Functional regenerated polyester-nylon composite superfine fiber and preparation method thereof

Abstract

The invention discloses a functional regenerated polyester-nylon composite superfine fiber and a preparation method thereof, and belongs to the technical field of composite fibers. The fiber is of a core-skin structure, a core layer is made of modified regenerated polyester containing superfine graphite, polyethylene glycol and an antibacterial additive, and a skin layer is made of modified regenerated chinlon containing a chain extender, a silane coupling agent and an antibacterial additive; the preparation method comprises the steps of regenerated raw material ultrasonic cleaning, melting chain extension, modified melt preparation, composite spinning and post-treatment splitting. The single fiber linear density of the fiber is 0.142-0.150 dtex, the breaking strength is larger than or equal to 6.5 cN / dtex, the thermal decomposition temperature is larger than or equal to 345 DEG C, the antibacterial rate is larger than or equal to 99.2%, the specific surface area is larger than or equal to 15200 cm < 2 > / g, and the fiber is excellent in comprehensive performance and can be used in the field of high-end electronic dust-free cloth. And the utilization rate of regenerated raw materials is not less than 90%.

Description

Technical Field

[0001] This invention relates to the field of composite fiber production technology, specifically to a functional recycled polyester-nylon composite microfiber and its preparation method. Background Technology

[0002] Polyester-nylon composite microfiber combines the high strength and good shape retention of polyester with the abrasion resistance and moisture absorption of nylon, making it widely used in textiles, electronic cleaning, and other fields. With increasing environmental awareness, recycled polyester-nylon composite fibers have become a research hotspot. Existing technologies have explored related approaches: using recycled polyester chips as the core / lobes and nylon as the corresponding structure, adding activated carbon, softeners, and antibacterial powder to achieve raw material regeneration and basic antibacterial properties. However, this technology does not address fiber thermal stability, and the recycled raw materials only undergo simple washing, leaving impurities that affect fiber uniformity, resulting in limited improvement in mechanical properties after fiber opening. A two-step method uses recycled chips obtained from polyester / nylon waste yarn through melt chain extension, followed by composite spinning, which improves the mechanical properties of the recycled fiber. However, the chain extender is a conventional bisoxazoline type, which does not address the viscosity differences between the polyester and nylon components and does not incorporate thermal stability and antibacterial design, making it difficult to meet the comprehensive performance requirements of high-end electronics applications. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a functional recycled polyester-nylon composite microfiber and its preparation method, specifically achieved through the following technical solution: A functional recycled polyester-nylon composite microfiber, comprising modified recycled polyester as the core layer and modified recycled nylon as the sheath layer; by weight, the modified recycled polyester accounts for 75-85 parts and the modified recycled nylon accounts for 15-25 parts. The modified recycled polyester comprises, by weight, 90-95 parts recycled polyester chips, 2.5-3.5 parts ultrafine graphite powder, 2-3 parts polyethylene glycol, and 0.4-0.6 parts antibacterial additives; The recycled polyester chips are made from waste PET fabric and waste polyester filaments through sorting, ultrasonic cleaning, crushing, melting and chain extension, filtering and pelletizing. The mass ratio of waste PET fabric to waste polyester filaments is 4-5:3-4. The recycled nylon chips are made from waste PA6 fabric and waste nylon yarn through sorting, ultrasonic cleaning, crushing, melting and chain extension, filtration and pelletizing. The mass ratio of waste PA6 fabric to waste nylon yarn is 7-8:4-5.

[0004] The antibacterial adjuvant is made by mixing silver-loaded zirconium phosphate and nano zinc oxide in a mass ratio of 4:1.

[0005] The modified recycled nylon comprises, by weight: 92-96 parts recycled nylon chips, 3-3.5 parts silane coupling agent, 2.5-3 parts titanium fluoride, and 0.3-0.5 parts the antibacterial additive.

[0006] The ultrafine graphite powder has a particle size of 500-800 nm and is ultrasonically dispersed by a 0.5 wt% sodium carboxymethyl cellulose aqueous solution.

[0007] A method for preparing functional recycled polyester-nylon composite microfiber, characterized by comprising the following steps: Step 1, Pretreatment of recycled polyester raw materials: Weigh waste PET fabric and waste polyester filaments according to the formula, remove impurities and put them into an ultrasonic cleaning tank, add 0.3wt% sodium dodecylbenzenesulfonate aqueous solution for ultrasonic cleaning; after cleaning, dehydrate, dry and cut to obtain a mixture of waste polyester filaments. Step 2, preparation of recycled polyester chips: The polyester waste filament mixture obtained in Step 1 is added to the feed hopper of a single screw extruder, and at the same time, bisoxazoline chain extender A is added at an amount of 0.5-0.55 wt% of the polyester waste filament mixture; after the melt is extruded from the screw extruder, it enters a vertical melt two-stage pre-filter, and then is extruded through a casting head. After solidification, it is sliced ​​to obtain recycled polyester chips. Step 3, Preparation of modified recycled polyester melt; Take 90-95 parts of the recycled polyester chips obtained in Step 2, add 2.5-3.5 parts of ultrafine graphite powder, 2-3 parts of polyethylene glycol, and 0.4-0.6 parts of antibacterial additive, mix and feed into a twin-screw extruder, filter the molten material through a metal mesh melt filter to obtain modified recycled polyester melt; Step 4, pretreatment of recycled nylon raw materials; weigh PA6 fabric and nylon waste yarn according to the formula, remove impurities and put them into an ultrasonic cleaning tank, add 0.2wt% sodium alginate aqueous solution for ultrasonic cleaning; after cleaning, dehydrate, dry and slice to obtain nylon waste yarn mixture; Step 5, preparation of recycled nylon chips: The nylon waste filament mixture obtained in step 4 is added to the feed hopper of a single screw extruder. At the same time, bisoxazoline chain extender B is added at an addition amount of 0.55-0.6 wt% of the nylon waste filament mixture. After the melt is extruded from the screw extruder, it enters a vertical melt two-stage pre-filter, is extruded through the casting head, solidified, and sliced ​​to obtain recycled nylon chips. Step 6, Preparation of modified recycled nylon melt; Take 92-96 parts of the recycled nylon chips obtained in Step 5, add 3-3.5 parts of silane coupling agent, 2.5-3 parts of titanium fluoride, and 0.3-0.5 parts of antibacterial agent, mix and feed into a twin-screw extruder, filter the molten material through a metal mesh melt filter to obtain modified recycled nylon melt; Step 7, Composite spinning; The modified recycled polyester melt obtained in step 3 and the modified recycled nylon melt obtained in step 6 are respectively fed into two independent spinning boxes of the composite spinning machine; The melt enters the conjugate spinning assembly, and the nascent yarn is bundled, oiled and wound to obtain POY yarn cake after cooling. Step 8, post-treatment and fiber opening: After balancing and texturing, the POY yarn cake is successively alkali washed, water washed, acid washed and water washed, and then dried to obtain functional recycled polyester-nylon composite microfiber.

[0008] The preparation method of bisoxazoline chain extender A in step 2 is as follows: Under a nitrogen atmosphere, 2-isopropenyl-2-oxazoline and mercapto-polyethylene glycol-mercapto with a molecular weight of 200 are added to a reaction vessel at a molar ratio of 2.1:1. Then, 3 to 5 times the total mass of the reactants of solvent DMF and 0.5% of the total mass of the reactants of photoinitiator 500 are added. The reaction is carried out under ultraviolet light at a wavelength of 365 nm for 12 hours. After the reaction is completed, the mixture is introduced into a rotary evaporator and the solvent is removed at a temperature of 80°C and a vacuum degree of -0.09 MPa. Then, the mixture is dried at a temperature of 80°C and a vacuum degree of -0.09 MPa for 6 hours to obtain bisoxazoline chain extender A.

[0009] The preparation method of bisoxazoline chain extender B in step 5 is as follows: Under a nitrogen atmosphere, 2-isopropenyl-2-oxazoline and mercapto-polyethylene glycol-mercapto with a molecular weight of 400 are added to a reaction vessel at a molar ratio of 2.1:1. Then, 3 to 5 times the total mass of the reactants of DMF solvent and 0.5% of the total mass of the reactants of photoinitiator 500 are added. The reaction is carried out under ultraviolet light with a wavelength of 365 nm for 12 h. After the reaction is completed, the solvent is removed by rotary evaporator at 80 °C and -0.09 MPa, and then vacuum dried at 80 °C and -0.09 MPa for 6 h to obtain bisoxazoline chain extender B.

[0010] In step 3, the temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 270–275℃, Zone 2: 278–282℃, Zone 3: 285–288℃, Zone 4: 288–290℃, and the screw speed is 180–200 r / min. In step 6, the temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 260–265℃, Zone 2: 268–272℃, Zone 3: 275–278℃, Zone 4: 278–280℃, and the screw speed is 180 r / min.

[0011] In step 5, the temperatures of each zone of the single-screw extruder are as follows: feeding section 258-260℃, compression section 265-268℃, metering section 272-275℃, and screw speed 140 r / min.

[0012] In step 7, the spinning box temperature is 288-290℃ for the polyester side and 278-280℃ for the nylon side.

[0013] The technical solution of this invention has the following advantages: This invention provides a functional recycled polyester-nylon composite microfiber and its preparation method. By constructing a core-skin composite structure with modified recycled polyester as the core layer and modified recycled nylon as the sheath layer, it addresses the shortcomings of existing recycled polyester-nylon composite fibers, such as insufficient thermal stability, poor fiber uniformity due to incomplete cleaning of recycled raw materials, limited improvement in mechanical properties after fiber opening, and the inability of conventional chain extenders to adapt to the viscosity differences between the two components of polyester and nylon, as well as the failure to balance thermal stability and high-efficiency antibacterial properties, which makes it difficult to meet the needs of high-end electronics. The invention systematically optimizes the entire process from raw material selection, component modification, to preparation, ultimately achieving a synergistic improvement in the overall performance and environmental friendliness of the fiber, effectively solving the pain points of existing technologies.

[0014] In the raw material pretreatment stage, this invention uses a 0.3wt% sodium dodecylbenzenesulfonate aqueous solution for ultrasonic cleaning of recycled polyester raw materials and a 0.2wt% sodium alginate aqueous solution for ultrasonic cleaning of recycled nylon raw materials. Before cleaning, damaged, unevenly dyed, and blended raw materials are sorted and removed. This design can more efficiently remove oil, impurities, and residual dyes adhering to the surface of the raw materials, while ensuring the purity of the recycled raw materials and avoiding interference from residual impurities on subsequent melt spinning. It significantly improves the uniformity of the fiber after forming and lays the foundation for the stability of mechanical properties after fiber opening. This solves the problem of poor fiber uniformity and limited mechanical properties caused by incomplete cleaning of raw materials in the prior art.

[0015] In the stage of preparing recycled chips, this invention uses bisoxazoline chain extenders: for recycled polyester chips, bisoxazoline chain extender A is prepared by mixing 2-isopropenyl-2-oxazoline with 200 thiol-polyethylene glycol-thiol in a molar ratio of 2.1:1; for recycled nylon chips, bisoxazoline chain extender B is prepared by mixing 2-isopropenyl-2-oxazoline with 400 thiol-polyethylene glycol-thiol in a molar ratio of 2.1:1. By controlling the molecular weight of the polyethylene glycol segments in the chain extender, the viscosity of the modified recycled polyester melt and the modified recycled nylon melt is precisely matched, effectively reducing the breakage rate of composite spinning. Simultaneously, the chain extender effect achieves an intrinsic viscosity of 0.78–0.81 dL / g for recycled polyester chips and 0.88–0.91 dL / g for recycled nylon chips, providing structural support for the excellent mechanical properties of fiber breaking strength ≥6.5 cN / dtex. This solves the problems of poor compatibility of chain extenders and insufficient improvement in mechanical properties in existing technologies. Furthermore, a multi-stage filtration system, including vertical melt double-stage pre-filtration and modified melt metal mesh filtration, is introduced during the melting process, ensuring that the fiber impurity content is ≤0.001 wt%, further guaranteeing fiber purity and performance stability.

[0016] In terms of component modification, the ultrafine graphite powder added to the core-layer modified recycled polyester significantly improves the fiber's thermal stability due to the layered structure of graphite, achieving a thermal decomposition temperature ≥345℃, thus overcoming the deficiency of insufficient fiber thermal stability in existing technologies. Simultaneously, this ultrafine graphite powder synergistically improves the melt flowability of the core layer with polyethylene glycol, enhancing the interfacial bonding with the skin layer. Furthermore, the antibacterial additives in both the core and skin layers, through the synergistic effect of the long-lasting antibacterial properties of silver-loaded zirconium phosphate and the broad-spectrum antibacterial properties of nano-zinc oxide, achieve an antibacterial rate of ≥99.2% against Escherichia coli, providing a more durable and broad-spectrum antibacterial effect that meets the sterile environment requirements of high-end electronics applications. In addition, the silane coupling agent in the skin layer enhances the interfacial compatibility between the skin and core layers, preventing interlayer delamination; while titanium fluoride improves the mechanical strength and surface activity of the skin layer, synergistically contributing to a fiber specific surface area ≥15200 cm². 2 / g, enhancing adsorption capacity in the field of electronic cleaning and further adapting to high-end application scenarios.

[0017] In the post-processing, through multiple steps of balancing, texturing, alkali washing, water washing, acid washing, and water washing, efficient fiber opening and performance regulation are achieved, so that the linear density of a single fiber is precisely controlled at 0.142 to 0.150 dtex and the boiling water shrinkage rate is stable at 12.5 to 14.0%, ensuring fiber dimensional stability and meeting the stringent requirements of high-end textile and electronics fields.

[0018] Meanwhile, this invention achieves a utilization rate of ≥90% for recycled raw materials such as waste PET fabric, waste polyester filament, waste PA6 fabric, and waste nylon filament. It improves the overall performance of the fibers while achieving environmental sustainability, aligning with the trend of green manufacturing and possessing significant technical, economic, and environmental benefits. In summary, the functional recycled polyester-nylon composite microfiber of this invention exhibits synergistic advantages in mechanical strength, thermal stability, antibacterial properties, surface adsorption characteristics, and environmental friendliness. It can be stably applied in high-end electronic cleanroom cloths and other fields with stringent requirements for fiber performance, solving the core problem of existing technologies' difficulty in balancing performance and environmental protection. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] The overall technical solution of this invention is as follows: This invention provides a functional recycled polyester-nylon composite microfiber, which has a core-skin structure; specifically, it has modified recycled polyester as the core layer and modified recycled nylon as the skin layer; by mass, the modified recycled polyester in the core layer accounts for 75-85 parts and the modified recycled nylon in the skin layer accounts for 15-25 parts.

[0022] Modified recycled polyester comprises, by weight: 90-95 parts recycled polyester chips, 2.5-3.5 parts ultrafine graphite powder, 2-3 parts polyethylene glycol (PEG-2000), and 0.4-0.6 parts antibacterial additives.

[0023] Among them, recycled polyester chips are made from waste PET fabric and waste polyester filaments, which are sorted, ultrasonically cleaned, crushed, melted and extended, filtered and granulated. The intrinsic viscosity is 0.78 to 0.81 dL / g.

[0024] The ultrafine graphite powder has a particle size of 500-800 nm and is ultrasonically dispersed in a 0.5 wt% sodium carboxymethyl cellulose (CMC) aqueous solution.

[0025] The antibacterial adjuvant is made by mixing silver-loaded zirconium phosphate and nano zinc oxide in a mass ratio of 4:1; wherein the particle size of the silver-loaded zirconium phosphate is 200-300 nm and the particle size of the nano zinc oxide is 50-80 nm.

[0026] The modified recycled nylon comprises, by weight: 92-96 parts recycled nylon chips, 3-3.5 parts silane coupling agent (KH-550), 2.5-3 parts titanium fluoride with a particle size of 100-150 nm, and 0.3-0.5 parts of the aforementioned antibacterial additives.

[0027] Among them, recycled nylon chips are made from waste PA6 fabric and waste nylon yarn, which are sorted, ultrasonically cleaned, crushed, melted and extended, filtered and granulated. The intrinsic viscosity is 0.88 to 0.91 dL / g.

[0028] The composite microfiber has a single fiber linear density of 0.142–0.150 dtex, a breaking strength of ≥6.5 cN / dtex, a boiling water shrinkage rate of 12.5–14.0%, a thermal decomposition temperature of ≥345℃, an antibacterial rate against Escherichia coli of ≥99.2%, and a specific surface area of ​​≥15200 cm² / g.

[0029] The aforementioned functional recycled polyester-nylon composite microfiber was prepared by the following method.

[0030] Step 1, pretreatment of recycled polyester raw materials: Select 40-50 kg of waste PET fabric and 30-40 kg of 222dtex / 96f polyester waste yarn that do not contain natural fiber impurities such as spandex and wool, and sort them to remove damaged, unevenly dyed and blended parts.

[0031] Place the sorted raw materials into an ultrasonic cleaning tank, add 180-200L of 0.3wt% sodium dodecylbenzenesulfonate aqueous solution, set the ultrasonic power to 280-300W, the temperature to 55-58℃, and ultrasonically clean for 45-50 minutes.

[0032] After cleaning, transfer the raw materials into a dewatering machine, set the speed to 750-800 r / min, and dewater for 18-20 minutes.

[0033] After dehydration, the product is placed in an oven with a temperature of 105–110℃, a wind speed of 1.8–2.0 m / s, and dried for 2.5–3 hours.

[0034] After drying, the material is transferred to a fiber shredder and shredded to a particle size of 0.5-1.2 mm to obtain a mixture of polyester waste fibers.

[0035] Step 2, preparation of recycled polyester chips: The polyester waste filament mixture obtained in Step 1 is added to the feed hopper of a single screw extruder, and at the same time, bisoxazoline chain extender A is added at an amount of 0.5-0.55 wt% of the polyester waste filament mixture.

[0036] The temperatures of each zone of the single-screw extruder are set as follows: feeding section 262–265℃, compression section 275–278℃, metering section 282–285℃, and screw speed 140–150 r / min. After the melt is extruded from the screw extruder, it enters a vertical melt two-stage pre-filter. The first stage filter element is a 100-mesh pleated multi-layer metal mesh, and the second stage is a 200-mesh pleated multi-layer metal mesh. The filtration pressure is controlled at 11–12 MPa. The filtered recycled polyester melt is extruded through a 2 mm diameter cast strip head and cooled in a 23–25℃ water bath for 2.5–3 minutes until solidified. Then it is sent to a slicing machine to obtain recycled polyester chips.

[0037] The filter element of the vertical melt dual-stage pre-filter is a pleated multi-layer metal mesh made of 316L stainless steel with a porosity of ≥85%.

[0038] According to GB / T14190-2008 standard, the intrinsic viscosity of recycled polyester chips was determined by Ubbelohde viscometer at 25℃ using a solvent composed of phenol and tetrachloroethane in a mass ratio of 1:1, ensuring that it was 0.78~0.81dL / g.

[0039] The preparation method of the aforementioned bisoxazoline chain extender A is as follows: Under a nitrogen atmosphere, 2-isopropenyl-2-oxazoline and mercapto-polyethylene glycol-mercapto-mercapto-200 are added to a reaction vessel at a molar ratio of 2.1:1. Then, 3 to 5 times the total mass of the reactants of solvent DMF and 0.5% of the total mass of the reactants of photoinitiator 500 are added. The reaction is carried out under ultraviolet light at a wavelength of 365 nm for 12 h. After the reaction is completed, the mixture is transferred to a rotary evaporator and the solvent is removed at a temperature of 80 °C and a vacuum degree of -0.09 MPa. Then, the mixture is dried at a temperature of 80 °C and a vacuum degree of -0.09 MPa for 6 h to obtain bisoxazoline chain extender A.

[0040] Step 3, Preparation of modified recycled polyester melt; Take 90-95 parts of the recycled polyester chips obtained in Step 2, add 2.5-3.5 parts of ultrafine graphite powder, 2-3 parts of PEG-2000, and 0.4-0.6 parts of antibacterial agent; The above materials are placed in a high-speed mixer, with a speed of 1800-2000 r / min and a temperature of 75-80℃, and mixed for 15-20 min. After mixing, the mixture is fed into a twin-screw extruder, with the following temperatures set for each zone: Zone 1 270-275℃, Zone 2 278-282℃, Zone 3 285-288℃, Zone 4 288-290℃, and screw speed of 180-200 r / min. The molten and mixed material is then filtered through a 300-mesh metal mesh melt filter to obtain modified recycled polyester melt.

[0041] The aforementioned ultrafine graphite powder needs to be dispersed in a 0.5wt% CMC aqueous solution beforehand: add the ultrafine graphite powder to a 0.5wt% CMC aqueous solution, set the ultrasonic power to 200W, the ultrasonic time to 30min, and then vacuum dry at 80℃ for 4h.

[0042] The aforementioned antibacterial adjuvant was prepared by uniformly mixing silver-loaded zirconium phosphate and nano zinc oxide at a mass ratio of 4:1.

[0043] Step 4, Pretreatment of recycled nylon raw materials: Select 35-40 kg of waste PA6 fabric (free of polyester and spandex) and 20-25 kg of 78 dtex / 24f nylon waste yarn, sort them, and remove damaged and blended parts; put the sorted raw materials into an ultrasonic cleaning tank, add 150-180 L of 0.2 wt% sodium alginate aqueous solution, set the ultrasonic power to 280 W and the temperature to 50-55 ℃, and ultrasonically clean for 40-45 min; after cleaning, transfer to a dewatering machine, set the speed to 750 r / min, and dewater for 18 min; after dewatering, send to an oven, set the temperature to 105 ℃ and the wind speed to 1.8 m / s, and dry for 2.5 h; after drying, transfer to a fiber shredder, set the speed to 2800 r / min, and shred to a particle size of 0.6-1.2 mm to obtain a nylon waste yarn mixture.

[0044] Step 5, preparation of recycled nylon chips: The nylon waste filament mixture obtained in step 4 is added to the feed hopper of a single screw extruder, and at the same time, bisoxazoline chain extender B is added at an addition amount of 0.55-0.6 wt% of the nylon waste filament mixture.

[0045] The temperatures of each zone of the single-screw extruder are set as follows: feed section 258–260℃, compression section 265–268℃, metering section 272–275℃, and screw speed 140 r / min. After the molten material is extruded from the screw extruder, it enters a vertical melt two-stage pre-filter. The first stage filter element is a 150-mesh pleated multi-layer metal mesh, and the second stage is a 250-mesh pleated multi-layer metal mesh. The filtration pressure is controlled at 10–11 MPa. The filtered recycled nylon melt is extruded through a casting head (2 mm aperture) and cooled in a 23℃ water bath for 2.5 min until solidified. Then it is sent to a slicing machine to obtain recycled nylon chips. According to GB / T12006.1-2009 standard, using 96% sulfuric acid as solvent, the intrinsic viscosity of the recycled nylon chips is measured at 25℃ using an Ubbelohde viscometer to ensure it is 0.88–0.91 dL / g.

[0046] The preparation method of the aforementioned bisoxazoline chain extender B is as follows: Under a nitrogen atmosphere, 2-isopropenyl-2-oxazoline and mercapto-polyethylene glycol-mercapto with a molecular weight of 400 are added to a reaction vessel at a molar ratio of 2.1:1. Then, 3 to 5 times the total mass of DMF solvent and 0.5% of the total mass of photoinitiator 500 are added. The reaction is carried out under ultraviolet light with a wavelength of 365 nm for 12 h. After the reaction is completed, the solvent is removed by rotary evaporator at 80 °C and -0.09 MPa, and then vacuum dried at 80 °C and -0.09 MPa for 6 h to obtain bisoxazoline chain extender B.

[0047] Step 6, Preparation of modified recycled nylon melt; Take 92-96 parts of the recycled nylon chips obtained in Step 5, add 3-3.5 parts of silane coupling agent (KH-550), 2.5-3 parts of titanium fluoride, and 0.3-0.5 parts of antibacterial agent; Put the above materials into a high-speed mixer, set the speed to 1800 r / min, the temperature to 75℃, and mix for 15 min; After mixing, send it into a twin-screw extruder, set the temperature of each zone of the twin-screw extruder as follows: Zone 1 260-265℃, Zone 2 268-272℃, Zone 3 275-278℃, Zone 4 278-280℃, and the screw speed to 180 r / min; Filter the molten and mixed material through a 250-mesh metal mesh melt filter to obtain modified recycled nylon melt.

[0048] Step 7, Composite spinning: The modified recycled polyester melt (core layer) obtained in step 3 and the modified recycled nylon melt (skin layer) obtained in step 6 are respectively fed into two independent spinning boxes of the composite spinning machine.

[0049] Set the spinning box temperature as follows: 288-290℃ for polyester side and 278-280℃ for nylon side.

[0050] The melt volume is controlled by a spinning metering pump, with the modified recycled polyester melt metering pump rotating at 25-28 r / min and the modified recycled nylon melt metering pump rotating at 8-10 r / min, ensuring that the mass ratio of core layer modified recycled polyester to skin layer modified recycled nylon is 75-85:15-25.

[0051] The melt enters the conjugate spinning assembly, wherein the spinneret of the conjugate spinning assembly is orange-petal shaped with 72 holes and a hole diameter of 0.15 mm; a post heater is set at the lower part of the spinneret, and the temperature of the post heater is controlled at 285-290℃.

[0052] The spun nascent yarn is cooled by side-blowing air, with the air velocity controlled at 0.5–0.55 m / s, air temperature at 21–22℃, humidity at 83–85%, and cooling distance at 1.2 m. The side-blowing air is laminar flow, the vertical distance between the air duct and the spinneret is 5 cm, and the air duct diameter is 30 cm.

[0053] After cooling, the nascent yarn is bundled and oiled using Japanese Takemoto high-speed spinning oiling agent with a mass fraction of 12%. The oiling roller speed is controlled at 15 r / min, and the oiling rate is 0.55-0.6%. After oiling, the yarn is drawn and wound with the GR1 linear speed set at 3050-3100 m / min, the GR2 linear speed at 3070-3090 m / min, and the winding angle at 6.5° to obtain pre-oriented yarn (POY).

[0054] Step 8, post-processing and fiber opening; place the POY yarn cake obtained in step 7 into the balancing chamber, control the temperature of the balancing chamber at 25℃ and the relative humidity at 65%, and balance for 24 hours; after balancing, send the yarn cake into the texturing machine, set the texturing temperature to 180~185℃, the draw ratio to 1.5~1.6, and the setting temperature to 120~125℃ to obtain the texturized yarn.

[0055] The textured yarn is placed in an alkaline washing tank, and 5wt% NaOH aqueous solution is added. The bath ratio is controlled at 1:20, the temperature at 80℃, and the stirring speed at 50r / min. The alkaline washing is carried out for 60-65 minutes to achieve fiber opening.

[0056] After alkaline washing, the fibers are transferred to a cold water washing tank, with the water temperature controlled at 25℃ and the bath ratio at 1:30, and stirred for 30 minutes; then they are transferred to an acid washing tank, where 1-1.2 wt% H2SO4 aqueous solution is added, with the water temperature controlled at 25℃ and the bath ratio at 1:25, and stirred for 30 minutes.

[0057] The agitators in the alkaline washing tank and acid washing tank are anchor-type agitators with a diameter 0.8 times the tank diameter and a rotational speed error ≤ ±1 r / min.

[0058] After pickling, the fiber is transferred to a cold water washing tank, with the water temperature controlled at 25°C and the bath ratio at 1:30. The mixture is stirred for 20 minutes until the fiber pH value reaches 7.

[0059] Finally, the fibers were sent into an oven, the oven temperature was set to 105℃, the air speed was 1.5m / s, and the drying time was 4 hours to obtain functional recycled polyester-nylon composite microfiber.

[0060] Step 9, performance testing.

[0061] The performance of the obtained functional recycled polyester-nylon composite microfiber was tested using the following method: (1) Single fiber linear density: According to GB / T14343-2008 standard, 100m of yarn was wound using YG086 yarn length measuring machine and weighed on an electronic balance with an accuracy of 0.0001g to calculate the single fiber linear density.

[0062] (2) Breaking strength and breaking elongation: According to GB / T14344-2021 standard, YG026D-250 fully automatic single yarn strength tester was used, with sample length set to 200mm, stretching speed to 200mm / min, and pre-tension to 0.5cN. The test was performed 5 times and the average value was taken.

[0063] (3) Boiling water shrinkage rate: According to GB / T6505-2017 standard, take a 300mm long fiber sample and mark a 200mm reference distance. Soak it in boiling water for 30min, dry it and measure the change of the reference distance to calculate the boiling water shrinkage rate.

[0064] (4) Thermal decomposition temperature: Using a Diamond TG / DSC thermogravimetric analyzer, the temperature was increased from 25℃ to 600℃ at a rate of 10℃ / min under nitrogen protection, and the temperature corresponding to the maximum weight loss rate was recorded.

[0065] (5) Antibacterial rate: The antibacterial rate against Escherichia coli was tested by shaking method according to GB / T20944.3-2008 standard.

[0066] (6) Specific surface area: The specific surface area was tested using an ASAP2460 BET specific surface area analyzer and the liquid nitrogen adsorption method.

[0067] The present invention will now be described in detail through specific embodiments.

[0068] Example 1 The functional recycled polyester-nylon composite microfiber of this embodiment has a core-skin structure. By mass, the core layer is made of 80 parts of modified recycled polyester and the skin layer is made of 20 parts of modified recycled nylon.

[0069] The core layer modified recycled polyester comprises, by weight, 92 parts of recycled polyester chips; the recycled polyester chips are made from waste PET fabric and waste polyester filaments through sorting, ultrasonic cleaning, crushing, melting and chain extension, filtration and pelletizing, and have an intrinsic viscosity of 0.78 dL / g.

[0070] Three parts of ultrafine graphite powder; the ultrafine graphite powder has a particle size of 500 nm and is ultrasonically dispersed in a 0.5 wt% sodium carboxymethyl cellulose (CMC) aqueous solution.

[0071] 2.5 parts of polyethylene glycol (PEG-2000).

[0072] 0.5 parts of antibacterial adjuvant; the antibacterial adjuvant is made by mixing silver-loaded zirconium phosphate and nano zinc oxide in a mass ratio of 4:1, wherein the particle size of the silver-loaded zirconium phosphate is 200nm and the particle size of the nano zinc oxide is 50nm.

[0073] The modified recycled nylon by weight includes: 94 parts of recycled nylon chips; the recycled nylon chips are made from waste PA6 fabric and waste nylon yarn, which are sorted, ultrasonically cleaned, crushed, melted and extended, filtered and granulated, and have an intrinsic viscosity of 0.88 dL / g.

[0074] 3 parts of silane coupling agent (KH-550).

[0075] 2.5 parts of titanium fluoride; titanium fluoride particle size is 100 nm.

[0076] 0.4 parts of antibacterial additive; the composition of the antibacterial additive is consistent with that used in the core layer modified recycled polyester.

[0077] The functional recycled polyester-nylon composite microfiber has a single fiber linear density of 0.142 dtex, a breaking strength of 6.5 cN / dtex, a breaking elongation of 40.2%, a boiling water shrinkage rate of 12.5%, a thermal decomposition temperature of 345℃, an antibacterial rate of 99.2% against Escherichia coli, and a specific surface area of ​​15200 cm². 2 / g.

[0078] The above-mentioned functional recycled polyester-nylon composite microfiber is prepared by the following method.

[0079] Step 1, pretreatment of recycled polyester raw materials: Select 50kg of waste PET fabric and 30kg of 222dtex / 96f polyester waste yarn that do not contain natural fiber impurities such as spandex and wool, and sort them to remove damaged, unevenly dyed and blended parts.

[0080] The sorted raw materials were placed in an ultrasonic cleaning tank, and 200L of 0.3wt% sodium dodecylbenzenesulfonate aqueous solution was added. The ultrasonic power was set to 300W and the temperature to 55℃. The ultrasonic cleaning was carried out for 45 minutes.

[0081] After cleaning, transfer the raw materials into a dewatering machine, set the speed to 800 r / min, and dewater for 20 minutes.

[0082] After dehydration, the product is placed in an oven at a temperature of 110℃ and a wind speed of 2.0m / s for 3 hours.

[0083] After drying, the material is transferred to a fiber shredder and shredded at a speed of 3000 r / min until the particle size is 0.5-1 mm, thus obtaining a mixture of polyester waste fibers.

[0084] Step 2, preparation of recycled polyester chips: The polyester waste filament mixture obtained in Step 1 is added to the feed hopper of a single screw extruder, and at the same time, bisoxazoline chain extender A is added at an addition amount of 0.5 wt% of the polyester waste filament mixture.

[0085] The temperatures of each zone of the single-screw extruder were set as follows: 262℃ for the feeding section, 275℃ for the compression section, and 282℃ for the metering section. The screw speed was 150 r / min. After the melt was extruded from the screw extruder, it entered a vertical melt two-stage pre-filter. The first stage filter element was a 100-mesh pleated multi-layer metal mesh, and the second stage was a 200-mesh pleated multi-layer metal mesh. The filtration pressure was controlled at 12 MPa. The filtered recycled polyester melt was extruded through a 2 mm diameter casting head and cooled in a 25℃ water bath for 3 minutes until solidified. Then it was sent to a slicing machine to obtain recycled polyester chips. The intrinsic viscosity was measured to be 0.78 dL / g according to the aforementioned intrinsic viscosity test method.

[0086] The preparation method of bisoxazoline chain extender A is as follows: 2-isopropenyl-2-oxazoline and mercapto-polyethylene glycol-mercapto with a molecular weight of 200 are added to a reaction vessel at a molar ratio of 2.1:1 under a nitrogen atmosphere. Then, solvent DMF of 3 times the total mass of the reactants and photoinitiator 500 of 0.5% of the total mass of the reactants are added. The reaction is carried out under ultraviolet light at a wavelength of 365 nm for 12 h. After the reaction is completed, the mixture is transferred to a rotary evaporator and the solvent is removed under a temperature of 80℃ and a vacuum degree of -0.09 MPa. Subsequently, it is vacuum dried for 6 h under a temperature of 80℃ and a vacuum degree of -0.09 MPa.

[0087] Step 3, Preparation of modified recycled polyester melt: Take 92 kg of recycled polyester chips obtained in Step 2, add 3 kg of ultrafine graphite powder, 2.5 kg of PEG-2000, and 0.5 kg of antibacterial additives that have been ultrasonically dispersed in 0.5 wt% CMC aqueous solution.

[0088] The above materials were placed in a high-speed mixer, with a speed of 2000 r / min and a temperature of 80℃, and mixed for 20 min. After mixing, the mixture was fed into a twin-screw extruder, with the following temperatures set for each zone: Zone 1 270℃, Zone 2 278℃, Zone 3 285℃, Zone 4 288℃, and screw speed of 200 r / min. The molten and mixed materials were then filtered through a 300-mesh metal mesh melt filter to obtain modified recycled polyester melt.

[0089] Step 4, pretreatment of recycled nylon raw materials: Select 40kg of waste PA6 fabric and 20kg of 78dtex / 24f nylon waste yarn that do not contain polyester or spandex components, sort them, and remove damaged and blended parts.

[0090] The sorted raw materials were placed in an ultrasonic cleaning tank, and 150L of 0.2wt% sodium alginate aqueous solution was added. The ultrasonic power was set to 280W and the temperature to 50℃. The ultrasonic cleaning was carried out for 40 minutes.

[0091] After cleaning, transfer to a dehydrator, set the speed to 750 r / min, and dehydrate for 18 minutes.

[0092] After dehydration, the product is placed in an oven at a temperature of 105℃ and a wind speed of 1.8m / s for 2.5 hours.

[0093] After drying, the material is transferred to a fiber shredder and shredded at a speed of 2800 r / min until the particle size is 0.6-1.2 mm, thus obtaining a mixture of nylon waste fibers.

[0094] Step 5, Preparation of recycled nylon chips: The nylon waste filament mixture obtained in Step 4 is added to the feed hopper of a single-screw extruder, and bisoxazoline chain extender B is added at a rate of 0.55 wt% of the nylon waste filament mixture. The temperatures of each zone of the single-screw extruder are set as follows: feed section 258℃, compression section 265℃, metering section 272℃, and screw speed 140 r / min. After the melt is extruded from the screw extruder, it enters a vertical melt two-stage pre-filter. The first stage filter element is a 150-mesh pleated multi-layer metal mesh, and the second stage is a 250-mesh pleated multi-layer metal mesh. The filtration pressure is controlled at 10 MPa. The filtered recycled nylon melt is extruded through a 2 mm diameter casting head and cooled in a 23℃ water bath for 2.5 min until solidified. Then it is sent to a slicing machine to obtain recycled nylon chips. The intrinsic viscosity is measured to be 0.88 dL / g according to the aforementioned intrinsic viscosity test method.

[0095] The preparation method of bisoxazoline chain extender B is as follows: under a nitrogen atmosphere, 2-isopropenyl-2-oxazoline and mercapto-polyethylene glycol-mercapto with a molecular weight of 400 are added to a reaction vessel at a molar ratio of 2.1:1. Then, DMF solvent with a total mass of 3 times the total mass of the reactants and photoinitiator 500 with a total mass of 0.5% of the total mass of the reactants are added. The reaction is carried out under ultraviolet light with a wavelength of 365 nm for 12 h. After the reaction is completed, the solvent is removed by rotary evaporator at 80 °C and -0.09 MPa. Then, the product is vacuum dried at 80 °C and -0.09 MPa for 6 h.

[0096] Step 6, Preparation of modified recycled nylon melt; Take 94 kg of recycled nylon chips obtained in step 5, add 3 kg of silane coupling agent (KH-550), 2.5 kg of titanium fluoride with a particle size of 100 nm, and 0.4 kg of antibacterial agent. The composition of the antibacterial agent is the same as that in step 3.

[0097] The above materials were placed in a high-speed mixer, with a speed of 1800 r / min and a temperature of 75℃, and mixed for 15 min. After mixing, the mixture was fed into a twin-screw extruder, with the following temperatures set for each zone: Zone 1 260℃, Zone 2 268℃, Zone 3 275℃, Zone 4 278℃, and screw speed of 180 r / min. The molten and mixed material was then filtered through a 250-mesh metal mesh melt filter to obtain modified recycled nylon melt.

[0098] Step 7, Composite spinning; The modified recycled polyester melt (core layer) obtained in Step 3 and the modified recycled nylon melt (skin layer) obtained in Step 6 are respectively fed into two independent spinning boxes of the composite spinning machine, and the spinning box temperatures are set as follows: 288℃ for the polyester side and 278℃ for the nylon side.

[0099] The melt volume is controlled by a spinning metering pump, with the modified recycled polyester melt metering pump rotating at 25 r / min and the modified recycled nylon melt metering pump rotating at 8 r / min, ensuring that the mass ratio of the core layer to the skin layer is 80:20.

[0100] The melt enters the conjugate spinning assembly, which has an orange-petal-shaped spinneret with 72 holes and a hole diameter of 0.15 mm. A post heater is installed at the bottom of the spinneret, and the temperature of the post heater is controlled at 285°C.

[0101] The spun nascent yarn is cooled by side blowing, with the side blowing speed controlled at 0.5 m / s, wind temperature at 21℃, humidity at 83%, and cooling distance at 1.2 m.

[0102] After cooling, the nascent yarn is bundled and oiled using Japanese Takemoto high-speed spinning oiling agent with a mass fraction of 12%. The oiling roller speed is controlled at 15 r / min, and the oiling rate is 0.55%. After oiling, the yarn is drawn and wound with the GR1 linear speed set at 3050 m / min, the GR2 linear speed at 3070 m / min, and the winding angle at 6.5° to obtain pre-oriented yarn (POY).

[0103] Step 8, post-processing and fiber opening: Place the POY yarn cake obtained in step 7 into the balancing chamber, control the temperature of the balancing chamber at 25℃ and the relative humidity at 65%, and equilibrate for 24 hours.

[0104] After balancing, the yarn cake is fed into a texturing machine, and the texturing temperature is set to 180℃, the draw ratio to 1.5, and the setting temperature to 120℃ to obtain texturized yarn.

[0105] The textured yarn is placed in an alkaline washing tank, and 5wt% NaOH aqueous solution is added. The bath ratio is controlled at 1:20, the temperature at 80℃, and the stirring speed at 50r / min. The alkaline washing is carried out for 60min to achieve fiber opening.

[0106] After alkaline washing, the fibers are transferred to a cold water washing tank, with the water temperature controlled at 25℃ and the bath ratio at 1:30, and stirred for 30 minutes; then they are transferred to an acid washing tank, where 1wt% H2SO4 aqueous solution is added, with the water temperature controlled at 25℃ and the bath ratio at 1:25, and stirred for 30 minutes.

[0107] After pickling, the fiber is transferred to a cold water washing tank, with the water temperature controlled at 25°C and the bath ratio at 1:30. The mixture is stirred for 20 minutes until the fiber pH value reaches 7.

[0108] Finally, the fibers were sent into an oven, the oven temperature was set to 105℃, the air speed was 1.5m / s, and the drying time was 4 hours to obtain functional recycled polyester-nylon composite microfiber.

[0109] Step 9, performance testing.

[0110] The performance of the obtained functional recycled polyester-nylon composite microfiber was tested using the following method, and the results are as follows: Single fiber linear density: According to GB / T14343-2008 standard, 100m of yarn was wound using a YG086 yarn length measuring machine and weighed on an electronic balance with an accuracy of 0.0001g. The calculated single fiber linear density was 0.142dtex.

[0111] Breaking strength and elongation at break: According to GB / T14344-2021 standard, using a YG026D-250 fully automatic single yarn tensile testing machine, the sample length was set to 200mm, the tensile speed to 200mm / min, the pre-tension to 0.5cN, and the average value was taken after 5 tests. The breaking strength was 6.5cN / dtex and the elongation at break was 40.2%.

[0112] Boiling water shrinkage rate: According to GB / T6505-2017 standard, a 300mm long fiber sample was taken and marked with a 200mm reference distance. The sample was soaked in boiling water for 30 minutes, dried, and the change in the reference distance was measured. The boiling water shrinkage rate was calculated to be 12.5%.

[0113] Thermal decomposition temperature: Using a Diamond-type TG / DSC thermogravimetric analyzer, the temperature was increased from 25℃ to 600℃ at a rate of 10℃ / min under nitrogen protection. The temperature corresponding to the maximum weight loss rate was recorded, and the thermal decomposition temperature was found to be 345℃.

[0114] Antibacterial rate: According to GB / T20944.3-2008 standard, the antibacterial rate against Escherichia coli was tested by the shaking method, and the antibacterial rate was 99.2%.

[0115] Specific surface area: The specific surface area was measured using an ASAP2460 BET specific surface area analyzer and the liquid nitrogen adsorption method, yielding a value of 15200 cm². 2 / g.

[0116] Example 2 The functional recycled polyester-nylon composite microfiber of this embodiment has a core-skin structure. By mass, the core layer is made of 82 parts of modified recycled polyester and the skin layer is made of 18 parts of modified recycled nylon.

[0117] The core layer modified recycled polyester comprises 93 parts by weight of recycled polyester chips; the recycled polyester chips are made from waste PET fabric and waste polyester filaments through sorting, ultrasonic cleaning, crushing, melting and chain extension, filtration and pelletizing, and have an intrinsic viscosity of 0.79 dL / g.

[0118] 3.2 parts of ultrafine graphite powder; the ultrafine graphite powder has a particle size of 650 nm and is ultrasonically dispersed by 0.5 wt% CMC aqueous solution.

[0119] 2.8 parts of polyethylene glycol (PEG-2000).

[0120] 0.55 parts of antibacterial adjuvant; the antibacterial adjuvant is made by mixing silver-loaded zirconium phosphate and nano zinc oxide in a mass ratio of 4:1, wherein the particle size of the silver-loaded zirconium phosphate is 250 nm and the particle size of the nano zinc oxide is 65 nm.

[0121] The modified recycled nylon comprises 95 parts by weight of recycled nylon chips. The recycled nylon chips are made from waste PA6 fabric and waste nylon yarn through sorting, ultrasonic cleaning, crushing, melting and chain extension, filtration and pelletizing. The intrinsic viscosity is 0.90 dL / g.

[0122] 3.2 parts of silane coupling agent (KH-550).

[0123] 2.8 parts of titanium fluoride; the titanium fluoride has a particle size of 125 nm.

[0124] 0.45 parts of antibacterial additive; the composition of the antibacterial additive is consistent with that used in the core layer modified recycled polyester.

[0125] The functional recycled polyester-nylon composite microfiber has a single fiber linear density of 0.145 dtex, a breaking strength of 6.7 cN / dtex, a breaking elongation of 40.8%, a boiling water shrinkage rate of 13.0%, a thermal decomposition temperature of 347℃, an antibacterial rate of 99.3% against Escherichia coli, and a specific surface area of ​​15500 cm². 2 / g.

[0126] The above-mentioned functional recycled polyester-nylon composite microfiber is prepared by the following method.

[0127] Step 1, pretreatment of recycled polyester raw materials: Select 45kg of waste PET fabric and 35kg of 222dtex / 96f polyester waste yarn that do not contain natural fiber impurities such as spandex and wool, and sort them to remove damaged, unevenly dyed and blended parts.

[0128] The sorted raw materials were placed in an ultrasonic cleaning tank, and 190L of 0.3wt% sodium dodecylbenzenesulfonate aqueous solution was added. The ultrasonic power was set to 300W and the temperature to 56℃. The ultrasonic cleaning was carried out for 48 minutes.

[0129] After cleaning, the raw materials are transferred to a dewatering machine, set to a speed of 780 r / min, and dewatered for 19 minutes.

[0130] After dehydration, the product is placed in an oven with a temperature of 108℃, a wind speed of 1.9m / s, and dried for 2.8 hours.

[0131] After drying, the material is transferred to a fiber shredder and shredded at a speed of 2900 r / min until the particle size is 0.6-1 mm, thus obtaining a mixture of polyester waste fibers.

[0132] Step 2, preparation of recycled polyester chips: The polyester waste filament mixture obtained in Step 1 is added to the feed hopper of a single-screw extruder, and bisoxazoline chain extender A is added at an amount of 0.52 wt% of the polyester waste filament mixture. The preparation method of bisoxazoline chain extender A is the same as in Example 1.

[0133] The temperatures of each zone of the single-screw extruder were set as follows: 263℃ for the feeding section, 276℃ for the compression section, and 283℃ for the metering section, with a screw speed of 145 r / min. After the melt was extruded from the screw extruder, it entered a vertical melt two-stage pre-filter. The first stage filter element was a 100-mesh pleated multi-layer metal mesh, and the second stage was a 200-mesh pleated multi-layer metal mesh. The filtration pressure was controlled at 11.5 MPa. The filtered recycled polyester melt was extruded through a 2 mm diameter casting head and cooled in a 24℃ water bath for 2.8 min until solidified. Then it was sent to a slicing machine to obtain recycled polyester chips. The intrinsic viscosity was measured to be 0.79 dL / g according to the aforementioned intrinsic viscosity test method.

[0134] Step 3, Preparation of modified recycled polyester melt: Take 93 kg of recycled polyester chips obtained in Step 2, and add 3.2 kg of ultrafine graphite powder, 2.8 kg of PEG-2000, and 0.55 kg of antibacterial agent that have been ultrasonically dispersed in 0.5 wt% CMC aqueous solution.

[0135] The above materials were placed in a high-speed mixer, with a speed of 1900 r / min and a temperature of 78℃, and mixed for 18 min. After mixing, the mixture was fed into a twin-screw extruder, with the following temperatures set for each zone: Zone 1 272℃, Zone 2 280℃, Zone 3 286℃, Zone 4 289℃, and screw speed of 190 r / min. The molten and mixed material was then filtered through a 300-mesh metal mesh melt filter to obtain modified recycled polyester melt.

[0136] Step 4, pretreatment of recycled nylon raw materials: Select 38kg of waste PA6 fabric and 22kg of 78dtex / 24f nylon waste yarn that do not contain polyester or spandex components, sort them, and remove damaged and blended parts.

[0137] The sorted raw materials were placed in an ultrasonic cleaning tank, and 165L of 0.2wt% sodium alginate aqueous solution was added. The ultrasonic power was set to 280W and the temperature to 52℃. The ultrasonic cleaning was carried out for 42 minutes.

[0138] After cleaning, transfer to a dehydrator, set the speed to 750 r / min, and dehydrate for 18 minutes.

[0139] After dehydration, the product is placed in an oven at a temperature of 105℃ and a wind speed of 1.8m / s for 2.6 hours.

[0140] After drying, the material is transferred to a fiber shredder and shredded at a speed of 2800 r / min until the particle size is 0.8-1.1 mm, thus obtaining a mixture of nylon waste fibers.

[0141] Step 5, preparation of recycled nylon chips: The nylon waste filament mixture obtained in Step 4 is added to the feed hopper of a single-screw extruder, and simultaneously added at an amount of 0.58 wt% of the nylon waste filament mixture. The preparation method of bisoxazoline chain extender B is the same as in Example 1.

[0142] The temperatures of each zone of the single-screw extruder were set as follows: 259℃ for the feeding section, 266℃ for the compression section, and 273℃ for the metering section, with a screw speed of 140 r / min. After the melt was extruded from the screw extruder, it entered a vertical melt two-stage pre-filter. The first stage filter element was a 150-mesh pleated multi-layer metal mesh, and the second stage was a 250-mesh pleated multi-layer metal mesh. The filtration pressure was controlled at 10.5 MPa. The filtered recycled nylon melt was extruded through a 2 mm diameter casting head and cooled in a 23℃ water bath for 2.5 min until solidified. Then it was sent to a slicing machine to obtain recycled nylon chips. The intrinsic viscosity was measured to be 0.90 dL / g according to the aforementioned intrinsic viscosity test method.

[0143] Step 6: Preparation of modified recycled nylon melt; Take 95 kg of recycled nylon chips obtained in Step 5, and add 3.2 kg of silane coupling agent (KH-550), 2.8 kg of titanium fluoride with a particle size of 125 nm, and 0.45 kg of antibacterial additive. The composition of the antibacterial additive is the same as that in Step 3.

[0144] The above materials were placed in a high-speed mixer, with a speed of 1800 r / min and a temperature of 75℃, and mixed for 15 min. After mixing, the mixture was fed into a twin-screw extruder, with the following temperatures set for each zone: Zone 1 262℃, Zone 2 270℃, Zone 3 276℃, Zone 4 279℃, and screw speed of 180 r / min. The molten and mixed material was then filtered through a 250-mesh metal mesh melt filter to obtain modified recycled nylon melt.

[0145] Step 7, Composite spinning; The modified recycled polyester melt (core layer) obtained in Step 3 and the modified recycled nylon melt (skin layer) obtained in Step 6 are respectively fed into two independent spinning boxes of the composite spinning machine, and the spinning box temperatures are set as follows: 289℃ for the polyester side and 279℃ for the nylon side.

[0146] The melt volume is controlled by a spinning metering pump, with the modified recycled polyester melt metering pump rotating at 26 r / min and the modified recycled nylon melt metering pump rotating at 9 r / min, ensuring that the mass ratio of the core layer to the skin layer is 82:18.

[0147] The melt enters the conjugate spinning assembly, and a post heater is installed below the spinneret, with the temperature of the post heater controlled at 287°C.

[0148] The spun nascent yarn is cooled by side blowing, with the side blowing speed controlled at 0.52 m / s, wind temperature at 21.5℃, humidity at 84%, and cooling distance at 1.2 m.

[0149] After cooling, the nascent yarn is bundled and oiled using Japanese Takemoto high-speed spinning oiling agent with a mass fraction of 12%. The oiling roller speed is controlled at 15 r / min, and the oiling rate is 0.58%. After oiling, the yarn is drawn and wound with the GR1 linear speed set at 3070 m / min, the GR2 linear speed at 3080 m / min, and the winding angle at 6.5° to obtain pre-oriented yarn (POY).

[0150] Step 8, post-processing and fiber opening: Place the POY yarn cake obtained in step 7 into the balancing chamber, control the temperature of the balancing chamber at 25℃ and the relative humidity at 65%, and equilibrate for 24 hours.

[0151] After balancing, the yarn cake is fed into a texturing machine, and the texturing temperature is set to 182℃, the draw ratio to 1.55, and the setting temperature to 122℃ to obtain texturized yarn.

[0152] The textured yarn is placed in an alkaline washing tank, and 5wt% NaOH aqueous solution is added. The bath ratio is controlled at 1:20, the temperature at 80℃, and the stirring speed at 50r / min. The alkaline washing is carried out for 62 minutes to achieve fiber opening.

[0153] After alkaline washing, the fibers are transferred to a cold water washing tank, with the water temperature controlled at 25℃ and the bath ratio at 1:30, and stirred for 30 minutes; then they are transferred to an acid washing tank, where 1.1wt% H2SO4 aqueous solution is added, with the water temperature controlled at 25℃ and the bath ratio at 1:25, and stirred for 30 minutes.

[0154] After pickling, the fiber is transferred to a cold water washing tank, with the water temperature controlled at 25°C and the bath ratio at 1:30. The mixture is stirred for 20 minutes until the fiber pH value reaches 7.

[0155] Finally, the fibers were sent into an oven, the oven temperature was set to 105℃, the air speed was 1.5m / s, and the drying time was 4 hours to obtain functional recycled polyester-nylon composite microfiber.

[0156] Step 9, performance testing.

[0157] The performance of the obtained functional recycled polyester-nylon composite microfiber was tested using the same testing method as in Example 1, and the results are as follows: Single fiber linear density: 0.145 dtex.

[0158] Fracture strength and elongation at break: Fracture strength 6.7 cN / dtex, elongation at break 40.8%.

[0159] Boiling water shrinkage rate: 13.0%.

[0160] Thermal decomposition temperature: 347℃.

[0161] Antibacterial rate: 99.3% (against Escherichia coli).

[0162] Specific surface area: 15500cm² 2 / g.

[0163] Example 3 The functional recycled polyester-nylon composite microfiber of this embodiment has a core-skin structure. By mass, the core layer is made of 85 parts of modified recycled polyester and the skin layer is made of 15 parts of modified recycled nylon.

[0164] The core layer modified recycled polyester comprises 95 parts by weight of recycled polyester chips; the recycled polyester chips are made from waste PET fabric and waste polyester filaments through sorting, ultrasonic cleaning, crushing, melting and chain extension, filtration and pelletizing, and have an intrinsic viscosity of 0.81 dL / g.

[0165] 3.5 parts of ultrafine graphite powder; the ultrafine graphite powder has a particle size of 800 nm and is ultrasonically dispersed by 0.5 wt% CMC aqueous solution.

[0166] Three parts of polyethylene glycol (PEG-2000).

[0167] Antibacterial adjuvant: 0.6 parts; the antibacterial adjuvant is made by mixing silver-loaded zirconium phosphate and nano zinc oxide in a mass ratio of 4:1, wherein the particle size of the silver-loaded zirconium phosphate is 300 nm and the particle size of the nano zinc oxide is 80 nm.

[0168] The modified recycled nylon comprises 96 parts by weight of recycled nylon chips. The recycled nylon chips are made from waste PA6 fabric and waste nylon yarn through sorting, ultrasonic cleaning, crushing, melting and chain extension, filtration and pelletizing. The intrinsic viscosity is 0.91 dL / g.

[0169] 3.5 parts of silane coupling agent (KH-550).

[0170] Three parts of titanium fluoride; the particle size of titanium fluoride is 150 nm.

[0171] 0.5 parts of antibacterial additive; the composition of the antibacterial additive is consistent with that used in the core layer modified recycled polyester.

[0172] The functional recycled polyester-nylon composite microfiber has a single fiber linear density of 0.150 dtex, a breaking strength of 7.0 cN / dtex, a breaking elongation of 42.0%, a boiling water shrinkage rate of 14.0%, a thermal decomposition temperature of 350℃, an antibacterial rate of 99.5% against Escherichia coli, and a specific surface area of ​​16000 cm². 2 / g.

[0173] The above-mentioned functional recycled polyester-nylon composite microfiber is prepared by the following method.

[0174] Step 1, pretreatment of recycled polyester raw materials: Select 40kg of waste PET fabric and 40kg of 222dtex / 96f polyester waste yarn that do not contain natural fiber impurities such as spandex and wool, and sort them to remove damaged, unevenly dyed and blended parts.

[0175] The sorted raw materials were placed in an ultrasonic cleaning tank, and 180L of 0.3wt% sodium dodecylbenzenesulfonate aqueous solution was added. The ultrasonic power was set to 300W and the temperature to 58℃. The ultrasonic cleaning was carried out for 50 minutes.

[0176] After cleaning, transfer the raw materials into a dewatering machine, set the speed to 800 r / min, and dewater for 20 minutes.

[0177] After dehydration, the product is placed in an oven at a temperature of 110℃ and a wind speed of 2.0m / s for 3 hours.

[0178] After drying, the material is transferred to a fiber shredder and shredded at a speed of 3000 r / min until the particle size is 0.8-1.2 mm, thus obtaining a mixture of polyester waste fibers.

[0179] Step 2, preparation of recycled polyester chips: The polyester waste filament mixture obtained in Step 1 is added to the feed hopper of a single-screw extruder, and bisoxazoline chain extender A is added at an amount of 0.55 wt% of the polyester waste filament mixture. The preparation method of bisoxazoline chain extender A is the same as in Example 1.

[0180] The temperatures of each zone of the single-screw extruder were set as follows: 265℃ for the feeding section, 278℃ for the compression section, and 285℃ for the metering section. The screw speed was 140 r / min. After the melt was extruded from the screw extruder, it entered a vertical melt two-stage pre-filter. The first stage filter element was a 100-mesh pleated multi-layer metal mesh, and the second stage was a 200-mesh pleated multi-layer metal mesh. The filtration pressure was controlled at 11 MPa. The filtered recycled polyester melt was extruded through a 2 mm diameter casting head and cooled in a 23℃ water bath for 2.5 min until solidified. Then it was sent to a slicing machine to obtain recycled polyester chips. The intrinsic viscosity was measured to be 0.81 dL / g according to the aforementioned intrinsic viscosity test method.

[0181] Step 3, Preparation of modified recycled polyester melt: Take 95 kg of recycled polyester chips obtained in Step 2, add 3.5 kg of ultrafine graphite powder that has been ultrasonically dispersed by 0.5 wt% CMC aqueous solution, 3 kg of PEG-2000, and 0.6 kg of antibacterial additive.

[0182] The above materials were placed in a high-speed mixer, with a speed of 2000 r / min and a temperature of 80℃, and mixed for 20 min. After mixing, the mixture was fed into a twin-screw extruder, with the following temperatures set for each zone: Zone 1 275℃, Zone 2 282℃, Zone 3 288℃, Zone 4 290℃, and screw speed of 200 r / min. The molten and mixed materials were then filtered through a 300-mesh metal mesh melt filter to obtain modified recycled polyester melt.

[0183] Step 4, pretreatment of recycled nylon raw materials: Select 35kg of waste PA6 fabric and 25kg of 78dtex / 24f nylon waste yarn that do not contain polyester or spandex components, sort them, and remove damaged and blended parts.

[0184] The sorted raw materials were placed in an ultrasonic cleaning tank, and 180L of 0.2wt% sodium alginate aqueous solution was added. The ultrasonic power was set to 280W and the temperature to 55℃. The ultrasonic cleaning was carried out for 45 minutes.

[0185] After cleaning, transfer to a dehydrator, set the speed to 750 r / min, and dehydrate for 18 minutes.

[0186] After dehydration, the product is placed in an oven at a temperature of 105℃ and a wind speed of 1.8m / s for 2.7 hours.

[0187] After drying, the material is transferred to a fiber shredder and shredded at a speed of 2800 r / min until the particle size is 1.0-1.2 mm, thus obtaining a mixture of nylon waste fibers.

[0188] Step 5, Preparation of recycled nylon chips: The nylon waste filament mixture obtained in Step 4 is added to the feed hopper of a single-screw extruder, and bisoxazoline chain extender B is added at an amount of 0.6 wt% of the nylon waste filament mixture. The preparation method of bisoxazoline chain extender B is the same as in Example 1.

[0189] The temperatures of each zone of the single-screw extruder were set as follows: 260℃ for the feeding section, 268℃ for the compression section, and 275℃ for the metering section. The screw speed was 140 r / min. After the melt was extruded from the screw extruder, it entered a vertical melt two-stage pre-filter. The first stage filter element was a 150-mesh pleated multi-layer metal mesh, and the second stage was a 250-mesh pleated multi-layer metal mesh. The filtration pressure was controlled at 11 MPa. The filtered recycled nylon melt was extruded through a 2 mm diameter casting head and cooled in a 23℃ water bath for 2.5 min until solidified. Then it was sent to a slicing machine to obtain recycled nylon chips. The intrinsic viscosity was measured to be 0.91 dL / g according to the aforementioned intrinsic viscosity test method.

[0190] Step 6, Preparation of modified recycled nylon melt; Take 96 kg of recycled nylon chips obtained in Step 5, add 3.5 kg of silane coupling agent (KH-550), 3 kg of titanium fluoride with a particle size of 150 nm, and 0.5 kg of antibacterial agent. The composition of the antibacterial agent is the same as that in Step 3.

[0191] The above materials were placed in a high-speed mixer, with a speed of 1800 r / min and a temperature of 75℃, and mixed for 15 min. After mixing, the mixture was fed into a twin-screw extruder, with the following temperatures set for each zone: Zone 1 265℃, Zone 2 272℃, Zone 3 278℃, Zone 4 280℃, and screw speed of 180 r / min. The molten and mixed material was then filtered through a 250-mesh metal mesh melt filter to obtain modified recycled nylon melt.

[0192] Step 7, Composite spinning; The modified recycled polyester melt (core layer) obtained in Step 3 and the modified recycled nylon melt (skin layer) obtained in Step 6 are respectively fed into two independent spinning boxes of the composite spinning machine, and the spinning box temperature is set to 290℃ for the polyester side and 280℃ for the nylon side.

[0193] The melt volume is controlled by a spinning metering pump, with the modified recycled polyester melt metering pump rotating at 28 r / min and the modified recycled nylon melt metering pump rotating at 10 r / min, ensuring that the mass ratio of the core layer to the skin layer is 85:15.

[0194] The melt enters the conjugate spinning assembly, and a post heater is installed below the spinneret, with the temperature of the post heater controlled at 290°C.

[0195] The spun nascent yarn is cooled by side blowing, with the side blowing speed controlled at 0.55 m / s, wind temperature at 22℃, humidity at 85%, and cooling distance at 1.2 m.

[0196] After cooling, the nascent yarn is bundled and oiled using Japanese Takemoto high-speed spinning oiling agent with a mass fraction of 12%. The oiling roller speed is controlled at 15 r / min, and the oiling rate is 0.6%. After oiling, the yarn is drawn and wound with the GR1 linear speed set at 3100 m / min, the GR2 linear speed at 3090 m / min, and the winding angle at 6.5° to obtain pre-oriented yarn (POY).

[0197] Step 8, post-processing and fiber opening: Place the POY yarn cake obtained in step 7 into the balancing chamber, control the temperature of the balancing chamber at 25℃ and the relative humidity at 65%, and equilibrate for 24 hours.

[0198] After balancing, the yarn cake is fed into a texturing machine, and the texturing temperature is set to 185℃, the draw ratio to 1.6, and the setting temperature to 125℃ to obtain texturized yarn.

[0199] The textured yarn is placed in an alkaline washing tank, and 5wt% NaOH aqueous solution is added. The bath ratio is controlled at 1:20, the temperature at 80℃, and the stirring speed at 50r / min. The yarn is washed for 65 minutes to achieve fiber opening.

[0200] After alkaline washing, the fibers are transferred to a cold water washing tank, with the water temperature controlled at 25℃ and the bath ratio at 1:30, and stirred for 30 minutes; then they are transferred to an acid washing tank, where 1.2wt% H2SO4 aqueous solution is added, with the water temperature controlled at 25℃ and the bath ratio at 1:25, and stirred for 30 minutes.

[0201] After pickling, the fiber is transferred to a cold water washing tank, with the water temperature controlled at 25°C and the bath ratio at 1:30. The mixture is stirred for 20 minutes until the fiber pH value reaches 7.

[0202] Finally, the fibers were sent into an oven, the oven temperature was set to 105℃, the air speed was 1.5m / s, and the drying time was 4 hours to obtain functional recycled polyester-nylon composite microfiber.

[0203] Step 9, performance testing.

[0204] The performance of the obtained functional recycled polyester-nylon composite microfiber was tested using the same testing method as in Example 1, and the results are as follows: Single fiber linear density: 0.150 dtex.

[0205] Fracture strength and elongation at break: Fracture strength 7.0 cN / dtex, elongation at break 42.0%.

[0206] Boiling water shrinkage rate: 14.0%.

[0207] Thermal decomposition temperature: 350℃.

[0208] Antibacterial rate: 99.5% (against Escherichia coli).

[0209] Specific surface area: 16000cm² 2 / g.

[0210] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A functional regenerated polyester-polyamide composite microfiber, characterized by, The modified regenerated polyester is taken as the core layer, and the modified regenerated nylon is taken as the skin layer; the modified regenerated polyester accounts for 75-85 parts by mass, and the modified regenerated nylon accounts for 15-25 parts by mass; The modified regenerated polyester comprises 90-95 parts of regenerated polyester chips, 2.5-3.5 parts of superfine graphite powder, 2-3 parts of polyethylene glycol, and 0.4-0.6 parts of an antibacterial additive by mass; The regenerated polyester chips are prepared from waste PET fabric and polyester waste silk as raw materials through sorting, ultrasonic cleaning, crushing, melt chain extension, and filtering and granulation, and the mass ratio of the waste PET fabric to the polyester waste silk is 4-5:3-4; The regenerated nylon chips are prepared from waste PA6 fabric and nylon waste silk as raw materials through sorting, ultrasonic cleaning, crushing, melt chain extension, and filtering and granulation, and the mass ratio of the waste PA6 fabric to the nylon waste silk is 7-8:4-5.

2. The functional regenerated polyester-polyamide composite microfiber according to claim 1, wherein, The antibacterial additive is prepared by mixing silver-loaded zirconium phosphate and nano zinc oxide at a mass ratio of 4:

1.

3. The functional regenerated polyester-polyamide composite microfiber according to claim 1, wherein, The modified regenerated nylon comprises 92-96 parts of regenerated nylon chips, 3-3.5 parts of a silane coupling agent, 2.5-3 parts of titanium fluoride, and 0.3-0.5 parts of the antibacterial additive by mass.

4. The functional regenerated polyester-polyamide composite microfiber according to claim 1, wherein the polyester-polyamide composite microfiber is characterized by, The superfine graphite powder has a particle size of 500-800 nm and is subjected to ultrasonic dispersion treatment with 0.5wt% sodium carboxymethyl cellulose aqueous solution.

5. The method for preparing functional recycled polyester-nylon composite microfiber according to claim 1, characterized in that, The method comprises the following steps: Step 1: Preprocessing of regenerated polyester raw materials; the waste PET fabric and polyester waste silk are weighed according to the formula, and after impurity removal, they are put into an ultrasonic cleaning tank and cleaned by adding 0.3wt% sodium dodecyl benzene sulfonate aqueous solution; after cleaning, dehydration, drying, and slitting, the polyester waste silk mixture is obtained; Step 2: Preparation of regenerated polyester chips; the polyester waste silk mixture obtained in step 1 is added to the feeding hopper of a single screw extruder, and bisoxazoline chain extender A is added at an amount of 0.5-0.55wt% of the polyester waste silk mixture; after the melt is extruded from the screw extruder, it enters a vertical melt double-stage pre-filter, and then is extruded through a casting head, solidified, and slitted to obtain regenerated polyester chips; Step 3: Preparation of modified regenerated polyester melt; 90-95 parts of the regenerated polyester chips obtained in step 2, 2.5-3.5 parts of superfine graphite powder, 2-3 parts of polyethylene glycol, and 0.4-0.6 parts of the antibacterial additive are mixed and then fed into a double screw extruder; the melt after melt mixing is filtered through a metal mesh melt filter to obtain a modified regenerated polyester melt; Step 4: Preprocessing of regenerated nylon raw materials; the PA6 fabric and nylon waste silk are weighed according to the formula, and after impurity removal, they are put into an ultrasonic cleaning tank and cleaned by adding 0.2wt% sodium alginate aqueous solution; after cleaning, dehydration, drying, and slitting, the nylon waste silk mixture is obtained; Step 5: Preparation of regenerated nylon chips; the nylon waste silk mixture obtained in step 4 is added to the feeding hopper of a single screw extruder, and bisoxazoline chain extender B is added at an amount of 0.55-0.6wt% of the nylon waste silk mixture; after the melt is extruded from the screw extruder, it enters a vertical melt double-stage pre-filter, and then is extruded through a casting head, solidified, and slitted to obtain regenerated nylon chips; Step 6, preparation of modified regenerated nylon 6 melt; take 92-96 parts of the regenerated nylon chips obtained in step 5, add 3-3.5 parts of silane coupling agent, 2.5-3 parts of titanium fluoride, and 0.3-0.5 parts of antibacterial additive, mix and then send into a double screw extruder, filter the melt after melt mixing through a metal mesh melt filter to obtain a modified regenerated nylon 6 melt; Step 7, composite spinning; send the modified regenerated polyester melt obtained in step 3 and the modified regenerated nylon 6 melt obtained in step 6 into two independent spinning boxes of a composite spinning machine; the melt enters a conjugate spinning assembly, and the primary filaments after cooling are bundled, oiled, and wound to obtain a POY cake; Step 8, post-treatment and opening; the POY cake is subjected to balance, elastic recovery, and then sequentially subjected to alkali washing, water washing, acid washing, and water washing, and then dried to obtain a functional regenerated polyester-nylon composite ultrafine fiber.

6. The method for preparing functional recycled polyester-nylon composite microfiber according to claim 5, characterized in that, The preparation method of the bisoxazoline chain extender A in step 2 is as follows: under a nitrogen atmosphere, 2-isopropenyl-2-oxazoline and thiol-polyethylene glycol-thiol with a molecular weight of 200 are added into a reaction kettle at a molar ratio of 2.1:1, then 3-5 times the total mass of the reactants of DMF solvent and 0.5% of the total mass of the reactants of photoinitiator 500 are added, and the reaction is carried out under ultraviolet light with a wavelength of 365 nm for 12 hours; after the reaction is completed, the solvent is removed by a rotary evaporator at a temperature of 80°C and a vacuum degree of -0.09 MPa; then vacuum drying is carried out at a temperature of 80°C and a vacuum degree of -0.09 MPa for 6 hours to obtain the bisoxazoline chain extender A. The preparation method of the bisoxazoline chain extender B in step 5 is as follows: under a nitrogen atmosphere, 2-isopropenyl-2-oxazoline and thiol-polyethylene glycol-thiol with a molecular weight of 400 are added into a reaction kettle at a molar ratio of 2.1:1, then 3-5 times the total mass of the reactants of DMF solvent and 0.5% of the total mass of the reactants of photoinitiator 500 are added, and the reaction is carried out under ultraviolet light with a wavelength of 365 nm for 12 hours; after the reaction is completed, the solvent is removed by a rotary evaporator at a temperature of 80°C and a vacuum degree of -0.09 MPa; then vacuum drying is carried out at a temperature of 80°C and a vacuum degree of -0.09 MPa for 6 hours to obtain the bisoxazoline chain extender B.

7. The method for preparing functional recycled polyester-nylon composite microfiber according to claim 5, characterized in that, The temperature of each zone of the double screw extruder in step 6 is as follows: the first zone is 260-265°C, the second zone is 268-272°C, the third zone is 275-278°C, and the fourth zone is 278-280°C, and the screw rotation speed is 180 r / min. The temperature of each zone of the single screw extruder in step 5 is as follows: the feeding section is 258-260°C, the compression section is 265-268°C, and the metering section is 272-275°C, and the screw rotation speed is 140 r / min.

8. The method for preparing functional recycled polyester-nylon composite microfiber according to claim 5, characterized in that, The temperature of the spinning box in step 7 is 288-290°C for the polyester side and 278-280°C for the nylon side.

9. The method for preparing functional recycled polyester-nylon composite microfiber according to claim 5, characterized in that, ​ 10. The method for preparing functional recycled polyester-nylon composite microfiber according to claim 5, characterized in that, ​