Spinning process of flame-retardant ultrafine denier functional nylon and product thereof

Abstract

The application provides a spinning process of flame-retardant ultrafine functional chinlon and a product thereof. The product takes low-melting-point nylon resin as a base body, adds 3-8wt% of guanidine modified agent of 3-chloro-s-triazine phosphite triethyl ester, and solves the technical problems of easy broken ends, easy bonding of finished yarn and bad unwinding of low-melting-point chinlon in the process of ultrafine spinning through the optimization of the whole process of raw material pretreatment, melting control, cooling forming, drafting setting and winding. The low-melting-point nylon resin is composed of PA6 or PA66 base body, 0.3-5wt% of divalent metal ion compound, 0.05-2wt% of trivalent rare earth ion compound and no more than 2wt% of auxiliary additive, and has low melting point, high mechanical property and persistent flame retardancy through synergistic modification. The optimized spinning process makes the product monofilament fineness ≤0.8dtex, the melting point reduced by 180℃ or less, the limiting oxygen index ≥30%, the breaking strength ≥5.0cN / dtex, the spinning broken end rate <0.5%, and the finished yarn has no bonding and smooth unwinding.

Description

Technical Field

[0001] This invention relates to the field of textile technology, specifically to a spinning process and product of flame-retardant ultrafine denier functional nylon. Background Technology

[0002] Nylon resin (nylon) is widely used in the textile industry due to its excellent mechanical properties, abrasion resistance, and processing adaptability. With the upgrading of market demand, functional nylons with low melting point, flame retardancy, and ultra-fine denier properties have become a research hotspot, which can meet the application needs of composite textiles, high-end protective applications, and other scenarios.

[0003] In existing technologies, during the ultrafine denier spinning process, the reduced melting point leads to decreased melt viscosity and uneven fiber cooling rates, easily causing problems such as yarn breakage, finished yarn adhesion, and difficulty in unwinding. While flame-retardant nylon can achieve long-lasting flame retardancy, combining flame-retardant modification with low melting point characteristics makes it difficult to coordinate the compatibility of the two modification systems and the matching of spinning process parameters, further exacerbating the spinning processing challenges. Simultaneously, traditional ultrafine denier spinning processes are designed for conventional nylon and cannot adapt to the resin characteristics after low-melting-point flame-retardant modification. This results in products either failing to meet ultrafine denier specifications or exhibiting a decline in functional indicators (low melting point, flame retardancy), making it difficult to balance functionality, fineness, and processing stability.

[0004] Therefore, developing a flame-retardant ultrafine denier functional nylon that can synergistically combine low melting point and flame-retardant functions, and optimizing the spinning process to solve processing challenges, as well as its preparation method, has significant practical application value. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a spinning process and product of flame-retardant ultrafine denier functional nylon. By optimizing the entire process of raw material pretreatment, melt control, cooling and molding, stretching and setting, and winding and taking up the yarn, the invention solves the problems of easy breakage, easy adhesion of finished yarn, and difficulty in unwinding of low melting point nylon during ultrafine denier spinning. At the same time, it achieves the synergy of flame retardancy, ultrafine denier, low melting point and excellent mechanical properties.

[0006] This invention is implemented as follows: A spinning process for flame-retardant ultrafine denier functional nylon includes the following steps: S1: Preparation of low-melting-point nylon resin S11: Mix low-melting-point nylon resin raw materials and modifiers, and premix them for 10-30 minutes at room temperature to 60°C using a high-speed mixer, ribbon mixer or drum mixer to obtain a uniform premix. S12: Add the premixed material to a twin-screw extruder and melt-blend it at 200-240℃ and screw speed of 100-300 r / min. After extrusion and pelletizing, vacuum dry at 80-95℃ for 4-8 h to obtain low-melting-point nylon resin chips with a moisture content of ≤0.05%. S2: Pretreatment of spinning raw materials Low-melting-point nylon resin chips and metered modifiers are added to a drying device and dried in stages at 85-100℃. The first stage is dried at 85-90℃ for 2-3 hours, and the second stage is dried at 95-100℃ for 2-3 hours. This ensures that the moisture content of the raw materials after mixing is ≤0.03% to avoid breakage caused by melt bubbles. S3: Melt spinning control S31: Add the dried mixed raw materials to the reactor, purge with nitrogen for protection, heat to 250-265℃, stir and melt at a rate of 60-90r / min for 1.5-2.5h to avoid resin degradation caused by high temperature and form a uniform modified melt; S32: The modified melt is extruded through a spinneret with a spinneret orifice diameter of 0.1-0.2 mm and a number of orifices ≥1000. The melt extrusion pressure is controlled at 9-11 MPa to ensure uniform forming and stable extrusion of ultrafine denier fibers and reduce the risk of fiber breakage. S4: Cooling and Forming Optimization The cooling method adopts a side-blowing air cooling method. The cooling air is a dehumidified laminar flow air with a temperature of 18-22℃, a wind speed of 0.9-1.1m / s, a cooling distance of 90-110mm, and an angle of 35-40° between the air direction and the fiber running direction. This achieves rapid and uniform cooling of the ultra-fine denier fibers and prevents surface adhesion. S5: Drawing and Shaping Process S51: The cooled nascent fibers are subjected to two-stage drawing. The first stage drawing ratio is 1.6-2.2 times, and the drawing temperature is 65-75℃. The second stage drawing ratio is 2.1-2.8 times, and the drawing temperature is 105-115℃. The total drawing ratio is 3.5-5.0 times, which avoids stress concentration during drawing that could cause breakage of the ultrafine denier fibers. S52: After stretching, heat setting is performed at a temperature of 125-140℃ for 35-50 seconds. During the heat setting process, a constant tension of 0.6-0.9 cN / dtex is applied to improve the structural stability of the ultrafine denier fiber and reduce adhesion. S6: Optimized winding and take-up A variable frequency winding machine is used with a winding speed of 2900-3300m / min and a winding tension of 0.4-0.5cN / dtex. A silicon-coated anti-adhesion yarn guide is used during winding. After the yarn is wound into a bobbin, it is kept at a constant temperature of 42-48℃ for 15-20 hours to eliminate internal stress in the fiber and ensure that the ultra-fine denier finished yarn is non-adhesive and unwinds smoothly. S7: Finished Product Inspection and Packaging The wound fibers are tested for single filament fineness, breaking strength, and flame retardancy. Qualified products are individually sealed in packaging to prevent sticking during storage.

[0007] Furthermore, the melt blending reaction temperature in step S31 is preferably 255-260℃ to balance the reaction efficiency of the modifier and the stability of the resin, thus ensuring the mechanical properties of the ultrafine denier fiber.

[0008] Furthermore, in step S4, the relative humidity of the side-blowing air is controlled at 45-55% to further improve the uniformity of cooling and prevent the ultrafine denier fibers from sticking together due to uneven cooling.

[0009] Further, the low-melting-point nylon resin in step S1 includes nylon matrix resin, metal ion compound, rare earth ion compound and auxiliary additives, and the modifier is guanidine monochlorotriazine triethyl phosphite, which is added in an amount of 3-8% of the weight of the low-melting-point nylon resin.

[0010] Furthermore, the nylon matrix resin is selected from PA6 or PA66, and the relative viscosity is 2.0-3.5; The metal ion compound is a divalent metal ion selected from at least one of Zn²⁺, Ca²⁺, Cu²⁺, Mg²⁺, and Mn²⁺, and the amount added is 0.3-5 wt% of the nylon matrix resin. The compound type is at least one of acetate, nitrate, chloride, and carbonate. The rare earth ion compound is a trivalent rare earth ion, selected from at least one of La³⁺, Ce³⁺, Y³⁺, ​​Nd³⁺, Sm³⁺ and other lanthanide ions, and the amount added is 0.05-2 wt% of the mass of the nylon matrix resin. The compound type is at least one of rare earth nitrate, rare earth chloride, and rare earth acetate. Furthermore, step S1 also includes auxiliary additives, which are selected from at least one of antioxidants, lubricants, and UV stabilizers, and the total amount added does not exceed 2 wt% of the mass of the nylon matrix resin.

[0011] Furthermore, the amount of the modifier added is preferably 5% of the weight of the low-melting-point nylon resin.

[0012] Furthermore, the product prepared by the aforementioned spinning process has a single filament fineness ≤ 0.8 dtex, melting point ≤ 180℃, limiting oxygen index ≥ 30%, breaking strength ≥ 5.0 cN / dtex, and spinning breakage rate < 0.5%.

[0013] The present invention has the following advantages: Excellent synergy of functions: The product has low melting point, long-lasting flame retardancy (LOI≥30%, B1 grade, stable performance after 50 washes) and ultra-fine denier (≤0.8dtex) characteristics, with tensile strength retention rate>85%, balancing functionality and mechanical properties; Improved processing stability: Through precise optimization of raw material drying, melting temperature, cooling method, stretching and winding processes, the problems of breakage, adhesion and unwinding during the spinning of low-melting-point flame-retardant nylon ultra-fine denier yarn are completely solved, and the yarn qualification rate is increased to over 95%. Environmentally friendly and safe: Low-melting-point modification prevents migration pollution, and the chemical bonding of flame-retardant modifiers prevents the release of toxic gases, meeting the requirements of green production; High process adaptability: Based on the modification of existing melt spinning equipment, no major new equipment is required, which is easy to industrialize and suitable for a variety of high-end textile scenarios. Detailed Implementation

[0014] This invention relates to a spinning process and product of flame-retardant ultrafine denier functional nylon. The spinning process employs a segmented drying process, strictly controlling the raw material moisture content to ≤0.03% to eliminate melt bubbles caused by moisture, thus reducing fiber breakage at the source. The melting temperature is controlled at 250-265℃ to match the characteristics of low-melting-point resins, avoiding resin degradation leading to uneven melt distribution and ensuring the molding stability of the ultrafine denier fibers. A fine pore size of 0.1-0.2mm and a density of ≥1000 mm are used. The perforated spinneret design, combined with dehumidifying laminar flow side blowing, precisely controls temperature, wind speed, and wind direction to achieve rapid and uniform cooling of ultra-fine denier fibers, eliminating adhesion caused by uneven cooling. A two-stage gradient drawing process, combined with medium-low temperature heat setting and constant tension control, reduces stress concentration during drawing, preventing fiber breakage due to insufficient strength and improving fiber structural stability. A silicon-coated anti-adhesion guide and constant low-tension winding, followed by constant-temperature placement after winding to eliminate internal stress, solve the adhesion problem caused by the large contact area between ultra-fine denier fibers, ensuring smooth unwinding.

[0015] Simultaneously, it combines specific raw materials, namely, low-melting-point nylon resin as the matrix, with the addition of 3-8wt% guanidine monochlorotriazine triethyl phosphite modifier. The low-melting-point nylon resin is composed of PA6 or PA66 matrix, divalent metal ion compounds (Zn²⁺, Ca²⁺, etc.), trivalent rare earth ion compounds (La³⁺, Ce³⁺, etc.), and auxiliary additives. The metal ions and rare earth ions intervene in the molecular chain hydrogen bond network and crystalline phase region through coordination, lowering the melting point while retaining high mechanical properties. The modifier is chemically bonded to the nylon molecular chain, achieving long-lasting flame retardancy without affecting the stability of the low-melting-point modified system. The product has a single filament fineness ≤0.8dtex, combining ultra-fine denier softness with multifunctional integrated advantages.

[0016] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0017] Example 1 Preparation of low-melting-point nylon resin: Nylon matrix: PA6, relative viscosity 2.6; Metal ion compound: Zinc acetate (Zn²⁺), 1.5 wt% (relative to PA6 mass); Rare earth ionic compound: Lanthanum nitrate (La³⁺), added at 0.8 wt% (relative to the mass of PA6); Modifier: Guanidine monochlorotriazine triethyl phosphite, added at 3 wt% (relative to the mass of low melting point PA6). Preparation process: S1: PA6 chips were dried at 80℃ for 4 hours, mixed with zinc acetate and lanthanum nitrate at high speed for 15 minutes, melt-blended in a twin-screw extruder at 210-225℃ and 200 r / min, granulated underwater, and vacuum-dried at 85℃ for 6 hours to obtain low-melting-point PA6 resin chips with a moisture content of 0.04%.

[0018] S2: The mixed raw materials were dried in stages, at 85℃ for 2.5 hours and at 95℃ for 2.5 hours, with a moisture content of 0.02%. S3: The reactor is protected by nitrogen. The reaction is carried out at 255℃ and 70r / min for 2 hours. The melt is extruded through a 0.15mm orifice spinneret with 1200 holes at a pressure of 10MPa. S4: Side blowing 20℃, 1.0m / s, cooling distance 100mm, wind direction angle 38°, relative humidity 50%; S5: First-stage draw 1.8 times (70℃), second-stage draw 2.5 times (110℃), total draw 4.5 times; heat set at 130℃ for 40 seconds, tension 0.7cN / dtex; S6: Winding speed 3100m / min, tension 0.45cN / dtex, silicon-coated wire guide, placed at 45℃ for 18h; Product performance: Monofilament fineness: 0.7 dtex; Melting point: 171.2℃; Limiting oxygen index: 31.1%, vertical combustion B1 grade, LOI 27.2% after 50 washes; Tensile strength: 5.3 cN / dtex, elongation at break: 37%; Processing performance: breakage rate 0.3%, finished yarn has no adhesion, unwinding tension fluctuation ≤ ±0.05cN / dtex.

[0019] Example 2 Preparation of low-melting-point nylon resin: Nylon matrix: PA66, relative viscosity 2.8; Metal ion compound: calcium carbonate (Ca²⁺), 2.0 wt% (relative to the mass of PA66); Rare earth ionic compound: cerium chloride (Ce³⁺), added at 1.2 wt% (relative to the mass of PA66); Modifier: Guanidine monochlorotriazine triethyl phosphite, added at 5 wt% (relative to the mass of low melting point PA66). Preparation process: S1: PA66 chips were dried at 90℃ for 5 hours, mixed with calcium carbonate and cerium chloride for 20 minutes, melt-blended in a twin-screw extruder at 220-230℃ and 250 r / min, granulated underwater, and vacuum-dried at 90℃ for 5 hours to obtain low-melting-point PA66 resin chips with a moisture content of 0.03%.

[0020] S2: The mixed raw materials are dried in stages, at 90℃ for 2 hours and at 100℃ for 3 hours, with a moisture content of 0.02%. S3: The reactor is protected by nitrogen, and the reaction is carried out at 260℃ and 80r / min for 1.8h with stirring. The melt is extruded through a 0.12mm orifice spinneret with 1500 holes at a pressure of 10.5MPa. S4: Side blowing 21℃, 1.05m / s, cooling distance 95mm, wind direction angle 36°, relative humidity 48%; S5: First-stage draw 1.7 times (72℃), second-stage draw 2.3 times (112℃), total draw 4.0 times; heat set at 135℃ for 38 seconds, tension 0.8cN / dtex; S6: Winding speed 3200m / min, tension 0.48cN / dtex, silicon-coated wire guide, placed at 46℃ for 19h; Product performance: Monofilament fineness: 0.6 dtex; Melting point: 178℃; Limiting Oxygen Index (LOI): 31.7%, Vertical Burning Class B1, LOI 30.7% after 50 washes; Tensile strength: 5.4 cN / dtex, elongation at break: 34%; Processing performance: breakage rate of 0.2%, finished yarn is non-adhesive, unwinding is smooth and there is no jamming.

[0021] Example 3 Preparation of low-melting-point nylon resin: Nylon matrix: PA6, relative viscosity 2.3; Metal ion compound: a mixture of manganese acetate (Mn²⁺) and copper nitrate (Cu²⁺), with a total addition of 0.8 wt% (relative to the mass of PA6); Rare earth ionic compound: samarium acetate (Sm³⁺), added at 0.2 wt% (relative to the mass of PA6); Auxiliary additive: UV stabilizer UV-531, 0.4wt% (relative to the mass of PA6). Preparation process: PA6 chips are dried at 75℃ for 7 hours, mixed with metal ion compounds, rare earth ion compounds and UV-531 roller mixer for 30 minutes, melt-blended in a twin-screw extruder at 205-215℃ and 150 r / min, granulated underwater and vacuum-dried at 88℃ for 7 hours to obtain low-melting-point PA6 resin chips with a moisture content of 0.04%.

[0022] Optimize the spinning process: Modifier: Guanidine monochlorotriazine triethyl phosphite, added at 8 wt% (relative to the mass of low melting point PA6). Specific steps: S2: The mixed raw materials are dried in stages, at 88℃ for 3 hours and at 98℃ for 2 hours, with a moisture content of 0.03%. S3: The reactor is protected by nitrogen. The reaction is carried out at 265℃ and 90r / min for 1.5h with stirring. The melt is extruded through a 0.1mm orifice spinneret with 2000 holes at a pressure of 11MPa. S4: Side blowing 22℃, 1.1m / s, cooling distance 105mm, wind direction angle 40°, relative humidity 52%; S5: First-stage draw 2.0 times (75℃), second-stage draw 2.6 times (115℃), total draw 5.0 times; heat set at 140℃ for 35 seconds, tension 0.9cN / dtex; S6: Winding speed 3300m / min, tension 0.5cN / dtex, silicon-coated wire guide, placed at 48℃ for 20h; Product performance: Monofilament fineness: 0.5 dtex; Melting point: 175.7℃; Limiting Oxygen Index (LOI): 33.7%, Vertical Burning Class B1, LOI 33.0% after 50 washes; Tensile strength: 5.2 cN / dtex, elongation at break: 31%, UV resistance (tensile strength retention after 1000 h of QUV aging): 90%; Processing performance: breakage rate of 0.4%, no bonding of finished yarn, and unwinding efficiency of over 98%.

[0023] The above embodiments demonstrate that the present invention, through optimization of the entire process from raw material pretreatment, melt control, spinneret cooling, drawing and setting, and winding, precisely adapts to the spinning characteristics of low-melting-point flame-retardant ultrafine denier nylon, successfully solving the core problems of easy breakage, finished product adhesion, and difficulty in unwinding ultrafine denier spinning. At the same time, it maintains the ultrafine denier characteristics, low melting point, flame retardancy, and high mechanical properties of the product. The process is stable and reliable, and suitable for industrial production.

[0024] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A spinning process for flame-retardant ultrafine denier functional nylon, characterized in that: Includes the following steps: S1: Preparation of low-melting-point nylon resin S11: Mix low-melting-point nylon resin raw materials and modifiers, and premix them for 10-30 minutes at room temperature to 60°C using a high-speed mixer, ribbon mixer or drum mixer to obtain a uniform premix. S12: Add the premixed material to a twin-screw extruder and melt-blend it at 200-240℃ and screw speed of 100-300 r / min. After extrusion and pelletizing, vacuum dry at 80-95℃ for 4-8 h to obtain low-melting-point nylon resin chips with a moisture content of ≤0.05%. S2: Pretreatment of spinning raw materials Low-melting-point nylon resin chips and metered modifiers are added to a drying device and dried in stages at 85-100℃. The first stage is dried at 85-90℃ for 2-3 hours, and the second stage is dried at 95-100℃ for 2-3 hours. This ensures that the moisture content of the raw materials after mixing is ≤0.03% to avoid breakage caused by melt bubbles. S3: Melt spinning control S31: Add the dried mixed raw materials to the reactor, purge with nitrogen for protection, heat to 250-265℃, stir and melt at a rate of 60-90r / min for 1.5-2.5h to avoid resin degradation caused by high temperature and form a uniform modified melt; S32: The modified melt is extruded through a spinneret with a spinneret orifice diameter of 0.1-0.2 mm and a number of orifices ≥1000. The melt extrusion pressure is controlled at 9-11 MPa to ensure uniform forming and stable extrusion of ultrafine denier fibers and reduce the risk of fiber breakage. S4: Cooling and Forming Optimization The cooling method adopts a side-blowing air cooling method. The cooling air is a dehumidified laminar flow air with a temperature of 18-22℃, a wind speed of 0.9-1.1m / s, a cooling distance of 90-110mm, and an angle of 35-40° between the air direction and the fiber running direction. This achieves rapid and uniform cooling of the ultra-fine denier fibers and prevents surface adhesion. S5: Drawing and Shaping Process S51: The cooled nascent fibers are subjected to two-stage drawing. The first stage drawing ratio is 1.6-2.2 times, and the drawing temperature is 65-75℃. The second stage drawing ratio is 2.1-2.8 times, and the drawing temperature is 105-115℃. The total drawing ratio is 3.5-5.0 times, which avoids stress concentration during drawing that could cause breakage of the ultrafine denier fibers. S52: After stretching, heat setting is performed at a temperature of 125-140℃ for 35-50 seconds. During the heat setting process, a constant tension of 0.6-0.9 cN / dtex is applied to improve the structural stability of the ultrafine denier fiber and reduce adhesion. S6: Optimized winding and take-up A variable frequency winding machine is used, with a winding speed of 2900-3300m / min and a winding tension of 0.4-0.5cN / dtex. A silicon-coated anti-sticking wire guide is used during winding. After the wire is wound into a bobbin, it is kept at a constant temperature of 42-48℃ for 15-20 hours. S7: Finished Product Inspection and Packaging The wound fibers are tested for single filament fineness, breaking strength, and flame retardancy. Qualified products are individually sealed in packaging.

2. The spinning process according to claim 1, characterized in that: The preferred melting and blending reaction temperature in step S31 is 255-260℃.

3. The spinning process according to claim 1, characterized in that: In step S4, the relative humidity of the side-blowing air is controlled at 45-55%.

4. The spinning process according to claim 1, characterized in that: The low-melting-point nylon resin in step S1 includes nylon matrix resin, metal ion compound, rare earth ion compound and auxiliary additives. The modifier is guanidine monochlorotriazine triethyl phosphite, and the amount added is 3-8% of the weight of the low-melting-point nylon resin.

5. The spinning process according to claim 4, characterized in that: The nylon matrix resin is selected from PA6 or PA66, with a relative viscosity of 2.0-3.5; The metal ion compound is a divalent metal ion selected from at least one of Zn²⁺, Ca²⁺, Cu²⁺, Mg²⁺, and Mn²⁺, and the amount added is 0.3-5 wt% of the nylon matrix resin. The compound type is at least one of acetate, nitrate, chloride, and carbonate. The rare earth ion compound is a trivalent rare earth ion, selected from at least one of La³⁺, Ce³⁺, Y³⁺, ​​Nd³⁺, Sm³⁺ and other lanthanide ions, and is added in an amount of 0.05-2 wt% of the nylon matrix resin. The compound type is at least one of rare earth nitrate, rare earth chloride, and rare earth acetate.

6. The spinning process according to claim 4, characterized in that: Step S1 also includes auxiliary additives, which are selected from at least one of antioxidants, lubricants, and UV stabilizers, and the total amount added does not exceed 2 wt% of the mass of the nylon matrix resin.

7. The spinning process according to claim 4, characterized in that: The preferred amount of the modifier added is 5% of the weight of the low-melting-point nylon resin.

8. The product prepared by the spinning process according to any one of claims 1-7, characterized in that: The product has a single filament fineness of ≤0.8dtex, melting point of ≤180℃, limiting oxygen index of ≥30%, breaking strength of ≥5.0cN / dtex, and spinning breakage rate of <0.5%.