澁谷工業 Company Overview

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 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 dispersion engineering, stable quality cannot be achieved solely based on the performance of the equipment. What is important is the overall design of the process, taking into account material properties and process conditions. This is referred to as dispersion process design. Dispersion quality is determined not only by the strength of shear but also by multiple factors such as flow state, residence time, and method of input. If these conditions are not properly designed, localized agglomeration or variation can occur, making it difficult to maintain stable quality. For example, poor wetting during powder input or the occurrence of stagnant areas due to flow bias can lead to clumping or dispersion issues. Additionally, even if the shear energy is sufficient, if it does not act uniformly on all particles, differences in dispersion state will arise. Therefore, in dispersion processes, it is crucial to design "flow," "shear," and "processing time" as an integrated system. This allows for all particles to receive the same dispersion history, achieving uniform and highly reproducible dispersion quality. In particular, inline continuous processing has the advantage of maintaining consistent conditions within the flow, making it easier to ensure reproducibility in process design. Dispersion process design is a key concept for stabilizing quality and successfully scaling up.