TiO2 for Powder Coatings
TGIC and TGIC-free polyester powder coatings — TiO2 must withstand 200°C extrusion + 180–200°C cure.
Powder coatings are solvent-free paint systems applied as dry powder and cured by heat (typically 180–200°C for 10–20 min). They are the dominant coating for steel furniture, appliances, architectural aluminum, and many automotive components. The dominant chemistries are TGIC-polyester (now phasing out for HSE reasons), TGIC-free polyester, epoxy-polyester hybrid, and epoxy.
For TiO2 selection, powder coating demands high thermal stability: the pigment goes through twin-screw extrusion at 100–130°C, then cure at 180–200°C. The TiO2 surface treatment must not degrade at these temperatures (which would cause yellowing). SEMITI 706 and 826D have proven track records in powder coating.
Recommended SEMITI grades
Performance requirements
| Thermal stability (200°C / 20 min) | Δb* < 1.5 |
| Tinting strength after extrusion | No measurable loss vs starting powder |
| Outdoor durability (architectural) | QUV 2000 hr > 70% gloss retention |
| Adhesion (ISO 2409) | Class 0–1 cross-hatch |
Dosage guidance
Dispersion / processing notes
Powder coatings are compounded in twin-screw extruders (Buss-Kneader or modern co-rotating twin-screw), with TiO2 fed at the throat or side-fed at zone 4–5. Output strand is cooled, ground, and classified to 30–50 μm finished powder. No traditional dispersion step.
Formulation tips
- →SEMITI 706 for premium architectural / appliance powder; SEMITI 826D for high-durability outdoor applications
- →TGIC-free polyester is the modern standard — uses HAA (hydroxyalkylamide) crosslinker, compatible with SEMITI 706/826D
- →For metallic powder coatings, use aluminum flake + 8–12% TiO2 + colored pigments
- →Test cure performance with the specific TiO2 batch — minor batch-to-batch variation can shift cure-onset temperature by 5–10°C
Common pitfalls
Failure modes we've seen in customer trials — worth checking before scale-up.
- ×Using sulfate rutile in powder coating — yellowing during 200°C cure visible immediately
- ×Inadequate degassing in extruder — leads to pinhole defects in cured film
- ×Mixing chloride and sulfate TiO2 — color stability lost
Common questions
Why is powder coating TiO2 loading higher than liquid?+
Is SEMITI 706 acceptable for architectural aluminum powder coating?+
Pair with matting agent for powder coatings
TiO2 provides hiding power; silica matting agent provides gloss control. Both products are typically required in the same matte/eggshell formulation. Our sister brand GMATT (matting-agents.com) supplies the matched silica matting agent.
Need help picking a grade for powder coatings?
Send us your reference grade, formulation type, or competitor TDS. We'll respond with the SEMITI match + sample within 48 hours.