Antibacterial elastic polyester fiber and preparation method thereof

Abstract

The invention relates to the technical field of polyester fiber preparation, in particular to antibacterial elastic polyester fiber and a preparation method thereof.The antibacterial elastic polyester fiber is prepared from, by weight, 95-105 parts of modified polyester, 5-9 parts of antibacterial agent, 0.5-1.5 parts of flame retardant and 0.5-1 part of antioxidant. The antibacterial elastic polyester fiber prepared by the invention has good antibacterial performance and rebound resilience.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester fiber preparation, and specifically relates to an antibacterial elastic polyester fiber and a preparation method thereof. Background Art

[0002] Polyester fiber, commonly known as terylene, is a type of synthetic fiber made from terephthalic acid and ethylene glycol through esterification or transesterification and polycondensation reactions to form a high molecular compound, and then obtained through spinning and post-treatment. It is widely used in making clothing, home textile products, and conveyor belts. It is one of the most important synthetic fibers in the world. However, traditional polyester fibers have high crystallinity, close molecular arrangement, small intermolecular voids, poor hygroscopicity and elasticity, and the clothing made from them has poor comfort and is prone to bacterial growth after sweating. Therefore, modifying polyester fibers to meet the needs of various application scenarios has become the research focus in this field.

[0003] Patent CN102691128B discloses an elastic polyester fiber and a preparation method thereof. Based on PET as the basic raw material, a rigid group is introduced to synthesize a low-shrinkage polyester oligomer, and a flexible group is introduced to synthesize a high-shrinkage polyester oligomer. The two polyesters continue to copolymerize to form an elastic copolyester with the required molecular weight. After melting, it is processed by a spinning process to form an elastic polyester FDY fiber, which has irregular three-dimensional helical crimp characteristics. The fiber obtained by this invention has good elasticity, cheap raw materials, and low product cost. Patent CN115961467B discloses a porous antibacterial polyester fiber and a preparation method thereof. The preparation method includes the following steps: First, polyethylene terephthalate and a water-soluble polymer are blended to obtain a blended polyester. The blended polyester is sliced and granulated, and melt-spun to obtain a polyester fiber. Then, a photoinitiator and a coupling agent are added to an alcohol solvent to obtain a blended solution. Nano-modified bamboo charcoal and a surfactant are added to water to obtain an antibacterial agent dispersion liquid. Then, the obtained polyester fiber is successively immersed in the blended solution and the antibacterial agent dispersion liquid, and grafting reaction is carried out under ultraviolet light irradiation to obtain a modified polyester fiber. Finally, the modified polyester fiber is washed and dried to obtain a porous antibacterial polyester fiber. This invention couples the antibacterial agent to the polyester fiber through a coupling agent, so that the obtained porous polyester fiber has both hygroscopicity and antibacterial properties. At present, although there is research on the elasticity and antibacterial properties of polyester fibers, there are relatively few studies that can improve both the elasticity and antibacterial properties of polyester fibers at the same time.

[0004] Therefore, there is an urgent need in the market for an elastic polyester fiber with good antibacterial properties. Summary of the Invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a polyester fiber with good antibacterial properties and resilience.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] In the first aspect of the present invention, an antibacterial elastic polyester fiber is provided, which comprises the following raw materials in parts by weight: 95-105 parts of modified polyester, 5-9 parts of antibacterial agent, 0.5-1.5 parts of flame retardant, and 0.5-1 part of antioxidant.

[0008] In some embodiments, the preparation method of the modified polyester comprises the following steps:

[0009] (1) Add 2-hydroxyterephthalic acid, acrylic acid, and phosphoric acid into dichloromethane, react at 70-80 °C for 5-6 h, perform rotary evaporation, and dry to obtain a compound; add the obtained compound, allyl epoxy-terminated polyether, and sodium ethoxide into absolute ethanol, react at 55-65 °C for 30-60 min, wash, filter, and dry to obtain a polymer;

[0010] (2) Mix terephthalic acid, the polymer obtained in step (1), ethylene glycol, and pentanediol to make a slurry, react under a nitrogen atmosphere at 235-245 °C and 0.2-0.4 MPa. When the water output reaches 95-99 wt% of the theoretical value, end the reaction to obtain a reaction liquid;

[0011] (3) Add a catalyst and a heat stabilizer to the reaction liquid obtained in step (2), raise the temperature to 240-250 °C, evacuate the pressure to -0.1 KPa to 1 KPa within 45-55 min, raise the temperature to 275-285 °C, react for 1-2 h, and then continue to react under a pressure of 40-50 Pa for 4-5 h, discharge and dry to obtain the modified polyester.

[0012] Preferably, the mass ratio of 2-hydroxyterephthalic acid to acrylic acid is 1:(0.4-0.5).

[0013] Preferably, the mass ratio of terephthalic acid, ethylene glycol, and pentanediol is 1:(0.3-0.5):(0.4-0.6).

[0014] The present invention first grafts a double bond onto terephthalic acid, then reacts with allyl epoxy-terminated polyether to prepare a polymer, and then participates in an esterification reaction. The obtained modified polyester has good elasticity. The possible reason is that a freely movable side chain structure is added to the modified polyester, which reduces the crystallinity of the polyester and increases the elasticity of the polyester. In addition, the addition of the polyether structure reduces the glass transition temperature of the modified polyester, further increasing the elasticity of the modified polyester. At the same time, the epoxy group can crosslink with the amino group of the antibacterial agent, making the modified polyester have higher stability while increasing its elasticity, and having better compatibility with other additives, making the obtained polyester fiber have better uniformity and good mechanical properties. In addition, the polyether structure increases the skin-friendly property of the polyester fiber, making people feel more comfortable.

[0015] In some embodiments, the mass ratio of the compound described in step (1) to the allyl epoxy-terminated polyether is (1.5 - 1.8):1.

[0016] In some embodiments, the mass ratio of the terephthalic acid described in step (2) to the polymer is 1:(0.1 - 0.3).

[0017] By limiting the mass ratio of the compound to the allyl epoxy-terminated polyether, the present invention not only increases the elasticity of the modified polyester but also has a certain amount of epoxy groups crosslinked with the antibacterial agent, so that its mechanical properties will not decrease; in addition, by limiting the mass ratio of terephthalic acid to the polymer, the crystallinity of the modified polyester decreases, and the processability and elasticity increase.

[0018] In some embodiments, the preparation method of the antibacterial agent comprises the following steps:

[0019] 1) Stir an anhydrous ethanol solution of zinc acetate at 0.05 - 0.06 mol / L at 40 - 50 °C for 50 - 70 min, then add a sodium hydroxide solution at 0.08 - 0.09 mol / L while stirring, and at the same time add pentaerythritol diacrylate. After the addition is completed, stir at 40 - 50 °C for 1 - 2 h, let stand, filter, wash, and dry to obtain nano-zinc oxide;

[0020] 2) Add the nano-zinc oxide, zein, and azobisisobutyronitrile obtained in step 1) to anhydrous ethanol and stir at 70 - 80 °C for 1 - 2 h, filter, wash, and dry to obtain the antibacterial agent.

[0021] Preferably, the mass ratio of the anhydrous ethanol solution of zinc acetate, the sodium hydroxide solution, and pentaerythritol diacrylate in step 1) is (2.7 - 3.2):1.

[0022] The present invention prepares nano-zinc oxide by a hydrothermal synthesis method, and adds pentaerythritol diacrylate during the preparation process to graft multiple double bonds on the surface of zinc oxide, and then polymerizes with zein to obtain the antibacterial agent, which has good dispersibility and good antibacterial properties. The possible reason is that the double bonds on the surface of zinc oxide polymerize with zein to form a polymer film on the surface of zinc oxide, reducing the surface energy of nano-zinc oxide so that it can be evenly dispersed in the polyester, while increasing the antibacterial property of the polyester. In addition, the surface of the modified zinc oxide still has hydroxyl groups, and due to the steric hindrance of the cyclic structure of zein, the hydrogen bond interaction between its hydroxyl group and the hydroxyl group on pentaerythritol diacrylate is reduced, enabling it to be evenly dispersed. At the same time, zein can crosslink with the epoxy groups on the side chain of the modified polyester to increase the mechanical properties of the polyester fiber, so that the obtained polyester fiber has good hygroscopicity and washability.

[0023] In some embodiments, the mass ratio of the anhydrous ethanol solution of zinc acetate, the sodium hydroxide solution, and dipentaerythritol diacrylate in step 1) is (4.6 - 5.5):(1.6 - 1.8):1.

[0024] By limiting the mass ratio of the anhydrous ethanol solution of zinc acetate, the sodium hydroxide solution, and dipentaerythritol diacrylate, on the one hand, multiple double bonds are grafted onto the surface of zinc oxide to increase the crosslinking degree, thereby increasing the mechanical properties of polyester fibers. On the other hand, a certain amount of hydroxyl groups are added to the polyester fibers to increase the hygroscopicity.

[0025] In some embodiments, the mass ratio of the nano-zinc oxide to zein in step 2) is 1:(0.2 - 0.5).

[0026] By limiting the mass ratio of nano-zinc oxide to zein, the hydrogen bond interaction between hydroxyl groups can be reduced, the dispersion and hygroscopicity can be increased, and at the same time, the change in crosslinking degree can be avoided to prevent the elastic decline of polyester fibers.

[0027] In some embodiments, the flame retardant is dimethyl methylphosphonate or DOPO flame retardant.

[0028] In some embodiments, the antioxidant is any one of hindered phenol antioxidants, phosphite antioxidants, aromatic amine antioxidants, and hydroxylamine antioxidants.

[0029] The second aspect of the present invention provides a method for preparing antibacterial elastic polyester fibers, comprising the following steps:

[0030] S1. Add the modified polyester, antibacterial agent, flame retardant, and antioxidant into a twin-screw extruder for extrusion granulation. The feeding speed of the twin-screw extruder is 20 - 30 rpm, and the extrusion temperature is 240 - 250 °C to obtain masterbatch.

[0031] S2. Melt-spin the masterbatch obtained in step S1. Control the supply amount of the spinning metering pump to be 700 - 800 g / min, the spinning temperature to be 275 - 285 °C, the spinning speed to be 840 - 860 m / min. After the spinning is completed, place it at 30 - 40 °C for 0.5 - 1 h, and then raise the temperature to 60 - 70 °C for drawing processing. The drawing ratio is 1.5 - 2.5 times to obtain antibacterial elastic polyester fibers.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. By modifying polyester and zinc oxide and cooperating with other additives, the present invention obtains a polyester fiber with good antibacterial effect and resilience.

[0034] 2. By adding a freely movable side chain structure to the modified polyester, the crystallinity of the polyester is reduced, increasing its elasticity. In addition, the addition of a polyether structure lowers the glass transition temperature of the modified polyester, further increasing its elasticity. At the same time, the epoxy group can crosslink with the amino group of the antibacterial agent, making the modified polyester have higher stability while increasing its elasticity, and having better compatibility with other additives, resulting in better uniformity of the obtained polyester fiber and good mechanical properties. In addition, the polyether structure increases the skin-friendly property of the polyester fiber, making the skin feel more comfortable.

[0035] 3. The present invention prepares nano-zinc oxide by a hydrothermal synthesis method and adds pentaerythritol diacrylate during the preparation process to graft multiple double bonds on the surface of zinc oxide. The double bonds on the surface of zinc oxide polymerize with zein to form a polymer film on the surface of zinc oxide, reducing the surface energy of nano-zinc oxide so that it can be evenly dispersed in the polyester, while increasing the antibacterial property of the polyester. In addition, the surface of the modified zinc oxide still has hydroxyl groups, and due to the steric hindrance of the cyclic structure of zein, the hydrogen bond interaction between it and the hydroxyl groups on pentaerythritol diacrylate is reduced, enabling it to be evenly dispersed. At the same time, zein can crosslink with the epoxy group of the side chain of the modified polyester to increase the mechanical properties of the polyester fiber, making the obtained polyester fiber have good moisture absorption and wash resistance. Specific embodiments

[0036] The following will describe the present invention in combination with specific implementation examples. It should be noted that the examples and comparative examples below are only used to illustrate the present invention and not to limit it. Without departing from the main idea or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.

[0037] For the convenience of those skilled in the art to implement the present invention, the following is an explanation of some raw materials and manufacturers of the examples and comparative examples:

[0038] The compounds and related reagents used in the following examples and comparative examples can all be purchased from the market. Among them, allyl epoxy group-terminated polyether is purchased from Liaoning Kelong Fine Chemical Co., Ltd., model KL-91B.

[0039] Preparation Example 1

[0040] The preparation method of modified polyester-1 includes the following steps:

[0041] (1) Add 20 g of 2-hydroxyterephthalic acid, 9 g of acrylic acid, and 10 ml of 75 wt% phosphoric acid to 100 ml of dichloromethane, react at 75 °C for 5.5 h, rotary evaporate, and dry to obtain a compound; add 16 g of the obtained compound, 10 g of allyl epoxy-terminated polyether, and 1 g of sodium ethoxide to 200 ml of absolute ethanol, react at 60 °C for 45 min, wash, filter, and dry to obtain a polymer;

[0042] (2) Mix 10 g of terephthalic acid, 2 g of the polymer obtained in step (1), 4 g of ethylene glycol, and 5 g of pentanediol to make a slurry, react under a nitrogen atmosphere at 240 °C and 0.3 MPa. When the water output reaches 98 wt% of the theoretical value, end the reaction to obtain a reaction liquid;

[0043] (3) Add 0.1 g of antimony glycolate and 0.1 g of triphenyl phosphate to 10 g of the reaction liquid obtained in step (2), raise the temperature to 245 °C, evacuate the pressure to 0 KPa within 50 min, raise the temperature to 280 °C, react for 1.5 h, and then continue to react at a pressure of 45 Pa for 4.5 h, discharge and dry to obtain modified polyester-1.

[0044] Preparation Example 2

[0045] A preparation method of modified polyester-2, the specific steps are the same as those in Preparation Example 1, the difference is that the addition amount of the compound in step (1) is 13 g.

[0046] Preparation Example 3

[0047] A preparation method of modified polyester-3, the specific steps are the same as those in Preparation Example 1, the difference is that the addition amount of the polymer in step (2) is 0.7 g.

[0048] Preparation Example 4

[0049] A preparation method of polyester, comprising the following steps:

[0050] (1) Mix 10 g of terephthalic acid, 4 g of ethylene glycol, and 5 g of pentanediol to make a slurry, react under a nitrogen atmosphere at 240 °C and 0.3 MPa. When the water output reaches 98% of the theoretical value, end the reaction to obtain a reaction liquid;

[0051] (2) Add 0.1 g of antimony glycolate and 0.1 g of triphenyl phosphate to 10 g of the reaction liquid obtained in step (2), raise the temperature to 245 °C, evacuate the pressure to 0 KPa within 50 min, raise the temperature to 280 °C, react for 1.5 h, and then continue to react at a pressure of 45 Pa for 4.5 h, discharge and dry to obtain polyester.

[0052] Preparation Example 5

[0053] A preparation method of antibacterial agent-1, comprising the following steps:

[0054] 1) Stir the anhydrous ethanol solution of 5 g of 0.057 mol / L zinc acetate at 45 °C for 60 min, then add 1.7 g of 0.086 mol / L sodium hydroxide solution while stirring, and at the same time add 10 g of pentaerythritol diacrylate. After the addition is completed, stir at 45 °C for 1.5 h, let stand, filter, wash, and dry to obtain nano zinc oxide;

[0055] 2) Add 10 g of the nano zinc oxide obtained in step 1), 3 g of reverse zein, and 0.1 g of azobisisobutyronitrile to 20 ml of anhydrous ethanol, stir at 75 °C for 1.5 h, filter, wash, and dry to obtain antibacterial agent - 1.

[0056] Preparation Example 6

[0057] The preparation method of antibacterial agent - 2 is the same as that of Preparation Example 5, except that the addition amount of the anhydrous ethanol solution of zinc acetate in step 1) is 4.4 g.

[0058] Preparation Example 7

[0059] The preparation method of antibacterial agent - 3 is the same as that of Preparation Example 5, except that the addition amount of reverse zein in step 2) is 1 g.

[0060] Preparation Example 8

[0061] The preparation method of nano zinc oxide includes the following steps: Stir the anhydrous ethanol solution of 5 g of 0.057 mol / L zinc acetate at 45 °C for 60 min, then add 1.7 g of 0.086 mol / L sodium hydroxide solution while stirring, and at the same time add 10 g of pentaerythritol diacrylate. After the addition is completed, stir at 45 °C for 1.5 h, let stand, filter, wash, and dry to obtain nano zinc oxide.

[0062] Example 1

[0063] An antibacterial elastic polyester fiber, in parts by weight, comprises the following raw materials: 100 parts of modified polyester - 1, 7 parts of antibacterial agent - 1, 1 part of DOPO flame retardant, and 0.8 part of antioxidant 1010.

[0064] The preparation method of the antibacterial elastic polyester fiber in this example includes the following steps:

[0065] S1. Add modified polyester - 1, antibacterial agent - 1, DOPO flame retardant, and antioxidant 1010 to a twin - screw extruder for extrusion granulation. The feeding speed of the twin - screw extruder is 25 rpm, and the extrusion temperature is 245 °C to obtain masterbatch;

[0066] S2. Melt-spin the masterbatch obtained in step S1, control the supply rate of the spinning metering pump to be 750 g / min, the spinning temperature to be 280 °C, the spinning speed to be 850 m / min. After the spinning is completed, place it at 35 °C for 0.45 h, and then raise the temperature to 65 °C for drawing processing with a draw ratio of 2 times to obtain antibacterial elastic polyester fibers.

[0067] Example 2

[0068] An antibacterial elastic polyester fiber, by weight, contains the following raw materials: modified polyester - 195 parts, antibacterial agent - 15 parts, DOPO flame retardant 0.5 part, antioxidant 1010 0.5 part.

[0069] The preparation method of the antibacterial elastic polyester fiber in this example includes the following steps:

[0070] S1. Add modified polyester - 1, antibacterial agent - 1, DOPO flame retardant, and antioxidant 1010 to a twin-screw extruder for extrusion granulation. The feeding speed of the twin-screw extruder is 20 rpm, and the extrusion temperature is 240 °C to obtain a masterbatch;

[0071] S2. Melt-spin the masterbatch obtained in step S1, control the supply rate of the spinning metering pump to be 700 g / min, the spinning temperature to be 275 °C, the spinning speed to be 840 m / min. After the spinning is completed, place it at 30 °C for 1 h, and then raise the temperature to 60 °C for drawing processing with a draw ratio of 1.5 times to obtain antibacterial elastic polyester fibers.

[0072] Example 3

[0073] An antibacterial elastic polyester fiber, by weight, contains the following raw materials: modified polyester - 1105 parts, antibacterial agent - 19 parts, DOPO flame retardant 1.5 parts, antioxidant 1010 1 part.

[0074] The preparation method of the antibacterial elastic polyester fiber in this example includes the following steps:

[0075] S1. Add modified polyester - 1, antibacterial agent - 1, DOPO flame retardant, and antioxidant 1010 to a twin-screw extruder for extrusion granulation. The feeding speed of the twin-screw extruder is 30 rpm, and the extrusion temperature is 250 °C to obtain a masterbatch;

[0076] S2. Melt-spin the masterbatch obtained in step S1, control the supply rate of the spinning metering pump to be 800 g / min, the spinning temperature to be 285 °C, the spinning speed to be 860 m / min. After the spinning is completed, place it at 40 °C for 0.5 h, and then raise the temperature to 70 °C for drawing processing with a draw ratio of 2.5 times to obtain antibacterial elastic polyester fibers.

[0077] Example 4

[0078] An antibacterial elastic polyester fiber and its preparation method, the specific implementation manner is the same as that of Example 1, the difference is that the modified polyester-1 is replaced with the modified polyester-2 in equal amount.

[0079] Example 5

[0080] An antibacterial elastic polyester fiber and its preparation method, the specific implementation manner is the same as that of Example 1, the difference is that the modified polyester-1 is replaced with the modified polyester-3 in equal amount.

[0081] Example 6

[0082] An antibacterial elastic polyester fiber and its preparation method, the specific implementation manner is the same as that of Example 1, the difference is that the antibacterial agent-1 is replaced with the antibacterial agent-2 in equal amount.

[0083] Example 7

[0084] An antibacterial elastic polyester fiber and its preparation method, the specific implementation manner is the same as that of Example 1, the difference is that the antibacterial agent-1 is replaced with the antibacterial agent-3 in equal amount.

[0085] Example 8

[0086] An antibacterial elastic polyester fiber and its preparation method, the specific implementation manner is the same as that of Example 1, the difference is that the antibacterial agent-1 is replaced with nano-zinc oxide in equal amount.

[0087] Comparative Example 1

[0088] An antibacterial elastic polyester fiber and its preparation method, the specific implementation manner is the same as that of Example 1, the difference is that the modified polyester-1 is replaced with polyester in equal amount.

[0089] Performance Test

[0090] 1. Antibacterial Property

[0091] Cut the antibacterial elastic polyester fibers prepared in the above examples and comparative examples into fragments of 5mm×5mm, weigh 0.75±0.05g as the test sample, sterilize it under ultraviolet light for 15min, and conduct antibacterial property test on the test sample according to "GB / T 20994.3-2008 Evaluation of antibacterial properties of textiles - Part 3: Oscillation method", and record the antibacterial rate.

[0092] 2. Resilience

[0093] Use a universal testing machine to conduct resilience performance test on the antibacterial elastic polyester fibers prepared in the examples and comparative examples, apply a pre-tension of 0.2cN, the effective clamping distance is 20mm, the number of repeated stretching is 10 times, the descending speed of the clamp is 10mm / min, and the fixed elongation value is set to 10% of the effective clamping distance.

[0094] Resilience %=(L 1 -L1 ’) / (L 1 -L 0 )×100;

[0095] Wherein, L 0 is the original length of the specimen; L 1 is the length of the specimen after being stretched to a fixed elongation; L 1 ’ is the length of the specimen after resetting.

[0096] The test results are shown in Table 1

[0097] Table 1

[0098]

[0099] From the comparison of the experimental data of Examples 1 - 3 in Table 1, it can be seen that the polyester fiber obtained by the present invention has good antibacterial property and resilience; from the comparison between Example 4 and Example 1, it can be known that the change in the ratio of the compound to the allyl epoxy - terminated polyether may affect the cross - linking of the modified polyester and the modified zinc oxide, resulting in a decrease in the resilience of the polyester fiber; from the comparison between Example 5 and Example 1, it can be known that the change in the ratio of terephthalic acid, polymer, ethylene glycol and pentanediol may lead to a change in the crystallinity of the modified polyester and a decrease in the resilience of the polyester fiber; from the comparison between Example 6 and Example 1, it can be known that the change in the ratio of the absolute ethanol solution of zinc acetate, sodium hydroxide solution and pentaerythritol diacrylate may affect the grafting of pentaerythritol diacrylate, resulting in a decrease in both the antibacterial property and resilience of the polyester fiber; from the comparison between Example 7 and Example 1, it can be known that the change in the ratio of nano - zinc oxide to zein may lead to a change in the dispersibility of the antibacterial agent, resulting in a decrease in the resilience and antibacterial property of the polyester fiber; from the comparison between Example 8 and Example 1, it can be known that directly using nano - zinc oxide has poor dispersibility, resulting in a decrease in both the antibacterial property and resilience of the polyester fiber; from the comparison between Comparative Example 1 and Example 1, it can be known that using unmodified polyester results in a decrease in the resilience performance of the polyester fiber.

[0100] The above - mentioned are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, can make some changes or modifications to the above - disclosed technical content to form equivalent embodiments with equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An antibacterial elastic polyester fiber, characterized in that: The invention comprises the following raw materials in parts by weight: 95-105 parts of modified polyester, 5-9 parts of antibacterial agent, 0.5-1.5 parts of flame retardant and 0.5-1 parts of antioxidant.

2. The antibacterial elastic polyester fiber according to claim 1, characterized in that: The preparation method of the modified polyester comprises the following steps: (1) adding 2-hydroxyterephthalic acid, acrylic acid and phosphoric acid to dichloromethane, reacting at 70-80° C. for 5-6 hours, rotary evaporating and drying to obtain a compound; adding the obtained compound, allyl epoxy-terminated polyether and sodium ethoxide to anhydrous ethanol, reacting at 55-65° C. for 30-60 minutes, washing, filtering and drying to obtain a polymer; (2) mixing terephthalic acid, the polymer obtained in step (1), ethylene glycol and pentanediol and beating the mixture, reacting the mixture at 235-245° C. and 0.2-0.4 MPa under a nitrogen atmosphere, and terminating the reaction when the water output reaches 95-99 wt % of the theoretical value to obtain a reaction liquid; (3) Add a catalyst and a heat stabilizer to the reaction liquid obtained in step (2), raise the temperature to 240-250° C., reduce the pressure to -0.1 KPa to 1 KPa within 45-55 minutes, raise the temperature to 275-285° C., react for 1-2 hours, and then continue to react for 4-5 hours at a pressure of 40-50 Pa, discharge the material, and dry to obtain a modified polyester.

3. The antibacterial elastic polyester fiber according to claim 2, characterized in that: The mass ratio of the compound in step (1) to the allyl epoxy-terminated polyether is (1.5-1.8):

1.

4. The antibacterial elastic polyester fiber according to claim 2, characterized in that: The mass ratio of terephthalic acid to polymer in step (2) is 1:(0.1-0.3).

5. The antibacterial elastic polyester fiber according to claim 1, characterized in that: The preparation method of the antibacterial agent comprises the following steps: 1) Stirring a 0.05-0.06 mol / L zinc acetate anhydrous ethanol solution at 40-50° C. for 50-70 min, then adding a 0.08-0.09 mol / L sodium hydroxide solution while stirring, and adding pentaerythritol diacrylate at the same time. After the addition is completed, stirring at 40-50° C. for 1-2 h, standing, filtering, washing, and drying to obtain nano zinc oxide; 2) Add the nano zinc oxide, trans-zein and azobisisobutyronitrile obtained in step 1) into anhydrous ethanol and stir at 70-80° C. for 1-2 hours, filter, wash and dry to obtain an antibacterial agent.

6. The antibacterial elastic polyester fiber according to claim 5, characterized in that: The mass ratio of the anhydrous ethanol solution of zinc acetate to pentaerythritol diacrylate in step 1) is (4.6-5.5):

1.

7. The antibacterial elastic polyester fiber according to claim 5, characterized in that: The mass ratio of nano zinc oxide to trans-zein in step 2) is 1:(0.2-0.5).

8. The antibacterial elastic polyester fiber according to claim 1, characterized in that: The flame retardant is dimethyl methylphosphonate or DOPO flame retardant.

9. The antibacterial elastic polyester fiber according to claim 1, characterized in that: The antioxidant is any one of hindered phenol antioxidants, phosphite antioxidants, aromatic amine antioxidants, and hydroxylamine antioxidants.

10. A method for preparing the antibacterial elastic polyester fiber according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, adding modified polyester, antibacterial agent, flame retardant and antioxidant into a twin-screw extruder for extrusion granulation, the feeding speed of the twin-screw extruder is 20-30rpm, the extrusion temperature is 240-250°C, and masterbatch is obtained; S2. The masterbatch obtained in step S1 is melt-spun, the spinning metering pump supply is controlled to be 700-800 g / min, the spinning temperature is 275-285°C, the spinning speed is 840-860 m / min, and after spinning, it is placed at 30-40°C for 0.5-1h, and then heated to 60-70°C for stretching, and the stretching multiple is 1.5-2.5 times to obtain antibacterial elastic polyester fiber.

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