Spinning process and spinning production line for directly spinning 30D high-elastic ultra-fine denier polyester fiber from silver-loaded melt injection granules

Abstract

The application discloses a kind of spinning processes and spinning production lines of injection silver-loaded masterbatch melt direct spinning 30D high-elastic ultrafine denier polyester fiber, process includes: silver-loaded masterbatch is sequentially dedusted, impurity removal and depth drying, obtains the pretreatment masterbatch with water content≤45PPM after constant temperature storage and low-speed stirring;Silver-loaded masterbatch melt is obtained by small screw injection device melting plasticization;With high-elastic polyester melt is imported into low-temperature dynamic mixer high shear homogenization mixing, and silver-loaded high-elastic polyester mixed melt is obtained;After being sequentially metered, gradient metal sand filtration, extrusion is obtained melt stream by 75mm plate diameter spinneret;Firstly, 60mm windless slow cooling is carried out, and then outer ring blowing precision temperature control cooling is carried out to obtain nascent yarn;After being oiled by low-friction oil nozzle, it is gathered by front and rear double network devices to obtain gathered yarn;After being compensated by elastic tension, it is wound into shape by low tension, and finished fiber is obtained;High proportion silver-loaded masterbatch homogenization dispersion can be realized, and problems such as silver particle agglomeration, melt hydrolytic degradation and the like are solved.

Description

Technical Field

[0001] This invention relates to the field of functional polyester fiber spinning technology, and discloses a spinning process and spinning production line for direct melting of 30D high-elasticity ultrafine denier polyester fiber using silver-loaded masterbatch injection. Background Technology

[0002] 30D high-elastic ultrafine denier polyester fiber, due to its fine monofilaments, soft touch, and excellent resilience, is a core raw material for high-end intimate apparel fabrics. Silver-modified products, which impart long-lasting antibacterial, anti-mite, and deodorizing functions to the fiber, represent a high-value-added development direction in the current functional fiber industry. These products utilize a melt-spinning process with online addition of silver-loaded masterbatch, eliminating the need for subsequent antibacterial finishing steps, leaving no chemical residues, and offering significant green and environmentally friendly advantages. Furthermore, the silver functional components are firmly bonded to the fiber body, providing wash resistance and long-lasting antibacterial properties, resulting in high market added value and representing the mainstream R&D direction for functional differentiated chemical fibers.

[0003] Currently, the industry commonly uses a direct spinning process that blends silver-loaded masterbatch with polyester melt to produce antibacterial polyester fibers. High elasticity is achieved through polyester matrix modification and the coordinated control of spinning tension, temperature, and cooling parameters. The masterbatch addition ratio for conventional silver-loaded antibacterial fibers is usually controlled at a low level, and these fibers are mostly of conventional fineness. However, the 30D high-elastic ultrafine denier specification has an extremely fine monofilament fineness. To ensure long-lasting antibacterial and bacteriostatic rates, the silver-loaded masterbatch addition ratio needs to be increased to over 4.0%. Furthermore, the rheological properties and molecular orientation of high-elastic polyester melt differ significantly from those of conventional polyester melt, making it difficult for traditional equipment and processes to match the production of this specification. These technical shortcomings constitute a major bottleneck for industrialization.

[0004] In order to ensure long-lasting antibacterial effect, the proportion of silver-loaded masterbatch is increased. However, the high proportion of masterbatch is prone to uneven dispersion in polyester melt, and the nano-silver particles agglomerate, resulting in silver spots on the fiber surface, local loss of antibacterial performance, and a significant decrease in antibacterial durability.

[0005] Silver-loaded masterbatch is highly hygroscopic, and traditional drying processes cannot reduce the moisture content of the masterbatch to a safe range. Residual moisture will accelerate the hydrolytic degradation of polyester melt under high-temperature spinning conditions, destroy the high-elastic polyester molecular chains and modified groups, resulting in a sharp drop in fiber elasticity recovery rate and unstable mechanical properties.

[0006] 30D ultrafine denier fiber monofilaments are fine, and the melt rheological properties of high-elastic polyester are different from those of conventional polyester. Traditional cooling, oiling, and winding processes can easily lead to uneven cooling of the filaments, tension fluctuations, uneven yarn count, and high filament breakage rate in the finished product.

[0007] Traditional single static mixing structures cannot achieve deep mixing of high proportion silver-loaded masterbatch and high-elastic polyester melt. The distribution of silver functional components and high-elasticity modified components is disordered, and the fibers simultaneously exhibit antibacterial fluctuations and local elasticity deviations. Furthermore, agglomerated silver particles cannot be effectively filtered, clogging the micropores of the spinning plate. Combined with the special viscosity characteristics of high-elastic polyester melt, this leads to a significant reduction in the service life of the spinning components, making it impossible for the production line to operate continuously.

[0008] In summary, conventional processes are limited by the amount of masterbatch added, equipment structure, and process parameters, and cannot simultaneously meet the three major production requirements of high silver loading, ultra-fine denier, and high elasticity and resilience. Summary of the Invention

[0009] The purpose of this invention is to provide a spinning process and spinning production line for direct spinning of 30D high-elasticity ultrafine denier polyester fiber from injection-molten silver-loaded masterbatch, which solves the problems of uneven dispersion of high-proportion silver-loaded masterbatch, easy hydrolysis and degradation of melt, poor adaptability of ultrafine denier high-elasticity spinning, and easy clogging of spinning components in existing production processes.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A spinning process for direct melt spinning of 30D high-elasticity ultrafine denier polyester fiber using injection-molten silver-loaded masterbatch includes:

[0012] The silver-loaded masterbatch is subjected to dust removal, impurity removal, and deep drying in sequence. Through constant temperature storage and low-speed stirring, a pretreated masterbatch with a moisture content of ≤45PPM is obtained. Dust removal and impurity removal remove fine powder and foreign impurities from the surface of the masterbatch to prevent impurities from entering the melt and causing spinning defects. Through deep drying combined with constant temperature storage and low-speed stirring, the moisture content of the masterbatch is strictly controlled to below 45PPM, which prevents residual moisture from causing hydrolysis and degradation of the polyester melt in the high-temperature spinning environment, and protects the integrity of the high-elastic polyester molecular chain and modified groups.

[0013] The pretreated masterbatch is melted and plasticized using a small screw injection device to obtain silver-loaded masterbatch melt. The dried masterbatch is melted and plasticized using a small screw injection device to achieve online continuous melting and quantitative delivery of the masterbatch. The plasticization process is mild and controllable, and the output silver-loaded masterbatch melt with stable viscosity is produced, avoiding the deactivation of silver ions caused by prolonged high-temperature residence of the masterbatch.

[0014] The high-elastic polyester melt and the silver-loaded masterbatch melt are passed into a low-temperature dynamic mixer and mixed by high-shear homogenization to obtain a mixed melt of silver-loaded high-elastic polyester. High-shear homogenization mixing in a low-temperature environment can achieve deep homogeneous dispersion of a high proportion of silver-loaded masterbatch melt and high-elastic polyester melt, which not only ensures that the nano-silver particles do not agglomerate, but also avoids the destruction of silver ion activity and high-elasticity modified groups by high temperature.

[0015] The mixed melt is sequentially metered and filtered through gradient metal sand, then extruded through a 75mm diameter spinneret to obtain a fine melt stream. Metering ensures a stable and quantitative melt delivery, while gradient metal sand filtration intercepts agglomerated silver particles and impurities in layers, reducing melt flow resistance and extending the service life of the spinning assembly while ensuring filtration accuracy. The 75mm diameter spinneret increases the melt distribution area, adapting to the extrusion requirements of ultra-fine denier melts, ensuring uniform extrusion of the melt stream and regular monofilament cross-sections.

[0016] The melt stream is first slowly cooled in a 60mm windless zone, and then precisely cooled by external ring blowing to obtain nascent filaments. Slow cooling in the windless zone can slow down the cooling rate, eliminate the melt extrusion expansion effect, and allow the high-elastic polyester macromolecular chains to slowly and orderly arrange themselves. Precise temperature control cooling by external ring blowing achieves gradient cooling and shaping of the filaments, avoiding brittle breakage and elasticity loss in ultra-fine denier filaments due to excessively rapid cooling, and stabilizing the high-elastic orientation structure of the fibers.

[0017] After the nascent filaments are oiled by a low-friction nozzle, they are bundled together by a front and rear double-network device to obtain bundled filaments. The low-friction nozzle ensures that the filaments are oiled evenly without damaging the filament surface and reduces the friction coefficient between filaments. The front and rear double-network device gradually gathers and disperses the filaments, improves the filament cohesion, lubrication and antistatic properties, and avoids damage to the filaments and the silver functional components on the fiber surface by high-pressure airflow.

[0018] After elastic tension compensation, the bundled filaments are wound under low tension to obtain 30D high-elastic ultrafine denier silver-loaded antibacterial polyester fiber. Elastic tension compensation corrects tension fluctuations in real time, and low-tension winding matches the stretching and rebound characteristics of high-elastic fibers to avoid irreversible elastic deformation of fibers caused by excessive tension, thus ensuring that the finished filament cake is well-formed and unwinds smoothly.

[0019] As a preferred embodiment, the silver-loaded masterbatch is subjected to dust removal by a centrifugal fan, impurity removal by a cyclone separator, and then high-pressure dehumidification drying for 21 hours. It is then stored at a constant temperature of 80±5℃ with low-speed stirring at 5~8 rpm to obtain pretreated masterbatch with a moisture content ≤45PPM. The centrifugal fan combined with the cyclone separator efficiently removes fine powder and impurities from the masterbatch surface, preventing particle breakage and the generation of new fine powder. The 21-hour high-pressure dehumidification drying, combined with constant-temperature storage at 80±5℃ and low-speed stirring at 5~8 rpm, ensures uniform heating and no agglomeration of the masterbatch, strictly controlling the moisture content to below 45PPM and preventing melt hydrolysis during subsequent spinning.

[0020] In a preferred embodiment, the pretreated masterbatch is subjected to gradient melting and plasticization using a small screw injection unit with four-zone temperature control. The temperatures in the four zones along the material conveying direction are sequentially 263~268℃, 260~265℃, 258~263℃, and 253~258℃, while the extrusion pressure is controlled at 43~53 bar, resulting in a uniformly plasticized silver-loaded masterbatch melt. The four-zone decreasing gradient temperature control achieves gradual heating and melting, matching the melting characteristics of the silver-loaded masterbatch and avoiding localized overheating that could lead to silver ion deactivation or polyester matrix degradation. This extrusion pressure range ensures sufficient plasticization of the masterbatch while maintaining stable melt viscosity.

[0021] In a preferred embodiment, the high-elastic polyester melt is first homogenized in a static mixer, and then passed together with the silver-loaded masterbatch melt into a low-temperature dynamic mixer. High-shear mixing is performed at 268±3℃ and 31~36 rpm. 4.2% silver-loaded masterbatch and 0.1% polyester compatibilizer are added by weight to obtain a homogeneously dispersed silver-loaded high-elastic polyester mixed melt. The static mixer first eliminates local viscosity differences in the matrix melt, completing the initial mixing of the two phases; the low-temperature dynamic mixing conditions of 268±3℃ and 31~36 rpm balance the mixing uniformity and the thermal stability of the functional components; the 4.2% silver-loaded masterbatch addition ratio ensures the finished fiber meets long-term antibacterial standards; and the 0.1% polyester compatibilizer improves the interfacial compatibility of the two phases and inhibits silver particle agglomeration.

[0022] As a preferred embodiment, agglomerated silver particles are intercepted through a multi-stage gradient metal abrasive filter layer and quantitatively extruded through a 75mm diameter spinneret at 276~280℃. The initial pressure of the module is controlled at 13.3~14.3MPa, resulting in a rheologically stable melt stream. The multi-stage gradient filtration with increasing mesh size can progressively intercept agglomerated silver particles and impurities, reducing pressure loss and alleviating spinneret micropore clogging while ensuring filtration accuracy. The spinneret temperature of 276~280℃ and the initial module pressure of 13.3~14.3MPa match the rheological characteristics of the highly elastic melt, ensuring quantitative and uniform extrusion of the melt stream.

[0023] As a preferred embodiment, the molten stream is first subjected to delayed cooling in a 60mm windless zone, and then subjected to gradient cooling and shaping via an external ring blowing device with a temperature gradient guide layer. The air pressure is controlled at 24Pa, the air temperature at 21℃, and the relative humidity at 64%, resulting in a well-oriented nascent filament. The 60mm windless zone is highly matched to the extrusion expansion pattern of 30D ultra-fine denier filaments, allowing the macromolecular chains to arrange themselves in an orderly manner under natural conditions. The temperature gradient guide layer guides the cooling air to form a temperature gradient distribution along the filament axis. Combined with precise ring blowing parameters of 24Pa, 21℃, and 64%, this achieves a gradient transition and solidification of the filament from high to low temperatures, ensuring consistent fiber orientation and stable high elasticity.

[0024] In a preferred embodiment, the nascent filaments are uniformly oiled through a low-friction oil nozzle with a 0.04mm aperture specifically for silver-loaded fibers. They are then bundled in two stages by a dual-network device before and after the GR1 guide disc, with the air pressure controlled at 0.05MPa for the front network and 0.07MPa for the rear network, resulting in a stable bundle of filaments. The 0.04mm micro-aperture oil nozzle enables precise micro-oiling, preventing excessive oil from adsorbing silver ions and weakening the antibacterial properties. The dual-network device before and after the GR1 guide disc gradually gathers and disperses the filaments with progressively increasing low-pressure airflow, ensuring both cohesion and preventing fuzzing caused by airflow impact.

[0025] In a preferred embodiment, the bundled filaments are matched to the tensile resilience characteristics using an elastic tension compensation device. After the tension is adjusted by a lifting guide plate, they are wound by a frequency conversion winding head with a constant tension of 16~18cN and a winding angle of 6.0°~7.0° to obtain well-formed 30D high-elastic ultrafine denier silver-loaded antibacterial polyester fibers. This tension and winding angle parameter matches the characteristics of high-elastic fibers, avoiding irreversible elastic deformation of the fibers, ensuring stable elastic recovery rate, and simultaneously ensuring good filament cake formation and smooth unwinding.

[0026] As a preferred embodiment, a high-elastic polyester melt with a viscosity of 0.645~0.655 dl / g and an original elastic recovery rate of ≥86% is used, combined with a polyester-based heat-resistant silver nano-masterbatch with an effective silver content of ≥3500 mg / kg and a particle size of <1 μm, to obtain a silver-loaded antibacterial high-elastic fiber with balanced and stable performance. The high-elastic polyester melt in this viscosity range provides the fiber with basic mechanical properties and high elasticity; the heat-resistant silver nano-masterbatch with high effective silver content and submicron particle size endows the fiber with long-lasting antibacterial function, and its temperature resistance matches the spinning temperature, making it less prone to silver particle agglomeration and precipitation.

[0027] On the other hand, the present invention provides an injection silver masterbatch melt direct spinning production line for performing the above process, wherein a silver masterbatch pretreatment system, an online low temperature mixing system, a 30D special spinning component, a precision temperature control ring blowing system, a special oiling network system and a low tension winding system are connected in series along the material flow direction.

[0028] The silver-loaded masterbatch pretreatment system removes dust, impurities, and deeply dries the input silver-loaded masterbatch, outputting pretreated masterbatch with a moisture content ≤45PPM. This system is used to control the moisture content of the masterbatch from the source, remove impurities and fine powder, and prevent melt hydrolysis and degradation.

[0029] The online low-temperature mixing system performs low-temperature, high-shear homogenization mixing of the input silver-loaded masterbatch melt and the high-elastic polyester melt, and outputs a mixed melt of silver-loaded high-elastic polyester. This is used to achieve uniform dispersion of a high proportion of masterbatch and matrix melt, and to avoid high-temperature damage to the silver ion activity and high-elasticity modified groups.

[0030] The 30D dedicated spinning assembly meteres, filters, and spins the input mixed melt, outputting a fine melt stream to intercept agglomerated silver particles, adapting to the extrusion characteristics of ultrafine denier melts and extending the assembly's service life.

[0031] The precise temperature control ring blowing system performs windless slow cooling and precise temperature control cooling of the input melt stream through external ring blowing, and outputs nascent filaments. It is used to precisely control the fiber cooling rate and molecular orientation to ensure high elasticity and monofilament uniformity.

[0032] The dedicated oiling network system applies low-friction oil to the input nascent filaments and bundles them together with the front and rear dual networks, outputting bundled filaments. This system achieves uniform oiling and low-pressure bundling of the filaments, improves filament cohesion and processing performance, and avoids the adsorption of silver ions by the oil.

[0033] The low-tension winding system performs elastic tension compensation and low-tension winding on the input bundled filaments, and outputs finished filament cakes to maintain stable low-tension winding, ensuring stable fiber elasticity and filament cake forming quality.

[0034] Compared with existing technologies, this invention uses a combination of pretreatment processes including dust removal, deep drying, constant temperature storage, and low-speed stirring to strictly control the moisture content of the silver-loaded masterbatch to within 45 PPM, thus preventing polyester hydrolysis and degradation during high-temperature spinning from the source. Combined with a small-screw gradient melt plasticization and low-temperature dynamic high-shear mixing process, the melt viscosity fluctuates little, the polyester molecular chain structure is intact, and the nano-silver particles are uniformly dispersed in the fiber matrix without agglomeration. The finished fiber has consistent antibacterial properties throughout, with no silver spots or local antibacterial differences. The initial antibacterial rate against Escherichia coli and Staphylococcus aureus is ≥99%, and the antibacterial rate remains ≥95% after 50 standard water washes.

[0035] By combining metering, gradient metal sand filtration, and extrusion with a 75mm diameter spinneret, agglomerated silver particles and impurities are intercepted in stages. While ensuring filtration accuracy, the melt flow resistance is reduced, effectively alleviating the problem of micropore clogging in the spinneret. The continuous use cycle of the spinning assembly can reach 10-12 days, reducing fuzz and breakage, and increasing the overall product yield to over 98.3%.

[0036] Employing a graded cooling method combining slow cooling in a 60mm windless zone with precise temperature control via external ring blowing, coupled with low-friction oil nozzles and a front and rear dual-network bundled process, ultra-fine denier filaments can achieve uniform treatment across the entire area. This effectively solves the problems of uneven filament cooling, uneven yarn evenness, and filament breakage. The finished fiber yarn evenness CV value is ≤1.0%, the number of filaments is ≤0.3 / 1000m, and the breaking strength is ≥2.32cN / dtex.

[0037] By employing elastic tension compensation and low-tension constant-tension winding, combined with low-temperature control throughout the entire process, the high-elasticity modified groups are fully preserved, the polyester macromolecules are arranged in a regular manner, and the elastic recovery rate of the finished fiber is ≥86%. This avoids irreversible elastic deformation of the fiber caused by excessive tension, resulting in regular yarn cake formation, smooth unwinding, and excellent adaptability to subsequent processing.

[0038] The melt spinning process, which uses online addition of silver-loaded masterbatch, eliminates the need for subsequent antibacterial finishing, significantly reducing wastewater discharge from dyeing and antibacterial agents. The production line can be modified from a traditional melt spinning unit, with low modification costs and a wide range of adjustable process parameters. It can adapt to customized production needs with different antibacterial grades and elasticity indicators, making it suitable for large-scale mass production. Attached Figure Description

[0039] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0040] Figure 1 This is a process flow diagram of the equipment for online injection of silver-loaded masterbatch melt direct spinning of 30D high-elasticity ultrafine denier polyester fiber according to the present invention;

[0041] Figure 2 This is a schematic diagram of the production line structure of the present invention;

[0042] Figure 3 This is a schematic diagram of the overall process flow of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] A spinning process for direct melt spinning of 30D high-elasticity ultrafine denier polyester fiber using injection-molten silver-loaded masterbatch, such as... Figure 1 , 3 As shown, the specific implementation process is as follows:

[0046] S101: Dust removal, impurity removal, and deep drying of silver-loaded masterbatch

[0047] The silver-loaded masterbatch was subjected to dust removal, impurity removal and deep drying in sequence. After constant temperature storage and low-speed stirring, a pretreated masterbatch with a moisture content of ≤45PPM was obtained.

[0048] This embodiment employs a centrifugal fan in conjunction with a cyclone separator to perform wind-powered dust and impurity removal on the silver-loaded masterbatch. This removes fine powder, agglomerated particles, and foreign impurities adhering to the masterbatch surface, preventing impurities from entering the subsequent melt preparation stage and causing spinning defects. The dust- and impurity-removed masterbatch is then fed into a constant-temperature silo and subjected to deep dehumidification and drying using a high-pressure dehumidifier system for 21 hours. It is then stored at a constant temperature of 80±5℃. During storage, a low-speed stirring shaft within the silo operates at 5-8 rpm to prevent the masterbatch from agglomerating due to heat and to ensure uniform heating of the entire masterbatch. Testing revealed that the moisture content of the dried masterbatch is ≤45 PPM, meeting the low moisture content requirements for subsequent spinning.

[0049] S102: Pretreatment masterbatch melt plasticization

[0050] The pretreated masterbatch is melted and plasticized using a small screw injection device to obtain a silver-loaded masterbatch melt.

[0051] The dried pretreated masterbatch is fed into a small screw injection unit dedicated to silver-loaded masterbatch. Gradient melting and plasticization are achieved through a four-zone temperature control structure along the material conveying direction. The temperatures of the four zones are 263~268℃, 260~265℃, 258~263℃, and 253~258℃ respectively. The extrusion pressure is controlled at 43~53 bar to ensure that the masterbatch is fully plasticized while maintaining stable melt viscosity and avoiding local overheating that could lead to silver ion deactivation. Finally, a uniformly plasticized silver-loaded masterbatch melt is obtained and conveyed to the subsequent mixing process through a constant temperature feeding channel.

[0052] S103: Low-temperature high-shear homogeneous mixing of melt

[0053] The high-elastic polyester melt and the silver-loaded masterbatch melt are fed into a low-temperature dynamic mixer and mixed by high-shear homogenization to obtain a mixed melt of silver-loaded high-elastic polyester.

[0054] The high-elastic polyester melt is produced by polymerizing PTA and EG raw materials and high-elasticity modifier in a one-head-two-tail polymerization device. After being transported by the high-elastic polyester melt conveying pipeline and the melt conveying booster pump, the polyester compatibilizer is added at the polyester compatibilizer addition port. The melt is first homogenized in a high-elastic melt static mixer to eliminate local viscosity differences in the matrix melt. Then, it is passed together with the silver-loaded masterbatch melt into a low-temperature dynamic mixer. Under the temperature control condition of 268±3℃, high-shear dynamic mixing is carried out at a speed of 31~36rpm. 4.2% silver-loaded masterbatch and 0.1% polyester compatibilizer are added by mass. Through gentle and sufficient high-shear action, the nano-silver particles are uniformly dispersed in the high-elastic polyester matrix, and finally, a non-agglomerated and uniformly composed silver-loaded high-elastic polyester mixed melt is obtained.

[0055] S104: Mixed melt metering, gradient filtration and spinneret extrusion

[0056] The mixed melt is sequentially metered, filtered through gradient metal sand, and extruded through a 75mm diameter spinneret to obtain a fine melt stream.

[0057] After being distributed by the melt distribution valve, the mixed melt enters the spinning box and is metered and quantitatively delivered to the 30D high-elasticity ultra-fine denier special spinning assembly by the spinning metering pump. It first flows through a gradient metal sand filter layer, and the filtration accuracy increases step by step along the melt flow direction, intercepting agglomerated silver particles and impurities in the melt in layers to avoid clogging of the spinneret micropores. The initial pressure of the spinning assembly is controlled at 13.3~14.3MPa. The filtered melt is quantitatively extruded through a special spinneret with a plate diameter of 75mm at 276~280℃ to form a melt stream with a uniform cross section.

[0058] S105: Melt stream staged cooling and shaping

[0059] The melt stream is first slowly cooled in a 60mm windless zone, and then precisely cooled by external ring blowing to obtain the nascent filament.

[0060] The molten filaments extruded from a specialized spinneret first enter a 60mm high, windless slow-cooling section. In this windless environment, they are naturally and slowly cooled, slowing the cooling rate and eliminating the melt extrusion swelling effect. This allows the high-elastic polyester macromolecular chains to slowly and regularly align, stabilizing the fiber's orientation structure. The slowly cooled filaments then enter a TMT external ring-blown precision temperature-controlled cooling device. The device's inner wall is equipped with a temperature gradient guide layer. Through a soft air outlet structure, cooling air at a pressure of 24Pa, a temperature of 21℃, and a relative humidity of 64% is used for gradient cooling and shaping, allowing the filaments to transition and solidify from a high-temperature to a low-temperature gradient, resulting in well-oriented, evenly shaped nascent filaments.

[0061] S106: Oiling of nascent filaments and double-network bundling

[0062] After the nascent filaments are oiled through a low-friction nozzle, they are bundled together by a front and rear dual-network device to obtain bundled filaments.

[0063] The nascent filaments flow downwards to a low-friction oil nozzle specifically designed for silver-loaded fibers for uniform oiling. The nozzle has a 0.04mm orifice diameter, enabling precise micro-oiling, reducing the friction coefficient between filaments, improving the smoothness of subsequent processing, and preventing the oil from adsorbing silver ions that could affect the antibacterial effect. After oiling, the filaments undergo two-stage bundling via a dual-network device positioned before and after the GR1 guide disc. The air pressure of the front dual-network device is controlled at 0.05MPa, while the air pressure of the rear dual-network device is controlled at 0.07MPa. This progressively increasing low-pressure airflow gradually gathers the dispersed filaments, improving overall filament cohesion and preventing issues such as filament drift and spiderweb-like structures, ultimately resulting in a stable and cohesive bundled filament.

[0064] S107: Elastic tension compensation and low-tension winding of bundled filaments

[0065] After elastic tension compensation, the bundled filaments are wound into shape under low tension to obtain 30D high-elastic ultrafine denier silver-loaded antibacterial polyester fiber.

[0066] After the bundled filaments are adjusted in direction and tension by the lifting guide plate tension adjustment unit, the tension fluctuations are corrected in real time by the elastic tension compensation device to match the tensile and rebound characteristics of the high-elasticity fiber. The bundled filaments are then fed into a frequency-controlled low-tension winding head. During production, the winding tension is controlled at 16~18cN and the winding angle at 6.0°~7.0°, maintaining constant tension throughout the winding process to avoid irreversible elastic deformation of the fiber caused by tension fluctuations and ensure the stability of the fiber's high elasticity. After winding, a well-formed finished filament cake is obtained. After being wound by the finished filament cake winding unit, it is sealed and packaged to obtain 30D high-elasticity ultrafine denier silver-loaded antibacterial polyester fiber.

[0067] Example 2

[0068] This embodiment, within the process framework of Embodiment 1, selects a set of specific preferred parameters for mass production verification. The specific parameters are as follows:

[0069] Masterbatch pretreatment: The masterbatch is dusted by a centrifugal fan, impurities are removed by a cyclone separator, and it is then dehumidified and dried under high pressure for 21 hours. The material is kept at a constant temperature of 80℃ in the silo and stirred at a low speed of 6 rpm. The final moisture content of the masterbatch is 42 PPM.

[0070] Melt plasticizing: The temperatures of the four zones of the small screw injection unit are 265℃, 262℃, 260℃ and 255℃ respectively, and the extrusion pressure is 48 bar;

[0071] Melt mixing: The high-elastic polyester melt is first homogenized by a static mixer, with silver masterbatch added at a mass ratio of 4.2% and polyester compatibilizer added at a mass ratio of 0.1%. The dynamic mixing temperature is 268℃ and the rotation speed is 33rpm.

[0072] Filtration and extrusion: Multi-stage gradient metal sand filtration is adopted, with an initial component pressure of 13.8MPa, a spinneret diameter of 75mm, a spinneret temperature of 278℃, and a spinning box temperature of 273℃.

[0073] Staged cooling: No-wind zone height 60mm, annular air pressure 24Pa, air temperature 21℃, relative humidity 64%;

[0074] Oiling cluster: oil nozzle orifice diameter 0.04mm, front network air pressure 0.05MPa, rear network air pressure 0.07MPa;

[0075] Winding and forming: winding tension 17cN, winding angle 6.5°, constant tension winding is maintained by elastic tension compensation device.

[0076] Through continuous production testing, the finished fiber prepared in this embodiment exhibits stable performance indicators: breaking strength ≥2.32 cN / dtex, coefficient of variation of breaking strength ≤3.5%, elongation at break M1±3.5%, coefficient of variation of elongation at break ≤3.6%, evenness CV value ≤1.0%, filament count ≤0.3 / 1000m, boiling water shrinkage ≤3.0%, oil content M2±0.04%, elastic recovery rate ≥86%, initial antibacterial rate against Escherichia coli and Staphylococcus aureus ≥99%, and antibacterial rate after 50 washes ≥95%; the spinning assembly has a continuous service life of 10-12 days, the overall product yield is ≥98.3%, the spinning process is stable, and the incidence of filament breakage and end breakage is low, enabling continuous and stable production. This verifies the reliability and practicality of the process parameter range.

[0077] Example 3

[0078] This embodiment, within the process framework of Embodiment 1, selects the lower limit of the process parameter range for production verification. The specific parameters are as follows:

[0079] Masterbatch pretreatment: hopper constant temperature 75℃, low-speed stirring speed 5rpm, drying for 21h, masterbatch moisture content 45PPM; Melting and plasticizing: four zone temperatures are 263℃, 260℃, 258℃, and 253℃ respectively, extrusion pressure 43bar; Melt mixing: dynamic mixing temperature 265℃, speed 31rpm, silver-loaded masterbatch added 4.2%, compatibilizer added 0.1%; Filtering and extrusion: component initial pressure 13.3MPa, spinneret temperature 276℃; Staged cooling: windless zone 60mm, air pressure 24Pa, air temperature 21℃, relative humidity 64%; Oiling and bundling: oil nozzle orifice diameter 0.04mm, front network air pressure 0.05MPa, rear network air pressure 0.07MPa; Winding and forming: winding tension 16cN, winding angle 6.0°.

[0080] Testing revealed that the finished fiber prepared in this embodiment had a breaking strength of 2.32 cN / dtex, a yarn evenness CV value of 1.0%, an elastic recovery rate of 86%, an initial antibacterial rate of 99%, an antibacterial rate of 95% after 50 washes, a continuous use period of 10 days for the spinning assembly, and a comprehensive product yield of 98.3%. All indicators met the product quality requirements, verifying the feasibility of the lower limit values ​​of the process parameters.

[0081] Example 4

[0082] refer to Figure 1 In this embodiment, within the process framework of Embodiment 1, the upper limit of the process parameter range is selected for production verification. The specific parameters are as follows:

[0083] Masterbatch pretreatment: constant temperature of 85℃ in the silo, low-speed stirring speed of 8 rpm, drying for 21 hours, masterbatch moisture content of 40 PPM; melt plasticizing: the four zone temperatures are 268℃, 265℃, 263℃, and 258℃ respectively, and the extrusion pressure is 53 bar; melt mixing: dynamic mixing temperature of 271℃, speed of 36 rpm, silver-loaded masterbatch added 4.2%, compatibilizer added 0.1%; filter extrusion: initial component pressure of 14.3 MPa, spinneret temperature of 280℃; staged cooling: 60 mm windless zone, air pressure of 24 Pa, air temperature of 21℃, relative humidity of 64%; oiling and bundling: oil nozzle diameter of 0.04 mm, front network air pressure of 0.05 MPa, and rear network air pressure of 0.07 MPa; winding and forming: winding tension of 18 cN, winding angle of 7.0°.

[0084] Testing revealed that the finished fiber prepared in this embodiment exhibited a breaking strength of 2.36 cN / dtex, a yarn evenness CV value of 0.9%, an elastic recovery rate of 87%, an initial antibacterial rate of 99.3%, an antibacterial rate of 95.6% after 50 washes, a continuous use period of 12 days for the spinning assembly, and a comprehensive product yield of 98.6%. All indicators met the product quality requirements and showed slight improvements, verifying the feasibility of the upper limit of the process parameters. Examples 3 and 4, together with Example 2, support the complete feasibility of the process parameter range claimed in the claims.

[0085] Example 5

[0086] This embodiment describes a melt-spinning production line for injection-loaded silver masterbatch to achieve the above-mentioned spinning process, such as... Figure 2 As shown, the silver-loaded masterbatch pretreatment system, online low-temperature mixing system, 30D special spinning assembly, precision temperature control ring blowing system, special oiling network system, and low-tension winding system are connected in series along the material flow direction. The specific structure and function of each system are as follows:

[0087] Silver-loaded masterbatch pretreatment system: This system removes dust, impurities, and deeply dries the input silver-loaded masterbatch, outputting pretreated masterbatch with a moisture content ≤45PPM. The system mainly consists of a centrifugal fan, cyclone separator, high-pressure dehumidifier system, heater, constant-temperature silo, and low-speed stirring shaft. It can perform wind-driven dust removal, cyclone impurity removal, deep dehumidification and drying, and constant-temperature anti-caking storage of the silver-loaded masterbatch, strictly controlling the masterbatch moisture content to below 45PPM, thus preventing silver particle agglomeration and melt hydrolysis degradation from the source.

[0088] Online Cryogenic Mixing System: The online cryogenic mixing system performs low-temperature, high-shear homogenization mixing of the input silver-loaded masterbatch melt and high-elastic polyester melt, outputting a mixed melt of silver-loaded high-elastic polyester. This system employs a combination of a dedicated small-screw injection device for silver-loaded masterbatch, a constant-temperature feeding channel, a static mixer for high-elastic melt, and a low-temperature dynamic mixer. The high-elastic polyester melt is transported from a one-end-two-end polymerization device via a high-elastic polyester melt conveying pipeline, a melt conveying booster pump, and a polyester compatibilizer addition port. After adding compatibilizer, it undergoes preliminary homogenization in the static mixer, and then completes high-shear homogenization mixing with the silver-loaded masterbatch melt, which is melted by the small-screw injection device and conveyed by the constant-temperature feeding channel, in the low-temperature dynamic mixer. This achieves a high proportion of homogeneous dispersion of the silver-loaded masterbatch and high-elastic polyester melt, while simultaneously completing the mixing under low-temperature conditions, protecting the silver ion activity and high-elasticity modified groups from damage.

[0089] 30D Dedicated Spinning Component: The 30D dedicated spinning component meteres, filters, and spins the input mixed melt, outputting a fine melt stream. This component is housed within the spinning chamber, with a spinning metering pump at the front end. Inside, it features a gradient metal sand filter layer and a dedicated spinneret with a 75mm diameter. This allows for the layered interception of agglomerated silver particles and impurities while adapting to the extrusion requirements of ultra-fine denier melts, ensuring uniform extrusion of the melt stream and extending the component's service life.

[0090] Precision Temperature Controlled Circular Blowing System: This system performs slow cooling in a windless zone followed by precise temperature control through external circular blowing on the input melt stream, outputting nascent filaments. The system consists of a 60mm windless slow cooling section, a TMT (Technology, Technology, and Mechanism) external circular blowing precise temperature control cooling device, a temperature gradient guide layer, and a soft air outlet structure. By employing a combination of slow cooling followed by gradient circular blowing, it precisely controls the fiber cooling rate and molecular orientation, eliminating extrusion swelling effects and ensuring stable monofilament uniformity and high elasticity.

[0091] Dedicated oiling network system: The dedicated oiling network system applies low-friction oil to the input nascent filaments and performs front and rear dual-network bundling, outputting bundled filaments. This unit includes a dedicated low-friction oil nozzle for silver-loaded fibers and front and rear dual-network devices arranged before and after the GR1 guide disc. It can achieve uniform micro-oiling and gradual low-pressure bundling of the filaments, improving filament cohesion and preventing damage to the surface of individual filaments and the adsorption of silver ions by the oil.

[0092] Low-tension winding system: The low-tension winding system performs elastic tension compensation and low-tension winding on the input bundled filaments, outputting a finished filament cake. This unit is equipped with a lifting guide plate tension adjustment unit, an elastic tension compensation device, and a frequency conversion low-tension winding head. Downstream, it connects to the finished filament cake winding unit and the sealed packaging station, which can maintain stable low-tension winding throughout the process, avoiding irreversible elastic deformation of the fibers and ensuring stable high elasticity of the finished product and high filament cake forming quality.

[0093] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A spinning process for direct melting of silver-loaded masterbatch into 30D high-elasticity ultrafine denier polyester fiber, characterized in that, include: The silver-loaded masterbatch was subjected to dust removal, impurity removal and deep drying in sequence. After constant temperature storage and low-speed stirring, a pretreated masterbatch with a moisture content of ≤45PPM was obtained. The pretreated masterbatch is melted and plasticized using a small screw injection device to obtain a silver-loaded masterbatch melt; The high-elastic polyester melt and the silver-loaded masterbatch melt are fed into a low-temperature dynamic mixer and mixed by high-shear homogenization to obtain a mixed melt of silver-loaded high-elastic polyester. The mixed melt is sequentially metered, filtered through gradient metal sand, and extruded through a 75mm diameter spinneret to obtain a fine melt stream; The melt stream is first slowly cooled in a 60mm windless zone, and then precisely cooled by external ring blowing to obtain the nascent filament. After the nascent filaments are oiled through a low-friction nozzle, they are bundled together by a front and rear dual-network device to obtain bundled filaments. After elastic tension compensation, the bundled filaments are wound into shape under low tension to obtain 30D high-elastic ultrafine denier silver-loaded antibacterial polyester fiber.

2. The spinning process for direct melt spinning of 30D high-elasticity ultrafine denier polyester fiber from injection-molten silver-loaded masterbatch according to claim 1, characterized in that, The silver-loaded masterbatch was subjected to dust removal by a centrifugal fan, impurity removal by a cyclone separator, and then high-pressure dehumidification drying for 21 hours. It was then stored at a constant temperature of 80±5℃ with low-speed stirring at 5~8 rpm to obtain a pretreated masterbatch with a moisture content ≤45PPM.

3. The spinning process for direct melt spinning of 30D high-elasticity ultrafine denier polyester fiber from injection-loaded silver masterbatch according to claim 1, characterized in that, The pretreated masterbatch is subjected to gradient melting and plasticization using a small screw injection device with four temperature control zones. The temperatures of the four zones along the material conveying direction are 263~268℃, 260~265℃, 258~263℃, and 253~258℃ respectively. The extrusion pressure is controlled at 43~53 bar to obtain a uniformly plasticized silver-loaded masterbatch melt.

4. The spinning process for direct melt spinning of 30D high-elasticity ultrafine denier polyester fiber from injection-molten silver-loaded masterbatch according to claim 1, characterized in that, The high-elastic polyester melt is first homogenized in a static mixer, and then passed together with the silver-loaded masterbatch melt into a low-temperature dynamic mixer. The mixture is then mixed under high shear at 268±3℃ and 31~36 rpm. 4.2% silver-loaded masterbatch and 0.1% polyester compatibilizer are added by weight to obtain a uniformly dispersed silver-loaded high-elastic polyester mixed melt.

5. The spinning process for direct melt spinning of 30D high-elasticity ultrafine denier polyester fiber from injection-molten silver-loaded masterbatch according to claim 1, characterized in that, Agglomerated silver particles are intercepted by a multi-stage gradient metal sand filter layer and quantitatively extruded through a 75mm diameter spinneret at 276~280℃. The initial pressure of the component is controlled at 13.3~14.3MPa to obtain a rheologically stable melt stream.

6. The spinning process for direct melt spinning of 30D high-elasticity ultrafine denier polyester fiber from injection-molten silver-loaded masterbatch according to claim 1, characterized in that, The melt stream is first cooled slowly in a 60mm windless zone, and then cooled and shaped by an outer ring blowing device with a temperature gradient guide layer. The air pressure is controlled at 24Pa, the air temperature at 21℃, and the relative humidity at 64%, resulting in a well-oriented nascent filament.

7. The spinning process for direct melt spinning of 30D high-elasticity ultrafine denier polyester fiber from injection-molten silver-loaded masterbatch according to claim 1, characterized in that, The nascent filaments are uniformly oiled through a low-friction oil nozzle with a 0.04mm aperture for silver-loaded fibers, and then bundled in two stages by a dual-network device before and after the GR1 guide disc. The air pressure of the front network is controlled at 0.05MPa and the air pressure of the rear network is controlled at 0.07MPa to obtain a stable bundled filament.

8. The spinning process for direct melt spinning of 30D high-elasticity ultrafine denier polyester fiber from injection-molten silver-loaded masterbatch according to claim 1, characterized in that, The bundled filaments are matched with the tensile rebound characteristics by an elastic tension compensation device. After the tension is adjusted by a lifting guide plate, they are wound by a frequency conversion winding head with a constant tension of 16~18cN and a winding angle of 6.0°~7.0° to obtain well-formed 30D high-elastic ultrafine denier silver-loaded antibacterial polyester fiber.

9. The spinning process for direct melt spinning of 30D high-elasticity ultrafine denier polyester fiber from injection-molten silver-loaded masterbatch according to claim 1, characterized in that, By using a high-elastic polyester melt with a viscosity of 0.645~0.655dl / g and an original elastic recovery rate of ≥86%, and combining it with a polyester-based heat-resistant nano-silver masterbatch with an effective silver content of ≥3500mg / kg and a particle size of <1μm, a silver-loaded antibacterial high-elastic fiber with balanced and stable performance is obtained.

10. A melt-spinning production line for injecting silver-loaded masterbatch for performing the process described in any one of claims 1 to 9, characterized in that, Along the material flow direction, a silver-loaded masterbatch pretreatment system, an online low-temperature mixing system, a 30D dedicated spinning assembly, a precise temperature control ring blowing system, a dedicated oiling network system, and a low-tension winding system are connected in series to obtain a 30D high-elastic ultra-fine denier silver-loaded polyester fiber spinning production line that can continuously and stably produce in large quantities.

Images