Polylactic acid fiber as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of polylactic acid fiber production, and provides a polylactic acid fiber and a preparation method and application thereof, the polylactic acid fiber comprises the following raw materials by weight: 65-80 parts of polylactic acid, 0.5-3 parts of a nucleating agent, 0.05-0.2 part of a lubricant, and 0.05-0.1 part of an antioxidant; the preparation method of the nucleating agent comprises the following steps: adding montmorillonite into deionized water, carrying out ultrasonic dispersion, adding modified chitosan, heating to 75-80 DEG C, continuing to stir and react for 4-6 hours, and after the reaction is finished, filtering, washing, drying and grinding to obtain the nucleating agent. The polylactic acid fiber prepared by the invention has the advantages of excellent crystallization property, mechanical property, flexibility, heat resistance and the like, is a high-performance and environment-friendly fiber material, and can be widely applied to the fields of fashion, sports goods, hygienic products and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of polylactic acid fiber production, and in particular relates to polylactic acid fiber and a preparation method and application thereof. Background Art

[0002] With the continuous improvement of people's living standards and the strengthening of social environmental awareness, safer and more environmentally friendly materials are gaining increasing attention. Polylactic acid (PLA) is one of the most typical non-petroleum-based materials. It is derived from plants, and is produced by fermenting plant starches such as corn starch and cassava starch to produce lactic acid, which is then further synthesized. PLA fiber is made from plants. When discarded in soil or seawater, its products can be decomposed into carbon dioxide and water by microorganisms. It does not emit toxic gases and cause environmental pollution when burned. From raw materials to waste, it can be recycled and reused, without any harm to the environment. It is a sustainable and green fiber.

[0003] Polylactic acid (PLA) fiber embodies the advantages of both natural and synthetic fibers while overcoming some of their shortcomings. For example, it possesses the biodegradability, moisture absorption, breathability, and comfort characteristics of natural fibers, while also possessing numerous excellent properties, such as inherent flame retardancy and resistance to bacterial growth. Due to these excellent combined properties, PLA fiber holds enormous potential for application in the textile industry. In recent years, its development has attracted significant attention from industry professionals, with applications in home textiles, clothing, nonwovens, filter materials, sanitary products, automotive interiors, and furniture coverings. However, while PLA is a crystalline polymer, it has only one methylene carbon atom between the ester groups in the main chain, resulting in a helical molecular structure. This restricts chain mobility and results in a very slow crystallization rate, making PLA fiber less resistant to high temperatures. Furthermore, PLA is hard and brittle, resulting in insufficient fiber toughness and softness. Consequently, PLA's further development is hampered by its shortcomings, such as a slow crystallization rate, low mechanical strength, and insufficient heat resistance.

[0004] Therefore, how to prepare a polylactic acid fiber with excellent heat resistance, crystallization and mechanical properties is one of the problems that urgently needs to be solved. Summary of the Invention

[0005] The object of the present invention is to provide a polylactic acid fiber and a preparation method and application thereof, so as to solve the problem of poor crystallization performance of polylactic acid fiber in the prior art.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] The first aspect of the present invention provides a polylactic acid fiber, comprising the following raw materials in parts by weight:

[0008] 65-80 parts of polylactic acid, 0.5-3 parts of nucleating agent, 0.05-0.2 parts of lubricant, and 0.05-0.1 parts of antioxidant; the preparation steps of the nucleating agent are as follows:

[0009] Montmorillonite is added to deionized water and ultrasonically dispersed, and modified chitosan is added. The temperature is raised to 75-80° C. and the mixture is stirred and reacted for 4-6 hours. After the reaction is completed, the mixture is filtered, washed, dried, and ground to obtain a nucleating agent.

[0010] As a preferred embodiment of the present invention, the usage ratio of montmorillonite, deionized water and modified chitosan is 3-5 g:100 mL:1.8-3.0 g.

[0011] As a preferred embodiment of the present invention, the preparation steps of the modified chitosan are as follows:

[0012] Chitosan and 2,3-epoxypropyltrimethylammonium chloride were added to isopropanol and stirred at 75-80°C for 9-10 hours. After the reaction, the mixture was filtered under reduced pressure, washed, and dried under vacuum to obtain modified chitosan. The chitosan, 2,3-epoxypropyltrimethylammonium chloride, and isopropanol were used in a ratio of 4.0-4.5 g:10-11 mL:50 mL. The reaction of chitosan and 2,3-epoxypropyltrimethylammonium chloride introduces quaternary ammonium groups through ring-opening polymerization, significantly improving the water solubility and functionality of the chitosan.

[0013] In a preferred embodiment of the present invention, the lubricant is one of polyoxyethylene wax, fatty alcohol polyoxyethylene ether, and ethylene bisstearamide. The addition of the lubricant can reduce melt flow resistance, improve melt fluidity, enhance polylactic acid fiber processing efficiency, reduce friction and wear, extend mold life, and thereby reduce maintenance costs and increase production speed.

[0014] As a preferred embodiment of the present invention, the antioxidant is one of antioxidant 1010, antioxidant 168, antioxidant 1098, and TPH-24. The addition of the antioxidant can not only effectively inhibit the degradation of polylactic acid during the melt spinning process, but also improve the antioxidant properties of polylactic acid fiber and its mechanical properties and thermal stability.

[0015] A second aspect of the present invention provides a method for preparing polylactic acid fiber, comprising the following steps:

[0016] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0017] S2, putting the mixture obtained in S1 into a twin-screw extruder for granulation, drying, and obtaining masterbatch;

[0018] S3. The masterbatch obtained in S2 is melt-spun, wound, and drawn in a spinning machine to obtain polylactic acid fibers.

[0019] As a preferred embodiment of the present invention, the temperature of each zone in the twin-screw extruder in S2 is 180-210° C., and the screw speed is 200-300 r / min.

[0020] As a preferred embodiment of the present invention, the melt spinning temperature in S3 is 200-250°C, and the winding speed is 1000-2000 m / min. When the melt spinning temperature is lower than 200°C, the melt fluidity is low and the spinnability is poor. When the melt spinning temperature is higher than 250°C, the melt is likely to degrade severely, making normal spinning impossible.

[0021] As a preferred embodiment of the present invention, the stretching temperature in the stretching process in S3 is 70-110° C., and the stretching ratio is 2-4 times.

[0022] The third aspect of the present invention provides the use of the polylactic acid fiber described in the first aspect and the polylactic acid fiber obtained by the preparation method of the polylactic acid fiber described in the second aspect in fashion, sporting goods and sanitary products.

[0023] Beneficial effects of the present invention:

[0024] The polylactic acid fiber provided by the present invention is prepared by mixing polylactic acid, a nucleating agent, a lubricant and an antioxidant in a reasonable proportion, extruding and granulating through a twin-screw extruder, and then melt-spinning and stretching to obtain the polylactic acid fiber. The prepared polylactic acid fiber has the advantages of excellent crystallization properties, mechanical properties, flexibility, heat resistance, etc. It is a high-performance, environmentally friendly fiber material that can be widely used in the fields of fashion, sporting goods, sanitary products, etc.

[0025] The nucleating agent added to the polylactic acid fiber raw material of the present invention, montmorillonite, as a crystallization nucleating agent, can promote the crystallization of polylactic acid, increase the crystallization rate, and then improve the heat resistance of polylactic acid fiber, so that some products obtained from polylactic acid fiber will not deform during high-temperature ironing. However, the dispersion performance and interfacial compatibility of montmorillonite in polylactic acid are relatively poor. Therefore, when adding montmorillonite to improve the crystallization performance of polylactic acid, the mechanical properties of polylactic acid fiber material are reduced. Therefore, the present invention adopts modified chitosan to carry out organic intercalation modification on montmorillonite to improve the dispersion performance of montmorillonite. The modified chitosan is inserted into the lamellar montmorillonite, so that the interlayer spacing of the modified montmorillonite is increased, resulting in the montmorillonite after intercalation being able to be evenly dispersed in polylactic acid. In addition, the addition of modified montmorillonite improves the mechanical properties of polylactic acid to a certain extent, and the tensile strength, elongation at break and impact strength of polylactic acid are improved to varying degrees.

[0026] The invention provides a preparation method of polylactic acid fiber, which has a simple process flow, an environmentally friendly production process, readily available raw materials, low cost, and is conducive to industrial production. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] Example 1

[0029] This embodiment provides a polylactic acid fiber and a preparation method thereof:

[0030] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0031] 65 parts of polylactic acid, 0.5 parts of nucleating agent, 0.05 parts of polyoxyethylene wax, and 0.05 parts of antioxidant 1010;

[0032] The preparation steps of the nucleating agent are as follows:

[0033] 4.0 g of chitosan and 10 mL of 2,3-epoxypropyltrimethylammonium chloride were added to 50 mL of isopropanol, heated to 80°C and stirred for reaction for 10 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed, and dried in a vacuum drying oven at 55°C for 24 h to obtain modified chitosan.

[0034] 3 g of montmorillonite was added to 100 mL of deionized water and ultrasonically dispersed for 30 min. 1.8 g of modified chitosan was added and the temperature was raised to 80 °C and stirred for 6 h. After the reaction was completed, the mixture was filtered and repeatedly washed with deionized water until no white precipitate was found when tested with 0.05 mol / L AgNO3 solution. Finally, the mixture was dried in an oven at 80 °C for 24 h and ground to obtain a nucleating agent.

[0035] The specific preparation steps of the above-mentioned preparation method of polylactic cellulose are as follows:

[0036] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0037] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 180° C. and the screw speed is 300 r / min. The mixture is dried to obtain a masterbatch.

[0038] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200° C. and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 70° C. and a stretching ratio of 4 to obtain polylactic acid fiber.

[0039] Example 2

[0040] Compared with Example 1, the only difference is that the preparation of the nucleating agent is different:

[0041] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0042] 65 parts of polylactic acid, 0.5 parts of nucleating agent, 0.05 parts of polyoxyethylene wax, and 0.05 parts of antioxidant 1010;

[0043] The preparation steps of the nucleating agent are as follows:

[0044] 4.0 g of chitosan and 10 mL of 2,3-epoxypropyltrimethylammonium chloride were added to 50 mL of isopropanol, heated to 80°C and stirred for reaction for 10 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed, and dried in a vacuum drying oven at 55°C for 24 h to obtain modified chitosan.

[0045] 5 g of montmorillonite was added to 100 mL of deionized water and ultrasonically dispersed for 30 min. 3.0 g of modified chitosan was added and the temperature was raised to 80 °C and stirred for 6 h. After the reaction was completed, the mixture was filtered and repeatedly washed with deionized water until no white precipitate was found when tested with 0.05 mol / L AgNO3 solution. Finally, the mixture was dried in an oven at 80 °C for 24 h and ground to obtain a nucleating agent.

[0046] The specific preparation steps of the above-mentioned preparation method of polylactic cellulose are as follows:

[0047] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0048] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 180° C. and the screw speed is 300 r / min. The mixture is dried to obtain a masterbatch.

[0049] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200° C. and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 70° C. and a stretching ratio of 4 to obtain polylactic acid fiber.

[0050] Example 3

[0051] Compared with Example 1, the only difference is that the preparation of the nucleating agent is different:

[0052] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0053] 65 parts of polylactic acid, 0.5 parts of nucleating agent, 0.05 parts of polyoxyethylene wax, and 0.05 parts of antioxidant 1010;

[0054] The preparation steps of the nucleating agent are as follows:

[0055] 4.5 g of chitosan and 11 mL of 2,3-epoxypropyltrimethylammonium chloride were added to 50 mL of isopropanol, heated to 80°C and stirred for reaction for 10 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed, and dried in a vacuum drying oven at 55°C for 24 h to obtain modified chitosan.

[0056] 3 g of montmorillonite was added to 100 mL of deionized water and ultrasonically dispersed for 30 min. 1.8 g of modified chitosan was added and the temperature was raised to 80 °C and stirred for 6 h. After the reaction was completed, the mixture was filtered and repeatedly washed with deionized water until no white precipitate was found when tested with 0.05 mol / L AgNO3 solution. Finally, the mixture was dried in an oven at 80 °C for 24 h and ground to obtain a nucleating agent.

[0057] The specific preparation steps of the above-mentioned preparation method of polylactic cellulose are as follows:

[0058] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0059] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 180° C. and the screw speed is 300 r / min. The mixture is dried to obtain a masterbatch.

[0060] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200° C. and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 70° C. and a stretching ratio of 4 to obtain polylactic acid fiber.

[0061] Example 4

[0062] Compared with Example 1, the only difference is that the amount of polylactic acid fiber raw material is different:

[0063] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0064] 80 parts of polylactic acid, 2.5 parts of nucleating agent, 0.1 parts of polyoxyethylene wax, 10100.06 parts of antioxidant;

[0065] The specific preparation steps of the above-mentioned preparation method of polylactic cellulose are as follows:

[0066] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0067] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 180° C. and the screw speed is 300 r / min. The mixture is dried to obtain a masterbatch.

[0068] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200° C. and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 70° C. and a stretching ratio of 4 to obtain polylactic acid fiber.

[0069] Example 5

[0070] Compared with Example 1, the only difference is that the amount of polylactic acid fiber raw material is different:

[0071] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0072] 700 parts of polylactic acid, 1.8 parts of nucleating agent, 0.15 parts of polyoxyethylene wax, 0.08 parts of antioxidant 1010;

[0073] The specific preparation steps of the above-mentioned preparation method of polylactic cellulose are as follows:

[0074] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0075] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 180° C. and the screw speed is 300 r / min. The mixture is dried to obtain a masterbatch.

[0076] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200° C. and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 70° C. and a stretching ratio of 4 to obtain polylactic acid fiber.

[0077] Example 6

[0078] Compared with Example 1, the only difference is that step S2 in the preparation method of polylactic acid fiber is different:

[0079] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0080] 65 parts of polylactic acid, 0.5 parts of nucleating agent, 0.05 parts of polyoxyethylene wax, and 0.05 parts of antioxidant 1010;

[0081] The specific preparation steps of a preparation method of polylactic acid cellulose are as follows:

[0082] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0083] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 200° C. and the screw speed is 300 r / min. The mixture is dried to obtain a masterbatch.

[0084] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200° C. and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 70° C. and a stretching ratio of 4 to obtain polylactic acid fiber.

[0085] Example 7

[0086] Compared with Example 1, the only difference is that step S2 in the preparation method of polylactic acid fiber is different:

[0087] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0088] 65 parts of polylactic acid, 0.5 parts of nucleating agent, 0.05 parts of polyoxyethylene wax, and 0.05 parts of antioxidant 1010;

[0089] The specific preparation steps of a preparation method of polylactic acid cellulose are as follows:

[0090] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0091] S2, putting the mixture obtained in S1 into a twin-screw extruder for granulation, with the temperature of each zone in the twin-screw extruder being 180°C and the screw speed being 250 r / min, and drying to obtain masterbatch;

[0092] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200° C. and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 70° C. and a stretching ratio of 4 to obtain polylactic acid fiber.

[0093] Example 8

[0094] Compared with Example 1, the only difference is that step S3 in the preparation method of polylactic acid fiber is different:

[0095] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0096] 65 parts of polylactic acid, 0.5 parts of nucleating agent, 0.05 parts of polyoxyethylene wax, and 0.05 parts of antioxidant 1010;

[0097] The specific preparation steps of a preparation method of polylactic acid cellulose are as follows:

[0098] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0099] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 180° C. and the screw speed is 300 r / min. The mixture is dried to obtain a masterbatch.

[0100] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 245°C and a winding speed of 1500 m / min. The fiber is wound and stretched at a stretching temperature of 70°C and a stretching ratio of 4 to obtain polylactic acid fiber.

[0101] Example 9

[0102] Compared with Example 1, the only difference is that step S3 in the preparation method of polylactic acid fiber is different:

[0103] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0104] 65 parts of polylactic acid, 0.5 parts of nucleating agent, 0.05 parts of polyoxyethylene wax, and 0.05 parts of antioxidant 1010;

[0105] The specific preparation steps of a preparation method of polylactic acid cellulose are as follows:

[0106] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0107] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 180° C. and the screw speed is 300 r / min. The mixture is dried to obtain a masterbatch.

[0108] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200° C. and a winding speed of 1000 m / min. The fiber is wound and drawn at a drawing temperature of 100° C. and a drawing ratio of 2 to obtain polylactic acid fiber.

[0109] Comparative Example 1

[0110] Compared with Example 1, the only difference is that no nucleating agent is added to the polylactic acid raw material:

[0111] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0112] 65 parts of polylactic acid, 0.05 parts of polyoxyethylene wax, 10100.05 parts of antioxidant;

[0113] The specific preparation steps of the above-mentioned preparation method of polylactic cellulose are as follows:

[0114] S1, adding polylactic acid, lubricant and antioxidant into a high-speed mixer according to a proportion and mixing until uniform to obtain a mixture;

[0115] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 180° C. and the screw speed is 300 r / min. The mixture is dried to obtain a masterbatch.

[0116] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200° C. and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 70° C. and a stretching ratio of 4 to obtain polylactic acid fiber.

[0117] Comparative Example 2

[0118] Compared with Example 1, the only difference is that the nucleating agent in the polylactic acid fiber raw material is montmorillonite:

[0119] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0120] 65 parts of polylactic acid, 0.5 parts of montmorillonite, 0.05 parts of polyoxyethylene wax, and 0.05 parts of antioxidant 1010;

[0121] The specific preparation steps of the above-mentioned preparation method of polylactic cellulose are as follows:

[0122] S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture;

[0123] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 180° C. and the screw speed is 300 r / min. The mixture is dried to obtain a masterbatch.

[0124] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200° C. and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 70° C. and a stretching ratio of 4 to obtain polylactic acid fiber.

[0125] Comparative Example 3

[0126] Compared with Example 1, the only difference is that the amount of polylactic acid fiber raw material is different:

[0127] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0128] 55 parts of polylactic acid, 0.5 parts of nucleating agent, 0.05 parts of polyoxyethylene wax, and 0.05 parts of antioxidant 1010.

[0129] Comparative Example 4

[0130] Compared with Example 1, the only difference is that the amount of polylactic acid fiber raw material is different:

[0131] A polylactic acid fiber, comprising the following raw materials in parts by weight:

[0132] 65 parts of polylactic acid, 0.3 parts of nucleating agent, 0.05 parts of polyoxyethylene wax, and 0.05 parts of antioxidant 1010.

[0133] Comparative Example 5

[0134] Compared with Example 1, the only difference is that step S2 in the preparation method of polylactic acid fiber is different:

[0135] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 180° C. and the screw speed is 150 r / min. The mixture is dried to obtain masterbatch.

[0136] Comparative Example 6

[0137] Compared with Example 1, the only difference is that step S2 in the preparation method of polylactic acid fiber is different:

[0138] S2. The mixture obtained in S1 is put into a twin-screw extruder for granulation. The temperature of each zone in the twin-screw extruder is 160° C. and the screw speed is 300 r / min. The mixture is dried to obtain masterbatch.

[0139] Comparative Example 7

[0140] Compared with Example 1, the only difference is that step S3 in the preparation method of polylactic acid fiber is different:

[0141] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 180°C and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 70°C and a stretching ratio of 4 to obtain polylactic acid fiber.

[0142] Comparative Example 8

[0143] Compared with Example 1, the only difference is that step S3 in the preparation method of polylactic acid fiber is different:

[0144] S3. The masterbatch obtained in S2 is melt-spun in a spinning machine at a melt spinning temperature of 200°C and a winding speed of 1000 m / min. The fiber is wound and stretched at a stretching temperature of 60°C and a stretching ratio of 4 times to obtain polylactic acid fiber.

[0145] The polylactic acid fibers obtained in Examples 1-9 and Comparative Examples 1-8 were subjected to performance testing according to the standard GB / T 14337-2008, "Test Method for Tensile Properties of Chemical Staple Fibers." Fiber strength was measured at a tensile speed of 20 mm / min, with a fiber clamping length of 20 m. Each test result was calculated as the arithmetic mean of 20 fibers. Hot water shrinkage was measured using an electron beam irradiation dose of 200 kGy to test the hot water shrinkage of the irradiated polylactic acid fiber composites. The test results are shown in Table 1.

[0146] Table 1

[0147]

[0148] As can be seen from the data in Table 1, the polylactic acid fibers prepared in Examples 1-9 have superior tensile strength, elongation at break, and heat resistance compared to the polylactic acid fibers obtained in Comparative Examples 1-8. Thus, the polylactic acid fibers and preparation methods provided by the present invention have excellent crystallization properties, mechanical properties, flexibility, heat resistance, and other advantages. These fibers are high-performance, environmentally friendly fiber materials that can be widely used in fields such as fashion, sporting goods, and sanitary products.

[0149] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0150] It should be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution. Some or all steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of this application.

[0151] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0152] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution, and all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0153] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A polylactic acid fiber, characterized in that Calculated by weight, it includes the following raw materials: 65-80 parts of polylactic acid, 0.5-3 parts of nucleating agent, 0.05-0.2 parts of lubricant, and 0.05-0.1 parts of antioxidant; the preparation steps of the nucleating agent are as follows: Add montmorillonite into deionized water, disperse it by ultrasonic, add modified chitosan, raise the temperature to 75-80°C and continue stirring to react for 4-6 hours. After the reaction is completed, filter, wash, dry and grind to obtain a nucleating agent.

2. The polylactic acid fiber according to claim 1, characterized in that: The usage ratio of montmorillonite, deionized water and modified chitosan is 3-5 g:100 mL:1.8-3.0 g.

3. The polylactic acid fiber according to claim 1, characterized in that: The preparation steps of the modified chitosan are as follows: Chitosan and 2,3-epoxypropyltrimethylammonium chloride are added to isopropanol, the temperature is raised to 75-80°C, and the mixture is stirred and reacted for 9-10 hours. After the reaction, the mixture is filtered under reduced pressure, washed, and vacuum dried to obtain modified chitosan; wherein the amount ratio of chitosan, 2,3-epoxypropyltrimethylammonium chloride, and isopropanol is 4.0-4.5 g: 10-11 mL: 50 mL.

4. The polylactic acid fiber according to claim 1, characterized in that: The lubricant is one of polyoxyethylene wax, fatty alcohol polyoxyethylene ether and ethylene bisstearamide.

5. The polylactic acid fiber according to claim 1, characterized in that: The antioxidant is one of antioxidant 1010, antioxidant 168, antioxidant 1098 and TPH-24.

6. The method for preparing polylactic acid fiber according to claim 5, characterized in that: The following steps are involved: S1. Adding polylactic acid, a nucleating agent, a lubricant, and an antioxidant into a high-speed mixer according to a proportion and mixing them until uniform to obtain a mixture; S2, putting the mixture obtained in S1 into a twin-screw extruder for granulation, drying, and obtaining masterbatch; S3. The masterbatch obtained in S2 is melt-spun, wound, and drawn in a spinning machine to obtain polylactic acid fibers.

7. The method for preparing polylactic acid fiber according to claim 6, characterized in that: The temperature of each zone in the twin-screw extruder S2 is 180-210°C, and the screw speed is 200-300r / min.

8. The method for preparing polylactic acid fiber according to claim 6, characterized in that: The melt spinning temperature in S3 is 200-250°C, and the winding speed is 1000-2000 m / min.

9. The method for preparing polylactic acid fiber according to claim 6, characterized in that: The drawing temperature of the drawing process in S3 is 70-110° C., and the drawing ratio is 2-4 times.

10. Use of the polylactic acid fiber according to any one of claims 1 to 5, or the polylactic acid fiber obtained by the preparation method of the polylactic acid fiber according to any one of claims 6 to 9, in fashion, sporting goods and sanitary products.

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