High-performance fully-drawn polyester fiber and preparation device thereof

Abstract

The invention discloses a high-performance fully-drawn polyester fiber and a preparation device thereof, and relates to the technical field of synthetic fiber manufacturing, and the fiber is prepared from the following raw materials by mass: 98.2-98.8% of terephthalic acid and ethylene glycol copolymerized polyester; 1.2%-1.8% of a nano calcium carbonate modifier; 0.15%-0.2% of a delustering agent titanium dioxide; according to the method, 98.5% of dispersity of nano calcium carbonate is achieved through dynamic mixing screw design, the spinning end breakage rate is reduced to 0.4 times per thousand ingot hours in combination with an online viscosity monitoring system, and the fiber diameter CV value is optimized to 1.0%; the crystallinity of the fiber is improved to 55% through a gradient drafting device, the breaking strength reaches 6.3 cN / dtex, and the boiling water shrinkage rate is 3.0%; meanwhile, the bio-based copolymer is introduced for modification to improve the degradation rate, and the modular spinning assembly and the antistatic coating are combined, so that the production efficiency is improved, and meanwhile, the environment-friendly and multifunctional application scenarios are expanded.

Description

Technical Field

[0001] The invention relates to the technical field of synthetic fiber manufacturing, in particular to a high-performance fully drawn polyester fiber and a preparation device thereof. Background Art

[0002] In the field of synthetic fiber manufacturing, polyester fiber is widely used due to its low cost and high strength. However, the existing technology has the following prominent problems: Low dispersion efficiency of nano-modifiers: The traditional screw extruder 4 has insufficient dispersion of additives such as nano-calcium carbonate (≤90%), resulting in uneven melt flow resistance, a spinning breakage rate of more than 2 times / 1,000 spindle hours, and a fiber diameter deviation (CV value) of ≥2.0%, affecting product quality stability.

[0003] The control of process parameters is lagging: there is a lack of real-time viscosity monitoring means, the melt viscosity fluctuates by more than ±5%, the fiber crystallinity (≤50%) and orientation degree (≤0.85) are difficult to coordinately optimize, and the mechanical properties are limited (breaking strength ≤5.0cN / dtex, boiling water shrinkage ≥6.0%).

[0004] Insufficient functional expansion: Conventional polyester fibers are difficult to balance high strength, low shrinkage and environmental protection, and lack composite functions such as antistatic and biodegradability, and cannot meet the special needs of high-end textile, electronics and medical fields.

[0005] The root causes of the above problems lie in the design defects of mixing equipment, the lag in process parameter control and the inadequacy of functional modification technology, which lead to bottlenecks in the performance, stability and environmental protection of existing polyester fibers.

[0006] In view of this, a high-performance fully drawn polyester fiber and a preparation device thereof are provided to overcome the above problems. Summary of the invention

[0007] The object of the present invention is to provide a high-performance fully drawn polyester fiber to solve the problems of low dispersion efficiency, low stability and poor environmental performance of the existing polyester fiber nano-modifiers mentioned in the above background technology.

[0008] Another object of the present invention is to provide a preparation device.

[0009] In order to solve the above technical problems, the present invention provides a high-performance fully drawn polyester fiber, which is made of the following raw materials by mass fraction: Terephthalic acid and ethylene glycol copolymer polyester: 98.2%-98.8%; Nano calcium carbonate modifier: 1.2%-1.8%; Matting agent titanium dioxide: 0.15%-0.2%; The breaking strength of the fiber is ≥6.0cN / dtex, the boiling water shrinkage is ≤3.5%, and the diameter CV value is ≤1.2%.

[0010] Furthermore, the surface of the nano calcium carbonate is treated with a silane coupling agent, the particle size is 50-80 nm, and the dispersion degree in the polyester melt is ≥98%.

[0011] Furthermore, the fiber also contains 5%-15% by weight of a bio-based copolymer for degradation.

[0012] Furthermore, the fiber surface is coated with a silicon dioxide-graphene composite layer with a surface resistivity of ≤10 9 Ω, used for anti-static.

[0013] Furthermore, the fiber has a core-shell structure, the core layer is high-strength polyester, and the skin layer is polylactic acid, which is used to absorb medical materials.

[0014] A preparation device for high-performance fully drawn polyester fiber, comprising: Dynamic mixing screw extrusion system: The screw length-diameter ratio is 40:1, the compression ratio is 3.5:1, the screw groove depth gradually changes from 12mm in the feed section to 6mm in the metering section, and there are 3 sets of staggered tooth shear elements; Online viscosity monitoring system: including ultrasonic sensors in the melt pipe and linked screw speed / temperature control modules; Gradient drafting device: includes a double hot roller set with a temperature gradient of 65-135℃ and a dynamic tension adjustment component.

[0015] Furthermore, the screw channel structure was optimized through CFD simulation, and the Reynolds number Re>10 in the shear element area 4 .

[0016] Furthermore, the online viscosity monitoring system controls the melt viscosity in real time through the sonic velocity-viscosity model, with a fluctuation range of ≤±2%.

[0017] Furthermore, the speed ratio of the dual hot rollers of the gradient drawing device is 1:1.8-1:2.0, and the temperature of the second hot roller is 115-135°C.

[0018] Furthermore, it also includes: Infrared radiation heating zone, set in the spinning tunnel, with a temperature of 120-150°C, is used to induce pre-crystallization; Modular spinneret assembly supports quick replacement of 6-12 hole special-shaped spinnerets.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. Nano-dispersion and melt uniformity improvement Screw: The combination of a 40:1 aspect ratio and staggered toothed shear elements, combined with CFD simulation optimization, enables the dispersion of nano-calcium carbonate to reach 98.5%, the standard deviation of the melt flow index to be reduced by 58%, and the spinning breakage rate to be reduced to 0.4 times / 1,000 spindle hours.

[0020] Online viscosity monitoring: Based on the sonic velocity-viscosity model, the melt viscosity is regulated in real time, the fluctuation is controlled within ±2%, and the fiber diameter CV value is optimized to 1.0%, which is better than the industry standard.

[0021] 2. Breakthrough in fiber performance Mechanical properties: The breaking strength reaches 6.3cN / dtex, which is 31% higher than the traditional process; the boiling water shrinkage rate is 3.0%, which is 54% lower, meeting the requirements of high-end fields for dimensional stability.

[0022] Structural regulation: The gradient drafting device increases the fiber crystallinity to 55%, the orientation degree to 0.92, and the initial modulus to 120 cN / dtex.

[0023] 3. Collaborative optimization of process and environmental protection Clean production: titanium composite catalyst is used to reduce THF production, closed-loop water recovery system reduces water consumption and carbon emissions. Degradability.

[0024] 4. Intelligent production and function expansion Modular spinneret assembly: supports quick replacement of 6-12 hole special-shaped spinnerets, shortens product switching time, and improves customized order response capabilities.

[0025] Composite functional coating: The surface is coated with a silica-graphene layer to achieve anti-static and self-cleaning functions, meeting the high-frequency signal transmission requirements of electronic substrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the optimization of raw material formula in a high-performance fully drawn polyester fiber and a preparation device thereof according to the present invention; Figure 2 It is a schematic diagram of a high-performance fully drawn polyester fiber and a preparation device in the preparation device of the present invention; Figure 3 The present invention is a schematic diagram of the overall structure of a high-performance fully drawn polyester fiber and a preparation device thereof.

[0027] In the figure: 1. Online viscosity monitoring system; 2. Gradient drafting device; 3. Dynamic mixing screw extrusion system; 4. Screw extruder. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1-Figure 3 : Example 1: Preparation of high-performance polyester fiber based on core technology 1. Raw material preparation Copolyester of terephthalic acid and ethylene glycol: High-quality copolyester chips with an intrinsic viscosity of 0.66dL / g are selected. This intrinsic viscosity has been verified by a large number of experiments in the early stage. In the subsequent melt extrusion and spinning process, it can ensure that the polyester melt exhibits good fluidity and spinnability, thus laying the foundation for the preparation of excellent performance fibers. Its mass fraction is precisely controlled at 98.5%. This ratio can not only ensure the dominant performance of the polyester matrix, but also provide a suitable environment for the effective action of other additives.

[0030] Nano calcium carbonate modifier: Nano calcium carbonate with a particle size of 60nm is used. The nanometer-scale particle size gives it a large specific surface area, which can interact with the polyester matrix more effectively and improve the mechanical properties of the fiber. Its surface is fully treated with a silane coupling agent. The functional group at one end of the silane coupling agent molecule reacts chemically with the hydroxyl group on the surface of the nano calcium carbonate, and the organic functional group at the other end can form good compatibility with the polyester molecular chain, thereby significantly enhancing the dispersibility and compatibility of nano calcium carbonate in the polyester melt. The mass fraction of nano calcium carbonate is set to 1.3%. This ratio will not affect other properties of the fiber due to excessive addition while improving the fiber performance.

[0031] Matting agent titanium dioxide: Anatase titanium dioxide is selected as the matting agent, and its particle size is controlled between 20-30nm. In this particle size range, titanium dioxide can effectively scatter light and achieve an ideal matting effect, but will not have a significant negative impact on the strength and other properties of the fiber due to excessive particle size. The mass fraction is 0.2%, which can ensure that the fiber has a suitable matting effect while maintaining the stability of the overall performance of the fiber. (II) Dynamic mixing screw extrusion system 3 Equipment parameters Screw aspect ratio: Strictly designed in accordance with 40:1, the increase in aspect ratio can significantly increase the residence time of the material in the screw. After simulation calculation and actual production verification, under this aspect ratio, the residence time of the material in the screw can reach 10-15 minutes, ensuring that the material can be fully mixed and the nano calcium carbonate is evenly dispersed in the polyester melt.

[0032] Compression ratio: set to 3.5:1, the material is effectively compressed by gradually reducing the depth of the screw groove from the feeding section to the metering section. In the feeding section, the deeper screw groove can accommodate a large amount of loose material. As the material moves toward the metering section, the screw groove depth gradually decreases, the material is gradually compressed, the density increases, and the mixing effect is significantly improved. For example, the bulk density of the material in the feeding section is about 0.6g / cm³. After compression, the density of the material in the metering section can be increased to about 0.9g / cm³.

[0033] Screw groove depth: Gradually changes from 12mm in the feeding section to 6mm in the metering section. This gradual design is not only conducive to the transportation of materials in the screw, but also can be combined with the change of compression ratio to mix the materials more effectively. In the feeding section, the deeper screw groove allows the materials to quickly enter the screw and be initially mixed. As the screw groove depth gradually decreases, the shear and extrusion effects on the materials gradually increase, promoting the crushing and dispersion of nano calcium carbonate agglomerates.

[0034] Staggered tooth shearing element: There are 3 groups in total, each group contains 6 staggered toothed discs with a tooth depth of 2mm. These staggered toothed discs can exert strong shear force on the material during the rotation of the screw. When the screw rotates at a speed of 300rpm, the linear speed around the toothed disc can reach 5-8m / s. At such a high linear speed, the material is subjected to strong shearing and kneading between the toothed discs, and the nano calcium carbonate agglomerates are quickly broken and evenly dispersed in the polyester melt.

[0035] CFD simulation optimization: Use computational fluid dynamics (CFD) software, such as ANSYS Fluent, to simulate and analyze the screw channel structure. First, establish a three-dimensional model of the screw channel and accurately set the physical properties of the material, including density, viscosity, specific heat capacity, etc., as well as flow parameters such as inlet flow rate and pressure. Through multiple simulation calculations, the position and shape of the shear element are continuously adjusted. For example, in the initial simulation, it was found that there was a dead zone for material flow in some areas. By adjusting the angle of the shear element by 5°-10° and optimizing the curvature radius of the tooth shape, the flow dead zone was successfully eliminated, and the Reynolds number Re>10 in the shear element area was achieved. 4 , forming a strong turbulent field, ensuring that nano-calcium carbonate is efficiently dispersed in the melt.

[0036] (III) Online viscosity monitoring system 1 Hardware composition Ultrasonic sensor: Installed in the melt pipe, its frequency is 5MHz. This frequency has been specially selected and has good adaptability and accuracy in the complex environment of polyester melt. Through experimental comparison of sensors with different frequencies, it is found that the 5MHz sensor has stable signal strength and small interference when collecting melt sound velocity signals, and can accurately reflect the state changes of the melt.

[0037] Controller: Based on the sonic velocity-viscosity model (μ=0.002V²-0.5V+1000, μ is viscosity, V is sonic velocity, and the unit is m / s), the collected sonic velocity signal is processed in real time. This model is obtained by fitting a large amount of experimental data and has high accuracy. In practical applications, the sonic velocity data collected by the sensor is input into the controller in real time, and the controller quickly calculates the viscosity value of the melt through the built-in algorithm, with a calculation accuracy of ±0.5%.

[0038] Control logic: When the melt viscosity fluctuates by more than ±2%, the controller automatically triggers the linkage mechanism. On the one hand, the screw speed is adjusted within a range of ±5%. By changing the screw speed, the residence time of the material in the screw and the degree of shearing effect it receives change, thereby affecting the melt viscosity. For example, when the melt viscosity increases, the screw speed is appropriately reduced to extend the residence time of the material in the screw, which is subjected to more shearing and reduces the viscosity. On the other hand, the melt temperature is adjusted within a range of ±1°C. By utilizing the influence of temperature on the viscosity of polyester melt, when the viscosity increases, the melt temperature is appropriately increased, and vice versa, the temperature is reduced to achieve precise control of the viscosity. In actual production, through this linkage mechanism, the melt viscosity can be stably controlled within the set range to ensure the stability of the spinning process.

[0039] (IV) Gradient drafting device 2 Double hot roller group Temperature gradient: The temperature of the first hot roller is set to 70℃, and the temperature of the second hot roller is set to 125℃, forming a temperature gradient of 65-135℃. In this temperature range, the molecular chains of polyester fibers have appropriate activity. Through molecular dynamics simulation and actual fiber structure analysis, it can be seen that at around 70℃, the fiber molecular chains begin to have a certain degree of activity and can be initially oriented under the action of drafting force; as the temperature rises to 125℃, the activity of the molecular chains is further enhanced, which is conducive to achieving a higher degree of orientation and crystallization during the drafting process, thereby improving the mechanical properties of the fiber.

[0040] Speed ​​ratio: The speed ratio of the double hot rollers is controlled at 1:1.9, that is, the speed of the first hot roller is 2000m / min, and the speed of the second hot roller is 3800m / min. This speed ratio is obtained through a large number of experimental optimizations, which can ensure that the fiber is subjected to appropriate tensile force during the drafting process. Under this speed ratio, the drafting multiple of the fiber between the first hot roller and the second hot roller is about 1.9 times, so that the molecular chain is highly oriented along the fiber axis, while avoiding fiber breakage or internal structural defects caused by excessive drafting force.

[0041] Dynamic tension adjustment component: This component includes a high-precision tension sensor and a servo motor drive system. The tension sensor has an accuracy of up to ±0.1cN and can accurately monitor the tension changes of the fiber during the drawing process in real time. When the tension fluctuation exceeds the set threshold (±3%), the servo motor responds quickly, and the response time can be controlled within 50ms. The tension change is compensated by adjusting the roller speed ratio. For example, when the tension increases, the servo motor quickly reduces the speed of the second hot roller, so that the tension of the fiber during the drawing process returns to the normal range, ensuring that the fiber is drawn under stable tension conditions, reducing the internal stress concentration of the fiber, and improving the fiber quality.

[0042] (V) Spinning and post-processing Spinning process Spinneret: A 12-hole circular spinneret with an aperture of 0.25 mm is used. This aperture design is obtained through spinning experiments comparing spinnerets with different apertures. It can extrude the fully mixed and viscosity-controlled polyester melt at a stable flow rate to form uniform filaments. Under this aperture, the melt extrusion speed is uniform, and the initial diameter deviation of the filaments is extremely small, which is conducive to the consistency of subsequent fiber performance.

[0043] Spinning temperature: set to 280℃, at which the polyester melt has good fluidity and can pass through the spinneret smoothly. Thermogravimetric analysis and rheological tests show that at 280℃, the viscosity of the polyester melt is moderate, which can ensure smooth extrusion of the melt and avoid polyester degradation due to high temperature or insufficient melt fluidity due to low temperature, which affects the spinning quality.

[0044] Side blowing conditions: The side blowing speed is 0.6m / s, the temperature is 22℃, and the humidity is 70%. Appropriate side blowing conditions can make the extruded filaments cool and solidify quickly to form stable nascent fibers. Through numerical simulation and actual observation of the fiber cooling process under different side blowing conditions, it is found that this combination of wind speed, temperature and humidity can ensure uniform fiber cooling, reduce internal structural differences, and make the internal and external structures of the fibers consistent, laying the foundation for subsequent drafting and performance improvement.

[0045] Post-treatment: The fibers after spinning undergo post-treatment processes such as oiling and winding. The oiling agent is a special oil with good lubricity and antistatic properties. After performance testing and actual application comparison of various oiling agents, this special oil can effectively reduce the friction between the fiber and the equipment. The oiling rate is controlled at 0.8%-1.2%. Within this range, the lubrication and antistatic effects of the oiling agent can be fully exerted, and other fiber properties will not be affected by excessive oiling rate. The winding speed is matched with the speed of the second hot roller to ensure that the fiber is tightly and evenly wound. The tension fluctuation of the fiber during the winding process is controlled within a very small range to ensure the stability of the fiber quality. (VI) Performance test Breaking strength: The fiber was tested using an electronic universal material testing machine using the isokinetic stretching method. During the test, the clamping length was 25 mm and the stretching speed was 50 mm / min. The clamping length and stretching speed are determined based on relevant standards and a large number of experiments, and can accurately reflect the breaking strength performance of the fiber. After multiple tests, the breaking strength of the polyester fiber prepared in this embodiment reached 6.3 cN / dtex, meeting the requirement of ≥6.0 cN / dtex, indicating that the fiber has high strength and can meet the needs of a variety of high-strength application scenarios.

[0046] Boiling water shrinkage: The fiber sample is treated in boiling water for 30 minutes, and then its length change is measured to calculate the boiling water shrinkage. This test method is a standard method commonly used in the industry and can effectively evaluate the dimensional stability of the fiber. The boiling water shrinkage of the fiber in this example is 3.0%, which meets the standard of ≤3.5%, indicating that the fiber has good dimensional stability in a high temperature environment and is not prone to excessive shrinkage.

[0047] Diameter CV value: The diameter of 100 fibers was measured using a laser particle size analyzer, and the coefficient of variation (CV value) was calculated. The purpose of measuring 100 fibers is to ensure the statistical significance of the data and to more accurately reflect the uniformity of the fiber diameter. The results show that the diameter CV value of the fiber in this example is 1.0%, which is much better than the industry standard of ≤1.2%, indicating that the fiber diameter uniformity is good and the product quality stability is high.

[0048] Dispersion of nano-calcium carbonate: The distribution of nano-calcium carbonate in the fiber cross section was observed by scanning electron microscopy (SEM), and the dispersion of nano-calcium carbonate was calculated using image analysis software. During the SEM observation process, multiple fiber cross sections were selected for photography, with 5-10 photos taken for each cross section. Then, the nano-calcium carbonate particles in the photos were identified and counted by image analysis software to calculate their dispersion. The results showed that the dispersion of nano-calcium carbonate in the polyester melt reached 98.5%, proving the efficient dispersion effect of the dynamic mixing screw extrusion system 3.

[0049] Example 2: Preparation of polyester fiber by conventional process 1. Raw material formula Copolyester of terephthalic acid and ethylene glycol: Copolyester chips with a common intrinsic viscosity of 0.64 dL / g were selected. This intrinsic viscosity is common in traditional polyester fiber production, but it is slightly inferior to the high-quality chips in Example 1 in terms of melt fluidity and spinnability. The mass fraction is 99.8%. Since no nano-calcium carbonate modifier is added, the performance of the polyester matrix is ​​relatively simple.

[0050] Matting agent titanium dioxide: Ordinary anatase titanium dioxide is used, with a mass fraction of 0.2%. Its particle size distribution is relatively wide, and its matting effect and influence on fiber properties are not as good as the titanium dioxide with precisely screened particle size in Example 1.

[0051] (II) Preparation device Traditional screw extruder 4: The screw length-to-diameter ratio is 30:1. The shorter length-to-diameter ratio results in a shorter residence time of the material in the screw, generally about 5-8 minutes, making it difficult to achieve full mixing of the material. The compression ratio is 2.5:1, and the compression effect is relatively weak, which cannot effectively improve the mixing degree of the material. There is no special shearing element, and the material mixing mainly relies on the conveying effect of the screw, resulting in low mixing efficiency and limited dispersion ability for additives such as nano-calcium carbonate.

[0052] Ordinary spinning equipment: It does not have an online viscosity monitoring system 1 and a gradient drafting device 2. The temperature of the hot roller is constant at 80°C. At this temperature, the mobility of the fiber molecular chain is limited, making it difficult to achieve a high degree of orientation and crystallization. The drafting multiple is 3.0 times, and there is no dynamic tension adjustment function. During the drafting process, the tension cannot be adjusted in real time according to the actual situation of the fiber, which easily leads to uneven stress inside the fiber and affects the fiber quality.

[0053] 3. Spinning process Spinning temperature: set to 275°C. Compared with Example 1, the fluidity of the polyester melt at this temperature is slightly worse, and the melt flow rate may be uneven when passing through the spinneret, affecting the quality of the filaments.

[0054] Side blowing conditions: wind speed 0.5 m / s, temperature 25° C., humidity 65%. Compared with Example 1, the cooling speed and uniformity of the filaments under this side blowing condition are poor, which easily leads to differences in the internal structure of the fiber and affects the performance consistency of the fiber.

[0055] Post-treatment: Similar to Example 1, but the oiling agent is of average quality and the oiling rate is controlled at about 1.0%. The oiling agent of average quality is not as effective as the special oiling agent in Example 1 in reducing the friction between the fiber and the equipment and antistatic performance, and may affect the subsequent processing performance of the fiber.

[0056] (IV) Performance testing Breaking strength: The breaking strength was also tested by isokinetic tensile method, and was only 4.8 cN / dtex, which was significantly lower than that of Example 1. This was mainly because no nano calcium carbonate modifier was added to the raw material formula, and the traditional preparation device and process could not effectively improve the strength of the fiber.

[0057] Boiling water shrinkage: After testing, the boiling water shrinkage was 6.5%, which is much higher than that of Example 1. This is because the crystallization and orientation of the fiber under the traditional process are not ideal, and the stability of the fiber molecular chain is poor in a high temperature environment, which is prone to shrinkage.

[0058] Diameter CV value: The results of the laser particle size analyzer showed that the diameter CV value was 2.5%, and the fiber diameter uniformity was poor. This was because the traditional screw extruder 4 had a poor mixing effect, resulting in uneven distribution of the components in the melt, which in turn affected the consistency of the fiber diameter.

[0059] Dispersion of nano-calcium carbonate: Since no nano-calcium carbonate is added, there is no dispersion problem. However, it can be indirectly seen from the fiber performance that the fibers prepared by traditional processes have deficiencies in mechanical properties and other aspects and cannot meet the needs of high-end applications.

[0060] Example 3: Process with lack of dynamic mixing of the screw 1. Raw material formula Similar to Example 1, the purpose is to compare the effect of the lack of dynamic mixing of the screw on fiber preparation under the same raw material formula.

[0061] (II) Preparation device Screw extruder 4: The screw length-diameter ratio is 40:1, and the compression ratio is 3.5:1, but no staggered tooth shearing element is set, and only the conveying and simple mixing function of the ordinary screw is relied on. In this case, the mixing of materials in the screw mainly depends on molecular diffusion and laminar mixing, and the mixing efficiency is much lower than that of the device with dynamic mixing of the screw.

[0062] Equipped with an online viscosity monitoring system 1 and a gradient drafting device 2: the same as in the first embodiment, to highlight the key role of dynamic mixing of the screw in the entire preparation process and eliminate interference from other factors.

[0063] 3. Spinning process As in Example 1, the comparison was performed under the same spinning process conditions.

[0064] (IV) Performance testing Breaking strength: The test result is 5.5 cN / dtex, which is lower than that of Example 1. This indicates that the screw lacks the efficient dispersion effect of dynamic mixing on nano-calcium carbonate, and the nano-calcium carbonate is unevenly dispersed in the melt, and cannot fully play its role in enhancing the mechanical properties of the fiber, resulting in the mechanical properties of the fiber being affected.

[0065] Boiling water shrinkage: 4.0%, higher than Example 1. Due to the uneven dispersion of nano calcium carbonate, the crystallization and orientation of the fiber are not as ideal as in Example 1, and the dimensional stability of the fiber decreases at high temperatures.

[0066] Diameter CV value: 1.5%, the uniformity of fiber diameter has decreased. The uneven dispersion of nano calcium carbonate makes the extrusion of each part of the melt different when passing through the spinneret, resulting in poor consistency of fiber diameter.

[0067] Dispersion of nano-calcium carbonate: Through SEM observation and image analysis, the dispersion of nano-calcium carbonate is only 85%, which is much lower than 98.5% in Example 1. This directly proves the key role of dynamic mixing of the screw in the dispersion of nano-calcium carbonate, and its unique structure and shearing elements can effectively promote the breakage and uniformity of nano-calcium carbonate agglomerates.

[0068] Example 4: Process without using online viscosity monitoring system 1 1. Raw material formula The same as the first embodiment, thereby ensuring that on the basis of the same raw materials, the influence of the online viscosity monitoring system 1 on the fiber preparation process and performance is highlighted.

[0069] (II) Preparation device Dynamic mixing screw extrusion system 3: completely consistent with Example 1, ensuring that the role of the screw in the material mixing and dispersion link is not affected, so as to accurately compare the difference caused by the lack of online viscosity monitoring system 1. Spinning equipment: equipped with gradient drafting device 2, but not equipped with online viscosity monitoring system 1. This means that in the spinning process, it is impossible to obtain melt viscosity data in real time and adjust process parameters accordingly, and the fluctuation of melt viscosity cannot be timely and effectively controlled.

[0070] (III) Spinning process Consistent with Example 1, the spinning operation was performed under the conditions of spinning temperature set to 280°C, side blowing speed of 0.6 m / s, temperature of 22°C, humidity of 70%, etc., so as to analyze the result changes caused by the lack of online viscosity monitoring system 1 under the same spinning environment.

[0071] (IV) Performance testing Breaking strength: The test value is 5.8 cN / dtex, which is lower than that of Example 1. Fluctuations in melt viscosity can affect the uniformity of the internal structure of the fiber and the orientation of the molecular chains. During the spinning process, when the melt viscosity is unstable, the stress on the fiber during the stretching process is uneven, resulting in an increase in internal defects in the fiber, thereby reducing the breaking strength of the fiber.

[0072] Boiling water shrinkage: 3.8%, higher than that of Example 1. Since the melt viscosity fluctuation cannot be adjusted in time, the crystallization and orientation of the fiber are disturbed during the molding process, which reduces the stability of the fiber molecular chain in a high temperature environment and makes it more likely to shrink, which in turn leads to an increase in boiling water shrinkage.

[0073] Diameter CV value: 1.3%, the fiber diameter uniformity is slightly inferior to that of Example 1. The instability of melt viscosity will cause the melt to flow unevenly when extruded from the spinneret, resulting in a large deviation in the fiber diameter, affecting the consistency of the fiber diameter.

[0074] Spinning breakage rate: During the spinning process, due to the fluctuation of melt viscosity, the breakage rate reached 1.5 times / 1000 spindle hours, which was much higher than 0.5 times / 1000 spindle hours in Example 1. Too high or too low melt viscosity will cause uneven tension on the fiber during the spinning process, thus causing fiber breakage and seriously affecting production efficiency.

[0075] Embodiment 5: Process without gradient drafting device 2 1. Raw material formula Similar to the first embodiment, the consistency of the raw materials was maintained, and the influence of the gradient drafting device 2 on the fiber properties was examined in detail.

[0076] (II) Preparation device Dynamic mixing screw extrusion system 3: Same as the first embodiment, ensuring the same processing of materials in the early mixing and dispersion stages.

[0077] Online viscosity monitoring system 1: Same as in Example 1, ensuring stable control of melt viscosity.

[0078] Spinning equipment: It uses an ordinary single hot roller drawing device, the temperature of the hot roller is constant at 90°C, and it does not have the function of temperature gradient and dynamic tension adjustment. This device cannot provide appropriate temperature and tension conditions according to the different stages of the fiber drawing process.

[0079] 3. Spinning process The spinning temperature, side blowing conditions and post-treatment are consistent with those of the first embodiment, and there is only a difference in the drafting process, so as to clarify the importance of the gradient drafting device 2 in the entire spinning process.

[0080] (IV) Performance testing Breaking strength: The test result is 5.2 cN / dtex, which is lower than that of Example 1. Due to the lack of gradient temperature field and dynamic tension adjustment, the fiber molecular chains cannot be fully oriented and crystallized during the drawing process, resulting in an insufficiently tight internal structure of the fiber and reduced strength.

[0081] Boiling water shrinkage: 4.5%, significantly higher than Example 1. The common single hot roller drafting device cannot make the fiber molecular chain form a good orientation and crystal structure. In a high temperature environment, the fiber molecular chain is prone to relaxation and shrinkage, resulting in an increase in boiling water shrinkage.

[0082] Diameter CV value: 1.6%, fiber diameter uniformity is poor. During the drafting process, due to the lack of dynamic tension adjustment, the tension on the fiber is uneven, resulting in inconsistent stretching degrees at different locations of the fiber, which leads to increased fiber diameter differences.

[0083] Summarize Through the detailed comparison between Example 1 and Comparative Examples 2, 3, 4, and 5, it can be clearly seen that the high-performance fully drawn polyester fiber and its preparation device of the present invention have innovative advantages in terms of raw material formula, preparation device, and process conditions. Example 1 uses a unique raw material formula, especially the reasonable addition of nano-calcium carbonate modifier, combined with the efficient dispersion of nano-calcium carbonate by the dynamic mixing screw extrusion system 3, the precise regulation of process stability by the online viscosity monitoring system 1, and the optimization of the fiber structure by the gradient drawing device 2. The prepared polyester fiber is significantly superior to the conventional process and the comparative examples lacking key innovative technologies in terms of performance indicators such as breaking strength, boiling water shrinkage, and diameter CV value.

[0084] From an economic point of view, although the initial cost of the invention in terms of equipment investment and process optimization has increased, from a long-term production benefit analysis, due to the improvement of production efficiency, product quality and reduction of scrap rate, the overall cost per unit product can be significantly reduced. Taking a chemical fiber production enterprise as an example, if the technology of the invention is adopted, it is expected to increase economic benefits by about 10 million yuan per year.

[0085] In terms of environmental benefits, the present invention reduces energy consumption by optimizing the process. At the same time, due to the improvement of product performance and the extension of product life, it indirectly reduces resource waste and waste emissions. It is estimated that compared with traditional processes, carbon emissions can be reduced by about 0.5 tons for every ton of fiber produced.

[0086] The technical solution of the present invention has significant creativity, novelty and practicality, can effectively improve the performance of polyester fibers, meet the high-end market demand for high-performance fiber materials, and has broad application prospects and industrial value. In the future, with the continuous development and improvement of technology, it is expected to further expand its application in aerospace, high-end medical and other fields with extremely stringent requirements on fiber performance, providing strong technical support for the development of related industries.

Claims

1. A high-performance fully drawn polyester fiber, characterized in that: The fibers are made from the following raw materials in mass fractions: Terephthalic acid and ethylene glycol copolymer polyester: 98.2%-98.8%; Nano calcium carbonate modifier: 1.2%-1.8%; Matting agent titanium dioxide: 0.15%-0.2%; The breaking strength of the fiber is ≥6.0cN / dtex, the boiling water shrinkage is ≤3.5%, and the diameter CV value is ≤1.2%.

2. A high performance fully drawn polyester fiber as claimed in claim 1, characterized in that: The surface of nano calcium carbonate is treated with silane coupling agent, the particle size is 50-80nm, and the dispersion degree in polyester melt is ≥98%.

3. A high performance fully drawn polyester fiber as claimed in claim 1, characterized in that: The fibers also contain 5% to 15% by weight of a bio-based copolymer for degradation.

4. The high performance fully drawn polyester fiber according to claim 1, characterized in that: The fiber surface is coated with a silica-graphene composite layer with a surface resistivity of ≤10 9 Ω, used for anti-static.

5. The high performance fully drawn polyester fiber according to claim 1, characterized in that: The fiber has a core-shell structure, with the core layer being high-strength polyester and the skin layer being polylactic acid, and is used to absorb medical materials.

6. A device for preparing high-performance fully drawn polyester fibers, characterized in that: For preparing the high-performance fully drawn polyester fiber according to any one of claims 1 to 5, the preparation device comprises: Dynamic mixing screw extruder system (3): The screw length-to-diameter ratio is 40:1, the compression ratio is 3.5:1, the screw groove depth gradually changes from 12 mm in the feed section to 6 mm in the metering section, and it is equipped with 3 sets of staggered tooth shear elements; Online viscosity monitoring system (1): including ultrasonic sensors in the melt pipe and linked screw speed / temperature control modules; Gradient drawing device (2): includes a double hot roller group with a temperature gradient of 65-135°C and a dynamic tension adjustment component.

7. The device for preparing high-performance fully drawn polyester fiber according to claim 6, characterized in that: The screw channel structure is optimized through CFD simulation, and the Reynolds number in the shear element area is Re>10 4 .

8. The device for preparing high-performance fully drawn polyester fiber according to claim 6, characterized in that: The online viscosity monitoring system (1) uses the sonic velocity-viscosity model to control the melt viscosity in real time, with a fluctuation range of ≤±2%.

9. The device for preparing high-performance fully drawn polyester fiber according to claim 6, characterized in that: The speed ratio of the dual hot rollers of the gradient drawing device (2) is 1:1.8-1:2.0, and the temperature of the second hot roller is 115-135°C.

10. A device for preparing high-performance fully drawn polyester fibers according to any one of claims 7 to 9, characterized in that: Also includes: Infrared radiation heating zone, set in the spinning tunnel, with a temperature of 120-150°C, is used to induce pre-crystallization; Modular spinneret assembly supports quick replacement of 6-12 hole special-shaped spinnerets.

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