Technical FAQ

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Here you find answers to the most common technical questions about TiO₂ pigments, powder analysis, and formulation optimization.
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Section 1: TiO₂ Pigments – General Questions

What is a "drop-in" TiO₂ pigment and when is it preferred?

A "drop-in" pigment is immediately ready for use in existing formulations without modification. Advantages: Immediate availability and ease of use Cost-effective solution Challenges: Difficult to replace if a customer uses a highly specialized, customized TiO₂ benchmark.

When do customers seek an alternative, better-performing TiO₂ pigment?

Customers look for alternatives if performance improvements are needed, including: Higher brightness and tint strength Improved opacity (hiding power) Enhanced gloss and dispersibility Optimized undertone and color stability Better processing, handling, and dosing behavior

Why is particle size distribution important for TiO₂ pigment performance?

A high refractive index alone does not guarantee excellent pigment properties. An optimized particle size distribution ensures effective light scattering, maximizing hiding power and gloss. Well-balanced TiO₂ pigments combine a high refractive index with a particle size distribution centered around 300 nm for optimal optical performance.

How does TiO₂ pigment scattering power influence optical coating and plastic performance?

The high scattering power of TiO₂ pigments is the key to their optical performance. It results from a combination of high refractive index and optimized particle size distribution. High scattering power ensures strong hiding power in coatings, high opacity in plastics, and enhanced brightness in formulations without unwanted color shift.

What is the optimal particle size for TiO₂ pigments to achieve maximum scattering efficiency?

The optimal particle size for maximum scattering efficiency in TiO₂ pigments is around 310 nm when targeting visible light (550 nm wavelength). This size maximizes light scattering due to the relationship between refractive index contrast and particle dimensions. Maintaining this particle size distribution is critical for achieving the highest hiding power and gloss in coatings and plastics.

What distinguishes TiO₂ pigments from colored and black pigments?

TiO₂ pigments reflect nearly all visible light due to their high scattering power and optimal particle size, resulting in a bright white appearance. In contrast, colored pigments reflect only certain wavelengths, while black pigments absorb nearly all light.

How do TiO₂ pigments from the sulfate and chloride processes differ?

TiO₂ pigments produced by the chloride process (CP) generally exhibit higher scattering efficiency and better optical performance compared to pigments from the sulfate process (SP). This is due to more precise control over particle size distribution and typically more spherical primary particles in CP pigments.

Why can SP and CP TiO₂ pigments achieve comparable hiding power despite different scattering efficiencies?

Although sulfate-process (SP) TiO₂ pigments generally have lower scattering efficiency compared to chloride-process (CP) pigments, their slightly higher absorption levels (indicated by a slight yellow tint) compensate for this. As a result, both pigment types can achieve comparable hiding power in coatings and plastics.

What is an inorganic surface treatment of TiO₂ pigments?

Inorganic surface treatments of TiO2-pigments consist of deliberately deposited layers based on aluminum, silicon, zirconium, or phosphorus compounds. These coatings specifically modify the physico-chemical properties of titanium dioxide pigments, such as scattering behavior, weather resistance, and dispersibility.

What is the purpose of an inorganic surface treatment for TiO₂ pigments?

Inorganic surface treatments are applied to titanium dioxide pigments to modify and optimize their physico-chemical properties for specific applications, including coatings, plastics, and inks.

Which properties are affected by inorganic surface treatment of TiO₂ pigments?

Gloss Brightness Color tone Weathering stability Opacity (hiding power) Gloss haze Chalking resistance Viscosity Tinting strength Dispersibility Processing behavior Specific surface properties Gloss retention

What is the objective of inorganic surface treatments on TiO₂ pigments?

The primary goal of inorganic surface treatments is to adapt TiO2 pigment properties to meet specific customer and application requirements, improving performance in coatings, plastics, and inks.

How does Al₂O₃ surface treatment affect TiO₂ pigments?

Aluminum oxide (Al₂O₃) post-treatment adjusts the TiO2-pigment’s surface charge and enhances matrix compatibility. Key improvements include: Better dispersibility Improved filtration behavior during processing Optimized flow and handling characteristics Reduced viscosity increase during grinding (especially in coatings) Improved lacing behavior in film production Side effect: Possible increase in viscosity Enhanced lacing effects in polymer applications

What are the effects of SiO₂ surface treatment on TiO₂ pigments?

Silicon dioxide (SiO₂) coating further improves matrix compatibility and significantly enhances weathering properties. Additional effects: Improved gloss retention in TiO2-pigmented systems Reduced complexity in processing operations Side effect: Slight modification of gloss properties, depending on the system

What improvements does ZrO₂ surface treatment provide?

Zirconium dioxide (ZrO₂) treatment significantly increases the weathering resistance of TiO₂ pigments, making them highly durable in demanding exterior applications. Side effect: Increased abrasiveness in pigmented systems, which can affect processing, particularly in printing inks.