Demonomerisation device and demonomerisation method of carbon fiber polymerization liquid and preparation method of spinning liquid

Abstract

The invention relates to a demonomerisation device and a demonomerisation method of a carbon fiber polymerization solution and a preparation method of a spinning solution, and belongs to the field of fiber materials. The method solves at least one of the problems that the existing demonomerisation equipment and process are low in demonomerisation efficiency, the equipment is easy to crust or coke, the operation is unstable, the requirements on processing precision or process parameters are very harsh and the like when being used for treating the high-molecular-weight carbon fiber spinning solution. A demonomerisation device for carbon fiber polymerization liquid comprises a tank body and multiple layers of perforated partition plates arranged in the tank body, the multiple layers of perforated partition plates are arranged in a layered mode from top to bottom in the axial direction of the tank body, each layer of perforated partition plate is perpendicular to the axial direction of the tank body, and each layer of perforated partition plate comprises a fixed end on one side and a suspended end on the other side. The suspended ends of the multiple layers of partition plates with the holes are arranged alternately in a staggered mode in space. The demonomerisation efficiency and effect are improved, the inner wall of the demonomerisation device is prevented from skinning or coking, and formation of gel in a polymerization solution is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the field of fiber materials, and particularly to a device for removing monomers from a carbon fiber polymerization solution, a method for removing monomers, and a method for preparing a spinning solution. Background Art

[0002] High-molecular-weight polyacrylonitrile spinning solution is of great significance for carbon fibers, as it can significantly improve the properties of carbon fibers, such as strength, modulus, and heat resistance. However, in the polymerization solution after polymerization, residual monomers and low-molecular-weight polymers will affect the fiber properties, and acrylonitrile itself is highly toxic. If not removed, it will have a serious impact on the spinning process and the operating environment.

[0003] The existing high-molecular-weight polymerization solution faces challenges in the preparation process, especially in the monomer removal step. In the monomer removal process, common equipment includes packed towers, falling film towers, high-gravity rotating beds, static umbrella leaves or dynamic scraper equipment, and screw-type devolatilization extrusion devices. These devices have their own advantages and disadvantages, but when dealing with high-molecular-weight polymerization solutions, there are generally some problems. For example, packed towers are prone to blockage and dead corners, falling film towers have difficulty forming liquid films when dealing with high-viscosity materials, high-gravity rotating beds may have uneven material distribution and coking in high-molecular-weight polymerization solutions, static umbrella leaves or dynamic scraper equipment have low interface renewal efficiency in high-viscosity systems, and screw-type devolatilization extrusion devices are difficult to fully remove monomers due to short residence times. The problem of monomer removal from high-molecular-weight polyacrylonitrile polymerization solution has become increasingly prominent due to the limitations of existing monomer removal equipment and unreasonable process parameters, becoming one of the key bottlenecks restricting carbon fiber production. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a device for removing monomers from a carbon fiber polymerization solution, a method for removing monomers, and a method for preparing a spinning solution, so as to solve at least one of the problems of low monomer removal efficiency, easy skinning or coking of equipment, unstable operation, and very strict requirements for processing accuracy or process parameters existing in the existing monomer removal equipment and processes when dealing with high-molecular-weight carbon fiber spinning solutions.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] The present invention provides a device for removing monomers from a carbon fiber polymerization solution. The monomer removal device includes a tank body and multiple layers of perforated partitions arranged in the tank body from top to bottom along the axial direction of the tank body. Each layer of perforated partition is perpendicular to the axial direction of the tank body. Each layer of perforated partition includes a fixed end on one side and a suspended end on the other side. The fixed end is conformally fixed to the inner wall of the tank body, and the suspended end on the other side extends freely. The suspended end of one layer of perforated partition is located on one side of the axial direction of the tank body, and the suspended ends of adjacent layers of perforated partitions are located on the other side of the axial direction of the tank body. The suspended ends of multiple layers of perforated partitions form an alternating staggered layout in space.

[0007] Further, the area of the perforated partition on each layer accounts for 80%-90% of the cross-sectional area of the tank body at the position of this layer, and the remaining 10%-20% serves as a smooth channel for the flow of the polymerization liquid.

[0008] Further, the holes of the perforated partitions on adjacent layers are arranged in a staggered layer pattern, and the hole positions on the perforated partition of each layer are offset relative to the hole positions on the perforated partition of its directly adjacent layer.

[0009] Further, inside the tank body, the distance between the first perforated partition and the last perforated partition accounts for a ratio of 1 / 2 to 4 / 5 of the total height of the tank body.

[0010] Further, a polymerization liquid inlet is provided at the top or upper part of the tank body. A perforated distribution plate is provided between the polymerization liquid inlet and the adjacent first perforated partition, and the distribution plate is arranged parallel to the first perforated partition.

[0011] Further, the area ratio of the distribution plate to the first perforated partition is 40%-60%; and / or,

[0012] The ratio of the distance between the upper surface of the distribution plate and the lower end of the polymerization liquid inlet to the distance between the lower end of the polymerization liquid inlet and the upper surface of the first perforated partition is 15%-40%.

[0013] The present invention provides a method for removing monomers from a carbon fiber polymerization liquid, and the above monomer removal device is used to remove monomers from the carbon fiber polymerization liquid.

[0014] Further, the inlet liquid flow rate Q of the carbon fiber polymerization liquid entering the monomer removal device 1 and the inlet gas flow rate Q of the solvent vapor entering the monomer removal device 2 satisfy:

[0015] Q 2 ≥k×Q 1 ×m×α×1000

[0016] wherein, the unit of Q 1 is m 3 / h, the unit of Q 2 is L / h, m is the mass percentage of the residual monomers in the carbon fiber polymerization liquid; α is the flow coefficient of the solvent vapor, and the value range of α is 1.0-1.2; k is the proportionality coefficient, and the value range of k is 1.5-1.9.

[0017] Further, the inlet liquid temperature of the carbon fiber polymerization liquid is 50-70°C; and / or,

[0018] the inlet gas temperature of the solvent vapor is 80-100°C; and / or,

[0019] The inlet viscosity of the carbon fiber polymerization liquid is 600 - 1000P; and / or,

[0020] The inlet pressure of the solvent vapor is 0.01 - 0.5 Mpa.

[0021] The present invention provides a method for preparing a carbon fiber spinning solution, comprising:

[0022] Preparing an acrylonitrile-based polymerization liquid;

[0023] Performing subsequent treatment on the acrylonitrile-based polymerization liquid to obtain a carbon fiber spinning solution; the subsequent treatment includes degassing treatment; the degassing treatment includes degassing the acrylonitrile-based polymerization liquid using the above degassing device or the above degassing method.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0025] (1) The present invention provides a multi-layered perforated partition in the degassing device. The polymerization liquid forms a thin liquid layer on each layer of the partition, and the suspended ends of adjacent partitions are staggered to ensure smooth flow of the polymerization liquid. This structural design optimizes the flow path of the polymerization liquid in the tank. On the one hand, the specific surface area of the material is increased through the thin liquid layer, and on the other hand, the residence time of the liquid in the device is extended, providing more opportunities for the solvent vapor to contact the residual monomers, thereby significantly improving the degassing effect.

[0026] (2) The degassing device of the present invention designs a channel between the suspended end of each layer of the perforated partition and the inner wall of the tank to ensure that the polymerization liquid can flow smoothly to the next layer after forming a thin liquid layer. This structure not only realizes the uniform distribution and effective guidance of the high molecular weight and high viscosity polymerization liquid material on the partition, but also significantly reduces problems such as coking, crusting, or gel formation in the polymerization liquid that are prone to occur in traditional devices. In addition, it effectively avoids blockage inside the degassing device, improves operation stability, reduces equipment cleaning and maintenance costs, and improves production efficiency.

[0027] (3) Different from the existing process, the degassing method of the present invention uses a novel degassing device to treat the polymerization liquid. After the polymerization liquid is introduced into the degassing device, it is evenly distributed on the first layer of the perforated partition through the porous distribution to form a uniform thin liquid layer; the polymerization liquid mainly flows through the holes on the partition to the next layer of the partition and continues to form a thin liquid layer on the lower layer of the partition, thereby ensuring that the thin liquid layer of the polymerization liquid on each layer of the partition can perform efficient gas-liquid exchange with the solvent vapor. At the same time, the excess high viscosity material can flow smoothly to the next layer of the partition through the channel between the suspended end of the partition and the inner wall of the tank; this flow path not only ensures the degassing effect, but also effectively avoids equipment crusting or coking, reduces gel formation in the polymerization liquid, and ensures the efficient progress of production.

[0028] (4) The single - monomer removal method of the present invention optimizes the distribution and flow path of the polymerized liquid material through the innovative structural design of the single - monomer removal device, significantly improving the single - monomer removal effect and efficiency. Compared with traditional single - monomer removal methods such as falling - film towers and high - gravity rotating beds, the present invention greatly reduces the stringent requirements for process parameters and equipment processing precision. Especially when treating acrylonitrile - based polymerized liquids with higher viscosity and high molecular weight, the present invention shows better adaptability and stability, effectively avoiding common problems such as coking and scaling in traditional methods, and significantly reducing the formation of gels in the polymerized liquid.

[0029] (5) In some preferred embodiments, better single - monomer removal effects can be obtained by optimizing the structural parameters of multi - layer perforated partitions, distribution plates, etc. inside the single - monomer removal device. Using the single - monomer removal device and method provided by the present invention to perform single - monomer removal treatment on carbon fiber polymerized liquid can ensure that the content of residual monomers in the polymerized liquid after single - monomer removal is reduced to less than 100 ppm.

[0030] (6) In some preferred embodiments, by precisely controlling the process parameters of single - monomer removal, such as the inlet flow rate of the polymerized liquid, the inlet flow rate of solvent vapor, the inlet temperature of the polymerized liquid, the inlet temperature / pressure of solvent vapor, etc., it is beneficial to improve the single - monomer removal efficiency and effect, avoid equipment scaling or coking, and significantly reduce the formation of gels in the polymerized liquid. In some embodiments, the single - monomer removal effect is significant, the residual monomer content after single - monomer removal is less than 100 ppm, and the single - monomer removal process is efficient and continuous. The polymerized liquid can continuously enter and flow out of the single - monomer removal device according to the working conditions. In addition, the phenomenon of equipment scaling or coking is greatly reduced. Through the viewing window on the single - monomer removal device, there is no obvious discoloration on the inner wall of the device. In traditional single - monomer removal devices, due to uneven heat reception during the flow of the polymerized liquid, local gels are generated, and even coking occurs on the inner wall of the device, resulting in the filter replacement cycle for removing gels from the polymerized liquid after single - monomer removal being only 1 - 2 months, or even shorter. However, with the single - monomer removal treatment of the present invention, the formation of gels in the polymerized liquid is significantly reduced, and the filter replacement cycle is extended to more than 3 months, improving the operation efficiency and service life of the equipment. The above - mentioned replacement cycle is based on the condition that the pressure increase reaches half of the filter's pressure - resistant rating as the filter replacement condition.

[0031] In the present invention, the above - mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can be made obvious from the description, or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained from the content specifically pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings are only used for the purpose of showing specific embodiments and are not considered as a limitation to the present invention. Throughout the drawings, the same reference signs represent the same components.

[0033] Figure 1 Structural schematic diagram of the degassing device provided by an embodiment of the present invention;

[0034] Figure 2 Structural schematic diagram of the ammoniation device provided by an embodiment of the present invention;

[0035] Figure 3 Structural schematic diagram of the polymerization device provided by an embodiment of the present invention;

[0036] Reference numerals:

[0037] 100 - Degassing device; A - Tank body; B - Solvent vaporizer; C - Real-time viscosity monitoring device; 11 - Perforated partition; 12 - Polymerization liquid inlet; 13 - Distribution plate; 14 - Solvent inlet; 15 - Coiled pipe; 15a - Coiled pipe inlet; 15b - Coiled pipe outlet; 16 - Solvent vapor; 17 - Vacuum extraction port; 18 - Polymerization liquid outlet; 200 - Ammoniation device; 21 - Inclined paddle stirrer; 21a - Stirring paddle; 21b - Rotating shaft; 22 - Ammonia gas inlet; 23 - Polymerization liquid inlet; 24 - Polymerization liquid outlet; 25 - First motor; 300 - Polymerization device; 31 - Stirring device; 32 - Inert gas inlet; 33 - Inert gas outlet; 34 - Second motor; 35 - Online pressure-viscosity converter; 36 - Constant-speed gear pump; 37 - Circulating water inlet; 38 - Circulating water outlet. Detailed implementation manners

[0038] The following will specifically describe the preferred embodiments of the present invention with reference to the accompanying drawings. The accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0039] In the first aspect, the present invention provides a degassing device for a carbon fiber polymerization liquid. The degassing device 100 includes a tank body and multiple layers of perforated partitions 11 arranged in the tank body. The multiple layers of perforated partitions are arranged in layers from top to bottom along the axial direction of the tank body, and each layer of perforated partition is perpendicular to the axial direction of the tank body. Each layer of perforated partition includes a fixed end on one side and a suspended end on the other side. The fixed end is conformally fixed to the inner wall of the tank body, and the other suspended end extends freely. The suspended end of the upper layer of perforated partition is located on one side of the axial direction of the tank body, and the suspended end of the lower layer of perforated partition adjacent to the upper layer of perforated partition is located on the other side of the axial direction of the tank body. The suspended ends of the multiple layers of perforated partitions form an alternating staggered layout in space.

[0040] Preferably, the area of each layer of perforated partition accounts for 80% - 90% of the cross-sectional area of the tank body at the position of this layer, and the remaining 10 - 20% serves as a smooth channel for the polymerization liquid to flow.

[0041] Preferably, the holes of adjacent perforated partitions are arranged in a staggered layer distribution, and the hole positions on each perforated partition are offset relative to the hole positions of the directly adjacent perforated partition in the adjacent layer. This setting of the staggered layer distribution of holes can further increase the contact area and time between the solvent vapor and the polymerization liquid, thereby improving the gas-liquid exchange efficiency, helping the solvent vapor to more effectively remove the residual monomers in the polymerization liquid. In addition, the holes with staggered layer distribution can optimize the flow path, make the polymerization liquid flow more uniformly, reduce the local overheating or overcooling conditions, reduce the risk of coking and scaling, and reduce the formation of gels in the polymerization liquid.

[0042] Preferably, multiple perforated partitions are arranged in parallel and equidistantly from top to bottom along the axial direction of the tank body. By adopting the above preferred partition distribution method, it helps to achieve the uniform flow of the polymerization liquid in the tank body, reduce the flow dead zone, reduce the risk of coking and scaling, reduce the formation of gels in the polymerization liquid, ensure that the solvent vapor is fully in contact with the polymerization liquid, and improve the monomer removal effect and efficiency.

[0043] Preferably, in the tank body, the ratio of the distance between the first perforated partition and the last perforated partition to the total height of the tank body is 1 / 2 to 4 / 5, preferably 60%-70%, such as 2 / 3. This can make more full use of the tank body space, increase the contact time and area between the polymerization liquid and the solvent vapor, improve the monomer removal effect and efficiency. By leaving appropriate space above and below, it helps the heat transfer and mass transfer processes to proceed, ensures the uniform distribution of heat and substances throughout the tank body, reduces the dead zone of the polymerization liquid in the tank body, avoids local overheating or overcooling, and is beneficial to reducing the risk of coking and scaling and reducing the formation of gels in the polymerization liquid.

[0044] Furthermore, a polymerization liquid inlet 12 is provided at the top or upper part of the tank body. A perforated distribution plate 13 is provided between the polymerization liquid inlet 12 and the adjacent first perforated partition, and the distribution plate 13 is arranged in parallel with the first perforated partition.

[0045] Preferably, the area ratio of the distribution plate 13 to the first perforated partition is 40%-60%, more preferably 45%-55%.

[0046] Preferably, the ratio of the distance between the upper surface of the distribution plate 13 and the lower end of the polymerization liquid inlet 12 to the distance between the lower end of the polymerization liquid inlet 12 and the upper surface of the first perforated partition is 15%-40%; more preferably 20%-30%.

[0047] The main function of the distribution plate is to distribute the polymer solution entering from the feed port evenly to the first layer of perforated partitions after being distributed through the porous distribution, so that a relatively uniform thin polymer solution layer is formed on the perforated partitions. By controlling the spatial layout of the distribution plate in the tank body and the area ratio to the adjacent perforated partitions, it is conducive to forming a more uniform thin polymer solution layer, increasing the contact area and time between the polymer solution and the solvent vapor, and improving the removal effect and efficiency.

[0048] By precisely controlling the shape and structural parameters of the perforated baffles and their spatial layout in the tank, it is beneficial to improve the single-piece removal effect, avoid local overheating or overcooling, further reduce the risk of coking and skinning, and reduce the formation of gel in the polymerization liquid. Specifically, the perforated baffles have at least one of the following characteristics:

[0049] (a) the number of layers of the perforated partition is 4-8;

[0050] (b) The hole size on each layer of perforated partition is 0.5-2 mm, and the hole spacing is 10-40 mm; illustratively, the hole size is 1 mm, 1.5 mm; the hole spacing is 20 mm, 30 mm.

[0051] (c) The arrangement of the multiple holes on each layer of the perforated partition is preferably a circular array; further, the multiple holes cover the entire perforated partition.

[0052] (d) The spacing between two adjacent layers of perforated partitions is 300-800 mm; preferably 400-600 mm, for example 500 mm;

[0053] (e) The thickness of each layer of perforated partition is 6-12 mm;

[0054] (f) The holes of adjacent perforated partitions are arranged in staggered layers, and the offset distance between the centers of the corresponding holes in adjacent layers is 10-30 mm; preferably, they are arranged in an alternating staggered manner: the odd-numbered layers and the even-numbered layers are kept consistent, but the odd-numbered layers are staggered a certain distance from the even-numbered layers.

[0055] (g) In order to make the polymer solution spread into a thin film on the perforated partition plate to improve the single removal effect, preferably, the material of the perforated partition plate is selected from 316L stainless steel, 1Cr18NiMo3 stainless steel, and AL-1100 aluminum alloy. The above materials are all commercially available alloy grades.

[0056] Further, a solvent vapor inlet is provided at the lower part of the tank body. The monomer removal device further includes a solvent vaporizer B. The upper part of the solvent vaporizer B is communicated with the solvent vapor inlet through a pipeline. A solvent inlet 14 is provided at the bottom of the solvent vaporizer B. A coil 15 is arranged inside the solvent vaporizer B. One end of the coil 15 is communicated with a coil inlet 15a arranged at the upper part of the solvent vaporizer B, and the other end of the coil 15 is communicated with a coil outlet 15b arranged at the lower part of the solvent vaporizer B.

[0057] It can be understood that during operation, the solvent enters the solvent vaporizer B from the solvent inlet 14, the water vapor enters the coil from the coil inlet 15a, flows along the coil, and finally flows out from the coil outlet 15b. During the process of the water vapor flowing in the coil, heat is transferred to the solvent outside the coil, vaporizing it into solvent vapor 16, and the solvent vapor 16 flows into the tank body A through the solvent vapor inlet.

[0058] Exemplarily, the solvent vapor inlet is arranged below the last layer of perforated partition plates and above the liquid level of the monomer-removed polymerized liquid and the liquefied solvent mixture collected at the bottom of the tank body A.

[0059] Specifically, a vacuum extraction port 17 is provided at the upper part or the top of the tank body A; the monomer removal device further includes a liquid ring vacuum jet device, which is connected to the vacuum extraction port 17 through a pipeline, so as to provide a stable negative pressure inside the tank body A of the monomer removal device and discharge the solvent vapor carrying monomers. Specifically, a heating jacket is arranged on the outer wall of the tank body A to make the polymerized liquid inside the tank body A reach the required monomer removal temperature.

[0060] Specifically, a polymerized liquid discharge port 18 is provided at the lower part or the bottom of the tank body A.

[0061] In a second aspect, the present invention provides a method for removing monomers from a carbon fiber polymerized liquid, using the monomer removal device as described in the first aspect to remove monomers from the carbon fiber polymerized liquid.

[0062] Specifically, in the monomer removal method, the polymerized liquid performs gas-liquid exchange with the solvent vapor flowing countercurrently through multiple layers of perforated partition plates. At each layer of perforated partition plate, the polymerized liquid is divided into two parts: one part of the polymerized liquid spreads out on the perforated partition plate to form a thin liquid layer and flows downward through the holes on the perforated partition plate, and the other part of the polymerized liquid flows downward from the suspended end on the side of the perforated partition plate.

[0063] The single-removal method of the present invention relies on the unique structure of the single-removal device. During the single-removal process, by optimizing the flow path of the polymerization solution, it can not only ensure that the polymerization solution spreads out to form a large-area thin liquid layer, having sufficient contact area and sufficient contact time with the solvent vapor, thereby obtaining a good single-removal effect, but also, the present invention can, when dealing with high-molecular-weight and high-viscosity polymerization solutions with greater single-removal difficulty, enable the polymerization solution to flow smoothly to the next layer through the channels reserved at the suspended ends of each layer of partition plates, thereby avoiding problems such as crusting, coking on the inner wall of the device, or reducing the formation of gels in the polymerization solution, which are prone to occur in traditional single-removal processes. Through further optimization of the flow path of the polymerization solution, the upper-layer polymerization solution flows onto the lower-layer partition plate and then continues to spread and flow, enabling the polymerization solution to have more opportunities for gas-liquid exchange with the solvent vapor and improving the single-removal effect.

[0064] Preferably, a part of the polymerization solution flows through the holes on the perforated partition plate to the next-layer perforated partition plate or the polymerization solution collection area, and the positions of the holes where the polymerization solution flows out of the perforated partition plates of adjacent layers are different. The other part of the polymerization solution flows from the suspended end on the side of the perforated partition plate to the next-layer perforated partition plate or the polymerization solution collection area. During the single-removal process, relying on the staggered distribution of the holes on the multi-layer partition plates in the single-removal device of the present invention, the flow path of the polymerization solution is further optimized, prolonging the contact area and time between the polymerization solution and the solvent vapor, ensuring that unreacted monomers (such as acrylonitrile) are more fully removed, and meeting the single-removal requirements of carbon fiber polymerization solutions, especially high-molecular-weight polymerization solutions.

[0065] In some embodiments, during the single-removal process, the polymerization solution enters the single-removal device from the top or upper part of the single-removal device. After multi-hole distribution, it is distributed onto the first-layer perforated partition plate, enabling the polymerization solution to be more evenly distributed on the first-layer perforated partition plate and improving the single-removal effect and efficiency. The multi-hole distribution is realized by the distribution plate 13 in the single-removal device.

[0066] It can be understood that the steps of the single-removal method include: the polymerization solution enters the single-removal device, after multi-hole distribution, flows through the multi-layer perforated partition plates from top to bottom in sequence, forming a continuous liquid film flow; at the same time, the solvent vapor enters the single-removal device, passes through the multi-layer perforated partition plates from bottom to top in sequence, fully contacts the flowing-down polymerization solution and conducts gas-liquid exchange, and the solvent vapor carries the residual volatile monomers in the polymerization solution and is discharged from the single-removal device; the polymerization solution after single-removal treatment is discharged from the single-removal device to complete the single-removal process.

[0067] Exemplarily, the single-removal is carried out under negative pressure. The vacuum degree of the negative pressure is 100 - 5000 Pa. Exemplarily, the vacuum degrees are 200 Pa, 500 Pa, 800 Pa, 1000 Pa, 2000 Pa, 3000 Pa, 4000 Pa. Preferably, the vacuum degree is 500 - 2000 Pa.

[0068] Preferably, during the debatching process, the inlet temperature of the carbon fiber polymerization liquid is 50 - 70°C, preferably 65 - 70°C. Exemplarily, the inlet temperature of the polymerization liquid is 54°C, 58°C, 62°C, 66°C.

[0069] Preferably, during the debatching process, the inlet flow rate of the carbon fiber polymerization liquid is 3 - 5 m 3 / h, preferably 3 - 4 m 3 / h. During the debatching process, the temperature of the debatching system is controlled at 50 - 70°C. More preferably, the temperature of the debatching system gradually increases from top to bottom. Exemplarily, the inlet flow rate of the polymerization liquid is 3.3 m 3 / h, 3.6 m 3 / h, 3.9 m 3 / h, 4.2 m 3 / h, 4.5 m 3 / h, 4.8 m 3 / h.

[0070] Preferably, during the debatching process, the inlet temperature of the solvent vapor is 80 - 100°C; more preferably 90 - 100°C. Exemplarily, the inlet temperature of the solvent vapor is 84°C, 88°C, 92°C, 96°C.

[0071] Preferably, during the debatching process, the inlet pressure of the solvent vapor is 0.01 - 0.5 Mpa; more preferably 0.2 - 0.3 Mpa. Exemplarily, the inlet pressure of the solvent vapor is 0.05 Mpa, 0.1 Mpa, 0.15 Mpa, 0.25 Mpa, 0.35 Mpa, 0.40 Mpa, 0.45 Mpa.

[0072] In some embodiments, during debatching, the inlet viscosity of the carbon fiber polymerization liquid is 600 - 1000 P, and the weight - average molecular weight is 200,000 - 250,000.

[0073] The inventors found that during the debatching process, when the inlet flow rate of the polymerization liquid and the inlet flow rate of the solvent vapor satisfy a specific relationship, a better debatching effect can be obtained. Specifically, the inlet flow rate Q 1 of the carbon fiber polymerization liquid entering the debatching device and the inlet flow rate Q 2 of the solvent vapor entering the debatching device satisfy:

[0074] Q 2 ≥k×Q 1 ×m×α×1000

[0075] wherein, the unit of Q 1 is m 3 / h, and the unit of Q 2The unit of is L / h, m is the mass percentage of the residual monomer in the carbon fiber polymerization solution; α is the flow coefficient of the solvent vapor, and the value range of α is 1.0 - 1.2; k is the proportionality coefficient, and the value range of k is 1.5 - 1.9.

[0076] Exemplarily, k = 1.60, 1.65, 1.70, 1.72, 1.74, 1.75, 1.80, 1.85. For example, k = 1.737.

[0077] Preferably, Q 1 is 3 - 5m 3 / h.

[0078] When 3.0m 3 / h ≤ Q 1 <3.7m 3 / h, preferably, the value of k is 1.8 - 1.9.

[0079] When 3.7m 3 / h ≤ Q 1 <4.4m 3 / h, preferably, the value of k is 1.7 - 1.8.

[0080] When 4.4m 3 / h ≤ Q 1 ≤5.0m 3 / h, preferably, the value of k is 1.6 - 1.7.

[0081] In one embodiment, Q 1 =3m 3 / h, m = 10%, α = 1.0, k = 1.9, then when Q 2 ≥570L / h, after testing, the acrylonitrile (AN) residual monomer in the polymerization solution after monomer removal is less than 100ppm.

[0082] In one embodiment, Q 1 =4m 3 / h, m = 10%, α = 1.1, k = 1.73, then when Q 2 ≥760L / h, after testing, the acrylonitrile (AN) residual monomer in the polymerization solution after monomer removal is less than 100ppm.

[0083] In one embodiment, Q 1 =5m 3 / h, m = 9%, α = 1.2, k = 1.60, then when Q 2 ≥860L / h, after testing, the acrylonitrile (AN) residual monomer in the polymerization solution after monomer removal is less than 100ppm.

[0084] The above embodiments fully verify the relationship Q 2 ≥k×Q1 reliability of ×m×α×1000.

[0085] Exemplarily, during the degassing process, the solvent vapor is at least one of dimethyl sulfoxide, sodium thiocyanate, and N,N-dimethylformamide. The selected solvent vapor is the same as the solvent in the carbon fiber polymerization solution.

[0086] In a third aspect, the present invention provides a method for preparing a carbon fiber spinning solution, comprising:

[0087] Preparing an acrylonitrile-based polymerization solution;

[0088] Performing subsequent treatment on the acrylonitrile-based polymerization solution to obtain a carbon fiber spinning solution; the subsequent treatment includes degassing treatment; the degassing treatment includes degassing the acrylonitrile-based polymerization solution using the degassing device described in the first aspect or the degassing method described in the second aspect.

[0089] In some embodiments, the steps of the method for preparing the carbon fiber spinning solution include:

[0090] Adding a material containing acrylonitrile, comonomer, and solvent to a polymerization device;

[0091] According to the viscosity change of the material, determining the timing of adding the remaining initiator after polymerization starts and the timing of terminating the reaction, and controlling the target molecular weight of the acrylonitrile-based polymerization solution by controlling the material temperature and the proportion of the remaining initiator in the total initiator;

[0092] Performing degassing treatment on the acrylonitrile-based polymerization solution that meets the target molecular weight; the degassing treatment includes degassing the acrylonitrile-based polymerization solution using the degassing device described in the first aspect or the degassing method described in the second aspect;

[0093] Performing ammoniation treatment on the degassed acrylonitrile-based polymerization solution.

[0094] Compared with the prior art, in the present invention, the initiator is added in batches during the polymerization reaction. According to the change in the viscosity of the material, the appropriate timing for adding the remaining initiator after the polymerization starts is determined, and through the coordinated control of the material temperature and the proportion of the remaining initiator in the total amount of the initiator, the molecular weight of the polymer is effectively regulated to reach the target level. The present invention accurately determines the optimal timing for adding the remaining initiator after the polymerization starts by monitoring the viscosity. Compared with traditional indicators such as temperature and reaction time, the change in the viscosity of the material can more accurately reflect the progress of the reaction; while traditional indicators such as conversion rate, although they can be used as one of the evaluation indicators of the reaction degree, the determination of the conversion rate is too cumbersome and time-consuming. Obtaining each conversion rate requires sampling from the material in the reaction process and drying it for several hours to obtain a solid, and then calculating the conversion rate, which is difficult to apply in industrial production. Compared with traditional indicators such as conversion rate, the viscosity index of the present invention is more operable. In actual application, it can conveniently grasp the optimal timing for adding the initiator, thereby significantly improving the stability of the viscosity and molecular weight of different batches of polymerization solutions, and thus laying a solid foundation for the subsequent preparation of high-performance carbon fibers.

[0095] In some embodiments, the determining the timing for adding the remaining initiator and the timing for terminating the reaction according to the change in the viscosity of the material includes:

[0096] Raise the temperature to the polymerization temperature and add part of the initiator;

[0097] Monitor the viscosity of the material in real time:

[0098] When the viscosity of the material reaches the first viscosity threshold, add the remaining initiator. When the viscosity of the material reaches the second viscosity threshold, terminate the reaction to obtain an acrylonitrile-based polymerization solution with the target molecular weight; the first viscosity threshold < the second viscosity threshold.

[0099] Preferably, the first viscosity threshold is 200P - 400P; and / or, the second viscosity threshold is 600P - 1000P.

[0100] Preferably, the polymerization temperature is 50 - 60°C. When the viscosity of the material reaches the first viscosity threshold, raise the temperature of the material to the target temperature of 60 - 70°C.

[0101] Preferably, the proportion of the remaining initiator in the total amount of the initiator is 20 - 40%.

[0102] Based on the above advantages in determining the timing for adding the batch initiator according to the viscosity change, etc., the present invention can effectively reduce the number of molecular chain end groups in the polymerization reaction, increase the molecular chain length, reduce the number of small molecules, obtain a polymerization stock solution with a high molecular weight, and reduce the molecular weight distribution width by controlling the viscosity threshold for adding the remaining initiator, the viscosity threshold for termination, the polymerization temperature, the temperature rise to the target temperature, the proportion of the remaining initiator in the total amount of the initiator, etc.

[0103] Exemplarily, the polymerization temperature is 52 °C, 54 °C, 56 °C, 58 °C. Preferably, the polymerization temperature is 55 - 60 °C.

[0104] Exemplarily, the target temperature is 62 °C, 64 °C, 67 °C, 69 °C. Preferably, the target temperature is 66 - 68 °C.

[0105] Exemplarily, the first viscosity threshold is 250 P, 280 P, 330 P, 350 P, 380 P. More preferably, the first viscosity threshold is 300 P - 400 P.

[0106] Exemplarily, the second viscosity threshold is 650 P, 700 P, 750 P, 800 P, 850 P, 900 P, 950 P. Preferably, the second viscosity threshold is 750 P - 950 P.

[0107] Exemplarily, the proportion of the remaining initiator in the total initiator is 23%, 25%, 27%, 30%, 33%, 35%, 37%. Preferably, the proportion of the remaining initiator in the total initiator is 30 - 40%. It should be noted that by precisely controlling the viscosity threshold, the material temperature (polymerization temperature and the target temperature to which the temperature is raised when the viscosity threshold is reached), and the proportion of the remaining initiator in the total initiator, while obtaining a polymer solution with high molecular weight and narrow distribution, the micro - regulation of the molecular weight of the polymer solution can be achieved.

[0108] In some embodiments, the polymer solution is an acrylonitrile - based polymer solution, the polymerization temperature is 50 - 52 °C, the first viscosity threshold is 200 P - 250 P, when the material viscosity reaches the first viscosity threshold, the target temperature to which the temperature is raised is 68 - 70 °C, the proportion of the remaining initiator in the total initiator is 35 - 40%; the second viscosity threshold is 620 - 650 P; the molecular weight (M W ) of the obtained acrylonitrile - based polymer solution is 200,000 - 220,000, and the polydispersity index (PDI) is 2.5 - 3.0.

[0109] In some embodiments, the polymer solution is an acrylonitrile - based polymer solution, the polymerization temperature is 54 - 56 °C, the first viscosity threshold is 250 P - 300 P, when the material viscosity reaches the first viscosity threshold, the target temperature to which the temperature is raised is 64 - 66 °C, the proportion of the remaining initiator in the total initiator is 35 - 40%; the second viscosity threshold is 700 - 750 P; the molecular weight (M W ) of the obtained acrylonitrile - based polymer solution is 210,000 - 230,000, and the polydispersity index (PDI) is 2.2 - 2.7.

[0110] In some embodiments, the polymerization solution is an acrylonitrile-based polymerization solution, the polymerization temperature is 58 - 60 °C, the first viscosity threshold is 250 P - 300 P. When the viscosity of the material reaches the first viscosity threshold, the target temperature to which it is heated is 60 - 62 °C, and the proportion of the remaining initiator in the total amount of initiator is 35 - 40%; the second viscosity threshold is 700 - 750 P; the molecular weight (M W ) of the obtained acrylonitrile-based polymerization solution is 220,000 - 240,000, and the polydispersity index (PDI) is 2.2 - 2.7.

[0111] In some embodiments, the polymerization solution is an acrylonitrile-based polymerization solution, the polymerization temperature is 54 - 56 °C, the first viscosity threshold is 300 P - 350 P. When the viscosity of the material reaches the first viscosity threshold, the target temperature to which it is heated is 64 - 66 °C, and the proportion of the remaining initiator in the total amount of initiator is 30 - 35%; the second viscosity threshold is 800 - 850 P; the molecular weight (M W ) of the obtained acrylonitrile-based polymerization solution is 230,000 - 250,000, and the polydispersity index (PDI) is 2.0 - 2.5.

[0112] In some embodiments, the polymerization solution is an acrylonitrile-based polymerization solution, the polymerization temperature is 54 - 56 °C, the first viscosity threshold is 350 P - 400 P. When the viscosity of the material reaches the first viscosity threshold, the target temperature to which it is heated is 64 - 66 °C, and the proportion of the remaining initiator in the total amount of initiator is 30 - 35%; the second viscosity threshold is 900 - 950 P; the molecular weight (M W ) of the obtained acrylonitrile-based polymerization solution is 230,000 - 250,000, and the polydispersity index (PDI) is 2.0 - 2.5.

[0113] In some embodiments, the step of real-time monitoring the viscosity of the material includes: setting a material reflux pipeline, real-time monitoring the pressure of the material at a fixed position in the reflux pipeline, and obtaining the real-time monitored viscosity of the material according to the real-time viscosity value converted from the pressure value.

[0114] Specifically, the material is led out from the polymerization device, the material flows through the reflux pipeline at a constant temperature and a constant flow rate, and finally converges back to the polymerization device; by real-time monitoring the pressure of the material at a fixed position in the reflux pipeline, and combining with the pressure-viscosity relationship formula, the pressure value is converted into a real-time viscosity value.

[0115] Furthermore, the determination method of the pressure-viscosity relationship formula includes: by setting multiple data acquisition times, at each data acquisition time, recording the pressure value at the fixed position of the reflux pipeline and the viscosity value obtained by the experimental method, performing mathematical fitting of the pressure value and the viscosity value, and establishing the pressure-viscosity relationship formula.

[0116] Specifically, the steps for obtaining the viscosity value by the experimental method include: sampling from within the polymerization device and measuring the viscosity of the sample using a viscosity measuring instrument. Preferably, the sampling position is adjacent to the position where the material is led out of the polymerization device. Exemplarily, the viscosity measuring instrument includes a falling ball viscometer, a rotational viscometer, a capillary viscometer, a rheometer, a vibrating viscometer, and an ultrasonic viscometer.

[0117] To ensure the reliability and consistency of the pressure measurement results, the step of flowing the material through the reflux pipeline at a constant temperature and a constant flow rate includes: placing the reflux pipeline in a constant temperature circulating water system and setting a constant speed gear pump on the reflux pipeline. By means of the constant temperature circulating water system, it is ensured that the temperature of the material remains constant during the flowing process, and by controlling the rotational speed of the gear pump, it can be ensured that the material flows through the pipeline at a constant flow rate.

[0118] It can be understood that under the conditions of a constant flow rate, a constant temperature, and a pipeline of a fixed length (constant pipeline resistance), by measuring the pressure generated when the polymerization liquid flows through a fixed position of the reflux pipeline and combining with the pressure-viscosity relationship formula, the viscosity of the material can be obtained. Preferably, the above real-time monitoring of the material viscosity is applicable to materials with a viscosity of 0 - 1000P.

[0119] Preferably, the length of the reflux pipeline is 0.5 - 1.5 meters, and the pipe diameter is 5 - 20 mm. Exemplarily, the length of the reflux pipeline is 1.0 meter, and the pipe diameter is 10 mm.

[0120] In some embodiments, for the acrylonitrile-based polymerization liquid obtained by polymerizing acrylonitrile and comonomers, the pressure-viscosity relationship formula is:

[0121] y = -0.045x 2 +13.78x - 106.8

[0122] where y is the viscosity measured by the falling ball method, with the unit of P; x is the pressure, with the unit of Kpa.

[0123] Exemplarily, the viscosity y is the viscosity measured by the falling ball method at 40 - 50 °C. For example, within the ±Δ time range near each data acquisition moment t, preferably Δ ≤ 10 min, the pressure values at a fixed position of the reflux pipeline are recorded N times, and samples are taken from within the polymerization device N times at the same time points as the recorded pressure values. Viscosity measurements are carried out at N temperature points within 40 - 50 °C. Through data fitting software (such as EXCEL, Matlab, or Python), the viscosity y and the pressure x are fitted, and the fitting criterion is: the coefficient of determination R 2 ≥ 95%, preferably R 2≥98%, a pressure-viscosity relationship is obtained, wherein the model type of the pressure-viscosity relationship includes at least one of exponential, linear, logarithmic, polynomial (2nd order and above), and power. For example, N is 3, and the test conditions are 40°C, 45°C, and 50°C, respectively. For example, Δ=8min, 5min, 2min, and 1min.

[0124] Preferably, the constant temperature is 40-50° C.; and / or the constant flow rate is 1-2 L / h.

[0125] Preferably, the position for leading the material out of the polymerization device is set at 10 to 20 cm below the lower end of the stirring device in the polymerization device, which is the position where the polymerization liquid has the best fluidity, so as to facilitate timely and accurate monitoring of the real-time viscosity of the polymerization liquid in the polymerization kettle.

[0126] In one embodiment, the step of real-time monitoring the pressure of the material at a fixed position of the return pipeline and converting the pressure value into a real-time viscosity value in combination with a pressure-viscosity relationship comprises: setting an online pressure-viscosity converter at a fixed position of the return pipeline, the online pressure-viscosity converter comprising a pressure detector and a processor;

[0127] The pressure detector is used to collect the pressure signal of the polymerization liquid in the reflux pipeline in real time, and transmit the pressure signal to the processor through the line; the processor converts the pressure signal into a viscosity value according to a preset pressure-viscosity relationship, and transmits the viscosity value through the line to a display arranged outside the polymerization device for real-time display.

[0128] Specifically, the ratio of the materials and the total amount of the initiator is, by weight, 20-24 parts of acrylonitrile, 1-2 parts of the comonomer, 73.65-78.85 parts of the solvent, and 0.15-0.35 parts of the total amount of the initiator. Preferably, the total amount of the initiator is 0.2-0.3 parts.

[0129] Optionally, the comonomer is one or a combination of itaconic acid, acrylic acid, methyl acrylate, methyl methacrylate, ethyl methacrylate, isobutyl acrylate, β-butyl itaconate, acrylamide, acrylamide oxime, hydroxyethyl acrylonitrile, α-chloroacrylonitrile or diacetone acrylamide. Exemplarily, the comonomer is itaconic acid.

[0130] Optionally, the initiator is at least one of azobisisobutyronitrile, azobisisoheptanenitrile, and dimethyl azobisisobutyrate. Exemplarily, the initiator is azobisisobutyronitrile (AIBN).

[0131] Optionally, the solvent is at least one of dimethyl sulfoxide, sodium thiocyanate, and N,N-dimethylformamide. Exemplarily, the solvent is dimethyl sulfoxide.

[0132] In some embodiments, the material further includes a molecular weight regulator; for example, the molecular weight regulator is isopropanol; taking acrylonitrile and comonomers as copolymerization components, the addition amount of the molecular weight regulator is 0.002-0.005% of the total mass of the copolymerization components.

[0133] Specifically, after the material is added to the polymerization device, before the polymerization is started, the material is stirred by a stirring device to make it uniformly mixed. The stirring device is located in the middle of the internal liquid in the polymerization kettle and stirs in the same direction.

[0134] Preferably, the stirring device includes a ribbon agitator and a scraping wall agitator.

[0135] Preferably, before the polymerization is started, the rotation speed of the stirring is 20-80 rpm, and the stirring time is 30-60 min. For example, the rotation speed of the stirring is 30 rpm, 40 rpm, 50 rpm, 60 rpm, 70 rpm. The stirring time is 35 min, 40 min, 45 min, 50 min, 55 min.

[0136] (a) For the ribbon agitator, it satisfies: S 1 =(50-70%)S 2 , S 1 =Π×(1 / 2D 1 ) 2 , D 1 is the outer diameter of the ribbon, and S 2 is the internal cross-sectional area of the polymerization kettle. For example, S 1 / S 2 =55%, 60%, 65%.

[0137] (b) For the scraping wall agitator, it satisfies: L≤10 mm, where L represents the gap between the scraping wall component (such as a scraper or a knife) of the scraping wall agitator and the inner wall of the polymerization kettle. As the polymerization reaction proceeds, the viscosity of the internal liquid in the polymerization kettle continuously increases and becomes a highly viscous liquid. By using a scraping wall agitator and controlling L, it effectively avoids the attachment of the highly viscous liquid on the inner wall of the polymerization kettle to form a wall-hanging rubber block.

[0138] During the stirring process, the proportion of the liquid level height h of the internal liquid in the polymerization kettle to the total height H of the polymerization kettle is 10%-90%. For example, h / H = 20%, 30%, 40%, 50%, 60%, 70%, 80%. Preferably, h / H = 80-90%.

[0139] By selecting the above preferred stirring device and stirring parameters, etc., it can efficiently ensure that the material is uniformly mixed before the polymerization is started.

[0140] Preferably, by weight, acrylonitrile is 22 - 24 parts, the comonomer is 1 - 2 parts, the solvent is 73.7 - 76.8 parts, the stirring speed is 40 - 60 rpm, and the stirring time is 30 - 45 min.

[0141] Preferably, by weight, acrylonitrile is 20 - 22 parts, the comonomer is 1 - 2 parts, the solvent is 74.7 - 77.8 parts, the stirring speed is 50 - 70 rpm, and the stirring time is 45 - 55 min.

[0142] Exemplarily, the uniformity of the material mixture is judged by the uniform temperature of the internal liquid in the polymerization kettle. Specifically, during the stirring process, when the temperature difference of the internal liquid in the polymerization kettle ≤ 1 °C, this is used as the judgment basis for uniform mixing.

[0143] Specifically, the polymerization reaction is carried out under the protection of an inert gas. The flow rate of the inert gas is 50 - 100 L / h; the pressure of the inert gas ≤ 0.1 Mpa. Oxygen in the air has an inhibiting effect on polymerization. The inert gas can isolate oxygen. Using an inert gas with a suitable flow rate and pressure helps the polymerization reaction.

[0144] Preferably, the inert gas enters the polymerization kettle from one side of the top of the polymerization kettle and flows out of the polymerization kettle from the other side of the top of the polymerization kettle, so that the original air in the polymerization kettle can be better replaced. The inert gas is selected from at least one of nitrogen, argon or helium.

[0145] Exemplarily, the flow rate of the inert gas is 60 L / h, 70 L / h, 75 L / h, 85 L / h.

[0146] Exemplarily, the pressure of the inert gas is 0.07 Mpa, 0.05 Mpa, 0.04 Mpa, 0.02 Mpa, 0.01 Mpa.

[0147] Preferably, the flow rate of the inert gas is 80 - 90 L / h; the pressure of the inert gas is 0.06 - 0.08 Mpa. By precisely controlling the flow rate and pressure of the inert gas, it is beneficial to polymerize to obtain a polymer solution with high molecular weight and narrow distribution.

[0148] Preferably, the initiator is pre - dissolved in the solvent and then added to the polymerization device in batches, which helps to ensure that the initiator reaches a uniform distribution more quickly in the entire reaction system, improves the uniformity of the polymerization reaction rate at different positions in the polymerization device, and is beneficial to obtaining a polymer solution with high molecular weight and narrow distribution. Preferably, for the case where the initiator is 0.15 - 0.35 parts, the solvent used to dissolve the initiator is 5 - 10 parts.

[0149] Specifically, after the polymerization is started, the materials in the polymerization kettle are continuously stirred at a stirring speed of 30 - 80 rpm. Exemplarily, after the polymerization is started, the stirring speed is 35 rpm, 40 rpm, 45 rpm, 50 rpm, 55 rpm, 60 rpm, 65 rpm, 70 rpm, 75 rpm.

[0150] Preferably, after the polymerization is started and before the remaining initiator is added, the stirring speed is 30 - 60 rpm, more preferably 40 - 60 rpm. After the remaining initiator is added, the stirring speed is 50 - 80 rpm, more preferably 50 - 70 rpm.

[0151] In the ammoniation treatment, in the storage tank of the ammoniation device, the polymerization liquid remains flowing and the temperature is controlled at 60 - 65 °C, which is the optimal temperature range for the ammoniation of the acrylonitrile - based polymerization liquid. Specifically, the polymerization liquid flows into the storage tank of the ammoniation device from the upper part and flows out from the lower part of the storage tank.

[0152] To ensure that groups such as carboxyl groups on the molecular chain in the polymerization liquid are effectively converted into hydrophilic groups such as carboxamide through ammoniation, preferably, in the ammoniation treatment, according to the flow rate Q of the polymerization liquid 3 and combined with the following relationship: M = Q 3 ×n, the mass M of ammonia gas required to be introduced per 1 kg of the polymerization liquid is determined; where the unit of M is mg, and the unit of Q 3 is m 3 / h, and the value range of n is 1.25 - 3.0.

[0153] During the ammoniation process, the appropriate range of ammonia gas introduction amount is set according to the flow rate of the polymerization liquid and combined with the quantitative relationship, so as to accurately control the ammonia gas introduction amount, thereby ensuring the ammoniation effect, improving the ammoniation uniformity, enhancing the hydrophilicity of polyacrylonitrile, stabilizing the ammoniation degree, extending the service life of the spinning solution, and further improving the performance of carbon fiber.

[0154] Exemplarily, n = 1.5, 1.8, 2.1, 2.4, 2.7.

[0155] Preferably, the value range of Q 3 is 3 - 5 m 3 / h.

[0156] When 3.0 m 3 / h ≤ Q 3 <3.5 m 3 / h, preferably, the value range of n is 2.0 - 2.7.

[0157] When 3.5 m 3 / h ≤ Q 3 <4.3 m 3 / h, preferably, the value range of n is 1.25 - 1.75.

[0158] When 4.3 m 3 / h ≤ Q 3 ≤ 5.0 m 3 / h, preferably, the value range of n is 1.6 - 2.0.

[0159] In one embodiment, Q 3 = 3 m 3 / h, when M satisfies 6 - 8 mg, after testing, the pH of the ammoniated spinning solution is 8 - 10, and the ammoniation effect is good.

[0160] In one embodiment, Q 3 = 4 m 3 / h, when M satisfies 5 - 7 mg, after testing, the pH of the ammoniated spinning solution is 8 - 10, and the ammoniation effect is good.

[0161] In one embodiment, Q 3 = 5 m 3 / h, when M satisfies 8 - 10 mg, after testing, the pH of the ammoniated spinning solution is 8 - 10, and the ammoniation effect is good.

[0162] Preferably, the ammonia gas introduction time is controlled within 5 - 8 hours.

[0163] In the ammoniation treatment, based on the material ratio provided by the present invention, according to the flow rate Q 3 of the polymerization solution and combined with the following relational expression: M = Q 3 × n to accurately control the ammonia gas introduction amount, which can not only ensure good ammoniation effect, but also save ammonia gas and ammoniation treatment time.

[0164] Preferably, in the ammoniation treatment, an inclined paddle stirrer is used to stir the polymerization solution. The inclined paddle stirrer includes a plurality of inclined stirring paddles. The inclination angle of the inclined stirring paddles is 40 - 50°, and the inclined stirring paddles are rectangular paddles with a length of L and satisfying πL 2 = (50 - 70%)S 4 , where S 4 is the cross-sectional area of the storage tank in the ammoniation device. During the ammoniation treatment, the stirring speed is controlled within 30 - 50 r / min. Exemplarily, during ammoniation, the stirring speed is controlled at 35 r / min, 40 r / min, 45 r / min.

[0165] Using the inclined paddle stirrer to lift the polymerization solution upward can generate strong axial flow, causing the polymerization solution to form an up-and-down circulating flow during stirring. This flow pattern helps the ammonia gas to be better dispersed in the polymerization solution, improving the mass transfer efficiency and ammoniation effect. By accurately controlling the structural parameters of the inclined paddle stirrer, the up-and-down circulating flow can be better promoted, further improving the mass transfer efficiency and ammoniation effect.

[0166] Preferably, the ammoniation treatment is carried out under slightly positive pressure, so that ammonia can diffuse more effectively and contact the polymerization solution fully, while ensuring the safety of the system. Specifically, during the ammoniation process, a pressure slightly higher than the external atmospheric pressure, i.e., slightly positive pressure, is applied inside the storage tank. The slightly positive pressure is 0 - 2000 Pa, that is, the pressure inside the storage tank is 0 - 2000 Pa higher than the external atmospheric pressure. More preferably, the slightly positive pressure is 100 - 1000 Pa. Exemplarily, the slightly positive pressure is 50 Pa, 200 Pa, 500 Pa, 800 Pa, 1300 Pa, 1500 Pa, 1800 Pa.

[0167] By using the ammoniation treatment provided in the above embodiments of the present invention, the pH of the obtained carbon fiber spinning solution can be guaranteed to be 8 - 10, further 8.4 - 9.8, and preferably 8.9 - 9.5.

[0168] In the fourth aspect, the present invention provides a carbon fiber spinning solution, which is prepared by the preparation method described in the third aspect.

[0169] Specifically, the molecular weight M of the obtained acrylonitrile-based polymerization solution W is 200,000 - 250,000, the polydispersity index PDI is 2.0 - 3.0, the falling ball viscosity at 40 - 50 °C is 600 - 1000 P, the solid content in the polymerization solution is 19.0 - 21.0%, the polymerization conversion rate ≥ 90%, and the residual monomer content of the obtained acrylonitrile-based polymerization solution is ≤ 10%. After the degassing treatment, the residual monomer content of the acrylonitrile-based polymerization solution is ≤ 350 ppm. After the ammoniation treatment, the pH of the obtained carbon fiber spinning solution is 8 - 10.

[0170] In some embodiments, the molecular weight M of the obtained acrylonitrile-based polymerization solution W is 210,000 - 250,000, the polydispersity index PDI is 2.1 - 2.6, the falling ball viscosity at 40 - 50 °C is 620 - 910 P, the solid content in the polymerization solution is 19.2 - 20.6%, the polymerization conversion rate is 92 - 95%, the residual monomer content of the obtained acrylonitrile-based polymerization solution is ≤ 3%, further, the residual monomer content of the obtained acrylonitrile-based polymerization solution is ≤ 2%, further, the residual monomer content of the obtained acrylonitrile-based polymerization solution is ≤ 1%. After the degassing treatment, the residual monomer content of the acrylonitrile-based polymerization solution is < 100 ppm, more preferably, the residual monomer content after degassing is less than 50 ppm, further, the residual monomer content after degassing is less than 30 ppm. After the ammoniation treatment, the pH of the obtained carbon fiber spinning solution is 8.4 - 9.8, and preferably 8.9 - 9.5.

[0171] Fifth aspect, the present invention provides a production device for carbon fiber spinning solution, and the production device is used for the carbon fiber spinning solution obtained by the preparation method as described in the third aspect or the production and preparation of the carbon fiber spinning solution as described in the fourth aspect.

[0172] Specifically, the production device includes an ammoniation device, a polymerization device, and the degassing device described in the first aspect.

[0173] (1) Ammoniation device:

[0174] The ammoniation device 200 includes a storage tank and an inclined paddle stirrer 21 arranged inside the storage tank; the inclined paddle stirrer 21 includes a plurality of stirring paddles 21a arranged in layers along the axial direction of the storage tank, and the plurality of stirring paddles are commonly connected to the same rotating shaft 21b. Preferably, the plurality of stirring paddles are equally spaced along the axial direction of the storage tank.

[0175] Each stirring paddle includes a plurality of inclined stirring paddle blades. Preferably, the inclination angle of the inclined stirring paddle blades is 40 - 50°, and the inclined stirring paddle blades are rectangular paddle blades with a length of L and satisfying πL 2 =(50 - 70%)S 4 , S 4 is the cross-sectional area of the storage tank. Preferably, πL 2 =(50 - 55%)S 4 .

[0176] Exemplarily, the inclined paddle stirrer includes 2, 3 or 4 stirring paddles, and each stirring paddle includes at least two inclined stirring paddle blades. For example, each stirring paddle includes 3 or 4 inclined stirring paddle blades.

[0177] Preferably, the ammonia gas inlet 22 is arranged in the range of 1 / 5 to 2 / 5 of the height of the lower part of the storage tank, that is, the area between 1 / 5 height and 2 / 5 height upward from the bottom of the storage tank.

[0178] A polymerization liquid inlet 23 is arranged at the upper part or top of the storage tank, and a polymerization liquid outlet 24 is arranged at the lower part or bottom of the storage tank; the top end of the rotating shaft 21b of the inclined paddle stirrer is driven by a first motor 25.

[0179] (2) Polymerization device:

[0180] The polymerization device 300 includes a polymerization kettle and a stirring device 31 arranged inside the polymerization kettle, and the stirring device 31 is selected from a ribbon stirrer and a scraping wall stirrer.

[0181] For the ribbon stirrer, it satisfies: S 1 =(50 - 70%)S 2 , S 1 =Π×(1 / 2D 1 ) 2 , D1 is the outer diameter of the helical ribbon, S 2 is the inner cross-sectional area of the polymerization kettle. Exemplarily, S 1 / S 2 = 55%, 60%, 65%.

[0182] For the scraping wall stirrer, it satisfies: L ≤ 10 mm, where L represents the gap between the scraping wall component (such as a scraper or a knife) of the scraping wall stirrer and the inner wall of the polymerization kettle.

[0183] On one side of the top of the polymerization device 300, there is an inert gas inlet 32, and on the other side, there is an inert gas outlet 33. Preferably, both the inert gas inlet 32 and the inert gas outlet 33 are located within the range of 1 / 10 to 1 / 5 of the height of the polymerization device from the top downwards. The stirring device 31 is driven by a second motor 34.

[0184] In some embodiments, the polymerization device further includes a real-time viscosity monitoring device C, which includes a reflux pipeline. Both ends of the reflux pipeline are communicated with the inside of the polymerization kettle. An on-line pressure-viscosity converter 35 is arranged on the reflux pipeline. The on-line pressure-viscosity converter includes a pressure detector and a processor. The pressure detector is arranged at a fixed position of the reflux pipeline for real-time collection of the pressure signal of the polymerization liquid in the pipeline. The pressure detector is connected to the processor through a line. The processor is used to convert the collected pressure signal into a viscosity value. Figure 3 where T represents the temperature monitoring component and P represents the pressure monitoring component.

[0185] Further, the processor of the real-time viscosity monitoring device C is connected to a display arranged outside the polymerization device through a line. After the processor converts the collected pressure signal into a viscosity value, it transmits the data to the display through the line, so as to display the viscosity of the polymerization liquid in real time.

[0186] Preferably, a constant-speed gear pump 36 is arranged on the reflux pipeline, and a circulating water system is arranged outside the reflux pipeline. For example, the circulating water system is a water tank. The constant-temperature circulating water enters from one side of the water tank and flows out from the other side. Exemplarily, the constant-temperature circulating water enters the water tank from the circulating water inlet 37 at the bottom of the water tank and flows out of the water tank from the circulating water outlet 38 at the top of the water tank. The constant-speed gear pump and the circulating water system can ensure the constant temperature and flow rate of the polymerization liquid in the reflux pipeline.

[0187] In the method for preparing the carbon fiber spinning solution provided by the embodiments of the present invention, preferably, a material containing acrylonitrile, comonomer and solvent is added to the above-mentioned polymerization device 300. The degassing treatment is carried out by using the above-mentioned degassing device 100. The ammoniation treatment is carried out by using the above-mentioned ammoniation device 200.

[0188] It can be understood that the acrylonitrile-based polymerization solution refers to a polymer solution mainly composed of acrylonitrile monomers and formed through a polymerization reaction (such as free radical polymerization).

[0189] The technical solution of the present invention will be further described in detail below in conjunction with specific examples and comparative examples.

[0190] Example 1:

[0191] This example provides a device 100 for removing monomers from a carbon fiber polymerization solution. The device 100 includes a tank A and a multi-layer perforated partition 11 arranged horizontally (i.e., perpendicular to the axial direction of the tank) inside the tank A. The multi-layer perforated partitions are arranged in parallel and equally spaced layers from top to bottom along the axial direction of the tank. Each layer of perforated partition includes a fixed end on one side and a suspended end on the other side. The fixed end is conformally fixed to the inner wall of the tank, and the suspended end on the other side extends freely. The suspended end of one layer of perforated partition is located on one side of the axial direction of the tank, and the suspended ends of adjacent layers of perforated partitions are located on the other side of the axial direction of the tank. The suspended ends of the multi-layer perforated partitions form an alternating staggered layout in space.

[0192] The area of each layer of perforated partition accounts for 75% of the cross-sectional area of the tank at that layer position, and the remaining 25% serves as a smooth channel for the flow of the polymerization solution; the holes of adjacent layers of perforated partitions are arranged in an alternating staggered manner, and the misalignment distance between the centers of the corresponding holes of adjacent layers is 10 mm; the pore size of each layer of perforated partition is 1.0 mm, the pore spacing is 20 mm, and the holes are arranged in a circular array; the thickness of each layer of perforated partition is 6 mm.

[0193] Inside the tank A, the distance between the first layer of perforated partition and the last layer of perforated partition accounts for 1 / 2 of the total height of the tank; a polymerization solution inlet 12 is provided at the top of the tank A, and a perforated distribution plate 13 is provided between the polymerization solution inlet 12 and the adjacent first layer of perforated partition, and the distribution plate 13 is arranged parallel to the first layer of perforated partition; the area ratio of the distribution plate 13 to the first layer of perforated partition is 30%, and the ratio of the distance between the upper surface of the distribution plate 13 and the lower end of the polymerization solution inlet 12 to the distance between the lower end of the polymerization solution inlet 12 and the upper surface of the first layer of perforated partition is 50%.

[0194] A solvent vapor inlet is provided at the lower part of the tank body A. The monomer removal device further includes a solvent vaporizer B. The top of the solvent vaporizer B is connected to the solvent vapor inlet through a pipeline. A solvent inlet 14 is provided at the bottom of the solvent vaporizer B. A coil 15 is provided inside the solvent vaporizer B. One end of the coil 15 is connected to a coil inlet 15a provided at the upper part of the solvent vaporizer, and the other end of the coil 15 is connected to a coil outlet 15b provided at the lower part of the solvent vaporizer; a polymerized liquid discharge port 18 is provided at the bottom of the tank body A; the solvent is vaporized into solvent vapor 16 by heating in the solvent vaporizer B and enters the storage tank from the solvent vapor inlet; a vacuum extraction port 17 is provided at the upper part of the tank body A; the monomer removal device further includes a liquid ring type vacuum jet device, which is connected to the vacuum extraction port 17 through a pipeline, so as to provide a stable negative pressure inside the tank body A in the monomer removal device and discharge the solvent vapor carrying monomers.

[0195] Example 2:

[0196] The difference between this example and Example 1 is that the area of each perforated partition accounts for 85% of the cross-sectional area of the tank body at that layer position, and the remaining 15% serves as a smooth channel for the flow of the polymerized liquid; the dislocation distance between the corresponding hole centers of adjacent layers is 20 mm; inside the tank body A, the distance between the first perforated partition and the last perforated partition accounts for 70% of the total height of the tank body; the area ratio of the distribution plate 13 to the first perforated partition is 50%, and the ratio of the distance between the upper surface of the distribution plate 13 and the lower end of the polymerized liquid feed port 12 to the distance between the lower end of the polymerized liquid feed port 12 and the upper surface of the first perforated partition is 30%.

[0197] Preparation Example 1:

[0198] This preparation example provides a method for preparing an acrylonitrile-based polymerized liquid, including the following steps:

[0199] Material preparation: By weight, 20 parts of acrylonitrile, 1 part of itaconic acid, 0.2 part of azobisisobutyronitrile (AIBN), and 73.7 parts of dimethyl sulfoxide; 0.2 part of AIBN is pre-dissolved in 8 parts of dimethyl sulfoxide as an initiator for free radical polymerization;

[0200] Add acrylonitrile, itaconic acid, and dimethyl sulfoxide into the polymerization device, and stir the materials in the polymerization device through a scraping wall stirrer, L = 10 mm, the stirring speed is 20 rpm, and the stirring time is 60 min; the proportion of the liquid level height h of the inner liquid in the polymerization device to the total height H of the polymerization device is 80%;

[0201] When the temperature difference of the material ≤ 1°C and it is heated to 54°C, first add part of the initiator, and the proportion of the part of the initiator in the total amount of the initiator is 60%; monitor the viscosity of the material in real time. When the viscosity of the material reaches the first viscosity threshold of 250 P, heat the material to the target temperature of 64°C and add the remaining 40% of the initiator; when the viscosity of the material reaches the second viscosity threshold of 620 P, terminate the reaction; the polymerization is carried out under nitrogen protection, the flow rate of nitrogen is 50 L / h, and the pressure is 0.1 Mpa. During the polymerization, the stirring speed is 30 rpm; the molecular weight and PDI of the acrylonitrile-based polymerization liquid obtained after polymerization are shown in Table 1, and it meets the target molecular weight.

[0202] Example 3-1:

[0203] This example provides a method for removing monomers from a carbon fiber polymerization liquid, including: performing monomer removal treatment on the acrylonitrile-based polymerization liquid that meets the target molecular weight obtained in Preparation Example 1; during the monomer removal treatment, the polymerization liquid enters from the top of the monomer removal device in Example 1 and is evenly distributed on the first layer of perforated partition plate through porous distribution, and successively passes through the second to fifth layers of perforated partition plates arranged alternately to perform gas-liquid exchange with the solvent vapor flowing upstream. At each layer of perforated partition plate, the polymerization liquid is divided into two parts: one part of the polymerization liquid flows through the holes on the perforated partition plate to the next layer of perforated partition plate or the polymerization liquid collection area, and the hole positions where the polymerization liquid flows out of the adjacent layer of perforated partition plate are different, and the other part of the polymerization liquid flows from the suspended end on the side of the partition plate to the next layer of perforated partition plate or the polymerization liquid collection area; among them, the monomer removal treatment is carried out at 500 Pa, the inlet temperature of the polymerization liquid is 50°C, and the inlet flow rate Q 1 is 3 m 3 / h; the inlet temperature of the solvent vapor is 80°C. The inlet flow rate of the solvent vapor is 80 L / h, and the pressure of the solvent vapor is 0.5 Mpa.

[0204] Example 3-2:

[0205] This example provides a method for preparing a carbon fiber spinning solution, including:

[0206] Preparing an acrylonitrile-based polymerization liquid through Preparation Example 1;

[0207] Performing monomer removal treatment on the acrylonitrile-based polymerization liquid prepared in Preparation Example 1 through Example 3-1;

[0208] Using the ammonia bubbling method, ammonia gas was introduced into the polymerized solution after the removal of monomers in Example 3-1 for ammoniation treatment; specifically, the temperature of the polymerized solution placed in the storage tank was adjusted to 60 °C, and then ammonia gas was introduced from the lower 1 / 5 of the storage tank. During the ammoniation process, the temperature was controlled at 60 °C, the slight positive pressure was 100 Pa, and a pitched blade agitator was used for stirring at a stirring speed of 55 r / min; the pitched blade agitator included 3 stirring paddles, and each stirring paddle included 3 rectangular pitched stirring blades with an inclination angle of 35°, and its length was L and satisfied πL 2 = 70% × S 4 , S 4 being the cross-sectional area of the storage tank; the flow rate Q 3 of the polymerized solution was 3 m3 / h, and the amount of ammonia gas required was calculated according to 4.0 mg of ammonia gas introduced per 1 kg of the polymerized solution.

[0209] Preparation Example 2:

[0210] The difference between this preparation example and Preparation Example 1 is that when the temperature difference of the material ≤ 1 °C and the temperature is raised to 58 °C, part of the initiator is added first, and the proportion of the part of the initiator in the total amount of the initiator is 65%; the viscosity of the material is monitored in real time. When the viscosity of the material reaches the first viscosity threshold of 300 P, the material is heated to the target temperature of 62 °C, and the remaining 35% of the initiator is added; when the viscosity of the material reaches the second viscosity threshold of 710 P, the reaction is terminated. The remaining steps and parameters are similar to those in Preparation Example 1.

[0211] Example 4-1:

[0212] The difference between this example and Example 3-1 is that the acrylonitrile-based polymerized solution meeting the target molecular weight obtained in Preparation Example 2 is subjected to monomer removal treatment; in the monomer removal treatment, the inlet flow rate of the solvent vapor is 100 L / h; the remaining steps and parameters are similar to those in Example 3-1.

[0213] Example 4-2:

[0214] The difference between this example and Example 3-2 is that the acrylonitrile-based polymerized solution is prepared by Preparation Example 2, and the acrylonitrile-based polymerized solution prepared by Preparation Example 2 is subjected to monomer removal treatment through Example 4-1;

[0215] in the ammoniation treatment, the amount of ammonia gas required is calculated according to 6 mg of ammonia gas introduced per 1 kg of the polymerized solution; the remaining steps and parameters are similar to those in Example 3-2.

[0216] Preparation Example 3:

[0217] The difference between this preparation example and Preparation Example 1 is as follows: when the temperature difference between materials ≤ 1°C and the temperature is raised to 54°C, a part of the initiator is added first, and the proportion of this part of the initiator in the total amount of initiator is 70%; the viscosity of the materials is monitored in real time. When the viscosity of the materials reaches the first viscosity threshold of 350 P, the temperature of the materials is raised to the target temperature of 66°C, and the remaining 30% of the initiator is added; when the viscosity of the materials reaches the second viscosity threshold of 760 P, the reaction is terminated. The remaining steps and parameters are similar to those of Preparation Example 1.

[0218] Example 5-1:

[0219] The difference between this example and Example 3-1 is as follows: the acrylonitrile-based polymerization solution meeting the target molecular weight obtained in Preparation Example 3 is subjected to degassing treatment; in the degassing treatment, the degassing device of Example 2 is used for degassing treatment, and the inlet flow rate of the solvent vapor is 100 L / h. The remaining steps and parameters are similar to those of Example 3-1.

[0220] Example 5-2:

[0221] The difference between this example and Example 3-2 is as follows: the acrylonitrile-based polymerization solution is prepared through Preparation Example 3, and the acrylonitrile-based polymerization solution prepared in Preparation Example 3 is subjected to degassing treatment through Example 5-1;

[0222] In the ammoniation treatment, each stirring paddle includes 3 rectangular inclined stirring paddle blades with an inclination angle of 35°, and its length is L and satisfies πL 2 = 50% × S 4 , S 4 is the cross-sectional area of the storage tank, and the amount of ammonia required is calculated according to 5 mg of ammonia introduced per 1 kg of the polymerization solution; the remaining steps and parameters are similar to those of Example 3-2.

[0223] Preparation Example 4:

[0224] The difference between this preparation example and Preparation Example 1 is as follows: when the temperature difference between materials ≤ 1°C and the temperature is raised to 55°C, a part of the initiator is added first, and the proportion of this part of the initiator in the total amount of initiator is 68%; the viscosity of the materials is monitored in real time. When the viscosity of the materials reaches the first viscosity threshold of 320 P, the temperature of the materials is raised to the target temperature of 65°C, and the remaining 32% of the initiator is added; when the viscosity of the materials reaches the second viscosity threshold of 840 P, the reaction is terminated; the remaining steps and parameters are similar to those of Preparation Example 1.

[0225] Example 6-1:

[0226] The difference between this example and Example 3-1 is as follows: the acrylonitrile-based polymerization solution meeting the target molecular weight obtained in Preparation Example 4 is subjected to degassing treatment; in the degassing treatment, the degassing device of Example 2 is used for degassing treatment, and the inlet flow rate of the solvent vapor is 80 L / h; the remaining steps and parameters are similar to those of Example 3-1.

[0227] Example 6-2:

[0228] The difference between this example and Example 3-2 is that: the acrylonitrile-based polymerization liquid is prepared through Preparation Example 4, and the acrylonitrile-based polymerization liquid obtained from Preparation Example 4 is subjected to monomer removal treatment through Example 6-1;

[0229] In the ammoniation treatment, each stirring paddle includes 3 rectangular inclined stirring paddle blades with an inclination angle of 45°, and its length is L and satisfies πL 2 = 60%×S4, where S4 is the cross-sectional area of the storage tank, and the amount of ammonia required is calculated according to 5 mg of ammonia introduced per 1 kg of polymerization liquid; the remaining steps and parameters are similar to those in Example 3-2.

[0230] Preparation Example 5:

[0231] The difference between this preparation example and Preparation Example 1 is that: when the material temperature difference ≤ 1°C and the temperature is raised to 56°C, part of the initiator is added first, and the proportion of part of the initiator in the total amount of initiator is 65%; the material viscosity is monitored in real time. When the material viscosity reaches the first viscosity threshold of 300 P, the material is heated to the target temperature of 64°C, and the remaining 35% of the initiator is added; when the material viscosity reaches the second viscosity threshold of 810 P, the reaction is terminated; the remaining steps and parameters are similar to those in Preparation Example 1.

[0232] Example 7-1:

[0233] The difference between this example and Example 3-1 is that: the acrylonitrile-based polymerization liquid meeting the target molecular weight obtained from Preparation Example 5 is subjected to monomer removal treatment; in the monomer removal treatment, the monomer removal device of Example 2 is used for monomer removal treatment, and the inlet flow rate Q of the polymerization liquid 1 is 4 m 3 / h, and the inlet flow rate of the solvent vapor is 170 L / h; the remaining steps and parameters are similar to those in Example 3-1.

[0234] Example 7-2:

[0235] The difference between this example and Example 3-2 is that: the acrylonitrile-based polymerization liquid is prepared through Preparation Example 5, and the acrylonitrile-based polymerization liquid obtained from Preparation Example 5 is subjected to monomer removal treatment through Example 7-1;

[0236] In the ammoniation treatment, the flow rate Q of the polymerization liquid 3 = 4 m3 / h, and the amount of ammonia required is calculated according to 6.0 mg of ammonia introduced per 1 kg of polymerization liquid. The remaining steps and parameters are similar to those in Example 3-2.

[0237] Preparation Example 6:

[0238] The difference between this preparation example and Preparation Example 1 is as follows: When the temperature difference between materials ≤ 1 °C and the temperature is raised to 54 °C, part of the initiator is added first, and the proportion of this part of the initiator in the total amount of initiator is 75%; the viscosity of the material is monitored in real time. When the viscosity of the material reaches the first viscosity threshold of 350 P, the temperature of the material is raised to the target temperature of 64 °C, and the remaining 25% of the initiator is added; when the viscosity of the material reaches the second viscosity threshold of 910 P, the reaction is terminated; the remaining steps and parameters are similar to those in Preparation Example 1.

[0239] Example 8-1:

[0240] The difference between this example and Example 3-1 is as follows: The acrylonitrile-based polymerization solution meeting the target molecular weight obtained in Preparation Example 6 is subjected to degassing treatment; in the degassing treatment, the degassing device of Example 2 is used for degassing treatment, and the inlet flow rate Q 1 of the polymerization solution is 5 m 3 / h, and the inlet flow rate of the solvent vapor is 250 L / h; the remaining steps and parameters are similar to those in Example 3-1.

[0241] Example 8-2:

[0242] The difference between this example and Example 3-2 is as follows: The acrylonitrile-based polymerization solution is prepared through Preparation Example 6, and the acrylonitrile-based polymerization solution prepared in Preparation Example 6 is subjected to degassing treatment through Example 8-1;

[0243] In the ammoniation treatment, the flow rate Q 3 of the polymerization solution = 5 m3 / h, and the amount of ammonia required is calculated according to 12.0 mg of ammonia introduced per 1 kg of the polymerization solution. The remaining steps and parameters are similar to those in Example 3-2.

[0244] Preparation Example 7:

[0245] The difference between this preparation example and Preparation Example 1 is as follows: When the temperature difference between materials ≤ 1 °C and the temperature is raised to 57 °C, part of the initiator is added first, and the proportion of this part of the initiator in the total amount of initiator is 70%; the viscosity of the material is monitored in real time. When the viscosity of the material reaches the first viscosity threshold of 350 P, the temperature of the material is raised to the target temperature of 67 °C, and the remaining 30% of the initiator is added; when the viscosity of the material reaches the second viscosity threshold of 620 P, the reaction is terminated; the polymerization is carried out under nitrogen protection, the flow rate of nitrogen is 80 L / h, and the pressure is 0.06 Mpa. During the polymerization, before adding the remaining initiator, the stirring speed is 50 rpm; after adding the remaining initiator, the stirring speed is 60 rpm. The remaining steps and parameters are similar to those in Preparation Example 1.

[0246] Example 9-1:

[0247] The difference between this example and Example 3-1 lies in that the acrylonitrile-based polymerization solution that meets the target molecular weight obtained in Preparation Example 7 is subjected to a degassing treatment; in the degassing treatment, the degassing device of Example 2 is used for degassing treatment, the inlet temperature of the polymerization solution is 67 °C, and the inlet flow rate Q 1 is 5 m 3 / h; the inlet temperature of the solvent vapor is 95 °C. The inlet flow rate of the solvent vapor is 100 L / h, and the pressure of the solvent vapor is 0.3 Mpa. The remaining steps and parameters are similar to those in Example 3-1.

[0248] Example 9-2:

[0249] The difference between this example and Example 3-2 lies in that the acrylonitrile-based polymerization solution is prepared through Preparation Example 7, and the acrylonitrile-based polymerization solution prepared in Preparation Example 7 is subjected to a degassing treatment through Example 9-1;

[0250] In the ammoniation treatment, the flow rate Q 3 of the polymerization solution = 5 m3 / h, and the amount of ammonia required is calculated according to 10.0 mg of ammonia introduced per 1 kg of the polymerization solution. The remaining steps and parameters are similar to those in Example 3-2.

[0251] Comparative Example 1:

[0252] The difference between this comparative example and Example 3-1 lies in that in the degassing treatment, the difference between the degassing device used and that in Example 1 is that the area of the perforated partition plate (abbreviated as the horizontal perforated partition plate) along the horizontal direction of each layer accounts for 50-79% of the cross-sectional area of the tank body at this layer position, and an inclined baffle is provided on each layer of the horizontal perforated partition plate. The included angle between the inclined baffle and the horizontal perforated partition plate is 10°-60°. The holes on the horizontal perforated partition plate are within the vertical projection range of the inclined baffle, and the connection line between the inclined baffle and the horizontal perforated partition plate is parallel to the chord corresponding to the two end points of the arc on the horizontal perforated partition plate.

[0253] Comparative Example 2:

[0254] The difference between this comparative example and Preparation Example 1 lies in that when the temperature difference of the material ≤ 1 °C and the temperature is raised to 70 °C, a part of the initiator is added, and the proportion of the part of the initiator in the total amount of the initiator is 55%. The viscosity of the material is monitored in real time. When the viscosity of the material reaches the first viscosity threshold of 150 P, the remaining 45% of the initiator is added; when the viscosity of the material reaches the second viscosity threshold of 630 P, the reaction is terminated. The remaining steps and parameters are similar to those in Preparation Example 1.

[0255] Comparative Example 3:

[0256] The difference between this comparative example and Preparation Example 1 is as follows: when the temperature difference between the materials ≤ 1°C and the temperature is raised to 50°C, part of the initiator is added, and the proportion of this part of the initiator in the total amount of the initiator is 85%. The viscosity of the material is monitored in real time. When the viscosity of the material reaches the first viscosity threshold of 450 P, the temperature of the material is raised to the target temperature of 55°C, and the remaining 15% of the initiator is added; when the viscosity of the material reaches the second viscosity threshold of 630 P, the reaction is terminated. The remaining steps and parameters are similar to those of Preparation Example 1.

[0257] Comparative Example 4:

[0258] The difference between this comparative example and Preparation Example 1 is as follows: when the temperature difference between the materials ≤ 1°C and the temperature is raised to 65°C, part of the initiator is added, and the proportion of this part of the initiator in the total amount of the initiator is 90%. The viscosity of the material is monitored in real time. When the viscosity of the material reaches the first viscosity threshold of 450 P, the remaining 10% of the initiator is added; when the viscosity of the material reaches the second viscosity threshold of 560 P, the reaction is terminated. The remaining steps and parameters are similar to those of Preparation Example 1.

[0259] Comparative Example 5:

[0260] The difference between this comparative example and Example 3-2 is as follows: in the ammoniation treatment, the amount of ammonia required is calculated according to 2.0 mg of ammonia introduced into every 1 kg of the polymerization solution; the remaining steps and parameters are similar to those of Example 3-2.

[0261] Comparative Example 6:

[0262] The difference between this comparative example and Example 3-2 is as follows: in the ammoniation treatment, the amount of ammonia required is calculated according to 14.0 mg of ammonia introduced into every 1 kg of the polymerization solution; the remaining steps and parameters are similar to those of Example 3-2.

[0263] Table 1 Test Results of Examples and Comparative Examples

[0264]

[0265] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A carbon fiber polymer liquid stripping device, characterized in that: The single-piece removal device (100) comprises a tank body and a multi-layer perforated partition plate (11) arranged in the tank body, wherein the multi-layer perforated partition plates are arranged in layers from top to bottom along the axial direction of the tank body, and each layer of perforated partition plates is perpendicular to the axial direction of the tank body, and each layer of perforated partition plates comprises a fixed end on one side and a suspended end on the other side, wherein the fixed end is fixed to the inner wall of the tank body, and the suspended end on the other side is freely extended, the suspended end of one layer of perforated partition plates is located on one side of the axial direction of the tank body, and the suspended end of an adjacent layer of perforated partition plates is located on the other side of the axial direction of the tank body, and the suspended ends of the multi-layer perforated partition plates form an alternating staggered layout in space.

2. The device for removing single pieces according to claim 1, characterized in that: The area of ​​each layer of perforated baffles accounts for 80%-90% of the cross-sectional area of ​​the tank body at that layer, and the remaining 10-20% serves as a smooth passage for the flow of the polymer solution.

3. The device for removing single pieces according to claim 1, characterized in that: The holes of adjacent layers of perforated partitions are distributed in staggered layers, and the positions of the holes on each layer of perforated partitions are offset relative to the positions of the holes on the directly adjacent layers of perforated partitions.

4. The single removal device according to claim 1, characterized in that: In the tank body, the distance between the first layer of perforated partitions and the last layer of perforated partitions accounts for 1 / 2 to 4 / 5 of the total height of the tank body.

5. The single removal device according to claim 1, characterized in that: A polymerization liquid feed port (12) is arranged at the top or upper part of the tank body, a distribution plate (13) with holes is arranged between the polymerization liquid feed port (12) and the adjacent first layer of perforated partition plate, and the distribution plate (13) is arranged in parallel with the first layer of perforated partition plate.

6. The device for removing single pieces according to claim 5, characterized in that: The area ratio of the distribution plate (13) to the first layer of perforated partition is 40%-60%; and / or, The ratio of the distance between the upper surface of the distribution plate (13) and the lower end of the polymerization liquid feed port (12) to the distance between the lower end of the polymerization liquid feed port (12) and the upper surface of the first layer of perforated partition plates is 15%-40%.

7. A method for removing single carbon fiber from a carbon fiber polymerization liquid, characterized in that: The carbon fiber polymer liquid is debonded using the debonding device described in any one of claims 1 to 6.

8. The method for getting rid of singleness according to claim 7, characterized in that: The liquid inlet flow rate Q1 of the carbon fiber polymer liquid entering the debonding device and the gas inlet flow rate Q2 of the solvent vapor entering the debonding device satisfy: Q2 ≥ k × Q1 × m × α × 1000 Among them, the unit of Q1 is m 3 / h, the unit of Q2 is L / h, m is the mass percentage of residual monomers in the carbon fiber polymerization liquid; α is the flow coefficient of solvent vapor, and the value range of α is 1.0-1.2; k is the proportional coefficient, and the value range of k is 1.5-1.

9.

9. The method for getting rid of singleness according to claim 7, characterized in that: The inlet temperature of the carbon fiber polymerization liquid is 50-70° C.; and / or, The inlet temperature of the solvent vapor is 80-100° C.; and / or, The carbon fiber polymer solution has an inlet viscosity of 600-1000P; and / or, The inlet pressure of the solvent vapor is 0.01-0.5 MPa.

10. A method for preparing a carbon fiber spinning solution, characterized in that: include: preparing acrylonitrile-based polymerizing liquid; The acrylonitrile-based polymer solution is subsequently treated to obtain a carbon fiber spinning solution; the subsequent treatment includes a single-removal treatment; the single-removal treatment includes removing singles from the acrylonitrile-based polymer solution using a single-removal device as described in any one of claims 1 to 6 or a single-removal method as described in any one of claims 7 to 9.

Images