Slurry dispersion and mixing system (for batteries and electronic materials)

In low bulk density powders and fine powders, issues such as "unstable supply," "pulsation," and "bridging without falling" frequently occur. Particularly with CNTs, carbon black, and flake powders, the particles tend to entangle easily and have low flowability, making stable quantitative supply difficult with conventional powder feeding methods. When powder supply becomes unstable, instantaneous concentration fluctuations occur, significantly affecting the dispersion quality, viscosity, and conductivity in subsequent processes. In practice, even problems that appear to be "poor dispersion" often have their causes on the powder supply side. Moreover, in low bulk density powders, bridging, rat-holing, and supply pulsations due to air entrapment are likely to occur within the hopper, and simply relying on feeder capacity may not resolve these issues. To achieve stable supply, it is crucial to design the entire process, including hopper design, supply methods, transport conditions, and feeding methods, according to the characteristics of the powder. Our company offers a solid-liquid mixing process that includes quantitative supply using loss-in-weight feeders and integration with inline dispersion devices. By designing the entire process from powder supply to dispersion as a cohesive unit, we support the establishment of stable manufacturing conditions even for high-performance materials.

In the dispersion process of high-viscosity slurries, issues such as "not being dispersed despite being mixed" and "remaining clumps" occur. The main cause of these problems is that the increase in viscosity reduces fluidity, preventing dispersion energy from being evenly transmitted throughout the system. Generally, dispersion breaks apart agglomerated particles through shear force, but in a high-viscosity state, the flow becomes localized, leading to differences between areas experiencing shear and those that do not. As a result, undispersed areas and agglomerates remain, causing variations in particle size distribution and quality issues. Furthermore, the higher the viscosity, the weaker the circulation within the equipment, making it difficult for particles to pass uniformly through the processing area, which also decreases reproducibility. In batch processing, variations in residence time and mixing state become particularly pronounced, making it easier for lot differences to occur. To achieve stable dispersion in high-viscosity systems, not only shear enhancement but also flow design and ensuring circulation are important. By simultaneously controlling flow and shear, as in inline continuous processing, uniform and highly reproducible dispersion can be achieved. Additionally, the wettability of the powder and the method of introduction during the initial dispersion are also crucial; if the initial dispersion is insufficient, the subsequent breaking efficiency decreases.

In the dispersion of high solid content slurries, viscosity increases and fluidity decreases, making it prone to poor dispersion and variability. The movement of particles is restricted, making it difficult for aggregates to break apart, and it is not uncommon for undispersed areas to remain. Additionally, poor wetting during powder addition and the formation of localized high concentration areas can lead to the occurrence of clumps, which is another challenge. These issues may not be completely resolved even with strong shear applied in subsequent processes. What is important under such high solid content conditions is to efficiently transmit dispersion energy and standardize the processing conditions for each particle. However, in batch processing, variations in flow and residence time can lead to differences in the dispersion state. On the other hand, in inline continuous processing, uniform shear can be applied to particles within the flow, allowing for efficient transmission of dispersion energy even under high viscosity and high solid content conditions. This results in a uniform dispersion state for each particle, achieving stable quality. In the dispersion of high solid content slurries, it is crucial not only to apply strong shear but also to design the process considering flow and processing conditions. Inline processing is one effective method to address these challenges.

In the dispersion process of high solid content slurries, problems such as "too high viscosity to mix" and "unable to break down agglomerates" occur. The main cause of these issues is the increased frequency of particle contact, which strengthens the cohesive forces. As the solid content concentration increases, the distance between particles decreases, leading to interference between particles that reduces fluidity and prevents sufficient dispersion energy from being transmitted. Additionally, the crowding of particles restricts flow and makes shear localized, resulting in the persistence of undispersed areas and agglomerates. Furthermore, in a high solid content state, the increase in viscosity also leads to poor circulation and stagnation, causing variability in the dispersion state within the process. Particularly in batch processing, mixing inconsistencies and differences in processing history directly translate into quality differences, making it difficult to ensure reproducibility. To achieve stable dispersion under high solid content conditions, it is important not only to increase shear force but also to consider dispersion design that takes into account inter-particle interactions, as well as process design that simultaneously controls flow and shear. By establishing a mechanism like inline continuous processing, where particles pass through the processing area under constant conditions, uniform and highly reproducible dispersion can be achieved even at high solid contents.