Plant source composite anti-ultraviolet functional polyamide filament and preparation method thereof

Abstract

The invention relates to the technical field of chinlon, in particular to a plant-source composite anti-ultraviolet functional chinlon filament and a preparation method thereof, and the plant-source composite anti-ultraviolet functional chinlon filament comprises the following raw materials: nylon 6, a functionalized lignin compound, tetra [beta-(3, 5-di-tert-butyl-4-hydroxyphenylpropionic acid) propyl] pentaerythritol ester and polyvinylpyrrolidone. According to the invention, furan groups are introduced into the lignin, so that the polar structure of the lignin can be effectively adjusted, the dispersion stability of the lignin in an organic phase system is improved, the lignin and polyamide molecules can form hydrogen bonds and pi-pi interaction, the interface bonding force and compatibility are remarkably enhanced, and the spinning defect caused by agglomeration of traditional lignin is avoided; the conjugated double bond in the furan ring and the aromatic skeleton of the lignin have a synergistic effect, so that ultraviolet radiation energy can be shielded, and non-radiation dissipation can be realized, thereby inhibiting the photooxidation fracture of the chinlon molecular chain and improving the ultraviolet aging resistance of the filament.

Description

Technical Field

[0001] This invention relates to the field of nylon technology, and more specifically, to a plant-derived composite UV-resistant nylon filament and its preparation method. Background Technology

[0002] Nylon (polyamide) filaments are widely used in clothing, industrial fabrics, and functional fiber materials due to their excellent mechanical strength, abrasion resistance, and elasticity. However, the nylon molecular backbone contains a large number of amide bonds, which are prone to photo-oxidative degradation under ultraviolet light irradiation, leading to molecular chain breakage, decreased mechanical properties, and surface yellowing. Current UV-resistant modification technologies mainly include adding inorganic nanoparticles (such as TiO2 and ZnO) or organic UV absorbers (such as benzotriazoles and hindered amines). Although inorganic particles have good UV shielding capabilities, their poor dispersibility and weak interfacial bonding can easily cause spinning problems such as yarn breakage and filter clogging. Organic UV absorbers are prone to decomposition and volatilization under high-temperature melt spinning conditions (>240℃), resulting in insufficient long-term stability and a certain environmental burden, making it difficult to meet the requirements of green textiles.

[0003] Lignin is an abundant aromatic polymer in nature with excellent UV absorption and antioxidant properties, and is regarded as a potential plant-derived UV-resistant functional material. However, natural lignin is highly polar and has poor thermal stability, poor compatibility with non-polar polymers such as polyamides, and is prone to agglomeration and uneven dispersion in the matrix, thus limiting its application in engineering plastics and fiber materials. In view of this, we propose a plant-derived composite UV-resistant functional nylon filament and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a plant-derived composite UV-resistant nylon filament and its preparation method, in order to solve the problems mentioned in the background art, such as the strong polarity and poor thermal stability of natural lignin, its poor compatibility with non-polar polymers such as polyamide, and its tendency to agglomerate and disperse unevenly in the matrix, which limits its application in engineering plastics and fiber materials.

[0005] This invention provides a plant-derived composite UV-resistant nylon filament, comprising the following raw materials: nylon 6, functionalized lignin complex, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl], and polyvinylpyrrolidone; The functionalized lignin complex is prepared by introducing furan functional groups on the surface of lignin nanoparticles to form a covalent structure.

[0006] Preferably, the nylon 6 comprises 80-90 parts by weight, the functionalized lignin complex comprises 5-10 parts by weight, the pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl] comprises 0.1-0.5 parts by weight, and the polyvinylpyrrolidone comprises 0.1-1 parts by weight.

[0007] Preferably, the functionalized lignin complex is prepared by the following method: Lignin nanoparticles were dispersed in anhydrous tetrahydrofuran and stirred at 300-600 rpm for 15-20 min under nitrogen to obtain a dispersion with a solid content of 5-10%. Triethylamine was added to the dispersion and cooled to 0-5℃. Then, 2-furanoyl chloride was added dropwise over a period of 10-30 min. After the addition was complete, the mixture was stirred at 0-5℃ for 30 min, then heated to 20-25℃ and stirred for another 4-6 h. After the reaction was completed, the mixture was filtered, washed 2-3 times with ethanol / water at a volume ratio of 1:1, and dried under vacuum to obtain the functionalized lignin complex.

[0008] Preferably, the amount of triethylamine used is 1.0-1.2 times the molar amount of 2-furanoyl chloride.

[0009] Preferably, the molar ratio of the lignin hydroxyl group to 2-furanoyl chloride is 1:0.1-0.3.

[0010] Preferably, the vacuum drying temperature is 40-50℃, the vacuum degree is 0.1-0.5mbar, and the drying time is 12-24h.

[0011] Preferably, the particle size of the functionalized lignin complex is 80-200 nm.

[0012] On the other hand, the present invention provides a method for preparing plant-derived composite UV-resistant functional nylon filaments, which includes the following steps: S1.1 Weigh the following raw materials in parts by weight: 80-90 parts by weight of nylon 6, 5-10 parts by weight of functionalized lignin complex, 0.1-0.5 parts by weight of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl] pentaerythritol ester, and 0.1-1 parts by weight of polyvinylpyrrolidone. S1.2. Dry the above raw materials in hot air at 80-90℃ for 4-6 hours, then add them to a twin-screw extruder for melt mixing, hold for 1-3 minutes, extrude, cool and granulate to obtain composite masterbatch; S1.3. The composite masterbatch is melt-spun to obtain plant-derived composite UV-resistant nylon filament.

[0013] Preferably, in step S1.2, the twin-screw extruder temperature is 225-235℃ and the screw speed is 100-300rpm.

[0014] Preferably, in step S1.3, the cooling draw ratio is 2.5-3.5 times, and the heat setting temperature is 110-130℃.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, a plant-derived composite UV-resistant nylon filament and its preparation method are disclosed. By introducing furan groups into lignin, its polar structure can be effectively adjusted, improving its dispersion stability in the organic phase system. This allows lignin to form hydrogen bonds and π-π interactions with polyamide molecules, significantly enhancing interfacial bonding and compatibility, and avoiding spinning defects caused by the aggregation of traditional lignin. The conjugated double bonds in the furan ring synergistically work with the aromatic skeleton of lignin to shield UV radiation energy and achieve non-radiative dissipation, thereby inhibiting the photo-oxidative breakage of nylon molecular chains and improving the UV aging resistance of the filament. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] This invention provides a plant-derived composite UV-resistant nylon filament, comprising the following raw materials: nylon 6, functionalized lignin complex, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl], and polyvinylpyrrolidone; The functionalized lignin complex is prepared by introducing furan functional groups on the surface of lignin nanoparticles to form a covalent structure.

[0018] Nylon 6 (CAS No. 25038-54-4, particle size 20-40 mesh), tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl] pentaerythritol ester (CAS No. 6683-19-8, purity 98%), and polyvinylpyrrolidone (CAS No. 9003-39-8, purity K-30, molecular weight 40000) were all purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0019] Preparation method of lignin nanoparticles: Lignin is dissolved in ethyl acetate to form a homogeneous solution; water is slowly added and emulsified at high speed (8000-20000 r / min, 20-60 seconds) to form an emulsion; the organic solvent is evaporated at 60-80℃, and lignin self-assembles into micro / nanospheres; centrifugation (8000-10000 r / min) and washing are performed, followed by freeze drying to obtain lignin nanoparticles.

[0020] The lignin is alkali lignin (CAS No. 8068-05-1, model: L-003, purchased from Shandong Dadi Ruichen Chemical Co., Ltd.).

[0021] Triethylamine (CAS No. 121-44-8, purity 99%) was purchased from Shandong Zhengxing New Materials Co., Ltd.

[0022] 2-Furfural chloride (CAS No. 527-69-5, purity 99%) was purchased from Jiangsu Congzhong Chemical Co., Ltd.

[0023] Example 1: A method for preparing a plant-derived composite UV-resistant nylon filament, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 80 parts by weight of nylon 6, 5 parts by weight of functionalized lignin complex, 0.1 parts by weight of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl], and 0.1 parts by weight of polyvinylpyrrolidone. S1.2. The above raw materials are dried in hot air at 80℃ for 4 hours, and then added to a twin-screw extruder for melt mixing at 225℃ and 100 rpm for 1 minute. After extrusion, cooling and granulation, composite masterbatch is obtained. S1.3 The composite masterbatch is melt-spun, cooled with a draw ratio of 2.5 times, and heat-set at 110℃ to obtain plant-derived composite UV-resistant nylon filament.

[0024] The preparation method of functionalized lignin complex is as follows: Lignin nanoparticles were dispersed in anhydrous tetrahydrofuran and stirred at 300 rpm for 15 min under nitrogen to obtain a dispersion with a solid content of 5%. Triethylamine (1.0 times the molar amount of 2-furanoyl chloride) was added to the dispersion, and the mixture was cooled to 0 °C. Then, 2-furanoyl chloride (molar ratio of lignin hydroxyl groups to 2-furanoyl chloride was 1:0.1) was added dropwise over 10 min. After the addition was complete, the mixture was stirred at 0 °C for 30 min, then heated to 20 °C and stirred for another 4 h. After the reaction was completed, the mixture was filtered, washed twice with ethanol / water at a volume ratio of 1:1, and dried under vacuum at 40 °C for 12 h at a vacuum degree of 0.1 mbar to obtain a functionalized lignin complex (particle size of 80 nm).

[0025] Example 2: A method for preparing a plant-derived composite UV-resistant nylon filament, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 80 parts by weight of nylon 6, 5 parts by weight of functionalized lignin complex, 0.1 parts by weight of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl], and 0.1 parts by weight of polyvinylpyrrolidone. S1.2. The above raw materials are dried in hot air at 80℃ for 4 hours, and then added to a twin-screw extruder for melt mixing at 225℃ and 100 rpm for 1 minute. After extrusion, cooling and granulation, composite masterbatch is obtained. S1.3 The composite masterbatch is melt-spun, cooled with a draw ratio of 2.5 times, and heat-set at 110℃ to obtain plant-derived composite UV-resistant nylon filament.

[0026] The preparation method of functionalized lignin complex is as follows: Lignin nanoparticles were dispersed in anhydrous tetrahydrofuran and stirred at 300 rpm for 15 min under nitrogen to obtain a dispersion with a solid content of 5%. Triethylamine (1.0 times the molar amount of 2-furanoyl chloride) was added to the dispersion, and the mixture was cooled to 0 °C. Then, 2-furanoyl chloride (molar ratio of lignin hydroxyl groups to 2-furanoyl chloride was 1:0.2) was added dropwise over 10 min. After the addition was complete, the mixture was stirred at 0 °C for 30 min, then heated to 20 °C and stirred for another 4 h. After the reaction was completed, the mixture was filtered, washed twice with ethanol / water at a volume ratio of 1:1, and dried under vacuum at 40 °C for 12 h at a vacuum degree of 0.1 mbar to obtain a functionalized lignin complex (particle size of 80 nm).

[0027] Example 3: A method for preparing a plant-derived composite UV-resistant nylon filament, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 80 parts by weight of nylon 6, 5 parts by weight of functionalized lignin complex, 0.1 parts by weight of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl], and 0.1 parts by weight of polyvinylpyrrolidone. S1.2. The above raw materials are dried in hot air at 80℃ for 4 hours, and then added to a twin-screw extruder for melt mixing at 225℃ and 100 rpm for 1 minute. After extrusion, cooling and granulation, composite masterbatch is obtained. S1.3 The composite masterbatch is melt-spun, cooled with a draw ratio of 2.5 times, and heat-set at 110℃ to obtain plant-derived composite UV-resistant nylon filament.

[0028] The preparation method of functionalized lignin complex is as follows: Lignin nanoparticles were dispersed in anhydrous tetrahydrofuran and stirred at 300 rpm for 15 min under nitrogen to obtain a dispersion with a solid content of 5%. Triethylamine (1.0 times the molar amount of 2-furanoyl chloride) was added to the dispersion, and the mixture was cooled to 0 °C. Then, 2-furanoyl chloride (molar ratio of lignin hydroxyl groups to 2-furanoyl chloride was 1:0.3) was added dropwise over 10 min. After the addition was complete, the mixture was stirred at 0 °C for 30 min, then heated to 20 °C and stirred for another 4 h. After the reaction was completed, the mixture was filtered, washed twice with ethanol / water at a volume ratio of 1:1, and dried under vacuum at 40 °C for 12 h at a vacuum degree of 0.1 mbar to obtain a functionalized lignin complex (particle size of 80 nm).

[0029] Determination of furan substitution degree: Weigh 20 mg of dry sample and place it in a dry test tube. Under inert conditions, prepare a standard solution and add 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxophosphazenecyclopentane to phosphorylate all measurable hydroxyl groups. The reaction is completed by stirring at room temperature for 20-30 min. Take a sample into an NMR tube and measure the ^31PNMR spectrum. Integrate different chemical shift regions (phenol OH, alcohol OH, etc.). Quantify the sample by integrating with known standard substances and calculate the total hydroxyl group (mmol / g). Then, calculate DS (%) based on the difference between the factory or original LNP total hydroxyl group value and the value before and after the reaction.

[0030] Determination of thermal stability: Weigh 5-10 mg of dry sample into a TGA sample pan, and heat it from room temperature to 800 °C at a rate of 10 °C / min under a nitrogen atmosphere. Record the mass loss curve (TG) and thermal weight loss rate (DTG). T5% is the temperature at which the sample mass loss reaches 5%. In the TGA, rapidly heat to 250 °C (representing the upper limit of melt processing), hold at 250 °C for 30 min, and record the percentage of mass loss within 30 min (representing the tendency of volatilization / thermal decomposition under short-term high temperature in melt extrusion / spinning).

[0031] Table 1 Performance data of functionalized lignin complexes Furan Substitution Degree DS T5% Isothermal weight loss at 250℃ Example 1 9.8 mol% 305℃ 1.2% Example 2 17.5 mol% 298℃ 2.8% Example 3 24.1 mol% 290℃ 5.1% As the molar ratio of 2-furan carboxyl chloride changed from 0.10 to 0.30 (relative to lignin hydroxyl groups), the degree of furan substitution increased from 9.8% to 24.1%, indicating that the molar addition of acid acyl chloride under the reaction conditions can effectively control the degree of substitution.

[0032] Thermal stability decreased slightly with increasing furan substitution degree: T5% decreased from 305℃ (Example 1) to 290℃ (Example 3), indicating that the thermal stability of the sample decreased slightly with the increase of introduced esterified furan groups. This is because ester bonds / newly introduced low molecular weight organic fragments are more prone to cracking or volatilization at high temperatures.

[0033] Isothermal weight loss (processing tolerance) is significantly affected by furan substitution degree: under isothermal conditions of 250℃ for 30 min, the weight loss of Example 1 is only 1.2%, indicating good stability at common PA6 melt processing temperatures; while the weight loss of Example 3 reaches 5.1%, suggesting that samples with high substitution degree may cause volatile release, color changes or affect masterbatch / spinning stability during melt processing.

[0034] Example 4: A method for preparing a plant-derived composite UV-resistant nylon filament, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 85 parts of nylon 6, 5 parts of functionalized lignin complex, 0.3 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl], and 0.5 parts of polyvinylpyrrolidone. S1.2. The above raw materials are dried in hot air at 85℃ for 5 hours, and then added to a twin-screw extruder for melt mixing at 235℃ and 200 rpm for 2 minutes. After extrusion, cooling and granulation, composite masterbatch is obtained. S1.3. The composite masterbatch is melt-spun, cooled with a draw ratio of 3.0, and heat-set at 120℃ to obtain plant-derived composite UV-resistant nylon filament.

[0035] The preparation method of functionalized lignin complex is as follows: Lignin nanoparticles were dispersed in anhydrous tetrahydrofuran and stirred at 400 rpm for 18 min under nitrogen to obtain a dispersion with a solid content of 6%. Triethylamine (1.1 times the molar amount of 2-furanoyl chloride) was added to the dispersion, and the mixture was cooled to 4 °C. Then, 2-furanoyl chloride (molar ratio of lignin hydroxyl groups to 2-furanoyl chloride was 1:0.2) was added dropwise over 20 min. After the addition was complete, the mixture was stirred at 4 °C for 30 min, then heated to 25 °C and stirred for another 5 h. After the reaction was completed, the mixture was filtered, washed three times with ethanol / water at a volume ratio of 1:1, and dried under vacuum at 45 °C for 16 h at a vacuum degree of 0.3 mbar to obtain a functionalized lignin complex (particle size of 100 nm).

[0036] Example 5: A method for preparing a plant-derived composite UV-resistant nylon filament, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 85 parts of nylon 6, 8 parts of functionalized lignin complex, 0.3 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl], and 0.5 parts of polyvinylpyrrolidone. S1.2. The above raw materials are dried in hot air at 85℃ for 5 hours, and then added to a twin-screw extruder for melt mixing at 235℃ and 200 rpm for 2 minutes. After extrusion, cooling and granulation, composite masterbatch is obtained. S1.3. The composite masterbatch is melt-spun, cooled with a draw ratio of 3.0, and heat-set at 120℃ to obtain plant-derived composite UV-resistant nylon filament.

[0037] The preparation method of functionalized lignin complex is as follows: Lignin nanoparticles were dispersed in anhydrous tetrahydrofuran and stirred at 400 rpm for 18 min under nitrogen to obtain a dispersion with a solid content of 6%. Triethylamine (1.1 times the molar amount of 2-furanoyl chloride) was added to the dispersion, and the mixture was cooled to 4 °C. Then, 2-furanoyl chloride (molar ratio of lignin hydroxyl groups to 2-furanoyl chloride was 1:0.2) was added dropwise over 20 min. After the addition was complete, the mixture was stirred at 4 °C for 30 min, then heated to 25 °C and stirred for another 5 h. After the reaction was completed, the mixture was filtered, washed three times with ethanol / water at a volume ratio of 1:1, and dried under vacuum at 45 °C for 16 h at a vacuum degree of 0.3 mbar to obtain a functionalized lignin complex (particle size of 100 nm).

[0038] Example 6: A method for preparing a plant-derived composite UV-resistant nylon filament, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 85 parts of nylon 6, 10 parts of functionalized lignin complex, 0.3 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl], and 0.5 parts of polyvinylpyrrolidone. S1.2. The above raw materials are dried in hot air at 85℃ for 5 hours, and then added to a twin-screw extruder for melt mixing at 235℃ and 200 rpm for 2 minutes. After extrusion, cooling and granulation, composite masterbatch is obtained. S1.3. The composite masterbatch is melt-spun, cooled with a draw ratio of 3.0, and heat-set at 120℃ to obtain plant-derived composite UV-resistant nylon filament.

[0039] The preparation method of functionalized lignin complex is as follows: Lignin nanoparticles were dispersed in anhydrous tetrahydrofuran and stirred at 400 rpm for 18 min under nitrogen to obtain a dispersion with a solid content of 6%. Triethylamine (1.1 times the molar amount of 2-furanoyl chloride) was added to the dispersion, and the mixture was cooled to 4 °C. Then, 2-furanoyl chloride (molar ratio of lignin hydroxyl groups to 2-furanoyl chloride was 1:0.2) was added dropwise over 20 min. After the addition was complete, the mixture was stirred at 4 °C for 30 min, then heated to 25 °C and stirred for another 5 h. After the reaction was completed, the mixture was filtered, washed three times with ethanol / water at a volume ratio of 1:1, and dried under vacuum at 45 °C for 16 h at a vacuum degree of 0.3 mbar to obtain a functionalized lignin complex (particle size of 100 nm).

[0040] Example 7: A method for preparing a plant-derived composite UV-resistant nylon filament, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 90 parts by weight of nylon 6, 8 parts by weight of functionalized lignin complex, 0.5 parts by weight of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl] pentaerythritol ester, and 1 part by weight of polyvinylpyrrolidone. S1.2. The above raw materials are dried in hot air at 90℃ for 6 hours, and then added to a twin-screw extruder for melt mixing at 235℃ and 300 rpm for 3 minutes. After extrusion, cooling and granulation, composite masterbatch is obtained. S1.3 The composite masterbatch is melt-spun, cooled with a draw ratio of 3.5 times, and heat-set at 130℃ to obtain plant-derived composite UV-resistant nylon filament.

[0041] The preparation method of functionalized lignin complex is as follows: Lignin nanoparticles were dispersed in anhydrous tetrahydrofuran and stirred at 600 rpm for 20 min under nitrogen to obtain a dispersion with a solid content of 10%. Triethylamine (1.2 times the molar amount of 2-furanoyl chloride) was added to the dispersion, and the mixture was cooled to 5 °C. Then, 2-furanoyl chloride (molar ratio of lignin hydroxyl groups to 2-furanoyl chloride was 1:0.2) was added dropwise over 30 min. After the addition was complete, the mixture was stirred at 5 °C for 30 min, then heated to 25 °C and stirred for another 6 h. After the reaction was completed, the mixture was filtered, washed three times with ethanol / water at a volume ratio of 1:1, and dried under vacuum at 50 °C for 24 h at a vacuum degree of 0.5 mbar to obtain a functionalized lignin complex (particle size of 200 nm).

[0042] Determination of UV protection performance and UV transmittance: A plain woven fabric sample (or the filaments bundled together into a flat sheet) was prepared using composite filaments, with a specification of 100×100mm, and the edges were sewn to prevent fraying; a UV-Vis spectrophotometer was used in conjunction with a professional UV transmittance / UPF tester, with a wavelength range of 280-400nm (UVB+UVA); the transmittance T(λ) of the sample to different wavelengths was measured according to the standard, and the UPF value was calculated (using the standard formula or the instrument's built-in calculation); the overall UV transmittance (%) was recorded.

[0043] Determination of mechanical properties (tensile strength and elongation at break of monofilament): Monofilaments were prepared according to the standard fiber filament test length (or the average of 20 bundled fibers, with at least 10 monofilaments per group); the fibers needed to be equilibrated in a standard environment (23±2℃, 50±5%RH) for 24 hours; the fibers were tested using a fiber tensile testing machine (with slit clamps), with a clamping distance of 20 mm and a loading rate of 20 mm·min⁻. 1 Record the fracture load and elongation, and calculate the fracture strength (MPa) and elongation at break (%) normalized to linear density.

[0044] Table 2 Performance data of plant-derived composite UV-resistant nylon filaments UV protection factor UV transmittance Fracture strength Elongation at break Example 4 25 6.0% 580MPa 28% Example 5 42 3.2% 560MPa 26% Example 6 56 1.6% 520MPa 24% As the content of functionalized lignin complex increased from 5 parts by weight to 10 parts by weight, the UPF increased significantly (from 25 to 56), while the UV transmittance decreased accordingly (from 6.0% to 1.6%). This indicates that functionalized lignin complex can effectively absorb / scatter UV light in fibers, and the higher the content, the stronger the protection.

[0045] The breaking strength and elongation of the monofilaments showed a slight decreasing trend with the increase of the content of functionalized lignin complex (breaking strength decreased from 580 to 520 MPa; breaking elongation decreased from 28 to 24%), indicating that high content of nanofillers can cause interfacial defects or microagglomeration, leading to stress concentration and thus reducing mechanical properties.

[0046] Comparative Example 1: The difference between this example and Example 4 is that lignin nanoparticles are used directly.

[0047] Comparative Example 2: The difference between this example and Example 4 is that no functionalized lignin complex was added.

[0048] Table 3 Performance data of plant-derived composite UV-resistant nylon filaments UV protection factor UV transmittance Fracture strength Elongation at break Example 4 25 6.0% 580MPa 28% Comparative Example 1 18 9.0% 560MPa 25% Comparative Example 2 8 22.0% 620MPa 31% Comparative Example 1 significantly reduced UV transmittance (UPF increased from 8 to 18), but the effect was not as good as that of functionalized products. This is because unmodified lignin nanoparticles tend to agglomerate in the masterbatch / fiber and have weak interfacial bonding, and the UV absorption sites are not fully dispersed and utilized.

[0049] In Comparative Example 2, the UPF was very low and the UV transmittance was high, reflecting that the nylon matrix itself had poor UV shielding ability.

[0050] Comparative Example 2 showed the highest fracture strength (620 MPa); the direct addition of lignin nanoparticles reduced the strength (560 MPa) due to stress concentration caused by agglomeration and weak interfaces.

[0051] The strength (580 MPa) of Example 4 is better than that of Comparative Example 1, indicating that coating or surface functionalization improves interfacial compatibility and reduces mechanical loss; the functionalized lignin complex maintains UV function while exhibiting minimal mechanical degradation (close to pure PA6).

[0052] The elongation at break decreased slightly with the increase of filler (fiber hardening, orientation and nanofiller affect elongation), but Example 4 had better retention (28%), which is beneficial to fabric processing and hand feel.

[0053] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A plant-derived composite UV-resistant nylon filament, characterized in that, The raw materials include: Nylon 6, functionalized lignin complex, tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl] pentaerythritol ester, and polyvinylpyrrolidone; The functionalized lignin complex is prepared by introducing furan functional groups on the surface of lignin nanoparticles to form a covalent structure.

2. The plant-derived composite UV-resistant nylon filament according to claim 1, characterized in that, The composition includes 80-90 parts by weight of nylon 6, 5-10 parts by weight of functionalized lignin complex, 0.1-0.5 parts by weight of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl] pentaerythritol ester, and 0.1-1 parts by weight of polyvinylpyrrolidone.

3. The plant-derived composite UV-resistant nylon filament according to claim 2, characterized in that, The preparation method of the functionalized lignin complex is as follows: Lignin nanoparticles were dispersed in anhydrous tetrahydrofuran and stirred at 300-600 rpm for 15-20 min under nitrogen to obtain a dispersion with a solid content of 5-10%. Triethylamine was added to the dispersion and cooled to 0-5℃. Then, 2-furanoyl chloride was added dropwise over a period of 10-30 min. After the addition was complete, the mixture was stirred at 0-5℃ for 30 min, then heated to 20-25℃ and stirred for another 4-6 h. After the reaction was completed, the mixture was filtered, washed 2-3 times with ethanol / water at a volume ratio of 1:1, and dried under vacuum to obtain the functionalized lignin complex.

4. The plant-derived composite UV-resistant nylon filament according to claim 3, characterized in that, The amount of triethylamine used is 1.0-1.2 times the molar amount of 2-furanoyl chloride.

5. The plant-derived composite UV-resistant nylon filament according to claim 3, characterized in that, The molar ratio of the lignin hydroxyl groups to 2-furanoyl chloride is 1:0.1-0.

3.

6. The plant-derived composite UV-resistant nylon filament according to claim 3, characterized in that, The vacuum drying temperature is 40-50℃, the vacuum degree is 0.1-0.5mbar, and the drying time is 12-24h.

7. The plant-derived composite UV-resistant nylon filament according to claim 3, characterized in that, The functionalized lignin complex has a particle size of 80-200 nm.

8. A method for preparing plant-derived composite UV-resistant functional nylon filament, used to prepare plant-derived composite UV-resistant functional nylon filament as described in any one of claims 1-7, characterized in that, The preparation method of the plant-derived composite UV-resistant nylon filament is as follows: S1.1 Weigh the following raw materials in parts by weight: 80-90 parts by weight of nylon 6, 5-10 parts by weight of functionalized lignin complex, 0.1-0.5 parts by weight of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)propyl] pentaerythritol ester, and 0.1-1 parts by weight of polyvinylpyrrolidone. S1.

2. Dry the above raw materials in hot air at 80-90℃ for 4-6 hours, then add them to a twin-screw extruder for melt mixing, hold for 1-3 minutes, extrude, cool and granulate to obtain composite masterbatch; S1.

3. The composite masterbatch is melt-spun to obtain plant-derived composite UV-resistant nylon filament.

9. The method for preparing plant-derived composite UV-resistant nylon filament according to claim 8, characterized in that, In S1.2, the twin-screw extruder temperature is 225-235℃ and the screw speed is 100-300rpm.

10. The method for preparing plant-derived composite UV-resistant nylon filament according to claim 8, characterized in that, In step S1.3, the cooling draw ratio is 2.5-3.5 times, and the heat setting temperature is 110-130℃.