What is ultrafine powder？
Ultra-fine powder refers to the tiny particles generated during the process of crushing, grading or conveying of powder coatings due to excessive external force for fine grinding.
The cause of ultrafine powder:
- The particle size distribution of the raw materials is too wide
- Inappropriate control of the extrusion process
- Wear and tear of crushing and screening equipment
- Secondary refinement during the process of pneumatic conveying and storage
- Disassociation of electrostatic aggregates
The effects of ultrafine powder:
- The flour usage rate has decreased
- Low utilization rate of recycled powder
- It is prone to cause surface defects such as pinholes, blistering and pitting
- Reducing the mechanical properties of the coating and the uniformity of curing
- Low liquidity, prone to absorbing moisture and forming lumps
Solution for ultrafine powder:
- Raw materials and pre-treatment: Select resin and fillers with uniform particle size and adequate drying, and ensure thorough mixing
- Extrusion process: Set the temperature and screw rotation speed reasonably to avoid excessive melting or shearing
- Shredding and classification: Optimize the parameters of the mill and classifier, and adopt multi-stage classification technology when necessary
- Transportation and Storage: Reduce the flow velocity of the transported gas, use low-maintenance pipelines, and add a small amount of flow aids
- Recycling: The ultrafine powder separated out is reused in proportion or processed into dedicated powder. Online particle size monitoring is used to achieve closed-loop control
In conclusion, the generation of ultrafine powder is the result of multiple factors combined. By optimizing raw materials, processes, equipment and recycling management, it is possible to effectively reduce ultrafine powder and enhance coating performance and economic benefits
