TiO2 for Coil Coatings
Pre-painted steel and aluminum coil for roofing, siding, appliances — durable rutile for 20+ year outdoor service.
Coil coating is the process of continuously painting metal coil (typically steel or aluminum) on dedicated coating lines. The coated coil is then sold to fabricators who form it into roofing panels, siding, garage doors, appliances, and ACE (Architectural, Construction, Equipment) products.
Coil coating represents the most demanding outdoor service for paint — typical warranty periods are 15–25 years on architectural cladding and 10–15 years on residential roofing. The paint film is very thin (15–25 μm) and applied at high line speed (typically 80–200 m/min), requiring the paint to be perfectly formulated for the application process.
The dominant coatings chemistries are polyester (cost-optimized), silicone-polyester (mid-tier durability), and PVDF / fluoropolymer (premium). SEMITI 826D (matched to Tronox CR-826) is the workhorse grade across all three. SEMITI 706 is acceptable for tier-2 polyester systems.
Recommended SEMITI grades
Performance requirements
| QUV gloss retention | > 80% at 5000 hr (PVDF systems) |
| Florida exposure (10 yr) | ΔE < 2, no chalking grade 2 |
| T-bend formability | 0T bend without paint cracking |
| Reverse impact | 180 in-lb passes ASTM D2794 |
| Salt spray (B117) | 1500 hr no field corrosion |
Dosage guidance
Dispersion / processing notes
Coil coating paint is supplied to the line in liquid form, then applied by roller coater. Dispersion is done at the paint plant in high-energy bead mills to Hegman 7+. Tight rheology control is required for clean application at 100+ m/min line speed.
Formulation tips
- →SEMITI 826D is the default for PVDF Kynar 500 / Hylar 5000 systems
- →For premium PVDF metallic colors (architectural cladding), use SEMITI 826D base + aluminum flake + iron oxide as the colorist's palette
- →Backer coats can use lower-cost SEMITI 902 — they're not weather-exposed
- →Line speed > 150 m/min requires verification of TiO2 PSD compatibility — narrow PSD prevents roller pickup defects
Common pitfalls
Failure modes we've seen in customer trials — worth checking before scale-up.
- ×Substituting sulfate rutile for chloride in coil coating — chalking and gloss loss within 5 years
- ×Insufficient pigment dispersion at high line speed — leads to streaks and color non-uniformity
- ×Using lower-durability rutile (SEMITI 706 or 902) in PVDF premium cladding — system underperforms its warranty period
Common questions
What's the difference between polyester and PVDF coil coatings?+
Why is coil coating gloss retention spec higher than other outdoor applications?+
Pair with matting agent for coil 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 coil coatings?
Send us your reference grade, formulation type, or competitor TDS. We'll respond with the SEMITI match + sample within 48 hours.