Definition
Shear emulsification dispersion machine is a mechanical equipment used to efficiently mix, refine, disperse and emulsify two or more immiscible liquids and solid particles with liquids. Its core function is to generate strong shear, impact and turbulence through high mechanical energy input, so that the size of the dispersed phase particles or droplets in the material is significantly reduced, and it is evenly and stably distributed in the continuous phase, so as to form a uniform and stable dispersion system or emulsification system. The equipment is widely used in many industrial and scientific research fields such as chemical, food, coatings, new energy materials, daily chemicals and nanomaterial preparation.
Principle
The working principle of the shear emulsification disperser is mainly based on the high-strength mechanical shear force and hydraulic shear force generated by the rotor-stator structure. The core working part of the equipment typically consists of a rotor rotating at high speed and a stationary stator, maintaining precise tiny gaps between the two. As the rotor rotates at high speed, the material is sucked into the rotor-stator area from the bottom or side of the equipment. In the narrow gap, the material is subjected to strong mechanical shear; At the same time, the rotor blades throw the material towards the inner wall of the stator at high speed, creating further impact and collision. The material is then injected at high speed through the precise gaps in the stator, subjecting it to intense hydraulic shear and hole effects. This cyclic compound action can quickly break the agglomerated particles or large droplets, and realize the fine dispersion and emulsification of materials. The dispersion effect is closely related to the rotor line speed, stator gap geometry, action time and material properties.
Measurement and evaluation methods
The measurement and evaluation of the treatment effect of the shear emulsification dispersion machine mainly revolves around the uniformity and stability of the final dispersion system. Commonly used methods include particle size analysis, which uses a laser particle size analyzer to measure the particle size distribution of particles or droplets, and characterizes them with characteristic particle size parameters such as D50 and D90. System stability can be assessed by standing and observing stratification time, centrifugation acceleration experiments, or analyzing changes in backscattered light flux using multiple light scatterometers. For high-viscosity systems, rheological tests such as measuring viscosity-shear rate curves can also reflect the dispersion state. In laboratory research, the morphology and distribution of dispersed phases are sometimes directly observed with the help of a microscope (light or electron microscope). These measurement data provide a key basis for process optimization and equipment selection.
Influencing factors
The final treatment effect of the shear emulsification dispersion machine is affected by multiple factors. In terms of equipment parameters, the rotor speed and linear speed are the key, and higher speeds usually produce stronger shear forces, but energy consumption and heat generation need to be considered. The clearance size between the stator and the rotor and the shape of the opening of the stator head (such as round holes, long holes, and mesh) directly affect the shear strength and flow field characteristics. In the process parameters, the processing time, processing temperature (cooling control required), and the order and method of feeding materials need to be considered. The properties of the material itself are more fundamental, including the viscosity of the continuous phase and the dispersed phase, the interfacial tension between the two phases, the hardness and initial particle size of the solid particles, and the type and amount of emulsifier or dispersant in the formulation. These factors need to be systematically matched and optimized in practical applications.
Applications
The application of shear emulsifiers covers a wide range of industrial and scientific research fields that require fine mixing. In the coatings and inks industry, it is used for the dispersion of pigments and fillers to ensure uniform color and system stability. In the daily chemical industry, it is the key equipment for the production of creams, lotions, shampoos, toothpastes and other products to achieve uniform emulsification of oils and actives. In the food industry, it is used to make salad dressings, dressings, dairy products and juices for homogeneous emulsification. In the field of new energy materials, it participates in the stirring and dispersion of electrode pastes (such as lithium-ion battery cathode and anode slurries). In addition, it also plays an important role in the preparation of nanomaterials, adhesives, polymer composites, and pesticide preparations, and is a common process equipment to achieve uniform product performance and high quality.
Equipment selection considerations
Choosing the right shear emulsifier is a systematic project that requires a comprehensive evaluation of specific needs. First, the characteristics of the treated material should be clarified, such as viscosity range, solids content, particle hardness, sensitivity to shear heat, and target particle size requirements. Determine equipment specifications and forms based on throughput and production mode (batch or continuous). The type of working head (rotor-stator combination) of the equipment needs to be matched to the material characteristics, for example, high-viscosity materials may require a specially designed toothed structure. The motor power and speed range should provide sufficient shear energy. The equipment material (such as stainless steel) needs to meet the corrosive requirements of the material and the production cleanliness standards. In addition, the scalability of the equipment (e.g. whether it is easy to connect to the online decentralization system), ease of cleaning, ease of maintenance, and safety features are also important practical considerations. It is recommended to obtain key process parameters through small or pilot test verification before large-scale selection.