Definition
An automatic disperser is a laboratory sample preparation equipment used to evenly disperse solid particles in liquid media and form a stable suspension system. It realizes rapid wetting, dispersion and homogenization of samples through the combination of mechanical and fluid mechanics, and is widely used in R&D and quality control links in coatings, inks, nanomaterials, cosmetics and food and other industries.
Principle
The core working principle of the automatic disperser is based on the shear and impact forces generated by high-speed rotation. The equipment is typically driven by a motor that drives the spindle to rotate the dispersion disc or rotor at high speed in the sample container. When the dispersion disc rotates, its edge throws the material towards the container wall at high speed, and at the same time, a strong shear and turbulence zone is formed near the blade. This process can be broken down into several key functions: first, the negative pressure generated by the dispersion disc draws in the powder and preliminarily wetts it; secondly, the high-speed shear force breaks the agglomeration between particles; Finally, continuous circulation ensures that the dispersion system is uniform between macro and micro. The dispersion effect is closely related to the energy density of the input and can be conceptually described by the following relations:
E ∝ ρ N³ d⁵ t / V
where E represents the dispersion energy, ρ is the fluid density, N is the rotational speed, d is the diameter of the dispersion disk, t is the processing time, and V is the processing volume. This formula qualitatively illustrates the influence trend of each parameter on the dispersion effect.
Measurement and evaluation methods
The evaluation of dispersion effects requires a combination of process monitoring and endpoint analysis. Process monitoring typically includes real-time measurements of speed, torque, and temperature, which indirectly reflect the state of dispersion. Endpoint analysis requires sampling for offline detection, and common methods include particle size analysis (e.g., laser diffraction or dynamic light scattering to determine particle size distribution), microscopy (optical or electron microscopy to check agglomeration), and stability testing (e.g., static layering observation, zeta potential measurement). In practice, it is often necessary to integrate multiple methods to comprehensively evaluate the fineness, uniformity and stability of the dispersion system.
Influencing factors
The dispersion effect is affected by multiple factors, which can be mainly divided into three categories: equipment parameters, process parameters and material properties. The equipment parameters include the type, diameter and geometry of the dispersion disc, and its design directly affects the flow field and shear strength. The process parameters cover rotational speed, processing time, temperature control and feeding sequence, where the matching of rotational speed and time plays a key role in the final dispersion quality. The material properties involve the particle size, surface energy, and hydrophilicity of the powder, as well as the viscosity, density and chemical composition of the liquid phase. These factors are interrelated, such as higher viscosity systems may require higher shear forces or longer processing times.
Applications
Automatic dispersers play an important role in many industrial and scientific fields. In the coating and ink industry, it is used to evenly disperse pigments and fillers in resin bases, which directly affects the coloring and hiding power of products. In nanomaterial preparation, it helps to achieve the deagglomeration and stable dispersion of nanoparticles in the matrix. In the field of cosmetics, it is used to prepare stabilizing systems such as creams and lotions. In addition, it plays a similar role in the food industry (e.g. chocolate slurry), battery slurry preparation, and ceramic slurry processing, with the core goal of obtaining homogeneous, stable multiphase mixtures.
Selection considerations
Choosing the right automatic disperser requires a systematic approach to actual needs. First, the characteristics of the treated material should be clarified, such as the expected processing volume, initial particle size, final fineness requirements and system viscosity range. Secondly, consider the equipment functions, including the power and speed control range of the motor, whether it has torque display and program control functions, the accuracy and stability of the lifting system, and whether it is equipped with cooling or heating kits to control the process temperature. In addition, safety, design for easy cleaning and maintenance, and compliance with relevant industry standards (e.g., electrical safety standards, machinery safety standards) are also important considerations. It is recommended to verify the suitability of the equipment for a specific process through sample testing.