A continuous directional fiber sizing device and method based on airflow splitting-electrostatic spray coupling

Abstract

This invention provides a continuous directional fiber sizing device and method based on airflow splitting-electrostatic spray coupling, relating to the field of fiber composite material preparation. The device includes: a liquid storage and circulation system comprising an upper liquid storage tank, a lower liquid storage tank, and a reflux device; an atomization and splitting co-operating nozzle connected below the upper liquid storage tank, comprising a high-voltage electrostatic atomization system and a high-voltage gas device; a high-voltage electrostatic loading power supply used to form an upper high-voltage electrostatic loading layer on the nozzle of the high-voltage electrostatic atomization system and a lower high-voltage electrostatic loading layer above the surface of the lower liquid storage tank, thereby creating an electrostatic field region between the upper and lower loading layers for fiber bundle passage; and a fiber transmission and post-processing system comprising an unwinding and feeding device, a bundling device, and a winding device arranged sequentially along the fiber travel direction. This invention effectively avoids fiber fuzzing and breakage during the splitting process, significantly reduces fiber damage, and fundamentally improves the uniformity of sizing agent coverage and its bonding performance with the fiber.

Description

Technical Field

[0001] This invention relates to the field of fiber composite material preparation technology, specifically to a continuous directional fiber sizing device and method based on airflow splitting-electrostatic spray coupling. Background Technology

[0002] In the preparation of fiber-reinforced composite materials (such as carbon fiber, glass fiber, aramid fiber, etc.), sizing is a crucial step. The sizing agent acts as a "bridge" between the fiber and the matrix resin, effectively improving the wettability of the fiber and resin, increasing the interfacial bonding strength, reducing fuzz formation, and protecting the fiber surface from damage, thereby ultimately improving the mechanical properties of the composite material.

[0003] Traditional fiber sizing methods primarily employ the impregnation tank method, where fiber bundles are passed through a sizing tank filled with sizing agent, and the amount of sizing is controlled by a squeezing roller. This method has several inherent drawbacks: 1. Uneven sizing: The fiber bundles are densely packed, making it difficult to ensure that each monofilament is fully and evenly coated with sizing agent during impregnation, easily resulting in "dry filaments." 2. Low precision in sizing amount control: Relying on the pressure adjustment of the squeezing roller results in coarse control, easily causing fluctuations in sizing amount or wasting sizing agent. 3. Fiber damage: Repeated bending and friction of the fiber bundle between the sizing tank and the roller easily causes scratches or fuzz on the fiber surface. 4. Inability to directionally control: The sizing agent is randomly distributed on the fiber surface, making it difficult to achieve directional and selective deposition of the sizing agent according to interfacial performance requirements.

[0004] Airflow splitting technology can achieve non-contact splitting of fiber bundles, thus providing a fully uniform sizing environment for the sizing agent. However, it still faces some problems and challenges:

[0005] Fiber damage risk: namely, fuzzing and filament breakage. This is the core contradiction and the area that needs the most optimization in airflow splitting. Although it is non-contact, if the parameters are not appropriate, the damage is still serious, which limits the use of the technology. Currently, there are two main reasons: (1) Negative impact of airflow shear force: High-speed airflow is essentially applying a shear force to the fiber. If the airflow speed is too high or the point of application is too concentrated, this force may exceed the strength limit of a single fiber, causing the fiber to be blown off directly. (2) Severe friction between filaments: Ideally, splitting should allow the fiber bundle to unfold gently, but the blown filaments will beat and rub against each other at a very high speed, and rub against the parts, causing the fiber surface to easily produce fuzz or even abrasion. This is especially dangerous for brittle fibers (such as carbon fiber). Airflow splitting is mostly carried out on unsized fibers, which are not protected by sizing agents, are more brittle, and are more susceptible to wear and bending, resulting in fuzzing and filament breakage. Summary of the Invention

[0006] In view of this, embodiments of this application provide a continuous directional fiber sizing device and method based on airflow splitting-electrostatic spray coupling, so as to effectively improve the sizing uniformity and fiber bonding strength, effectively protect the fiber, and significantly reduce fiber damage.

[0007] This application provides the following technical solution: a continuous directional fiber sizing device based on airflow splitting-electrostatic spray coupling, comprising:

[0008] Liquid storage circulation system: includes an upper liquid storage tank, a lower liquid storage tank, and a reflux device connecting the upper liquid storage tank and the lower liquid storage tank;

[0009] Atomizing and filament splitting co-operated nozzle: connected below the upper liquid storage tank; the atomizing and filament splitting co-operated nozzle includes a high-voltage electrostatic atomizing system and a high-voltage gas device sleeved on the outside of the high-voltage electrostatic atomizing system. The high-voltage electrostatic atomizing system and the high-voltage gas device form a concentric double-layer tube structure, wherein the outlet channel of the high-voltage gas device is longer than the outlet of the high-voltage electrostatic atomizing system.

[0010] High-voltage electrostatic loading power supply: operates above the nozzle of the high-voltage electrostatic atomization system and the lower liquid storage tank, used to apply charge to the nozzle of the high-voltage electrostatic atomization system to form an upper high-voltage electrostatic loading layer, so that the atomized sizing agent droplets are charged, and to apply charge with opposite polarity to the upper high-voltage electrostatic loading layer above the recovery surface of the lower liquid storage tank to form a lower high-voltage electrostatic loading layer; an electrostatic field region for fiber bundles to pass through is formed between the upper high-voltage electrostatic loading layer and the lower high-voltage electrostatic loading layer;

[0011] Fiber transmission and post-processing system: includes an unwinding and feeding device, a bundling device, and a winding device arranged sequentially along the fiber travel direction. The unwinding and feeding device is used to continuously transport the fiber bundle to perform fiber transmission and feeding in the electrostatic field region formed between the upper high-voltage electrostatic loading layer and the lower high-voltage electrostatic loading layer. The bundling device is arranged on the fiber bundle travel path and is used to re-bundle the sized and modified filaments. The winding device is used to dry and wind up the sized and bundled fiber bundle.

[0012] According to one embodiment of this application, a negative pressure recovery system is also included, the negative pressure recovery system comprising a vacuum pump and a filter, the vacuum pump being used to generate negative pressure in the lower liquid storage tank to transport the sizing agent back to the upper liquid storage tank through the reflux device, forming a sizing agent circulation loop; the filter being used to filter fibers and impurities in the liquid flowing from the lower high-voltage electrostatic loading layer into the lower liquid storage tank.

[0013] According to one embodiment of this application, an insulating layer is further included, the insulating layer being disposed between the lower high-voltage electrostatic loading layer and the lower liquid storage tank.

[0014] According to one embodiment of this application, the lower high-voltage electrostatic loading layer is provided with a plurality of filter holes penetrating the recovery surface of the lower liquid storage tank.

[0015] According to one embodiment of this application, the diameter of the sizing agent droplets generated by the high-voltage electrostatic atomization system ranges from 10 nanometers to 100 micrometers.

[0016] According to one embodiment of this application, the drying method of the winding device is hot air drying, infrared drying, or microwave drying.

[0017] According to one embodiment of this application, the fiber is carbon fiber, glass fiber, quartz fiber, silicon carbide fiber, polyester fiber, polylactic acid fiber, cotton fiber, or linen fiber.

[0018] This application also provides a continuous directional fiber sizing method using the equipment described above, comprising the following steps:

[0019] S1. Fiber bundle conveying: The fiber bundle is continuously conveyed by the unwinding and feeding device so that the fiber bundle passes through the electric field region formed between the upper high voltage electrostatic loading layer and the lower high voltage electrostatic loading layer.

[0020] S2, Cooperative fiber splitting and atomization: The high-speed airflow ejected by the high-pressure gas device splits the fiber bundle into fibers, and at the same time, the high-pressure electrostatic atomization system atomizes the sizing agent into charged sizing agent droplets, so that the charged sizing agent droplets are carried and guided by the high-speed airflow to the split fibers;

[0021] S3, Directional electrostatic deposition: The upper high-voltage electrostatic loading layer and the lower high-voltage electrostatic loading layer are controlled to carry charges of different polarities through the high-voltage electrostatic loading power supply, so that charged sizing agent droplets with the same charge polarity as the upper high-voltage electrostatic loading layer are directionally deposited on the surface of the monofilament fiber under the combined action of the high-speed airflow and the electrostatic field.

[0022] S4. Sizing agent recovery and recycling: Through the negative pressure recovery system, the undeposited sizing agent is drawn into the lower storage tank through the filter holes of the lower high voltage electrostatic loading layer, and after filtration, it is pumped back to the upper storage tank for recycling.

[0023] S5. Bundling and Drying: The sized fibers are re-bundled, dried, and then wound up.

[0024] According to one embodiment of this application, in step S3, the degree of fiber splitting and the uniformity of sizing agent deposition are controlled in a coordinated manner by adjusting the airflow speed of the high-pressure gas device and the voltage of the high-pressure electrostatic loading power supply.

[0025] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least:

[0026] (1) Extremely high uniformity of sizing and fiber bonding strength: It achieves precise sizing at the monofilament level, completely eliminating the phenomenon of uneven fiber sizing concentration or even no sizing inside. The sizing agent bonds to the fiber surface through electrostatic attraction, with strong and uniform bonding force, which greatly improves the bonding performance between the fiber and the sizing agent.

[0027] (2) Effectively protects fibers and significantly reduces damage: By using the "splitting-sizing" synchronous strategy, the sizing agent deposited in real time is used as a "protective layer", which fundamentally overcomes the technical problem that single airflow splitting technology is prone to fiber fuzzing and breakage, and is especially suitable for brittle high-performance fibers.

[0028] (3) The sizing process is precise and controllable: By adjusting the airflow parameters (speed, angle) and electrostatic parameters (voltage), the degree of fiber splitting, the amount and distribution of sizing agent deposition can be precisely controlled, realizing the digital and programmable control of the sizing process.

[0029] (4) High utilization rate of sizing agent, economical and environmentally friendly: The closed negative pressure recovery system significantly reduces the waste and volatilization of sizing agent, and reduces production costs and environmental impact.

[0030] (5) Great potential for functional expansion: This technology provides a precise and universal platform for advanced functional modification such as directional modification of nanoparticles on fiber surface and construction of multi-layer structure, and can easily endow composite materials with other properties in addition to mechanical properties (such as electrical conductivity, thermal conductivity, etc.).

[0031] This invention, through the innovative coupling of airflow splitting and electrostatic spraying, not only comprehensively solves the respective defects of traditional methods, but also produces a good synergistic effect, providing a revolutionary fiber sizing solution for the preparation of high-performance composite materials. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of a continuous directional fiber sizing device based on airflow splitting-electrostatic spray coupling provided in an embodiment of the present invention;

[0034] Figure 2This is a schematic diagram of the electrostatic atomization system in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram illustrating the working principle of airflow disturbance-coordinated sizing in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the lower liquid storage tank and the high-voltage electrostatic loading layer in an embodiment of the present invention;

[0037] Among them, 1-upper liquid storage tank, 2-high voltage electrostatic atomization system, 3-high voltage gas device, 4-upper high voltage electrostatic loading layer, 5-lower high voltage electrostatic loading layer, 6-lower liquid storage tank, 7-high voltage electrostatic loading power supply, 8-reflux device, 9-insulation layer, 10-filter holes, 11-negative pressure recovery system. Detailed Implementation

[0038] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0039] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] like Figures 1-4 As shown, this embodiment of the invention provides a continuous directional fiber sizing device based on airflow splitting-electrostatic spray coupling, comprising:

[0041] Liquid storage circulation system: includes an upper liquid storage tank 1, a lower liquid storage tank 6, and a reflux device 8 connecting the upper liquid storage tank 1 and the lower liquid storage tank 6;

[0042] Atomizing and filament splitting co-operated nozzle: connected below the upper liquid storage tank 1; the atomizing and filament splitting co-operated nozzle includes a high-voltage electrostatic atomizing system 2 and a high-voltage gas device 3 sleeved on the outside of the high-voltage electrostatic atomizing system 2. The high-voltage electrostatic atomizing system 2 and the high-voltage gas device 3 form a concentric double-layer tube structure, wherein the outlet channel of the high-voltage gas device 3 is longer than the outlet of the high-voltage electrostatic atomizing system 2;

[0043] High-voltage electrostatic loading power supply 7: operates above the nozzle of the high-voltage electrostatic atomization system 2 and the lower liquid storage tank 6, for applying charge to the nozzle of the high-voltage electrostatic atomization system 2 to form an upper high-voltage electrostatic loading layer 4, so that the atomized sizing agent droplets are charged, and for applying charge with opposite polarity to the upper high-voltage electrostatic loading layer 4 above the recovery surface of the lower liquid storage tank 6 to form a lower high-voltage electrostatic loading layer 5; an electrostatic field region for fiber bundles to pass through is formed between the upper high-voltage electrostatic loading layer 4 and the lower high-voltage electrostatic loading layer 5; the lower high-voltage electrostatic loading layer 5 is provided with multiple filter holes 10 penetrating the recovery surface of the lower liquid storage tank 6;

[0044] Insulating layer 9: The insulating layer 9 is disposed between the lower high-voltage electrostatic loading layer 5 and the lower liquid storage tank 6;

[0045] The negative pressure recovery system 11 includes a vacuum pump and a filter. The vacuum pump is used to generate negative pressure in the lower liquid storage tank 6 to transport the sizing agent back to the upper liquid storage tank 1 through the return device 8, forming a sizing agent circulation loop. The filter is used to filter out fibers and impurities in the liquid flowing into the lower liquid storage tank 6 from the lower high-voltage electrostatic loading layer 5.

[0046] Fiber transmission and post-processing system: includes an unwinding and feeding device, a bundling device, and a winding device arranged sequentially along the fiber travel direction. The unwinding and feeding device is used to continuously transport the fiber bundle to perform fiber transmission and feeding in the electrostatic field region formed between the upper high-voltage electrostatic loading layer 4 and the lower high-voltage electrostatic loading layer 5. The bundling device is arranged on the fiber bundle travel path and is used to re-bundle the sized and modified filaments. The winding device is used to dry and wind up the sized and bundled fiber bundle.

[0047] This invention proposes a continuous directional fiber sizing device based on airflow splitting-electrostatic spray coupling, aiming to solve the inherent defects of existing fiber sizing technologies, especially the traditional impregnation method and the single airflow splitting method. These problems mainly include: 1. Traditional impregnation method: uneven sizing, differences in sizing concentration between fiber bundles, low precision in sizing amount control, easy fiber damage caused by mechanical contact operation, and inability to achieve directional deposition of sizing agent. 2. Single airflow splitting method: during the splitting process, the shear force exerted by the high-speed airflow on the unprotected fragile fibers (such as carbon fibers) and the resulting severe friction between monofilaments can easily lead to fiber fuzzing and breakage, limiting the application effect and reliability of this technology.

[0048] This invention creatively "couples" two technical modules from different technical fields that solve different problems into one system to synergistically solve the deep pain points in the specific field of fiber composite sizing. The key to this invention lies in the synergistic effect generated by the "coupling": (1) Airflow splitting creates the premise for electrostatic spraying: only when the fiber bundle is fully and gently separated to expose the individual filaments can the "precise deposition" of electrostatic spraying be meaningful. Otherwise, the atomized slurry can only adhere to the surface of the fiber bundle, which solves the problem of uniformity of sizing; in addition, the airflow of the airflow splitting can also provide a directional deposition force for the atomized charged droplets, realizing precise directional and controllable deposition in the sizing process, solving the sizing pain points of existing traditional sizing agents; (2) Electrostatic spraying utilizes the conditions created by splitting: and uses electrostatic attraction to precisely "pull" the slurry to each exposed monofilament, realizing molecular-level bonding, fundamentally solving the problem of poor bonding. In addition, during the splitting process, sizing the fiber can provide real-time protection for the fiber, reduce friction between fibers and with components, and improve fiber toughness by forming a slurry film on the fiber surface, reducing fuzzing and fiber breakage, solving the pain points of existing pneumatic splitting. This integrated design concept of "physical splitting plus electrostatic directional adsorption synergistic sizing" can "completely avoid" the individual limitations of each traditional method.

[0049] In some embodiments of the present invention, the diameter of the sizing agent droplets generated by the high-voltage electrostatic atomization system 2 ranges from 10 nanometers to 100 micrometers.

[0050] In specific implementation, the continuous directional fiber sizing equipment based on airflow splitting-electrostatic spray coupling in this embodiment specifically includes:

[0051] 1. A liquid storage system, including an upper liquid storage tank 1 for storing sizing agent, a lower liquid storage tank 6 for storing used sizing agent, and a reflux device 8 (including pipelines, filters and vacuum pump) connecting the upper and lower liquid storage tanks 6. This structure system can realize the collection, recovery, filtration, purification and recycling of sizing agent, forming an efficient sizing agent circulation system and reducing the waste of sizing agent.

[0052] 2. A high-voltage electrostatic atomization system 2, connected below the upper liquid storage tank 1, is used to receive the sizing agent. Under the action of a high-voltage electric field, the surface tension of the liquid is overcome by high-voltage electrostatic force, thereby breaking the sizing agent liquid into extremely small and uniform charged droplets. The high-voltage electrostatic atomization system 2 generates sizing agent droplets with a concentrated particle size distribution in the nanometer to micrometer range, which can ensure that the sizing agent can penetrate smoothly into the fiber bundle and ensure that the sizing agent is evenly distributed on the surface of a single fiber, so that the fiber bundle is sized uniformly. The sizing agent droplets are charged, which can further achieve directional movement under the electric field conditions, and also provide the basic conditions for their precise deposition and firm bonding on the fiber surface.

[0053] 3. The high-pressure gas device 3 and the electrostatic atomization system are concentric double-layer tube structures. The high-pressure gas device 3 is longer than the electrostatic atomization system to ensure stable airflow of charged droplets at the outlet. There is a certain distance between the two tubes to allow the high-speed airflow generated by the high-pressure gas device 3 to pass through. The concentric double-layer tube structure enables the airflow splitting and electrostatic spraying to work synergistically in space, ensuring that the atomized charged sizing agent droplets can enter the electrostatic spraying area in a controllable and orderly manner through the high-pressure gas to modify the fibers.

[0054] The high-voltage electrostatic charging power supply 7 applies charge to the nozzle of the electrostatic atomization system to atomize the sizing agent and charge the atomized sizing agent droplets. This area is designated as the upper high-voltage electrostatic charging layer 4, located below the upper liquid storage tank 1 and above the fiber bundle travel path. The high-voltage electrostatic charging power supply 7 applies a different charge to the lower high-voltage electrostatic charging layer 5, which is provided with multiple filter holes 10 penetrating its upper and lower surfaces. These are primarily used to receive the charged sizing agent and recover it through the filter holes 10.

[0055] 4. The high-voltage electrostatic loading power supply 7 is used to generate an opposite charge on the fiber surface to the charge carried by the sizing agent droplets in the upper electrostatic loading layer. This can attract the charged sizing agent droplets and cause them to be deposited directionally onto the surface of the split fiber. Through electrostatic adsorption, the sizing agent is uniformly and firmly attached to the fiber surface, which significantly improves the bonding performance between the fiber and the sizing agent and completes the directional sizing modification.

[0056] 5. An insulating layer 9 is disposed below the high-voltage electrostatic loading layer. The insulating layer 9 is made of a highly insulating material that is resistant to chemical corrosion, ensuring electrical isolation between the high-voltage electrostatic loading layer and the lower liquid storage tank 6 and other grounded components of the equipment. The insulating material is made of polytetrafluoroethylene, rubber, ceramic and other insulating materials, which have excellent chemical corrosion resistance and high insulation performance, adapt to the working environment of various sizing agents, and ensure the stability of the high-voltage electrostatic field and operational safety.

[0057] 6. The lower storage tank 6 is located below the insulating layer 9, and a vacuum pump is used to create negative pressure inside to collect the sizing agent.

[0058] 7. A vacuum filtration device (the aforementioned negative pressure recovery system 11) includes a vacuum pump and a filter. The vacuum pump is connected to the upper storage tank 1 and the lower storage tank 6 via a pipeline. The vacuum pump generates negative pressure in the lower storage tank 6, which transports the sizing agent back to the upper storage tank 1 through the return device 8, forming a sizing agent circulation loop and achieving efficient recycling of the sizing agent. The filter is used to filter impurities in the liquid flowing from the upper storage tank 1 into the lower storage tank 6 through the filter holes 10 of the high-voltage electrostatic loading layer.

[0059] 8. The filter is installed on the pipeline between the vacuum pump and the lower liquid storage tank 6, or inside the lower liquid storage tank 6, for filtering fibers and other impurities in the liquid flowing into the lower liquid storage tank 6 from the high-voltage electrostatic loading layer. The multi-layer filtration design of the filter can effectively remove impurities of different particle sizes, ensuring the quality of the recovered sizing agent. The adjustable flow design of the reflux device 8 makes the recovery and reuse process of the sizing agent more precise and controllable.

[0060] 9. A fiber feeding device, including an unwinding device and a winding device, for continuously conveying fiber bundles and feeding fibers in the intermediate area formed by the lower high-voltage electrostatic loading layer 5 and the upper high-voltage electrostatic loading layer 4.

[0061] 10. A bundling device, disposed on the fiber bundle travel path and located in front of the drying and winding section, is used to re-bundle the sized and modified filaments.

[0062] 11. The winding device includes a drying function for drying the fiber bundles that have been sized and bundled, thereby achieving continuous and integrated sizing process and improving production efficiency.

[0063] 12. The reflux device 8 is connected between the lower storage tank 6 and the upper storage tank 1. It is used to pump the filtered sizing agent back to the upper storage tank 1 to form a closed circulation system, which significantly improves the utilization rate of the sizing agent and the economic efficiency of the process.

[0064] The high-voltage electrostatic loading power supply 7 includes, but is not limited to, a DC high-voltage power supply or a pulse high-voltage power supply, providing a flexible and adjustable electrostatic loading mode. It can automatically adjust the output voltage and frequency according to different sizing agent properties and process requirements to adapt to the process requirements of different fibers and sizing agents.

[0065] The drying function of the winding device includes, but is not limited to, using hot air drying, infrared drying or microwave drying methods, providing a variety of drying options to ensure that the sizing agent quickly forms a film and a stable sizing layer.

[0066] The fibers mentioned include, but are not limited to, carbon fiber, glass fiber, quartz fiber, silicon carbide fiber, polyester fiber, polylactic acid fiber, cotton fiber, and linen fiber.

[0067] like Figure 1 As shown, the fiber moves during the unwinding and winding process. The fiber is unwound by the unwinding device assembly, and wound and dried by the winding device. The sizing surface of the fiber is achieved through path planning. Figure 2As shown, the sizing agent is stored in the upper storage tank 1 and flows into the high-voltage electrostatic atomization system 2. The high-voltage electrostatic atomization system 2 disperses the sizing agent into small droplets (10 nm-100 µm in diameter) using a high-voltage electric field. These small droplets then apply directional sizing to the fiber surface using a high-voltage carrier gas. Figure 3 As shown, the high-pressure gas device 3 agitates and separates the fiber bundle using airflow, and carries atomized sizing agent droplets to sizing and modify the separated fibers. After sizing and modification, the fibers are re-bundled using a bundling device. Furthermore, a high-voltage electrostatic device charges the fibers with an opposite charge to the sizing agent droplets, increasing the interaction force between the droplets and the fibers. (This step is performed if the fibers are conductive, such as carbon fiber; it is not used if they are not charged, such as glass fiber.)

[0068] The core of the continuous directional fiber sizing equipment of the present invention lies in creating an integrated and synergistic solution for physical fiber separation, directional sizing, electrostatic deposition, real-time protection, and recycling. The equipment mainly includes a liquid storage system, a high-voltage electrostatic atomization system 2, a high-voltage gas device 3, a deposition zone with upper and lower high-voltage electrostatic loading layers 5, an insulation layer 9, a lower liquid storage tank 6, a vacuum filtration and recovery device, a transmission and fiber feeding device, and a bundle drying device.

[0069] Its core lies in the technical coupling of airflow splitting and electrostatic spraying:

[0070] Collaborative Process: First, a controllable high-speed airflow generated by a high-pressure gas device 3 non-contactly agitates the continuously moving fiber bundle, achieving monofilament-level dispersion and creating conditions for uniform sizing. Almost simultaneously, a high-pressure electrostatic atomization system 2 atomizes the sizing agent into charged micron / nano-sized droplets. This droplet cluster is precisely carried and guided by the same high-speed airflow to the separated fiber region.

[0071] Directional deposition mechanism: A high-voltage electrostatic power supply 7 applies a charge opposite to that of the droplets to the surfaces of the upper and lower high-voltage electrostatic loading layers 5, causing the exposed fiber monofilament surfaces to acquire the target charge. Under the combined action of airflow dynamics and electrostatic attraction, the charged droplets are rapidly and precisely adsorbed and firmly deposited on the surface of each fiber.

[0072] Real-time protection mechanism: The key advantage of this coupling process is that the deposition of the sizing agent and the fiber separation process are carried out simultaneously. The newly separated, highly vulnerable fiber monofilaments are immediately coated with sizing agent droplets, forming a protective film, which significantly reduces fuzzing and breakage caused by airflow disturbance and monofilament friction.

[0073] Recycling system: The excess sizing agent that fails to settle is recovered to the lower storage tank 6 through the filter holes 10 of the lower high-voltage electrostatic loading layer 5 via a negative pressure suction system. After filtration and purification, it is pumped back into the system for recycling, achieving high economy and environmental protection.

[0074] This invention employs a continuous directional fiber sizing method using the equipment described above, comprising the following steps:

[0075] S1. Fiber bundle conveying: The fiber bundle is continuously conveyed by the unwinding and feeding device so that the fiber bundle passes through the electric field region formed between the upper high voltage electrostatic loading layer 4 and the lower high voltage electrostatic loading layer 5.

[0076] S2, Cooperative fiber splitting and atomization: The high-speed airflow ejected by the high-pressure gas device 3 splits the fiber bundle into fibers, while the high-pressure electrostatic atomization system 2 atomizes the sizing agent into charged sizing agent droplets, so that the charged sizing agent droplets are carried and guided by the high-speed airflow to the split fibers;

[0077] S3, Directional electrostatic deposition: The high-voltage electrostatic loading power supply 7 controls the upper high-voltage electrostatic loading layer 4 and the lower high-voltage electrostatic loading layer 5 to carry charges of different polarities, so that charged sizing agent droplets with the same charge polarity as the upper high-voltage electrostatic loading layer 4 are directionally deposited on the surface of the monofilament fiber under the combined action of the high-speed airflow and the electrostatic field.

[0078] In step S3, the degree of fiber splitting and the uniformity of sizing agent deposition are controlled in synergy by adjusting the airflow speed of the high-pressure gas device 3 and the voltage of the high-pressure electrostatic loading power supply 7.

[0079] S4. Sizing agent recovery and recycling: The undeposited sizing agent is drawn into the lower storage tank 6 through the filter holes 10 of the lower high voltage electrostatic loading layer 5 via the negative pressure recovery system 11, and then pumped back to the upper storage tank 1 for recycling after filtration.

[0080] S5. Bundling and Drying: The sized fibers are re-bundled, dried, and then wound up.

[0081] In specific implementation, the continuous directional fiber sizing method of this embodiment achieves synergistic regulation of the high degree of fiber splitting and the directional, rapid, and efficient deposition of the sizing agent by precisely controlling the matching relationship between the airflow velocity and the electrostatic field; by optimizing the negative pressure recovery parameters, the sizing agent is efficiently recovered and reused while ensuring the sizing effect. The method includes the following steps:

[0082] 1. Fiber bundle conveying: The fiber bundle is continuously conveyed from the unwinding and feeding device to the intermediate area formed by the upper high-voltage electrostatic loading layer 4 and the lower high-voltage electrostatic loading layer 5 through the transmission feeding device. The conveying speed is controlled by the transmission motor and the transmission rate is adjusted according to different fibers and sizing requirements. The sizing surface of the fiber is achieved through path planning.

[0083] 2. Airflow splitting: High-speed airflow is injected into the fiber bundle in the middle region through a high-pressure gas device 3. The airflow speed varies according to the fiber rate, disturbing and dispersing the tightly packed fiber bundle to achieve single-filament splitting, allowing the fiber bundle to fully unfold and creating the necessary conditions for uniform sizing. In addition, the high-speed airflow is oriented through the concentric double-layer tube structure of the nozzle, which can precisely and efficiently control the direction and speed of the charged droplets of the sizing agent, so that the sizing agent is applied only to the fiber area, thereby achieving a precise and efficient sizing effect.

[0084] 3. Electrostatic atomization and charge loading: The sizing agent from the upper liquid storage tank 1 is atomized into charged micro-droplets by the high-voltage electrostatic atomization system 2; at the same time, the high-voltage electrostatic loading power supply 7 loads the upper high-voltage electrostatic loading layer 4 and the lower high-voltage electrostatic loading layer 5 with a charge opposite to that of the atomized droplets, providing a basis for the subsequent directional movement of droplets in the electric field and deposition on the surface of charged fibers.

[0085] 4. Directional Deposition Sizing: The high-speed airflow generated by the high-pressure gas device 3 carries the charged sizing agent droplets and the electric field formed between the high-voltage electrostatic loading power supply 7 and the high-voltage electrostatic loading layer. This dual action causes the sizing agent droplets to move in a directional manner. Simultaneously, the fiber bundle, due to the action of the high-voltage electrostatic loading layer, carries a charge opposite to that of the charged sizing agent droplets on its surface. Through electrostatic attraction, the charged sizing agent droplets are rapidly, efficiently, accurately, and uniformly deposited onto the surface of the split monofilament fibers. The directional, uniform, and firm adhesion of the sizing agent to the fiber surface provides excellent protection, reduces fiber breakage and fuzzing, and significantly improves the bonding strength between the fiber and the sizing agent. Furthermore, the directional and precise adhesion of the sizing agent to the fiber surface enables the refined structural construction of the fiber interface layer, which helps improve the interfacial properties of the composite material and endows it with multifunctionality.

[0086] If the fiber is an insulating fiber, the sizing agent droplets are directionally deposited mainly by the high-speed airflow generated by the high-pressure gas device 3. This allows the charged sizing agent droplets to be deposited quickly, efficiently, accurately, and uniformly onto the surface of the split monofilament fiber. This achieves directional, uniform, and firm adhesion of the sizing agent to the fiber surface, providing good protection for the fiber surface, reducing phenomena such as fiber breakage and fuzzing, and significantly improving the bonding strength between the fiber and the sizing agent.

[0087] 5. Negative Pressure Recovery and Sizing Material Circulation: A vacuum pump generates negative pressure in the lower storage tank 6, causing excess sizing agent droplets that fail to deposit effectively on the fiber surface, as well as dripping or splashing sizing agent, to be drawn into the lower storage tank 6 through the filter holes 10 of the lower high-voltage electrostatic loading layer 5. After filtering out fiber filaments and impurities, the clean sizing agent is pumped back to the upper storage tank 1 through the reflux device 8, establishing an efficient sizing material recovery and circulation system, significantly reducing sizing agent consumption, improving process economy and environmental protection, and realizing the recycling of sizing agent.

[0088] 6. Bundling and Drying: The sized and modified filaments are re-bundled into fiber bundles using a bundling device, and then dried and wound up using a winding device.

[0089] In step 3, the diameter of the sizing agent droplets generated by the high-voltage electrostatic atomization system 2 ranges from 10 nanometers to 100 micrometers. By controlling the droplet size, fine sizing from the nanometer to the micrometer level is achieved, optimizing the sizing effect on the fiber surface and realizing uniform and rapid sizing of the fiber surface.

[0090] In step 5, the negative pressure recovery and sizing circulation can ensure the effective recovery of excess sizing agent without interfering with the directional deposition process of charged droplets on the fiber surface in step 4. It precisely balances the deposition and recovery process, ensuring sizing effect and recovery efficiency.

[0091] In step 6, the drying method includes, but is not limited to, hot air drying, infrared drying or microwave drying. The optimal drying method is selected according to the characteristics of different sizing agents to ensure that the sizing agent is fully cured without damaging the fiber.

[0092] This invention couples airflow splitting with electrostatic spraying technology. Non-contact airflow achieves monofilament-level dispersion of fiber bundles, while a high-voltage electrostatic field atomizes the sizing agent into charged microdroplets. These charged microdroplets, guided by airflow and driven by the electric field, rapidly and precisely deposit on the fiber surface, achieving directional, rapid, uniform, and robust coating of the sizing agent simultaneously with splitting. This synergistic effect effectively avoids fiber fuzzing and breakage during splitting, significantly reduces fiber damage, and fundamentally improves the uniformity of sizing agent coverage and its bonding performance with the fiber. This invention also integrates a sizing agent recycling system, enabling efficient filtration and recycling of excess sizing material. This invention overcomes the limitations of existing sizing technologies in terms of control precision, sizing speed, fiber protection, and directional sizing.

[0093] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A continuous directional fiber sizing device based on airflow splitting-electrostatic spray coupling, characterized in that, include: Liquid storage circulation system: includes an upper liquid storage tank, a lower liquid storage tank, and a reflux device connecting the upper liquid storage tank and the lower liquid storage tank; Atomizing and filament splitting co-operated nozzle: connected below the upper liquid storage tank; the atomizing and filament splitting co-operated nozzle includes a high-voltage electrostatic atomizing system and a high-voltage gas device sleeved on the outside of the high-voltage electrostatic atomizing system. The high-voltage electrostatic atomizing system and the high-voltage gas device form a concentric double-layer tube structure, wherein the outlet channel of the high-voltage gas device is longer than the outlet of the high-voltage electrostatic atomizing system. High-voltage electrostatic loading power supply: operates above the nozzle of the high-voltage electrostatic atomization system and the lower liquid storage tank, used to apply charge to the nozzle of the high-voltage electrostatic atomization system to form an upper high-voltage electrostatic loading layer, so that the atomized sizing agent droplets are charged, and to apply charge with opposite polarity to the upper high-voltage electrostatic loading layer above the recovery surface of the lower liquid storage tank to form a lower high-voltage electrostatic loading layer; an electrostatic field region for fiber bundles to pass through is formed between the upper high-voltage electrostatic loading layer and the lower high-voltage electrostatic loading layer; Fiber transmission and post-processing system: includes an unwinding and feeding device, a bundling device, and a winding device arranged sequentially along the fiber travel direction. The unwinding and feeding device is used to continuously transport the fiber bundle to perform fiber transmission and feeding in the electrostatic field region formed between the upper high-voltage electrostatic loading layer and the lower high-voltage electrostatic loading layer. The bundling device is arranged on the fiber bundle travel path and is used to re-bundle the sized and modified filaments. The winding device is used to dry and wind up the sized and bundled fiber bundle. It also includes a negative pressure recovery system, which includes a vacuum pump and a filter. The vacuum pump is used to generate negative pressure in the lower liquid storage tank to transport the sizing agent back to the upper liquid storage tank through the reflux device, forming a sizing agent circulation loop. The filter is used to filter out fibers and impurities in the liquid flowing from the lower high-voltage electrostatic loading layer into the lower liquid storage tank. The continuous directional fiber sizing method of the equipment includes the following steps: S1. Fiber bundle conveying: The fiber bundle is continuously conveyed by the unwinding and feeding device so that the fiber bundle passes through the electric field region formed between the upper high voltage electrostatic loading layer and the lower high voltage electrostatic loading layer. S2, Cooperative fiber splitting and atomization: The high-speed airflow ejected by the high-pressure gas device splits the fiber bundle into fibers, and at the same time, the high-pressure electrostatic atomization system atomizes the sizing agent into charged sizing agent droplets, so that the charged sizing agent droplets are carried and guided by the high-speed airflow to the split fibers; S3, Directional electrostatic deposition: The upper high-voltage electrostatic loading layer and the lower high-voltage electrostatic loading layer are controlled to carry charges of different polarities through the high-voltage electrostatic loading power supply, so that charged sizing agent droplets with the same charge polarity as the upper high-voltage electrostatic loading layer are directionally deposited on the surface of the monofilament fiber under the combined action of the high-speed airflow and the electrostatic field. In step S3, the degree of fiber splitting and the uniformity of sizing agent deposition are controlled in synergistically by adjusting the airflow speed of the high-pressure gas device and the voltage of the high-pressure electrostatic loading power supply. S4. Sizing agent recovery and recycling: Through the negative pressure recovery system, the undeposited sizing agent is drawn into the lower storage tank through the filter holes of the lower high voltage electrostatic loading layer, and after filtration, it is pumped back to the upper storage tank for recycling. S5. Bundling and Drying: The sized fibers are re-bundled, dried, and then wound up.

2. The continuous directional fiber sizing equipment according to claim 1, characterized in that, It also includes an insulating layer disposed between the lower high-voltage electrostatic loading layer and the lower liquid storage tank.

3. The continuous directional fiber sizing equipment according to claim 1, characterized in that, The lower high-voltage electrostatic loading layer is provided with multiple filter holes that penetrate the recovery surface of the lower liquid storage tank.

4. The continuous directional fiber sizing equipment according to claim 1, characterized in that, The diameter of the sizing agent droplets generated by the high-voltage electrostatic atomization system ranges from 10 nanometers to 100 micrometers.

5. The continuous directional fiber sizing equipment according to claim 1, characterized in that, The drying method of the winding device is hot air drying, infrared drying, or microwave drying.

6. The continuous directional fiber sizing equipment according to claim 1, characterized in that, The fibers are carbon fiber, glass fiber, quartz fiber, silicon carbide fiber, polyester fiber, polylactic acid fiber, cotton fiber, or linen fiber.

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