Definition
Laboratory pilot disperser is a kind of mechanical equipment used for material mixing, dispersion, homogenization and wet grinding. It is often seen as a critical transition device from small laboratory research to pilot production scale-up, suitable for simulating production processes and validating process parameters under controlled conditions. This equipment is not a medical or pharmaceutical special instrument, but is widely used in the experimental research and development and process development stages of many industries such as chemicals, coatings, inks, new energy materials, food science and cosmetics.
Principle
The laboratory pilot disperser mainly realizes the dispersion and mixing of materials through mechanical shear force. Its core working component is usually a high-speed rotating dispersion disc (also known as an impeller). When the dispersion disc rotates at high speed in the container, it will produce a strong radial liquid flow and tangent flow, so that the material is sucked into the dispersion pan area from the bottom of the container and subjected to high shear. In this process, the agglomerated solid particles are broken and fully mixed with the liquid medium to form a uniform and stable dispersion system. Some equipment can also be combined with vacuum, heating or cooling systems to meet specific process conditions. The basic shear rate relationship can be approximately expressed as:
γ ≈ π * D * N / h
where γ represents the shear rate, D is the diameter of the dispersion disc, N is the rotational speed, and h is the gap between the dispersion disc and the bottom of the container. This formula shows that the dispersion intensity can be effectively controlled by adjusting the equipment parameters.
Measurement and evaluation methods
The evaluation of dispersion often relies on the measurement of the performance of the final dispersion system. Common methods include using a particle size analyzer to determine the particle size distribution and D50 value to evaluate the dispersion fineness; The rheological characteristics of the system are measured by a viscometer. Observe or measure the stability of the product, such as by centrifugal settling test, static stratification observation or gloss determination; For colored systems, color uniformity can be evaluated using a colorimeter. These tests refer to relevant industry standards (e.g., ASTM D1210 in coatings, GB/T 6753.1 in chemicals, etc.) to ensure data comparability and process scalability.
Influencing factors
The dispersion effect is affected by multiple factors. In terms of equipment parameters, the shape, diameter, rotational speed of the dispersion disc and its spacing from the bottom of the container are key factors. Process parameters include dispersion time, material dosing sequence and speed, and operating temperature. The material characteristics involve the hardness, initial particle size, and concentration of solid particles, as well as the viscosity and surface tension of liquid media. In addition, the geometry and size of the vessel can also affect the flow field distribution, which in turn affects the mixing efficiency and dispersion effect. In practice, the optimal combination of parameters needs to be determined through system experiments.
Applications
Laboratory pilot dispersers play an important role in several industrial research and development fields. In the coatings and inks industry, it is used for the preparation and stability testing of pigment slurries. In the field of new energy, it participates in the development of mixing and dispersion processes for electrode pastes (such as lithium-ion battery cathode and anode slurries). In the cosmetics industry, it is used for emulsification and homogenization of creams, lotions and other products. In the food industry, it is used in the study of the texture of sauces and condiments. In addition, it is also commonly used in research and development in the fields of nanomaterials, composites, and adhesives to achieve uniform dispersion of nanoparticles in the matrix.
Selection considerations
Choosing the right laboratory pilot disperser requires comprehensive consideration. First, the process requirements need to be defined, including the material handling volume, target viscosity range, desired dispersion fineness, and whether it needs to be accompanied by auxiliary functions such as heating, cooling, or vacuum defoasing. Secondly, pay attention to the technical parameters of the equipment, such as motor power, speed regulation range, speed control accuracy and torque output capacity. The material of the equipment (usually stainless steel) needs to be compatible with the material chemistry and easy to clean. Safety features such as overload protection and mechanical stability cannot be ignored. Finally, the correlation between the equipment and the subsequent production equipment should be considered to ensure that the pilot data can effectively guide large-scale production.