White Masterbatch: TiO2 Content, Hiding Power, and Cost Optimization

TiO2: The Core of White Masterbatch

Titanium dioxide (TiO2) is the most widely used white pigment in the plastics industry, valued for its exceptional brightness, opacity, and chemical stability. White masterbatch concentrates TiO2 in a carrier resin at levels from 40% to 75%, with the concentration directly determining hiding power, whiteness, cost, and processability. Understanding the relationship between TiO2 content and performance is essential for optimizing both quality and cost.

TiO2 Crystal Structure: Rutile vs Anatase

TiO2 exists in two primary crystal forms used in plastics:

Always choose rutile TiO2 for plastic applications. Anatase has photocatalytic activity that accelerates polymer degradation under UV light. All MHK Color white masterbatch uses rutile-grade TiO2.

TiO2 Content Levels Compared

40% TiO2: Tinting and Light White

At 40% TiO2 loading, the masterbatch is primarily used for tinting applications—adding a slight white tone to colored or natural resin—or for products where full opacity is not required. It is the easiest to process due to the high carrier resin ratio and is the most cost-effective per kg. Typical applications: tinted containers, light white injection moldings, color matching base white.

60% TiO2: The Standard Workhorse

The 60% grade is the industry standard for general white masterbatch, offering a good balance of opacity, whiteness, processability, and cost. It is the default choice for most white injection-molded products, including containers, caps, household items, and white pipe. At 1%–5% loading, it achieves a whiteness index above 90 and good hiding power for most applications.

Typical uses: Shopping bags, bottle caps, white HDPE pipe, household containers, consumer goods.

75% TiO2: Maximum Performance

At 75% TiO2, the masterbatch delivers maximum hiding power and whiteness at the lowest addition rates (0.5%–3%). This grade is essential for thin-gauge products where high opacity is needed at low loading, including:

• Thin films (15–50 μm) where carrier dilution must be minimized
• Blow-molded bottles requiring uniform white opacity
• Premium white consumer products with high whiteness requirements
• Pigment masterbatch for let-down applications

Trade-off: The high TiO2 loading increases melt viscosity, requiring higher processing temperatures and screw torque. Processing windows are narrower than lower-TiO2 grades.

Surface Treatment: Inorganic vs Organic Coating

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

For outdoor applications, choose TiO2 with zirconia coating for enhanced weather resistance. For indoor applications, standard alumina-silica coating is sufficient.

Hiding Power and Cost Optimization

Hiding power (opacity) depends on both TiO2 content and product thickness. The relationship is not linear—doubling TiO2 does not double opacity:

Cost optimization rule: For thick products (>1mm), use 60% TiO2 at low loading. For thin products (<0.5mm), use 75% TiO2 at moderate loading. This minimizes both TiO2 usage and carrier dilution.

Common Defects and Solutions

Conclusion

Selecting the right TiO2 content for white masterbatch depends on the product thickness, opacity requirement, processing method, and cost target. For most applications, 60% TiO2 at 2%–4% loading is the optimal balance. For thin films and maximum opacity, 75% TiO2 at low loading provides superior performance. Always use rutile-grade TiO2 with appropriate surface treatment for your application's weather resistance requirements.