Multifunctional polyester fiber and preparation method thereof

Abstract

The present invention relates to a multifunctional polyester fiber and a preparation method thereof, and belongs to the technical field of functional fibers. The preparation method comprises the following steps: S1, adding hydroxyapatite to a 4-carboxyphenylboric acid solution for ultrasonic treatment and heating reaction to obtain modified hydroxyapatite; S2, granulating the modified hydroxyapatite and polyester powder to obtain a multifunctional polyester masterbatch; S3, spinning the multifunctional polyester masterbatch and polyester slices to obtain a multifunctional polyester fiber. During the thermal decomposition process of the multifunctional polyester fiber, the generated phosphoric acid / polyphosphoric acid and boric acid can catalyze the decomposition of polyester, quickly generate a carbonized layer, and the generated calcium phosphate and boron-containing oxide have high thermal stability, promote the crosslinking and densification of the carbonized layer through a synergistic flame retardant effect, enhance the protective effect of the carbonized layer, prevent the melt flow of the polyester fiber, and inhibit the droplet phenomenon; in addition, the generated boron-containing oxide can capture free radicals in the combustion process, thereby reducing the generation of smoke particles.

Description

Technical Field

[0001] The invention belongs to the technical field of functional fibers, and in particular relates to a multifunctional polyester fiber and a preparation method thereof. Background Art

[0002] Polyester fiber is widely used in the field of textile materials due to its excellent mechanical properties, wrinkle resistance, easy cleaning, quick drying characteristics and good processing adaptability. However, its limiting oxygen index is only 20%, which is a flammable material. It is prone to melting droplets at high temperatures, increasing the risk of fire spread. In addition, the amount of smoke released is large, posing a threat to the safety of life and property, which has become a problem that needs to be solved urgently.

[0003] In order to improve the flame retardant properties, scholars have tried to introduce various types of nano flame retardants. Among them, hydroxyapatite, as an inorganic material with a wide range of sources and excellent performance, has attracted much attention because it is rich in phosphorus and calcium elements. Hydroxyapatite can enhance the flame retardant properties by accelerating the formation of the carbonization layer and increasing the amount of carbonization. At the same time, the presence of calcium ions can improve the anti-melting droplet characteristics and provide more comprehensive safety protection for polyester fibers. However, hydroxyapatite has poor compatibility with the polyester matrix, and direct blending may lead to a decrease in the mechanical properties of the fiber. Therefore, the modification technology that improves the compatibility of the two and achieves balanced performance has become the focus of current research.

[0004] Invention patent CN 104845025 A discloses a highly efficient modified ABS composite material using nano-hydroxyapatite loaded composite flame retardant and a preparation method thereof. During the preparation process of the composite material, nano-ATO, tricresyl phosphate, melamine cyanurate and other raw materials are used as environmentally friendly composite flame retardant synergists, and they are infiltrated and loaded into nano-hydroxyapatite under high pressure conditions, and then the flame retardant is added to the ABS material; however, nano-ATO, tricresyl phosphate, melamine cyanurate and other raw materials cannot be firmly bonded with nano-hydroxyapatite, and the flame retardant still has poor compatibility with polyester fibers, making it difficult to effectively improve the flame retardant properties of polyester fibers.

[0005] Zhu Yingke et al. (Effect of Hydroxyapatite on Flame Retardant Properties of Polypropylene. Engineering Plastics Application, 2014(6):1-6.) used hydroxyapatite as a synergistic flame retardant and prepared flame-retardant polypropylene composites by blending with an intumescent flame retardant (IFR, ammonium polyphosphate (APP) / pentaerythritol (PER) mass ratio of 3:1). However, these materials have poor compatibility with polypropylene and polyester, and their mechanical properties are particularly damaged by fibrous composites.

[0006] Wang Xiaomin et al. (Preparation of polylactic acid-based composite materials and study on their flame retardant properties. Tianjin: Tianjin University of Technology, 2019.) used ammonium polyphosphate, hydroxyapatite and nitrogen-containing organic matter N,N'-ethylenebis(12-hydroxystearamide) which can be used as a lubricant and dispersant to modify polylactic acid composites for flame retardancy. However, this process only uses simple blending, and it is difficult to produce a good combination between ammonium polyphosphate and hydroxyapatite. In addition, ammonium polyphosphate has poor compatibility with polyester fibers and a low thermal decomposition temperature, making it difficult to use melt blending technology for flame retardant modification of polyester fibers.

[0007] Therefore, it is of great significance to modify hydroxyapatite for the preparation of polyester fibers with flame retardant, anti-drip, smoke suppression and other properties. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a multifunctional polyester fiber and a preparation method thereof. First, 4-carboxyphenylboric acid is used to modify the surface of hydroxyapatite to obtain modified hydroxyapatite, and then the modified hydroxyapatite is used to prepare flame-retardant, anti-drip and smoke-suppressing polyester fiber by melt blending. On the one hand, the surface of hydroxyapatite is rich in calcium ions (Ca 2+ ), while the carboxylic acid group (-COOH) in the 4-carboxyphenylboronic acid molecule can bind to calcium ions through coordination to form a stable calcium-carboxylic acid complex; in addition, the boric acid group (-B(OH)2) in the 4-carboxyphenylboronic acid molecule can further bind to the hydroxyl group (-OH) on the surface of hydroxyapatite through hydrogen bonding or esterification reaction, so that the 4-carboxyphenylboronic acid molecule is firmly adsorbed on the surface of hydroxyapatite. On the other hand, the benzene ring structure in the 4-carboxyphenylboronic acid molecule interacts with the aromatic group in the polyester fiber molecule through π-π stacking, significantly enhancing the interfacial compatibility between the modified hydroxyapatite and the polyester fiber, thereby improving the dispersion performance of the modified hydroxyapatite in the polyester fiber. In addition, during the granulation and spinning stages, the 4-carboxyphenylboronic acid molecules on the surface of the modified hydroxyapatite can also melt, and will interact with the polyester chain at the interface through the π-π stacking of the aromatic ring, further improving the dispersibility and interfacial bonding strength.

[0009] The first object of the present invention is to provide a method for preparing a multifunctional polyester fiber, comprising the following steps:

[0010] S1, adding hydroxyapatite to a 4-carboxyphenylboric acid solution for ultrasonic treatment and heating reaction to obtain modified hydroxyapatite;

[0011] S2, granulating the modified hydroxyapatite and polyester powder described in S1 to obtain a multifunctional polyester masterbatch;

[0012] S3, spinning the multifunctional polyester masterbatch and polyester chips described in S2 to obtain the multifunctional polyester fiber.

[0013] In one embodiment of the present invention, in S1, the 4-carboxyphenylboric acid solution includes 4-carboxyphenylboric acid and ethanol; the mass fraction of 4-carboxyphenylboric acid in the 4-carboxyphenylboric acid solution is 15%-25%, 4-carboxyphenylboric acid is easily soluble in ethanol, and hydroxyapatite has good dispersibility in ethanol, which is conducive to the modification of hydroxyapatite by 4-carboxyphenylboric acid.

[0014] In one embodiment of the present invention, in S1, the mass ratio of 4-carboxyphenylboric acid to hydroxyapatite is 1:(2-3), and a small amount of 4-carboxyphenylboric acid is used to coat hydroxyapatite, so that the surface of hydroxyapatite is rich in aromatic benzene rings, thereby improving its compatibility with polyester fibers and its dispersion performance in polyester fibers.

[0015] In one embodiment of the present invention, in S1, the power of the ultrasonic treatment is 250W-500W, and the time is 30min-50min.

[0016] In one embodiment of the present invention, in S1, the heating reaction is carried out at a temperature of 50°C-60°C and for a time of 4h-6h.

[0017] In one embodiment of the present invention, before S2, the step of drying the modified hydroxyapatite and polyester powder is also included, the drying temperature of the modified hydroxyapatite is 70°C-80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, etc.; the drying time is 7h-9h, for example, it can be 7h, 8h, 9h, etc.; the drying temperature of the polyester powder is 125°C-135°C, for example, it can be 125°C, 126°C, 127°C, 128°C, 129°C, 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, etc.; the time is 10h-12h, for example, it can be 10h, 11h, 12h, etc.

[0018] In one embodiment of the present invention, in S2, the granulation is performed by melt blending, extrusion molding, cooling and pelletizing through a twin-screw extruder; the granulation temperature is 260°C-270°C. If the processing temperature is too low, the modified hydroxyapatite and polyester powder cannot be mixed evenly, which is not conducive to granulation. If the temperature is too high, it will cause energy waste.

[0019] In one embodiment of the present invention, in S2, the mass fraction of modified hydroxyapatite in the multifunctional polyester masterbatch is 20%-25%.

[0020] In one embodiment of the present invention, before S3, the step of drying the multifunctional polyester masterbatch and polyester chips is also included, and the drying is first pre-crystallized at 100°C-110°C for 3h-4h, and then dried at 125°C-135°C for 12h-14h to ensure that the final moisture content of the multifunctional polyester masterbatch and polyester chips is less than 100ppm.

[0021] In one embodiment of the present invention, in S3, the spinning is performed by a melt spinning machine, followed by oiling, pre-stretching, winding, and stretching after cooling; the spinning process parameters are: speed of 2000m / min-2500m / min, temperature of 265℃-275℃, and traction ratio of 1.5-2.5.

[0022] In one embodiment of the present invention, in S3, the mass fraction of the multifunctional polyester masterbatch in the multifunctional polyester fiber is 10%-15%.

[0023] The second object of the present invention is to provide a multifunctional polyester fiber prepared by the preparation method.

[0024] In one embodiment of the present invention, the limiting oxygen index of the multifunctional polyester fiber is 29.5%-30.9%, no droplets are generated, and the total smoke release is 0.38m 2 -0.45m 2 , breaking strength is not less than 3.1cN / dtex.

[0025] The technical solution of the present invention has the following advantages over the prior art:

[0026] (1) The preparation method of the present invention uses 4-carboxyphenylboronic acid to modify the surface of hydroxyapatite. On the one hand, the surface of hydroxyapatite is rich in calcium ions, and the carboxylic acid groups in the 4-carboxyphenylboronic acid molecules can combine with calcium ions through coordination to form a stable calcium-carboxylic acid complex; in addition, the boric acid groups in the 4-carboxyphenylboronic acid molecules can further combine with the hydroxyl groups on the surface of hydroxyapatite through hydrogen bonds or esterification reactions, so that the 4-carboxyphenylboronic acid molecules are firmly adsorbed on the surface of hydroxyapatite. On the other hand, the benzene ring structure in the 4-carboxyphenylboronic acid molecules interacts with the aromatic groups in the polyester fiber molecules through π-π stacking, significantly enhancing the interfacial compatibility between the modified hydroxyapatite and the polyester fiber, thereby improving the dispersion performance of the modified hydroxyapatite in the polyester fiber. In addition, during the granulation and spinning stages, the 4-carboxyphenylboronic acid molecules on the surface of the modified hydroxyapatite may also melt, and interact with the polyester chain at the interface through the π-π stacking of the aromatic ring, further improving the dispersibility and interfacial bonding strength.

[0027] (2) The hydroxyapatite in the multifunctional polyester fiber of the present invention is rich in phosphorus and calcium ions, and 4-carboxyphenylboric acid not only contains abundant boron, but also contains an aromatic carbon-forming agent with good thermal stability. During the thermal decomposition process, the generated phosphoric acid / polyphosphoric acid and boric acid can catalyze the decomposition of polyester and quickly generate a carbonized layer. The generated calcium phosphate and boron-containing oxide have high thermal stability, and promote the cross-linking and densification of the carbonized layer through the synergistic flame retardant effect, enhance the protective effect of the carbonized layer, prevent the melt flow of the polyester fiber, and inhibit the droplet phenomenon; in addition, the generated boron-containing oxide can capture free radicals in the combustion process, thereby reducing the generation of smoke particles. Therefore, the synergistic effect of the three can significantly improve the flame retardant, anti-droplet, and smoke suppression properties of polyester fibers, and improve the safety of polyester fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0029] Figure 1 This is a schematic diagram of the structure of the modified hydroxyapatite of Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0031] In the present invention, unless otherwise explained, technical and scientific terms used in the present invention have the same meanings as commonly understood by those skilled in the art to which the present invention belongs.

[0032] In the present invention, unless otherwise stated, the term "and / or" used in the present invention includes any and all combinations of one or more of the associated listed items.

[0033] In the present invention, unless otherwise stated, the experimental methods used in the embodiments of the present invention are conventional methods unless otherwise stated, and the materials, reagents, etc. used are all commercially available unless otherwise stated.

[0034] In the present invention, unless otherwise specified, the 4-carboxyphenylboric acid solution used in the examples of the present invention is prepared by dissolving 4-carboxyphenylboric acid in ethanol.

[0035] In the present invention, unless otherwise specified, the polyester powder and polyester chips used in the embodiments of the present invention are purchased from Yizheng Chemical Fiber with a brand name of FG650.

[0036] In the present invention, unless otherwise specified, the hydroxyapatite powder used in the examples of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a brand name of H684219 and a particle size of about 60 nm-80 nm. Example 1

[0037] The multifunctional polyester fiber and the preparation method thereof of the present embodiment specifically include the following steps:

[0038] S1. First, hydroxyapatite powder was slowly added into a 20% mass fraction 4-carboxyphenylboric acid solution, and then ultrasonically treated at 350W for 40min, and then the solution was heated to 55°C and stirred for 5h. Finally, the excess solvent was removed by rotary evaporation, and the modified hydroxyapatite was obtained after washing with deionized water and drying. Figure 1 ); wherein the mass ratio of 4-carboxyphenylboric acid to hydroxyapatite is 1:2.5;

[0039] S2, the modified hydroxyapatite was vacuum dried at 75°C for 8h; the polyester powder was vacuum dried at 130°C for 11h, and after mixing, it was melt blended, extruded, cooled and pelletized by a twin-screw extruder. The temperature of the twin-screw extruder was 265°C, and a multifunctional polyester masterbatch with a modified hydroxyapatite mass fraction of 23% was obtained;

[0040] S3, the multifunctional polyester masterbatch and the polyester chips were pre-crystallized in a 105°C blast oven for 3.5 hours, and then continued to be dried at 130°C for 13 hours, so that the final moisture content of the multifunctional polyester masterbatch and the polyester chips was less than 100 ppm. After mixing, they were spun by a melt spinning machine, cooled and oiled, pre-stretched, wound and stretched. The speed of the melt spinning machine was 2250 m / min, the temperature was 270°C, and the pulling ratio was 2, so as to obtain a multifunctional polyester fiber with a mass fraction of 13% of the multifunctional polyester masterbatch. Example 2

[0041] The multifunctional polyester fiber and the preparation method thereof of the present embodiment specifically include the following steps:

[0042] S1. First, hydroxyapatite powder is slowly added into a 15% mass fraction 4-carboxyphenylboric acid solution, and then ultrasonically treated at 250W for 50 minutes, and then the solution is heated to 50°C and stirred for 6 hours, and finally the excess solvent is removed by rotary evaporation, and the solution is washed with deionized water and dried to obtain modified hydroxyapatite; wherein the mass ratio of 4-carboxyphenylboric acid to hydroxyapatite is 1:2;

[0043] S2, the modified hydroxyapatite is vacuum dried at 70°C for 9h; the polyester powder is vacuum dried at 125°C for 12h, and after mixing, it is melt-blended, extruded, cooled and pelletized by a twin-screw extruder, and the temperature of the twin-screw extruder is 260°C to obtain a multifunctional polyester masterbatch with a modified hydroxyapatite mass fraction of 20%;

[0044] S3, the multifunctional polyester masterbatch and the polyester chips were pre-crystallized in a 100°C blast oven for 4 hours, and then dried at 125°C for 14 hours to make the final moisture content of the multifunctional polyester masterbatch and the polyester chips less than 100 ppm. After mixing, they were spun through a melt spinning machine, cooled and oiled, pre-stretched, wound and stretched. The speed of the melt spinning machine was 2000 m / min, the temperature was 265°C, and the pulling ratio was 1.5, to obtain a multifunctional polyester fiber with a mass fraction of 10% of the multifunctional polyester masterbatch. Example 3

[0045] The multifunctional polyester fiber and the preparation method thereof of the present embodiment specifically include the following steps:

[0046] S1. First, hydroxyapatite powder is slowly added into a 25% by mass 4-carboxyphenylboric acid solution, and then ultrasonically treated at 500W for 30 minutes, and then the solution is heated to 60°C and stirred for 4 hours, and finally the excess solvent is removed by rotary evaporation, and the solution is washed with deionized water and dried to obtain modified hydroxyapatite; wherein the mass ratio of 4-carboxyphenylboric acid to hydroxyapatite is 1:3;

[0047] S2, the modified hydroxyapatite is vacuum dried at 80°C for 7h; the polyester powder is vacuum dried at 135°C for 10h, and after mixing, it is melt-blended, extruded, cooled and pelletized by a twin-screw extruder, and the temperature of the twin-screw extruder is 270°C to obtain a multifunctional polyester masterbatch with a modified hydroxyapatite mass fraction of 25%;

[0048] S3, the multifunctional polyester masterbatch and the polyester chips were pre-crystallized in a 110°C blast oven for 3 hours, and then dried at 135°C for 12 hours to make the final moisture content of the multifunctional polyester masterbatch and the polyester chips less than 100 ppm. After mixing, they were spun through a melt spinning machine, cooled and oiled, pre-stretched, wound and stretched. The speed of the melt spinning machine was 2500 m / min, the temperature was 275°C, and the pulling ratio was 2.5, to obtain a multifunctional polyester fiber with a mass fraction of 15% of the multifunctional polyester masterbatch. Comparative Example 1

[0049] Basically the same as Example 1, except that 4-carboxyphenylboronic acid is replaced by boric acid. Comparative Example 2

[0050] The same as Example 1, except that 4-carboxyphenylboronic acid is replaced by benzoic acid. Comparative Example 3

[0051] The method is basically the same as Example 1, except that 4-carboxyphenylboronic acid is not used for modification. Comparative Example 4

[0052] Basically the same as Example 1, except that hydroxyapatite is replaced by calcium carbonate. Comparative Example 5

[0053] Basically the same as Example 1, except that hydroxyapatite is replaced by calcium hydroxide. Comparative Example 6

[0054] The method is basically the same as Example 1, except that modified hydroxyapatite is not used for modification.

[0055] Test Case

[0056] The physical properties of the multifunctional polyester fibers (modified polyester fibers) and unmodified polyester fibers prepared in Examples 1-3 and Comparative Examples 1-6 were tested:

[0057] Limiting oxygen index: Refer to FZ / T 50017-2011 "Test method for flame retardancy of polyester fiber - oxygen index method" to test the limiting oxygen index of modified polyester fiber and unmodified polyester fiber;

[0058] Burning test: Refer to the UL94 vertical burning standard to test the droplet generation of modified polyester fiber and unmodified polyester fiber;

[0059] Smoke release performance: Refer to ISO 5660-1:2015 "Heat Release Rate Test Standard" to test the total smoke release of modified polyester fiber and unmodified polyester fiber;

[0060] Breaking strength: Refer to GB / T 14344-2022 "Test method for tensile properties of chemical fiber filaments" to test the breaking strength of modified polyester fiber and unmodified polyester fiber;

[0061] Table 1 shows the relevant properties of the unmodified polyester fiber and the modified polyester fiber finally measured:

[0062] Table 1

[0063]

[0064] As can be seen from Table 1, the modified polyester fiber has a higher limiting oxygen index, no droplet generation, better flame retardancy, reduced smoke release, and higher breaking strength, indicating that the modified hydroxyapatite and polyester fiber have good compatibility.

[0065] By comparing Example 1 and Comparative Example 1, it can be seen that when 4-carboxyphenylboric acid is replaced by boric acid, the flame retardant properties of the modified polyester fiber are reduced, no molten droplets are generated, smoke release is increased, and the breaking strength is significantly reduced. This is because the boric acid coated on the surface of hydroxyapatite has poor compatibility with the polyester fiber, making it difficult for the modified hydroxyapatite to be evenly dispersed in the polyester fiber.

[0066] By comparing Example 1 and Comparative Example 2, it can be seen that when 4-carboxyphenylboronic acid is replaced by benzoic acid, the flame retardant performance of the modified polyester fiber is reduced, molten droplets are generated, smoke release increases, and the breaking strength decreases. This is because the flame retardant efficiency of benzoic acid is low and it cannot produce a synergistic flame retardant effect with hydroxyapatite.

[0067] By comparing Example 1 and Comparative Example 3, it can be seen that when 4-carboxyphenylboric acid is not used for modification, hydroxyapatite is difficult to be uniformly dispersed in the polyester fiber, resulting in significant damage to the mechanical properties of the polyester fiber, reduced flame retardant properties, and significantly increased smoke release.

[0068] By comparing Example 1 and Comparative Example 4, it can be seen that when hydroxyapatite is replaced by calcium carbonate, the flame retardant performance of the modified polyester fiber is reduced, molten droplets are generated, smoke release increases, and breaking strength decreases. This is because the flame retardant efficiency of calcium carbonate is much lower than that of hydroxyapatite.

[0069] By comparing Example 1 and Comparative Example 5, it can be seen that when hydroxyapatite is replaced by calcium hydroxide, the flame retardant performance of the modified polyester fiber is reduced, molten droplets are generated, smoke release is increased, and breaking strength is reduced. This is because the flame retardant efficiency of calcium hydroxide is much lower than that of hydroxyapatite.

[0070] By comparing Example 1 and Comparative Example 6, it can be seen that the polyester fiber without flame retardant modification has poor flame retardant properties, high smoke release and poor fire safety.

[0071] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for preparing a multifunctional polyester fiber, characterized in that: The following steps are involved: S1, adding hydroxyapatite to a 4-carboxyphenylboric acid solution for ultrasonic treatment and heating reaction to obtain modified hydroxyapatite; S2, granulating the modified hydroxyapatite and polyester powder described in S1 to obtain a multifunctional polyester masterbatch; S3, spinning the multifunctional polyester masterbatch and polyester chips described in S2 to obtain the multifunctional polyester fiber.

2. The method for preparing the multifunctional polyester fiber according to claim 1, characterized in that: In S1, the 4-carboxyphenylboric acid solution comprises 4-carboxyphenylboric acid and ethanol; the mass fraction of 4-carboxyphenylboric acid in the 4-carboxyphenylboric acid solution is 15%-25%.

3. The method for preparing the multifunctional polyester fiber according to claim 1, characterized in that: In S1, the mass ratio of 4-carboxyphenylboronic acid to hydroxyapatite is 1:(2-3).

4. The method for preparing the multifunctional polyester fiber according to claim 1, characterized in that: In S1, the power of the ultrasonic treatment is 250W-500W, and the time is 30min-50min.

5. The method for preparing the multifunctional polyester fiber according to claim 1, characterized in that: In S1, the heating reaction is carried out at a temperature of 50°C-60°C and for a time of 4h-6h.

6. The method for preparing the multifunctional polyester fiber according to claim 1, characterized in that: In S2, the granulation is performed by melt blending, extrusion molding, cooling and pelletizing through a twin-screw extruder; the granulation temperature is 260°C-270°C.

7. The method for preparing the multifunctional polyester fiber according to claim 1, characterized in that: In S2, the mass fraction of modified hydroxyapatite in the multifunctional polyester masterbatch is 20%-25%.

8. The method for preparing the multifunctional polyester fiber according to claim 1, characterized in that: In S3, the spinning is carried out by a melt spinning machine, followed by oiling after cooling, pre-stretching, winding, and stretching; the spinning process parameters are: speed of 2000m / min-2500m / min, temperature of 265℃-275℃, and traction ratio of 1.5-2.

5.

9. The method for preparing the multifunctional polyester fiber according to claim 1, characterized in that: In S3, the mass fraction of the multifunctional polyester masterbatch in the multifunctional polyester fiber is 10%-15%.

10. The multifunctional polyester fiber prepared by the preparation method according to any one of claims 1 to 9.

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