Antistatic polyester fiber prepared based on polyester regeneration and preparation of blended yarn thereof

Abstract

The application discloses antistatic polyester fiber prepared based on polyester regeneration and preparation of blended yarn thereof, and belongs to the technical field of polyester fiber processing, and is used for solving the technical problem that the antistatic property, moisture absorption and diffusion performance and mechanical strength of the blended yarn material composed of regenerated polyester fiber and cotton fiber in the prior art need to be further improved, and specifically comprises regenerated polyester fiber, a PDA modification layer and a hydrophilic polar coating layer wrapped outside the regenerated polyester fiber, the application is to recycle waste polyester to prepare sulfonate modified PET, and then melt spinning is performed on the sulfonate modified PET, polyethylene terephthalate and ethylene-vinyl acetate copolymer, a stable hydrophilic polar coating layer is formed by using polydopamine and chitosan deposition and glutaraldehyde crosslinking, and then the hydrophilic polar coating layer is blended with cotton fiber, so that the comprehensive optimization of the breaking strength, breaking elongation, surface resistivity, crease recovery angle and drop diffusion time and other performances of the blended yarn and fabric is realized.

Description

Technical Field

[0001] This invention relates to the field of polyester fiber processing technology, specifically to antistatic polyester fibers prepared based on recycled polyester and the preparation of blended yarns thereon. Background Technology

[0002] Polyester, or polyethylene terephthalate (PET) fiber, is widely used in clothing, home textiles, and industrial textiles due to its high strength, good dimensional stability, abrasion resistance, and ease of processing. At the same time, with the continuous increase in the amount of waste polyester products, the recycling of waste polyester materials not only helps to reduce resource consumption and environmental burden, but also improves the recycling level of polyester materials. Therefore, the development and application of recycled polyester fiber has become an important development direction in the textile materials field.

[0003] Currently, in the polyester recycling process, the sources of waste polyester are complex, usually containing oil, dyeing and finishing agent residues, colorants and other impurities. If not treated sufficiently, it can easily lead to insufficient purity of recycled polyester, poor melt processing stability, and further cause problems such as gelation, filament breakage, and uneven fiber structure during spinning, thereby affecting the mechanical properties and quality stability of the resulting fibers and yarns. Moreover, polyester itself is a hydrophobic polymer material with poor moisture absorption, and it is easy to accumulate static electricity during use, which can lead to problems such as dust attraction, clinging to the skin, fabric tangling, and discomfort when wearing it, especially in autumn and winter or in low humidity environments.

[0004] In textile applications, polyester fibers are often blended with cotton fibers to balance the moisture absorption and comfort of cotton fibers with the strength and dimensional stability of polyester fibers. However, in traditional recycled polyester blended yarns, the moisture absorption, antistatic properties, and mechanical strength of polyester fibers directly affect the overall performance of the blended yarn and fabric. If only fabric finishing is relied upon to improve antistatic and moisture absorption properties, it is often difficult to balance durability and processing stability.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide antistatic polyester fibers prepared based on recycled polyester and the preparation of blended yarns thereon, in order to solve the technical problem that the antistatic properties, moisture absorption and diffusion properties and mechanical strength of blended yarn materials composed of recycled polyester fibers and cotton fibers in the prior art need to be further improved.

[0007] The objective of this invention can be achieved through the following technical solution: antistatic polyester fiber prepared based on recycled polyester, comprising recycled polyester fiber and a PDA modification layer and a wettable polar coating layer covering the outside of the recycled polyester fiber;

[0008] The method for preparing the recycled polyester fiber is as follows: sulfonate-modified PET, ethylene-vinyl acetate copolymer, polyethylene terephthalate and additives are added to a twin-screw extruder, melt-mixed for 3-5 minutes, extruded into a melt spinning machine, and melt-spun to obtain recycled polyester fiber;

[0009] The hydrophilic polar coating layer is obtained by using glutaraldehyde as a crosslinking agent to promote the crosslinking and bonding of chitosan with PDA-coated recycled polyester fibers.

[0010] Furthermore, the weight ratio of the sulfonate-modified PET, ethylene-vinyl acetate copolymer, polyethylene terephthalate, and additives is (30-40):(5-7):(45-55):(1-2), and the additives consist of antioxidants, lubricants, dispersants, and plasticizers in a weight ratio of (3-4):(4-5):(1-2):(2-3). The antioxidant is antioxidant 1010, the lubricant is stearate, and the dispersant is ethylene bis-stearamide. The plasticizer is phthalate. The temperatures of the six temperature zones of the twin-screw extruder are 255℃, 260℃, 260℃, 260℃, 265℃ and 270℃ respectively. The spinning temperature of the melt spinning is 265-275℃, the spinning speed is 1200-1500m / min, the stretching temperature is 70-80℃, the pre-stretch ratio is 1.02-1.10, the first stretch ratio is 2.80-3.20, and the second stretch ratio is 1.05-1.15.

[0011] Furthermore, the sulfonate-modified PET is obtained by the following steps:

[0012] A1. Mix waste polyester with 10wt% sodium hydroxide solution at a solid-liquid ratio of 1:6-8, heat the reaction system to 70-80℃, ultrasonically disperse for 60-80 min, and then perform post-treatment to obtain pretreated polyester.

[0013] A2. Mix and stir the pretreated polyester, dissolving solution and activated carbon. Heat the reaction system to 170-180℃ and keep it at that temperature for 8-10 hours. Filter while hot. Add purified water to the filtrate and stir to disperse for 20-30 minutes. Then, perform post-treatment to obtain recycled PET.

[0014] A3. Under an inert gas atmosphere, recycled PET, sodium 5-sulfonate dimethyl isophthalate, ethylene glycol, and zinc acetate are mixed and stirred. The reaction system is heated to 140-150℃ and kept at this temperature for 2-3 hours. Polytetrahydrofuran ether glycol and a polycondensation catalyst are added to the reaction system, and the temperature is raised to 240-260℃. The reaction system is then evacuated to -0.1MPa and kept at this temperature and pressure for 4-5 hours. After post-treatment, sulfonate-modified PET is obtained.

[0015] Furthermore, in step A1, the solid-liquid ratio of waste polyester to 10wt% sodium hydroxide solution is 1:6-8. The post-treatment includes: after the reaction is complete, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, and then dried to obtain pretreated polyester.

[0016] Further, in step A2, the ratio of waste polyester, extract, activated carbon, and purified water is 4-5g:30mL:1g:50mL. The dissolving solution is composed of dimethyl sulfoxide and sodium dodecyl sulfate at a ratio of 50mL:1g. The post-treatment includes: after the reaction is complete, filtration is performed, the filter cake is washed with purified water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 60-70℃ and dried to constant weight to obtain recycled PET.

[0017] Further, in step A3, the weight ratio of the recycled PET, sodium 5-sulfonate dimethyl isophthalate, ethylene glycol, zinc acetate, polytetrahydrofuran ether glycol, and polycondensation catalyst is 100:(7-9):(30-40):(0.1-0.3):(20-30):(0.02-0.04), the polycondensation catalyst is antimony trioxide, and the post-treatment includes: after the reaction is completed, discharging the material while it is hot, cooling it, and slicing it to obtain sulfonate-modified PET.

[0018] Furthermore, the preparation method of PDA-coated recycled polyester fiber is as follows: dopamine hydrochloride and buffer solution are mixed and stirred until the system is dissolved. Recycled polyester fiber is added to the reaction system at room temperature, and the reaction is kept at the temperature for 20-24 hours. After post-treatment, PDA-coated recycled polyester fiber is obtained.

[0019] Furthermore, the ratio of dopamine hydrochloride, buffer solution, and raw polyester fiber is 1-2g:1L:5-6g, the buffer solution is 0.1mol / L Tris-HCl buffer solution with pH=8.5, and the post-treatment includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 70-80℃ and dried to constant weight to obtain PDA-coated recycled polyester fiber.

[0020] Furthermore, the preparation method of antistatic polyester fiber is as follows: chitosan and acetic acid solution are mixed and stirred until the system is dissolved. The reaction system is heated to 70-80℃. PDA-coated recycled polyester fiber is added to the reaction system and stirred for 60-90 min. Alkali solution is added to the reaction system to adjust the pH of the system to 8.5-9.5. Then glutaraldehyde is added to the reaction system and the reaction is carried out for 90-120 min. After post-treatment, a hydrophilic polar coating layer is formed on the outside of the PDA-coated recycled polyester fiber to obtain antistatic polyester fiber.

[0021] Furthermore, the ratio of chitosan, acetic acid solution, PDA-coated recycled polyester fiber, and glutaraldehyde is 2-3g:100mL:7-8g:1-1.5g, the concentration of the acetic acid solution is 1-2%vol, the alkaline solution is 2-3mol / L sodium hydroxide solution, and the post-treatment includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed three times with acetic acid solution, washed with purified water until neutral, the filter cake is transferred to a drying oven at 70-80℃, dried to constant weight, and a hydrophilic polar coating layer is formed on the outside of the PDA-coated recycled polyester fiber to obtain antistatic polyester fiber.

[0022] The present invention also proposes a blended yarn prepared from antistatic polyester fiber based on recycled polyester, wherein the blended yarn comprises 60-70 parts cotton fiber and 28-32 parts antistatic polyester fiber by weight.

[0023] The present invention has the following beneficial effects:

[0024] 1. This invention involves pre-treatment and dissolution purification of waste polyester fibers through sequential alkaline ultrasonic treatment, effectively removing oil stains, finishing agent residues, and other impurities from the waste polyester fibers. This reduces gel defects and stress concentration points during subsequent melt processing, providing a foundation for fiber forming quality and mechanical property stability. Furthermore, the introduction of sodium 5-sulfonate dimethyl isophthalate imparts strong polarity and hygroscopic capacity to the polyester chain segments, while polytetrahydrofuran ether diol imparts certain flexible chain characteristics to the system. Combined with the reinforcing effect of polyethylene terephthalate, the toughening effect of ethylene-vinyl acetate copolymer, and a multi-stage stretching and orientation process, the resulting fibers maintain high orientation and crystal support while also considering molecular chain flexibility and deformability. This results in a recycled system that not only has good spinnability but also facilitates the acquisition of high breaking strength and suitable elongation at break.

[0025] 2. This invention also introduces sulfonate groups into the polyester molecular chain of sulfonate-modified PET to improve the polarity and hygroscopic tendency of the fiber body, providing intrinsic conditions for charge dissipation. Furthermore, polydopamine is used to form a highly adhesive intermediate layer with catechol and amine groups on the fiber surface. These polar groups can improve the surface energy and hydrophilicity of the fiber, making it easier for the fiber to adsorb moisture from the environment. The surface charge can be dissipated more quickly through the conduction path formed by water molecules, improving antistatic properties. In addition, chitosan forms a hydrophilic polar coating layer rich in amino and hydroxyl groups on the fiber surface. After alkalization and glutaraldehyde crosslinking, the polydopamine coating layer and the chitosan coating layer are stably crosslinked, making it easier for the fiber surface to adsorb moisture from the air and form a continuous moisture conduction pathway. This allows the static charge on the fiber surface to be released more quickly, significantly reducing the surface resistivity of the fabric. At the same time, it improves the wetting and spreading ability of droplets on the fiber surface and the diffusion efficiency along the capillary channels between fibers.

[0026] 3. This invention also blends antistatic polyester fibers with cotton fibers. Cotton fibers themselves have good natural moisture absorption and softness, and can work with recycled polyester fibers that have been modified with sulfonate, coated with polydopamine, and cross-linked with chitosan to construct a fiber network that is more conducive to moisture migration and static dissipation. Meanwhile, the functionalized recycled polyester fibers rely on the polyester skeleton to provide good strength, dimensional stability, and elastic recovery. The polydopamine / chitosan surface of the antistatic polyester fibers improves the interfacial friction and cohesion between fibers, which helps to reduce fiber slippage under stress and improve yarn strength. The recovery characteristics of the polyester matrix, combined with the relatively stable structure of the fabric, are also conducive to the recovery of the fabric shape after pleating, thereby increasing the total crease recovery angle. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] In this invention, the effective component content of polyethylene terephthalate is 99%, and the melting point is 250-255℃;

[0029] In this invention, the ethylene-vinyl acetate copolymer is processed to injection molding grade, and the VA content in the copolymer is 12 wt%.

[0030] In this invention, the cotton fibers are selected from Xinjiang cotton, with a length of 33-39 mm and a fineness of 7000-8500 m / g.

[0031] Example 1

[0032] This embodiment provides a method for preparing antistatic polyester fibers based on recycled polyester, specifically including the following steps:

[0033] Step S1: Preparation of recycled PET

[0034] Waste polyester and 10wt% sodium hydroxide solution were added to a reaction flask at a solid-liquid ratio of 1:6 and mixed. The reaction flask was heated to 70℃ and ultrasonically dispersed for 60 min. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then dried to obtain pretreated polyester.

[0035] Dimethyl sulfoxide and sodium dodecyl sulfate were mixed evenly at a ratio of 50 mL: 1 g to obtain a solution;

[0036] Weigh out 40g of pretreated polyester, 300mL of dissolving solution and 10g of activated carbon and add them to the reaction flask. Stir and heat the reaction flask to 170℃ and keep it at that temperature for 8 hours. Filter while hot and transfer the filtrate to the reaction flask. Add 1000mL of purified water to the reaction flask and stir to disperse for 20 minutes. Filter and wash the filter cake with purified water until neutral. Dry the filter cake and transfer it to a drying oven at 60℃. Dry until constant weight to obtain recycled PET.

[0037] In the reaction, when waste polyester is heated in sodium hydroxide solution, the alkali can saponify some of the esters or oily residues, while ultrasound accelerates the desorption of surface impurities through cavitation, making the pretreated polyester surface cleaner. Subsequently, during high-temperature treatment in the dimethyl sulfoxide / sodium dodecyl sulfate system, dimethyl sulfoxide, as a highly polar solvent, can promote the swelling and dissolution of the pretreated polyester under high temperature conditions. Sodium dodecyl sulfate acts as a surface active and dispersant, which helps to improve the uniformity of the system. Activated carbon adsorbs color impurities, degradation by-products, and some small molecule organic impurities. Insoluble impurities are removed by filtration. The subsequent addition of a large amount of purified water to the filtrate reduces the solubility of the solvent dimethyl sulfoxide in PET, causing PET to precipitate and separating impurities from the polyester matrix. This reduces impurities, gel particles, and contamination residues, resulting in fewer defects in the melt during subsequent melt blending and spinning. The fibers are less likely to break prematurely due to stress concentration, improving breaking strength and reducing strength fluctuations.

[0038] Step S2: Preparation of sulfonate-modified PET

[0039] Weigh out 100g of recycled PET, 7g of sodium 5-sulfonate dimethyl isophthalate, 30g of ethylene glycol, and 0.1g of zinc acetate and add them to an argon-protected reaction flask. Stir the mixture and heat the flask to 140℃. Maintain the temperature for 2 hours. Add 20g of polytetrahydrofuran ether glycol and 0.02g of antimony trioxide as a polycondensation catalyst to the reaction flask. Heat the flask to 240℃ and evacuate it to -0.1MPa. Maintain the temperature and pressure for 4 hours. Discharge the mixture while it is still hot, cool it, and slice it to obtain sulfonate-modified PET.

[0040] In the reaction, recycled PET, sodium 5-sulfonate dimethyl isophthalate, ethylene glycol, and zinc acetate undergo transesterification at high temperature. The methyl ester group in sodium 5-sulfonate dimethyl isophthalate undergoes transesterification under the action of ethylene glycol and a catalyst, generating a terephthalate intermediate containing sodium sulfonate groups. This intermediate gradually exchanges with the hydroxyl groups or ester bonds at the ends of the PET molecular chain, allowing the sulfonate structure to enter the polyester backbone. The sodium sulfonate groups then become part of the polyester molecular structure through copolymerization. Subsequently, polytetrahydrofuran ether diol, which has hydroxyl groups at both ends, is added, allowing it to continue esterification / condensation with the ends of the polyester chain, thus inserting itself into the polyester molecular chain as a flexible segment. Antimony trioxide is used to catalyze the polyester polycondensation, while the vacuum facilitates the removal of low-molecular-weight byproducts, pushing the equilibrium towards higher molecular weights. The final product is a sulfonate-modified PET containing sulfonate ionic groups and a polyether flexible segment. Sulfonate groups are highly polar ionic groups. Their introduction can significantly increase the polarity and hygroscopic tendency of the polyester matrix, making it easier for the polyester to adsorb moisture from the environment. After absorbing moisture, the charge can migrate along the pathway formed by the polar sites and water molecules, thus reducing resistivity and enhancing antistatic properties. Moreover, the increased matrix polarity means that the fiber is no longer completely dependent on the surface coating for wetting, and droplets are more easily spread and adsorbed on the fiber surface, increasing the diffusion rate. The flexible segments of polytetrahydrofuran ether diol enhance the molecular chain mobility, making the fiber less brittle under external forces, thus increasing elongation. After the fabric is bent, these flexible segments also help the molecular chains readjust, improving the crease recovery of the material.

[0041] Step S3: Preparation of recycled polyester fibers

[0042] Antioxidant 1010, calcium stearate, ethylene bis-stearamide and diisobutyl phthalate were mixed in a weight ratio of 3:4:1:2 to obtain the additive.

[0043] Weigh out the following by weight: 30 parts of sulfonate-modified PET, 5 parts of ethylene-vinyl acetate copolymer, 45 parts of polyethylene terephthalate, and 1 part of additives. Add these to a twin-screw extruder. Set the temperatures of the six temperature zones of the twin-screw extruder to 255℃, 260℃, 260℃, 260℃, 265℃, and 270℃ respectively. Melt mix for 3 minutes and extrude into a melt spinning machine. Set the spinning temperature to 265℃, spinning speed to 1200m / min, stretching temperature to 70℃, pre-stretch ratio to 1.02, first stretch ratio to 2.80, and second stretch ratio to 1.05. Melt spin to obtain recycled polyester fibers with a fineness of 1.5-2.0D and a length of 35-70mm.

[0044] Step S4: Prepare PDA-coated recycled polyester fibers

[0045] Weigh out 10g of dopamine hydrochloride and 2L of 0.1mol / L Tris-HCl buffer solution (pH=8.5) and add them to the reaction flask. Stir until the system is dissolved. At room temperature, add 50g of recycled polyester fiber to the reaction flask and keep it at this temperature for 20h. Filter the mixture and wash the filter cake with purified water until it is neutral. Then dry the filter cake and transfer it to a drying oven at 70℃. Dry the filter cake to a constant weight to obtain PDA-coated recycled polyester fiber.

[0046] In a Tris-HCl buffer solution at pH 8.5, dopamine hydrochloride is desalted and progressively oxidized to dopaquinone, undergoing intramolecular cyclization, further oxidation, and covalent / non-covalent coupling, ultimately forming a polydopamine layer containing catechol, quinone, amine, and indole structural units. The polydopamine layer itself contains catechol hydroxyl and amino groups, which can increase the surface polarity and surface energy of the fiber, making the fiber more susceptible to moisture adsorption and improving the material's antistatic properties and water diffusion time. The quinone, catechol, and amino groups on the surface of the polydopamine layer can form hydrogen bonds, Schiff base reactions, Michael additions, or subsequent cross-linking synergistically with chitosan, thereby significantly improving the deposition fastness and uniformity of the chitosan layer.

[0047] Step S5: Prepare antistatic polyester fibers

[0048] Weigh 20g of chitosan and 1L of 1% vol acetic acid solution and add them to the reaction flask. Stir until the system is dissolved. Heat the reaction flask to 70℃ and add 70g of PDA-coated recycled polyester fiber. Keep the mixture warm and stir for 60min. Add 2mol / L sodium hydroxide solution to the reaction flask to adjust the pH of the system to 8.5. Then add 10g of glutaraldehyde to the reaction flask and keep the mixture warm for 90min. Cool the reaction flask to room temperature and filter. Wash the filter cake three times with 1% vol acetic acid solution and then wash it with purified water until neutral. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight. A hydrophilic polar coating layer is formed on the outside of the PDA-coated recycled polyester fiber to obtain antistatic polyester fiber.

[0049] Chitosan can be protonated and dissolved in acetic acid solution. After adding polydopamine-coated fibers to this system, chitosan first adheres to the fiber surface through hydrogen bonding, electrostatic interactions, and surface adsorption. Subsequently, the pH of the system is adjusted to 9 (alkaline) with NaOH, causing the amino groups on the chitosan molecules to deprotonate, reducing solubility, and gradually precipitating and depositing as a film on the fiber surface. Glutaraldehyde is then added, which reacts with the chitosan amino groups in a Schiff base reaction to form a cross-linked network. Simultaneously, because the polydopamine layer surface also contains amino and quinone structures, further covalent bonding or strong interactions occur between the chitosan layer and the polydopamine layer, thus making the surface coating more stable. The chitosan layer is rich in amino and hydroxyl groups, which have strong hydrophilicity. The fiber surface can more easily adsorb moisture from the air and form a continuous water film or ion-conducting layer. Once static charge is generated, it can be dissipated more quickly with the help of this hydrophilic layer, reducing the surface resistivity of the material. The chitosan layer also greatly improves surface wettability. After droplets fall onto the fabric surface, they can spread rapidly and diffuse through the capillary channels between fibers, shortening the diffusion time. The chitosan / polydopamine layer can also improve the friction and cohesion between fibers, reduce fiber slippage when the yarn is under stress, and thus benefit the yarn strength.

[0050] Example 2

[0051] This embodiment provides a method for preparing antistatic polyester fibers based on recycled polyester, specifically including the following steps:

[0052] Step S1: Preparation of recycled PET

[0053] Waste polyester and 10wt% sodium hydroxide solution were added to a reaction flask at a solid-liquid ratio of 1:7 and mixed. The reaction flask was heated to 75℃ and ultrasonically dispersed for 70 min. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then dried to obtain pretreated polyester.

[0054] Dimethyl sulfoxide and sodium dodecyl sulfate were mixed evenly at a ratio of 50 mL: 1 g to obtain a solution;

[0055] Weigh out 45g of pretreated polyester, 300mL of dissolving solution and 10g of activated carbon and add them to the reaction flask. Stir and heat the reaction flask to 175℃ and keep it at that temperature for 9h. Filter while hot and transfer the filtrate to the reaction flask. Add 1000mL of purified water to the reaction flask and stir to disperse for 25min. Filter and wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 65℃ and dry it to constant weight to obtain recycled PET.

[0056] Step S2: Preparation of sulfonate-modified PET

[0057] Weigh out 100g of recycled PET, 8g of sodium 5-sulfonate dimethyl isophthalate, 35g of ethylene glycol, and 0.2g of zinc acetate and add them to an argon-protected reaction flask. Stir the mixture and heat the flask to 145℃. Maintain the temperature for 2.5h. Add 25g of polytetrahydrofuran ether glycol and 0.03g of antimony trioxide as a polycondensation catalyst to the reaction flask. Heat the flask to 250℃ and evacuate it to -0.1MPa. Maintain the temperature and pressure for 4.5h. Discharge the mixture while it is still hot, cool it, and slice it to obtain sulfonate-modified PET.

[0058] Step S3: Preparation of recycled polyester fibers

[0059] Antioxidant 1010, sodium stearate, ethylene bis-stearamide and diamyl phthalate were mixed in a weight ratio of 3.5:4.5:1.5:2.5 to obtain the additive.

[0060] Weigh out the following components by weight: 35 parts of sulfonate-modified PET, 6 parts of ethylene-vinyl acetate copolymer, 50 parts of polyethylene terephthalate, and 1.5 parts of additives. Add these components to a twin-screw extruder. Set the temperatures of the six temperature zones of the twin-screw extruder to 255℃, 260℃, 260℃, 260℃, 265℃, and 270℃ respectively. Melt mix for 4 minutes and extrude into a melt spinning machine. Set the spinning temperature to 270℃, the spinning speed to 1350m / min, the stretching temperature to 75℃, the pre-stretch ratio to 1.06, the first stretch ratio to 3.00, and the second stretch ratio to 1.10. Melt spin to obtain recycled polyester fibers with a fineness of 1.5-2.0D and a length of 35-70mm.

[0061] Step S4: Prepare PDA-coated recycled polyester fibers

[0062] Weigh out 15g of dopamine hydrochloride and 2L of 0.1mol / L Tris-HCl buffer solution (pH=8.5) and add them to the reaction flask. Stir until the system is dissolved. At room temperature, add 55g of recycled polyester fiber to the reaction flask and keep it at this temperature for 22h. Filter the mixture and wash the filter cake with purified water until it is neutral. Then dry the filter cake and transfer it to a drying oven at 75℃. Dry the filter cake to a constant weight to obtain PDA-coated recycled polyester fiber.

[0063] Step S5: Prepare antistatic polyester fibers

[0064] Weigh 25g of chitosan and 1L of 1.5% vol acetic acid solution and add them to the reaction flask. Stir until the system is dissolved. Heat the reaction flask to 75℃. Add 75g of PDA-coated recycled polyester fiber to the reaction flask and stir for 75min. Add 2.5mol / L sodium hydroxide solution to the reaction flask to adjust the pH of the system to 9.0. Then add 13g of glutaraldehyde to the reaction flask and keep the reaction for 105min. Cool the reaction flask to room temperature and filter. Wash the filter cake three times with 1.5% vol acetic acid solution and then wash it with purified water until neutral. Transfer the filter cake to a drying oven at 75℃ and dry it to constant weight. A hydrophilic polar coating layer is formed on the outside of the PDA-coated recycled polyester fiber to obtain antistatic polyester fiber.

[0065] Example 3

[0066] This embodiment provides a method for preparing antistatic polyester fibers based on recycled polyester, specifically including the following steps:

[0067] Step S1: Preparation of recycled PET

[0068] Waste polyester and 10wt% sodium hydroxide solution were added to a reaction flask at a solid-liquid ratio of 1:8 and mixed. The reaction flask was heated to 80℃ and ultrasonically dispersed for 80 min. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then dried to obtain pretreated polyester.

[0069] Dimethyl sulfoxide and sodium dodecyl sulfate were mixed evenly at a ratio of 50 mL: 1 g to obtain a solution;

[0070] Weigh out 50g of pretreated polyester, 300mL of dissolving solution and 10g of activated carbon and add them to the reaction flask. Stir and heat the reaction flask to 180℃ and keep it at that temperature for 10h. Filter while hot and transfer the filtrate to the reaction flask. Add 1000mL of purified water to the reaction flask and stir to disperse for 30min. Filter and wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight to obtain recycled PET.

[0071] Step S2: Preparation of sulfonate-modified PET

[0072] Weigh out 100g of recycled PET, 9g of sodium 5-sulfonate dimethyl isophthalate, 40g of ethylene glycol, and 0.3g of zinc acetate and add them to an argon-protected reaction flask. Stir the mixture and heat the flask to 150℃. Maintain the temperature for 3 hours. Add 30g of polytetrahydrofuran ether glycol and 0.04g of antimony trioxide as a polycondensation catalyst to the reaction flask. Heat the flask to 260℃ and evacuate it to -0.1MPa. Maintain the temperature and pressure for 5 hours. Discharge the mixture while it is still hot, cool it, and slice it to obtain sulfonate-modified PET.

[0073] Step S3: Preparation of recycled polyester fibers

[0074] Antioxidant 1010, zinc stearate, ethylene bis-stearamide and dioctyl phthalate were mixed in a weight ratio of 4:5:2:3 to obtain the additive.

[0075] Weigh out the following by weight: 40 parts of sulfonate-modified PET, 7 parts of ethylene-vinyl acetate copolymer, 55 parts of polyethylene terephthalate, and 2 parts of additives. Add these to a twin-screw extruder. Set the temperatures of the six temperature zones of the twin-screw extruder to 255℃, 260℃, 260℃, 260℃, 265℃, and 270℃ respectively. Melt mix for 5 minutes, then extrude into a melt spinning machine. Set the spinning temperature to 275℃, spinning speed to 1500m / min, stretching temperature to 80℃, pre-stretch ratio to 1.10, first stretch ratio to 3.20, and second stretch ratio to 1.15. Melt spin to obtain recycled polyester fibers with a fineness of 1.5-2.0D and a length of 35-70mm.

[0076] Step S4: Prepare PDA-coated recycled polyester fibers

[0077] Weigh out 20g of dopamine hydrochloride and 2L of 0.1mol / L Tris-HCl buffer solution (pH=8.5) and add them to the reaction flask. Stir until the system is dissolved. At room temperature, add 60g of recycled polyester fiber to the reaction flask and keep it warm for 24h. Filter the mixture and wash the filter cake with purified water until neutral. Then dry the filter cake and transfer it to a drying oven at 80℃. Dry the filter cake to constant weight to obtain PDA-coated recycled polyester fiber.

[0078] Step S5: Prepare antistatic polyester fibers

[0079] Weigh 30g of chitosan and 1L of 2% vol acetic acid solution and add them to the reaction flask. Stir until the system is dissolved. Heat the reaction flask to 80℃ and add 80g of PDA-coated recycled polyester fiber. Keep the mixture warm and stir for 90min. Add 3mol / L sodium hydroxide solution to the reaction flask to adjust the pH of the system to 9.5. Then add 15g of glutaraldehyde to the reaction flask and keep the mixture warm for 120min. Cool the reaction flask to room temperature and filter. Wash the filter cake three times with 2% vol acetic acid solution and then wash it with purified water until neutral. Transfer the filter cake to a drying oven at 80℃ and dry it to constant weight. A hydrophilic polar coating layer is formed on the outside of the PDA-coated recycled polyester fiber to obtain antistatic polyester fiber.

[0080] Example 4

[0081] This embodiment provides a blended yarn prepared from antistatic polyester fiber based on recycled polyester, comprising, by weight: 60 parts cotton fiber and 28 parts antistatic polyester fiber prepared in Example 1. The blended yarn has a yarn count of 30S / 1, a linear density of 18tex, and a twist of 780 twists / s.

[0082] Example 5

[0083] This embodiment provides a blended yarn prepared from antistatic polyester fiber based on recycled polyester, comprising, by weight: 65 parts cotton fiber and 30 parts antistatic polyester fiber prepared in Example 2. The blended yarn has a yarn count of 32S / 1, a linear density of 19tex, and a twist of 840 twists / s.

[0084] Example 6

[0085] This embodiment provides a blended yarn prepared from antistatic polyester fiber based on recycled polyester, comprising, by weight: 70 parts cotton fiber and 32 parts antistatic polyester fiber prepared in Example 3. The blended yarn has a yarn count of 34S / 1, a linear density of 20tex, and a twist of 920 twists / s.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 6 is that, in the preparation of the antistatic polyester fiber, the pretreated polyester fiber in step S2 is used instead of the recycled PET in step S2.

[0088] Comparative Example 2

[0089] The difference between this comparative example and Example 6 is that, in the preparation of the antistatic polyester fiber, dimethyl isophthalate sodium 5-sulfonate was not added in step S2.

[0090] Comparative Example 3

[0091] The difference between this comparative example and Example 6 is that, in the preparation of the antistatic polyester fiber, step S5 is omitted, and the PDA-coated recycled polyester fiber prepared in step S4 is used as the antistatic polyester fiber.

[0092] Comparative Example 4

[0093] The difference between this comparative example and Example 6 is that, in the preparation of the antistatic polyester fiber, step S4 is omitted, and the recycled polyester fiber prepared in step S3 is used instead of the PDA-coated recycled polyester fiber in step S5.

[0094] Performance testing:

[0095] The breaking strength and elongation at break of the blended yarn samples prepared in Examples 4-6 and Comparative Examples 1-4 were determined in accordance with the standard GB / T 3916-2013 "Determination of breaking strength and elongation at break of single yarn in packaged textiles (CRE method)".

[0096] The blended yarn samples prepared in Examples 4-6 and Comparative Examples 1-4 were woven using a circular loom to prepare textile fabrics with a warp density of 110 ends / 10cm and a weft density of 85 ends / 10cm. The surface resistivity of the textile fabric samples was measured according to standard GB / T 12703.4-2010 "Evaluation of electrostatic properties of textiles - Part 4: Resistivity". The total crease recovery angle of the textile fabric samples was measured according to standard GB / T 3819-1997 "Determination of crease recovery of textile fabrics - Recovery angle method". The water droplet diffusion time of the textile fabric samples was measured according to standard GB / T 21655.1-2023 "Evaluation of moisture absorption and quick-drying properties of textiles - Part 1: Single-item combination test method". The relevant performance test data of the samples are shown in Table 1 below.

[0097] Table 1 - Performance Test Data of Samples

[0098]

[0099] Data Analysis:

[0100] The blended yarn samples prepared by this invention have a breaking strength of 35.1-36.2 cN / tex and a breaking elongation of 14.3-15.2%. The surface resistivity of the textile fabric samples prepared from the blended yarn reaches (0.97-1.03) × 10⁻⁶. 8 The total crease recovery angle reached 185.5-191.0°, and the water diffusion time reached 1.11-1.26s. All performance test data were superior to the comparative example, indicating that this invention improves the purity and processing stability of recycled PET by removing contaminants and impurities from waste polyester. Then, by introducing sodium 5-sulfonate dimethyl isophthalate and polytetrahydrofuran ether diol, the polyester molecular chain is bulk copolymerized and modified, giving the material high polarity, moisture absorption and antistatic potential, and a certain degree of flexibility. This is further enhanced by polyethylene terephthalate reinforcement and ethylene-vinyl acetate copolymerization. Regenerated polyester fibers were prepared by toughening and melt spinning with multi-stage stretching and orientation. Then, a highly adhesive active intermediate layer was constructed on the fiber surface using polydopamine. A stable hygroscopic polar coating layer was then formed through chitosan deposition and glutaraldehyde crosslinking, which improved the hygroscopic conductivity and droplet spreading and diffusion capacity of the fiber surface. Finally, the antistatic recycled polyester fiber was blended with cotton fiber to achieve synergistic effects between the fiber's intrinsic properties, surface functions, and textile structural properties, thereby comprehensively optimizing the blended yarn and fabric in terms of breaking strength, breaking elongation, surface resistivity, crease recovery angle, and droplet diffusion time.

[0101] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An antistatic polyester fiber prepared based on recycled polyester, characterized in that, Includes recycled polyester fibers and a PDA modification layer and a hydrophilic polar coating layer covering the outside of the recycled polyester fibers; The method for preparing the recycled polyester fiber is as follows: sulfonate-modified PET, ethylene-vinyl acetate copolymer, polyethylene terephthalate and additives are added to a twin-screw extruder, melt-mixed for 3-5 minutes, extruded into a melt spinning machine, and melt-spun to obtain recycled polyester fiber; The hydrophilic polar coating layer is obtained by using glutaraldehyde as a crosslinking agent to promote the crosslinking and bonding of chitosan with PDA-coated recycled polyester fibers.

2. The antistatic polyester fiber prepared based on recycled polyester according to claim 1, characterized in that, The weight ratio of the sulfonate-modified PET, ethylene-vinyl acetate copolymer, polyethylene terephthalate, and additives is (30-40):(5-7):(45-55):(1-2). The additives consist of antioxidants, lubricants, dispersants, and plasticizers in a weight ratio of (3-4):(4-5):(1-2):(2-3). The antioxidant is antioxidant 1010, the lubricant is stearate, the dispersant is ethylene bis-stearamide, and the plasticizer... The agent is phthalate. The temperatures of the six temperature zones of the twin-screw extruder are 255℃, 260℃, 260℃, 260℃, 265℃ and 270℃ respectively. The spinning temperature of the melt spinning is 265-275℃, the spinning speed is 1200-1500m / min, the stretching temperature is 70-80℃, the pre-stretch ratio is 1.02-1.10, the first stretch ratio is 2.80-3.20, and the second stretch ratio is 1.05-1.

15.

3. The antistatic polyester fiber prepared based on recycled polyester according to claim 1, characterized in that, The sulfonate-modified PET is obtained by the following steps: A1. Mix waste polyester with 10wt% sodium hydroxide solution at a solid-liquid ratio of 1:6-8, heat the reaction system to 70-80℃, ultrasonically disperse for 60-80 min, and then perform post-treatment to obtain pretreated polyester. A2. Mix and stir the pretreated polyester, dissolving solution and activated carbon. Heat the reaction system to 170-180℃ and keep it at that temperature for 8-10 hours. Filter while hot. Add purified water to the filtrate and stir to disperse for 20-30 minutes. Then, perform post-treatment to obtain recycled PET. A3. Under an inert gas atmosphere, recycled PET, sodium 5-sulfonate dimethyl isophthalate, ethylene glycol, and zinc acetate are mixed and stirred. The reaction system is heated to 140-150℃ and kept at this temperature for 2-3 hours. Polytetrahydrofuran ether glycol and a polycondensation catalyst are added to the reaction system, and the temperature is raised to 240-260℃. The reaction system is then evacuated to -0.1MPa and kept at this temperature and pressure for 4-5 hours. After post-treatment, sulfonate-modified PET is obtained.

4. The antistatic polyester fiber prepared based on recycled polyester according to claim 3, characterized in that, In step A1, the solid-liquid ratio of waste polyester to 10wt% sodium hydroxide solution is 1:6-8. The post-treatment includes: after the reaction is complete, cooling the reaction system to room temperature, filtering, washing the filter cake with purified water until neutral, and then drying to obtain pretreated polyester. In step A2, the ratio of waste polyester, extract, activated carbon, and purified water is 4-5g:30mL:1g:50mL. The dissolving solution consists of dimethyl sulfoxide and sodium dodecyl sulfate at a ratio of 50mL:1g. The post-treatment includes: after the reaction is complete, filtering, washing the filter cake with purified water until neutral, and then drying to obtain pretreated polyester. The filter cake is dried and transferred to a drying oven at 60-70℃ and dried to constant weight to obtain recycled PET. In step A3, the weight ratio of the recycled PET, sodium isophthalate 5-sulfonate, ethylene glycol, zinc acetate, polytetrahydrofuran ether glycol and polycondensation catalyst is 100:(7-9):(30-40):(0.1-0.3):(20-30):(0.02-0.04), and the polycondensation catalyst is antimony trioxide. The post-treatment includes: after the reaction is completed, the material is discharged while hot, cooled and sliced ​​to obtain sulfonate modified PET.

5. The antistatic polyester fiber prepared based on recycled polyester according to claim 1, characterized in that, The preparation method of PDA-coated recycled polyester fiber is as follows: Dopamine hydrochloride and buffer solution are mixed and stirred until the system is dissolved. Recycled polyester fiber is added to the reaction system at room temperature and the reaction is kept at the temperature for 20-24 hours. After post-treatment, PDA-coated recycled polyester fiber is obtained.

6. The antistatic polyester fiber prepared based on recycled polyester according to claim 5, characterized in that, The ratio of dopamine hydrochloride, buffer solution, and raw polyester fiber is 1-2g:1L:5-6g. The buffer solution is a 0.1mol / L Tris-HCl buffer solution with pH=8.

5. The post-treatment includes: after the reaction is complete, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, dried, and the filter cake is transferred to a drying oven at 70-80℃ and dried to constant weight to obtain PDA-coated recycled polyester fiber.

7. The antistatic polyester fiber prepared based on recycled polyester according to claim 1, characterized in that, The preparation method of antistatic polyester fiber is as follows: chitosan and acetic acid solution are mixed and stirred until the system is dissolved. The reaction system is heated to 70-80℃. PDA-coated recycled polyester fiber is added to the reaction system and stirred for 60-90 min. Alkali solution is added to the reaction system to adjust the pH of the system to 8.5-9.

5. Then glutaraldehyde is added to the reaction system and the reaction is carried out for 90-120 min. After post-treatment, a hydrophilic polar coating layer is formed on the outside of the PDA-coated recycled polyester fiber to obtain antistatic polyester fiber.

8. The antistatic polyester fiber prepared based on recycled polyester according to claim 7, characterized in that, The ratio of chitosan, acetic acid solution, PDA-coated recycled polyester fiber, and glutaraldehyde is 2-3g:100mL:7-8g:1-1.5g. The concentration of the acetic acid solution is 1-2%vol, and the alkaline solution is 2-3mol / L sodium hydroxide solution. The post-treatment includes: after the reaction is complete, the reaction system is cooled to room temperature, filtered, the filter cake is washed three times with acetic acid solution, washed with purified water until neutral, the filter cake is transferred to a drying oven at 70-80℃ and dried to constant weight, forming a hydrophilic polar coating layer on the outside of the PDA-coated recycled polyester fiber, thus obtaining antistatic polyester fiber.

9. The blended yarn prepared from antistatic polyester fiber based on recycled polyester according to any one of claims 1-8, characterized in that, By weight, the blended yarn comprises 60-70 parts cotton fiber and 28-32 parts antistatic polyester fiber.

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