Definition
A coating power disperser is a mixing and dispersing equipment used in the preparation of coatings, inks, pigments, and other similar fluids or slurries. Its core function is to apply strong shear, impact and turbulence to the material through the high-speed rotating dispersion disc, so as to evenly disperse the powdery solid particles into the liquid medium, and realize the depolymerization and refinement of agglomerated particles, so as to reduce the particle size, improve the distribution uniformity and stabilize the system.
Principle
The working principle of the coating power disperser is mainly based on the shear and turbulence effects in fluid mechanics. The equipment usually consists of a motor, a drive shaft, a dispersion disc and a container. The motor drives the drive shaft to rotate at high speed, driving the movement of the dispersion disc mounted at the end of the shaft. Dispersion discs are usually toothed disc structures, and when they rotate at high speed, the serrations on the edge of the disc generate strong shear force on the material. At the same time, the dispersed coil material forms a high-speed vortex, generating a huge centrifugal force, so that the material is sucked from the bottom of the container to the dispersion plate area and ejected to the periphery, forming a circular flow. In this process, the agglomerated solid particles are broken and dispersed by the combined effects of fluid shear, interparticle collision and impact force. The dispersion effect can be related to the shear rate, which is related to the linear velocity of the dispersion disc and the fluid characteristics.
Measurement and evaluation methods
The evaluation of the effect of a paint force disperser usually relies on the performance testing of the final slurry or coating. Key measurement parameters include fineness, viscosity, and stability. The fineness is usually measured by a scraper fineness meter, and the degree of dispersion is determined by observing the appearance of particles in the slurry in the trench according to the national standard GB/T 1724 or equivalent international standard. For viscosity measurement, a rotational viscometer is used to monitor changes in rheological properties according to GB/T 9269 and other standards to evaluate the dispersion uniformity. In addition, the long-term stability of the dispersion system can be evaluated by observing the sedimentation, stratification, or flocculation of the stored sample. For R&D or process control, laser particle size analyzers are sometimes used to determine particle size distribution more accurately.
Influencing factors
The dispersion effect is affected by multiple factors. In terms of equipment parameters, the diameter, tooth shape design and linear speed of the dispersion disc are decisive factors, and the linear speed directly affects the shear force. The process parameters include dispersion time, processing temperature, and the order and method of feeding materials. The material properties cover the hardness, initial particle size, and concentration of solid particles, as well as the viscosity and chemical properties of liquid media. The geometry and size of the container, as well as the relative position of the dispersion disc in the container (e.g., the height from the bottom), will affect the flow field shape and material circulation efficiency, thereby playing a role in the dispersion effect. These factors need to be coordinated and optimized according to the specific recipe in practice.
Applications
Coating power dispersers are widely used in industrial fields where solid particles need to be dispersed uniformly and stably in the liquid continuous phase. In the coating manufacturing industry, it is used for the dispersion of pigments and fillers. In the ink industry, it is used for the preparation of color pastes. In addition, the equipment plays a key role in laboratory research and development and industrial production in the fields of dyes, pesticide preparations, cosmetics, electronic pastes, ceramic glazes and nanomaterial preparation. It handles a wide range of viscosities for materials and is suitable for a wide range of fluid systems from low to high viscosity.
Selection considerations
Choosing the right coating power disperser requires comprehensive consideration. First, it is necessary to clarify the characteristics of the material being processed, such as the expected processing volume, initial viscosity range, solids content, and final required fineness requirements. Determine the capacity and power configuration of the machine according to the scale of production. The form and material of the dispersion disc should match the corrosiveness and wear of the material. The equipment should have reliable speed regulation functions to adapt to the speed requirements of different stages. Safety measures, easy cleaning and maintenance design, and energy consumption levels are also important selection points. It is recommended to refer to the relevant national standards for machinery safety and industry application experience, and take into account the convenience of operation and the economy of long-term operation under the premise of meeting the process goals.