Process for the preparation of a flame and melt-drip resistant fibre

Abstract

The application discloses a kind of preparation process of flame-retardant anti-dripping fiber, comprising the following steps: raw material mixing, efficient filtration, melt extrusion, step-by-step cooling solidification, post-processing, and flame-retardant anti-dripping fiber is prepared.The application accurately controls the proportion of flame retardant and mixing process in the raw material mixing stage, ensures that the flame retardant is uniformly dispersed in the polymer matrix, and provides efficient flame-retardant performance for the fiber;Efficient filtration link uses full-automatic replacement filter screen device to remove impurities regularly, ensures that the melt is pure and uniform;Melt extrusion and gradient cooling solidification process effectively reduces the internal stress and defects of the fiber, improves the fiber forming quality;Drafting and heat setting treatment in the post-processing stage further optimizes the fiber structure and enhances the mechanical properties.The flame-retardant anti-dripping fiber finally prepared has excellent flame-retardant anti-dripping performance and stable physical and mechanical properties, and the preparation method realizes the significant improvement of the performance of flame-retardant anti-dripping fiber through multi-link synergistic optimization.

Description

Technical Field

[0001] This invention relates to the field of flame-retardant and anti-dripping fibers, and more specifically to a preparation process for flame-retardant and anti-dripping fibers. Background Technology

[0002] Flame-retardant and anti-dripping fibers have wide applications in aerospace, electronics, transportation, and other fields. They can effectively prevent the spread of flames and suppress the generation of molten droplets, which is crucial for improving the safety of materials. In the existing technology, the preparation process of flame-retardant and anti-dripping fibers usually involves mixing halogen-based, phosphorus-based, and nitrogen-based flame retardants with a fiber polymer matrix, followed by spinning, post-treatment, and other steps to obtain the finished product.

[0003] However, traditional manufacturing processes have many shortcomings. The lack of effective melt filtration before spinning means that impurities and unmelted particles remaining in the polymer mixture can cause spinneret blockage and fiber breakage during spinning, affecting the fiber's surface quality and mechanical properties. While some processes use filters, these often become clogged, preventing the melt from passing through the effective filtration area and leading to product defects (such as unmelted particles in fiber products). Conventional cooling methods are mostly single-temperature cooling, failing to achieve gradient cooling of the fiber. This causes internal stress due to temperature differences during curing, resulting in deformation, cracking, and other defects, which in turn affect the fiber's flame-retardant and anti-dripping properties and dimensional stability. Furthermore, traditional processes require manual, periodic filter replacement, which is cumbersome, easily interrupts production, and reduces efficiency.

[0004] Therefore, there is an urgent need for a flame-retardant and anti-dripping fiber preparation process that enables precise melt filtration, fiber gradient cooling, and continuous production to overcome the shortcomings of existing technologies and improve product quality and production efficiency. Summary of the Invention

[0005] The purpose of this invention is to solve the problems in the background art and provide a preparation process for flame-retardant and anti-dripping fibers.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0007] A process for preparing flame-retardant and anti-dripping fibers includes the following steps:

[0008] S1, Raw material mixing: Dry the PET resin at 120-130℃ for 5-7 hours to remove moisture; weigh all raw materials according to the formula ratio, place them in a high-speed mixer, and mix at 1000 rpm for 12 minutes to ensure that the materials are fully and evenly mixed.

[0009] S2, high-efficiency filtration: The uniformly mixed polymer mixture is fed into the screw extruder and heated to 220-320℃ to fully melt it. After extrusion, it is immediately connected to a fully automatic filter screen replacement device for filtration. By replacing the filter screen, impurities are efficiently removed, filtration is ensured to be continuous, and melt uniformity is improved.

[0010] S3, melt extrusion, which involves extruding the polymer melt after high-efficiency filtration through a spinneret to form a melt stream;

[0011] S4, graded cooling and solidification: the melt stream is cooled in a gradient by a slow cooling device to promote uniform fiber solidification, reduce stress and defects, improve flame retardant and anti-dripping performance stability, and form nascent fibers.

[0012] S5, Post-processing: The nascent fibers are stretched and heat-set. The stretching ratio is 2-5 times, the stretching temperature is 80-120℃, and the heat-setting temperature is 180-220℃ for 5-15 minutes to obtain flame-retardant and anti-dripping fibers.

[0013] This invention utilizes a fully automated filter replacement device to periodically remove impurities during the high-efficiency filtration stage, ensuring the purity and uniformity of the melt. The melt extrusion and gradient cooling solidification processes effectively reduce internal stress and defects within the fiber, improving fiber forming quality. The stretching and heat-setting treatments in the post-processing stage further optimize the fiber structure and enhance mechanical properties. The resulting flame-retardant and anti-drip fiber possesses both excellent flame-retardant and anti-drip properties and stable physical and mechanical properties. This preparation method achieves a significant improvement in the performance of flame-retardant and anti-drip fibers through multi-stage synergistic optimization.

[0014] Preferably, the fully automatic filter replacement device includes a fixed plate, a roller, a pressing and clamping mechanism, a pulling mechanism, and a laser cutting mechanism. The fixed plate has a filter guide groove from left to right, and a flow guide hole is formed at the top of the fixed plate. The roller is located at the inlet of the filter guide groove, the pressing and clamping mechanism is located at the outlet of the filter guide groove, the pulling mechanism is located behind the pressing and clamping mechanism, and the laser cutting mechanism is located above the pressing and clamping mechanism for cutting the filter.

[0015] It is also equipped with a differential pressure sensor with two pressure ports, which are connected to the filter inlet and outlet respectively, to measure the pressure difference between the upstream and downstream of the filter. When the pressure difference rises above the set threshold, it indicates that the filter is clogged.

[0016] This invention uses a roller to wind a soft filter screen onto a spool. The soft filter screen passes through a filter screen guide groove and is fixed by a pressing and clamping mechanism. Molten material flows into the soft filter screen through a guide hole. When a differential pressure sensor detects filter screen blockage, it automatically triggers a screen replacement. A pulling mechanism pulls out the soft filter screen located in the guide hole, and a new filter screen is pulled out from the roller, passes through the filter screen guide groove, and is fixed on the pressing and clamping mechanism. The blocked part of the filter screen is cut by a laser cutting mechanism, thus completing the automatic and rapid filter screen replacement without machine downtime. This enables continuous production, precise filtration, and reduced manual intervention, avoiding unfiltered molten material entering the product due to delays caused by manual screen replacement. At the same time, in the production of flame-retardant and anti-dripping fibers, it can effectively filter flame retardant agglomerates, prevent the appearance of "hard spots" on the fiber surface or the formation of voids inside, improve fiber smoothness and mechanical properties, and make impurity filtration more precise, thereby improving product purity.

[0017] Preferably, the pressing and clamping mechanism includes a lower pressing block, an upper pressing block, a connecting plate, a pressing electric push rod, and a fixing frame. The fixing frame is fixed at the outlet of the filter screen guide groove. Several lower pressing blocks are linearly arrayed on the fixing frame and located below the filter screen guide groove. A clamping port for easy clamping is provided between two adjacent lower pressing blocks. An upper pressing block is provided above each lower pressing block. The upper pressing block is fixed on the connecting plate. The push rod end of the pressing electric push rod is fixedly connected to the connecting plate. The motor end of the pressing electric push rod is fixed on the fixing frame.

[0018] The present invention can clamp the filter screen by means of the lower pressure block and the upper pressure block, and the clamping opening between adjacent lower pressure blocks facilitates the clamping operation of the pull-out mechanism.

[0019] Preferably, the pull-out mechanism includes a linear slide rail, a slider, a connecting strip, and a gripper structure. The two linear slide rails are located on both sides of the lower pressure block and are fixed on the fixed frame. The slider is slidably located on the linear slide rail. The connecting strip is located between the two sliders. Several gripper structures are fixed on the connecting strip, and each gripper structure corresponds to a gripping opening.

[0020] This invention uses a slider that moves on a linear slide rail to move a gripper structure close to the gripping opening to grip the filter screen. After gripping, the filter screen can be pulled out, thus achieving automatic pulling.

[0021] Preferably, the gripper structure includes an upper gripper, a lower gripper, a slide rod, a slide rod electric push rod, and a fixing block. The fixing block is fixed to the connecting strip. A sliding groove is formed in the fixing block. The slide rod is disposed in the sliding groove. The slide rod electric push rod is disposed in the sliding groove, and its push rod end is fixed to the end of the slide rod. An extension plate is provided at the front end of the fixing block. A first mounting plate is provided at the rear end of the lower gripper. Two second mounting plates are provided at the rear end of the upper gripper. The slide rod is hinged to the first mounting plate. The first mounting plate is hinged to the second mounting plates. The extension plate is hinged to the second mounting plates.

[0022] This invention uses the reciprocating motion of the electric push rod to drive the slide rod to reciprocate within the slide groove, thereby driving the opening and closing of the upper and lower grippers.

[0023] Preferably, a pressure ring is provided above the flow guide hole of the fixed plate, and a filter screen is left between the bottom of the pressure ring and the fixed plate. A tightening rod is provided at the top of the pressure ring, and an electric push rod for the pressure ring is provided at the top of the tightening rod. A limiting groove is opened at the position of the top of the pressure ring corresponding to the position of the tightening rod. A magnet is provided in the limiting groove, and the tightening rod can be made of metal.

[0024] This invention uses an electric push rod to drive the pressure ring to press the filter screen, so that the melt can only flow through the guide hole. When the filter screen needs to be replaced, the electric push rod drives the pressure ring to rise, releasing the pressure on the filter screen and allowing the filter screen to move freely.

[0025] This invention uses a magnet to make the pressure ring and the clamping rod detachably connected, so that the pressure ring can be replaced with different sizes as needed.

[0026] Preferably, the inner sides of both the upper and lower grippers are provided with rubber pads to enhance the clamping force.

[0027] The laser cutting mechanism includes a slide rail and a laser head, which allows the slide rail to move the laser head to complete the cutting, so that the filter screen portion that exits from the guide hole can be removed for easy collection later.

[0028] Preferably, the slow cooling device is a cooling coil, with a water inlet at the bottom and a water outlet at the top. The outer wall of the cooling coil is provided with a heat dissipation pipe, and the heat dissipation pipe is provided with multiple heat dissipation fins.

[0029] In this invention, the coolant enters from the bottom inlet and flows upward along the cooling coil, resulting in a higher temperature in the upper layer of the cooling coil compared to the lower layer. This causes the cooling coil to absorb heat as the molten stream passes through, leading to a slow cooling of the molten stream. From a dispersibility perspective, this prolongs the liquid state time of the melt, promoting uniform dispersion of the flame retardant, reducing agglomeration, enhancing the reaction of the phosphorus-nitrogen synergistic flame retardant system, and optimizing the char layer structure. In terms of crystallization control, it facilitates the formation of a stable α-crystal form, increases crystallinity, and reduces crystal defects. Regarding the fiber structure, it can reduce the thickness of the outer layer, balance the performance of the core and outer layer, and reduce the risk of delamination, breakage, and dripping caused by structural differences. Furthermore, it can enhance the interfacial bonding force between the flame retardant and the matrix, anchoring the melt.

[0030] This invention accelerates cooling efficiency through heat pipes and heat sinks.

[0031] Preferably, the outlet is connected to a radiator, and the outlet of the cooler is connected to the inlet of the cooling coil, so that the coolant can be recycled.

[0032] In summary, the beneficial effects of this invention are as follows:

[0033] 1. This invention utilizes a fully automated filter replacement device to periodically remove impurities during the high-efficiency filtration stage, ensuring the purity and uniformity of the melt. The melt extrusion and gradient cooling solidification process effectively reduces internal stress and defects in the fiber, improving fiber forming quality. The stretching and heat setting treatments in the post-processing stage further optimize the fiber structure and enhance mechanical properties. The resulting flame-retardant and anti-dripping fiber possesses both excellent flame-retardant and anti-dripping properties and stable physical and mechanical properties. This preparation method achieves a significant improvement in the performance of flame-retardant and anti-dripping fibers through multi-stage synergistic optimization.

[0034] 2. This invention uses a roller to wind a soft filter screen onto a roller. The soft filter screen passes through a filter screen guide groove from a fixed plate and is fixed by a pressing and clamping mechanism. Melt flows into the soft filter screen through a guide hole. When a differential pressure sensor detects filter screen blockage, it automatically triggers a screen replacement. The soft filter screen located in the guide hole is pulled out by a pulling mechanism, and a new filter screen is pulled out from the roller, passes through the filter screen guide groove, and is fixed on the pressing and clamping mechanism. The blocked part of the filter screen is cut by a laser cutting mechanism, thereby completing the automatic and rapid replacement of the filter screen without stopping the machine. This enables continuous production, precise filtration, and reduced manual intervention. It avoids unfiltered melt from entering the product due to delays caused by manual screen replacement. In the production of flame-retardant and anti-dripping fibers, it can effectively filter flame retardant agglomerates, prevent the appearance of "hard spots" on the fiber surface or the formation of voids inside, improve fiber smoothness and mechanical properties, filter impurities more accurately, and improve product purity.

[0035] 3. In this invention, the coolant enters from the bottom inlet and flows upward along the cooling coil, making the temperature of the upper layer of the cooling coil higher than that of the lower layer. As the melt stream passes through the cooling coil, the cooling coil absorbs heat, causing the melt stream to cool down slowly. From a dispersibility perspective, this prolongs the melt liquid state time, promotes uniform dispersion of the flame retardant, reduces agglomeration, enhances the reaction of the phosphorus-nitrogen synergistic flame retardant system, and optimizes the char layer structure. In terms of crystallization control, it is beneficial to generate a stable α crystal form, improves crystallinity, reduces crystal defects, can reduce the thickness of the skin layer, balances the skin-core performance, and reduces the risk of delamination and droplet breakage due to structural differences. It can also enhance the interfacial bonding force between the flame retardant and the matrix, anchoring the melt. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the fully automatic filter replacement device of the present invention;

[0037] Figure 2 This is a schematic diagram of the pressing and clamping mechanism and the pulling mechanism of the present invention;

[0038] Figure 3 This is a schematic diagram of the fixing plate of the present invention;

[0039] Figure 4 This is a cross-sectional schematic diagram of the fixing plate of the present invention;

[0040] Figure 5 This is the present invention. Figure 4 An enlarged view of point A;

[0041] Figure 6 This is a schematic diagram of the gripper structure of the present invention;

[0042] Figure 7 This is a cross-sectional schematic diagram of the gripper structure of the present invention;

[0043] Figure 8 This is a schematic diagram of the gripper structure of the present invention without the upper gripper and the fixing block;

[0044] Figure 9 This is a schematic diagram of the gripper of the present invention;

[0045] Figure 10 This is a schematic diagram of the slow cooling device of the present invention;

[0046] Figure 11 This is a schematic diagram of the cooling coil of the present invention.

[0047] 1. Fully automatic filter replacement device; 11. Fixing plate; 12. Roller; 13. Pressing and clamping mechanism; 14. Pull-out mechanism; 15. Laser cutting mechanism; 110. Filter screen guide groove; 111. Guide hole; 131. Lower pressure block; 132. Upper pressure block; 133. Connecting plate; 134. Pressing electric push rod; 135. Fixing frame; 136. Clamping port; 141. Linear slide rail; 142. Slider; 143. Connecting bar; 16. Claw structure; 161. Upper claw; 162. 163. Lower clamping jaw; 164. Slide rod; 165. Slide rod electric push rod; 166. Fixing block; 167. Extension plate; 168. First mounting plate; 169. Second mounting plate; 17. Pressure ring; 175. Filter screen passage space; 171. Tightening rod; 172. Pressure ring electric push rod; 173. Limiting groove; 174. Magnet; 160. Rubber gasket; 2. Slow cooling device; 21. Cooling coil; 210. Water inlet; 211. Water outlet; 212. Heat dissipation pipe; 213. Heat dissipation fins. Detailed Implementation

[0048] The following specific embodiments are merely illustrative of the present invention and are not intended to limit the invention. Those skilled in the art can make modifications to these embodiments without contributing any inventive step after reading this specification, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

[0049] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0050] Example 1

[0051] A process for preparing flame-retardant and anti-dripping fibers includes the following steps:

[0052] S1, Raw material mixing: Dry the PET resin at 120 ℃ for 5 hours to remove moisture; weigh all raw materials according to the formula ratio, place them in a high-speed mixer, and mix at 1000 rpm for 12 minutes to ensure that the materials are fully and evenly mixed.

[0053] S2, High-efficiency filtration: The uniformly mixed polymer mixture is fed into the screw extruder, heated and melted, then extruded and immediately fed into the system. A fully automatic filter replacement device 1 performs filtration, efficiently removing impurities, ensuring continuous filtration, and improving melt uniformity by replacing the filter screen.

[0054] S3, melt extrusion, which involves extruding the polymer melt after high-efficiency filtration through a spinneret to form a melt stream;

[0055] S4, step-by-step cooling and solidification: the melt stream is cooled in a gradient by the slow cooling device 2 to promote uniform fiber solidification, reduce stress and defects, improve flame retardant and anti-dripping performance stability, and form nascent fibers.

[0056] S5, Post-processing: The nascent fibers are stretched and heat-set. The stretching ratio is 2 times and the stretching temperature is 80 ℃. The heat-setting temperature is 180 ℃ and the time is 5 minutes to obtain flame-retardant and anti-dripping fibers.

[0057] Flame-retardant and anti-dripping PET balanced formulation

[0058]

[0059] like Figure 1 As shown, the fully automatic filter replacement device 1 includes a fixed plate 11, a roller 12, a pressing and clamping mechanism 13, a pulling mechanism 14, and a laser cutting mechanism 15. The fixed plate 11 has a filter guide groove 110 from left to right, and a guide hole 111 is provided on the top of the fixed plate 11. The roller 12 is located in the inlet direction of the filter guide groove 110, the pressing and clamping mechanism 13 is located in the outlet direction of the filter guide groove 110, the pulling mechanism 14 is located behind the pressing and clamping mechanism 13, and the laser cutting mechanism 15 is located above the pressing and clamping mechanism 13 for cutting the filter.

[0060] like Figures 2-9As shown, the pressing and clamping mechanism 13 includes a lower pressing block 131, an upper pressing block 132, a connecting plate 133, a pressing electric push rod 134, and a fixing frame 135. The fixing frame 135 is fixed at the outlet of the filter screen guide groove 110. Several lower pressing blocks 131 are linearly arrayed on the fixing frame 135 and located below the filter screen guide groove 110. A clamping port 136 is provided between two adjacent lower pressing blocks 131 for easy clamping. Each lower pressing block 131 is provided with an upper pressing block 132 above it. The upper pressing block 132 is fixed on the connecting plate 133. The push rod end of the pressing electric push rod 134 is connected to the connecting plate 133. The motor end of the pressing electric push rod 134 is fixed to the fixing frame 135. The pull-out mechanism 14 includes a linear slide rail 141, a slider 142, a connecting bar 143, and a gripper structure 16. Two linear slide rails 141 are located on both sides of the lower pressing block 131 and are fixed to the fixing frame 135. The slider 142 slides on the linear slide rail 141. The connecting bar 143 is located between the two sliders 142. Several gripper structures 16 are fixed to the connecting bar 143. Each gripper structure 16 corresponds to a gripping opening 136. Each gripper structure 16 includes an upper gripper 161 and a lower gripper 162. 2. A sliding rod 163, a sliding rod electric push rod 164, and a fixing block 165. The fixing block 165 is fixed to the connecting strip 143. A sliding groove 166 is formed in the fixing block 165. The sliding rod 163 is disposed in the sliding groove 166. The sliding rod electric push rod 164 is disposed in the sliding groove 166, and its push rod end is fixed to the end of the sliding rod 163. An extension plate 167 is provided at the front end of the fixing block 165. A first mounting plate 168 is provided at the rear end of the lower gripper 162. Two second mounting plates 169 are provided at the rear end of the upper gripper 161. The sliding rod 163 is hinged to the first mounting plate 168. 168 is hinged to the second mounting plate 169, the extension plate 167 is hinged to the second mounting plate 169, a pressure ring 17 is provided above the guide hole 111 of the fixed plate 11, a filter screen passage space 175 is left between the bottom of the pressure ring 17 and the fixed plate 11, a tightening rod 171 is provided at the top of the pressure ring 17, a pressure ring electric push rod 172 is provided at the top of the tightening rod 171, a limiting groove 173 is opened at the position of the pressure ring 17 corresponding to the tightening rod 171, a magnet 174 is provided in the limiting groove 173, and rubber pads 160 are provided on the inner sides of the upper jaw 161 and the lower jaw 162.

[0061] like Figures 10-11As shown, the slow cooling device 2 is a cooling coil 21. The bottom of the cooling coil 21 is provided with a water inlet 210, the top of the cooling coil 21 is provided with a water outlet 211, the outer wall of the cooling coil 21 is provided with a heat dissipation pipe 212, the heat dissipation pipe 212 is provided with a plurality of heat dissipation fins 213, the water outlet 211 is connected to a radiator, and the outlet of the radiator is connected to the water inlet 210 of the cooling coil 21.

[0062] Working principle: such as Figure 1-11 As shown, the working principle is as follows: After the raw materials are mixed, they are fed into a screw extruder for heating and melting. The molten mixture is extruded through the extruder and then filtered efficiently through the guide holes 111 of the fully automatic filter screen replacement filter device 1. The polymer melt after high-efficiency filtration is extruded through a spinneret to form a melt stream. The melt stream passes through a cooling coil 21, which slowly cools the melt stream, reduces stress and defects, and improves the stability of flame retardant and anti-dripping properties, forming nascent fibers. The nascent fibers are then stretched and heat-set. The stretching ratio is 2-5 times, the stretching temperature is 80-120℃, and the heat-setting temperature is 180-220℃ for 5-15 minutes to obtain flame retardant and anti-dripping fibers.

[0063] During the entire operation, when the differential pressure rises above the set threshold, the automatic screen replacement is triggered. The electric push rod 164 moves forward, driving the slide rod 163 forward, thus opening the upper gripper 161 and lower gripper 162. Pressing the electric push rod 134 raises the gripper structure 16, which moves towards the clamping port 136 via the linear slide rail 141. After moving into position, the electric push rod 164 moves backward, driving the slide rod 163 backward, thus closing the upper gripper 161 and lower gripper 162, thereby pulling out the filter screen from the clamping port until a new filter screen is pulled out from the drum and passes through the filter screen guide. The filter screen is moved to the clamping port 136 and the pulling action is stopped. The electric push rod 134 is pressed down so that the lower pressure block 131 and the upper pressure block 132 clamp the filter screen. The blocked part of the filter screen is cut by the laser cutting mechanism 15, thereby completing the automatic and rapid replacement of the filter screen without stopping the machine. This enables continuous production, precise filtration, and reduced manual intervention, avoiding the entry of unfiltered melt into the product due to delays caused by manual screen replacement. The final flame-retardant and anti-dripping fiber has both excellent flame-retardant and anti-dripping properties and stable physical and mechanical properties. This preparation method achieves a significant improvement in the performance of flame-retardant and anti-dripping fibers through multi-stage synergistic optimization.

[0064] Example 2

[0065] Unlike Example 1, a process for preparing a flame-retardant and anti-dripping fiber includes the following steps:

[0066] S1, Raw material mixing: Dry the PET resin at 125℃ for 6 hours to remove moisture; weigh all raw materials according to the formula ratio, place them in a high-speed mixer, and mix at 1000 rpm for 12 minutes to ensure that the materials are fully and evenly mixed.

[0067] S2, high-efficiency filtration: The uniformly mixed polymer mixture is fed into the screw extruder and immediately connected to the fully automatic filter screen replacement filter device 1 for filtration after extrusion. By replacing the filter screen, impurities are efficiently removed, continuous filtration is ensured, and melt uniformity is improved.

[0068] S3, melt extrusion, which involves extruding the polymer melt after high-efficiency filtration through a spinneret to form a melt stream;

[0069] S4, step-by-step cooling and solidification: the melt stream is cooled in a gradient by the slow cooling device 2 to promote uniform fiber solidification, reduce stress and defects, improve flame retardant and anti-dripping performance stability, and form nascent fibers.

[0070] S5, Post-processing: The nascent fibers are stretched and heat-set. The stretching ratio is 2-5 times and the stretching temperature is 100℃. The heat-setting temperature is 200℃ and the time is 10 minutes to obtain flame-retardant and anti-dripping fibers.

[0071] High flame retardant formula

[0072]

[0073] Example 3

[0074] Unlike Example 1, a process for preparing a flame-retardant and anti-dripping fiber includes the following steps:

[0075] S1, Raw material mixing: Dry the PET resin at 130℃ for 7 hours to remove moisture; weigh all raw materials according to the formula ratio, place them in a high-speed mixer, and mix at 1000 rpm for 12 minutes to ensure that the materials are fully and evenly mixed.

[0076] S2, high-efficiency filtration: The uniformly mixed polymer mixture is fed into the screw extruder and immediately connected to the fully automatic filter screen replacement filter device 1 for filtration after extrusion. By replacing the filter screen, impurities are efficiently removed, continuous filtration is ensured, and melt uniformity is improved.

[0077] S3, melt extrusion, which involves extruding the polymer melt after high-efficiency filtration through a spinneret to form a melt stream;

[0078] S4, step-by-step cooling and solidification: the melt stream is cooled in a gradient by the slow cooling device 2 to promote uniform fiber solidification, reduce stress and defects, improve flame retardant and anti-dripping performance stability, and form nascent fibers.

[0079] S5, Post-processing: The nascent fibers are stretched and heat-set. The stretching ratio is 5 times and the stretching temperature is 120°C. The heat-setting temperature is 220°C and the time is 15 minutes to obtain flame-retardant and anti-dripping fibers.

[0080] High-strength anti-drip formulation

[0081]

[0082] Comparative Example

[0083] Unlike Example 1, the same formulation fibers were prepared using a traditional manual screen changing and single-stage cooling process.

[0084] III. Performance Testing and Results

[0085]

[0086] IV. Results Analysis

[0087] 1. Flame retardant performance: Example 2 has the highest limiting oxygen index and the shortest vertical burning length due to a significant increase in the proportion of flame retardant, resulting in the best flame retardant effect; Example 3 has a lower amount of flame retardant, resulting in relatively weaker performance in terms of LOI and burning length.

[0088] 2. Mechanical properties: Example 3, with its higher PET resin content, exhibits the best tensile strength and elongation at break; Example 2, due to its higher content of flame retardant, has a certain negative impact on mechanical properties.

[0089] 3. Anti-drip performance: All three examples achieved a drip-free effect, indicating that the anti-drip additive played an effective role in the formulation design.

[0090] The same formulated fibers prepared using traditional manual screen changing and single-stage cooling processes, as compared to those used in the comparative experiment, exhibited a melt-drip rate of 15 drops / 10s, an LOI of 30%, and a breaking strength of 3.2 cN / dtex. In this embodiment of the invention, the fully automatic screen-changing filtration device effectively reduces impurity introduction and production interruptions; the slow cooling device (especially its gradient cooling method) refines the fiber structure and optimizes the distribution of flame retardants. These improvements collectively result in a significant enhancement of the fiber's anti-drip properties and mechanical properties.

Claims

1. A process for preparing flame-retardant and anti-dripping fibers, characterized in that, Includes the following steps: S1, Raw material mixing: Dry the PET resin at 120-130℃ for 5-7 hours to remove moisture; weigh all raw materials according to the formula ratio and place them in a high-speed mixer to mix the materials thoroughly and evenly. S2, high-efficiency filtration, the uniformly mixed polymer mixture is fed into the screw extruder, and immediately after extrusion, it is connected to the fully automatic filter screen replacement filter device (1) for filtration; S3, melt extrusion, which involves extruding the polymer melt after high-efficiency filtration through a spinneret to form a melt stream; S4, stepwise cooling and solidification: the melt stream is cooled in a gradient by a slow cooling device (2) to promote uniform solidification of the fiber and form nascent fiber; S5, Post-processing: The nascent fibers are subjected to stretching and heat setting treatment. The stretching ratio is 2-5 times, and the stretching temperature is 80-120℃; the heat setting temperature is 180-220℃, and the time is 5-15 minutes, to obtain flame-retardant and anti-dripping fibers. The fully automatic filter replacement filter device (1) includes a fixed plate (11), a roller (12), a pressing and clamping mechanism (13), a pulling mechanism (14), and a laser cutting mechanism (15). The fixed plate (11) has a filter guide groove (110) from left to right. The top of the fixed plate (11) has a guide hole (111). The roller (12) is located in the inlet direction of the filter guide groove (110). The pressing and clamping mechanism (13) is located in the outlet direction of the filter guide groove (110). The pulling mechanism (14) is located behind the pressing and clamping mechanism (13). The laser cutting mechanism (15) is located above the pressing and clamping mechanism (13) and is used to cut the filter screen. It also includes a differential pressure sensor with two pressure ports, which are connected to the filter screen inlet and outlet respectively. The sensor measures the pressure difference between the upstream and downstream of the filter screen. When the pressure difference increases beyond the set threshold, it indicates that the filter screen is clogged. The pressing and clamping mechanism (13) includes a lower pressing block (131), an upper pressing block (132), a connecting plate (133), a pressing electric push rod (134), and a fixing frame (135). The fixing frame (135) is fixed at the outlet of the filter screen guide groove (110). Several lower pressing blocks (131) are linearly arrayed on the fixing frame (135) and located below the filter screen guide groove (110). A clamping port (136) is provided between two adjacent lower pressing blocks (131) for easy clamping. Each lower pressing block (131) is provided with an upper pressing block (132) above it. The upper pressing block (132) is fixed on the connecting plate (133). The push rod end of the pressing electric push rod (134) is fixedly connected to the connecting plate (133). The motor end of the pressing electric push rod (134) is fixed on the fixing frame (135). The pull-out mechanism (14) includes a linear slide rail (141), a slider (142), a connecting bar (143), and a gripper structure (16). The two linear slide rails (141) are located on both sides of the lower pressure block (131) and fixed on the fixing frame (135). The slider (142) is slidably located on the linear slide rail (141). The connecting bar (143) is located between the two sliders (142). Several gripper structures (16) are fixed on the connecting bar (143). Each gripper structure (16) corresponds to a gripping port (136). The gripper structure (16) includes an upper gripper (161), a lower gripper (162), a slide rod (163), a slide rod electric push rod (164), and a fixing block (165). The fixing block (165) is fixed on the connecting strip (143). A groove (166) is provided in the fixing block (165). The slide rod (163) is located in the groove (166). The slide rod electric push rod (164) is located in the groove (166), and its push rod end is fixed to the slide rod. At the end of (163), the front end of the fixing block (165) is provided with an extension plate (167), the rear end of the lower jaw (162) is provided with a first mounting plate (168), the rear end of the upper jaw (161) is provided with two second mounting plates (169), the slide rod (163) is hinged to the first mounting plate (168), the first mounting plate (168) is hinged to the second mounting plate (169), and the extension plate (167) is hinged to the second mounting plate (169). The slow cooling device (2) includes a cooling coil (21), with a water inlet (210) at the bottom and a water outlet (211) at the top.

2. The preparation process of a flame-retardant and anti-dripping fiber according to claim 1, characterized in that, A pressure ring (17) is provided above the flow guide hole (111) of the fixed plate (11). A filter screen passage space (175) is left between the bottom of the pressure ring (17) and the fixed plate (11). A tightening rod (171) is provided at the top of the pressure ring (17). An electric push rod (172) for the pressure ring is provided at the top of the tightening rod (171). A limiting groove (173) is opened at the position of the top of the pressure ring (17) corresponding to the position of the tightening rod (171). A magnet (174) is provided in the limiting groove (173).

3. The preparation process of a flame-retardant and anti-dripping fiber according to claim 1, characterized in that, The inner sides of the upper jaw (161) and lower jaw (162) are provided with rubber pads (160).

4. The preparation process of a flame-retardant and anti-dripping fiber according to claim 1, characterized in that, The outer wall of the cooling coil (21) is provided with a heat dissipation pipe (212), and the heat dissipation pipe (212) is provided with a plurality of heat dissipation fins (213).

5. The preparation process of a flame-retardant and anti-dripping fiber according to claim 4, characterized in that, The outlet (211) is connected to a radiator, and the outlet of the radiator is connected to the inlet (210) of the cooling coil (21).

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