A method and control system for measuring the resistivity gradient of integrated black ink

Abstract

This invention relates to the field of ink resistivity measurement technology, and discloses a method and control system for measuring the resistivity gradient of integrated black ink. The method includes: dispersing conductive carbon black and a fast-drying solvent in a high-speed disperser to obtain a percolated carbon black slurry; coating the percolated carbon black slurry onto a substrate, applying a pulsed magnetic field and calculating the resistivity gradient between the film surface and the substrate; when the resistivity gradient exceeds a preset threshold, calculating the dispersant injection flow rate and controlling a micro-pump to inject dispersant to achieve a shear rate within a set range, thus obtaining a coating slurry; calculating the thixotropic index of the coating slurry and calculating the set temperature values ​​for the first, second, and third temperature zones of the drying section; and obtaining a cured film through a curing process. This method achieves control from thixotropic protection and resistivity gradient reduction to rapid curing, realizing the rapid and uniform construction of the conductive network of integrated black ink and improving the uniformity of the film resistivity distribution.

Description

Technical Field

[0001] This invention relates to the field of ink resistivity measurement technology, and in particular to a method and control system for measuring the resistivity gradient of an integrated black ink. Background Technology

[0002] As a key conductive material for electronic devices, the uniformity of the conductive network within the integrated black ink film directly affects product performance. In traditional preparation processes, the dispersion of conductive carbon black relies on empirical time control, making it impossible to accurately determine whether the carbon black has reached the critical concentration for the percolation state required to form a continuous conductive pathway, resulting in unstable dispersion. Existing technologies can only measure surface resistivity using contact methods after film curing, and cannot obtain real-time resistivity distribution information at different depths within the film in the wet state. When uneven resistivity distribution is detected, it is impossible to adjust the process. Summary of the Invention

[0003] This invention provides a method and control system for measuring the resistivity gradient of integrated black ink. This invention achieves control from thixotropic protection and resistivity gradient reduction to rapid curing, realizing the rapid and uniform construction of the conductive network of integrated black ink and improving the uniformity of the resistivity distribution of the film layer.

[0004] In a first aspect, the present invention provides a method for measuring the resistivity gradient of an integral black ink, the method comprising: Conductive carbon black and fast-drying solvent are dispersed in a high-speed disperser, and the conductivity of the slurry is monitored from the initial value to the target value to obtain a percolating carbon black slurry. The percolating carbon black slurry was coated onto the substrate, a pulsed magnetic field was applied, and the resistivity gradient between the film surface and the bottom layer was calculated. When the resistivity gradient exceeds a preset threshold, the carbon black agglomeration index is calculated; The dispersant injection flow rate is calculated based on the carbon black agglomeration index and the resistivity gradient, and the dispersant is injected by a micro-pump to make the shear rate reach the set range, thereby obtaining the coating slurry. The thixotropic index of the coating slurry is calculated, and the set temperature values ​​of the first, second, and third temperature zones of the drying section are calculated based on the thixotropic index. A cured film layer is obtained through curing treatment.

[0005] In conjunction with the first aspect, in a first implementation of the first aspect of the present invention, the step of dispersing conductive carbon black and a fast-drying solvent in a high-speed disperser and monitoring the conductivity of the slurry from an initial value to a target value to obtain a percolated carbon black slurry includes: Conductive carbon black is added to a fast-drying solvent and mechanically sheared in a high-speed disperser. Simultaneously, ultrasonic cavitation is applied to break up the secondary agglomerates of carbon black to obtain a primary dispersion slurry. Add ammonium polyacrylate dispersant to the primary dispersion slurry and continue mixing and dispersing to obtain a carbon black slurry containing dispersant; The conductivity of the carbon black slurry containing dispersant was monitored in real time using a four-electrode method. When the conductivity jumped from the initial value to the target value, it was determined that the percolation transition point had been reached and the dispersion process was stopped, thus obtaining the percolation state carbon black slurry.

[0006] In conjunction with the first aspect, in a second implementation of the first aspect of the present invention, the step of coating the percolating carbon black slurry onto the substrate, applying a pulsed magnetic field, and calculating the resistivity gradient between the film surface and the substrate includes: The percolating carbon black slurry is coated onto the substrate through a coating head to form a wet film to be tested. After the wet film to be tested passes through the coating unit outlet, an eddy current induction coil array is used to apply a pulsed magnetic field to the wet film layer and calculate the time-domain decay curve of the induced electromotive force at different depth positions. Extract the induced electromotive force value at the initial moment and the induced electromotive force value at the target moment from the induced electromotive force time-domain decay curve. Calculate the surface resistivity of the film surface layer and the bottom resistivity of the film layer based on the logarithm of the ratio of the induced electromotive force value at the initial moment to the induced electromotive force value at the target moment. The resistivity gradient between the surface layer and the bottom layer is obtained by calculating the ratio of the absolute value of the difference between the surface resistivity and the bottom layer resistivity to the depth difference between the surface layer depth and the bottom layer depth.

[0007] In conjunction with the first aspect, in a third implementation of the first aspect of the present invention, the step of applying a pulsed magnetic field to the wet film layer using an eddy current induction coil array and calculating the time-domain decay curves of the induced electromotive force at different depth positions after the wet film to be tested passes through the coating unit outlet includes: An array of eddy current induction coils is deployed at the location where the wet film to be tested passes through the coating unit; A pulsed magnetic field is applied to the eddy current induction coil array to penetrate the wet film layer. The conductive carbon black network in the wet film layer generates induced eddy currents, which decay and then generate induced electromotive force signals in each coil in the opposite direction. The induced electromotive force (EMF) signal output by each coil in the eddy current induction coil array is collected, and the amplitude of the induced EMF is calculated based on the induced EMF signal. The change of the amplitude of the induced electromotive force at different coil positions over time is plotted as a curve to obtain the time-domain decay curve of the induced electromotive force at different depth positions.

[0008] In conjunction with the first aspect, in a fourth implementation of the first aspect of the present invention, the step of calculating the carbon black agglomeration index when the resistivity gradient exceeds a preset threshold includes: When the resistivity gradient exceeds a preset threshold, a bypass circulation loop is led out from the slurry supply pipeline at the front end of the coating head to transport the slurry to the measuring cell of the online laser particle size analyzer for real-time particle size detection. A laser beam is used to irradiate carbon black particles in the slurry through a measuring cell. The scattered light signals generated by particles of different sizes are collected by a multi-angle photodetector array, and the particle size distribution is calculated based on the Mie scattering theory to obtain the volume-weighted average particle size. The carbon black agglomeration index is obtained by calculating the ratio of the volume-weighted average particle size to the initial particle size of the conductive carbon black.

[0009] In conjunction with the first aspect, in a fifth implementation of the first aspect of the present invention, the step of calculating the dispersant injection flow rate based on the carbon black agglomeration index and the resistivity gradient, and controlling the micro-pump to inject the dispersant so that the shear rate reaches a set range to obtain the coating slurry, includes: The dispersant injection flow rate is obtained by multiplying the square of the carbon black agglomeration index by the exponential function obtained by multiplying the resistivity gradient by the first coefficient, and then multiplying by the second coefficient. Adjust the pumping frequency of the micro-pump according to the dispersant injection flow rate so that the dispersant is injected into the front end of the coating head through the injection nozzle; By synchronously adjusting the coating speed or the doctor blade gap to change the wet film thickness, the shear rate of the coating speed and the wet film thickness reaches the set range, thus obtaining the coating slurry.

[0010] In conjunction with the first aspect, in a sixth implementation of the first aspect of the present invention, the step of multiplying the square of the carbon black agglomeration index by the exponential function obtained by multiplying the resistivity gradient by a first coefficient and then by a second coefficient to obtain the dispersant injection flow rate includes: The agglomeration index of the carbon black is squared to obtain the squared value of the agglomeration index; The resistivity gradient is multiplied by the first coefficient and then used as the power of the exponential function for exponential operation with the natural constant as the base, to obtain the resistivity gradient exponential function value. The dispersant injection flow rate is obtained by multiplying the squared value of the aggregation index with the value of the resistivity gradient exponential function and then multiplying by a second coefficient.

[0011] In conjunction with the first aspect, in the seventh implementation of the first aspect of the present invention, the step of calculating the thixotropic index of the coating slurry, calculating the set temperature values ​​of the first temperature zone, the second temperature zone, and the third temperature zone of the drying section based on the thixotropic index, and obtaining a cured film layer through a curing process includes: The coating slurry is led out from the coating head outlet and conveyed to the cone-plate measurement system of the rotational rheometer; A two-step shear rate test procedure was performed on the coating slurry. First, a first shear rate was applied until a steady state was reached, and then the first shear viscosity was measured. Then, a second shear rate was applied until a steady state was reached, and then the second shear viscosity was measured. The ratio of the first shear viscosity to the second shear viscosity is calculated to obtain the thixotropic index; The set temperature values ​​of the first temperature zone, the second temperature zone, and the third temperature zone in the drying section are calculated based on the thixotropic index, and then cured to obtain a cured film layer.

[0012] In conjunction with the first aspect, in the eighth implementation of the first aspect of the present invention, the step of calculating the set temperature values ​​of the first temperature zone, the second temperature zone, and the third temperature zone in the drying section based on the thixotropic index and performing a curing process to obtain a cured film layer includes: Calculate the set temperature values ​​for the first temperature zone, the second temperature zone, and the third temperature zone based on the thixotropic index. The heater in the first temperature zone of the drying section is controlled to reach the set temperature value of the first temperature zone for thixotropic protection treatment. The heater in the second temperature zone of the drying section is controlled to reach the set temperature value of the second temperature zone to reduce the resistivity gradient. The heater in the third temperature zone of the drying section is controlled to reach the set temperature value of the third temperature zone for rapid curing to obtain a cured film layer.

[0013] In a second aspect, the present invention provides a control system, the control system comprising: The dispersion module is used to disperse conductive carbon black and fast-drying solvent in a high-speed disperser and monitor the conductivity of the slurry from the initial value to the target value to obtain a percolated carbon black slurry. A coating module is used to coat the percolated carbon black slurry onto a substrate, apply a pulsed magnetic field, and calculate the resistivity gradient between the film surface and the substrate. The calculation module is used to calculate the carbon black agglomeration index when the resistivity gradient exceeds a preset threshold. The injection module is used to calculate the dispersant injection flow rate based on the carbon black agglomeration index and the resistivity gradient, and control the micro-pump to inject the dispersant so that the shear rate reaches a set range to obtain the coating slurry. The curing module is used to calculate the thixotropic index of the coating slurry and, based on the thixotropic index, calculate the set temperature values ​​of the first, second, and third temperature zones of the drying section, and obtain a cured film layer through curing treatment.

[0014] The technical solution provided by this invention uses a four-electrode method to monitor the percolation transition characteristics of the slurry conductivity in real time, accurately determining the dispersion endpoint and ensuring that the carbon black concentration falls within the critical percolation range, thus laying a theoretical foundation for the construction of the conductive network. By employing an eddy current induction coil array to apply a pulsed magnetic field and acquire the time-domain decay curve of the induced electromotive force, non-contact real-time measurement of the resistivity at different depths of the film layer in the wet film state is achieved. When the resistivity gradient exceeds a preset threshold, online laser particle size analysis is immediately triggered to calculate the carbon black agglomeration index. Based on the nonlinear coupling function between the agglomeration index and the resistivity gradient, the dispersant injection flow rate is dynamically calculated, and the shear rate is adjusted synchronously, achieving dual-dimensional intelligent collaborative control of the carbon black dispersion state and effectively suppressing dynamic agglomeration behavior during the coating process. By measuring the thixotropic index using a rotational rheometer, and calculating the set values ​​for three temperature zones based on the thixotropic index-driven graded temperature field distribution algorithm, control from thixotropic protection and resistivity gradient reduction to rapid curing is achieved, realizing the rapid and uniform construction of the integrated black ink conductive network and improving the uniformity of the film layer resistivity distribution.

[0015] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an embodiment of the resistivity gradient measurement method for integrated black ink in this invention; Figure 2 This is a schematic diagram of one embodiment of the control system in this invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The terms "comprising" and "having," and any variations thereof, used in the embodiments of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include other steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0020] To facilitate understanding of this embodiment, a detailed description of the resistivity gradient measurement method for integral black ink disclosed in this embodiment of the invention will be provided first. For example... Figure 1 As shown, this method includes the following steps: 101. Conductive carbon black and fast-drying solvent are dispersed in a high-speed disperser, and the conductivity of the slurry is monitored from the initial value to the target value to obtain a percolating carbon black slurry; Specifically, a fast-drying solvent mixture of ethyl acetate and butanone at a mass ratio of 7:3 is selected as the dispersion medium. A high-speed disperser is started in the reactor to provide a stable shear field with the dispersion disc rotating at 2800-3200 rpm. At the same time, conductive carbon black powder with a particle size distribution between 18-25 nm is slowly added to the solvent system at a volume fraction controlled within the percolation critical concentration range of 16-19%. During the formation of the primary dispersed phase, an ultrasonic cavitation treatment device is introduced. The ultrasonic probe penetrates 30-50 mm below the slurry surface and applies high-intensity ultrasonic excitation with a frequency of 28 kHz and a power of 600 W. This utilizes the synergistic effect of microjets and cavitation shock waves to break up the original secondary agglomerates in the carbon black, improve the dispersion uniformity and specific surface area of ​​the carbon black particles, and form a preliminary uniform primary dispersion slurry. Ammonium polyacrylate dispersant was added to the primary dispersion slurry under continuous stirring and ultrasonic treatment, with the dispersant accounting for 0.5-1.2 wt% of the total slurry mass. The dispersant molecular chains rapidly expanded and adsorbed onto the surface of carbon black particles under mechanical shearing, suppressing the re-agglomeration tendency of carbon black particles through steric hindrance and electrostatic repulsion mechanisms, resulting in a stable carbon black slurry containing the dispersant. Throughout the dispersion process, the slurry system was continuously monitored in real time using a four-electrode conductivity measurement probe installed on the side of the reactor wall. The probe consisted of four platinum electrodes arranged in a square. An AC excitation signal with an amplitude of 10-15 V and a frequency of 1 kHz was applied to the outer two electrodes, while the inner two electrodes synchronously acquired the potential difference signal. The conductivity of the slurry was calculated in real time by an electrochemical workstation. When the conductivity changed from approximately 10V initially... -8 S / cm increased by an order of magnitude to 10 -2 When the S / cm ratio is above a certain value, it indicates that a continuous conductive path has been formed between the conductive carbon blacks and the percolation state transition point of the conductive network has been reached. At this point, the dispersion operation should be stopped immediately to obtain an integral black percolation state carbon black slurry with a uniform conductive structure.

[0021] 102. Apply the percolating carbon black slurry to the substrate, apply a pulsed magnetic field and calculate the resistivity gradient between the film surface and the substrate. Specifically, percolating carbon black slurry is uniformly coated onto the surface of the composite substrate using a coating head configured with a doctor blade structure. The coating speed is controlled within the range of 15-25 meters per minute, maintaining the wet film thickness of the slurry layer between 80-120 micrometers. The conductive carbon black forms a preliminary continuous conductive network structure in the slurry state, exhibiting representative longitudinal distribution characteristics. Approximately 5-8 seconds after the coated substrate exits the coating unit, an array of 15-25 flat spiral structures of eddy current induction coils is laid along the conveying path. The eddy current induction coil array is arranged perpendicularly along the film thickness direction, with a center-to-center spacing of approximately 5 millimeters between adjacent coils. Each coil is wound with copper wire of 0.15-0.20 millimeters in diameter, and its outer diameter is controlled between 8-12 millimeters, exhibiting good pulsed magnetic field coupling characteristics. During the induction measurement phase, a rectangular pulse current with an excitation frequency of 15 kHz, a pulse width of 50-80 microseconds, and a peak current of 2-3 amperes is applied to the eddy current coil array. This instantaneously excites a pulsed magnetic field with an amplitude of 3000-5000 A / m within the film layer. The magnetic field propagates in an exponential decay manner over time. After penetrating into the film layer, the magnetic field excites local eddy currents and induces an electromotive force (EMF). The decay rate of the induced EMF is affected by the carbon black distribution and the connectivity of the conductive path at that depth, thus indirectly reflecting the instantaneous resistivity at that location. The time-domain decay curves of the induced EMF of each coil are simultaneously acquired within a time window of 0-200 microseconds. The induced EMF values ​​at each depth point at the initial time (t=0) and the set target time (e.g., t=50 microseconds) are extracted. Then, through logarithmic calculation, the instantaneous resistivity value at the corresponding depth z is obtained using the eddy current decay characteristics reflected by the ratio of the induced EMFs. Two measurement points are selected in the film layer: the surface layer in the 10-15 micrometer region and the bottom layer in the 70-90 micrometer region. The corresponding resistivity is read. The resistivity gradient is obtained by calculating the ratio of the absolute value of the difference to the depth difference. This allows for the evaluation of the uniformity of the conductive structure distribution along the thickness direction of the coated film layer in a non-contact, real-time, wet film state.

[0022] 103. When the resistivity gradient exceeds a preset threshold, calculate the carbon black agglomeration index; Specifically, when the resistivity gradient value measured by the eddy current induction coil array during the coating process exceeds the set threshold of 2.8 × 10⁻⁶, 3When the carbon black concentration is Ω·cm / mm, it is determined that the distribution of conductive carbon black in the film layer is non-uniform along the thickness direction. It is preliminarily inferred that the carbon black particles inside the slurry have undergone different degrees of re-agglomeration during the coating process. In order to identify the actual intensity and distribution characteristics of the agglomeration behavior, the particle size detection module is activated, and a bypass circulation loop is led out from the slurry supply main pipeline at the front end of the coating head. The slurry flow rate is controlled between 80-120mL / min by a constant flow pump, and the slurry is continuously introduced into the measuring cell of the online laser particle size analyzer. The optical path length of the measuring cell is 5-10mm, and high-transparency quartz windows are configured on both sides to ensure laser penetration performance. In the particle size analysis stage, a stable laser beam emitted from a 632.8 nm He-Ne laser passes through the measurement cell and irradiates carbon black particles suspended in the slurry. The particles undergo Mie scattering under the laser's influence, and the light intensity distribution exhibited by particles of different sizes at different scattering angles shows significant differences. A multi-angle photodetector array (covering an angle range of 0.02° to 135°) installed outside the measurement cavity synchronously collects the intensity of the scattered light signal. Based on the Mie scattering inversion algorithm, the light intensity distribution is analytically reconstructed to obtain the volume distribution curve of the carbon black particles in the slurry at the current moment. Real-time integration calculations are performed on the particle size distribution data to extract the volume-weighted average particle size D. 43 As the main characteristic quantity describing the current degree of agglomeration of carbon black, D 43 A higher D value indicates a higher volume fraction of large-size aggregates in the particulate system. 43 Value and the original particle size D of conductive carbon black before dispersion 10 By performing ratio calculations, the carbon black agglomeration index AI=D is obtained. 43 / D 10 This allows for the quantitative evaluation of the agglomeration amplification factor of carbon black from its initial state to its current state. The carbon black agglomeration index reflects the actual particle size evolution characteristics of the carbon black system in the coating slurry. If AI is much greater than 1, it indicates a significant agglomeration trend during the coating and conveying process, which needs to be corrected through dispersant compensation and shear rate adjustment.

[0023] 104. Calculate the dispersant injection flow rate based on the carbon black agglomeration index and resistivity gradient, and control the micro-pump to inject the dispersant so that the shear rate reaches the set range to obtain the coating slurry; Specifically, the carbon black agglomeration index is processed twice, and the resistivity gradient is then introduced into an exponential growth model. The results of the two parts are multiplied to construct a flow output function. This function, after fitting, determines two constant parameters that reflect the nonlinear enhancement effect of carbon black agglomeration degree and coating film resistivity non-uniformity on the dispersant demand. The dispersant injection flow rate calculated based on the flow output function is used as the control target for the micro-plunger pump. By adjusting the pumping frequency, the actual injection flow rate is matched, and the dispersant solution is introduced into the slurry main channel at the front end of the coating head through a nozzle at a certain angle. The slurry is thoroughly mixed by a static mixer with a multi-stage spiral structure, ensuring uniform distribution of the newly injected dispersant and rapid adsorption onto the carbon black particle surface during subsequent shearing, thus enhancing its dispersion stability. Meanwhile, by measuring the relationship between coating speed and wet film thickness in real time, the current shear rate is dynamically calculated, and the shear rate is maintained within a preset reasonable range by adjusting the conveying speed of the coating machine or the doctor blade gap as needed. This range can fully activate the dispersant's mechanism of action, allowing its molecular chain segments to extend, adsorb, and stabilize the carbon black dispersion state in a high shear field, effectively preventing agglomeration.

[0024] 105. Calculate the thixotropic index of the coating slurry, and calculate the set temperature values ​​of the first, second, and third temperature zones of the drying section based on the thixotropic index. Obtain the cured film layer through curing treatment.

[0025] Specifically, the coating slurry drawn from the coating head outlet is pumped via a stable flow pump into the measurement chamber of a rotational rheometer equipped with a cone-plate structure. The cone angle of the cone-plate measurement system is controlled at 1-2 degrees, the cone diameter is 25-35 mm, and the measurement gap is 50-70 micrometers, to achieve high-resolution strain response detection under controlled shear conditions. The temperature of the measurement chamber is maintained constant at 25±0.5℃ to eliminate thermal disturbance. The double-step shear rate test program is initiated, and the first shear rate is applied for 10 seconds. -1 The process continues for 30 seconds to allow the sample to reach a steady state; the apparent viscosity measured during this phase is the first shear viscosity. The process is then switched to the second shear rate of 1000 s. -1The steady-state apparent viscosity was measured again under high shear conditions for 30 seconds and taken as the second shear viscosity. The ratio of the first shear viscosity to the second shear viscosity was used as the thixotropic index to quantitatively characterize the slurry's structural recovery ability and viscosity decay in a shear field. A larger thixotropic index indicates a more stable structure in the slurry under static or low shear conditions, which is more conducive to suppressing the migration and rearrangement of conductive carbon black particles. The thixotropic index was input into the temperature field allocation algorithm model, and combined with the basic temperature parameters of 60-70℃, thixotropic sensitivity coefficient of 45, and depth decay coefficient of 0.08, as well as the spatial positions of the three zones (2-3 meters, 4-5 meters, and 6-7 meters), the target set temperature values ​​for the first, second, and third temperature zones were calculated through function mapping relationships. The set temperature range for the first temperature zone was 85-95℃, used to maintain a structural protection state with a TI greater than 2.5 to prevent premature migration of carbon black in the thixotropic state; the set temperature range for the second temperature zone was 75-85℃, used to reduce the resistivity gradient to 1.5×10 while ensuring slow rearrangement of carbon black. 3 Below Ω·cm / mm; the third temperature zone is set at 105-120℃ to rapidly cure the carbon black network structure and reduce residual solvent to below 1%, achieving end-point physical locking. Through a thixotropic index-driven graded temperature control mechanism, the carbon black undergoes three stages—structural protection, slow-release rearrangement, and rapid locking—during the entire drying process after coating, forming a uniform and stable conductive network, and obtaining a cured film with excellent physical properties during the thermal curing process.

[0026] In one specific embodiment, the process of performing step 101 may specifically include the following steps: Conductive carbon black is added to a fast-drying solvent and mechanically sheared in a high-speed disperser. Simultaneously, ultrasonic cavitation is applied to break up the secondary agglomerates of carbon black to obtain a primary dispersion slurry. Ammonium polyacrylate dispersant was added to the primary dispersion slurry and the mixture was continued to disperse to obtain a carbon black slurry containing the dispersant. The conductivity of the carbon black slurry containing dispersant was monitored in real time using a four-electrode method. When the conductivity jumped from the initial value to the target value, it was determined that the percolation transition point had been reached and the dispersion process was stopped, thus obtaining the percolation state carbon black slurry.

[0027] Specifically, a fast-drying solvent mixture of ethyl acetate and butanone at a mass ratio of 7:3 was selected as the dispersion medium and injected into a reactor equipped with a high-speed dispersion device. The dispersion disk was driven at 2800 to 3200 rpm to create a high-intensity shear flow field. Conductive carbon black powder with an average particle size distribution of 18 to 25 nanometers was uniformly added to the solvent system at a volume fraction controlled within the range of 16% to 19%. As the carbon black particles were entrained and impacted by the high-speed flow field, the initial agglomerates were partially disintegrated. However, due to the high specific surface area and strong hydrophobicity of the carbon black surface, mechanical shearing alone was insufficient to completely break down the secondary agglomerates. Therefore, ultrasonic cavitation energy was simultaneously applied during the dispersion process. An ultrasonic probe with a power of 600 watts and a frequency of 28 kHz was immersed approximately 30 to 50 millimeters below the liquid surface. The transient microjets, shock waves, and microbubble collapse effects generated by ultrasonic cavitation were used to peel and impact the weak bonding interfaces between carbon black particles, disrupting the van der Waals forces between the particles and gradually disintegrating the aggregates into a monodisperse state with uniform particle size. After 15 to 22 minutes of synergistic action, a highly stable primary dispersion slurry was formed, at which point the carbon black particles were uniformly suspended in the solvent and formed preliminary conductive paths. While maintaining stirring, ammonium polyacrylate dispersant was added to the system at a mass fraction of 0.5% to 1.2% of the total slurry mass. This dispersant rapidly dechained and adsorbed onto the carbon black surface under high shear field, relying on the charge repulsion provided by its carboxyl ionization and the steric hindrance formed by the molecular chain segments to jointly construct a stable anti-agglomeration barrier. At this point, a dynamic equilibrium system gradually forms in the system, consisting of carbon black particles, dispersant molecules, and solvent molecules. The rheological properties and conductivity of the slurry change with the evolution of the interactions between carbon black particles. To determine whether the conductive network has reached a continuous state, a four-electrode conductivity measurement probe is installed on the reactor wall. The four platinum electrodes are arranged in a square array, with the electrode spacing controlled at 8 to 12 mm and the electrode diameter at 1.5 to 2.0 mm. The two outer electrodes are connected to an AC excitation source to apply an electrical signal with an amplitude of 10 to 15 volts and a frequency of 1 kHz. The two inner electrodes collect the instantaneous potential difference signal and analyze it through an electrochemical workstation to calculate the conductivity of the system in real time. When the monitoring results show that the conductivity changes from the initial state of 10... -8 Siemens jumps to 10 per centimeter -2 When the Siemens value is 1 cm per centimeter, it indicates that a continuous conductive network has formed between the carbon black particles and the percolation transition point has been reached, meaning that the conductive paths within the system have changed from isolated distribution to continuous connection. At this point, dispersion and ultrasonic operation are stopped, resulting in a percolated carbon black slurry.

[0028] In one specific embodiment, the process of performing step 102 may specifically include the following steps: The permeable carbon black slurry is applied to the substrate through a coating head to form a wet film to be tested. After the wet film to be tested passes through the coating unit outlet, an eddy current induction coil array is used to apply a pulsed magnetic field to the wet film layer and calculate the time-domain decay curve of the induced electromotive force at different depth positions. Extract the induced electromotive force (EMF) value at the initial moment and the induced EMF value at the target moment from the time-domain decay curve of the induced EMF. Calculate the surface resistivity of the film surface layer and the bottom resistivity of the film layer based on the logarithm of the ratio of the induced EMF value at the initial moment to the induced EMF value at the target moment. The resistivity gradient between the surface and bottom layers of the film is obtained by calculating the ratio of the absolute value of the difference between the surface resistivity and the bottom resistivity to the depth difference between the surface depth and the bottom depth.

[0029] Specifically, carbon black slurry, determined to have reached the percolation state using a four-electrode method, is applied to the PET substrate surface via a precision doctor blade coating head at a constant speed of 19 meters per minute, controlling the wet film thickness to 100 micrometers. This ensures the slurry maintains sufficient conductive network extensibility and responsiveness even in its uncured state. Approximately 6 seconds after the substrate reaches the coating machine exit, a vertically arranged eddy current induction coil array is placed as a non-contact monitoring device. This array consists of 20 planar helical coils, each wound with 0.18 mm diameter copper wire to form a multi-turn structure with an outer diameter of 10 mm and an inner diameter of 5 mm. The center-to-center spacing between the coils is 5 mm, covering the entire film thickness range. An excitation signal with a peak current of 2.5 amps, a frequency of 15 kHz, and a pulse width of 70 microseconds is applied to the coil array via an excitation circuit, forming a pulsed magnetic field with an intensity of approximately 4000 amps per meter. This pulsed magnetic field is instantaneously coupled into the interior of the wet film layer, exciting induced eddy currents at various depths. Because the uniformity of carbon black distribution significantly affects local resistivity, the eddy current decay behavior varies in strength at different depths. Induced electromotive force decay curves were collected for each coil within the range of 0 to 200 microseconds. For example, the coil located at a surface depth of z1 = 12 micrometers had an induced electromotive force of 0.85 V at t = 0 microseconds, which decreased to 0.27 V at t = 50 microseconds; while the coil located at a bottom depth of z2 = 80 micrometers had an initial value of 0.89 V and a target value of 0.64 V. Based on the logarithmic ratio of these two sets of signals, combined with the coil geometry and magnetic field coupling parameters, the surface resistivity was calculated to be 8.1 × 10⁻⁶. 2 Ω·cm, with a bottom resistivity of 6.4 × 10⁻⁶. 2 Ω·cm. The absolute value of the difference between these two resistivities is 1.7 × 10⁻⁶. 2 As a molecule, the depth difference z2 is Ω·cm. Using z1, or 68 micrometers, as the denominator, which is converted to centimeters, we get 0.0068 centimeters, resulting in a resistivity gradient of 2.5 × 10⁻⁶. 3 Euros per centimeter per millimeter.

[0030] In one specific embodiment, the process of applying a pulsed magnetic field to the wet film layer using an eddy current induction coil array and calculating the time-domain decay curves of the induced electromotive force at different depths after the wet film to be tested passes through the coating unit outlet can specifically include the following steps: An array of eddy current induction coils is deployed at the location where the wet film to be tested passes through the coating unit; A pulsed magnetic field is applied to the eddy current induction coil array to penetrate the wet film layer. The conductive carbon black network in the wet film layer generates induced eddy currents, which decay and then generate induced electromotive force signals in each coil in the opposite direction. The induced electromotive force (EMF) signals output by each coil in the eddy current induction coil array are collected, and the amplitude of the induced EMF is calculated based on the induced EMF signals. The relationship between the amplitude of the induced electromotive force at different coil positions and time was plotted as a curve to obtain the time-domain decay curve of the induced electromotive force at different depths.

[0031] Specifically, an eddy current induction coil array is deployed approximately 6 seconds after the coating unit exits along the conveying path. The coil array consists of 20 sets of planar spiral coils arranged vertically along the wet film thickness direction. Each coil has an outer diameter of 10 mm, 100 turns, and 0.18 mm copper wire. The center-to-center spacing between adjacent coils is 5 mm, covering the main conductive area from the surface to the bottom layer of the film. A rectangular current pulse with a frequency of 15 kHz, a pulse width of 70 microseconds, and a peak current of 2.5 A is applied to the coil array via a high-frequency pulse excitation module. This creates a pulsed magnetic field with a maximum magnetic field strength of approximately 4000 A / m at the center of the coil. The pulsed magnetic field penetrates vertically into the still-wet black conductive wet film and excites instantaneous eddy currents within the conductive carbon black network structure. Due to the varying density of carbon black particles at different depths, the induced intensity and decay rate of the eddy currents differ significantly at different depths. As the eddy currents decay, the re-excited eddy currents in the coated film act in reverse on the excitation coils, triggering a corresponding induced electromotive force signal that is fed back to the signal acquisition module. A high-speed data acquisition card was used to synchronously acquire the output of each coil at a sampling frequency of 1MHz, recording the change of induced electromotive force (EMF) over time for 200 microseconds from the pulse start moment. The initial amplitude at 0 microsecond and the amplitudes at target times such as 50 microseconds and 100 microseconds were extracted as feature points for each signal curve. For example, in the coil corresponding to the surface layer at z=15 micrometers, the induced EMF was recorded as 0.91 V at t=0 microseconds and 0.38 V at t=50 microseconds; while in the bottom layer coil at z=75 micrometers, the induced EMF was 0.89 V at t=0 microseconds and 0.66 V at t=50 microseconds, indicating that the eddy current decay rate is faster and the resistivity is higher in the surface layer, while the conductive structure of the bottom layer is denser. By plotting the change of induced EMF amplitude over time for each depth of the coil point by point, a continuous family of time-domain decay curves was formed.

[0032] In one specific embodiment, the process of performing step 103 may specifically include the following steps: When the resistivity gradient exceeds the preset threshold, a bypass circulation loop is led out from the slurry supply pipeline at the front end of the coating head to transport the slurry to the measuring cell of the online laser particle size analyzer for real-time particle size detection. A laser beam is used to irradiate carbon black particles in the slurry through a measuring cell. The scattered light signals generated by particles of different sizes are collected by a multi-angle photodetector array, and the particle size distribution is calculated based on the Mie scattering theory to obtain the volume-weighted average particle size. The carbon black agglomeration index is obtained by calculating the ratio of the volume-weighted average particle size to the initial particle size of the conductive carbon black.

[0033] Specifically, during the coating process, when the eddy current induction coil array located at the exit of the coated film detects a resistivity gradient exceeding a set threshold of 2.8 × 10⁻⁶, 3 When the particle size reaches Ω·cm / mm, the dynamic particle size detection module of the slurry is automatically triggered. A bypass loop is led out from the slurry supply pipeline at the front end of the coating head, and the slurry is introduced into the measurement cell of the laser particle size analyzer at a constant flow rate of 95mL / min via a micro gear pump. The measurement cell adopts a parallel optical path structure with an optical path length of 8mm and is equipped with quartz windows with a transmittance greater than 95% on both sides to ensure optimal signal-to-noise ratio during laser propagation in the slurry. The particle size analyzer is equipped with a helium-neon laser with a wavelength of 632.8nm and an output beam diameter controlled at 12mm. The beam passes through the slurry suspension at a constant intensity, producing multi-angle scattering in the particle group. Carbon black particles of different sizes will produce characteristic scattering intensity distributions at different scattering angles due to the relationship between diameter and wavelength. A high-sensitivity photodetector array covering 0.02° to 135° is configured to synchronously collect the scattered light signals. All signal intensity data are fitted by Mie scattering theory through the built-in inversion algorithm module to reconstruct the volume distribution spectrum of carbon black particles in the coating slurry. In actual measurements, the current particle size distribution ranges from 8 nm to 220 nm, with a volume-weighted average particle size D. 43 The initial particle size of this batch of conductive carbon black is 54.6 nm, while the original initial particle size D is... 10 The carbon black agglomeration index (AI) was calculated to be 22.3 nm before dispersion, indicating significant agglomeration of carbon black in the slurry. If historical samples show an AI value below 1.3, considered an ideal dispersion state, then the agglomeration degree of this sample far exceeds the control limit, requiring further addition of dispersant or an increase in shear rate.

[0034] In one specific embodiment, the process of performing step 104 may specifically include the following steps: The dispersant injection flow rate is obtained by multiplying the square of the carbon black agglomeration index by the exponential function obtained by multiplying the resistivity gradient by the first coefficient, and then multiplying by the second coefficient. Adjust the pumping frequency of the micro pump according to the dispersant injection flow rate so that the dispersant is injected into the front end of the coating head through the injection nozzle; By synchronously adjusting the coating speed or the doctor blade gap to change the wet film thickness, the shear rate of the coating speed and the wet film thickness reaches the set range, thus obtaining the coating slurry.

[0035] Specifically, during the coating process, when the resistivity gradient of the film layer acquired by the eddy current induction array exceeds 2.8 × 10⁻⁶, 3 When the set threshold of Ω·cm / mm is met and the carbon black agglomeration index AI output by the online laser particle size analyzer reaches 2.45, the main control unit immediately invokes the nonlinear response function to perform secondary processing on the AI ​​value and multiplies the film resistivity gradient by the first empirical coefficient 3.2×10. -4 After an exponential transformation, the two results were multiplied and then multiplied by a second empirical coefficient of 0.18 to calculate the current dispersant injection flow rate as 2.82 mg / s. This injection flow rate value was input into the micro-plunger pump control module, which adjusted the pumping frequency to 23 Hz, ensuring a stable injection of the high-concentration ammonium polyacrylate dispersant solution into the main slurry channel at a rate of 2.82 mg / s. The injection operation was performed using a micro-spray nozzle installed upstream of the main channel at a 38° angle to the slurry flow direction. The nozzle orifice diameter was 1.0 mm, forming a fan-shaped distribution area with a radius of approximately 2 cm, spraying the dispersant into the mainstream slurry layer. Rear of the injection point, the slurry passed through a 100 mm long static mixer containing 14 stages of spiral mixing units, ensuring thorough contact between the dispersant and the agglomerated carbon black, achieving efficient molecular layer adsorption. Simultaneously, to ensure the dispersant's action was activated in a suitable rheological environment and to maintain the separation of carbon black particles, the shear rate range was adjusted accordingly. The shear rate is defined as the ratio of coating speed to wet film thickness. Therefore, based on the current film thickness detection value of 92 μm, the controller automatically increases the coating speed from the original set value of 17 m / min to 20 m / min, thus reducing the shear rate from the original approximately 1230 s. -1 Rise to about 1340s -1 This allows it to enter the thixotropic activation range of the dispersant (950-1350s). -1 The shear strength is near the upper limit. Under this shear strength, the polyacrylate molecular chains are fully dechained under the action of the flow field and rapidly adsorbed onto the carbon black surface to form a steric barrier, thereby effectively dismantling newly formed agglomerates and maintaining the dispersion uniformity of the slurry. The state of the coating slurry is optimized in real time through a linkage control mechanism between dispersant flow adjustment and shear environment.

[0036] In one specific embodiment, the process of multiplying the square of the carbon black agglomeration index by the exponential function obtained by multiplying the resistivity gradient by a first coefficient, and then multiplying by a second coefficient to obtain the dispersant injection flow rate can specifically include the following steps: The agglomeration index of carbon black is squared to obtain the squared value of the agglomeration index. The resistivity gradient is multiplied by the first coefficient and then used as the power of the exponential function. The exponential function value of the resistivity gradient is obtained by performing an exponential operation with the natural constant as the base. The dispersant injection flow rate is obtained by multiplying the squared value of the agglomeration index by the value of the resistivity gradient exponential function and then by the second coefficient.

[0037] Specifically, when the real-time measured value of the current carbon black agglomeration index AI is detected to be 2.45, the carbon black agglomeration index is squared, resulting in an agglomeration index squared value of 6.00; simultaneously, the resistivity gradient value obtained from the eddy current induction coil array is 2.6 × 10⁻⁶. 3 Ω·cm / mm, compared with the first empirical coefficient 3.2×10 -4 Multiplying the results yields 0.832, which is used as the power of the exponential function. Using the natural constant as the base, the exponential function value of the resistivity gradient is calculated to be 2.298. Multiplying the two results (6.00 × 2.298) gives a product of 13.788. Multiplying this by the second empirical coefficient of 0.18, the current dispersant injection flow rate is calculated to be 2.48 mg / s. This flow rate value is used as the target setting parameter and sent from the control system to the micro-plunger pump controller, driving the pump to advance the injection stroke at a frequency of approximately 27 Hz, allowing the ammonium polyacrylate dispersant solution to be injected into the main channel of the slurry at a stable rate. The calculation path uses AI=2.45 as a representative threshold point for the severity of agglomeration. Combined with the resistivity gradient feedback value, a nonlinear exponential increase response is formed, initiating compensation intervention in the early stage of uneven carbon black distribution. This, along with subsequent shear rate adjustment, achieves a closed-loop adaptation between the dispersant dosage, shear field strength, and carbon black agglomeration state, thereby maintaining the synchronous construction of slurry structural stability and conductive network continuity.

[0038] In one specific embodiment, the process of performing step 105 may specifically include the following steps: The coating slurry is drawn out from the coating head outlet and transported to the cone-plate measurement system of the rotational rheometer; A two-step shear rate test procedure was performed on the coating slurry. First, a first shear rate was applied until a steady state was reached, and then the first shear viscosity was measured. Then, a second shear rate was applied until a steady state was reached, and then the second shear viscosity was measured. The ratio of the first shear viscosity to the second shear viscosity is calculated to obtain the thixotropic index. The set temperature values ​​of the first, second, and third temperature zones in the drying section are calculated based on the thixotropic index, and then cured to obtain a cured film layer.

[0039] Specifically, during the operation of the coating system, a steady-flow sampling branch is drawn from the coating head outlet pipeline to feed the undried coating slurry into the cone-plate measurement chamber of the rotational rheometer at a rate of 40 mL per minute. The cone-plate system used has a cone angle of 2 degrees, a diameter of 30 mm, and a measurement gap set to 60 micrometers to ensure high sensitivity response under low shear conditions. The applied shear rate is 10 s. -1 The low-shear phase lasted for 30 seconds. After the stress reached a steady state, the first shear viscosity value η1 was collected and measured to be 1280 mPa·s. Then, the speed was immediately switched to 1000 s. -1 The high-shear stage was maintained for another 30 seconds, and after stress stabilization, the second shear viscosity value η2 was recorded as 92 mPa·s. The thixotropic index TI = 13.91 was obtained by ratiocing η1 and η2, indicating that this batch of coating slurry maintains high structural viscosity under low-shear conditions and exhibits rapid structural uncoating and flowability in high-shear fields. The TI value was input into the drying section temperature control algorithm to allocate the three temperature setpoints for the coating film along the longitudinal drying path. Based on a base temperature of 65℃, a thixotropic sensitivity coefficient of 45, a depth decay coefficient of 0.08, and the spacing between the three heating zones z1=2.5m, z2=4.5m, and z3=6.5m, the set temperature T1 for the first temperature zone is calculated to be 94.5℃ using the exponential decay temperature distribution formula. This is used to suppress carbon black migration under structural thixotropic conditions. The set temperature T2 for the second temperature zone is 83.1℃, which promotes a slow decrease in resistivity gradient under moderate heating conditions. The third temperature zone is the rapid curing section, with a set temperature T3 of 106.7℃, used to lock the conductive network and reduce residual solvent to below 1%. The temperature control actuator is an infrared heater array with a power density of 20kW / m². 2 With a response time of less than 3 seconds, it can quickly adjust the temperature of the surface in the temperature zone to obtain a cured film layer.

[0040] In one specific embodiment, the process of calculating the set temperature values ​​of the first temperature zone, the second temperature zone, and the third temperature zone in the drying section based on the thixotropic index and performing a curing process to obtain a cured film layer can specifically include the following steps: Calculate the set temperature values ​​for the first temperature zone, the second temperature zone, and the third temperature zone based on the thixotropic index. The heater in the first temperature zone of the drying section is controlled to reach the set temperature value of the first temperature zone for thixotropic protection treatment. The heater in the second temperature zone of the drying section is controlled to reach the set temperature value of the second temperature zone to reduce the resistivity gradient. The heater in the third temperature zone of the drying section is controlled to reach the set temperature value of the third temperature zone for rapid curing to obtain a cured film layer.

[0041] Specifically, based on the thixotropic index TI=13.91 obtained from the rotational rheometer test of the coating slurry, the thixotropic index is input into the temperature distribution algorithm. Combined with the preset base temperature of 65℃, the thixotropic sensitivity coefficient α=45, the depth decay coefficient β=0.08, and the actual arrangement distances of the three drying zones from the coating head of 2.5 meters, 4.5 meters, and 6.5 meters respectively, the set temperature values ​​for the three temperature zones are calculated sequentially using the exponential decay model. The calculated result for the first temperature zone T1 is 94.5℃, for the second temperature zone T2 it is 83.1℃, and for the third temperature zone T3 it is 106.7℃. The target temperature values ​​are sent to the control modules of each temperature zone, driving the heater array of the first temperature zone at a power density of 20kW / m². 2 Rapid heating to 94.5℃ and maintaining a constant temperature helps preserve the thixotropic high viscosity state, preventing carbon black migration or sagging and protecting the initial structural distribution. The second temperature zone heater control module operates at a set value of 83.1℃. The moderate temperature rise in this stage promotes viscosity reduction and activates the slow movement of carbon black. Combined with the existing shear residual effect, this causes the resistivity gradient to decrease from above 2.8 × 10⁻⁶. 3 The initial value of Ω·cm / mm was gradually reduced to 1.3×10. 3 Below Ω·cm / mm; after the film layer is evenly distributed, the third temperature zone heater rapidly heats up to 106.7℃ and holds for about 12 seconds to achieve rapid solvent evaporation and thermal locking of the conductive network structure, so that the residual solvent content of the film is less than 1%, and a cured film layer is obtained.

[0042] The resistivity gradient measurement method of integrated black ink in the embodiments of the present invention has been described above. The control system in the embodiments of the present invention is described below. Please refer to [link / reference]. Figure 2 One embodiment of the control system in this invention includes: The dispersion module 201 is used to disperse conductive carbon black and fast-drying solvent in a high-speed disperser and monitor the conductivity of the slurry from the initial value to the target value to obtain a percolated carbon black slurry. Coating module 202 is used to coat percolating carbon black slurry onto a substrate, apply a pulsed magnetic field, and calculate the resistivity gradient between the film surface and the substrate. Calculation module 203 is used to calculate the carbon black agglomeration index when the resistivity gradient exceeds a preset threshold. Injection module 204 is used to calculate the dispersant injection flow rate based on the carbon black agglomeration index and resistivity gradient, and control the micro-pump to inject the dispersant so that the shear rate reaches the set range to obtain the coating slurry. The curing module 205 is used to calculate the thixotropic index of the coating slurry and calculate the set temperature values ​​of the first temperature zone, the second temperature zone, and the third temperature zone of the drying section based on the thixotropic index, and obtain a cured film layer through curing treatment.

[0043] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0044] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0045] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An integrated black ink resistivity gradient measurement method, characterized by, include: Conductive carbon black and fast-drying solvent are dispersed in a high-speed disperser, and the conductivity of the slurry is monitored from the initial value to the target value to obtain a percolating carbon black slurry. The percolating carbon black slurry was coated onto the substrate, a pulsed magnetic field was applied, and the resistivity gradient between the film surface and the bottom layer was calculated. When the resistivity gradient exceeds a preset threshold, the carbon black agglomeration index is calculated; The dispersant injection flow rate is calculated based on the carbon black agglomeration index and the resistivity gradient, and the dispersant is injected by a micro-pump to make the shear rate reach the set range, thereby obtaining the coating slurry. The thixotropic index of the coating slurry is calculated, and the set temperature values ​​of the first, second, and third temperature zones of the drying section are calculated based on the thixotropic index. A cured film layer is obtained through curing treatment.

2. The integrated black ink resistivity gradient measurement method of claim 1, wherein, The process of dispersing conductive carbon black and a fast-drying solvent in a high-speed disperser and monitoring the conductivity of the slurry from an initial value to a target value to obtain a percolating carbon black slurry includes: Conductive carbon black is added to a fast-drying solvent and mechanically sheared in a high-speed disperser. Simultaneously, ultrasonic cavitation is applied to break up the secondary agglomerates of carbon black to obtain a primary dispersion slurry. Add ammonium polyacrylate dispersant to the primary dispersion slurry and continue mixing and dispersing to obtain a carbon black slurry containing dispersant; The conductivity of the carbon black slurry containing dispersant was monitored in real time using a four-electrode method. When the conductivity jumped from the initial value to the target value, it was determined that the percolation transition point had been reached and the dispersion process was stopped, thus obtaining the percolation state carbon black slurry.

3. The integrated black ink resistivity gradient measurement method of claim 1, wherein, The process of coating the percolating carbon black slurry onto a substrate, applying a pulsed magnetic field, and calculating the resistivity gradient between the film surface and the substrate includes: The percolating carbon black slurry is coated onto the substrate through a coating head to form a wet film to be tested. After the wet film to be tested passes through the coating unit outlet, an eddy current induction coil array is used to apply a pulsed magnetic field to the wet film layer and calculate the time-domain decay curve of the induced electromotive force at different depth positions. Extract the induced electromotive force value at the initial moment and the induced electromotive force value at the target moment from the induced electromotive force time-domain decay curve. Calculate the surface resistivity of the film surface layer and the bottom resistivity of the film layer based on the logarithm of the ratio of the induced electromotive force value at the initial moment to the induced electromotive force value at the target moment. The resistivity gradient between the surface layer and the bottom layer is obtained by calculating the ratio of the absolute value of the difference between the surface resistivity and the bottom layer resistivity to the depth difference between the surface layer depth and the bottom layer depth.

4. The integrated black ink resistivity gradient measurement method of claim 3, wherein, The process of applying a pulsed magnetic field to the wet film layer using an eddy current induction coil array and calculating the time-domain decay curves of the induced electromotive force at different depths after the wet film passes through the coating unit outlet includes: An array of eddy current induction coils is deployed at the location where the wet film to be tested passes through the coating unit; A pulsed magnetic field is applied to the eddy current induction coil array to penetrate the wet film layer. The conductive carbon black network in the wet film layer generates induced eddy currents, which decay and then generate induced electromotive force signals in each coil in the opposite direction. The induced electromotive force (EMF) signal output by each coil in the eddy current induction coil array is collected, and the amplitude of the induced EMF is calculated based on the induced EMF signal. The change of the amplitude of the induced electromotive force at different coil positions over time is plotted as a curve to obtain the time-domain decay curve of the induced electromotive force at different depth positions.

5. The integrated black ink resistivity gradient measurement method of claim 1, wherein, When the resistivity gradient exceeds a preset threshold, the carbon black agglomeration index is calculated, including: When the resistivity gradient exceeds a preset threshold, a bypass circulation loop is led out from the slurry supply pipeline at the front end of the coating head to transport the slurry to the measuring cell of the online laser particle size analyzer for real-time particle size detection. A laser beam is used to irradiate carbon black particles in the slurry through a measuring cell. The scattered light signals generated by particles of different sizes are collected by a multi-angle photodetector array, and the particle size distribution is calculated based on the Mie scattering theory to obtain the volume-weighted average particle size. The carbon black agglomeration index is obtained by calculating the ratio of the volume-weighted average particle size to the initial particle size of the conductive carbon black.

6. The integrated black ink resistivity gradient measurement method of claim 1, wherein, The step of calculating the dispersant injection flow rate based on the carbon black agglomeration index and the resistivity gradient, and controlling the micro-pump to inject the dispersant to achieve a shear rate within a set range, to obtain the coating slurry, includes: The dispersant injection flow rate is obtained by multiplying the square of the carbon black agglomeration index by the exponential function obtained by multiplying the resistivity gradient by the first coefficient, and then multiplying by the second coefficient. Adjust the pumping frequency of the micro-pump according to the dispersant injection flow rate so that the dispersant is injected into the front end of the coating head through the injection nozzle; By synchronously adjusting the coating speed or the doctor blade gap to change the wet film thickness, the shear rate of the coating speed and the wet film thickness reaches the set range, thus obtaining the coating slurry.

7. The method for measuring the resistivity gradient of integrated black ink according to claim 6, characterized in that, The step of multiplying the square of the carbon black agglomeration index by the exponential function obtained by multiplying the resistivity gradient by a first coefficient, and then multiplying by a second coefficient to obtain the dispersant injection flow rate includes: The agglomeration index of the carbon black is squared to obtain the squared value of the agglomeration index; The resistivity gradient is multiplied by the first coefficient and then used as the power of the exponential function for exponential operation with the natural constant as the base, to obtain the resistivity gradient exponential function value. The dispersant injection flow rate is obtained by multiplying the squared value of the aggregation index with the value of the resistivity gradient exponential function and then multiplying by a second coefficient.

8. The method for measuring the resistivity gradient of integrated black ink according to claim 1, characterized in that, The calculation of the thixotropic index of the coating slurry, and the calculation of the set temperature values ​​for the first, second, and third temperature zones of the drying section based on the thixotropic index, followed by a curing process to obtain a cured film layer, includes: The coating slurry is led out from the coating head outlet and conveyed to the cone-plate measurement system of the rotational rheometer; A two-step shear rate test procedure was performed on the coating slurry. First, a first shear rate was applied until a steady state was reached, and then the first shear viscosity was measured. Then, a second shear rate was applied until a steady state was reached, and then the second shear viscosity was measured. The ratio of the first shear viscosity to the second shear viscosity is calculated to obtain the thixotropic index; The set temperature values ​​of the first temperature zone, the second temperature zone, and the third temperature zone in the drying section are calculated based on the thixotropic index, and then cured to obtain a cured film layer.

9. The method for measuring the resistivity gradient of integrated black ink according to claim 8, characterized in that, The process of calculating the set temperature values ​​of the first, second, and third temperature zones in the drying section based on the thixotropic index and performing a curing treatment to obtain a cured film layer includes: Calculate the set temperature values ​​for the first temperature zone, the second temperature zone, and the third temperature zone based on the thixotropic index. The heater in the first temperature zone of the drying section is controlled to reach the set temperature value of the first temperature zone for thixotropic protection treatment. The heater in the second temperature zone of the drying section is controlled to reach the set temperature value of the second temperature zone to reduce the resistivity gradient. The heater in the third temperature zone of the drying section is controlled to reach the set temperature value of the third temperature zone for rapid curing to obtain a cured film layer.

10. A control system, characterized in that, A method for performing resistivity gradient measurement of integral black ink as described in any one of claims 1-9, comprising: The dispersion module is used to disperse conductive carbon black and fast-drying solvent in a high-speed disperser and monitor the conductivity of the slurry from the initial value to the target value to obtain a percolated carbon black slurry. A coating module is used to coat the percolated carbon black slurry onto a substrate, apply a pulsed magnetic field, and calculate the resistivity gradient between the film surface and the substrate. The calculation module is used to calculate the carbon black agglomeration index when the resistivity gradient exceeds a preset threshold. The injection module is used to calculate the dispersant injection flow rate based on the carbon black agglomeration index and the resistivity gradient, and control the micro-pump to inject the dispersant so that the shear rate reaches a set range to obtain the coating slurry. The curing module is used to calculate the thixotropic index of the coating slurry and, based on the thixotropic index, calculate the set temperature values ​​of the first, second, and third temperature zones of the drying section, and obtain a cured film layer through curing treatment.

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