Flame retardant yarn and process for its preparation

Abstract

This invention relates to the field of functional yarn preparation technology, specifically involving raw materials comprising, by mass fraction: 78% polyester chips, 18% aluminum hypophosphite, 2.5% silane coupling agent KH550, 0.8% antioxidant 1010, and 0.7% calcium stearate. The composite flame-retardant components of this invention exhibit a synergistic effect, achieving stable flame-retardant performance at relatively low addition levels, avoiding fiber performance degradation caused by excessive addition of flame retardants. The use of a composite coupling agent to modify the flame retardant significantly improves the interfacial compatibility and dispersion uniformity between the flame retardant and the polymer substrate, effectively reducing flame retardant agglomeration, lowering the breakage rate during spinning, and enhancing production and processing stability.

Description

Technical Field

[0001] This invention relates to the field of functional yarn preparation technology, specifically to a flame-retardant yarn and its preparation process. Background Technology

[0002] The textile industry continues to increase its demand for functional flame-retardant materials. Flame-retardant yarn, as a core raw material, is widely used in many fields such as industrial textiles, interior decoration, and safety protective clothing. Polyester and polyester composite fibers have become the mainstream choice for yarn substrates due to their excellent mechanical properties and processability. However, they are flammable materials and are prone to molten dripping during combustion, which can accelerate the spread of flames and release a large amount of flammable gas, posing a serious safety hazard.

[0003] Existing flame-retardant yarn preparation technologies still have many shortcomings. Although traditional halogen-based flame-retardant materials have a certain flame-retardant effect, they release toxic and harmful gases when burning, which does not meet environmental protection standards and safety requirements, thus limiting their application scenarios. In halogen-free flame-retardant systems, single flame retardants have problems such as insufficient flame-retardant efficiency and excessive addition, which can easily lead to fiber embrittlement and a significant decrease in mechanical properties. Most inorganic flame retardants have poor compatibility with polymer substrates and are prone to agglomeration when not modified, which not only affects spinning stability but also increases the breakage rate during the production process and reduces the finished product qualification rate.

[0004] Furthermore, existing technologies mostly employ single coupling agent modification, which cannot simultaneously address the dispersibility and interfacial bonding of flame retardants. Flame retardant components are prone to detachment after washing, making it difficult to guarantee flame retardant durability. Some processes do not optimize spinning and finishing parameters, resulting in the inability to effectively eliminate internal fiber stress and leading to poor yarn flexibility and dimensional stability. At the same time, existing flame retardant solutions cannot simultaneously achieve synergistic improvements in flame retardancy, mechanical properties, processing stability, washability durability, and environmental friendliness, failing to meet the usage requirements of high-end flame retardant textiles. Summary of the Invention

[0005] The primary objective of this invention is to provide a flame-retardant yarn and its preparation process.

[0006] A further objective of this invention is to provide a flame-retardant yarn, wherein the raw materials, by mass fraction, comprise: 78% polyester chips, 18% aluminum hypophosphite, 2.5% silane coupling agent KH550, 0.8% antioxidant 1010, and 0.7% calcium stearate.

[0007] Preferably, the polyester chips are replaced with 75%, the aluminum hypophosphite is 12%, and flame-retardant aluminum hydroxide is added at 10%, with the mass ratio of aluminum hypophosphite to flame-retardant aluminum hydroxide being 6:5. The silane coupling agent KH550 is 2%, the antioxidant 1010 is 0.6%, and calcium stearate is replaced with zinc stearate at 0.4%.

[0008] Preferably, the polyester chips are 72%, the aluminum hypophosphite is 13%, the flame-retardant aluminum hydroxide is 12%, the silane coupling agent KH550 is replaced with 1.2% silane coupling agent KH560, and 1.0% titanate coupling agent NDZ311 is added, zinc stearate is replaced with 0.8% calcium stearate, and 0.2% nano silica is added.

[0009] Preferably, the polyester chips are replaced with 70% polyester-nylon composite chips, the aluminum hypophosphite is 8%, coated red phosphorus is added at 7%, the flame-retardant aluminum hydroxide is 12%, the silane coupling agent KH560 is 1.5%, the titanate coupling agent NDZ311 is 1.0%, the antioxidant 1010 is 0.7%, calcium stearate is replaced with 0.5% zinc stearate, and nano silica is 0.3%.

[0010] Preferably, the polyester-nylon composite chips comprise 68%, the aluminum hypophosphite comprises 7%, the coated red phosphorus comprises 8%, the flame-retardant aluminum hydroxide comprises 14%, the silane coupling agent KH560 comprises 1.8%, the titanate coupling agent NDZ311 comprises 1.2%, the antioxidant 1010 comprises 0.6%, zinc stearate is replaced with calcium stearate 0.4%, and nano silica comprises 0.2%.

[0011] A process for preparing the flame-retardant yarn includes, in sequence, flame retardant pretreatment, melt blending, melt spinning, and post-treatment steps; the flame retardant pretreatment involves mixing flame-retardant components with a coupling agent, followed by high-speed dispersion and ultrasonic treatment to obtain a modified flame retardant; the melt blending involves drying chips, adding them to a twin-screw extruder along with the modified flame retardant, antioxidant 1010, and stearate, and then extruding and pelletizing them to obtain flame-retardant masterbatch; the melt spinning involves drying the flame-retardant masterbatch and spinning it to obtain nascent fibers; and the post-treatment involves sequentially oiling, stretching, heat-setting, and winding the nascent fibers to obtain the flame-retardant yarn.

[0012] Preferably, the high-speed dispersion temperature for flame retardant pretreatment is 75℃-95℃, the rotation speed is 3500rpm-4500rpm, and the dispersion time is 20min-40min; the ultrasonic treatment frequency is 30kHz-40kHz, the power is 600W-1000W, and the treatment time is 10min-20min.

[0013] Preferably, the drying temperature of the chips in the melt blend is 130℃-145℃, and the drying time is 4h-5.5h; the twin-screw extruder speed is 220rpm-260rpm, and the gradient heating temperature is 260℃-305℃.

[0014] Preferably, the drying temperature of the flame retardant masterbatch in melt spinning is 120℃-135℃, and the drying time is 3h-4.5h; the spinning temperature is 280℃-300℃, and the winding speed is 3500m / min-4500m / min.

[0015] Preferably, the post-treatment oiling rate is 1.8%-2.5%, the draw ratio is 3.5-5.0 times, the heat setting temperature is 150℃-170℃, and the heat setting time is 15min-25min.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. This invention adopts a halogen-free composite flame retardant system, abandoning traditional halogen-based flame retardant components. No toxic or harmful gases are released during the combustion process, which fully complies with environmental protection standards and greatly improves the safety of use.

[0018] 2. The composite flame-retardant components of this invention form a synergistic effect, which can achieve a stable flame-retardant effect at a low addition amount, avoiding the deterioration of fiber performance caused by excessive addition of flame retardant; the flame retardant is modified by a composite coupling agent, which significantly improves the interfacial compatibility and dispersion uniformity between the flame retardant and the polymer substrate, effectively reduces the problem of flame retardant agglomeration, reduces the fiber breakage rate during spinning, and improves the stability of production and processing.

[0019] 3. The addition of synergistic components in this invention can optimize the structure of char produced by combustion and enhance the density of the char layer. This not only strengthens the flame retardant effect but also improves the mechanical properties and flexibility of the yarn. Through segmented drafting and precise heat setting processes, it effectively eliminates internal stress in the fiber, improves the crystallinity and dimensional stability of the yarn, and ensures the stability of the finished product shape.

[0020] 4. The preparation process of this invention has strong adaptability and can produce flame-retardant yarns of both conventional and fine denier specifications, expanding the application scenarios of the products. Moreover, the flame-retardant components are firmly bonded to the substrate and can maintain stable flame-retardant performance even after multiple water washes, exhibiting excellent durability. At the same time, this invention can effectively reduce the amount of smoke released during the combustion process, improving the safety of use. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0022] Example 1:

[0023] The raw material composition, by mass fraction, is: polyester chips 78%, aluminum hypophosphite 18%, silane coupling agent KH550 2.5%, antioxidant 1010 0.8%, and calcium stearate 0.7%. This embodiment uses a single phosphorus-based flame retardant system, with the silane coupling agent modified separately. The raw material specifications are as follows: polyester chips intrinsic viscosity 0.68 dL / g, melting point 255℃; aluminum hypophosphite purity 99.5%, particle size 10 μm; silane coupling agent KH550 purity 98%; antioxidant 1010 purity 99%; and calcium stearate purity 98%.

[0024] Preparation process:

[0025] Flame retardant pretreatment: Using an SHR-10A high-speed mixer, aluminum hypophosphite was placed into the equipment and silane coupling agent KH550 was added. The temperature was controlled at 75℃ and the rotation speed at 3500rpm for 20min. Then, KQ-1000V ultrasonic equipment was used to ultrasonically treat it at a frequency of 30kHz and a power of 600W for 10min to obtain modified aluminum hypophosphite powder. This ensures that the coupling agent is uniformly coated on the surface of the flame retardant, improving its compatibility with polyester chips.

[0026] Melt blending: Using a DHG-9070A drying oven, polyester chips were dried at 130℃ for 4 hours to remove moisture and avoid air bubbles during spinning. Using an SHJ-35 twin-screw extruder, the dried polyester chips were added together with modified aluminum hypophosphite powder, antioxidant 1010, and calcium stearate. The screw speed was controlled at 220 rpm, and the temperature was gradually increased to 260℃, 275℃, and 285℃. After melt blending, the mixture was extruded and underwater pelletized to obtain flame retardant masterbatch with a pellet size of 3mm×3mm to ensure uniform dispersion of the flame retardant without agglomeration.

[0027] Melt spinning: Using an FA506 spinning machine, the flame retardant masterbatch is dried at 120℃ for 3 hours and then fed into the spinning machine. The spinning temperature is controlled at 280℃, the metering pump speed is 18 r / min, the spinneret orifice diameter is 0.3 mm, and the winding speed is 3500 m / min to produce nascent fibers. At the same time, the cooling air temperature is controlled at 25℃ and the air speed is controlled at 1.2 m / s to ensure that the nascent fibers are formed uniformly and without broken fibers.

[0028] Post-treatment: The nascent fibers are oiled with an oiling rate of 1.8% using a composite oiling agent; then, they are stretched at a stretching ratio of 3.5 times and a stretching temperature of 85℃; after stretching, they are heat-set at 150℃ for 15 minutes, with the setting tension controlled at 2.5 cN / dtex; finally, they are wound and separated, with the winding tension controlled at 2.0 cN / dtex, to obtain 30 tex flame-retardant polyester yarn.

[0029] When aluminum hypophosphite burns, it decomposes to produce substances such as phosphoric acid and polyphosphite. These substances can catalyze the dehydration of polyester molecular chains into carbon, forming a dense carbon layer that isolates oxygen and heat. At the same time, it releases inert gases to dilute flammable gases, achieving a flame-retardant effect. Silane coupling agents connect aluminum hypophosphite and polyester substrate through chemical bonds, effectively improving their compatibility and preventing flame retardant agglomeration that leads to a decrease in yarn mechanical properties. Antioxidants can prevent polyester from undergoing oxidative degradation during high-temperature spinning, while lubricants can improve spinning fluidity and reduce yarn breakage.

[0030] Example 2:

[0031] This embodiment uses a phosphorus-inorganic composite flame retardant system to reduce the amount of single phosphorus flame retardant added, improve the flame retardant efficiency and smoke suppression effect of the yarn, and optimize process parameters.

[0032] Raw material composition, expressed as a mass fraction:

[0033] The composition includes 75% polyester chips, 12% aluminum hypophosphite, 10% flame-retardant aluminum hydroxide, 2% silane coupling agent KH550, 0.6% antioxidant 1010, and 0.4% zinc stearate. This embodiment employs a phosphorus-inorganic composite flame-retardant system. The mass ratio of aluminum hypophosphite to flame-retardant aluminum hydroxide is 6:5. The silane coupling agent is modified separately. The raw material specifications are as follows: polyester chips: intrinsic viscosity 0.68 dL / g, melting point 255℃; aluminum hypophosphite: purity 99.5%, particle size 10μm; flame-retardant aluminum hydroxide: purity 99%, particle size 5μm, whiteness 92, moisture content 0.3%; silane coupling agent KH550: purity 98%; antioxidant 1010: purity 99%; zinc stearate: purity 98%.

[0034] Preparation process:

[0035] Flame retardant pretreatment: Using an SHR-10A high-speed mixer, aluminum hypophosphite and flame-retardant aluminum hydroxide were mixed evenly at a mass ratio of 6:5. Silane coupling agent KH550 was added, and the mixture was dispersed for 25 minutes at a controlled temperature of 80℃ and a rotation speed of 3800 rpm. Then, it was ultrasonically treated for 12 minutes using a KQ-1000V ultrasonic device at a frequency of 35kHz and a power of 700W to obtain a composite modified flame retardant powder. Flame-retardant aluminum hydroxide has a decomposition temperature of 190℃. When heated, it decomposes endothermically and releases water vapor, diluting flammable gases. Simultaneously, it generates alumina, forming a protective barrier, which synergistically enhances the flame retardant effect with aluminum hypophosphite.

[0036] Melt blending: The drying conditions of polyester chips were the same as in Example 1. Using an SHJ-35 twin-screw extruder, the dried polyester chips were added together with the composite modified flame retardant, antioxidant 1010, and zinc stearate. The screw speed was controlled at 230 rpm, and the temperature was gradually increased to 265°C, 280°C, and 290°C. After melt blending, the mixture was extruded and pelletized to obtain the composite flame retardant masterbatch.

[0037] Melt spinning: Using an FA506 spinning machine, the drying conditions of the flame retardant masterbatch were kept the same as in Example 1. The spinning temperature was controlled at 285℃, the metering pump speed at 19r / min, the spinneret orifice diameter at 0.3mm, the winding speed at 3800m / min, the cooling air temperature at 26℃, and the air velocity at 1.3m / s to obtain nascent fibers.

[0038] Post-treatment: The oiling rate was adjusted to 2.0%, and a composite oiling agent was used; the yarn was stretched at a stretching ratio of 3.8 times and a stretching temperature of 90℃; the heat setting temperature was 155℃ and the time was 18min, and the setting tension was controlled at 2.8cN / dtex; after winding and splitting, 30tex flame-retardant polyester yarn was obtained.

[0039] The catalytic char formation of aluminum hypophosphite, combined with the endothermic, dilution, and barrier effects of aluminum hydroxide, creates a synergistic effect. This not only reduces the amount of phosphorus-based flame retardant required but also significantly improves flame retardant efficiency and reduces smoke release during combustion. Aluminum hydroxide is an environmentally friendly halogen-free material. Its ultrafine particle size, after modification with a coupling agent, exhibits good compatibility with polyester substrates, avoiding the fiber embrittlement problem caused by traditional inorganic flame retardants.

[0040] Example 3:

[0041] This embodiment employs a silane-titanium ester coupling agent composite modification scheme, adding nano-silica as a synergist, while optimizing the spinning and finishing processes.

[0042] Raw material composition, expressed as a mass fraction:

[0043] The composition includes 72% polyester chips, 13% aluminum hypophosphite, 12% flame-retardant aluminum hydroxide, 1.2% silane coupling agent KH560, 1.0% titanate coupling agent NDZ311, 0.8% antioxidant 1010, 0.8% calcium stearate, and 0.2% nano-silica. This embodiment uses a silane-titanate coupling agent composite modification at a mass ratio of 1.2:1, with nano-silica added as a synergist to form a multi-component synergistic flame-retardant system. The raw material specifications are as follows: polyester chips with an intrinsic viscosity of 0.68 dL / g and a melting point of 255℃; aluminum hypophosphite with a purity of 99.5% and a particle size of 10 μm; flame-retardant aluminum hydroxide with a purity of 99% and a particle size of 5 μm; silane coupling agent KH560 and titanate coupling agent NDZ311 both with a purity of 98%; antioxidant 1010 with a purity of 99%; calcium stearate with a purity of 98%; and nano-silica with a purity of 99.8% and a particle size of 50 nm.

[0044] Preparation process:

[0045] Flame retardant pretreatment: Aluminum hypophosphite, flame-retardant aluminum hydroxide, and nano-silica were uniformly mixed using an SHR-10A high-speed mixer. Silane coupling agent KH560 and titanate coupling agent NDZ311 were added, and the mixture was dispersed for 30 minutes at a controlled temperature of 85℃ and a rotation speed of 4200 rpm. Then, it was ultrasonically treated for 15 minutes using a KQ-1000V ultrasonic device at a frequency of 40kHz and a power of 800W to obtain the composite modified flame retardant. The silane coupling agent mainly improves the compatibility between the flame retardant and the substrate, while the titanate coupling agent mainly improves the dispersibility of the flame retardant. Their synergistic effect effectively reduces the probability of flame retardant agglomeration. Nano-silica can fill the gaps in the char layer, improving the density of the char layer and the mechanical properties of the yarn.

[0046] Melt blending: Using a DHG-9070A drying oven, polyester chips were dried at 135℃ for 4.5h. Using an SHJ-35 twin-screw extruder, the dried polyester chips were added together with composite modified flame retardant, antioxidant, and calcium stearate. The screw speed was controlled at 240rpm, and the temperature was gradually increased to 270℃, 285℃, and 295℃. The mixture was then melt blended, extruded, and pelletized to obtain high-performance flame retardant masterbatch.

[0047] Melt spinning: Using an FA506 spinning machine, the flame retardant masterbatch was dried at 125℃ for 3.5h. The spinning temperature was controlled at 290℃, the metering pump speed at 20r / min, the spinneret orifice diameter at 0.3mm, the winding speed at 4200m / min, the cooling air temperature at 28℃, and the air velocity at 1.5m / s to obtain nascent fibers.

[0048] Post-treatment: Oiling rate 2.2%, using antistatic composite oil; segmented drafting method, total draft ratio 4.2, of which the first stage draft ratio 2.2 and temperature 85℃, the second stage draft ratio 1.9 and temperature 95℃; heat setting temperature 160℃ and time 20min, controlling the setting tension 3.0cN / dtex; using an HG-100 hot air dryer, post-treatment is carried out at 100℃ for 18min to obtain 30tex flame-retardant polyester yarn.

[0049] The synergistic effect of silane coupling agents and titanate coupling agents can significantly improve the bonding force and dispersibility between flame retardants and substrates; the synergistic effect of nano-silica and composite flame retardants not only enhances the flame retardant effect but also improves the mechanical properties of the yarn; segmented drafting and optimized finishing processes can effectively reduce internal fiber stress, improve yarn flexibility and washability, and prevent flame retardant from falling off after washing.

[0050] Example 4:

[0051] In this embodiment, red phosphorus coating is used to replace part of the aluminum hypophosphite to optimize the flame retardant system, and polyester-nylon composite chips are selected to expand the range of substrates and improve the flexibility and flame retardant durability of the yarn.

[0052] Raw material composition, expressed as a mass fraction:

[0053] Polyester-nylon composite chips 70%, aluminum hypophosphite 8%, coated red phosphorus 7%, flame-retardant aluminum hydroxide 12%, silane coupling agent KH560 1.5%, titanate coupling agent NDZ311 1.0%, antioxidant 1010 0.7%, zinc stearate 0.5%, nano silica 0.3%. In this embodiment, coated red phosphorus is used to replace part of the aluminum hypophosphite to form a ternary synergistic flame retardant system. The coupling agent mass ratio is 1.5:1. Polyester-nylon composite substrate is selected with a mass ratio of 7:3. The raw material specifications are as follows: polyester intrinsic viscosity 0.68 dL / g, nylon relative viscosity 2.4; aluminum hypophosphite purity 99.5%, particle size 10μm; coated red phosphorus purity 98%, particle size 15μm, inner layer nano-sized aluminum hydroxide coating thickness 0.5μm, outer layer thermosetting melamine resin coating thickness 1μm; flame retardant grade aluminum hydroxide purity 99%, particle size 5μm; coupling agent purity 98%; antioxidant 1010 purity 99%; zinc stearate purity 98%; nano silica purity 99.8%, particle size 50nm.

[0054] Preparation process:

[0055] Flame retardant pretreatment: Aluminum hypophosphite, coated red phosphorus, flame retardant aluminum hydroxide, and nano silica were mixed evenly using an SHR-10A high-speed mixer. The coated red phosphorus can reduce the phosphine release to 2.5 μg / g and will not break during high-temperature spinning. After adding a coupling agent, the mixture was dispersed at 90℃ and 4500 rpm for 35 min, and then ultrasonically treated for 18 min at 40 kHz and 900 W using a KQ-1000V ultrasonic device to obtain a high-efficiency composite modified flame retardant.

[0056] Melt blending: Using a DHG-9070A drying oven, polyester-nylon composite chips were dried at 140℃ for 5 hours. Using an SHJ-35 twin-screw extruder, the dried composite chips were added together with high-efficiency composite modified flame retardant, antioxidant, and zinc stearate. The screw speed was controlled at 250 rpm, and the temperature was gradually increased to 275℃, 290℃, and 300℃. The mixture was melt blended, extruded, and pelletized to obtain the composite substrate flame retardant masterbatch.

[0057] Melt spinning: Using an FA506 spinning machine, the flame retardant masterbatch was dried at 130℃ for 4 hours. The spinning temperature was controlled at 295℃, the metering pump speed at 21r / min, the spinneret orifice diameter at 0.3mm, the winding speed at 4500m / min, the cooling air temperature at 30℃, and the air velocity at 1.6m / s to obtain nascent fibers.

[0058] Post-treatment: Oiling rate 2.3%, using antistatic composite oil; segmented drafting method, total draft ratio 4.5, of which the first stage draft ratio 2.3 and temperature 88℃, the second stage draft ratio 1.96 and temperature 98℃; heat setting temperature 165℃ and time 22min, controlling the setting tension 3.2cN / dtex; using an HG-100 hot air dryer, finishing at 105℃ for 20min to obtain 30tex flame-retardant polyester-nylon composite yarn.

[0059] The coating of red phosphorus with aluminum hypophosphite and aluminum hydroxide forms a ternary synergistic flame retardant system, which can improve flame retardant efficiency and reduce the amount of flame retardant added. Its composite coating structure effectively solves the problems of easy oxidation and release of toxic gases of traditional red phosphorus. The polyester-nylon composite substrate takes into account both high strength and flexibility, which significantly expands the application scenarios of the yarn. The synergistic effect of the ternary flame retardant system and the composite substrate ensures that the yarn has excellent flame retardant performance, mechanical properties and washability.

[0060] Example 5:

[0061] This embodiment is based on embodiment 4, but with adjustments to the raw material ratio and process parameters.

[0062] Raw material composition, expressed as a mass fraction:

[0063] The composition includes 68% polyester-nylon composite chips, 7% aluminum hypophosphite, 8% coated red phosphorus, 14% flame-retardant aluminum hydroxide, 1.8% silane coupling agent KH560, 1.2% titanate coupling agent NDZ311, 0.6% antioxidant 1010, 0.4% calcium stearate, and 0.2% nano-silica. In this embodiment, the raw material ratio and process parameters are adjusted to suit the preparation of fine denier yarns. The coupling agent mass ratio is 1.5:1, the polyester-nylon mass ratio is 6:4, and the raw material specifications remain consistent with those in Example 4.

[0064] Preparation process:

[0065] Flame retardant pretreatment: Using an SHR-10A high-speed mixer, the flame retardant components were mixed evenly, a coupling agent was added, and the temperature was controlled at 95℃ and the rotation speed at 4500rpm for 40min. Then, the mixture was ultrasonically treated for 20min at a frequency of 40kHz and a power of 1000W using a KQ-1000V ultrasonic device to obtain the composite modified flame retardant.

[0066] Melt blending: Using a DHG-9070A drying oven, polyester-nylon composite chips were dried at 145℃ for 5.5h. Using an SHJ-35 twin-screw extruder, the dried composite chips were added together with composite modified flame retardant, antioxidant, and calcium stearate. The screw speed was controlled at 260rpm, and the temperature was gradually increased to 280℃, 295℃, and 305℃. The mixture was melt blended, extruded, and pelletized to obtain flame retardant masterbatch.

[0067] Melt spinning: Using an FA506 spinning machine, the flame retardant masterbatch was dried at 135℃ for 4.5h. The spinning temperature was controlled at 300℃, the metering pump speed at 22r / min, the spinneret orifice diameter at 0.25mm, the winding speed at 4500m / min, the cooling air temperature at 32℃, and the air velocity at 1.8m / s to obtain nascent fibers.

[0068] Post-treatment: Oiling rate 2.5%, using antistatic composite oil; segmented drafting method, total draft ratio 5.0, of which the first stage draft ratio 2.5 and temperature 90℃, the second stage draft ratio 2.0 and temperature 100℃; heat setting temperature 170℃ and time 25min, controlling the setting tension 3.5cN / dtex; using an HG-100 hot air dryer, finishing at 110℃ for 22min to obtain 25tex fine denier flame retardant polyester-nylon composite yarn.

[0069] By adjusting the raw material ratio and process parameters, it was verified that the present invention can produce high-performance flame-retardant yarns within a wide parameter range; the preparation of fine denier yarns further expands its application scenarios, and the ternary flame-retardant system ensures that even with a reduced diameter, it still possesses excellent flame-retardant and mechanical properties; increasing the heat setting temperature and time can improve the crystallinity and dimensional stability of the yarn, and enhance its temperature resistance and flame-retardant durability.

[0070] Comparative Example 1:

[0071] Raw material composition, expressed as a mass fraction:

[0072] The composition is 98.5% polyester chips, 0.8% antioxidant 1010, and 0.7% calcium stearate. The raw material specifications are consistent with those in Example 1.

[0073] Preparation process:

[0074] Except for the absence of flame retardants and coupling agents, the other process parameters are completely consistent with those in Example 1, and 30tex ordinary polyester yarn is obtained.

[0075] By comparing with the flame-retardant yarn of this invention, the core role of flame retardants in improving the flame-retardant performance of yarn is clearly defined.

[0076] Comparative Example 2:

[0077] Raw material composition, expressed as a mass fraction:

[0078] The raw materials consist of 75% polyester chips, 22% flame-retardant aluminum hydroxide, 0.8% antioxidant 1010, and 2.2% calcium stearate. The raw material specifications are consistent with those in Example 2.

[0079] Preparation process:

[0080] Except for the absence of aluminum hypophosphite and coupling agent, and the addition of only unmodified flame-retardant aluminum hydroxide in the same amount as the total amount of composite flame retardant in Example 2, the other process parameters are completely the same as in Example 2, and 30tex flame-retardant polyester yarn is obtained.

[0081] Comparing the performance differences between a single unmodified inorganic flame retardant system and the composite modified flame retardant system of this invention highlights the advantages of the composite flame retardant system and coupling agent modification process of this invention.

[0082] Comparative Example 3:

[0083] The raw material composition is completely consistent with that of Example 3.

[0084] Preparation process:

[0085] Except for replacing the composite coupling agent with a single silane coupling agent KH560 and adding it at a rate of 2.2%, the other process parameters were completely consistent with those in Example 3, and 30tex flame-retardant polyester yarn was obtained.

[0086] Comparing the effects of single coupling agent modification and composite modification with coupling agents of the present invention highlights the advantages of the composite modification process of the present invention.

[0087] Comparative Example 4:

[0088] Raw material composition, expressed as a mass fraction:

[0089] The composition consists of 72% polyester chips, 15% aluminum hypophosphite, 10% flame-retardant aluminum hydroxide, 2.2% silane coupling agent KH560, 0.8% antioxidant 1010, and 0.8% calcium stearate. The raw material specifications are consistent with those in Example 3.

[0090] Preparation process:

[0091] Except for the absence of nano-silica and the lack of synergistic ratio between aluminum hypophosphite and aluminum hydroxide, the other process parameters were completely consistent with those in Example 3, and 30tex flame-retardant polyester yarn was obtained.

[0092] The difference in performance between the simple composite flame retardant system and the quaternary synergistic composite flame retardant system of the present invention highlights the advantages of the synergistic design of the present invention.

[0093] Comparative Example 5:

[0094] The raw material composition is completely consistent with that of Example 3.

[0095] Preparation process:

[0096] Except for the melt spinning temperature of 240℃, the draw ratio of 2.0, and the heat setting temperature of 110℃, the other process parameters are completely consistent with those in Example 3, and 30tex flame-retardant polyester yarn is obtained.

[0097] This verifies the rationality of the protection scope of the process parameters in this invention and highlights the important impact of process parameter optimization on yarn performance.

[0098] Comparative Example 6:

[0099] Raw material composition, expressed as a mass fraction:

[0100] The composition consists of 78% polyester chips, 18% decabromodiphenyl ether, 0.8% antioxidant 1010, and 3.2% calcium stearate. The raw material specifications are consistent with those in Example 1.

[0101] Preparation process:

[0102] Except for using decabromodiphenyl ether as a flame retardant and not adding a coupling agent, the other process parameters are completely consistent with those in Example 1, and 30tex brominated flame-retardant polyester yarn is obtained.

[0103] By comparing the performance differences between the halogen-free composite flame retardant system of this invention and the traditional bromine-based flame retardant system, the environmental advantages of this invention are highlighted.

[0104] Performance testing and results analysis:

[0105] Test items and test standards:

[0106] (1) Limiting oxygen index: Tested according to GB / T5454-1997 "Test for flammability of textiles by oxygen index method". The test environment temperature is 23℃ and the humidity is 50%RH. Five samples are tested in each group and the average value is taken. Among them, the limiting oxygen index ≥28% is flame retardant, ≥32% is highly flame retardant, and ≥40% is quasi-non-flammable.

[0107] (2) Vertical burning performance: Tested according to GB / T5455-2014 "Vertical Method for Testing Burning Performance of Textiles", with a sample size of 300mm×80mm, an ignition time of 3s, and recording the afterflame time, smoldering time, and burn length. Five samples were tested in each group, and the average value was taken. The burning rating is divided into four levels: A, B1, B2, and C. The target rating of this invention is B1 level and above.

[0108] (3) Mechanical properties: Tested according to GB / T14344-2008 "Test Method for Tensile Properties of Chemical Fiber Filaments", with a test speed of 50 mm / min and a clamping distance of 250 mm. Five samples were tested in each group, and the average value was taken. The test items were breaking strength and breaking elongation.

[0109] (4) Washing durability: 50 washes were performed according to GB / T8629-2017 "Home washing and drying procedures for textile testing". The limiting oxygen index and vertical burning performance were tested again after washing. The washing conditions were water temperature 40℃, washing time 30min and drying temperature 80℃.

[0110] (5) Smoke density test: Test according to GB / T8323.2-2008 Plastics Smoke Generation Part 2 Determination of Smoke Density by Single Chamber Method, and record the maximum smoke density within 300s of combustion; the environmentally friendly halogen-free requirement is that no toxic or harmful gases are released during combustion and that it complies with the EU REACH standard.

[0111] (6) Spinning performance: Record the breakage rate during the spinning process to evaluate the dispersibility and process stability of the flame retardant.

[0112] The test results are shown in Table 1 below:

[0113] Sample number Limiting oxygen index % Vertical combustion performance (afterflame / smoldering time in seconds, burn-off length in mm, rating) Fracture strength cN / dtex Elongation at break % Limiting oxygen index % after 50 washes Maximum smoke density Broken wire rate per ton Environmental protection Example 1 33.2 2.1 / 8.5，28，B1 3.8 35.6 31.8 270 0.4 Halogen-free and low-toxicity, compliant with REACH Example 2 35.8 1.5 / 7.2，22，B1 4.1 37.2 34.5 245 0.3 Halogen-free and low-toxicity, compliant with REACH Example 3 38.5 1.0 / 5.8，18，B1 4.5 39.5 37.2 220 0.2 Halogen-free and low-toxicity, compliant with REACH Example 4 40.2 0.8 / 4.5，15，A 4.8 41.2 38.9 205 0.15 Halogen-free and low-toxicity, compliant with REACH Example 5 41.5 0.6 / 3.8，12，A 5.0 42.5 40.1 190 0.1 Halogen-free and low-toxicity, compliant with REACH Comparative Example 1 21.5 18.6 / 25.3，120，C 5.2 43.8 21.3 480 0.08 Halogen-free, REACH compliant Comparative Example 2 29.8 4.2 / 12.6，45，B2 3.2 32.5 27.6 310 0.8 Halogen-free and low-toxicity, compliant with REACH Comparative Example 3 35.2 1.8 / 8.3，25，B1 3.9 36.8 33.1 255 0.45 Halogen-free and low-toxicity, compliant with REACH Comparative Example 4 34.7 2.0 / 9.1，27，B1 3.8 35.9 32.5 260 0.5 Halogen-free and low-toxicity, compliant with REACH Comparative Example 5 32.1 2.5 / 10.2，32，B1 3.5 34.8 30.2 280 0.6 Halogen-free and low-toxicity, compliant with REACH Comparative Example 6 33.0 2.3 / 9.0，30，B1 3.7 34.5 30.5 380 0.6 Bromine is toxic and does not comply with REACH.

[0114] Results analysis:

[0115] Based on the performance test data of all embodiments and comparative examples, it can be seen that the flame-retardant yarn prepared by the present invention has significantly better overall performance than existing technologies and parameter deviation schemes. Examples 1 to 5 show a progressive performance improvement, with Example 5 exhibiting the best performance: a limiting oxygen index of 41.5%, a vertical flammability rating of A, a breaking strength of 5.0 cN / dtex, an elongation at break of 42.5%, a limiting oxygen index remaining at 40.1% after 50 washes, a maximum smoke density of 190, and a breakage rate of 0.1 times / ton. Furthermore, it is halogen-free and low in toxicity, complying with REACH standards. This fully demonstrates the technical advantages of the present invention's multi-component synergistic flame-retardant system, coupling agent composite modification, and optimized process parameters.

[0116] Comparative Example 1, which was a blank control, had no flame retardant, a limiting oxygen index of only 21.5%, and a vertical flammability rating of C, failing to meet flame retardant performance standards. This clearly demonstrates the core role of flame retardants in yarn flame retardant performance. Comparative Example 2 used a single unmodified inorganic flame retardant system, with a limiting oxygen index of 29.8%, a breaking strength of 3.2 cN / dtex, and a breakage rate of 0.8 times / ton. Its performance was far lower than that of Example 2, which used a composite modified flame retardant system, highlighting the necessity of composite flame retardant systems and coupling agent modification. Comparative Example 3 used a single coupling agent modification. Compared to Example 3, its limiting oxygen index and breaking strength both decreased, while the breakage rate increased to 0. The 45 times / ton indicates that the synergistic effect of the silane-titanium ester coupling agent composite modification is better; Comparative Example 4 did not add nano-silica and had no synergistic ratio design, and its performance was significantly reduced compared with Example 3, verifying the synergistic effect of nano-silica and the importance of the synergistic ratio; Comparative Example 5's process parameters deviated from the design range of this invention, and all performances declined, proving the rationality and optimization value of the process parameters of this invention; Comparative Example 6 used a traditional bromine-based flame retardant system, which has certain flame retardant properties, but releases toxic gases during combustion, does not meet environmental protection standards, and has a smoke density as high as 380, and its overall performance is not as good as the halogen-free composite flame retardant system of this invention.

[0117] This invention achieves a synergistic improvement in flame retardant performance, mechanical properties, water washability, processing stability, and environmental friendliness through reasonable raw material ratio design, coupling agent composite modification, and process optimization.

[0118] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A flame-retardant yarn, characterized in that, The raw materials, by mass fraction, include: 78% polyester chips, 18% aluminum hypophosphite, 2.5% silane coupling agent KH550, 0.8% antioxidant 1010, and 0.7% calcium stearate.

2. The flame-retardant yarn according to claim 1, characterized in that, The polyester chips are replaced with 75%, the aluminum hypophosphite is 12%, and flame-retardant aluminum hydroxide is added at 10%. The mass ratio of aluminum hypophosphite to flame-retardant aluminum hydroxide is 6:

5. The silane coupling agent KH550 is 2%, the antioxidant 1010 is 0.6%, and calcium stearate is replaced with zinc stearate at 0.4%.

3. The flame-retardant yarn according to claim 2, characterized in that, The polyester chips comprise 72%, the aluminum hypophosphite comprises 13%, the flame-retardant aluminum hydroxide comprises 12%, the silane coupling agent KH550 is replaced with silane coupling agent KH560 1.2%, the titanate coupling agent NDZ311 1.0% is also added, the zinc stearate is replaced with calcium stearate 0.8%, and nano silica 0.2% is also added.

4. The flame-retardant yarn according to claim 3, characterized in that, The polyester chips are replaced with 70% polyester-nylon composite chips, the aluminum hypophosphite is 8%, coated red phosphorus is added 7%, the flame-retardant aluminum hydroxide is 12%, the silane coupling agent KH560 is 1.5%, the titanate coupling agent NDZ311 is 1.0%, the antioxidant 1010 is 0.7%, the calcium stearate is replaced with 0.5% zinc stearate, and the nano silica is 0.3%.

5. The flame-retardant yarn according to claim 4, characterized in that, The polyester-nylon composite chips comprise 68%, the aluminum hypophosphite comprises 7%, the coated red phosphorus comprises 8%, the flame-retardant aluminum hydroxide comprises 14%, the silane coupling agent KH560 comprises 1.8%, the titanate coupling agent NDZ311 comprises 1.2%, the antioxidant 1010 comprises 0.6%, zinc stearate is replaced with calcium stearate 0.4%, and nano silica comprises 0.2%.

6. A process for preparing flame-retardant yarn according to any one of claims 1 to 5, characterized in that, The process includes the following steps in sequence: flame retardant pretreatment, melt blending, melt spinning, and post-treatment. The flame retardant pretreatment involves mixing the flame retardant component with a coupling agent, followed by high-speed dispersion and ultrasonic treatment to obtain a modified flame retardant. The melt blending process involves drying the chips and then adding them to a twin-screw extruder along with the modified flame retardant, antioxidant 1010, and stearate. The resulting melt blended chips are then extruded and pelletized to obtain flame retardant masterbatch. The melt spinning process involves drying the flame retardant masterbatch and then spinning it to obtain nascent fibers. The post-treatment process involves sequentially oiling, stretching, heat setting, and winding the nascent fibers to obtain flame retardant yarn.

7. The preparation process according to claim 6, characterized in that, The high-speed dispersion temperature for flame retardant pretreatment is 75℃-95℃, the rotation speed is 3500rpm-4500rpm, and the dispersion time is 20min-40min; the ultrasonic treatment frequency is 30kHz-40kHz, the power is 600W-1000W, and the treatment time is 10min-20min.

8. The preparation process according to claim 6, characterized in that, The drying temperature of the chips in the melt blending process is 130℃-145℃, and the drying time is 4h-5.5h; the twin-screw extruder speed is 220rpm-260rpm, and the gradient temperature is 260℃-305℃.

9. The preparation process according to claim 6, characterized in that, The drying temperature of the flame retardant masterbatch in melt spinning is 120℃-135℃, and the drying time is 3h-4.5h; the spinning temperature is 280℃-300℃, and the winding speed is 3500m / min-4500m / min.

10. The preparation process according to claim 6, characterized in that, In the post-treatment, the oiling rate is 1.8%-2.5%, the draw ratio is 3.5-5.0 times, the heat setting temperature is 150℃-170℃, and the heat setting time is 15min-25min.