settings: GR1: 60℃, 510m / min; GR2: 65℃, 1020m / min; GR3: 70℃, 1632m / min; GR4: 80℃, 2610m / min; GR5: 80℃, 4178m / min. After raw silk spinning, winding, oiling, drawing, and winding, biodegradable melt-spun filament 2 was obtained, with a breaking strength of 6.1cN / dtex and a breaking elongation of 18.8%.

[0077] Example 3 (3% molar addition of 3-amino-1,2-propanediol modified segment)

[0078] Step 1: 625.71g of 3-amino-1,2-propanediol, dried at low temperature, and 2433.49g of 1,4-succinic acid were added to reactor A. The mixture was stirred at room temperature, and nitrogen was used to completely replace the air in the reactor. Then, the mixture was slowly heated and melted in a nitrogen atmosphere at a nitrogen flow rate of 50mL / min. The mixture was stirred at a constant temperature for 3h to obtain an imide diol monomer.

[0079] In the second step, after the imidization reaction is completed, 100 ppm of zinc acetate catalyst (relative to the weight of the entire reaction system, the same below) is added, and the reaction is carried out at 160℃ and -0.08MPa for 2 hours to obtain the carboxyl-terminated modified unit prepolymer.

[0080] Step 3: In a 100L stainless steel polymerization apparatus B, add 25.42 kg of succinic acid, 26.01 g of 1,4-butanediol, 200 ppm of the catalyst n-butyl titanate, and 50 ppm of the heat stabilizer triphenyl phosphate, and stir at room temperature until homogeneous. Replace the air in the reactor completely with nitrogen, then slowly raise the temperature to 190°C at a rate of 5°C / 10 min, confirming that the distillation fraction reaches more than 95% of the theoretical amount, thus obtaining polybutylene succinate prepolymer.

[0081] Step 4: Using nitrogen gas, the amount of terminal carboxyl diamine monomer obtained in step 2 is forced into the reactor through the constant pressure feeding port on polymerization device B for co-esterification reaction for 1 hour. Then, the temperature is raised to 240℃ and polycondensation reaction is carried out under a negative pressure of 50Pa. After that, the product is stretched, granulated, and dried to obtain biodegradable material slices 3 with a melt index of 9.7g / 10min.

[0082] Fiber preparation

[0083] The obtained biodegradable material chips were dried in a rotary drum vacuum at 60℃, and the moisture content was found to be below 50ppm. The experimental melt spinning machine (spinning assembly pressure: 10-20MPa; number of spinnerets: 36) had five temperature zones from 100℃ to 180℃ from the feed port to the die head, with the pipeline temperature and the chamber temperature both at 180℃. Multi-stage roller drawing was used, with the following hot roller settings: GR1: 60℃, 400m / min; GR2: 65℃, 800m / min; GR3: 70℃, 1280m / min; GR4: 80℃, 2048m / min; GR5: 80℃, 3277m / min. After raw silk spinning, winding, oiling, drawing, and winding, biodegradable melt-spun filament 3 was obtained, with a breaking strength of 4.8cN / dtex and a breaking elongation of 35.8%.

[0084] Example 4 (1% molar addition of 2-amino-1,3-propanediol modified segment)

[0085] Step 1: 210.57g of 2-amino-1,3-propanediol and 818.95g of 1,4-succinic acid, dried at low temperature, were added to reactor A. The mixture was stirred at room temperature, and nitrogen was used to completely replace the air in the reactor. Then, the mixture was slowly heated and melted in a nitrogen atmosphere at a nitrogen flow rate of 50mL / min. The mixture was stirred at a constant temperature for 3h to obtain an imide diol monomer.

[0086] In the second step, after the imidization reaction is completed, 100 ppm of zinc acetate catalyst (relative to the weight of the entire reaction system, the same below) is added, and the reaction is carried out at 160℃ and -0.08MPa for 2 hours to obtain the carboxyl-terminated modified unit prepolymer.

[0087] Step 3: In a 100L stainless steel polymerization apparatus B, add 26.75kg of succinic acid, 26.81g of 1,4-butanediol, 200ppm of the catalyst n-butyl titanate, and 50ppm of the heat stabilizer triphenyl phosphate, and stir at room temperature until homogeneous. Replace the air in the reactor completely with nitrogen, then slowly raise the temperature to 190℃ at a rate of 5℃ / 10min, confirming that the distillation fraction reaches more than 95% of the theoretical amount, thus obtaining polybutylene succinate prepolymer.

[0088] Step 4: Using nitrogen gas, the amount of terminal carboxyl diamine monomer obtained in step 2 is forced into the reactor through the constant pressure feeding port on polymerization device B for co-esterification reaction for 1 hour. Then, the temperature is raised to 240℃ and polycondensation reaction is carried out under a negative pressure of 50Pa. After that, the product is stretched, granulated, and dried to obtain biodegradable material slices 4 with a melt index of 9.8g / 10min.

[0089] Fiber preparation

[0090] The obtained biodegradable material chips were dried in a rotary drum vacuum at 60℃, and the moisture content was found to be below 50ppm. The experimental melt spinning machine (spinning assembly pressure: 10-20MPa; number of spinnerets: 36) had five temperature zones from 100℃ to 180℃ from the feed port to the die head, with the pipeline temperature and the chamber temperature both at 180℃. Multi-stage roller drafting was used, with the following hot roller settings: GR1: 60℃, 510m / min; GR2: 65℃, 1020m / min; GR3: 70℃, 1632m / min; GR4: 80℃, 2610m / min; GR5: 80℃, 4178m / min. After raw silk spinning, winding, oiling, drafting, and winding, biodegradable melt-spun filament 4 was obtained, with a breaking strength of 5.7cN / dtex and a breaking elongation of 24.7%.

[0091] Comparative Example

[0092] Preparation of polybutylene succinate slices

[0093] In a 100L stainless steel polymerization apparatus, 28.72 kg of succinic acid, 28.49 g of 1,4-butanediol, 200 ppm of tetrabutyl titanate catalyst, and 50 ppm of triphenyl phosphate heat stabilizer were added and stirred at room temperature. The air inside the reactor was completely replaced with nitrogen, and then the temperature was slowly increased to 190°C at a rate of 5°C / 10 min until the distillation fraction reached more than 95% of the theoretical amount, thus obtaining polybutylene succinate prepolymer. The temperature was then further increased to 245°C, and polycondensation reaction was carried out under a negative pressure of 50 Pa. Afterwards, the product was stretched, granulated, and dried to obtain biodegradable material chips 5 with a melt index of 9.4 g / 10 min.

[0094] Fiber preparation

[0095] The obtained biodegradable material chips were dried in a rotary drum vacuum at 60℃, and the moisture content was found to be below 50ppm. The experimental melt spinning machine (spinning assembly pressure: 10-20MPa; number of spinnerets: 36) had five temperature zones from the feed port to the die head, ranging from 100℃ to 220℃, with a pipe temperature of 210℃ and a chamber temperature of 220℃. Traditional two-stage stretching was used, with the hot roller settings: GR1: 60℃, 1500m / min; GR2: 65℃, 2700m / min. Raw yarn, take-up, oiling, drawing, and winding were performed to obtain biodegradable melt-spun filament 5, with a breaking strength of 3.3cN / dtex and a breaking elongation of 46.8%.

[0096] Those skilled in the art should note that the embodiments described in this invention are merely illustrative, and various other substitutions, changes, and improvements can be made within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is defined only by the claims.

Claims

1. A polyester for preparing biodegradable fibers, said polyester having a polyester backbone segment and a modified segment, said modified segment comprising the structure of Formula I: in: R1 is a residue of a readily cyclic dicarboxylic acid; R2 is a straight-chain or branched alkyl group with 2 or 3 carbon atoms; The main chain segment contains C2-C for polymer synthesis. 10 Straight-chain or branched dicarboxylic acid residues and diol residues used in polymer synthesis; Preferably, the C2-C used for polymer synthesis 10 Straight-chain or branched dicarboxylic acid residues originate from C5-C 12 Straight-chain or branched dicarboxylic acids; the C5-C 12 The straight-chain or branched dicarboxylic acid is selected from at least one of succinic acid, 2-methylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2,2,3,3-tetramethylsuccinic acid, oxalic acid, malonic acid, 1,6-adipic acid, 1,10-decanedioic acid, 1,18-octadecanoic acid, maleic acid, methylmaleic acid, dimethylmaleic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylglutaric acid, and diethylene glycol; more preferably, it is succinic acid or malonic acid. Preferably, the diol used for polymer synthesis is C2-C. 12 Aliphatic diols, including but not limited to ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol and 2,2-dimethyl-1,3-propanediol, or one or more of polyethylene glycol, polypropylene glycol and polytetrahydrofuran; more preferably ethylene glycol, 1,3-propanediol or 1,4-butanediol.

2. The polyester for preparing biodegradable fibers as described in claim 1, wherein the main chain segment comprises polybutylene succinate (PBS) units.

3. The polyester for preparing biodegradable fibers as described in claim 1 or 2, wherein the modified segment has the following block structure (II): Where m is greater than or equal to 1; Preferably, m is selected from any integer from 1 to 10; more preferably, m is selected from any integer from 1 to 5.

4. The polyester for preparing biodegradable fibers as described in any one of claims 1-3, in, R2 is a residue of 2-amino-1,3-propanediol or 3-amino-1,2-propanediol; Preferably, R1 is a residue of succinic acid, 2-methylsuccinic acid, 2-phenylsuccinic acid, 2-phenylmethylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2,3-diphenylsuccinic acid, 1,2-cyclosuccinic acid, 2,2,3,3-tetramethylsuccinic acid, methylmaleic acid, dimethylmaleic acid, phthalic acid, hexahydrophthalic acid, norbornenic acid, tetrahydrophthalic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 3-phenylglutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylglutaric acid, diethylene glycol, 2,3-furandicarboxylic acid, 3,4-furandicarboxylic acid, 2,3-pyridinedicarboxylic acid, or 3,4-pyridinedicarboxylic acid; more preferably, it is a residue of 1,4-succinic acid or its anhydride.

5. The polyester for preparing biodegradable fibers according to any one of claims 1-4, wherein the modified segment accounts for 0.01%-25% of the total polyester segments in molar proportion.

6. The polyester for preparing biodegradable fibers according to any one of claims 1-5, wherein the modified segment accounts for 0.01%-15% of the total polyester segments in a molar ratio; preferably, 0.01%-10%.

7. The method for synthesizing polyester for preparing biodegradable fibers as described in any one of claims 1-6, comprising steps 1)-3) below: 1) Under conditions of excess dicarboxylic acid, dicarboxylic acid HOOC-R1-COOH or its ester or its anhydride is cyclized with amino diol HO-R2(NH2)-OH and prepolymerized to obtain a modified segmental polyester prepolymer with end carboxyl groups; 2) Obtain polyester prepolymers with terminal hydroxyl groups in the main polyester unit; 3) The modified segmental polyester prepolymer with terminal carboxyl groups and the polyester prepolymer with terminal hydroxyl groups are subjected to polycondensation to obtain the polyester used to prepare biodegradable fibers. Preferably, the molar ratio of the dicarboxylic acid HOOC-R1-COOH to the amino diol HO-R2(NH2)-OH is 1.1-6:1; Preferably, the amount of modified segment polyester prepolymer with terminal carboxyl groups added in step 3) is controlled such that the molar ratio of the modified segment to the total polyester segment is 0.01%-25%, preferably 0.01%-15%, and more preferably 0.01%-10%. Preferably, the cyclization condition is a melt reaction; Preferably, the cyclization in step 1) is carried out under molten heating conditions; Preferably, the polyester prepolymer of step 1) or 2) is obtained by esterification, transesterification or polycondensation.

8. A fiber or a chip or masterbatch for preparing a fiber, said fiber or chip or masterbatch comprising the polyester for preparing a biodegradable fiber as described in any one of claims 1-6; Preferably, the fiber further comprises additives, the additives including at least one of heat stabilizers, viscosity promoters, optical brighteners, pigments or antioxidants; Preferably, the fiber has a density greater than 4 cN·dtex. -1 The fracture strength; Preferably, the fiber has a breaking elongation greater than 5%.

9. A method for preparing a fiber, the method comprising: Fibers are obtained by subjecting chips containing the polyester described in any one of claims 1-6 to the steps of raw filament preparation, winding, oiling, drawing, and winding; preferably, the drawing is performed using multi-stage rollers; more preferably, the parameters of the multi-stage rollers are set as follows: GR1: 58-62℃, 440-560m / min; GR2: 63-67℃, 980-1040m / min; GR3: 68-72℃, 1600-1650m / min; GR4: 78-82℃, 2500-2700m / min; GR5: 78-82℃, 4000-4200m / min.

10. A fiber article made from the fiber of claim 8; Preferably, the fiber product is a multi-component fiber, yarn, multifilament, fabric, or textile.

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