Powder coating is an environmentally friendly, solid powder coating applied electrostatically and cured at high temperatures to form a durable, decorative film. Achieving high-quality coating results requires careful application technique, defect prevention, and proper storage to avoid caking.
1. Powder Coating Application Process
Edge Coverage
Add 0.5%–1.0% of an anti-flow agent such as polyethylene wax, polyvinyl butyral, or silica to ensure an even coating on edges and corners and prevent shrinkage or buildup.
Preventing Lumps
Lumps are caused by powder clumping, poor atomization, or metallic pigment buildup. Adding finely divided aluminum oxide (Al₂O₃), silica (SiO₂), or an anti-caking agent can improve flow.
Surface Defects
Raised particles may be caused by unmelted inorganic matter or gelled organic matter, while pits are often caused by resin incompatibility or contamination. Select compatible raw materials and maintain a clean spraying environment.
Pigment Coverage Tips
Black: 0.5%-1% carbon black + 0.2% phthalocyanine blue (for tint)
White: 25% titanium dioxide + ultramarine blue or permanent violet
Red: Increase resin content and add titanium dioxide and yellow pigment for brightness.
2. Key Application Considerations
Environment: Well-ventilated, ≤35°C, no open flames or direct sunlight
Powder Inspection: Ensure powder is dry and free of lumps before spraying.
Operator Safety: Wear protective clothing; avoid prolonged skin contact; if skin contact occurs, wash with soap.
Static Grounding: Fully ground spray equipment to prevent static electricity and ensure coating adhesion.
3. Anti-Agglomeration Strategies
Formulation Optimization
Reduce the content of low glass transition temperature (Tg) polymers, such as leveling agents, to maintain a higher Tg in the powder system.
Resin Improvement
Select alcohols or acids that increase Tg during polyester resin production.
Adding an Anti-Caking Agent
Add 0.2%–0.5% nano-silica or nano-alumina to prevent particle adhesion and improve flowability, especially in high-humidity, high-temperature environments.
Product Control
Throughly cool the crushed chip material before grinding. Reduce feed rate, increase airflow, and use cooling air intake to control grinding temperature. Forced cooling before grinding is more effective than air conditioning alone.
4. Conclusion
Successful powder coating application and agglomeration prevention require a holistic approach—optimizing the formulation, controlling the environment, and implementing strict production standards. Following these methods ensures a smooth, durable, and defect-free coating.
