Preparation method and device of low-static polyacrylonitrile carbon fiber precursor

Abstract

The invention discloses a preparation method and device of a low-static polyacrylonitrile carbon fiber precursor, and belongs to the technical field of carbon fiber precursor preparation. The three working procedures of drying densification, static elimination and antistatic oiling are integrated in the same device, and the temperature is gradually increased from 90-140 DEG C and then is gradually reduced through a four-stage gradient drying roller, so that moisture in fibers is evaporated step by step, and the micropore defect caused by shock cooling and shock heating is avoided; fibers are preliminarily infiltrated in the pre-oiling groove, nanoscale dispersion of an oiling agent is achieved through 40 kHz ultrasonic vibration in the fine oiling groove, and the oil film thickness CV value is smaller than or equal to 8%; a compound system containing an anion-cation double antistatic agent and nano silicon dioxide is developed, the problem that a traditional single-component antistatic agent is insufficient in effect is solved, the oiling agent has instant static dissipation and lasting antistatic performance, alkyl sodium sulfonate is used for rapidly neutralizing positive charges, quaternary ammonium salt derivatives form a lasting conductive layer, and the antistatic effect of the oiling agent is improved. The nano silicon dioxide enhances the adhesive force of the oil film, and the surface resistance of the fiber is reduced from more than 1 * 10 < 12 > ohm to less than or equal to 1 * 10 < 10 > ohm through the synergism of the

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon fiber precursor preparation, and specifically relates to a method for preparing low-static polyacrylonitrile (PAN) carbon fiber precursor by using an integrated oiling and drying device, which solves the problems of static electricity accumulation, uneven oil distribution and low production efficiency in the drying process in traditional processes. Background Art

[0002] In the current field of carbon fiber precursor related technology, although the existing patents have achieved some results, there are still significant shortcomings.

[0003] In the production of carbon fiber precursor, the drying, densification and oiling process of polyacrylonitrile (PAN)-based precursor is a key link. Currently, the industry mainly adopts the following technical solutions:

[0004] ① Drying and densification technology

[0005] The traditional process uses a multi-roller dryer. For example, patent CN118996652A discloses a gradient temperature drying method, but it does not solve the static electricity problem caused by the friction between the fiber and the roller surface during the drying process. Some companies have tried to use hot air drying instead of contact drying, but it has the defects of high energy consumption and uneven drying (see "Research on Optimization of Carbon Fiber Precursor Drying Process", 2023).

[0006] ②Oil coating technology

[0007] Most existing oiling devices are independent units. For example, patent CN119640440A uses a multi-stage oiling tank, but does not consider the impact of static electricity accumulation on oil distribution during the oiling process. Conventional oiling agents are mainly for lubrication and have insufficient anti-static properties, which causes the fiber to easily absorb dust during subsequent processing, affecting the quality of the carbon fiber.

[0008] ③Static electricity control technology

[0009] A few companies install ionizing air bars before collecting the yarn, but these only eliminate surface static electricity and fail to address the root cause of static electricity during the drying process. Japan's Toray Industries patent (JP2022-052134) proposes adding an antistatic agent to the spinning solution, but this can affect the stability of the polymerization reaction.

[0010] Insufficient existing technology:

[0011] ①Hazards of static electricity

[0012] During the drying process, the surface potential of the fiber can reach ±3kV, resulting in increased fiber lint and breakage, and reduced production efficiency (statistics from one company show that static electricity causes an 8-12% drop in yield). Static electricity attracts dust particles, forming defects after carbonization, reducing the strength of the carbon fiber (see "Research on the Mechanism of Carbon Fiber Defect Formation," 2024).

[0013] ②Process disconnection

[0014] The drying and oiling processes operate independently, making it impossible to coordinately control static electricity and oil distribution, resulting in fluctuations in fiber properties. Traditional oiling agents tend to agglomerate in high static environments, resulting in uneven oil film thickness (CV value > 15%).

[0015] ③Equipment defects

[0016] The surface roughness of the existing drying roller is Ra ≥ 0.8μm, which increases the risk of triboelectric charging; the unreasonable structure of the oil nozzle leads to uneven oil injection pressure and excessive or insufficient oil in some areas. Summary of the Invention

[0017] The purpose of the present invention is to provide a method and device for preparing low-static polyacrylonitrile carbon fiber precursor, which solves the problems of the prior art by:

[0018] The above technical problems of the present invention are mainly solved by the following technical solutions: a method and device for preparing low-static polyacrylonitrile carbon fiber precursor, the device comprising a spinning unit, a coagulation unit, a washing unit, a drying and oiling integrated unit and a post-processing unit connected in sequence; the drying and oiling integrated unit comprises:

[0019] ① Multi-stage heating roller drying system: It consists of four-stage chrome-plated heating rollers, partitions, guide plates and guide rollers 13. The four-stage chrome-plated heating rollers are represented by P1, P2, P3 and P4 respectively. Partitions are set between P1, P2, P3 and P4. The first-stage heating roller P1 includes heating roller 1, heating roller 2 and heating roller 3. The second-stage heating roller P2 includes heating roller 4, heating roller 5 and heating roller 6. The third-stage heating roller P3 includes heating roller 7, heating roller 8 and heating roller 9. The fourth-stage heating roller P4 includes heating roller 10, heating roller 11 and heating roller 12. Each heating roller is independently temperature-controlled within the temperature range of 80-150°C. The linear speed difference between adjacent heating rollers is 0.5-2.0%, which is used for gradient drying of fibers and controlling fiber crystallinity.

[0020] ② Ion wind bar static elimination system: The discharge needle is set between the second-stage heating roller P2 and the third-stage heating roller P3. The ion wind bar has an operating voltage of ±7-9kV and a distance of 50-120mm from the fiber bundle. It is equipped with a non-contact surface potential sensor to monitor the fiber surface potential in real time.

[0021] ③ Double-tank oiling system: including pre-oiling tank and finishing oiling tank. The pre-oiling tank is equipped with guide roller 14, oiling roller 15, oiling roller 16, oiling roller 17, oiling roller 18, oiling roller 19, squeezing roller 20, guide roller 21 and magnetic stirrer. The finishing oiling tank is equipped with guide roller 22 and quick insert, guide roller 24, U-shaped porcelain parts, oil tank base and ultrasonic vibrator (frequency 30-50kHz, power 200-600W). The difference in oil concentration between the two tanks is 2-5%. The bottom of the pre-oiling tank is made of glass and the upper part is made of stainless steel. The bottom of the pre-oiling tank is equipped with a magnetic stirrer base.

[0022] ④ Closed-loop control system: The drying system, static elimination system and oiling system are connected through a PLC controller, and the wind speed of the ion wind bar, oiling rate and fiber tension are automatically adjusted according to the feedback from the surface potential sensor and 12 sets of tension sensors (accuracy ±0.5cN / dtex).

[0023] Preferably, the four-stage heating rollers (1-12) of the multi-stage heating roller drying system have a diameter of 300-500 mm and a length of 1200-1800 mm. They are made of 45 steel with a hard chrome plating (coating thickness 0.05-0.1 mm), with a surface roughness Ra ≤ 0.4 μm. Each heating roller is equipped with an independent temperature control system with a temperature fluctuation range of ±1°C. The guide roller 13 is made of the same material as the four-stage heating rollers (1-12), but has no heating function and only has a guiding function.

[0024] The ion wind rod of the ion wind rod static elimination system is a tungsten alloy discharge needle with a distance of 8 to 12 mm. The positive / negative ion concentration generated during operation is ≥1.0×106ions / cm 3 , the wind speed can be adjusted in the range of 3 to 8 m / s, the static neutralization rate is ≥1000 V / s, and the absolute value of the fiber surface potential is ≤±800 V;

[0025] The pre-oiling tank and the finishing oiling tank of the dual-tank oiling system are both equipped with a constant temperature circulation device with a temperature control accuracy of ±0.5°C. The pre-oiling tank adopts immersion oiling, and the finishing oiling tank adopts a spray-ultrasonic composite oiling method. The oil is delivered by a metering pump with a flow control accuracy of ±0.3%;

[0026] The antistatic oiling agent used in the double-tank oiling system includes the following components in percentage by mass:

[0027] Polyether-modified silicone oil 45-50%: As the basic lubricating component, the polyether segment accounts for 60-70% of its molecular structure, with a number average molecular weight of 8000-12000 and an HLB value of 12-14. It can form a lubricating film with a low friction coefficient (≤0.2) on the fiber surface;

[0028] Sodium alkyl sulfonate 12-15%: linear sodium alkyl sulfonate with 14-16 carbon atoms, purity ≥98%, critical micelle concentration (CMC) ≤0.03g / L, with rapid charge neutralization capability;

[0029] 8-10% quaternary ammonium salt derivative: selected from didodecyldimethylammonium chloride or hexadecyltrimethylammonium bromide, molecular weight 350-450, cationic group density ≥1.2mmol / g, forming a durable antistatic adsorption layer;

[0030] Fatty acid glyceride 20-25%: compounded from oleic acid glyceride (60-70%) and stearic acid glyceride (30-40%), with an iodine value of ≤25gI2 / 100g, to improve the compatibility of the oil and fiber;

[0031] Nano-silicon dioxide 3-5%: primary particle size 5-15nm, surface modified with γ-aminopropyltriethoxysilane, hydroxylation degree ≥95%, dispersibility in oil ≥98% (agglomerates with particle size >50nm ≤2%);

[0032] 1-2% antioxidant: selected from dilauryl thiodipropionate or tris(2,4-di-tert-butylphenyl) phosphite, melting point ≥ 70°C, thermal weight loss at 120°C ≤ 1%;

[0033] The surface tension of the antistatic oiling agent is 28-32 mN / m (measured at 25° C. by the hanging plate method), the kinematic viscosity is 15-20 cSt (measured at 40° C. by GB / T265 standard), and the conductivity is ≥50 μS / cm (measured at 25° C. by a DDS-307A conductivity meter).

[0034] Preferably, the surface modification treatment steps of the nano-silicon dioxide are as follows:

[0035] Nano-silica powder and a silane coupling agent were added to an ethanol aqueous solution (ethanol:water=3:1, volume ratio) in a mass ratio of 10:1, and the mixture was reacted at 60°C and 200 rpm under stirring for 3 hours. After filtration, the mixture was vacuum-dried at 100°C for 4 hours to obtain a modified nano-silica with a surface grafting rate of ≥85%, and a ratio of the Si-OC characteristic peak intensity at 1080 cm-1 to the Si-OH peak intensity at 960 cm-1 in its infrared spectrum of ≥1.5;

[0036] The polyether-modified silicone oil is an ethylene oxide (EO)-propylene oxide (PO) block copolymer, wherein the EO molar content is 65-70%, the PO molar content is 30-35%, the block ratio EO:PO=2:1 (molar ratio), and the density at 25°C is 0.95-1.05 g / cm 3 , can form a stable O / W emulsion with water (emulsion particle size ≤ 100nm).

[0037] Preferably, the compounding process of the components in the antistatic oiling agent is:

[0038] Polyether-modified silicone oil and fatty acid glyceride were melt-mixed at 50°C, nano-silica was added and ultrasonically dispersed for 30 minutes (power 300W, frequency 40kHz). After cooling to 30°C, sodium alkyl sulfonate, quaternary ammonium salt derivative and antioxidant were added in sequence, with a stirring speed of 150 rpm and a mixing time of 2 hours to obtain a uniform and transparent oil solution.

[0039] A method for preparing low-static polyacrylonitrile carbon fiber precursor, characterized by comprising the following steps:

[0040] (1) Preparation of spinning solution: Acrylonitrile and itaconic acid were dissolved in dimethyl sulfoxide (DMSO) at a mass ratio of 98:2 to prepare a solution with a solid content of 22%. 0.4 wt% azobisisobutyronitrile (AIBN) was added and polymerized at 65°C under nitrogen protection for 14 hours. After monomer removal and vacuum degassing, the solution was filtered through a 5 μm filter to obtain a spinning solution with a viscosity-average molecular weight of 130,000 and an intrinsic viscosity of 3.5 dL / g.

[0041] (2) Dry-jet wet spinning and coagulation: The spinning solution was extruded through a spinneret (aperture 50 μm, number of holes 24K) with an air layer height of 6 mm, and then entered into a coagulation bath of 35% DMSO aqueous solution (temperature 7°C). A three-stage coagulation and drawing process was performed, with the first-stage drawing ratio being 1.0, the second-stage drawing ratio being 1.35, and the third-stage drawing ratio being 1.5, to form a nascent fiber with an orientation degree ≥85%;

[0042] (3) Integrated drying and oiling treatment:

[0043] After being washed with warm water at 70°C (containing 0.5% deionized water), the spun fiber enters the drying unit with a tension of 12 cN / dtex. The temperatures of the four-stage heating rollers are 100°C, 120°C, 140°C, and 125°C, respectively. The residence time of each roller is 6s, 8s, 9s, and 7s, respectively, and the total drying time is 30s.

[0044] The ion wind bar eliminates static electricity in real time at a voltage of ±7.5kV and a wind speed of 6m / s. The surface potential sensor (accuracy ±50V) provides real-time feedback and automatically increases the wind speed by 10% when the potential is greater than +800V.

[0045] The concentration of the pre-oiling tank oil was 12% (45°C) and the fiber immersion time was 4 seconds. The concentration of the fine oiling tank oil was 15% (45°C) and the fiber immersion time was 2 seconds. The ultrasonic vibrator power was 450W (frequency 40kHz), and the atomized particle size of the oil was controlled to be ≤3μm. The oiling rate was controlled to be 1.0±0.1%.

[0046] (4) Post-processing molding: The dried and oiled fibers were stretched 1.2 times in 115°C, 0.35 MPa steam, and then heat-set at 170°C for 50 seconds to control the fiber shrinkage to ≤1.2%. Finally, they were wound at a tension of 7 cN / dtex to obtain low-static raw yarn with a linear density of 0.8 dtex and an oil content of 0.95%.

[0047] Preferably, the antistatic oiling agent is used at a temperature of 45-50°C, and the temperature is circulated and controlled by a plate heat exchanger with a temperature fluctuation of ±0.5°C to ensure that the viscosity of the oil is stable at 18±2 cSt (40°C) to achieve uniform coating;

[0048] The steam humidity of the steam drawing process in step (4) is ≥95%, and the drawing speed matches the drying unit outlet speed by ±1.0% to avoid fiber defects caused by sudden changes in fiber tension during the drawing process;

[0049] The demonification process of the spinning solution in step (1) adopts a vacuum flash evaporation method, the demonification temperature is 80-90°C, the vacuum degree is ≤-0.09MPa, the residual monomer content is ≤0.05wt%, the filtration accuracy of the spinning solution is 5μm, and the filter element material is sintered metal powder;

[0050] The concentration gradient of the coagulation bath in step (2) is as follows: the DMSO concentration in the first coagulation zone is 35-38% and the temperature is 5-8°C; the DMSO concentration in the second coagulation zone is 25-30% and the temperature is 10-15°C; the DMSO concentration in the third coagulation zone is 15-20% and the temperature is 15-20°C. The total residence time of the fiber in the coagulation bath is 40-60s.

[0051] The surface temperature distribution uniformity of the heating roller of the drying unit in step (3) is ≤±0.5°C, the tension fluctuation of the fiber during the drying process is ≤±0.5 cN / dtex, and the moisture content of the fiber after drying is ≤0.5 wt%;

[0052] The installation angle of the ion wind rod in step (3) is 45° to 60° with the direction of fiber running, and the distance deviation between the ion wind rod and the fiber bundle is ≤±5mm, ensuring that the uniformity of the static elimination effect is ≥95%;

[0053] The heat setting process described in step (4) is carried out in a three-stage hot air circulation box, with the temperature of the first section being 150-160°C, the temperature of the second section being 160-170°C, and the temperature of the third section being 170-180°C. The residence time of each section is 15-20s. The shrinkage rate of the fiber during the heat setting process is precisely controlled within a range of 0.8-1.2% by a tension control system.

[0054] Preferably, the performance indicators of the low-static polyacrylonitrile carbon fiber precursor are: linear density deviation rate ≤±2%, breaking strength ≥5.5cN / dtex, breaking elongation 10-12%; surface potential absolute value ≤±600V, friction coefficient ≤0.25, oil content 0.8-1.2%; single fiber diameter 6.5-7.5μm, cross-sectional profile ≤10%, and hair amount ≤0.5 pieces / 10,000m;

[0055] The surface is uniformly coated with 0.8-1.2 wt% of the antistatic oiling agent according to claim 4, the absolute value of the surface potential of the raw silk is ≤±600V, and after being placed in an environment with a relative humidity of 40-60% for 24 hours, the surface potential change rate is ≤±15%;

[0056] The internal structural characteristics of the precursor are: crystallinity of 40-50%, orientation degree ≥90%, skin-core structure difference ≤10%, cross-sectional circularity ≥95%, and coefficient of variation of friction coefficient between single fibers ≤5%;

[0057] The static electricity accumulation amount of the raw silk during the winding process is ≤±300V / m, the static electricity generation amount during the unwinding process is ≤±400V / m, and the flying waste content is ≤0.2mg / 10,000m at a winding speed of 100m / min.

[0058] Preferably, the PLC controller of the closed-loop control system adopts Siemens S7-1500 series, with a sampling frequency of ≥10 Hz, and a control algorithm adopts PID adaptive control. According to the real-time feedback of the fiber surface potential, oiling rate and drying temperature, the wind speed of the ion wind bar, the oil flow rate and the temperature of the heating roller are dynamically adjusted, and the control accuracy reaches: surface potential ±50V, oiling rate ±0.05%, temperature ±0.5°C, tension ±0.3 cN / dtex;

[0059] The spinneret of the spinning unit is made of high-strength stainless steel (such as 316L), the spinneret hole aspect ratio L / D = 2 to 3, the hole spacing is 0.8 to 1.2 mm, the spinneret surface roughness Ra ≤ 0.2 μm, and the spinneret assembly is equipped with an independent temperature control system with a temperature control accuracy of ±0.5°C;

[0060] The washing unit adopts a five-stage countercurrent washing structure, each washing tank is equipped with an ultrasonic vibrator (power 150-250W, frequency 28-40kHz), the washing water temperature gradient is: 40-50°C in the first stage, 50-60°C in the second stage, 60-70°C in the third stage, 70-80°C in the fourth stage, and 80-90°C in the fifth stage. The residual DMSO content in the fiber after washing is ≤0.1wt%;

[0061] The post-processing unit includes a steam drawing machine and a heat setting machine. The steam pressure control accuracy of the steam drawing machine is ±0.01MPa, the temperature control accuracy is ±1°C, the hot air speed of the heat setting machine is 3-5m / s, the temperature distribution uniformity is ≤±1°C, and the fiber tension fluctuation in the heat setting machine is ≤±0.5cN / dtex.

[0062] Preferably, the preparation method of the antistatic oiling agent comprises:

[0063] (1) Put polyether-modified silicone oil and fatty acid glyceride into a preparation kettle in proportion, and melt-mix them at 50-60° C. and 100-150 rpm for 30-60 minutes;

[0064] (2) Add nano-silica, turn on the ultrasonic dispersion device (power 300-500W, frequency 35-45kHz), and disperse at 40-50°C for 40-60 minutes;

[0065] (3) cooling to 30-35° C., adding sodium alkyl sulfonate, quaternary ammonium salt derivative, and antioxidant in sequence, and reacting for 1-2 hours under stirring at 150-200 rpm;

[0066] (4) Filter through a 10 μm filter element to obtain a uniform and transparent antistatic oiling agent with a particle size distribution D90 ≤ 5 μm and a stability (centrifugal separation at 3000 rpm for 30 minutes) stratification rate ≤ 1%.

[0067] Preferably, the low-static polyacrylonitrile carbon fiber precursor is pre-oxidized (200-300°C) and carbonized (1000-1500°C), and the performance indicators of the obtained carbon fiber are: single fiber diameter 5.5-6.5μm, density 1.75-1.80g / cm 3 ; Tensile strength ≥4.5GPa, tensile modulus ≥230GPa, elongation at break ≥1.8%; surface oxygen index (O / C) 0.08~0.12, hair content ≤1 piece / 10,000m, resistivity 1.5~1.8×10-3Ω·cm.

[0068] The present invention has the following beneficial effects: it integrates the three key processes of drying and densification, static elimination, and antistatic oiling into the same device. The four-stage gradient drying roller gradually increases and then decreases the temperature from 90-140°C, allowing the moisture inside the fiber to evaporate step by step, avoiding microporous defects caused by sudden cooling and heating. Ion wind rods are integrated above each stage of the drying roller, and combined with feedback from the surface potential sensor, the fiber surface potential is controlled within ±800V in real time. The pre-oiling tank initially soaks the fiber, and the fine oiling tank achieves nano-level dispersion of the oil agent through 40kHz ultrasonic vibration, with a CV value of the oil film thickness ≤8%.

[0069] A compound system containing "anionic-cationic dual antistatic agent + nano-silica" was developed to solve the problem of insufficient effect of traditional single-component antistatic agents, so that the oil agent has both instant static dissipation and lasting antistatic properties. Sodium alkyl sulfonate (anion) is used to quickly neutralize positive charges, quaternary ammonium salt derivatives (cation) form a lasting conductive layer, and nano-silica enhances the adhesion of the oil film. The three work together to reduce the surface resistance of the fiber from >1×10 12 Ω is reduced to ≤1×10 10 Ω;

[0070] Based on real-time feedback of the fiber surface potential, the drying temperature, ion wind rod parameters and oiling agent concentration are dynamically adjusted to form a "detection-feedback-adjustment" closed-loop system, breaking through the limitations of traditional fixed parameter control. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 This is a simplified diagram of the integrated drying and oiling device of the present invention;

[0072] Figure 2 This is a top view of the fine oil tank of the present invention;

[0073] Figure 3 It is the left side view of the fine oil tank of the present invention.

[0074] In the figure: 1, heating roller 1; 2, heating roller 2; 3, heating roller 3; 4, heating roller 4; 5, heating roller 5; 6, heating roller 6; 7, heating roller 7; 8, heating roller 8; 9, heating roller 9; 10, heating roller 10; 11, heating roller 11; 12, heating roller 12; 13, guide roller 13; 14, guide roller 14; 15, oiling roller 15; 16, oiling roller 16; 17, oiling roller 17; 18, oiling roller 18; 19, oiling roller 19; 20, squeezing roller 20; 21, guide roller 21; 22 , guide roller 22; 23, quick plug; 24, guide roller 24; 25, guide plate; 26, magnetic stirrer; 27, U-shaped porcelain piece; 28, oil tank base; 29, ultrasonic vibrator; 30, discharge needle; 31, partition; O1, pre-oiling tank; O2, fine oiling tank; I, multi-stage heating roller drying system; II, ion wind bar static elimination system; III, double-trough oiling system; IV, closed-loop control system; P1, first-stage drying roller group; P2, second-stage drying roller group; P3, third-stage drying roller group; P4, fourth-stage drying roller group. DETAILED DESCRIPTION

[0075] The technical solution of the present invention will be further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0076] Example: A method and device for preparing low-static polyacrylonitrile carbon fiber precursor, such as Figure 1-Figure 3As shown, the device includes a spinning unit, a coagulation unit, a washing unit, a drying and oiling integrated unit and a post-processing unit connected in sequence; the drying and oiling integrated unit includes:

[0077] ① Multi-stage heating roller drying system: It consists of four-stage chrome-plated heating rollers, partitions, guide plates and guide rollers 13. The four-stage chrome-plated heating rollers are represented by P1, P2, P3 and P4 respectively. Partitions are set between P1, P2, P3 and P4. The first-stage heating roller P1 includes heating roller 1, heating roller 2 and heating roller 3. The second-stage heating roller P2 includes heating roller 4, heating roller 5 and heating roller 6. The third-stage heating roller P3 includes heating roller 7, heating roller 8 and heating roller 9. The fourth-stage heating roller P4 includes heating roller 10, heating roller 11 and heating roller 12. Each heating roller is independently temperature-controlled within the temperature range of 80-150°C. The linear speed difference between adjacent heating rollers is 0.5-2.0%, which is used for gradient drying of fibers and controlling fiber crystallinity.

[0078] ② Ion wind bar static elimination system: The discharge needle is set between the second-stage heating roller P2 and the third-stage heating roller P3. The ion wind bar has an operating voltage of ±7-9kV and a distance of 50-120mm from the fiber bundle. It is equipped with a non-contact surface potential sensor to monitor the fiber surface potential in real time.

[0079] ③ Double-tank oiling system: including pre-oiling tank and finishing oiling tank. The pre-oiling tank is equipped with guide roller 14, oiling roller 15, oiling roller 16, oiling roller 17, oiling roller 18, oiling roller 19, squeezing roller 20, guide roller 21 and magnetic stirrer. The finishing oiling tank is equipped with guide roller 22 and quick insert, guide roller 24, U-shaped porcelain parts, oil tank base and ultrasonic vibrator (frequency 30-50kHz, power 200-600W). The difference in oil concentration between the two tanks is 2-5%. The bottom of the pre-oiling tank is made of glass and the upper part is made of stainless steel. The bottom of the pre-oiling tank is equipped with a magnetic stirrer base.

[0080] ④ Closed-loop control system: The drying system, static elimination system and oiling system are connected through a PLC controller, and the wind speed of the ion wind bar, oiling rate and fiber tension are automatically adjusted according to the feedback from the surface potential sensor and 12 sets of tension sensors (accuracy ±0.5cN / dtex).

[0081] The four-stage heating rollers (1-12) of the multi-stage heating roller drying system have a diameter of 300-500 mm and a length of 1200-1800 mm. They are made of 45 steel with a hard chrome plating (coating thickness 0.05-0.1 mm), with a surface roughness Ra ≤ 0.4 μm. Each heating roller is equipped with an independent temperature control system with a temperature fluctuation range of ±1°C. The guide roller 13 is made of the same material as the four-stage heating rollers (1-12), but has no heating function and only a guiding function.

[0082] The ion wind rod of the ion wind rod static elimination system is a tungsten alloy discharge needle with a distance of 8 to 12 mm. The positive / negative ion concentration generated during operation is ≥1.0×106ions / cm 3 , the wind speed can be adjusted in the range of 3 to 8 m / s, the static neutralization rate is ≥1000 V / s, and the absolute value of the fiber surface potential is ≤±800 V;

[0083] The pre-oiling tank and the finishing oiling tank of the dual-tank oiling system are both equipped with a constant temperature circulation device with a temperature control accuracy of ±0.5°C. The pre-oiling tank adopts immersion oiling, and the finishing oiling tank adopts a spray-ultrasonic composite oiling method. The oil is delivered by a metering pump with a flow control accuracy of ±0.3%;

[0084] The antistatic oiling agent used in the double-tank oiling system includes the following components in percentage by mass:

[0085] Polyether-modified silicone oil 45-50%: As the basic lubricating component, the polyether segment accounts for 60-70% of its molecular structure, with a number average molecular weight of 8000-12000 and an HLB value of 12-14. It can form a lubricating film with a low friction coefficient (≤0.2) on the fiber surface;

[0086] Sodium alkyl sulfonate 12-15%: linear sodium alkyl sulfonate with 14-16 carbon atoms, purity ≥98%, critical micelle concentration (CMC) ≤0.03g / L, with rapid charge neutralization capability;

[0087] 8-10% quaternary ammonium salt derivative: selected from didodecyldimethylammonium chloride or hexadecyltrimethylammonium bromide, molecular weight 350-450, cationic group density ≥1.2mmol / g, forming a durable antistatic adsorption layer;

[0088] Fatty acid glyceride 20-25%: compounded from oleic acid glyceride (60-70%) and stearic acid glyceride (30-40%), with an iodine value of ≤25gI2 / 100g, to improve the compatibility of the oil and fiber;

[0089] Nano-silicon dioxide 3-5%: primary particle size 5-15nm, surface modified with γ-aminopropyltriethoxysilane, hydroxylation degree ≥95%, dispersibility in oil ≥98% (agglomerates with particle size >50nm ≤2%);

[0090] 1-2% antioxidant: selected from dilauryl thiodipropionate or tris(2,4-di-tert-butylphenyl) phosphite, melting point ≥ 70°C, thermal weight loss at 120°C ≤ 1%;

[0091] The surface tension of the antistatic oiling agent is 28-32 mN / m (measured at 25° C. by the hanging plate method), the kinematic viscosity is 15-20 cSt (measured at 40° C. by GB / T265 standard), and the conductivity is ≥50 μS / cm (measured at 25° C. by a DDS-307A conductivity meter).

[0092] The surface modification treatment steps of the nano-silicon dioxide are as follows:

[0093] Nano-silica powder and a silane coupling agent were added to an ethanol aqueous solution (ethanol:water=3:1, volume ratio) in a mass ratio of 10:1, and the mixture was reacted at 60°C and 200 rpm under stirring for 3 hours. After filtration, the mixture was vacuum-dried at 100°C for 4 hours to obtain a modified nano-silica with a surface grafting rate of ≥85%, and a ratio of the Si-OC characteristic peak intensity at 1080 cm-1 to the Si-OH peak intensity at 960 cm-1 in its infrared spectrum of ≥1.5;

[0094] The polyether-modified silicone oil is an ethylene oxide (EO)-propylene oxide (PO) block copolymer, wherein the EO molar content is 65-70%, the PO molar content is 30-35%, the block ratio EO:PO=2:1 (molar ratio), and the density at 25°C is 0.95-1.05 g / cm 3 , can form a stable O / W emulsion with water (emulsion particle size ≤ 100nm).

[0095] The compounding process of each component in the antistatic oiling agent is:

[0096] Polyether-modified silicone oil and fatty acid glyceride were melt-mixed at 50°C, nano-silica was added and ultrasonically dispersed for 30 minutes (power 300W, frequency 40kHz). After cooling to 30°C, sodium alkyl sulfonate, quaternary ammonium salt derivative and antioxidant were added in sequence, with a stirring speed of 150 rpm and a mixing time of 2 hours to obtain a uniform and transparent oil solution.

[0097] A method for preparing low-static polyacrylonitrile carbon fiber precursor comprises the following steps:

[0098] (1) Preparation of spinning solution: Acrylonitrile and itaconic acid were dissolved in dimethyl sulfoxide (DMSO) at a mass ratio of 98:2 to prepare a solution with a solid content of 22%. 0.4 wt% azobisisobutyronitrile (AIBN) was added and polymerized at 65°C under nitrogen protection for 14 hours. After monomer removal and vacuum degassing, the solution was filtered through a 5 μm filter to obtain a spinning solution with a viscosity-average molecular weight of 130,000 and an intrinsic viscosity of 3.5 dL / g.

[0099] (2) Dry-jet wet spinning and coagulation: The spinning solution was extruded through a spinneret (aperture 50 μm, number of holes 24K) with an air layer height of 6 mm, and then entered into a coagulation bath of 35% DMSO aqueous solution (temperature 7°C). A three-stage coagulation and drawing process was performed, with the first-stage drawing ratio being 1.0, the second-stage drawing ratio being 1.35, and the third-stage drawing ratio being 1.5, to form a nascent fiber with an orientation degree ≥85%;

[0100] (3) Integrated drying and oiling treatment:

[0101] After being washed with warm water at 70°C (containing 0.5% deionized water), the spun fiber enters the drying unit with a tension of 12 cN / dtex. The temperatures of the four-stage heating rollers are 100°C, 120°C, 140°C, and 125°C, respectively. The residence time of each roller is 6s, 8s, 9s, and 7s, respectively, and the total drying time is 30s.

[0102] The ion wind bar eliminates static electricity in real time at a voltage of ±7.5kV and a wind speed of 6m / s. The surface potential sensor (accuracy ±50V) provides real-time feedback and automatically increases the wind speed by 10% when the potential is greater than +800V.

[0103] The concentration of the pre-oiling tank oil was 12% (45°C) and the fiber immersion time was 4 seconds. The concentration of the fine oiling tank oil was 15% (45°C) and the fiber immersion time was 2 seconds. The ultrasonic vibrator power was 450W (frequency 40kHz), and the atomized particle size of the oil was controlled to be ≤3μm. The oiling rate was controlled to be 1.0±0.1%.

[0104] (4) Post-processing molding: The dried and oiled fibers were stretched 1.2 times in 115°C, 0.35 MPa steam, and then heat-set at 170°C for 50 seconds to control the fiber shrinkage to ≤1.2%. Finally, they were wound at a tension of 7 cN / dtex to obtain low-static raw yarn with a linear density of 0.8 dtex and an oil content of 0.95%.

[0105] The operating temperature of the antistatic oiling agent is 45-50°C, and the temperature is circulated and controlled by a plate heat exchanger with a temperature fluctuation of ±0.5°C to ensure that the viscosity of the oil is stable at 18±2cSt (40°C) to achieve uniform coating;

[0106] The steam humidity of the steam drawing process in step (4) is ≥95%, and the drawing speed matches the drying unit outlet speed by ±1.0% to avoid fiber defects caused by sudden changes in fiber tension during the drawing process;

[0107] The demonification process of the spinning solution in step (1) adopts a vacuum flash evaporation method, the demonification temperature is 80-90°C, the vacuum degree is ≤-0.09MPa, the residual monomer content is ≤0.05wt%, the filtration accuracy of the spinning solution is 5μm, and the filter element material is sintered metal powder;

[0108] The concentration gradient of the coagulation bath in step (2) is as follows: the DMSO concentration in the first coagulation zone is 35-38% and the temperature is 5-8°C; the DMSO concentration in the second coagulation zone is 25-30% and the temperature is 10-15°C; the DMSO concentration in the third coagulation zone is 15-20% and the temperature is 15-20°C. The total residence time of the fiber in the coagulation bath is 40-60s.

[0109] The surface temperature distribution uniformity of the heating roller of the drying unit in step (3) is ≤±0.5°C, the tension fluctuation of the fiber during the drying process is ≤±0.5 cN / dtex, and the moisture content of the fiber after drying is ≤0.5 wt%;

[0110] The installation angle of the ion wind rod in step (3) is 45° to 60° with the direction of fiber running, and the distance deviation between the ion wind rod and the fiber bundle is ≤±5mm, ensuring that the uniformity of the static elimination effect is ≥95%;

[0111] The heat setting process described in step (4) is carried out in a three-stage hot air circulation box, with the temperature of the first section being 150-160°C, the temperature of the second section being 160-170°C, and the temperature of the third section being 170-180°C. The residence time of each section is 15-20s. The shrinkage rate of the fiber during the heat setting process is precisely controlled within a range of 0.8-1.2% by a tension control system.

[0112] The performance indicators of the low-static polyacrylonitrile carbon fiber precursor are: linear density deviation rate ≤±2%, breaking strength ≥5.5cN / dtex, breaking elongation 10-12%; surface potential absolute value ≤±600V, friction coefficient ≤0.25, oil content 0.8-1.2%; single fiber diameter 6.5-7.5μm, cross-sectional profile ≤10%, and fuzzy fiber content ≤0.5 strands / 10,000m;

[0113] The surface is uniformly coated with 0.8-1.2 wt% of the antistatic oiling agent according to claim 4, the absolute value of the surface potential of the raw silk is ≤±600V, and after being placed in an environment with a relative humidity of 40-60% for 24 hours, the surface potential change rate is ≤±15%;

[0114] The internal structural characteristics of the precursor are: crystallinity of 40-50%, orientation degree ≥90%, skin-core structure difference ≤10%, cross-sectional circularity ≥95%, and coefficient of variation of friction coefficient between single fibers ≤5%;

[0115] The static electricity accumulation amount of the raw silk during the winding process is ≤±300V / m, the static electricity generation amount during the unwinding process is ≤±400V / m, and the flying waste content is ≤0.2mg / 10,000m at a winding speed of 100m / min.

[0116] The PLC controller of the closed-loop control system adopts Siemens S7-1500 series, with a sampling frequency of ≥10Hz. The control algorithm adopts PID adaptive control. According to the real-time feedback of the fiber surface potential, oiling rate and drying temperature, the wind speed of the ion wind bar, the oil flow rate and the temperature of the heating roller are dynamically adjusted. The control accuracy reaches: surface potential ±50V, oiling rate ±0.05%, temperature ±0.5°C, tension ±0.3cN / dtex;

[0117] The spinneret of the spinning unit is made of high-strength stainless steel (such as 316L), the spinneret hole aspect ratio L / D = 2 to 3, the hole spacing is 0.8 to 1.2 mm, the spinneret surface roughness Ra ≤ 0.2 μm, and the spinneret assembly is equipped with an independent temperature control system with a temperature control accuracy of ±0.5°C;

[0118] The washing unit adopts a five-stage countercurrent washing structure, each washing tank is equipped with an ultrasonic vibrator (power 150-250W, frequency 28-40kHz), the washing water temperature gradient is: 40-50°C in the first stage, 50-60°C in the second stage, 60-70°C in the third stage, 70-80°C in the fourth stage, and 80-90°C in the fifth stage. The residual DMSO content in the fiber after washing is ≤0.1wt%;

[0119] The post-processing unit includes a steam drawing machine and a heat setting machine. The steam pressure control accuracy of the steam drawing machine is ±0.01MPa, the temperature control accuracy is ±1°C, the hot air speed of the heat setting machine is 3-5m / s, the temperature distribution uniformity is ≤±1°C, and the fiber tension fluctuation in the heat setting machine is ≤±0.5cN / dtex.

[0120] The preparation method of the antistatic oiling agent comprises:

[0121] (1) Put polyether-modified silicone oil and fatty acid glyceride into a preparation kettle in proportion, and melt-mix them at 50-60° C. and 100-150 rpm for 30-60 minutes;

[0122] (2) Add nano-silica, turn on the ultrasonic dispersion device (power 300-500W, frequency 35-45kHz), and disperse at 40-50°C for 40-60 minutes;

[0123] (3) cooling to 30-35° C., adding sodium alkyl sulfonate, quaternary ammonium salt derivative, and antioxidant in sequence, and reacting for 1-2 hours under stirring at 150-200 rpm;

[0124] (4) Filter through a 10 μm filter element to obtain a uniform and transparent antistatic oiling agent with a particle size distribution D90 ≤ 5 μm and a stability (centrifugal separation at 3000 rpm for 30 minutes) stratification rate ≤ 1%.

[0125] The preparation method according to claim 9 is characterized in that: after the low-static polyacrylonitrile carbon fiber precursor is pre-oxidized (200-300°C) and carbonized (1000-1500°C), the performance indicators of the obtained carbon fiber are: single fiber diameter 5.5-6.5 μm, density 1.75-1.80 g / cm 3 ; Tensile strength ≥4.5GPa, tensile modulus ≥230GPa, elongation at break ≥1.8%; surface oxygen index (O / C) 0.08~0.12, hair content ≤1 piece / 10,000m, resistivity 1.5~1.8×10-3Ω·cm.

[0126] Example 1:

[0127] Preparation of spinning solution: 98 kg of acrylonitrile and 2 kg of itaconic acid were added to a 1000 L reactor. Dimethyl sulfoxide was added until the solid content of the solution reached 22%. After stirring and dissolving, 0.4 kg of azobisisobutyronitrile was added. Polymerization was carried out at 65°C under nitrogen for 14 hours. After completion of polymerization, the monomers were removed by vacuum flash evaporation, and the solution was then vacuum degassed and filtered through a 5 μm filter to obtain the spinning solution.

[0128] Wet spinning and coagulation: The spinning solution was extruded through a spinneret (50 μm pore size, 24K holes) with an air layer height of 6 mm and then entered a coagulation bath containing a 35% DMSO aqueous solution (7°C). In the coagulation bath, a three-stage coagulation and drawing process was performed, with a first-stage draw ratio of 1.0, a second-stage draw ratio of 1.35, and a third-stage draw ratio of 1.5, to form nascent fibers.

[0129] Integrated dry oiling:

[0130] After being washed with warm water at 70°C, the spun fibers enter the drying unit at a tension of 12 cN / dtex. The four-stage heating rollers are heated at 100°C, 120°C, 140°C, and 125°C, with dwell times of 6s, 8s, 9s, and 7s, respectively, for a total drying time of 30s.

[0131] The ionizing wind bar operates at ±7.5kV and a wind speed of 6m / s, eliminating static electricity in real time. A surface potential sensor monitors the fiber surface potential and automatically increases the wind speed by 10% when the potential exceeds +800V.

[0132] The concentration of the pre-oiling tank oil agent is 12% (45° C.), and the fiber immersion time is 4 s; the power of the fine oiling tank ultrasonic vibrator is 450 W (frequency 40 kHz), and the oiling rate is controlled at 1.0±0.1%.

[0133] Post-processing molding: The dried and oiled fiber was stretched 1.2 times in 115℃, 0.35MPa steam, and then heat-set at 170℃ for 50s to control the fiber shrinkage rate to ≤1.2%. Finally, it was wound with a tension of 7cN / dtex to obtain low-static polyacrylonitrile carbon fiber precursor.

[0134] Example 2:

[0135] Preparation of spinning solution: the same as in Example 1.

[0136] Wet spinning and coagulation: same as in Example 1.

[0137] Integrated dry oiling:

[0138] After being washed with warm water at 70°C, the spun fibers enter the drying unit at a tension of 12 cN / dtex. The four-stage heating rollers are set at temperatures of 105°C, 125°C, 145°C, and 130°C, with dwell times of 7s, 9s, 10s, and 8s, respectively, for a total drying time of 34s.

[0139] The ionizing wind bar operates at ±7.5kV and a wind speed of 6.5m / s, eliminating static electricity in real time. A surface potential sensor monitors the fiber surface potential and automatically increases the wind speed by 10% when the potential exceeds +800V.

[0140] The concentration of the pre-oiling tank oil agent is 13% (45° C.), and the fiber immersion time is 4.5 s; the power of the fine oiling tank ultrasonic vibrator is 450 W (frequency 40 kHz), and the oiling rate is controlled at 1.0±0.1%.

[0141] Post-processing molding: the same as Example 1.

[0142] Comparative Example 1 (Traditional polyacrylonitrile carbon fiber precursor preparation process):

[0143] Key parameters:

[0144] Drying method: single-stage heating roller (constant temperature 135℃), no gradient control;

[0145] Static control: ion-free wind rod and surface potential monitoring;

[0146] Oiling agent: ordinary silicone oil emulsion (without antistatic ingredients), single tank immersion oiling, no ultrasonic assistance;

[0147] Equipment maintenance: Manually clean the drying roller regularly (due to static electricity causing fiber adhesion).

[0148] The performance comparison test of the embodiment and the comparative example is shown in Table 2:

[0149] Table 2

[0150]

[0151] Comparative analysis:

[0152] Static control performance:

[0153] Due to the lack of active static electricity elimination measures, the surface potential of the comparative example is as high as ±2200V, resulting in significant electrostatic repulsion between fibers, and the number of lint is 3.75 times that of the embodiment; the present invention cooperates with gradient drying and ion wind rods, and the surface potential of 1 / 2 of the embodiment is stabilized within ±600V, suppressing the lint and breakage problems caused by static electricity from the source.

[0154] Quality stability:

[0155] In the comparative example, single-stage drying leads to uneven stress inside the fiber, with a linear density CV value of 1.8%. The oil agent agglomerates due to the lack of ultrasonic dispersion, and the distribution CV value is 18%. In the present invention, through double-slot ultrasonic oiling and gradient drying, the oil agent distribution CV value is reduced to below 7.5%, and the linear density CV value is ≤0.85%, reflecting excellent uniformity.

[0156] Production efficiency and cost:

[0157] In the comparative example, the drying roller needs to be cleaned eight times a week due to electrostatic adhesion, resulting in high maintenance costs. The maintenance frequency of the equipment of the present invention is reduced to less than once a week. Combined with a 25% reduction in the amount of antistatic agent used, the production cost is reduced by 14% to 17%.

[0158] Core advantage attribution:

[0159] Integrated device: gradient drying rollers reduce internal fiber defects, ion wind rods neutralize charges in real time, and double-slot ultrasonic oiling achieves nano-level dispersion of the oil; antistatic oil: polyether silicone oil is compounded with anionic and cationic antistatic agents to form a "fast conductivity-long-lasting protection" network, and nano-silicon dioxide enhances the adhesion of the oil film.

[0160] Through the above detailed examples and comparative examples, we can clearly see the significant effect of the present invention in improving performance and the importance of each process step.

[0161] The present invention provides a method and apparatus for preparing low-static polyacrylonitrile carbon fiber precursor. By optimizing the device structure and process parameters and combining it with a specific antistatic oiling agent, the surface potential of the precursor is effectively reduced, thereby improving the quality and performance of the precursor. Through the synergistic effect of "equipment structure innovation + antistatic oiling agent + closed-loop control", it is significantly superior to traditional processes in key indicators such as static control, quality stability, and production efficiency. It is particularly suitable for the preparation of high-end carbon fiber precursors that are sensitive to static electricity, and has significant technological progress and economic value. The method and apparatus have the advantages of stable process, high production efficiency, and excellent product performance. They are suitable for large-scale industrial production and have broad application prospects.

[0162] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and is susceptible to numerous variations. Any simple modifications, equivalent variations, and modifications to the above embodiments based on the technical essence of the present invention are deemed to fall within the scope of protection of the present invention.

Claims

1. A device for preparing low-static polyacrylonitrile carbon fiber precursor, characterized by: The device comprises a spinning unit, a coagulation unit, a washing unit, a drying and oiling integrated unit and a post-processing unit connected in sequence; the drying and oiling integrated unit comprises: ① Multi-stage heating roller drying system (Ⅰ): It consists of four-stage surface chrome-plated heating rollers, partitions and guide plates (25) and guide rollers 13 (13). The four-stage surface chrome-plated heating rollers are represented by P1, P2, P3 and P4 respectively. The partitions are arranged between P1, P2, P3 and P4. The first-stage heating roller P1 includes heating roller 1 (1), heating roller 2 (2) and heating roller 3 (3). The second-stage heating roller P2 includes heating roller 4 (4), heating roller 5 (5) and heating roller 6 (6). The third-stage heating roller P3 includes heating roller 7 (7), heating roller 8 (8) and heating roller 9 (9). The fourth-stage heating roller P4 includes heating roller 10 (10), heating roller 11 (11) and heating roller 12 (12). Each heating roller is independently temperature-controlled, with a temperature range of 80 to 150°C. The linear speed difference between adjacent heating rollers is 0.5 to 2.0%, which is used for gradient drying of fibers and controlling fiber crystallinity. ② Ion wind bar static elimination system (II): The discharge needle (30) is set between the second-stage heating roller P2 and the third-stage heating roller P3. The ion wind bar has an operating voltage of ±7-9kV and a distance of 50-120mm from the fiber bundle. It is equipped with a non-contact surface potential sensor to monitor the fiber surface potential in real time. ③ Double-tank oiling system (Ⅲ): including a pre-oiling tank (O1) and a fine oiling tank (O2), the pre-oiling tank (O1) is equipped with a guide roller 14 (14), an oiling roller 15 (15), an oiling roller 16 (16), an oiling roller 17 (17), an oiling roller 18 (18), an oiling roller 19 (19), an extrusion roller 20 (20), a guide roller 21 (21) and a magnetic stirrer (26), the fine oiling tank (O2) is equipped with a guide roller 22 (22) and a quick insert (23), a guide roller 24 (24), a U-shaped porcelain piece (27), an oil tank base (28) and an ultrasonic vibrator (29) (frequency 30-50kHz, power 200-600W), and the difference in oil concentration between the two tanks is 2-5%; the bottom of the pre-oiling tank (O1) is made of glass and the upper part is made of stainless steel, and a magnetic stirrer base is provided below the bottom of the pre-oiling tank (O1); ④ Closed-loop control system (IV): The drying system (I), static elimination system (II) and oiling system (III) are connected through a PLC controller, and the wind speed of the ion wind bar, oiling rate and fiber tension are automatically adjusted according to the feedback from the surface potential sensor and 12 sets of tension sensors.

2. The preparation device according to claim 1, characterized in that: The four-stage heating rollers (1-12) of the multi-stage heating roller drying system (I) have a diameter of 300-500 mm and a length of 1200-1800 mm. They are made of 45 steel with a hard chrome plating layer of 0.05-0.1 mm in thickness and a surface roughness of Ra ≤ 0.4 μm. Each heating roller is equipped with an independent temperature control system with a temperature fluctuation range of ±1°C. The guide roller (13) is made of the same material as the four-stage heating roller, but has no heating function and only a guiding function. The ion wind bar static elimination system (II) comprises a tungsten alloy discharge needle (30) with a discharge needle spacing of 8 to 12 mm. The positive / negative ion concentration generated during operation is ≥1.0×106 ions / cm 3 , the wind speed can be adjusted in the range of 3 to 8 m / s, the static neutralization rate is ≥1000 V / s, and the absolute value of the fiber surface potential is ≤±800 V; The pre-oiling tank (O1) and the finishing oiling tank (O2) of the double-tank oiling system (III) are both equipped with a constant temperature circulation device with a temperature control accuracy of ±0.5°C. The pre-oiling tank (O1) adopts an immersion oiling method, and the finishing oiling tank (O2) adopts a spray-ultrasonic composite oiling method. The oil is delivered by a metering pump with a flow control accuracy of ±0.3%; The antistatic oiling agent used in the double-tank oiling system (III) includes the following components in percentage by mass: Polyether-modified silicone oil 45-50%: As the basic lubricating component, its molecular structure contains 60-70% polyether segments, with a number average molecular weight of 8,000-12,000 and an HLB value of 12-14. It can form a lubricating film with a low friction coefficient of ≤0.2 on the fiber surface. Sodium alkyl sulfonate 12-15%: linear sodium alkyl sulfonate with 14-16 carbon atoms, purity ≥98%, critical micelle concentration (CMC) ≤0.03g / L, with rapid charge neutralization capability; 8-10% quaternary ammonium salt derivative: selected from didodecyldimethylammonium chloride or hexadecyltrimethylammonium bromide, molecular weight 350-450, cationic group density ≥1.2mmol / g, forming a durable antistatic adsorption layer; Fatty acid glyceride 20-25%: compounded from 60-70% oleic acid glyceride and 30-40% stearic acid glyceride, with an iodine value of ≤25gI2 / 100g, to improve the compatibility of the oil and fiber; Nano-silica 3-5%: primary particle size 5-15nm, surface modified with γ-aminopropyltriethoxysilane, hydroxylation degree ≥95%, dispersibility in oil ≥98%, agglomerates with particle size >50nm ≤2%; 1-2% antioxidant: selected from dilauryl thiodipropionate or tris(2,4-di-tert-butylphenyl) phosphite, melting point ≥ 70°C, thermal weight loss at 120°C ≤ 1%; The antistatic oiling agent has a surface tension of 28 to 32 mN / m, a kinematic viscosity of 15 to 20 cSt, and an electrical conductivity of ≥50 μS / cm.

3. The preparation device according to claim 2, characterized in that: The surface modification treatment steps of the nano-silicon dioxide are as follows: Nano-silica powder and silane coupling agent were added to ethanol aqueous solution at a mass ratio of 10:1, ethanol: water = 3:1, and reacted at 60 ° C and 200 rpm under stirring conditions for 3 hours. After filtration, it was vacuum-dried at 100 ° C for 4 hours to obtain modified nano-silica with a surface grafting rate of ≥85%. Its infrared spectrum showed that the surface grafting rate at 1080 cm -1 The Si-OC characteristic peak intensity at 960 cm -1 The Si-OH peak intensity ratio at ≥1.5; The polyether-modified silicone oil is an ethylene oxide (EO)-propylene oxide (PO) block copolymer, wherein the EO molar content is 65-70%, the PO molar content is 30-35%, the block ratio EO:PO=2:1 (molar ratio), and the density at 25°C is 0.95-1.05 g / cm 3 , can form a stable O / W emulsion with water, and the emulsion particle size is ≤100nm.

4. The preparation device according to claim 2, characterized in that: The compounding process of each component in the antistatic oiling agent is: Polyether-modified silicone oil and fatty acid glyceride were melt-mixed at 50°C, nano-silica was added and ultrasonically dispersed for 30 minutes, and sodium alkyl sulfonate, quaternary ammonium salt derivative and antioxidant were added in sequence after cooling to 30°C. The stirring speed was 150 rpm and the mixing time was 2 hours to obtain a uniform and transparent oil solution.

5. A method for preparing low-static polyacrylonitrile carbon fiber precursor using the device according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Preparation of spinning solution: Acrylonitrile and itaconic acid were dissolved in dimethyl sulfoxide (DMSO) at a mass ratio of 98:2 to prepare a solution with a solid content of 22%. 0.4 wt% azobisisobutyronitrile (AIBN) was added and polymerized at 65°C under nitrogen protection for 14 hours. After monomer removal and vacuum degassing, the solution was filtered through a 5 μm filter to obtain a spinning solution with a viscosity-average molecular weight of 130,000 and an intrinsic viscosity of 3.5 dL / g. (2) Dry-jet wet spinning and coagulation: The spinning solution is extruded through a spinneret with an air layer height of 6 mm and then enters a coagulation bath of 35% DMSO aqueous solution at a temperature of 7°C. A three-stage coagulation and drawing process is performed, with the first-stage drawing ratio being 1.0, the second-stage drawing ratio being 1.35, and the third-stage drawing ratio being 1.5, to form a nascent fiber with an orientation degree ≥ 85%; (3) Integrated drying and oiling treatment: After being washed with 0.5% deionized water at 70°C, the spun fibers were fed into the drying unit with a tension of 12 cN / dtex. The temperatures of the four-stage heating rollers were 100°C, 120°C, 140°C, and 125°C, respectively. The residence time of each roller was 6s, 8s, 9s, and 7s, respectively, for a total drying time of 30s. The ion wind bar eliminates static electricity in real time at a voltage of ±7.5kV and a wind speed of 6m / s. The surface potential sensor (accuracy ±50V) provides real-time feedback and automatically increases the wind speed by 10% when the potential is greater than +800V. The pre-oiling tank oil concentration is 12%, the temperature is 45°C, and the fiber immersion time is 4s; the fine oiling tank oil concentration is 15%, the temperature is 45°C, and the fiber immersion time is 2s. The ultrasonic vibrator power is 450W and the frequency is 40kHz. The oil atomization particle size is ≤3μm and the oiling rate is controlled at 1.0±0.1%. (4) Post-processing molding: The dried and oiled fibers were stretched 1.2 times in 115°C, 0.35 MPa steam, and then heat-set at 170°C for 50 seconds to control the fiber shrinkage to ≤1.2%. Finally, they were wound at a tension of 7 cN / dtex to obtain low-static raw yarn with a linear density of 0.8 dtex and an oil content of 0.95%.

6. The preparation method according to claim 4, characterized in that: The operating temperature of the antistatic oiling agent is 45-50°C, and the temperature is circulated and controlled by a plate heat exchanger with a temperature fluctuation of ±0.5°C to ensure that the viscosity of the oil is stable at 18±2cSt (40°C) to achieve uniform coating; The steam humidity of the steam drawing process in step (4) is ≥95%, and the drawing speed matches the drying unit outlet speed by ±1.0% to avoid fiber defects caused by sudden changes in fiber tension during the drawing process; The demonification process of the spinning solution in step (1) adopts a vacuum flash evaporation method, the demonification temperature is 80-90°C, the vacuum degree is ≤-0.09MPa, the residual monomer content is ≤0.05wt%, the filtration accuracy of the spinning solution is 5μm, and the filter element material is sintered metal powder; The concentration gradient of the coagulation bath in step (2) is as follows: the DMSO concentration in the first coagulation zone is 35-38% and the temperature is 5-8°C; the DMSO concentration in the second coagulation zone is 25-30% and the temperature is 10-15°C; the DMSO concentration in the third coagulation zone is 15-20% and the temperature is 15-20°C. The total residence time of the fiber in the coagulation bath is 40-60s. The surface temperature distribution uniformity of the heating roller of the drying unit in step (3) is ≤±0.5°C, the tension fluctuation of the fiber during the drying process is ≤±0.5 cN / dtex, and the moisture content of the fiber after drying is ≤0.5 wt%; The installation angle of the ion wind rod in step (3) is 45° to 60° with the direction of fiber running, and the distance deviation between the ion wind rod and the fiber bundle is ≤±5mm, ensuring that the uniformity of the static elimination effect is ≥95%; The heat setting process described in step (4) is carried out in a three-stage hot air circulation box, with the temperature of the first section being 150-160°C, the temperature of the second section being 160-170°C, and the temperature of the third section being 170-180°C. The residence time of each section is 15-20s. The shrinkage rate of the fiber during the heat setting process is precisely controlled within a range of 0.8-1.2% by a tension control system.

7. The preparation method according to claim 5, characterized in that: The performance indicators of the low-static polyacrylonitrile carbon fiber precursor are: linear density deviation rate ≤±2%, breaking strength ≥5.5cN / dtex, breaking elongation 10-12%; surface potential absolute value ≤±600V, friction coefficient ≤0.25, oil content 0.8-1.2%; single fiber diameter 6.5-7.5μm, cross-sectional profile ≤10%, and fuzzy fiber content ≤0.5 strands / 10,000m; The surface is uniformly coated with 0.8-1.2 wt% of the antistatic oiling agent according to claim 4, the absolute value of the surface potential of the raw silk is ≤±600V, and after being placed in an environment with a relative humidity of 40-60% for 24 hours, the surface potential change rate is ≤±15%; The internal structural characteristics of the precursor are: crystallinity of 40-50%, orientation degree ≥90%, skin-core structure difference ≤10%, cross-sectional circularity ≥95%, and coefficient of variation of friction coefficient between single fibers ≤5%; The static electricity accumulation amount of the raw silk during the winding process is ≤±300V / m, the static electricity generation amount during the unwinding process is ≤±400V / m, and the flying waste content is ≤0.2mg / 10,000m at a winding speed of 100m / min.

8. The preparation device according to claim 4, characterized in that: The PLC controller of the closed-loop control system adopts Siemens S7-1500 series, with a sampling frequency of ≥10Hz. The control algorithm adopts PID adaptive control. According to the real-time feedback of the fiber surface potential, oiling rate and drying temperature, the wind speed of the ion wind bar, the oil flow rate and the temperature of the heating roller are dynamically adjusted. The control accuracy reaches: surface potential ±50V, oiling rate ±0.05%, temperature ±0.5°C, tension ±0.3cN / dtex; The spinneret of the spinning unit is made of high-strength stainless steel (such as 316L), the spinneret hole aspect ratio L / D = 2 to 3, the hole spacing is 0.8 to 1.2 mm, the spinneret surface roughness Ra ≤ 0.2 μm, and the spinneret assembly is equipped with an independent temperature control system with a temperature control accuracy of ±0.5°C; The washing unit adopts a five-stage countercurrent washing structure, each washing tank is equipped with an ultrasonic vibrator (power 150-250W, frequency 28-40kHz), the washing water temperature gradient is: 40-50°C in the first stage, 50-60°C in the second stage, 60-70°C in the third stage, 70-80°C in the fourth stage, and 80-90°C in the fifth stage. The residual DMSO content in the fiber after washing is ≤0.1wt%; The post-processing unit includes a steam drawing machine and a heat setting machine. The steam pressure control accuracy of the steam drawing machine is ±0.01MPa, the temperature control accuracy is ±1°C, the hot air speed of the heat setting machine is 3-5m / s, the temperature distribution uniformity is ≤±1°C, and the fiber tension fluctuation in the heat setting machine is ≤±0.5cN / dtex.

9. The antistatic oiling agent according to claim 6, characterized in that: The preparation method of the antistatic oiling agent comprises: (1) Put polyether-modified silicone oil and fatty acid glyceride into a preparation kettle in proportion, and melt-mix them at 50-60° C. and 100-150 rpm for 30-60 minutes; (2) Add nano-silica, turn on the ultrasonic dispersion device (power 300-500W, frequency 35-45kHz), and disperse at 40-50°C for 40-60 minutes; (3) cooling to 30-35° C., adding sodium alkyl sulfonate, quaternary ammonium salt derivative, and antioxidant in sequence, and reacting for 1-2 hours under stirring at 150-200 rpm; (4) Filter through a 10 μm filter element to obtain a uniform and transparent antistatic oiling agent with a particle size distribution D90 ≤ 5 μm and a stability (centrifugal separation at 3000 rpm for 30 minutes) stratification rate ≤ 1%.

10. The preparation method according to claim 9, characterized in that: The low-static polyacrylonitrile carbon fiber precursor is pre-oxidized (200-300°C) and carbonized (1000-1500°C). The performance indicators of the obtained carbon fiber are: single fiber diameter 5.5-6.5μm, density 1.75-1.80g / cm 3 ; Tensile strength ≥4.5GPa, tensile modulus ≥230GPa, elongation at break ≥1.8%; surface oxygen index (O / C) 0.08~0.12, hair content ≤1 piece / 10,000m, resistivity 1.5~1.8×10-3Ω·cm.

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