High-strength polyester fiber material and method for producing the same

Abstract

The present application relates to the technical field of polyester fiber material, and particularly discloses a high-stability polyester fiber material and a preparation method thereof, wherein the polyester fiber material is a blended composite structure, and contains 40-70% of degradable polyester phase, 20-50% of high-performance polyester phase, 5-15% of cyclodextrin-polycaprolactone graft copolymer, 3-8% of polycarbonate diol and 0.3-1.0% of phosphate thermal stabilizer in terms of mass percentage; the preparation method comprises the following steps: preparing an interfacial compatibilizer, drying each component, pre-mixing according to the proportion, combining, melt blending extrusion by means of a double screw, and hot pressing; the present application improves the two-phase interface bonding through the interfacial compatibilizer, coordinates the degradation rate through the degradation regulator, suppresses the thermal degradation of polylactic acid through the optimization process, significantly improves the material stability and performance stability, and is suitable for packaging, textile and other fields.

Description

Technical Field

[0001] This invention belongs to the technical field of polyester fiber materials, specifically relating to a high-strength polyester fiber material and its preparation method. Background Technology

[0002] With the popularization of environmental protection concepts and the increase in related demands, the application of biodegradable polyester materials in various fields is receiving increasing attention. These materials can gradually degrade after use, reducing the burden on the environment, but their performance has certain limitations. For example, in terms of strength and weather resistance, they are often inferior to traditional high-performance polyester materials or other commonly used materials.

[0003] To balance environmental protection and performance, the industry often combines biodegradable polyester layers with traditional high-performance polyester layers or other material layers with specific properties to form composite polyester fiber materials.

[0004] During lamination, due to the differences in chemical structure between biodegradable polyester and traditional high-performance polyester or other materials, the interfacial compatibility is poor, making it difficult to form a tight and stable bond at the contact surface. This makes the material prone to delamination and peeling under external forces such as tension and friction. Simultaneously, the degradation rate of the biodegradable polyester layer is much faster than that of the traditional high-performance polyester layer or other non-biodegradable material layers. This asynchronous degradation leads to deformation, cracking, and performance degradation during material use. These problems result in the laminated material lacking good robustness and failing to meet the strength and lifespan requirements for practical applications.

[0005] This also limits the application of biodegradable polyester materials in combination with other high-performance materials, and restricts the promotion of composite polyester fiber materials in packaging, textiles, building materials and other fields. Summary of the Invention

[0006] The purpose of this invention is to provide a high-strength polyester fiber material and its preparation method to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A high-strength polyester fiber material, wherein the material is a blended composite structure, comprising the following components:

[0009] Biodegradable polyester phase, containing polylactic acid;

[0010] High-performance polyester phase, comprising polyethylene terephthalate;

[0011] Interface compatibilizer, comprising cyclodextrin-polycaprolactone graft copolymer;

[0012] Degradation regulators, including polycarbonate diol;

[0013] The interface compatibilizer is distributed at the interface between the two phases, and achieves interfacial compatibility through the inclusion of PLA segments in the cyclodextrin cavity and the entanglement of polycaprolactone segments with PET segments; the degradation regulator is dispersed in the composite matrix.

[0014] Preferably, the cyclodextrin-polycaprolactone graft copolymer is a graft copolymer obtained by grafting polycaprolactone segments onto a β-cyclodextrin core through a ring-opening polymerization reaction; the grafting rate of the graft copolymer is 30-50%, and the number average molecular weight of the polycaprolactone segments is 5000-10000.

[0015] Preferably, the components are expressed as a percentage by mass as follows:

[0016] Biodegradable polyester phase: 40-70%, of which polylactic acid content ≥90%;

[0017] High-performance polyester phase: 20-50%, of which polyethylene terephthalate content ≥90%;

[0018] Cyclodextrin-polycaprolactone graft copolymer: 5-15%;

[0019] Polycarbonate diol: 3-8%.

[0020] Preferably, it further includes 0.3-1.0% of a heat stabilizer, wherein the heat stabilizer is a phosphate ester compound; the polycarbonate diol has a number average molecular weight of 1000-2000 and a carbonate group content of ≥80%.

[0021] On the other hand, the present invention also provides a method for preparing a high-strength polyester fiber material, comprising the following steps:

[0022] S1. Preparation of cyclodextrin-polycaprolactone graft copolymer;

[0023] S2. After drying each component, mix them in proportion: first mix the cyclodextrin-polycaprolactone graft copolymer with polylactic acid, and mix the polycarbonate diol with polyethylene terephthalate, and then combine the two premixes.

[0024] S3. Melt blending extrusion is performed using a twin-screw extruder;

[0025] S4. Hot pressing is used to obtain the final product.

[0026] Preferably, the preparation conditions of the cyclodextrin-polycaprolactone graft copolymer in step S1 are as follows: using β-cyclodextrin and ε-caprolactone as raw materials, with a molar ratio of 1:10-20, and using stannous octoate as a catalyst, the reaction is carried out at 120-140°C for 4-8 hours.

[0027] Preferably, the process parameters for melt co-extrusion in step S3 are as follows: the twin-screw extruder is temperature-controlled in five sections: feeding section 190-200℃, compression section 210-220℃, melting section 235-245℃, metering section 225-235℃, and die head 215-225℃; the residence time of the material in the melting section is controlled at 1-2 minutes; and the screw speed is 200-300 r / min.

[0028] Preferably, the hot pressing process conditions in step S4 are: temperature 225-235℃, pressure 10-15MPa, and hot pressing time 5-10 minutes.

[0029] Preferably, the drying conditions in step S2 are as follows: polylactic acid is dried at 70°C for 6 hours, polyethylene terephthalate is dried at 120°C for 6 hours, and β-cyclodextrin is vacuum dried at 80°C for 12 hours; the heat stabilizer is vacuum dried at 50°C for 4 hours before mixing.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] (1) By introducing cyclodextrin-polycaprolactone graft copolymer as an interfacial compatibilizer, the cyclodextrin cavity in its molecular structure can form an inclusion complex with the polyethylene terephthalate (PET) molecular chain, while its polycaprolactone (PCL) segments have good affinity with the polylactic acid (PLA) molecular chain. This unique dual-function design enables the compatibilizer to significantly improve the interfacial adhesion between the PLA and PET phases and effectively suppress the phase separation phenomenon of the composite material.

[0032] (2) By introducing polycarbonate diol (PCDL) as a degradation regulator, the problem of early failure caused by the large difference in degradation rate of degradable / non-degradable composite materials can be solved. The degradation rate of PCDL is between that of PLA and PET. It forms a degradation buffer zone in the composite matrix, which effectively delays the damage process caused by the rapid degradation of PLA in the interface area.

[0033] (3) By optimizing the proportions of each component (such as the specific addition range of compatibilizers and regulators) and precisely controlling the process parameters of melt blending (such as zone temperature and residence time), the technical challenge of blending PLA (which is heat-sensitive) and PET (which has a high melting point) in the same system was successfully overcome. This process scheme ensures that the PET phase is fully plasticized and dispersed, while effectively inhibiting the thermal degradation and hydrolysis of the PLA phase during high-temperature processing, maintaining its molecular weight stability, thereby ensuring the feasibility and reproducibility of the final product performance. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Interface peel strength test

[0036] Test name: 90° peel strength, unit: N / m or N / mm;

[0037] Test objective: To quantitatively evaluate the interlayer or interphase interfacial adhesion performance of composite materials, and is the most direct mechanical indicator characterizing interfacial compatibility. A higher value indicates a stronger interfacial bond and less susceptibility to delamination or detachment.

[0038] Test Standard: The test method in this standard follows the national standard GB / T2790-1995 "Adhesives - 180° Peel Strength Test Method - Flexible Materials vs. Rigid Materials".

[0039] Test method: Cut the prepared composite material into strips of a specific width (e.g., 25 mm wide). Use a high-strength adhesive to attach the two ends of the strips back-to-back to two rigid metal plates, forming a T-shaped peel area. On a universal testing machine, perform a 90° peel at a constant speed (e.g., 100 mm / min), continuously recording the force curve during the peel process. The peel strength is calculated by dividing the average force of the curve by the strip width.

[0040] Tensile property test

[0041] Test names: tensile strength, elongation at break, tensile modulus of elasticity, units: MPa, %, MPa;

[0042] Test objective: To comprehensively evaluate the mechanical behavior of materials under uniaxial tensile loads. Tensile strength and modulus reflect the material's stiffness and resistance to deformation; elongation at break reflects the material's ductility and toughness. Good interfacial compatibility facilitates stress transfer, thereby enhancing these properties.

[0043] Test Standard: The test methods in this standard follow the national standard GB / T1040.2-2006 "Determination of Tensile Properties of Plastics - Part 2: Test Conditions for Molded and Extruded Plastics".

[0044] Test method: The material is injection molded or compression molded into a standard dumbbell-shaped specimen (e.g., type 1A). An axial tensile force is applied to the specimen on a universal testing machine at a specified constant speed (e.g., 5 mm / min or 50 mm / min) until the specimen breaks. The testing machine automatically records the stress-strain curve and calculates the tensile strength, elongation at break, and modulus of elasticity accordingly.

[0045] Cantilever beam notch impact strength

[0046] Test name: Notched impact strength of cantilever beam, unit: kJ / m 2 ;

[0047] Test Purpose: To quantitatively evaluate the toughness or notch sensitivity of a material under high-speed impact, especially suitable for assessing brittle materials or systems with poor compatibility. A higher value indicates better impact resistance and less brittle fracture. Improved interfacial compatibility typically significantly increases this value.

[0048] Test Standard: The test methods in this standard follow the national standard GB / T1843-2008 "Determination of Impact Strength of Plastic Cantilever Beams".

[0049] Test method: Prepare a notched strip specimen of the specified dimensions (e.g., 80*10*4mm, notch depth 2mm). Clamp the specimen vertically in the fixture of the impact testing machine, with the notch facing away from the impact pendulum. Release the pendulum, which has a certain potential energy, to impact the specimen. Record the energy consumed by the pendulum after breaking the specimen. Divide this energy value by the remaining thickness at the notch of the specimen to obtain the impact strength.

[0050] Controlled composting degradation experiment

[0051] Test name: Final aerobic biodegradation rate under composting conditions, unit: %

[0052] Test objective: To quantitatively evaluate the biodegradability of materials (especially biodegradable polyesters) under enhanced conditions simulating industrial composting. Accurately calculating the degradation rate by monitoring carbon dioxide emissions is the core basis for evaluating degradation synchronicity.

[0053] Test Standard: The test method in this standard follows the international standard ISO 14855-1:2012 "Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide - Part 1: General method".

[0054] Test Method: Samples with known dry weight and carbon content were mixed with inoculum (derived from mature compost) and placed in a large respiration reactor. The reactor was incubated under strictly controlled temperature (e.g., 58±2°C), humidity, and CO2-free air conditions. The amount of CO2 released was periodically measured and calculated using an alkaline trap or infrared gas analyzer. The theoretical CO2 yield of the material was calculated based on its carbon content: biodegradation percentage = (measured CO2 release / theoretical total CO2) × 100%.

[0055] Intrinsic viscosity test

[0056] Test name: Intrinsic viscosity, unit: dL / g;

[0057] Test objective: To indirectly characterize the average length (molecular weight) of polymer molecular chains. By comparing the rate of decrease in intrinsic viscosity of the PLA phase before and after processing, the degree of thermal degradation and hydrolysis during processing can be quantitatively assessed, which is a key indicator for demonstrating the stability and feasibility of the processing technology.

[0058] Test Standard: The test methods in this standard follow the national standard GB / T1632.1-2008 "Determination of Viscosity of Dilute Polymer Solutions Using Capillary Viscometers - Part 1: General Rules"

[0059] Test method: The PLA sample to be tested is precisely dissolved in a specific solvent (such as chloroform or tetrahydrofuran) to prepare a series of dilute solutions of different concentrations. Using an Ubbelohde capillary viscometer, the flow time of the solvent and the series of polymer solutions is measured in a constant temperature water bath (such as 25°C or 30°C). The intrinsic viscosity value at zero concentration is obtained by graphical extrapolation.

[0060] Example 1

[0061] A high-strength polyester fiber material, wherein the material is a blended composite structure and the total mass is 100 kg, comprises the following components:

[0062] The biodegradable polyester phase comprises 55%, with PLA content at 95% and a small amount of PBA at the remaining 5%, used only to improve the processing fluidity of PLA without affecting the overall degradation characteristics of the material. The initial intrinsic viscosity of PLA is 1.8 dL / g. The high-performance polyester phase comprises 30%, with PET content at 96% and a small amount of PBT at the remaining 4%, used to improve the dispersibility of PET with other components. The melt index of PET at 250℃ and 2.16 kg is 25 g / 10 min. The cyclodextrin-polycaprolactone graft copolymer (interfacial compatibilizer) comprises 10%, which is prepared by grafting PLC segments with β-cyclodextrin as the core through ring-opening polymerization. The grafting rate is 40%, and the number average molecular weight of PCL segments is 8000. The PCDL comprises 4%, with a number average molecular weight of 1500, carbonate group content of 85%, and hydroxyl value of 112 mgKOH / g. The heat stabilizer comprises 0.5%, which is TPP from phosphate ester compounds with a purity ≥99%.

[0063] A method for preparing a high-strength polyester fiber material includes the following steps:

[0064] S1: Weigh β-cyclodextrin and ε-caprolactone in a molar ratio of 1:15, with 1 mol of β-cyclodextrin (1134 g) and 15 mol of ε-caprolactone (1710 g). Add them to a four-necked flask equipped with a stirrer and a nitrogen protection device. Simultaneously add stannous octoate as a catalyst, with the amount of catalyst being 0.1% of the mass of ε-caprolactone (i.e., 1.71 g).

[0065] Next, the four-necked flask was placed in an oil bath and heated to 130°C. The mixture was stirred continuously at 200 rpm for 6 hours under a nitrogen atmosphere to ensure uniform reaction. After the reaction, the product was cooled to room temperature and washed three times with anhydrous ethanol to remove unreacted ε-caprolactone and residual catalyst. The washed product was then vacuum-dried at 80°C for 12 hours, finally yielding a white powdery cyclodextrin-polycaprolactone graft copolymer. Testing showed that the copolymer had a grafting rate of 40% and a PCL segment number-average molecular weight of 8000, meeting the design requirements.

[0066] S2: Place PLA in a forced-air drying oven and dry at 70℃ for 6 hours. After drying, the moisture content of PLA is ≤0.05%. Place PET in a vacuum drying oven and dry at 120℃ for 6 hours. After drying, the moisture content of PET is ≤0.03%. β-cyclodextrin used to prepare graft copolymers is vacuum dried at 80℃ for 12 hours beforehand. After drying, the moisture content is ≤0.02%. Heat stabilizer (TPP) is vacuum dried at 50℃ for 4 hours. After drying, the moisture content is ≤0.01%.

[0067] The premixing process consists of three steps: Step 1: Prepare the first premix by adding 10 kg of the cyclodextrin-polycaprolactone graft copolymer prepared in S1 and 52.25 kg of dried PLA (calculated by multiplying the total mass of the biodegradable polyester phase (55 kg) by the PLA content of 95%) to a high-speed mixer and mixing for 15 minutes at 80°C and 300 r / min to ensure uniform dispersion. Step 2: Prepare the second premix by adding 28.8 kg of dried PET (calculated by multiplying the total mass of the high-performance polyester phase (30 kg) by the PET content of 96%), 4 kg of PCDL, and 0.5 kg of heat stabilizer to a high-speed mixer and mixing for 20 minutes at 100°C and 300 r / min to ensure full compatibility between PCDL and PET. Step 3: Prepare the final mixture by combining the first and second premixes and transferring them to a low-speed mixer. Mix at 100 r / min at room temperature for 10 minutes to avoid excessive shearing that could cause the material to heat up, ultimately obtaining a uniform final mixture.

[0068] S3: It adopts a twin-screw extruder with model SHJ-35 and a length-to-diameter ratio of 40:1. In terms of segmented temperature control, the temperature of the feeding section is 195℃, the temperature of the compression section is 215℃, the temperature of the melting section is 240℃, the temperature of the metering section is 230℃, and the temperature of the die head is 220℃. In terms of key operating parameters, the screw speed is 250r / min, the residence time of the material in the melting section is 1.5 minutes, and the feeding rate is 20kg / h, ensuring stable material conveying without bridging.

[0069] During the extrusion process, the material is melt-blended by a twin-screw extruder, then cooled by water (water temperature 25℃), and then cut into pellets with a diameter of 3mm and a length of 3-4mm by a pelletizer. Finally, the pellets are vacuum dried at 80℃ for 4 hours to remove surface moisture and obtain blended pellets.

[0070] S4: The blended granules obtained in S3 are placed in a flat vulcanizing machine for hot pressing. The hot pressing temperature is set to 230℃, the hot pressing pressure to 12MPa, and the hot pressing time to 8 minutes. After hot pressing, cooling water (water temperature 20℃) is introduced into the flat vulcanizing machine to rapidly cool the material to below 60℃. Then, the material is demolded to obtain a high-strength polyester fiber material sample with dimensions of 150mm×150mm×3mm for subsequent performance testing.

[0071] Example 2

[0072] A high-strength polyester fiber material, wherein the material is a blended composite structure and the total mass is 100 kg, comprises the following components:

[0073] The biodegradable polyester phase comprises 65%, with PLA content at 93% and a small amount of PBA at the remaining 7%, used only to improve the processing fluidity of PLA without affecting the overall degradation characteristics of the material. The initial intrinsic viscosity of PLA is 1.6 dL / g. The high-performance polyester phase comprises 20%, with PET content at 94% and a small amount of PBT at the remaining 6%, used to improve the dispersibility of PET with other components. The melt index of PET at 250℃ and 2.16 kg is 24 g / 10 min. The cyclodextrin-polycaprolactone graft copolymer (interfacial compatibilizer) comprises 10%, which is prepared by grafting PLC segments with β-cyclodextrin as the core through ring-opening polymerization. The grafting rate is 38%, and the number average molecular weight of PCL segments is 7000. The PCDL comprises 4.5%, with a number average molecular weight of 1800, carbonate group content of 83%, and hydroxyl value of 120 mgKOH / g. The heat stabilizer comprises 0.5%, which is TPP from phosphate ester compounds with a purity ≥99%.

[0074] A method for preparing a high-strength polyester fiber material includes the following steps:

[0075] S1: Weigh β-cyclodextrin and ε-caprolactone in a molar ratio of 1:14, with 1 mol of β-cyclodextrin (1134 g) and 14 mol of ε-caprolactone (1596 g). Add both to a four-necked flask equipped with a stirrer and a nitrogen protection device. Simultaneously add stannous octoate as a catalyst, with the amount of catalyst being 0.1% of the mass of ε-caprolactone (i.e., 1.596 g).

[0076] Next, the four-necked flask was placed in an oil bath and heated to 135°C. The mixture was stirred continuously at 200 rpm for 7 hours under a nitrogen atmosphere to ensure uniform reaction. After the reaction, the product was cooled to room temperature and washed three times with anhydrous ethanol to remove unreacted ε-caprolactone and residual catalyst. The washed product was then vacuum-dried at 80°C for 12 hours, finally yielding a white powdery cyclodextrin-polycaprolactone graft copolymer. Testing showed that the copolymer had a grafting rate of 38% and a PCL segment number-average molecular weight of 7000, meeting the design requirements.

[0077] S2: Place PLA in a forced-air drying oven and dry at 70℃ for 6 hours. After drying, the moisture content of PLA is ≤0.05%. Place PET in a vacuum drying oven and dry at 120℃ for 6 hours. After drying, the moisture content of PET is ≤0.03%. β-cyclodextrin used to prepare graft copolymers is vacuum dried at 80℃ for 12 hours beforehand. After drying, the moisture content is ≤0.02%. Heat stabilizer (TPP) is vacuum dried at 50℃ for 4 hours. After drying, the moisture content is ≤0.01%.

[0078] The premixing process consists of three steps: Step 1: Prepare the first premix by adding 10 kg of the cyclodextrin-polycaprolactone graft copolymer prepared in S1 and 60.45 kg of dried PLA (calculated by multiplying the total mass of the biodegradable polyester phase (65 kg) by the PLA content of 93%) to a high-speed mixer and mixing for 16 minutes at 82°C and 300 r / min to ensure uniform dispersion. Step 2: Prepare the second premix by adding 18.8 kg of dried PET (calculated by multiplying the total mass of the high-performance polyester phase (20 kg) by the PET content of 94%), 4.5 kg of PCDL, and 0.5 kg of heat stabilizer to a high-speed mixer and mixing for 21 minutes at 102°C and 300 r / min to ensure full compatibility between PCDL and PET. Step 3: Prepare the final mixture by combining the first and second premixes and transferring them to a low-speed mixer. Mix at 100 r / min at room temperature for 10 minutes to avoid excessive shearing that could cause the material to heat up, ultimately obtaining a uniform final mixture.

[0079] S3: It adopts a twin-screw extruder with model SHJ-35 and a length-to-diameter ratio of 40:1. In terms of segmented temperature control, the temperature of the feeding section is 198℃, the temperature of the compression section is 218℃, the temperature of the melting section is 242℃, the temperature of the metering section is 232℃, and the die head temperature is 222℃. In terms of key operating parameters, the screw speed is 280r / min, the residence time of the material in the melting section is 1.8 minutes, and the feeding rate is 22kg / h, ensuring stable material conveying without bridging.

[0080] During the extrusion process, the material is melt-blended by a twin-screw extruder, then cooled by water (water temperature 24℃), and then cut into pellets with a diameter of 3mm and a length of 3-4mm by a pelletizer. Finally, the pellets are vacuum dried at 80℃ for 4 hours to remove surface moisture and obtain blended pellets.

[0081] S4: The blended granules obtained in S3 are placed in a flat vulcanizing machine for hot pressing. The hot pressing temperature is set to 232℃, the hot pressing pressure to 14MPa, and the hot pressing time to 9 minutes. After hot pressing, cooling water (water temperature 22℃) is introduced into the flat vulcanizing machine to rapidly cool the material to below 60℃. Then, the material is demolded to obtain a high-strength polyester fiber material sample with dimensions of 150mm×150mm×3mm for subsequent performance testing.

[0082] Example 3

[0083] A high-strength polyester fiber material, wherein the material is a blended composite structure and the total mass is 100 kg, comprises the following components:

[0084] The biodegradable polyester phase comprises 45%, with PLA content at 94% and a small amount of PBA at 6%, used only to improve the processing fluidity of PLA without affecting the overall degradation characteristics of the material. The initial intrinsic viscosity of PLA is 1.75 dL / g. The high-performance polyester phase comprises 40%, with PET content at 95% and a small amount of PBT at 5%, used to improve the dispersibility of PET with other components. The melt index of PET at 250℃ and 2.16 kg is 26 g / 10 min. The cyclodextrin-polycaprolactone graft copolymer (interfacial compatibilizer) comprises 10%, which is prepared by grafting PLC segments with β-cyclodextrin as the core through ring-opening polymerization. The grafting rate is 45%, and the number average molecular weight of PCL segments is 9000. The PCDL comprises 4.8%, with a number average molecular weight of 1600, carbonate group content of 84%, and hydroxyl value of 115 mgKOH / g. The heat stabilizer comprises 0.4%, which is TPP from phosphate ester compounds with a purity ≥99%.

[0085] A method for preparing a high-strength polyester fiber material includes the following steps:

[0086] S1: Weigh β-cyclodextrin and ε-caprolactone in a molar ratio of 1:18, with 1 mol of β-cyclodextrin (1134 g) and 18 mol of ε-caprolactone (2052 g). Add both to a four-necked flask equipped with a stirrer and a nitrogen protection device. Simultaneously add stannous octoate as a catalyst, with the amount of catalyst being 0.1% of the mass of ε-caprolactone (i.e., 2.052 g).

[0087] Next, the four-necked flask was placed in an oil bath and heated to 132°C. The mixture was stirred continuously at 200 rpm for 6.5 hours under a nitrogen atmosphere to ensure uniform reaction. After the reaction, the product was cooled to room temperature and washed three times with anhydrous ethanol to remove unreacted ε-caprolactone and residual catalyst. The washed product was then vacuum-dried at 80°C for 12 hours, finally yielding a white powdery cyclodextrin-polycaprolactone graft copolymer. Testing showed that the copolymer had a grafting rate of 45% and a PCL segment number-average molecular weight of 9000, meeting the design requirements.

[0088] S2: Place PLA in a forced-air drying oven and dry at 70℃ for 6 hours. After drying, the moisture content of PLA is ≤0.05%. Place PET in a vacuum drying oven and dry at 120℃ for 6 hours. After drying, the moisture content of PET is ≤0.03%. β-cyclodextrin used to prepare graft copolymers is vacuum dried at 80℃ for 12 hours beforehand. After drying, the moisture content is ≤0.02%. Heat stabilizer (TPP) is vacuum dried at 50℃ for 4 hours. After drying, the moisture content is ≤0.01%.

[0089] The premixing process consists of three steps: Step 1: Prepare the first premix by adding 10 kg of the cyclodextrin-polycaprolactone graft copolymer prepared in S1 and 42.3 kg of dried PLA (calculated by multiplying the total mass of the biodegradable polyester phase (45 kg) by the PLA content of 94%) to a high-speed mixer and mixing for 17 minutes at 83°C and 300 r / min to ensure uniform dispersion. Step 2: Prepare the second premix by adding 38 kg of dried PET (calculated by multiplying the total mass of the high-performance polyester phase (40 kg) by the PET content of 95%), 4.8 kg of PCDL, and 0.4 kg of heat stabilizer to a high-speed mixer and mixing for 23 minutes at 103°C and 300 r / min to ensure full compatibility between PCDL and PET. Step 3: Prepare the final mixture by combining the first and second premixes and transferring them to a low-speed mixer. Mix at 100 r / min at room temperature for 10 minutes to avoid excessive shearing that could cause the material to heat up, ultimately obtaining a uniform final mixture.

[0090] S3: It adopts a twin-screw extruder with model SHJ-35 and a length-to-diameter ratio of 40:1. In terms of segmented temperature control, the temperature of the feeding section is 196℃, the temperature of the compression section is 216℃, the temperature of the melting section is 243℃, the temperature of the metering section is 233℃, and the die head temperature is 223℃. In terms of key operating parameters, the screw speed is 260r / min, the material residence time in the melting section is 1.6 minutes, and the feeding rate is 21kg / h, ensuring stable material conveying without bridging.

[0091] During the extrusion process, the material is melt-blended by a twin-screw extruder, then cooled by water (water temperature 26℃), and then cut into pellets with a diameter of 3mm and a length of 3-4mm by a pelletizer. Finally, the pellets are vacuum dried at 80℃ for 4 hours to remove surface moisture and obtain blended pellets.

[0092] S4: The blended granules obtained in S3 were placed in a flat vulcanizing machine for hot pressing. The hot pressing temperature was set to 231℃, the hot pressing pressure to 13MPa, and the hot pressing time to 8.5 minutes. After hot pressing, cooling water (water temperature 21℃) was introduced into the flat vulcanizing machine to rapidly cool the material to below 60℃. Then, the material was demolded to obtain a high-strength polyester fiber material sample with dimensions of 150mm×150mm×3mm for subsequent performance testing.

[0093] Comparative Example 1

[0094] A polyester fiber material, wherein the material is a blended composite structure and the total mass is 100 kg, comprises the following components:

[0095] The biodegradable polyester phase accounts for 58%, of which PLA content is 95% and the remaining 5% is a small amount of PBA. The initial intrinsic viscosity of PLA is 1.8 dL / g. The high-performance polyester phase accounts for 32%, of which PET content is 96% and the remaining 4% is a small amount of PBT. The melt index of PET at 250℃ and 2.16kg is 25g / 10min. Acyclodextrin-polycaprolactone graft copolymer (interfacial compatibilizer) is used. PCDL accounts for 4%, with a number average molecular weight of 1500 and a carbonate group content of 85%. The heat stabilizer accounts for 0.5%, which is TPP with a purity of ≥99%.

[0096] A method for preparing a polyester fiber material includes the following steps:

[0097] S1: Preparation steps of acyclodextrin-polycaprolactone graft copolymer.

[0098] S2: Raw material drying: PLA is dried in a forced-air drying oven at 70℃ for 6 hours, and the moisture content after drying is ≤0.05%; PET is dried in a vacuum drying oven at 120℃ for 6 hours, and the moisture content after drying is ≤0.03%; heat stabilizer is vacuum dried at 50℃ for 4 hours, and the moisture content after drying is ≤0.01%; Premixing process: The dried PLA (55.1kg, 58kg×95%), PET (30.72kg, 32kg×96%), PCDL (4kg) and heat stabilizer (0.5kg) are directly added to a high-speed mixer and mixed for 20 minutes at 90℃ and 300r / min to obtain the total mixture.

[0099] S3: A twin-screw extruder of model SHJ-35 with a length-to-diameter ratio of 40:1 was used. The process parameters were the same as in Example 1 (feeding section 195℃, compression section 215℃, melting section 240℃, metering section 230℃, die head 220℃, screw speed 250r / min, melting section residence time 1.5 minutes, feeding rate 20kg / h). After extrusion, the material was water-cooled (water temperature 25℃), pelletized (diameter 3mm, length 3-4mm), and then vacuum-dried at 80℃ for 4 hours to obtain blended pellets.

[0100] S4: The hot pressing molding parameters are the same as in Example 1 (temperature 230℃, pressure 12MPa, time 8 minutes, cooling water temperature 20℃) to obtain a polyester fiber material sample.

[0101] Comparative Example 2

[0102] A polyester fiber material, wherein the material is a blended composite structure and the total mass is 100 kg, comprises the following components:

[0103] The biodegradable polyester phase accounts for 57%, of which PLA content is 95% and the remaining 5% is a small amount of PBA. The initial intrinsic viscosity of PLA is 1.8 dL / g. The high-performance polyester phase accounts for 31%, of which PET content is 96% and the remaining 4% is a small amount of PBT. The melt index of PET at 250℃ and 2.16kg is 25g / 10min. The cyclodextrin-polycaprolactone graft copolymer (interfacial compatibilizer) accounts for 10%, with a grafting rate of 40% and a PCL segment number-average molecular weight of 8000. PCDL is not present. The heat stabilizer accounts for 0.5%, and TPP with a purity of ≥99% is selected.

[0104] A method for preparing a polyester fiber material includes the following steps:

[0105] S1: The preparation steps of the cyclodextrin-polycaprolactone graft copolymer are the same as those in Example 1 (β-cyclodextrin to ε-caprolactone molar ratio 1:15, reaction at 130℃ for 6 hours, and after washing and drying, the grafting rate is 40% and the number-average molecular weight of PCL is 8000).

[0106] S2: Raw material drying: PLA was dried in a forced-air drying oven at 70℃ for 6 hours, and the moisture content after drying was ≤0.05%; PET was dried in a vacuum drying oven at 120℃ for 6 hours, and the moisture content after drying was ≤0.03%; β-cyclodextrin was vacuum dried at 80℃ for 12 hours in advance, and the moisture content after drying was ≤0.02%; heat stabilizer was vacuum dried at 50℃ for 4 hours, and the moisture content after drying was ≤0.01%; Premixing process: The preparation of the first premix was the same as in Example 1 (10 kg of graft copolymer and 54.15 kg of PLA were mixed at 80℃ and 300 r / min for 15 minutes); the second premix was dried PET (29.76 kg, 31 kg × 96%) and heat stabilizer (0.5 kg), mixed at 100℃ and 300 r / min for 20 minutes; the two premixes were combined and mixed at room temperature at 100 r / min for 10 minutes to obtain the total mixture.

[0107] S3: The twin-screw extrusion process parameters are the same as in Example 1. After extrusion, the material is pelletized and dried to obtain blended pellets.

[0108] S4: The hot pressing molding parameters are the same as in Example 1, and a polyester fiber material sample is obtained.

[0109] Comparative Example 3

[0110] A polyester fiber material, wherein the material is a blended composite structure and the total mass is 100 kg, comprises the following components:

[0111] The biodegradable polyester phase accounts for 55%, of which PLA content is 95% and the remaining 5% is a small amount of PBA. The initial intrinsic viscosity of PLA is 1.8 dL / g. The high-performance polyester phase accounts for 30%, of which PET content is 96% and the remaining 4% is a small amount of PBT. The melt index of PET at 250℃ and 2.16 kg is 25 g / 10 min. Maleic anhydride-grafted polyolefin elastomer (POE-g-MAH) replaces cyclodextrin-polycaprolactone graft copolymer, accounting for 10%, and the MAH grafting rate is 1.2%. PCDL accounts for 4%, with a number average molecular weight of 1500 and a carbonate group content of 85%. The heat stabilizer accounts for 0.5%, and TPP with a purity of ≥99% is selected.

[0112] A method for preparing a polyester fiber material includes the following steps:

[0113] S1: The preparation step of the acyclodextrin-polycaprolactone graft copolymer directly uses commercially available maleic anhydride grafted polyolefin elastomer (POE-g-MAH).

[0114] S2: Raw material drying: PLA was dried in a forced-air drying oven at 70℃ for 6 hours, and the moisture content after drying was ≤0.05%; PET was dried in a vacuum drying oven at 120℃ for 6 hours, and the moisture content after drying was ≤0.03%; the heat stabilizer was vacuum dried at 50℃ for 4 hours, and the moisture content after drying was ≤0.01%; Premixing process: The first premix was POE-g-MAH (10kg) and dried PLA (52.25kg, 55kg×95%), mixed at 80℃ and 300r / min for 15 minutes; the second premix was prepared in the same way as in Example 1 (PET 28.8kg, PCDL 4kg, heat stabilizer 0.5kg, mixed at 100℃ and 300r / min for 20 minutes); the two premixes were combined and mixed at room temperature at 100r / min for 10 minutes to obtain the total mixture.

[0115] S3: The twin-screw extrusion process parameters are the same as in Example 1. After extrusion, the material is pelletized and dried to obtain blended pellets.

[0116] S4: The hot pressing molding parameters are the same as in Example 1, and a polyester fiber material sample is obtained.

[0117] Comparative Example 4

[0118] A polyester fiber material, the composition of which is exactly the same as that of Example 1 (55% biodegradable polyester phase, 30% high-performance polyester phase, 10% cyclodextrin-polycaprolactone graft copolymer, 4% PCDL, 0.5% heat stabilizer, and the specifications of each component are the same as those of Example 1).

[0119] A method for preparing a polyester fiber material includes the following steps:

[0120] S1: The preparation steps of the cyclodextrin-polycaprolactone graft copolymer are the same as in Example 1.

[0121] S2: The raw material drying and premixing steps are completely consistent with those in Example 1 (PLA is dried at 70°C for 6 hours, PET is dried at 120°C for 6 hours, etc., and the premixing is divided into three steps to prepare the first and second premixes and the total mixture).

[0122] S3: A twin-screw extruder of model SHJ-35 with a length-to-diameter ratio of 40:1 was used. The extrusion process parameters deviated from the melt blending requirements in Example 1 and this invention: the segmented temperature control was 180°C for the feeding section, 200°C for the compression section, 220°C for the melting section, 210°C for the metering section, and 205°C for the die head; the screw speed was 180 r / min; the material residence time in the melting section was 3 minutes; the feeding rate was 15 kg / h; after extrusion, the material was water-cooled (water temperature 25°C), pelletized (diameter 3 mm, length 3-4 mm), and then vacuum-dried at 80°C for 4 hours to obtain blended pellets.

[0123] S4: The hot pressing molding parameters are the same as in Example 1, and a polyester fiber material sample is obtained.

[0124] The performance of the polyester fiber materials obtained in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4 was tested, and the results are shown in Tables 1-3.

[0125] Table 1: Interface Peel Strength Test

[0126] Interfacial peel strength (N / mm) Example 1 85 Example 2 87.2 Example 3 83.5 Comparative Example 1 62.3 Comparative Example 2 80.1 Comparative Example 3 72.5 Comparative Example 4 69.8

[0127] As can be seen from the data above, the interfacial peel strengths of Examples 1 to 3 reached 85.0 N / mm, 87.2 N / mm, and 83.5 N / mm, respectively, generally falling within the high value range of 83.5-87.2 N / mm, and the value fluctuation between examples was only 4.4% (based on Example 3, Example 2 showed the highest improvement of 4.4%). This stable performance stems from the specific component combination of the present invention, "cyclodextrin-polycaprolactone graft copolymer + polycarbonate diol," combined with optimized premixing and melt blending processes: the cyclodextrin cavity of the cyclodextrin-polycaprolactone graft copolymer can form an inclusion effect with the PLA chain segment, and its PLC chain segment can entangle with the PET chain segment. This dual-functional interface effectively inhibits the phase separation of PLA and PET, providing a solid structural foundation for high peel strength.

[0128] Compared to Comparative Example 1 (acyclodextrin-polycaprolactone graft copolymer), the advantages of the examples are more prominent: the interfacial peel strength of Example 1 (85.0 N / mm) is 36.4% higher than that of Comparative Example 1 (62.3 N / mm), Example 2 (87.2 N / mm) is 40.0% higher, and Example 3 (83.5 N / mm) is 34.0% higher. Furthermore, the strength of all examples is 21.2-24.9 N / mm higher than that of Comparative Example 1. This data clearly demonstrates that the cyclodextrin-polycaprolactone graft copolymer is the key component for improving the interfacial compatibility between PLA and PET. Comparative Example 1, lacking this compatibilizer, relies solely on physical mixing at the PLA-PET interface, resulting in weak adhesion and easy delamination under external forces, leading to a significant reduction in peel strength.

[0129] Further comparison with other comparative examples shows that the interfacial peel strength of Comparative Example 2 (lacking polycarbonate diol) is 80.1 N / mm, which is lower than that of the Example (difference of 3.6%-8.1%), but much higher than that of Comparative Example 1, and close to the value of the Example. This indicates that polycarbonate diol, as a degradation regulator in this invention, primarily functions to coordinate the synchronicity of PLA and PET degradation, with no significant impact on short-term interfacial peel strength. This further confirms that "cyclodextrin-polycaprolactone graft copolymer is the key component determining interfacial bonding strength." The strength of Comparative Example 3 (using maleic anhydride-grafted polyolefin elastomer (POE-g-MAH) instead of cyclodextrin-polycaprolactone graft copolymer) was 72.5 N / mm, higher than Comparative Example 1, but 10.5-14.7 N / mm lower than the examples. This demonstrates that conventional maleic anhydride graft compatibilizers have a far less effective interfacial modification effect on the PLA-PET system than the cyclodextrin-polycaprolactone graft copolymer specifically designed for this system in this invention. Conventional compatibilizers can only achieve limited bonding through polar groups, while the compatibilizer of this invention... The dual-action mechanism of "encapsulation + entanglement" results in a more precise and stable bonding effect at the PLA-PET interface, demonstrating the customized advantages of the compatibilizer in this invention. The strength of Comparative Example 4 (with deviation from twin-screw extrusion process parameters) is 69.8 N / mm, lower than that of Example 15.2-19.9 N / mm and also lower than that of Comparative Example 3. This is because the feeding section temperature of 180℃, the melting section temperature of 220℃, the screw speed of 180 r / min, and the melting section residence time of 3 minutes in its extrusion process led to uneven dispersion of the cyclodextrin-polycaprolactone graft copolymer in the matrix, and some compatibilizer failed to reach the PLA-PET interface to play its role. This indirectly proves that the process parameters set by this invention, such as segmented temperature control, screw speed, and melting section residence time, are important supports for ensuring the full play of the key components and achieving high interfacial peel strength.

[0130] Table 2: Tensile property test

[0131] Tensile strength (MPa) Elongation at break (%) Tensile modulus of elasticity (MPa) Example 1 58 18 2500 Example 2 56.5 17.2 2400 Example 3 59.2 18.5 2600 Comparative Example 1 45 12 2200 Comparative Example 2 55.2 16.8 2420 Comparative Example 3 50.3 14.5 2300 Comparative Example 4 48.5 13.2 2250

[0132] As can be seen from the data above, the high-strength polyester fiber materials in Examples 1 to 3 have significantly better tensile properties (tensile strength, elongation at break, and tensile modulus of elasticity) than the comparative examples, especially when key components are missing or the process is not optimized, which fully demonstrates their core value of strengthening mechanical load-bearing capacity.

[0133] Looking at the specific data, the tensile properties of Examples 1 to 3 are stable and excellent: tensile strength 56.5-59.2 MPa, elongation at break 17.2-18.5%, and tensile modulus of elasticity 2400-2600 MPa, with fluctuations of ≤4.8% among the examples. This is due to the component design and optimized process of the "cyclodextrin-polycaprolactone graft copolymer + polycarbonate diol" of this invention. The former improves interfacial compatibility through "encapsulation of PLA + entanglement of PET" to ensure efficient stress transfer; the performance of Example 2 is slightly reduced due to a slightly higher proportion of PLA, and the performance of Example 3 is slightly increased due to a slightly higher proportion of PET, which also reflects the rationality of the component ratio.

[0134] Compared with Comparative Example 1 (acyclodextrin-polycaprolactone graft copolymer), the examples show significant advantages: the tensile strength of Example 1 increased by 28.9% (45.0 MPa), the elongation at break (18.0%) increased by 50.0%, and the modulus (2500 MPa) increased by 13.6%; the improvements in Examples 2 and 3 also reached 25.6%-40.4% (tensile strength), 43.3%-54.2% (elongation at break), and 8.7%-18.2% (modulus). This proves that the compatibilizer is the key to ensuring tensile properties. Due to the absence of it, Comparative Example 1 has weak interfacial adhesion, poor stress transmission, and significantly reduced performance.

[0135] Compared with other comparative examples: Comparative Example 2 (without polycarbonate diol) had slightly lower performance than the Example (difference 3.1%-4.8%) but much higher performance than Comparative Example 1, indicating that it only coordinated degradation and did not affect short-term tensile properties; Comparative Example 3 (POE-g-MAH replacing compatibilizer) had lower performance than the Example (difference 8.8%-21.7%) because conventional compatibilizers cannot achieve a strong interfacial effect of "encapsulation + entanglement"; Comparative Example 4 (deviation of process parameters) had the worst performance because the compatibilizer was unevenly dispersed, which indirectly confirms the importance of the process parameters of this invention.

[0136] Table 3: Notched Impact Strength of Cantilever Beams

[0137] <![CDATA[Izod impact strength (kJ / m 2 )]]> Example 1 6.2 Example 2 6 Example 3 6.4 Comparative Example 1 4.5 Comparative Example 2 5.8 Comparative Example 3 5.2 Comparative Example 4 5

[0138] As can be seen from the data above, the high-strength polyester fiber materials in Examples 1 to 3 all exhibit significantly better cantilever beam notched impact strength than their counterparts, especially when key components are missing or the process is not optimized, fully demonstrating their core value in improving the material's impact resistance and toughness.

[0139] Based on the specific data, the impact strength of Examples 1 to 3 is consistently excellent: the values ​​are 6.0-6.4 kJ / m. 2 The variation between examples is ≤3.2%. This is due to the component design and optimized process of the "cyclodextrin-polycaprolactone graft copolymer + polycarbonate diol" of the present invention. The former strengthens the interfacial bonding by "cyclodextrin cavity encapsulating PLA segments and PCL segments entangled with PET segments", so that stress can be effectively transferred across the interface when subjected to external impact, avoiding interface fracture. In Example 2, the rigidity is enhanced and the impact strength is slightly reduced due to the slightly higher proportion of PLA. In Example 3, the deformation resistance is improved and the impact strength is slightly increased due to the slightly higher proportion of PET, which also reflects the rationality of the component ratio.

[0140] Compared with Comparative Example 1 (acyclodextrin-polycaprolactone graft copolymer), the examples show significant advantages: Example 1 has an impact strength of 6.2 kJ / m 2 Compared to its (4.5kJ / m 2 The efficiency was increased by 37.8% in Example 2 (6.0 kJ / m³). 2 The efficiency was increased by 33.3% in Example 3 (6.4 kJ / m³). 2 The performance was improved by 42.2%. This proves that the compatibilizer is the key to ensuring impact resistance. In the comparative example, due to the lack of it, the bond between PLA and PET was weak, making them prone to separation and breakage during impact, and the toughness was significantly reduced.

[0141] Compared with other comparative examples: Comparative Example 2 (without polycarbonate diol) impact strength (5.8kJ / m) 2 The strength of the sample was slightly lower than that of the example (within 6.5%) but much higher than that of Comparative Example 1, indicating that it only coordinated the synchronicity of degradation and did not affect the short-term impact toughness; the strength of Comparative Example 3 (POE-g-MAH as a compatibilizer) was 5.2 kJ / m. 2 The stress transfer efficiency was lower than that of the example (within 16.1%) because conventional compatibilizers could not achieve a strong interfacial effect of "encapsulation + entanglement," resulting in insufficient stress transfer efficiency; the strength of Comparative Example 4 (process parameter deviation) was 5.0 kJ / m. 2 The worst-case scenario is that the compatibilizer is not evenly dispersed, resulting in decreased interfacial bonding stability, which indirectly confirms the importance of the process parameters in this invention.

[0142] Table 4: Controlled composting degradation experiments

[0143] PLA phase biodegradation rate (%) Biodegradability of PET phase (%) PCDL phase biodegradation rate (%) Example 1 65 5 32 Example 2 68 5.2 35 Example 3 62 6 30 Comparative Example 1 63 5.1 31 Comparative Example 2 75 5 — Comparative Example 3 67 5.1 33 Comparative Example 4 69 5 28

[0144] As can be seen from the data above, the high-strength polyester fiber materials in Examples 1 to 3 exhibit significantly better synchronicity in the degradation of PLA, PET, and PCDL than the respective comparative examples. This advantage is even more pronounced when key components are missing or the process is not optimized, fully demonstrating its core value in coordinating the degradation rate of materials.

[0145] Based on the specific data, the degradation synchronicity of Examples 1 to 3 is stable and excellent: the biodegradation rate of PLA phase is 62.0%-68.0%, PET phase is 5.0%-6.0%, and PCDL phase is 30.0%-35.0%. The degradation rate of PCDL is always between that of PLA and PET, forming an effective degradation buffer, and the degradation rate matching degree of the three phases is high. In Example 2, the degradation rate of PLA increases slightly due to the slightly higher proportion of PLA, and in Example 3, the degradation rate of PET increases slightly due to the slightly higher proportion of PET. The overall fluctuations are mild, reflecting the rationality of the component ratio. This is due to the design of the present invention of "polycarbonate diol (PCDL) + cyclodextrin-polycaprolactone graft copolymer". PCDL acts as a degradation regulator, accurately coordinating the rate difference between PLA (easily degradable) and PET (difficult to degrade), while the compatibilizer ensures uniform dispersion of the three phases, further assisting in synchronous degradation.

[0146] Compared with Comparative Example 1 (acyclodextrin-polycaprolactone graft copolymer), the examples showed better synchronicity: Although Comparative Example 1 contained PCDL, with PLA degradation rates of 63.0%, PET of 5.1%, and PCDL of 31.0%, the lack of compatibilizer resulted in uneven PLA dispersion, leading to slightly lower degradation stability compared to the examples; while the three-phase degradation rate fluctuations of Examples 1 to 3 were ≤9.7% (PLA), 20.0% (PET), and 16.7% (PCDL), respectively, demonstrating more stable synchronicity. This proves the auxiliary role of the compatibilizer in the uniformity of degradation and also indicates that PCDL is the core factor in coordinating the degradation rate.

[0147] Compared with other comparative examples: Comparative Example 2 (without PCDL) showed extremely poor synchronicity, with PLA degradation rate of 75.0% and PET degradation rate of 5.0%, a difference of 70 percentage points, directly proving the indispensability of PCDL for degradation synchronicity; Comparative Example 3 (POE-g-MAH as a compatibilizer) showed PLA degradation rate of 67.0% and PCDL degradation rate of 33.0%, with slightly poorer PLA dispersion due to the conventional compatibilizer, resulting in slightly inferior synchronicity compared to the example; Comparative Example 4 (process parameter deviation) showed PCDL degradation rate of 28.0% and PLA degradation rate of 69.0%, with uneven PCDL dispersion due to improper process, weakened regulatory effect, and decreased synchronicity, indirectly confirming the importance of the process parameters of this invention.

[0148] Table 5: Intrinsic Viscosity Test

[0149] Initial intrinsic viscosity of PLA (dL / g) PLA intrinsic viscosity after processing (dL / g) PLA intrinsic viscosity reduction rate (%) Example 1 1.8 1.72 4.4 Example 2 1.7 1.62 4.7 Example 3 1.75 1.65 5.7 Comparative Example 1 1.8 1.68 6.7 Comparative Example 2 1.8 1.71 5 Comparative Example 3 1.8 1.69 6.1 Comparative Example 4 1.8 1.58 12.2

[0150] As can be seen from the data above, the high-strength polyester fiber materials in Examples 1 to 3 all showed a significantly lower rate of decrease in PLA intrinsic viscosity than the respective comparative examples. This advantage was particularly evident when the process was not optimized or when key components were missing, fully demonstrating their core value of inhibiting PLA processing thermal degradation and maintaining molecular weight stability.

[0151] Based on the specific data, the intrinsic viscosity stability of PLA in Examples 1 to 3 is excellent: the PLA intrinsic viscosity reduction rate is only 4.4%-5.7%, and the fluctuation between examples is ≤29.5% (based on Example 1). This stems from the design of the present invention of "optimized melt blending process + cyclodextrin-polycaprolactone graft copolymer". The former avoids PLA degradation due to high temperature or prolonged heating through the parameter combination of "feeding section 190-200℃, melting section 235-245℃, melting residence time of 1-2 minutes, and screw speed of 200-300 r / min"; the latter ensures uniform dispersion of PLA and PET, reducing PLA hydrolysis caused by local overheating. Under the dual effect, the molecular weight stability of PLA is strong. The reduction rate of PLA in Example 2 fluctuates slightly due to the slightly lower initial viscosity of PLA, and in Example 3 due to the slightly higher proportion of PET, further demonstrating the rationality of the component ratio and process synergy.

[0152] Compared with Comparative Example 1 (acyclic dextrin-polycaprolactone graft copolymer), the examples show significant advantages: the intrinsic viscosity of PLA in Comparative Example 1 decreased by 6.7%, which is 52.3% higher than that in Example 1. This was due to the lack of a compatibilizer, which led to uneven mixing of PLA and PET, slight local overheating during processing, and slightly accelerated thermal degradation of PLA. However, in Examples 1 to 3, thanks to the dispersing effect of the compatibilizer, PLA was heated more evenly, and the degradation rate remained at a low level, demonstrating the auxiliary role of the compatibilizer in the thermal stability of PLA.

[0153] Compared with other comparative examples: Comparative Example 2 (without polycarbonate diol) showed a decrease in PLA intrinsic viscosity of 5.0%, which is ≤13.6% different from the example, indicating that polycarbonate diol only coordinates the synchronicity of degradation and has no significant effect on the thermal stability of PLA processing; Comparative Example 3 (POE-g-MAH replacing cyclodextrin-polycaprolactone graft copolymer) showed a decrease of 6.1%, which is 38.6% higher than Example 1, because the conventional compatibilizer has a weaker dispersion effect on PLA-PET than the compatibilizer customized in this invention, increasing the risk of local degradation of PLA; Comparative Example 4 (deviation of twin-screw extrusion process parameters) showed a decrease of 12.2%, which is 114.0% higher than the highest value of the example, because the process combination of 180°C in the feeding section, 220°C in the melting section, 180 r / min screw speed, and 3 minutes residence time resulted in excessively long heating time and uneven plasticization of PLA, exacerbating thermal degradation and hydrolysis, which indirectly confirms the necessity of the process parameters set in this invention to inhibit PLA degradation.

[0154] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-strength polyester fiber material, characterized in that, The material is a blended composite structure, comprising the following components: Biodegradable polyester phase, containing polylactic acid; High-performance polyester phase, comprising polyethylene terephthalate; Interface compatibilizer, comprising cyclodextrin-polycaprolactone graft copolymer; Degradation regulators, including polycarbonate diol; The interface compatibilizer is distributed at the interface between the two phases, and achieves interfacial compatibility through the inclusion of PLA segments in cyclodextrin cavities and the entanglement of polycaprolactone segments with PET segments; the degradation regulator is dispersed in the composite matrix. The components are expressed as a percentage by mass: Biodegradable polyester phase: 40-70%, of which polylactic acid content ≥90%; High-performance polyester phase: 20-50%, of which polyethylene terephthalate content ≥90%; Cyclodextrin-polycaprolactone graft copolymer: 5-15%; Polycarbonate diol: 3-8%; The method for preparing the high-strength polyester fiber material includes the following steps: S1. Preparation of cyclodextrin-polycaprolactone graft copolymer; S2. After drying each component, mix them in proportion: first mix the cyclodextrin-polycaprolactone graft copolymer with polylactic acid, and mix the polycarbonate diol with polyethylene terephthalate, and then combine the two premixes. S3. Melt blending extrusion is performed using a twin-screw extruder; S4. Hot pressing is used to obtain the final product; The process parameters for melt co-extrusion described in step S3 are as follows: the twin-screw extruder is temperature-controlled in five sections: feeding section 190-200℃, compression section 210-220℃, melting section 235-245℃, metering section 225-235℃, and die head 215-225℃; the residence time of the material in the melting section is controlled at 1-2 minutes; and the screw speed is 200-300 r / min.

2. The high-strength polyester fiber material according to claim 1, characterized in that, The cyclodextrin-polycaprolactone graft copolymer is a graft copolymer obtained by grafting polycaprolactone segments onto a β-cyclodextrin core through a ring-opening polymerization reaction; the grafting rate of the graft copolymer is 30-50%, and the average molecular weight of the polycaprolactone segments is 5000-10000.

3. The high-strength polyester fiber material according to claim 1, characterized in that, It also includes 0.3-1.0% of a heat stabilizer, which is a phosphate ester compound; the polycarbonate diol has a number average molecular weight of 1000-2000 and a carbonate group content of ≥80%.

4. A method for preparing a high-strength polyester fiber material as described in claim 3, characterized in that, Includes the following steps: S1. Preparation of cyclodextrin-polycaprolactone graft copolymer; S2. After drying each component, mix them in proportion: first mix the cyclodextrin-polycaprolactone graft copolymer with polylactic acid, and mix the polycarbonate diol with polyethylene terephthalate, and then combine the two premixes. S3. Melt blending extrusion is performed using a twin-screw extruder; S4. Hot pressing is used to obtain the final product; The process parameters for melt co-extrusion described in step S3 are as follows: the twin-screw extruder is temperature-controlled in five sections: feeding section 190-200℃, compression section 210-220℃, melting section 235-245℃, metering section 225-235℃, and die head 215-225℃; the residence time of the material in the melting section is controlled at 1-2 minutes; and the screw speed is 200-300 r / min.

5. The preparation method according to claim 4, characterized in that, The preparation conditions of the cyclodextrin-polycaprolactone graft copolymer in step S1 are as follows: using β-cyclodextrin and ε-caprolactone as raw materials, with a molar ratio of 1:10-20, and using stannous octoate as catalyst, the reaction is carried out at 120-140℃ for 4-8 hours.

6. The preparation method according to claim 4, characterized in that, The hot pressing process conditions described in step S4 are: temperature 225-235℃, pressure 10-15MPa, and hot pressing time 5-10 minutes.

7. The preparation method according to claim 4, characterized in that, The drying conditions in step S2 are as follows: polylactic acid is dried at 70°C for 6 hours, and polyethylene terephthalate is dried at 120°C for 6 hours; the heat stabilizer is vacuum dried at 50°C for 4 hours before mixing.