Negative ion colored yarn nylon 6 fiber and preparation method thereof

Abstract

The application discloses a kind of negative ion color yarn chinlon 6 fibers and preparation method thereof, belong to synthetic fiber technical field.The application is respectively to the surface modification of silane coupling agent to negative ion master batch, to the modification of uniform dyeing accelerator and dispersant compound to color master batch;After the raw material of skin, core layer is fused by double screw, it is formed by concentric circle skin-core spinneret extrusion, then by cooling, oiling, drafting and winding to obtain finished product.The application separates coloring and negative ion function by skin-core structure design, and cooperates master batch modification and spinning process optimization, simultaneously solves the technical problems of uneven dyeing, poor color fastness and unstable negative ion function of chinlon 6 fiber, and the obtained fiber color fastness reaches more than 4 levels, negative ion release is durable, and mechanical property is excellent.

Description

Technical Field

[0001] This invention belongs to the field of synthetic fiber technology, specifically relating to a negative ion colored yarn nylon 6 fiber and its preparation method. Background Technology

[0002] Nylon 6 fiber, due to its excellent mechanical properties, abrasion resistance, and elastic recovery, is widely used in textiles, apparel, home textiles, and industrial materials. With the upgrading of consumption and the popularization of health concepts, the market's requirements for textile materials have shifted from basic performance to a composite, high-quality direction that combines health functionality with visual appeal. Among these, the negative ion function, which can purify the air, inhibit bacteria, and improve human comfort by releasing negative ions, has become an important development direction for functional nylon fibers; while uniform, bright, and durable color is key to determining the fiber's aesthetic value and product competitiveness.

[0003] In existing technologies, from the perspective of material compatibility and dispersibility, there are often significant polarity differences and interfacial incompatibility issues between the powder materials introduced to achieve negative ion function and the nylon 6 matrix. Agglomeration easily occurs during melt blending and spinning, leading to uneven internal fiber structure. This structural inhomogeneity directly affects the dye uptake rate and distribution uniformity during subsequent dyeing. Secondly, from the perspective of fiber dyeing characteristics, nylon 6 is a hydrophobic fiber, and its dyeing process generally presents an inherent contradiction of excessively fast dye uptake rate and poor evenness. This contradiction is particularly pronounced when using traditional post-dyeing processes. While solution dyeing can avoid post-dyeing, the dispersion stability of the masterbatch in the matrix and the negative impact of high pigment content on fiber mechanical properties remain challenging problems requiring precise control. Furthermore, whether using post-dyeing or solution dyeing, simultaneously ensuring excellent color fastness while maintaining a high dye uptake rate remains a pain point in the industry.

[0004] Currently, existing technologies employ core-sheath composite spinning techniques for improvement. These solutions, through the isolation effect of the core-sheath structure, alleviate the mutual interference between different functional components to some extent. However, these existing solutions mostly focus on improving a single performance dimension, such as addressing issues related to color expressiveness, fastness, or cost. However, when faced with the need to simultaneously integrate high-efficiency negative ion release with high-uniformity, high-fastness coloring technology, potential mutual adsorption and interference between functional powders and colorants, the potential impact of the sheath coloring system on the functional stability of the core layer, and the difficulty in maintaining excellent mechanical properties and spinnability of fibers in complex multiphase systems, these deep-seated contradictions demonstrate that existing technologies cannot simultaneously achieve stable and long-lasting negative ion release and superior dyeing performance in a single fiber. This results in products with limited functionality or insufficient overall quality, failing to meet the market's growing demand for multifunctional, high-quality nylon fibers.

[0005] The patent with publication number CN117626473A, entitled "A method for preparing polyamide 6 with a core-sheath composite solution dyeing", specifically discloses that color masterbatches of different colors are mixed with polyamide 6 chips as the sheath and core components, and colored fibers are prepared by core-sheath composite spinning technology to achieve rapid color matching and improve color fastness. However, the above technical solution only focuses on solving the problems of fiber coloring and spinnability. Its technical approach is still limited to the scope of color expression and has not yet addressed how to stably introduce and maintain health functions such as negative ion release in this structure. It is difficult to solve the common industry problem of uneven dyeing, decreased color fastness and functional degradation caused by the mutual interference between functional additives and the coloring system. Summary of the Invention

[0006] To address the shortcomings of traditional core-sheath structures in existing technologies, which struggle to simultaneously achieve functional stability and high-quality color, this invention provides a negative ion colored yarn nylon 6 fiber and its preparation method. By designing a specific core-sheath composite structure, modifying the interface of the negative ion masterbatch and the color masterbatch respectively, and optimizing the spinning process parameters, a core-sheath composite fiber with stable negative ion release function, high color fastness, uniform dyeing effect, and excellent mechanical properties is achieved.

[0007] To achieve this objective, the following solution is provided: This invention provides a negative ion colored yarn nylon 6 fiber, which adopts a core-sheath composite structure, including a sheath layer and a core layer; wherein, the sheath layer is a modified matrix of modified color masterbatch and nylon 6 chips; the core layer is a modified matrix of modified negative ion masterbatch and nylon 6 chips; the mass ratio of the sheath layer to the core layer is 3:7~5:5.

[0008] Furthermore, the modified color masterbatch is prepared by mixing and treating the color masterbatch with a polyurethane-type polymeric dispersant and a leveling accelerator; wherein the amount of polyurethane-type polymeric dispersant is 5-10% of the mass of the color masterbatch, and the particle size of the color masterbatch is 200-400 nm.

[0009] Furthermore, the modified negative ion masterbatch is obtained by modifying the negative ion masterbatch with silane coupling agent KH-550; wherein, the amount of silane coupling agent KH-550 added is 1~3% of the mass of the negative ion masterbatch; the negative ion masterbatch contains tourmaline composite powder with a particle size of 300~500 nm.

[0010] Furthermore, the added mass of modified negative ion masterbatch in the core layer is 5-14.3% of the total mass of the core layer; the added mass of modified color masterbatch in the skin layer is 8-25% of the total mass of the skin layer.

[0011] This invention also provides a method for preparing negative ion colored nylon 6 fiber, comprising the following steps: S1. Mix nylon 6 chips and modified color masterbatch evenly to obtain the skin layer compound material; mix nylon 6 chips and modified negative ion masterbatch evenly to obtain the core layer compound material. S2. The core layer compound raw material and the skin layer compound raw material are respectively melt-extruded through a twin-screw extruder to obtain a melt; S3. The melt is transported to the spinning box by a metering pump and extruded through the concentric core-sheath spinneret in the composite spinning assembly to form primary fibers with a core-sheath composite structure. S4. The initial fibers are cooled by side blowing through the side blowing window, then bundled and oiled at the bundling point, stretched and shaped, networked and wound to obtain negative ion colored yarn nylon 6 fiber.

[0012] Furthermore, in step S1, a leveling accelerator is added to the leather blending raw materials, and the amount of leveling accelerator added is 0.5~3% of the total mass of the leather.

[0013] Furthermore, in step S2, the temperature control of each zone of the twin-screw extruder is as follows: Zone 1 253~262℃, Zone 2 254~268℃, Zone 3 255~268℃, Zone 4 256~268℃, and Zone 5 257~268℃.

[0014] Furthermore, in step S3, the composite spinning assembly contains a filter assembly, which adopts a double-layer nonwoven filter structure, with the upper filter having a size of 77×6×20 μm and the lower filter having a size of 50×4×15 μm.

[0015] Further, in step S4, the side-blowing air temperature is 20~25℃ and the air speed is 0.4~0.5 m / s; the oil used for bundling is FDY oil with a concentration of 6%~8%; the stretching and shaping includes sequentially using cold rollers and hot rollers for stretching, wherein the temperature of the hot rollers is 150~170℃ and the stretching ratio is 1.1~1.5; the winding speed is 4200~4800 m / min and the initial value of the winding forming angle is 5.0~6.0.

[0016] Furthermore, the distance between the clustering point and the spinneret is 1000~1300 mm; the distance between the clustering point and the side blowing window is 150~250 mm.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention achieves physical isolation between functional and coloring components by constructing a specific core-to-skin ratio for the negative ion functional layer and the coloring skin layer. This fundamentally avoids direct contact and mutual adsorption between the negative ion powder and the color pigment molecules, effectively solving the problem of functional attenuation and dyeing defects caused by component interference in traditional blending processes. The core layer focuses on carrying and stably releasing negative ions, while the skin layer focuses on presenting and stabilizing the color; each performs its specific function and works synergistically.

[0018] 2. This invention employs the silane coupling agent KH-550 to modify the surface of the masterbatch containing tourmaline composite powder, forming an organic coating layer on its surface. This significantly enhances the interfacial compatibility between the powder and the nylon 6 matrix, greatly reducing agglomeration caused by polarity differences, and enabling the negative ion powder to achieve uniform nanoscale dispersion in the core layer. Furthermore, the modified powder surface active groups can form a stronger bond with the nylon 6 macromolecules, improving the density and integrity of the core layer structure and providing a more stable supporting substrate for the skin layer.

[0019] 3. This invention modifies the color masterbatch by blending it with a polyurethane-type polymeric dispersant and a leveling accelerator. The polymeric dispersant ensures the long-term dispersion stability of the pigment in the fiber matrix and prevents secondary aggregation of pigments during processing and use. The introduction of the leveling accelerator directly addresses the pain points of fast dyeing rate and poor leveling of nylon 6, significantly improving the uniform distribution of dye molecules in the fiber matrix and suppressing the generation of color spots and color differences from the source.

[0020] 4. The graded filtration system with a double-layer nonwoven fabric filter structure effectively intercepts impurities and agglomerates of different sizes, ensuring extremely high cleanliness of the melt entering the spinneret and eliminating spinneret blockage, fiber diameter fluctuations, or core-sheath interface defects caused by impure melt. Furthermore, by controlling the spatial position of the bundling points, it ensures that the nascent fibers undergo sufficient and uniform cooling and solidification after leaving the spinneret, and are bundled and oiled at the optimal time when internal stress is moderately relaxed and temperature distribution tends to stabilize. Therefore, this invention, through the synergistic optimization of spinning process parameters, including temperature control matching the melting characteristics of the modified masterbatch, graded filtration ensuring melt cleanliness, cooling and bundling conditions ensuring uniform fiber solidification, and post-drawing processing to strengthen the core-sheath structure and mechanical properties, collectively constitutes a stable and efficient preparation system. This process system, while ensuring high spinnability, firmly locks the functional and color components of the fiber within the optimized core-sheath structure, thus providing a reliable manufacturing guarantee for achieving high product performance.

[0021] 5. This invention solves the bottleneck of nylon 6 fiber's inability to simultaneously achieve both functionality and color through the systematic synergy of material modification, structural design, and process parameters. The prepared fiber, within the framework of a core-sheath structure, simultaneously achieves stable negative ion release and excellent coloring performance, with a color fastness of grade 4 or higher, while fully maintaining the core mechanical properties of nylon 6 fiber (breaking strength ≥ 4.5 cN / dtex, elongation at break 35~45%), providing a reliable solution for the industrialization of multifunctional, high-quality nylon 6 fiber. Detailed Implementation

[0022] The present invention will be further described below with reference to preferred embodiments. The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values. These ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed herein.

[0023] Unless otherwise specified, the experimental methods in the following embodiments are conventional methods, performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0024] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0025] Example 1 This embodiment provides a method for preparing negative ion colored nylon 6 fiber, including the following steps: S1. Take 2.0 kg of bright silver-gray masterbatch with a particle size of 200~400 nm and add it to a high-speed mixer. At the same time, add 100 g of polyurethane-type polymeric dispersant and 100 g of leveling accelerator. Stir at 165℃ and 400 rpm for 3.2 h, and then dry to a moisture content ≤0.04% to obtain modified color masterbatch. Take 2.0 kg of commercially available negative ion masterbatch (the main component is tourmaline-tourmaline composite powder with a particle size of 300~500 nm) and add it to a high-speed mixer. At the same time, add 60 g of silane coupling agent KH-550 (accounting for 3% of the masterbatch mass). The material was stirred and modified for 2.5 h at 90℃ and 350 rpm, and then transferred to a vacuum oven and dried at 130℃ for 5 h, with the final moisture content controlled to ≤0.04%, to obtain modified negative ion masterbatch; 1540 g of nylon 6 chips, 400 g of modified color masterbatch, and 60 g of leveling agent were mixed evenly to obtain the skin layer compound raw material; 1200 g of nylon 6 chips and 200 g of modified negative ion masterbatch were mixed evenly to obtain the core layer compound raw material; S2. The skin layer compound raw material and the core layer compound raw material are respectively added to a twin-screw extruder for melt extrusion. The temperature of each zone is controlled as follows: Zone 1 255℃, Zone 2 257℃, Zone 3 258℃, Zone 4 259℃, and Zone 5 259℃ to obtain skin layer melt and core layer melt. S3. The sheath melt and core melt are introduced into a metering pump, and the two melts are output at a mass ratio of sheath to core of 3:7. The proportioned melt is then introduced into a composite spinning assembly. The filter unit in this assembly adopts a double-layer nonwoven fabric filter structure (the upper layer is a 77×6×20μm coarse filter and the lower layer is a 50×4×15μm fine filter) to intercept masterbatch agglomerates in stages and ensure the cleanliness of the melt. It then enters a concentric sheath-core spinneret (a single hole consists of a central core hole and an outer annular gap) for extrusion molding to form a primary fiber with a sheath-core composite structure. S4. The raw fibers are cooled by side blowing through a side blowing window, where the side blowing temperature is 22.5℃ and the wind speed is 0.50 m / s. Then, FDY oil (6352AY) with a concentration of 7% is applied to the bundled fibers at a bundling point 1000 mm away from the spinneret and 190 mm away from the side blowing window. After that, the fibers pass through a pre-networker and then through a cold roller and a hot roller for stretching and shaping. The hot roller temperature is 165℃ and the stretching ratio is 1.23. After the main network treatment, the fibers are wound on a winding machine at a speed of 4800 m / min and a winding angle of 5.3° to obtain 20D / 7F negative ion silver-gray nylon 6 fiber.

[0026] The performance of the prepared 20D / 7F negative ion silver-gray nylon 6 fiber was tested. The results showed that the fiber had a breaking strength of 4.56 cN / dtex and a breaking elongation of 38.82%, indicating that the fiber fully maintained the excellent mechanical properties of the nylon 6 matrix after the introduction of functional and color components. In terms of color fastness, its wash fastness and rubbing fastness both reached grade 4.5, which is significantly higher than that of conventional products, proving the effectiveness of the core-sheath structure isolation and masterbatch modification strategy in solving the problem of uneven dyeing and improving color fastness.

[0027] Example 2 This embodiment provides a method for preparing negative ion colored nylon 6 fiber, including the following steps: S1. Take 2.0 kg of bright silver-gray masterbatch with a particle size of 200~400 nm and add it to a high-speed mixer. At the same time, add 200 g of polyurethane-type polymeric dispersant and 100 g of leveling accelerator. Stir at 150℃ and 500 rpm for 3.5 h, and then dry until the moisture content is ≤0.04% to obtain modified color masterbatch. Take 2.0 kg of commercially available negative ion masterbatch (the main component is tourmaline-tourmaline composite powder with a particle size of 300~500 nm) and add it to a high-speed mixer. At the same time, add 20 g of silane coupling agent KH-550 (accounting for 1% of the masterbatch mass). The material was stirred and modified for 3 hours at 100℃ and 300 rpm, and then transferred to a vacuum oven and dried at 150℃ for 4 hours, with the final moisture content controlled to ≤0.04%, to obtain modified negative ion masterbatch; 1470 g of nylon 6 chips, 500 g of modified color masterbatch, and 30 g of leveling agent were mixed evenly to obtain the skin layer compound raw material; 1260 g of nylon 6 chips and 140 g of modified negative ion masterbatch were mixed evenly to obtain the core layer compound raw material; S2. The skin layer compound raw material and the core layer compound raw material are respectively added to a twin-screw extruder for melt extrusion. The temperature of each zone is controlled as follows: Zone 1 262℃, Zone 2 268℃, Zone 3 268℃, Zone 4 268℃, and Zone 5 268℃ to obtain skin layer melt and core layer melt. S3. The sheath melt and core melt are introduced into a metering pump, and the two melts are output at a mass ratio of sheath to core of 5:5. The prepared melt is introduced into a composite spinning assembly. The filter unit in this assembly adopts a double-layer nonwoven filter structure (the upper layer is a 77×6×20μm coarse filter and the lower layer is a 50×4×15μm fine filter) to intercept masterbatch agglomerates in stages and ensure the cleanliness of the melt. Then it enters a concentric sheath-core spinneret (a single hole consists of a central core hole and an outer annular gap) for extrusion molding to form a primary fiber with a sheath-core composite structure. S4. The raw fibers are cooled by side blowing through a side blowing window, where the side blowing temperature is 25℃ and the wind speed is 0.45 m / s. Then, at the bundling point 1100 mm away from the spinneret and 250 mm away from the side blowing window, 8% FDY oil (6352AY) is applied to the bundled fibers. After that, the fibers pass through a pre-networker, and then through a cold roller and a hot roller for stretching and shaping. The hot roller temperature is 170℃ and the stretching ratio is 1.5. After the main network treatment, the fibers are wound on a winding machine at a speed of 4200 m / min and a winding angle of 5.0° to obtain 20D / 7F negative ion silver-gray nylon 6 fiber.

[0028] The performance of the prepared 20D / 7F negative ion silver-gray nylon 6 fiber was tested. The results showed that the fiber had a breaking strength of 4.50 cN / dtex and a breaking elongation of 42.0%, indicating that the fiber fully maintained the excellent mechanical properties of the nylon 6 matrix after the introduction of functional and color components. In terms of color fastness, its wash fastness and rubbing fastness both reached grade 4.5, which is significantly higher than that of conventional products, proving the effectiveness of the core-sheath structure isolation and masterbatch modification strategy in solving the problem of uneven dyeing and improving color fastness.

[0029] Example 3 This embodiment provides a method for preparing negative ion colored nylon 6 fiber, including the following steps: S1. Take 2.0 kg of bright silver-gray masterbatch with a particle size of 200~400 nm and add it to a high-speed mixer. At the same time, add 150 g of polyurethane-type polymeric dispersant and 100 g of leveling accelerator. Stir at 180℃ and 300 rpm for 3 h, then dry until the moisture content is ≤0.04% to obtain modified color masterbatch. Take 2.0 kg of commercially available negative ion masterbatch (the main component is tourmaline-tourmaline composite powder with a particle size of 300~500 nm) and add it to a high-speed mixer. At the same time, add 40 g of silane coupling agent KH-550 (accounting for 2% of the masterbatch mass). The material was stirred and modified for 2 hours at 80℃ and 400 rpm, and then transferred to a vacuum oven and dried at 120℃ for 6 hours, with the final moisture content controlled to ≤0.04%, to obtain modified negative ion masterbatch. 1830 g of nylon 6 chips, 160 g of modified color masterbatch, and 10 g of leveling accelerator were mixed evenly to obtain the skin layer compound raw material. 1330 g of nylon 6 chips and 70 g of modified negative ion masterbatch were mixed evenly to obtain the core layer compound raw material. S2. The skin layer compound raw material and the core layer compound raw material are respectively added to a twin-screw extruder for melt extrusion. The temperature of each zone is controlled as follows: Zone 1 253℃, Zone 2 254℃, Zone 3 255℃, Zone 4 256℃, and Zone 5 257℃ to obtain skin layer melt and core layer melt. S3. The sheath melt and core melt are introduced into a metering pump, and the two melts are output at a mass ratio of sheath to core of 4:6. The proportioned melt is introduced into a composite spinning assembly. The filter unit in this assembly adopts a double-layer nonwoven filter structure (the upper layer is a 77×6×20μm coarse filter and the lower layer is a 50×4×15μm fine filter) to intercept masterbatch agglomerates in stages and ensure the cleanliness of the melt. Then it enters a concentric sheath-core spinneret (a single hole consists of a central core hole and an outer annular gap) for extrusion molding to form a primary fiber with a sheath-core composite structure. S4. The raw fibers are cooled by side blowing through a side blowing window, where the side blowing temperature is 20℃ and the wind speed is 0.40 m / s. Then, FDY oil (6352AY) with a concentration of 6% is applied to the bundled fibers at a bundling point 1300 mm away from the spinneret and 150 mm away from the side blowing window. After that, the fibers pass through a pre-networker and then through a cold roller and a hot roller for stretching and shaping. The hot roller temperature is 150℃ and the stretching ratio is 1.1. After the main network treatment, the fibers are wound on a winding machine at a speed of 4500 m / min and a winding angle of 6.0° to obtain 20D / 7F negative ion colored yarn nylon 6 fiber.

[0030] The performance of the prepared 20D / 7F negative ion silver-gray nylon 6 fiber was tested. The results showed that the fiber had a breaking strength of 4.80 cN / dtex and a breaking elongation of 40.00%, indicating that the fiber fully maintained the excellent mechanical properties of the nylon 6 matrix after the introduction of functional and color components. In terms of color fastness, its wash fastness and rubbing fastness both reached grade 4.5, which is significantly higher than that of conventional products, proving the effectiveness of the core-sheath structure isolation and masterbatch modification strategy in solving the problem of uneven dyeing and improving color fastness.

[0031] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A negative ion colored yarn nylon 6 fiber, characterized in that, The product adopts a core-skin composite structure, including a skin layer and a core layer; the skin layer is a modified matrix of modified color masterbatch and nylon 6 chips; the core layer is a modified matrix of modified negative ion masterbatch and nylon 6 chips; the mass ratio of the skin layer to the core layer is 3:7~5:

5.

2. The negative ion colored yarn nylon 6 fiber according to claim 1, characterized in that, The modified color masterbatch is prepared by mixing and treating the color masterbatch with a polyurethane-type polymeric dispersant and a leveling accelerator; wherein the amount of polyurethane-type polymeric dispersant is 5-10% of the mass of the color masterbatch, and the particle size of the color masterbatch is 200-400 nm.

3. The negative ion colored yarn nylon 6 fiber according to claim 1, characterized in that, The modified negative ion masterbatch is prepared by modifying the negative ion masterbatch with silane coupling agent KH-550; wherein, the amount of silane coupling agent KH-550 added is 1~3% of the mass of the negative ion masterbatch; the negative ion masterbatch contains tourmaline composite powder with a particle size of 300~500 nm.

4. The negative ion colored yarn nylon 6 fiber according to claim 1, characterized in that, The modified negative ion masterbatch added to the core layer accounts for 5-14.3% of the total mass of the core layer; the modified color masterbatch added to the skin layer accounts for 8-25% of the total mass of the skin layer.

5. A method for preparing negative ion colored yarn nylon 6 fiber as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Mix nylon 6 chips and modified color masterbatch evenly to obtain the skin layer compound material; mix nylon 6 chips and modified negative ion masterbatch evenly to obtain the core layer compound material. S2. The core layer compound raw material and the skin layer compound raw material are respectively melt-extruded through a twin-screw extruder to obtain a melt; S3. The melt is transported to the spinning box by a metering pump and extruded through the concentric core-sheath spinneret in the composite spinning assembly to form primary fibers with a core-sheath composite structure. S4. The initial fibers are cooled by side blowing through the side blowing window, then bundled and oiled at the bundling point, stretched and shaped, networked and wound to obtain negative ion colored yarn nylon 6 fiber.

6. The method for preparing negative ion colored yarn nylon 6 fiber as described in claim 5, characterized in that, In step S1, a leveling accelerator is also added to the leather blending raw materials, and the amount of leveling accelerator added is 0.5~3% of the total mass of the leather.

7. The method for preparing negative ion colored yarn nylon 6 fiber according to claim 5, characterized in that, In step S2, the temperature control of each zone of the twin-screw extruder is as follows: Zone 1 253~262℃, Zone 2 254~268℃, Zone 3 255~268℃, Zone 4 256~268℃, and Zone 5 257~268℃.

8. The method for preparing negative ion colored yarn nylon 6 fiber according to claim 5, characterized in that, In step S3, the composite spinning assembly contains a filter assembly, which adopts a double-layer nonwoven filter structure. The upper filter has a size of 77×6×20μm, and the lower filter has a size of 50×4×15 μm.

9. The method for preparing negative ion colored yarn nylon 6 fiber according to claim 5, characterized in that, In step S4, the side-blowing air temperature is 20~25℃ and the air speed is 0.4~0.5 m / s; the oil used for bundling is FDY oil with a concentration of 6~8%; the stretching and shaping includes sequential stretching with cold rollers and hot rollers, wherein the temperature of the hot rollers is 150~170℃ and the stretching ratio is 1.1~1.5; the winding speed is 4200~4800 m / min and the initial value of the winding forming angle is 5.0~6.

0.

10. The method for preparing negative ion colored yarn nylon 6 fiber according to claim 5, characterized in that, The distance between the cluster point and the spinneret is 1000~1300 mm; the distance between the cluster point and the side air window is 150~250 mm.