Twin-screw unit for dispersing carbon nanotube conductive slurry

Abstract

The utility model discloses a double-screw unit for dispersing conductive paste of a carbon nano tube. The unit comprises a rack box, a base, a main motor, an auxiliary motor, a main transmission box, an auxiliary transmission box, a main screw box, an auxiliary screw box and double screws which are meshed and rotated in the same direction and are arranged in a barrel. The cylinder body is fixed on the rack box and is provided with a feeding hole and a discharging hole; the two screw shafts are driven by a main motor, a main coupler, a main transmission case, a main screw case, an auxiliary motor, an auxiliary coupler, an auxiliary transmission case and an auxiliary screw case respectively. The core innovation is that the length-diameter ratio L / D of the effective working part of the double screws is 68-76; the barrel is composed of sixteen sections of standard length units and is divided into a shearing section, a dispersing section, a homogenizing section and a conveying section in the material flowing direction, and each section is provided with four sections of barrel units; the feeding port is formed in the shearing section, and the discharging port is formed in the conveying section. The unit realizes efficient, uniform and continuous dispersion of carbon nanotube conductive paste through high length-diameter ratio, fine functional section division and dual-motor driving.

Description

Technical Field

[0001] The utility model relates to the technical field of carbon nanotube conductive slurry preparation equipment, and more specifically, to a twin-screw extruder unit for dispersing carbon nanotube conductive slurry. Background Art

[0002] Carbon nanotubes (CNTs), due to their unique nanostructure and excellent mechanical, electrical, and thermal properties, hold great promise for applications in composite materials, conductive pastes, energy storage, sensors, and other fields. However, their extremely high surface area and strong van der Waals forces make them prone to agglomeration, making uniform and stable dispersion in matrix materials difficult. This has become a key bottleneck hindering their full performance and large-scale application.

[0003] Currently, methods for improving the dispersibility of carbon nanotubes mainly include mechanical stirring, high-shear mixing, ultrasonic dispersion, ball milling or sand milling, etc. These methods or combined processes have more or less some problems: for example, mechanical stirring and high-shear mixing have limited effect on breaking up tight carbon nanotube agglomerates; although ultrasonic dispersion has certain effects on a laboratory scale, it has high energy consumption and low efficiency in large-scale production, and may damage the structural integrity of carbon nanotubes; methods such as ball milling or sand milling that rely on grinding media (such as zirconia beads) have better dispersion effects, but there are problems such as impurities introduced into the grinding media, difficulty in separating the media from the product, severe equipment wear, high maintenance costs, and usually intermittent production, which makes it difficult to meet the needs of efficient, low-cost, and continuous production.

[0004] Therefore, how to provide a structurally optimized preparation device that can achieve efficient, uniform, and continuous dispersion of carbon nanotubes without the need for grinding media has become a technical challenge that urgently needs to be solved in this field. Utility Model Content

[0005] The purpose of the utility model is to provide a twin-screw extruder for dispersing carbon nanotube conductive slurry, aiming to solve the problems existing in the existing carbon nanotube dispersion process, such as dependence on grinding media, low dispersion efficiency, difficulty in continuous production, and possible damage to the carbon nanotube structure.

[0006] The utility model provides a twin-screw extruder unit for dispersing carbon nanotube conductive slurry, comprising a frame box, a base supporting the frame box, a main motor and an auxiliary motor arranged on opposite sides of the frame box, a main transmission box connected to the main motor and the auxiliary motor respectively, an auxiliary transmission box, a main screw box, an auxiliary screw box, and a twin screw arranged in a barrel; the barrel is fixed to the frame box, and the twin screw comprises two mutually meshing screw shafts, one of the screw shafts is driven by the main motor, the main coupling, the main transmission box, and the main screw box, which are sequentially connected, and the other screw shaft is driven by the auxiliary motor, the auxiliary coupling, the auxiliary transmission box, and the auxiliary screw box; the barrel is provided with a feed inlet and a discharge outlet;

[0007] The length-to-diameter ratio L / D of the effective working part of the twin screw is 68-76;

[0008] The cylinder is composed of sixteen cylinder units of standard length connected along the axial direction, and is divided into shearing section, dispersion section, homogenizing section and conveying section along the material flow direction; the shearing section, dispersion section, homogenizing section and conveying section are each composed of four cylinder units;

[0009] The feed port is arranged on the first section of the cylinder unit of the shearing section, and the discharge port is arranged on the last section of the cylinder unit of the conveying section.

[0010] Optionally, the outside of each cylinder section of the shearing section, the dispersion section, the homogenization section and the conveying section is provided with an independent cooling water inlet and cooling water outlet, and each cylinder section is provided with a temperature measuring port.

[0011] Optionally, each cylindrical unit of the shearing section, the dispersion section, the homogenizing section and the conveying section is provided with an independent cooling water inlet and cooling water outlet on the outside, and each cylindrical unit is provided with a temperature measuring port.

[0012] Optionally, the twin-screw unit also includes a control cabinet and a chiller; the control cabinet is electrically connected to each temperature measuring port for independently and accurately controlling the temperature of the shearing section, dispersion section, homogenization section and conveying section; the chiller is connected to each cooling water inlet and cooling water outlet through pipelines.

[0013] Optionally, the screw elements of the twin screws in the shearing section are configured to include a conveying screw element and a kneading block configured in cooperation with the conveying screw element.

[0014] Preferably, the screw elements in the shearing section are helical high-angle tooth elements and are equipped with a certain number of reverse thread elements.

[0015] Optionally, the screw elements of the twin-screw in the dispersion section are configured to include: multiple groups of kneading blocks of different thicknesses and different staggered angles, the kneading blocks being configured to exert a strong shearing effect on the material; and toothed disc mixing elements arranged in conjunction with the kneading blocks.

[0016] Preferably, the screw elements in the dispersion section are small-angle tooth elements and are equipped with a certain number of perforated plates.

[0017] Optionally, the screw elements of the twin-screw extruder in the homogenizing section are configured to include: a kneading block, the geometric parameters of which are configured to exert a shearing effect on the material to improve the uniformity of dispersion; and a toothed disc mixing element arranged in conjunction with the kneading block, the toothed disc mixing element being used to enhance the distribution mixing of the material.

[0018] Preferably, the screw elements in the homogenizing section are forward toothed elements and are equipped with a certain amount of small-angle kneading blocks.

[0019] Optionally, the screw elements of the twin-screw in the conveying section include conveying screw elements, which are used to establish extrusion pressure and convey materials.

[0020] Optionally, the feed inlet is connected to a premixing kettle arranged outside the unit through a diaphragm metering pump.

[0021] According to the technical content disclosed in this utility model, the following beneficial effects are achieved:

[0022] The twin-screw extruder provided by this utility model for dispersing carbon nanotube conductive slurries features a specific length-to-diameter ratio (L / D = 68-76) and a sixteen-section barrel structure precisely divided into four sections: a shearing section, a dispersion section, a homogenizing section, and a conveying section. Furthermore, dual motors drive two co-rotating screw shafts, ensuring that the material undergoes thorough shearing, mixing, and homogenization within the barrel. This structural design not only significantly enhances the ability to break up and disperse carbon nanotube agglomerates, ensuring uniform distribution of the carbon nanotubes within the slurry matrix, but also eliminates the need for traditional grinding media, eliminating the homogenizer and homogenization tank used in conventional conductive slurry processes. This simplifies the process, reduces production costs and equipment wear, and avoids potential contamination from grinding media.

[0023] Furthermore, the high aspect ratio of 68-76 provides sufficient residence time and active area for the full dispersion of carbon nanotubes. The dual-motor drive ensures strong and stable power output, effectively processing carbon nanotube slurries of varying viscosities and enabling continuous production, significantly improving production efficiency. Therefore, this utility model can efficiently and cost-effectively prepare a uniformly dispersed carbon nanotube conductive slurry, which has positive significance for improving the application performance of carbon nanotube materials and promoting their industrialization.

[0024] Other features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0026] Figure 1 The utility model is a structural schematic diagram of a twin-screw extruder unit for dispersing carbon nanotube conductive slurry.

[0027] Figure 2 The utility model is a top view of a twin-screw extruder unit for dispersing carbon nanotube conductive slurry.

[0028] Figure 3 The utility model is a schematic diagram of a control cabinet and a chiller connection of a twin-screw unit for dispersing carbon nanotube conductive slurry.

[0029] Explanation of the reference numerals: 11, main motor; 12, auxiliary motor; 21, main coupling; 22, auxiliary coupling; 31, main transmission box; 32, auxiliary transmission box; 4, twin screw; 41, main screw box; 42, auxiliary screw box; 5, barrel; 51, feed port; 511, first cooling water inlet; 512, first cooling water outlet; 513, first temperature measuring port; 52, shearing section; 521, second cooling water inlet; 522, second cooling water outlet; 523, second temperature measuring port; 53, dispersion section; 531, third cooling water inlet ; 532, the third cooling water outlet; 533, the third temperature measuring port; 54, the homogenizing section; 541, the fourth cooling water inlet; 542, the fourth cooling water outlet; 543, the fourth temperature measuring port; 55, the conveying section; 56, the discharge port; 6, the rack box; 7, the base; 8, the control cabinet; 81, the shearing section control area; 82, the dispersion section control area; 83, the homogenizing section control area; 84, the conveying section control area; 9, the chiller; 91, the shearing section cold water area; 92, the dispersion section cold water area; 93, the homogenizing section cold water area; 94, the conveying section cold water area. DETAILED DESCRIPTION

[0030] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention.

[0031] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present invention, its application, or uses.

[0032] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0033] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0034] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0035] The core concept of this utility model is to provide a twin-screw extruder with specific structural parameters. Through its unique aspect ratio, functional segmentation, dual-motor drive method, and the synergistic effect of the screw elements in each segment, it achieves efficient, uniform, and continuous dispersion of carbon nanotube conductive slurry without the use of grinding media. The unit is primarily composed of a drive system, an extrusion system, and an auxiliary control system.

[0036] Reference Figure 1 、 Figure 2 and Figure 3 The twin-screw extruder unit for dispersing carbon nanotube conductive slurry provided by the present invention is installed on a base 7 supporting a frame box 6. The frame box 6 carries the main working components of the unit.

[0037] The drive system of the present invention adopts a dual-motor drive design to provide sufficient and balanced power. Specifically, a main motor 11 and an auxiliary motor 12 are respectively arranged on opposite sides of the frame box 6. The main motor 11 is connected to the input shaft of the main transmission box 31 through the main coupling 21, and the output shaft of the main transmission box 31 is connected to the input shaft of the main screw box 41. Similarly, the auxiliary motor 12 is connected to the input shaft of the auxiliary transmission box 32 through the auxiliary coupling 22, and the output shaft of the auxiliary transmission box 32 is connected to the input shaft of the auxiliary screw box 42. The twin screw 4 includes two mutually meshing screw shafts, one end of which is connected to the output shaft of the main screw box 41, and the other end of the screw shaft is connected to the output shaft of the auxiliary screw box 42. In this way, the main motor 11 and the auxiliary motor 12 independently drive a screw shaft to rotate via their respective couplings, transmission boxes and screw boxes. Dual-motor drive is particularly important for twin-screw systems with a length-to-diameter ratio of up to 68-76. It can effectively avoid the problems of insufficient torque or uneven torque distribution that may occur when driven by a single motor, and ensure stable operation of the unit under high shear loads.

[0038] The extrusion system primarily consists of a barrel 5 and a twin screw 4 mounted within it. The twin screws 4 are two geometrically matched, parallel screws that rotate in the same direction. This co-rotation facilitates self-cleaning and efficient mixing of the material. The aspect ratio (L / D) of the active working portion of the twin screws (the ratio of the effective screw length L to the nominal screw diameter D) is 68-76, preferably 72. This significantly increases the effective length and residence time of the material within the screws, ensuring sufficient dispersion and homogenization of the carbon nanotubes.

[0039] The barrel 5 is fixed to the frame box 6, which internally forms the chamber that houses the twin screw 4. The barrel 5 is constructed from sixteen barrel sections of standard length, precisely connected axially. This modular design facilitates manufacturing, installation, maintenance, and adjustment of the barrel configuration to specific process requirements. The barrel material is selected to withstand the high temperatures, high pressures, and abrasive materials encountered during processing.

[0040] Along the flow direction of the material from the feed port 51 to the discharge port 56, the sixteen-section cylinder unit is precisely divided into four main functional sections. Each functional section is composed of four consecutive cylinder units, as follows:

[0041] Shearing section 52 (occupying barrel sections 1 to 4): This section is located at the feed end of the unit. A feed port 51 is provided on the first barrel section of the shearing section 52 and is used to receive the initial carbon nanotube slurry fed from an external premixing system. The screw elements of the twin-screw extruder 4 within the shearing section 52 are configured to include: a conveying screw element, whose primary function is to effectively grasp and convey the incoming material, establishing an initial material filling; and a kneading block configured in conjunction with the conveying screw element. The kneading block's geometric parameters are configured to exert an initial shearing and mixing action on the material, aiming to break up larger carbon nanotube agglomerates in the slurry and promote initial wetting and mixing of the carbon nanotubes with the matrix. The shear strength of this section is designed to be relatively mild to avoid excessive shearing that could lead to excessive temperature rise or premature structural damage.

[0042] Preferably, the screw elements in the shearing section are toothed elements with a large spiral angle (60°-90°) and are equipped with a certain amount of reverse thread elements.

[0043] Dispersion section 53 (occupying barrel units 5 to 8): This section follows the shearing section 52 and is the core area for achieving efficient dispersion of carbon nanotubes. The screw elements of the twin-screw extruder 4 within the dispersion section 53 are configured to include: multiple sets of kneading blocks of varying thicknesses and staggered angles, configured to exert strong shearing, stretching, and extrusion effects on the material; and toothed disc mixing elements configured in conjunction with the kneading blocks. The toothed disc mixing elements, through their unique tooth structure, can exert strong tearing, splitting, cutting, and high-frequency stretching and folding effects on the material. The combination of these strong shear elements generates extremely high shear stress fields and complex flow fields in the screw meshing zone and the gap between the screw flight and the barrel wall, forcibly exfoliating and refining carbon nanotube agglomerates, promoting their microscopic dispersion within the matrix.

[0044] Preferably, the screw elements in the dispersion section are tooth-shaped elements with a small angle (10° to 30°) and are equipped with a certain number of porous plates.

[0045] Homogenizing section 54 (occupying barrel units 9 through 12): This section, located after the dispersion section 53, is primarily responsible for achieving a higher degree of uniformity in the distribution and size of the carbon nanotubes dispersed through the intense shearing process throughout the slurry system, eliminating any local concentration gradients and residual microagglomerates. The screw elements of the twin-screw extruder 4 within homogenizing section 54 are configured to include a kneading block, whose geometric parameters are configured to apply shear to the material to improve dispersion uniformity, and a toothed disc mixing element, coupled with the kneading block, which enhances radial mixing and axial material exchange and redistribution. The specific combination and geometric configuration of the kneading block and toothed disc mixing element in this section further emphasizes the segmentation, disruption, and reorientation of the material, promoting uniform dispersion of the dispersed phase within the matrix, thereby achieving a highly uniform slurry both macroscopically and microscopically.

[0046] Preferably, the screw elements in the homogenizing section are forward toothed elements and are equipped with a certain amount of small angle (10°~30°) kneading blocks.

[0047] Conveying section 55 (occupying barrel sections 13 through 16): This section serves as the terminal functional zone of the extruder unit. The end of the last (i.e., 16th) barrel section is equipped with a discharge port 56, through which the material is extruded. The screw elements of the twin-screw extruder 4 within conveying section 55 are configured to include conveying screw elements for establishing extrusion pressure and conveying the material. These conveying screw elements typically have a large thread lead and positive conveying capacity. Their primary function is to stably convey the fully dispersed and homogenized carbon nanotube conductive paste forward and to establish sufficient pressure at the discharge port 56 to ensure smooth and continuous extrusion of the paste for subsequent collection or molding.

[0048] In order to ensure the stability and controllability of the dispersion process, the utility model also includes the following auxiliary control systems:

[0049] Temperature control system: The dispersion process of carbon nanotubes is often accompanied by significant shear heat generation, so accurate temperature control is crucial. To this end, each of the shearing section 52, the dispersion section 53, the homogenizing section 54, and the conveying section 55 is equipped with independent cooling water inlets and outlets for accurate temperature control, and temperature measuring ports are provided at key locations in each section to monitor the temperature. Specifically, refer to Figure 1 and Figure 2 The layout of these cooling and temperature measuring devices is shown below: the shearing section 52 is provided with a first cooling water inlet 511, a first cooling water outlet 512, and a first temperature measuring port 513; the dispersion section 53 is provided with a second cooling water inlet 521, a second cooling water outlet 522, and a second temperature measuring port 523; the homogenization section 54 is provided with a third cooling water inlet 531, a third cooling water outlet 532, and a third temperature measuring port 533; and the conveying section 55 is provided with a fourth cooling water inlet 541, a fourth cooling water outlet 542, and a fourth temperature measuring port 543. It should be noted that for precise control, cooling channel interfaces and temperature measuring points may be physically provided on the multi-section cylinder units within each functional section. However, primary control and monitoring is performed on these four functional sections using the devices indicated by the corresponding reference numerals. These inlets and outlets are connected to the cooling jacket or cooling channels on the exterior of the cylinder, allowing cooling water (or other suitable cooling medium) to circulate through them to effectively remove heat generated during processing. The temperature measuring port is equipped with a built-in temperature sensor to monitor the material or cylinder wall temperature in this area in real time.

[0050] The unit is equipped with a central control cabinet 8 and a chiller 9. The control cabinet 8 integrates a programmable logic controller (PLC) or a dedicated multi-zone temperature controller, for example, a shearing section control zone 81, a dispersion section control zone 82, a homogenization section control zone 83, and a conveying section control zone 84. These control zones are electrically connected to temperature sensors in their respective sections, receiving real-time temperature feedback signals. Based on preset target temperatures and a control algorithm (such as PID control), the controller precisely controls the cooling water flow to each section by adjusting the opening of the electric control valves connected to the cooling water circuits of each section, thereby achieving independent and precise temperature control of each functional section. The chiller 9 (which can provide water supply by zone and temperature, such as the shearing section cooling water zone 91, the dispersion section cooling water zone 92, the homogenization section cooling water zone 93, and the conveying section cooling water zone 94) provides stable, low-temperature cooling circulating water for the entire cylinder 5 cooling system. Precise temperature control helps optimize material viscosity and prevents thermal degradation of materials (especially polymer matrices or solvents) or damage to the carbon nanotube structure due to excessive shear heat, thereby ensuring the stability of the dispersion process and the consistency of the final product quality.

[0051] Feed System: As a preferred embodiment, feed port 51 is connected to a premixing vessel (not shown) located outside the unit via a diaphragm metering pump (not shown, a common configuration in the art). The premixing vessel is used to prepare an initial mixture of carbon nanotubes and matrix materials (such as solvents and resins). The diaphragm metering pump enables precise control and stable delivery of the slurry flow, ensuring a constant feed rate during continuous operation of the twin-screw extruder. This is crucial for ensuring uniform dispersion and process stability.

[0052] Brief description of the working process:

[0053] In actual operation, carbon nanotube powder, liquid base material (such as solvent, resin) and other additives (such as dispersant) that may be required are first preliminarily mixed in a premixing kettle to form an initial slurry with a certain fluidity.

[0054] Start the twin-screw extruder unit and set process parameters such as the speed of twin-screw 4 and the target temperatures of each functional section (shearing section 52, dispersion section 53, homogenization section 54, and conveying section 55) through control cabinet 8. Chiller 9 begins supplying cooling water.

[0055] The initial slurry in the premix kettle is then continuously and quantitatively pumped from the feed port 51 into the shearing section 52 of the twin-screw extruder via a diaphragm metering pump. The material is initially conveyed, mixed, and sheared within the shearing section 52. It then enters the dispersion section 53 and homogenization section 54, where the intense shearing, kneading, stretching, segmentation, and mixing generated by the specific screw configurations in each section effectively disintegrate the carbon nanotube agglomerates and evenly disperse them into the matrix. Finally, the uniformly dispersed carbon nanotube conductive slurry is stably extruded from the discharge port 56 via the conveying section 55 and can be collected for subsequent coating, molding, spinning, and other processes. The entire process is continuous, requiring no added grinding media.

[0056] Through the above-mentioned careful structural design and system configuration, especially the ultra-long-diameter ratio (L / D=72), precise four-section functional division (each section has 4 cylinders), dual-motor independent drive and precise temperature control system, the utility model provides an efficient, continuous, low-cost dispersion solution for the preparation of carbon nanotube conductive slurry without the need for grinding media, which can significantly improve the application performance and industrialization level of carbon nanotube materials.

[0057] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art will appreciate that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art will appreciate that modifications may be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A twin-screw extruder unit for dispersing carbon nanotube conductive slurry, comprising a frame box, a base supporting the frame box, a main motor and an auxiliary motor arranged on opposite sides of the frame box, a main transmission box, an auxiliary transmission box, a main screw box, an auxiliary screw box respectively connected to the main motor and the auxiliary motor, and a twin screw arranged in a barrel; the barrel is fixed to the frame box, and the twin screw comprises two mutually meshing screw shafts, one of the screw shafts is driven by the main motor, the main coupling, the main transmission box, and the main screw box, which are sequentially connected, and the other screw shaft is driven by the auxiliary motor, the auxiliary coupling, the auxiliary transmission box, and the auxiliary screw box; the barrel is provided with a feed port and a discharge port; and the characteristics are: The twin screws are twin screws that rotate in the same direction. The length-to-diameter ratio L / D of the effective working part of the twin screw is 68-76; The cylinder is composed of sixteen cylinder units of standard length connected along the axial direction, and is divided into a shearing section, a dispersion section, a homogenizing section, and a conveying section in the direction of material flow; the shearing section, the dispersion section, the homogenizing section, and the conveying section are each composed of four cylinder units; The feed port is arranged on the first section of the cylinder unit of the shearing section, and the discharge port is arranged on the last section of the cylinder unit of the conveying section.

2. The twin-screw extruder for dispersing carbon nanotube conductive slurry according to claim 1, characterized in that: The outside of each cylinder of the shearing section, the dispersing section, the homogenizing section and the conveying section is provided with an independent cooling water inlet and cooling water outlet, and each cylinder is provided with a temperature measuring port.

3. The twin-screw extruder for dispersing carbon nanotube conductive slurry according to claim 2, characterized in that: Each section of the cylindrical unit of the shearing section, the dispersing section, the homogenizing section and the conveying section is provided with an independent cooling water inlet and cooling water outlet on the outside, and each section of the cylindrical unit is provided with a temperature measuring port.

4. The twin-screw extruder for dispersing carbon nanotube conductive slurry according to claim 2, characterized in that: The twin-screw unit also includes a control cabinet and a chiller; the control cabinet is electrically connected to each of the temperature measuring ports for independently controlling the temperature of the shearing section, the dispersion section, the homogenizing section and the conveying section; the chiller is connected to each of the cooling water inlets and cooling water outlets through pipelines.

5. The twin-screw extruder for dispersing carbon nanotube conductive slurry according to claim 1, characterized in that: The screw elements of the twin-screw in the conveying section include conveying flight elements, which are used to build up extrusion pressure and convey materials.

6. The twin-screw extruder for dispersing carbon nanotube conductive slurry according to claim 1, characterized in that: The feed port is connected to a premixing kettle arranged outside the unit through a diaphragm metering pump.

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