White Masterbatch TiO2 Grades: Rutile vs Anatase and Loading Optimization

The Role of Titanium Dioxide in White Masterbatch

Titanium dioxide (TiO2) is the most widely used white pigment in the plastics industry, delivering exceptional opacity, whiteness, and hiding power. In white masterbatch, TiO2 is typically loaded at 40–75%, and its grade selection — crystal form, particle size, and surface treatment — has a decisive impact on the optical performance and processing behavior of the finished product.

Global TiO2 production is split between the chloride and sulfate processes, both producing the two crystal forms: rutile and anatase. For plastics, rutile is the dominant choice due to its superior optical and weathering properties.

Rutile vs Anatase

Rutile is the standard for plastics because its higher refractive index gives better opacity, and its lower photocatalytic activity prevents polymer degradation (chalking and embrittlement) under UV exposure. Anatase is occasionally used for indoor applications where cost is paramount and weathering is not a concern.

Surface Treatments

Commercial TiO2 pigments are surface-treated to improve dispersion and reduce photocatalytic activity. Common treatments include:

• Alumina (Al2O3) coating: Reduces photoactivity, improves weatherability and dispersion.
• Silica (SiO2) coating: Further reduces photoactivity for demanding outdoor applications.
• Organic (polyol/siloxane) treatment: Improves wetting and dispersion in non-polar polymers like PE and PP.

For polyolefins, alumina-organic treated rutile is the standard. For outdoor PVC and engineering plastics, alumina-silica treated rutile provides maximum durability.

TiO2 Loading and Opacity

White masterbatch TiO2 content typically ranges from 40% to 75%:

• 40–50% TiO2: General-purpose white masterbatch for standard opacity.
• 60–70% TiO2: High-opacity grades for thin films and lightweight containers.
• 75% TiO2: Maximum hiding power for demanding applications, but requires careful dispersion.

Below a certain TiO2 concentration, opacity drops sharply because particles crowd too closely and scatter light inefficiently. This "crowding effect" means simply adding more TiO2 has diminishing returns — good dispersion and the right particle spacing matter as much as total loading.

Choosing the Right White Masterbatch

1. Indoor general-purpose: 40–50% rutile, alumina-organic treated, standard dispersion.
2. Outdoor durable: 60% rutile, alumina-silica treated, weatherable grade.
3. Thin film / high opacity: 70–75% rutile, high dispersion, low gel formation.
4. Food contact: Rutile with FDA/EU 10/2011 compliant surface treatment.

Conclusion

TiO2 grade selection — crystal form, surface treatment, and loading — determines the whiteness, opacity, and durability of white masterbatch. MHK Color offers white masterbatch from 40% to 75% TiO2 using rutile-grade pigment with application-matched surface treatments. Tell us your base resin, part thickness, and whether the product is for indoor or outdoor use, and we will recommend the optimal TiO2 grade and loading.