Titanium dioxide (TiO₂) is widely used in coatings, plastics, and inks for its excellent opacity and brightness. However, common challenges like poor dispersion and yellowing can compromise product quality. This guide analyzes the root causes and provides actionable solutions to optimize TiO₂ performance.
1. Solving Poor Dispersion Issues
Root Causes:
- Inadequate surface treatment: Untreated TiO₂ particles tend to agglomerate.
- Incompatible dispersion media: Incorrect solvents or resins reduce wetting efficiency.
- High viscosity systems: Thick formulations prevent proper particle separation.
Solutions:
✔ Use Surface-Treated TiO₂
- Opt for grades with silica/alumina coatings (e.g., Kronos 2160) to improve compatibility.
✔ Optimize Dispersion Process
- Premix TiO₂ with solvents before adding resins (e.g., use high-speed dispersers at 2000–3000 rpm).
- Add dispersing agents (e.g., polyphosphates) at 0.5–2% of TiO₂ weight.
✔ Adjust Formulation
- Reduce viscosity with co-solvents (e.g., propylene glycol) for water-based systems.
- For plastics, use coupling agents (e.g., silanes) to enhance TiO₂-polymer bonding.
2. Preventing Yellowing of TiO₂
Root Causes:
- UV degradation: Anatase TiO₂ (vs. rutile) is prone to photocatalytic reactions.
- High-temperature processing: Overheating during extrusion/painting causes oxidation.
- Impurities: Iron (Fe³⁺) or sulfur residues accelerate discoloration.
Solutions:
✔ Select Rutile TiO₂
- Rutile grades (e.g., Chemours R-706) offer superior UV resistance vs. anatase.
✔ Add Stabilizers
- UV absorbers: Hindered amine light stabilizers (HALS) at 1–3%.
- Antioxidants: Phosphites (e.g., Irgafos 168) for high-temperature applications.
✔ Control Processing Conditions
- Limit extrusion temperatures to <220°C for plastics.
- For coatings, avoid prolonged drying at >120°C.
✔ Use High-Purity TiO₂
- Choose chloride-process TiO₂ (Fe content <50 ppm) for critical applications.
3. Case Study: Overcoming Dispersion & Yellowing
A paint manufacturer reduced TiO₂ settling by 40% and eliminated yellowing by:
- Switching to a silica-coated rutile grade.
- Adding 0.8% polyacrylate dispersant.
- Incorporating 1.5% benzotriazole UV absorber.
4. Pro Tips for Formulators
Post time: Aug-08-2025