Melting, dipping and weaving process of flame-retardant fiber reinforced thermoplastic filling rope

Abstract

The invention relates to the technical field of fiber reinforcement, and discloses a melt impregnation weaving process of a flame-retardant fiber reinforced thermoplastic filling rope, the melt impregnation weaving process comprises fiber pretreatment, melt impregnation, multi-stage stretching setting, weaving forming and post-treatment, through the synergistic effect of plasma activation and nano flame-retardant pretreatment, the fiber surface activity and the flame retardant binding force are improved, and the flame-retardant fiber reinforced thermoplastic filling rope is obtained. Meanwhile, a segmented temperature control melt impregnation process is combined, so that the resin is ensured to form a uniform and complete coating layer on the surface of the fiber monofilament, the problems of weakening of interface bonding and non-uniform flame-retardant distribution in a traditional process are solved, and the flame-retardant efficiency and mechanical reliability of the filling rope are improved; a dynamic mathematical model of the tension gradient and the traction speed is established, the fiber crystallization orientation process is controlled, and the internal stress concentration phenomenon is eliminated; in combination with a dynamic tension compensation mechanism during weaving forming, the weaving tightness of the coating layer is corrected in real time, and the dimensional stability and the anti-fatigue performance of the filling rope under the complex load are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fiber reinforced technology, in particular to a melt impregnation braiding process of flame-retardant fiber reinforced thermoplastic filling rope. BACKGROUND

[0002] The flame-retardant fiber refers to the fiber which only smolders in the flame, does not generate flame itself, and self-extinguishes after leaving the flame, and is widely used in clothing, home, decoration, non-woven fabric and filler, etc. Compared with ordinary fibers, the flame-retardant fiber has reduced flammability, slowed down burning rate in the combustion process, can self-extinguish rapidly after leaving the fire source, and releases less toxic smoke.

[0003] At present, in the production process of the flame-retardant fiber reinforced thermoplastic filling rope, due to the inherent contradiction between the fiber surface inertness and the resin melt wettability, the traditional pretreatment process is difficult to realize the uniform penetration of the flame retardant on the fiber monofilament scale, resulting in micro defects in the interface bonding area. In the melt impregnation stage, improper control of the temperature field and the pressure field easily causes incomplete resin coating or local accumulation, so that stress concentration weak points are formed inside the filling rope. The static tension distribution mechanism in the braiding forming process cannot adapt to the dynamic changes under high-speed traction, causing the coating layer structure to be loose or too tight, and further weakening the rope body fatigue resistance. The hot air treatment method in the solidification stage is difficult to realize the deep crosslinking of the resin molecular chain due to the low heat conduction efficiency, finally resulting in the systematic risks of flame-retardant failure, mechanical property attenuation and insulation performance degradation of the filling rope under high temperature, high humidity or long-term load working conditions.

[0004] Therefore, the melt impregnation braiding process of the flame-retardant fiber reinforced thermoplastic filling rope is proposed to solve the above problems. SUMMARY

[0005] In view of the deficiencies of the prior art, the melt impregnation braiding process of the flame-retardant fiber reinforced thermoplastic filling rope is provided to solve the problems of incomplete resin coating or local accumulation, weak rope body fatigue resistance, flame-retardant failure, mechanical property attenuation and insulation performance degradation in the background technology.

[0006] To achieve the above purpose, the present application provides the following technical solutions: the melt impregnation braiding process of the flame-retardant fiber reinforced thermoplastic filling rope, comprising the following steps: Step one, fiber pretreatment: aramid 1414 fiber or ultrahigh molecular weight polyethylene fiber is selected as the reinforcing matrix, the monofilament fineness is 200-500D, after being unfolded by a filament separating roller, the fiber is sequentially passed through a plasma surface activation device and a flame-retardant pretreatment tank; The plasma treatment power is 300-800W, the treatment time is 30-90s, and the flame-retardant pretreatment liquid is composed of nano-aluminum hydroxide and silane coupling agent KH-560 with a mass ratio of 1:5-10; Step 2: Melt impregnation: The pretreated fiber bundle is introduced into a vertical impregnation mold. The mold temperature is controlled at 20-50°C higher than the melting point of the thermoplastic resin so that the molten resin completely covers the monofilaments. The thermoplastic resin is at least one of polyetheretherketone (PEEK), polyphenylene sulfide (PPS) or flame retardant modified polyamide (PA66), and has a melt viscosity of 200-800 Pa·s; Step 3: Multi-stage stretching and shaping: The impregnated fiber bundle is drawn through a three-stage tension control system, with the first-stage tension being 0.5-1.5 N / tex, the second-stage tension being 1.5-3.0 N / tex, and the third-stage tension being 3.0-5.0 N / tex. The drawing speed is 10-30 m / min, and the fiber bundle is cooled to below 80°C on the shaping roller group. Step 4: Braiding: 8-24 impregnated fiber bundles are used as core yarns, and the covering layer is braided in a 2+2 or 3+3 structure using a twisted braiding machine. The covering layer is processed using the same melt impregnation process as in step 2, with a braiding angle of 30°-60° and a braiding density of 90-150 twists / m; Step 5: Post-processing: The braided body passes through a microwave cross-linking device with a power of 1-5kW, a frequency of 2.45GHz, and a processing time of 2-10min, and is finally wound into shape by a winder.

[0007] Preferably, the plasma surface activation in step 1 is carried out at a vacuum degree of - The gas medium is a mixture of argon and oxygen with a volume ratio of 8:2-9:1, and the proportion of oxygen is precisely controlled to be 10%-12%.

[0008] Preferably, the flame retardant pretreatment tank is provided with an ultrasonic oscillator with a frequency of 28-40kHz and a power density of 0.5-2.0W / cm 2 The treatment time is 5-15 minutes, the bath temperature is maintained at 40-60°C, and the ultrasonic cavitation effect makes the nanoparticles penetrate to a depth of 15%-25% of the single fiber diameter.

[0009] Preferably, the thermoplastic resin in step 2 comprises the following raw materials in parts by weight: 70-85 parts of base resin, 10-20 parts of composite flame retardant, 5-10 parts of functional additives; The composite flame retardant consists of ammonium polyphosphate, melamine cyanurate and zinc borate in a mass ratio of 3:2:1.

[0010] Preferably, the functional additive is prepared by the following method: The waste silicon carbide ceramic powder was ball-milled to a particle size of 1-5 μm and ultrasonically cleaned in 15% mass fraction nitric acid for 30 min; After cleaning, the powder is placed in a plasma fluidized bed, and hexamethyldisilazane vapor is introduced, with a pressure of 0.1-0.5 MPa, a power of 1-3 kW, and a treatment time of 10-30 min. The surface-modified powder and nano-titanium dioxide are mixed at a mass ratio of 7:3, and dispersed in a high-speed mixer at 1200 r / min for 15 min.

[0011] Preferably, the vertical impregnation mold adopts a segmented temperature control structure, comprising: An inlet section: resin melting point-20℃ to melting point, length 100-200mm; An impregnation section: melting point+20℃ to +50℃, length 300-500mm; An outlet section: melting point-10℃ to +10℃, length 50-100mm; The mold cavity pressure is maintained at 2.0-5.0 MPa by a hydraulic system, and the pressure gradient difference controls the resin to penetrate along the fiber axis.

[0012] Preferably, the three-stage tension control system contains a closed-loop feedback module, with a tension fluctuation deviation of ≤±0.2 N / tex, and the pulling speed and tension satisfy the relationship: ; Wherein is the pulling speed, is the total tension, is a process constant of 0.8-1.2.

[0013] Preferably, the spindle of the double-twist braider is equipped with a driven unwinding device, with an unwinding tension of 0.1-0.5 N / tex, and the ratio of spindle speed to pulling speed is controlled at 1.05-1.20 times, and the cladding layer thickness accounts for 15%-35% of the total diameter of the filled rope.

[0014] Preferably, the microwave crosslinking device is provided with a nitrogen protection system, with an oxygen content of ≤100 ppm, a microwave power density of 0.5-2.0 W / g, and after crosslinking, the resin crystallinity is increased to 40%-60%, and the molecular chain orientation degree is increased to make the heat distortion temperature reach above 280℃.

[0015] Preferably, the final filled rope meets the following performance indicators: Ultimate tensile strength ≥350 MPa; Flame retardant grade UL94 V-0, 1.6mm thickness; Dielectric strength ≥25kV / mm; 24h water absorption ≤0.5%; 400℃ thermal weight loss ≤8%; and the axial compression fatigue life reaches 10 7 times, with a load of 50% of the ultimate strength.

[0016] (Three) beneficial effects Compared with the prior art, the present application provides a melt impregnation braiding process of flame-retardant fiber reinforced thermoplastic filled rope, which has the following beneficial effects: 1. In the melt impregnation braiding process of flame-retardant fiber reinforced thermoplastic filled rope, the surface activity of the fiber and the bonding force of the flame retardant are improved through the synergistic effect of plasma activation and nano flame retardant pretreatment, and the melt impregnation process with segmented temperature control is combined to ensure that the resin forms a uniform and complete coating layer on the surface of the fiber monofilament, solve the problem of weak interface bonding and uneven distribution of flame retardant in the traditional process, and improve the flame retardant efficiency and mechanical reliability of the filled rope.

[0017] 2. In the fiber bundle multi-stage stretching and setting stage, the dynamic mathematical model of tension gradient and traction speed is established to control the fiber crystallization orientation process and eliminate internal stress concentration; combined with the dynamic tension compensation mechanism during braiding, the tightness of the coating layer is corrected in real time to avoid structural defects of the rope body caused by tension fluctuation, and the dimensional stability and fatigue resistance of the filled rope under complex load are ensured.

[0018] 3. In the post-processing stage of the filled rope, the synergistic effect of microwave crosslinking and nitrogen protection promotes the directional crosslinking of resin molecular chains and inhibits high-temperature oxidation, simultaneously improving the crystallinity and thermal stability; combined with multi-region material function design, the flame retardancy, insulation and environmental resistance of the filled rope are synergistically optimized to meet the stringent requirements of extreme working conditions on comprehensive performance. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0020] Embodiment 1: A melt impregnation braiding process of flame-retardant fiber reinforced thermoplastic filled rope, comprising the following steps: Step one, fiber pretreatment: aramid 1414 fiber or ultrahigh molecular weight polyethylene fiber is selected as the reinforcing matrix, the monofilament fineness is 200D, after being spread by a fiber spreading roller, it passes through a plasma surface activation device and a flame retardant pretreatment tank in sequence; The plasma treatment power is 300W, the treatment time is 30s, and the flame retardant pretreatment liquid is composed of nano-aluminum hydroxide and silane coupling agent KH-560 with a mass ratio of 1:5; Step 2: Melt impregnation: The pretreated fiber bundle is introduced into a vertical impregnation mold. The mold temperature is controlled at 20°C higher than the melting point of the thermoplastic resin so that the molten resin completely covers the monofilaments. The thermoplastic resin is at least one of polyetheretherketone (PEEK), polyphenylene sulfide (PPS) or flame retardant modified polyamide (PA66), and has a melt viscosity of 200 Pa·s; Step 3: Multi-stage stretching and shaping: The impregnated fiber bundle is drawn through a three-stage tension control system, with the first-stage tension being 0.5N / tex, the second-stage tension being 1.5N / tex, and the third-stage tension being 3.0N / tex. The drawing speed is 10m / min, and the fiber bundle is cooled to below 80°C on the shaping roller group. Step 4: Braiding: 8 impregnated fiber bundles are used as core yarns and braided into a covering layer in a 2+2 or 3+3 structure using a twisted braiding machine. The covering layer is processed using the same melt impregnation process as in step 2, with a braiding angle of 30° and a braiding density of 90 twists / m. Step 5, post-processing: the braided body passes through a microwave cross-linking device with a power of 1 kW, a frequency of 2.45 GHz, and a processing time of 2 minutes, and is finally wound into shape by a winder.

[0021] In step 1, plasma surface activation is performed at a vacuum The gas medium is a mixture of argon and oxygen with a volume ratio of 8:2, in which the proportion of oxygen is precisely controlled to be 10%.

[0022] The flame retardant pretreatment tank is equipped with an ultrasonic oscillator with a frequency of 28kHz and a power density of 0.5W / cm 2 The treatment time was 5 min, the bath temperature was maintained at 40 ° C, and the ultrasonic cavitation effect made the nanoparticles penetrate to a depth of 15% of the single fiber diameter.

[0023] The thermoplastic resin in step 2 comprises the following raw materials in parts by weight: 70 parts of base resin, 10 parts of composite flame retardant, 5 parts of functional additives; The composite flame retardant consists of ammonium polyphosphate, melamine cyanurate and zinc borate in a mass ratio of 3:2:1.

[0024] The functional additive is prepared by the following method: Waste silicon carbide ceramic powder was ball-milled to a particle size of 1 μm and ultrasonically cleaned in 15% mass fraction nitric acid for 30 min; After cleaning, the powder was placed in a plasma fluidized bed and hexamethyldisilazane vapor was introduced at a pressure of 0.1 MPa and a power of 1 kW for 10 min. The surface modified powder and nano-titanium dioxide were mixed in a mass ratio of 7:3 and dispersed in a high-speed mixer at 1200 r / min for 15 min.

[0025] The vertical impregnation mold adopts a segmented temperature control structure, including: Inlet section: resin melting point -20℃ to melting point, length 100mm; Dipping section: melting point +20℃ to +50℃, length 300mm; Outlet section: melting point -10℃ to +10℃, length 50mm; The mold cavity pressure is maintained at 2.0 MPa by a hydraulic system, and the pressure gradient difference controls the resin penetration along the fiber axis.

[0026] The three-level tension control system includes a closed-loop feedback module. The tension fluctuation deviation is ≤±0.2N / tex. The pulling speed and tension satisfy the relationship: ; in is the traction speed (m / min), is the total tension (N / tex), The process constant is 0.8-1.2.

[0027] The spindle of the twisted-pair braiding machine is equipped with an active unwinding device with an unwinding tension of 0.1N / tex. The ratio of spindle speed to traction speed is controlled at 1.05 times, and the coating thickness accounts for 15% of the total diameter of the filling rope.

[0028] The microwave cross-linking device is equipped with a nitrogen protection system, the oxygen content is ≤100ppm, the microwave power density is 0.5W / g, the resin crystallinity is increased to 40% after cross-linking, and the molecular chain orientation is increased so that the thermal deformation temperature reaches above 280°C.

[0029] The final filling rope meets the following performance indicators: Ultimate tensile strength ≥350MPa; Flame retardant grade UL94 V-0, 1.6mm thickness; Dielectric strength ≥25kV / mm; 24h water absorption rate ≤0.5%; Thermal weight loss at 400℃≤8%; And the axial compression fatigue life is up to 10 7 times, the load is 50% of the ultimate strength.

[0030] Example 2: A melt-impregnation braiding process for flame-retardant fiber-reinforced thermoplastic filling rope, comprising the following steps: Step 1: Fiber pretreatment: Aramid 1414 fiber or ultra-high molecular weight polyethylene fiber is selected as the reinforcing matrix, with a single fiber fineness of 350D. After being spread out by the separation roller, it passes through the plasma surface activation device and the flame retardant pretreatment tank in sequence; The plasma treatment power is 550 W, the treatment time is 60 s, and the flame-retardant pretreatment liquid is composed of nano-aluminum hydroxide and silane coupling agent KH-560 in a mass ratio of 1:8; Step two, melt impregnation: the pretreated fiber bundle is introduced into a vertical impregnation mold, the mold temperature is controlled at 35 DEG C higher than the melting point of the thermoplastic resin, and the molten resin completely covers the monofilament; The thermoplastic resin is at least one of polyether ether ketone (PEEK), polyphenylene sulfide (PPS) or flame-retardant modified polyamide (PA66), and the melt viscosity is 500 Pa s; Step three, multi-stage stretching and setting: the impregnated fiber bundle is pulled through a three-stage tension control system, the first-stage tension is 1.0 N / tex, the second-stage tension is 2.3 N / tex, the third-stage tension is 4.0 N / tex, the pulling speed is 20 m / min, and the temperature is cooled to below 80 DEG C on the setting roller group; Step four, braiding forming: 16 impregnated fiber bundles are used as core yarns, a double-twisted braiding machine is used to braid the cover layer in a 2+2 or 3+3 structure, the cover layer is treated by the same melt impregnation process as in step two, the braiding angle is 45 DEG, and the braiding density is 120 twists per meter; Step five, post-treatment: the braided body is treated by a microwave crosslinking device, the power is 3 kW, the frequency is 2.45 GHz, the treatment time is 6 min, and finally it is wound into a roll by a winding machine.

[0031] The plasma surface activation in step one is carried out under a vacuum degree of 0.1 Pa, and the gas medium is a mixture of argon and oxygen with a volume ratio of 9:1, wherein the oxygen ratio is accurately controlled to be 11%.

[0032] The flame-retardant pretreatment tank is provided with an ultrasonic oscillator, the frequency is 34 kHz, the power density is 1.3 W / cm 2 , the treatment time is 10 min, and the tank liquid temperature is maintained at 50 DEG C. The ultrasonic cavitation effect makes the nano-particle penetration depth reach 20% of the diameter of the monofilament.

[0033] The thermoplastic resin in step two comprises the following raw materials by weight: 80 parts of base resin, 15 parts of composite flame retardant, and 8 parts of functional additive; The composite flame retardant is composed of ammonium polyphosphate, melamine cyanurate and zinc borate in a mass ratio of 3:2:1.

[0034] The functional additive is prepared by the following method: The waste silicon carbide ceramic powder is ball milled to a particle size of 3 μm, and then ultrasonically cleaned in 15% nitric acid for 30 min; After cleaning, the powder is placed in a plasma fluidized bed, and hexamethyldisilazane vapor is introduced, the pressure is 0.3 MPa, the power is 2 kW, and the treatment time is 20 min; ​The surface modified powder and nano-titanium dioxide are mixed at a mass ratio of 7:3, and dispersed in a high-speed mixer at 1200 r / min for 15 min.

[0035] The vertical impregnation mold adopts a segmented temperature control structure, comprising: The inlet section: resin melting point-20℃ to melting point, length 150mm; The impregnation section: melting point+20℃ to +50℃, length 400mm; The outlet section: melting point-10℃ to +10℃, length 75mm; The mold cavity pressure is maintained at 3.5MPa by a hydraulic system, and the pressure gradient difference controls the axial permeability of the resin along the fiber.

[0036] The three-stage tension control system includes a closed-loop feedback module, and the tension fluctuation deviation is ≤±0.2N / tex, and the traction speed and tension satisfy the relationship: ; Wherein is the traction speed (m / min), is the total tension (N / tex), is the process constant 0.8-1.2.

[0037] The spindle of the double-twisted braiding machine is equipped with a driven unwinding device, the unwinding tension is 0.3N / tex, the spindle speed and the traction speed ratio are controlled at 1.15 times, and the cladding layer thickness accounts for 25% of the total diameter of the filled rope.

[0038] The microwave crosslinking device is provided with a nitrogen protection system, the oxygen content is ≤100ppm, the microwave power density is 1.3W / g, the crystallinity of the resin after crosslinking is increased to 50%, and the thermal distortion temperature is above 280℃ due to the increase of the molecular chain orientation degree.

[0039] The final filled rope meets the following performance indicators: Ultimate tensile strength ≥350MPa; Flame retardant grade UL94 V-0, 1.6mm thickness; Dielectric strength ≥25kV / mm; 24h water absorption ≤0.5%; 400℃ thermal weight loss ≤8%; And the axial compression fatigue life reaches 10 7 times, and the load is 50% of the ultimate strength.

[0040] Example 3: melt impregnation braiding process of flame-retardant fiber reinforced thermoplastic filled rope, comprising the following steps: Step 1: Fiber pretreatment: Aramid 1414 fiber or ultra-high molecular weight polyethylene fiber is selected as the reinforcing matrix, with a single fiber fineness of 500D. After being spread out by the separation roller, it passes through the plasma surface activation device and the flame retardant pretreatment tank in sequence; The plasma treatment power was 800 W, the treatment time was 90 s, and the flame retardant pretreatment solution consisted of nano-aluminum hydroxide and silane coupling agent KH-560 in a mass ratio of 1:10; Step 2: Melt impregnation: The pretreated fiber bundle is introduced into a vertical impregnation mold. The mold temperature is controlled at 50°C higher than the melting point of the thermoplastic resin so that the molten resin completely covers the monofilaments. The thermoplastic resin is at least one of polyetheretherketone (PEEK), polyphenylene sulfide (PPS) or flame retardant modified polyamide (PA66), and has a melt viscosity of 800 Pa·s; Step 3: Multi-stage stretching and shaping: The impregnated fiber bundle is drawn through a three-stage tension control system with a first-stage tension of 1.5 N / tex, a second-stage tension of 3.0 N / tex, and a third-stage tension of 5.0 N / tex at a speed of 30 m / min, and is cooled to below 80°C on a shaping roller group. Step 4: Braiding: 24 impregnated fiber bundles are used as core yarns and braided into a covering layer in a 2+2 or 3+3 structure using a twisted braiding machine. The covering layer is processed using the same melt impregnation process as in step 2, with a braiding angle of 60° and a braiding density of 150 twists / m. Step 5, post-processing: the braided body passes through a microwave cross-linking device with a power of 5kW, a frequency of 2.45GHz, and a processing time of 10 minutes, and is finally rolled up by a winder.

[0041] In step 1, plasma surface activation is performed at a vacuum The gas medium is a mixture of argon and oxygen with a volume ratio of 9:1, in which the proportion of oxygen is precisely controlled to be 12%.

[0042] The flame retardant pretreatment tank is equipped with an ultrasonic oscillator with a frequency of 40kHz and a power density of 2.0W / cm 2 The treatment time was 15 min, the bath temperature was maintained at 60 °C, and the ultrasonic cavitation effect made the nanoparticles penetrate to a depth of 25% of the single fiber diameter.

[0043] The thermoplastic resin in step 2 comprises the following raw materials in parts by weight: 85 parts of base resin, 20 parts of composite flame retardant, 10 parts of functional additives; The composite flame retardant consists of ammonium polyphosphate, melamine cyanurate and zinc borate in a mass ratio of 3:2:1.

[0044] The functional additive is prepared by the following method: The waste silicon carbide ceramic powder is ball milled to a particle size of 5 μm, and is ultrasonically cleaned in 15% nitric acid by mass fraction for 30 min. After cleaning, the powder is placed in a plasma fluidized bed, and hexamethyldisilazane vapor is introduced, with a pressure of 0.5 MPa, a power of 3 kW, and a treatment time of 30 min. The surface-modified powder is mixed with nano-titanium dioxide at a mass ratio of 7:3, and is dispersed in a high-speed mixer at 1200 r / min for 15 min.

[0045] The vertical impregnation mold adopts a segmented temperature control structure, and comprises: An inlet section: resin melting point-20℃ to melting point, length 200 mm; An impregnation section: melting point+20℃ to +50℃, length 500 mm; An outlet section: melting point-10℃ to +10℃, length 100 mm; The mold cavity pressure is maintained at 5.0 MPa by a hydraulic system, and the pressure gradient difference controls the resin to permeate along the fiber axis.

[0046] The three-stage tension control system comprises a closed-loop feedback module, and the tension fluctuation deviation is ≤±0.2 N / tex, and the traction speed and the tension satisfy the following relationship: ; Wherein is the traction speed, is the total tension, is a process constant of 0.8-1.2.

[0047] The spool of the double-twist braider is equipped with a driven unwinding device, the unwinding tension is 0.5 N / tex, the spool speed and the traction speed ratio is controlled at 1.20 times, and the cladding layer thickness accounts for 35% of the total diameter of the filled rope.

[0048] The microwave crosslinking device is provided with a nitrogen protection system, the oxygen content is ≤100 ppm, the microwave power density is 2.0 W / g, the crystallinity of the resin after crosslinking is increased to 60%, and the thermal distortion temperature is above 280℃ due to the increase of the molecular chain orientation degree.

[0049] The final filled rope meets the following performance indicators: Ultimate tensile strength ≥350 MPa; Flame retardant grade UL94 V-0, 1.6 mm thickness; Dielectric strength ≥25 kV / mm; 24h water absorption ≤0.5%; 400℃ thermal weight loss ≤8%; and the axial compression fatigue life reaches 10 7 times, and the load is 50% of the ultimate strength.

[0050] Comparative Example 1, the difference between this comparative example and Example 1 is that no functional additives are added in the melt impregnation stage.

[0051] Comparative Example 2, the difference between this comparative example and Example 1 is that no nano-aluminum hydroxide and silane coupling agent composite flame-retardant liquid is used in the flame-retardant pretreatment stage.

[0052] Comparative Example 3, the difference between this comparative example and Example 1 is that no plasma surface activation treatment is performed.

[0053] Comparative Example 4, the difference between this comparative example and Example 1 is that the dynamic tension compensation system is closed in the braiding forming stage.

[0054] The filled ropes prepared in Examples 1-3 and Comparative Examples 1-4 are subjected to performance testing, and the test items and methods are as follows: Ultimate tensile strength test: using a universal material testing machine, the tensile rate is 100 mm / min, and the maximum load at which the sample breaks is recorded; Flame-retardant performance test: vertical burning method, flame height 20 mm, flame application time 10 s, self-extinguishing time and carbonization length are recorded; Dielectric strength test: stepwise voltage increase in oil medium, voltage increase amplitude 0.5 kV / s, breakdown voltage value is recorded; Hygrothermal aging test: 85°C temperature, 85% RH humidity environment treatment for 500 hours, strength retention rate after aging is tested.

[0055] The performance test data of the filled ropes prepared in Examples 1-3 and Comparative Examples 1-4 are recorded in the following table:

[0056] By comparing and analyzing the data in the table, it can be seen that the flame-retardant fiber-reinforced thermoplastic filling rope prepared by the processes of examples 1-3 has more excellent performance than the filling ropes prepared by the processes of comparative examples 1-4, which shows that the process can improve the surface activity of the fiber and the bonding force of the flame retardant through the synergistic effect of plasma activation and nano flame retardant pretreatment during the melt impregnation and braiding process of the flame-retardant fiber-reinforced thermoplastic filling rope, and can ensure that the resin forms a uniform and complete coating layer on the surface of the fiber monofilament by combining the segmented temperature control melt impregnation process, solve the problems of weak interface bonding and uneven distribution of flame retardant in the traditional process, and improve the flame-retardant efficiency and mechanical reliability of the filling rope; during the multi-stage stretching and setting stage of the fiber bundle, the dynamic mathematical model of the tension gradient and the traction speed is established to control the fiber crystallization orientation process and eliminate the internal stress concentration phenomenon; at the same time, the dynamic tension compensation mechanism during braiding is combined to real-time correct the tightness of the coating layer during braiding, avoid the structural defects of the rope body caused by tension fluctuation, and ensure the dimensional stability and fatigue resistance of the filling rope under complex load; in the post-processing stage of the filling rope, the synergistic effect of microwave crosslinking and nitrogen protection promotes the directional crosslinking of the resin molecular chain and inhibits high-temperature oxidation, and simultaneously improves the crystallinity and thermal stability; combined with the multi-region material function design, the flame retardancy, insulation and environmental resistance of the filling rope are synergistically optimized to meet the stringent requirements of extreme working conditions on comprehensive performance.

[0057] By comparing and analyzing the related data in the table, it can be seen that the flame-retardant fiber-reinforced thermoplastic filling rope prepared by the molding process of the application has excellent tensile strength, self-extinguishing flame retardancy and dielectric stability. Therefore, it is shown that the melt impregnation and braiding process of the flame-retardant fiber-reinforced thermoplastic filling rope provided by the application has a broader market prospect and is more suitable for promotion.

[0058] It should be noted that, in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... " does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0059] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. The melt-impregnation braiding process of flame-retardant fiber reinforced thermoplastic filling rope is characterized by: The following steps are involved: Step 1: Fiber pretreatment: Aramid 1414 fiber or ultra-high molecular weight polyethylene fiber is selected as the reinforcing matrix, with a single fiber fineness of 200-500D. After being spread out by the separation roller, it passes through the plasma surface activation device and the flame retardant pretreatment tank in sequence; The plasma treatment power is 300-800W, the treatment time is 30-90s, and the flame retardant pretreatment liquid is composed of nano-aluminum hydroxide and silane coupling agent KH-560 in a mass ratio of 1:5-10; Step 2: Melt impregnation: The pretreated fiber bundle is introduced into a vertical impregnation mold. The mold temperature is controlled at 20-50°C higher than the melting point of the thermoplastic resin so that the molten resin completely covers the monofilaments. The thermoplastic resin is at least one of polyetheretherketone (PEEK), polyphenylene sulfide (PPS) or flame retardant modified polyamide (PA66), and has a melt viscosity of 200-800 Pa·s; Step 3: Multi-stage stretching and shaping: The impregnated fiber bundle is drawn through a three-stage tension control system, with the first-stage tension being 0.5-1.5 N / tex, the second-stage tension being 1.5-3.0 N / tex, and the third-stage tension being 3.0-5.0 N / tex. The drawing speed is 10-30 m / min, and the fiber bundle is cooled to below 80°C on the shaping roller group. Step 4: Braiding: 8-24 impregnated fiber bundles are used as core yarns, and the covering layer is braided in a 2+2 or 3+3 structure using a twisted braiding machine. The covering layer is processed using the same melt impregnation process as in step 2, with a braiding angle of 30°-60° and a braiding density of 90-150 twists / m; Step 5: Post-processing: The braided body passes through a microwave cross-linking device with a power of 1-5kW, a frequency of 2.45GHz, and a processing time of 2-10min, and is finally wound into shape by a winder.

2. The melt-impregnation braiding process for flame-retardant fiber-reinforced thermoplastic filling rope according to claim 1, characterized in that: In the step 1, the plasma surface activation is carried out at a vacuum degree - The gas medium is a mixture of argon and oxygen with a volume ratio of 8:2-9:1, and the proportion of oxygen is precisely controlled to be 10%-12%.

3. The melt-impregnation braiding process for flame-retardant fiber-reinforced thermoplastic filling rope according to claim 1, characterized in that: The flame retardant pretreatment tank is equipped with an ultrasonic oscillator with a frequency of 28-40kHz and a power density of 0.5-2.0W / cm 2 The treatment time is 5-15 minutes, the bath temperature is maintained at 40-60°C, and the ultrasonic cavitation effect makes the nanoparticles penetrate to a depth of 15%-25% of the single fiber diameter.

4. The melt-impregnation braiding process for flame-retardant fiber-reinforced thermoplastic filling rope according to claim 1, characterized in that: The thermoplastic resin in step 2 comprises the following raw materials in parts by weight: 70-85 parts of base resin, 10-20 parts of composite flame retardant, 5-10 parts of functional additives; The composite flame retardant consists of ammonium polyphosphate, melamine cyanurate and zinc borate in a mass ratio of 3:2:

1.

5. The melt-impregnation braiding process for flame-retardant fiber-reinforced thermoplastic filling rope according to claim 4, characterized in that: The functional additive is prepared by the following method: The waste silicon carbide ceramic powder was ball-milled to a particle size of 1-5 μm and ultrasonically cleaned in 15% mass fraction nitric acid for 30 min; After cleaning, the powder is placed in a plasma fluidized bed and hexamethyldisilazane vapor is introduced at a pressure of 0.1-0.5 MPa and a power of 1-3 kW for 10-30 minutes. The surface modified powder and nano-titanium dioxide were mixed in a mass ratio of 7:3 and dispersed in a high-speed mixer at 1200 r / min for 15 min.

6. The melt-impregnation braiding process for flame-retardant fiber-reinforced thermoplastic filling rope according to claim 1, characterized in that: The vertical impregnation mold adopts a segmented temperature control structure, including: Inlet section: resin melting point -20℃ to melting point, length 100-200mm; Dipping section: melting point +20°C to +50°C, length 300-500mm; Outlet section: melting point -10℃ to +10℃, length 50-100mm; The mold cavity pressure is maintained at 2.0-5.0 MPa through a hydraulic system, and the pressure gradient difference controls the resin penetration along the fiber axis.

7. The melt-impregnation braiding process for flame-retardant fiber-reinforced thermoplastic filling rope according to claim 1, characterized in that: The three-level tension control system includes a closed-loop feedback module, the tension fluctuation deviation is ≤±0.2N / tex, and the pulling speed and tension satisfy the relationship: ； in is the traction speed, is the total tension, The process constant is 0.8-1.

2.

8. The melt-impregnation braiding process for flame-retardant fiber-reinforced thermoplastic filling rope according to claim 1, characterized in that: The spindle of the twisted double braiding machine is equipped with an active unwinding device, the unwinding tension is 0.1-0.5N / tex, the ratio of spindle speed to traction speed is controlled at 1.05-1.20 times, and the coating layer thickness accounts for 15%-35% of the total diameter of the filling rope.

9. The melt-impregnation braiding process for flame-retardant fiber-reinforced thermoplastic filling rope according to claim 1, characterized in that: The microwave cross-linking device is equipped with a nitrogen protection system, the oxygen content is ≤100ppm, the microwave power density is 0.5-2.0W / g, the resin crystallinity is increased to 40%-60% after cross-linking, the molecular chain orientation is increased so that the thermal deformation temperature reaches above 280°C.

10. The melt-impregnation braiding process for flame-retardant fiber-reinforced thermoplastic filling rope according to claim 1, characterized in that: The final filling rope meets the following performance indicators: Ultimate tensile strength ≥350MPa; Flame retardant grade UL94 V-0, 1.6mm thickness; Dielectric strength ≥25kV / mm; 24h water absorption rate ≤0.5%; Thermal weight loss at 400℃≤8%; And the axial compression fatigue life is up to 10 7 times, the load is 50% of the ultimate strength.

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