Particle Size Distribution of Titanium Dioxide

Titanium dioxide is present in many aspects of everyday life, its inclusion in commonplace goods often surprising. TiO2's utility in sunscreen -- affecting SPF and opacity -- is better known than its presence as a whitener in skim milk. The particle size of titanium dioxide directly impacts its performance in numerous applications, necessitating the measurement and control of this important property.


Application Note Video: Titanium Dioxide (3 minutes)


Properties Dependent on Particle Size

Most of the numerous useful properties of TiO2 are directly impacted by its particle size distribution. Size affects its final performance in hue & hiding, how it behaves in various formulations via flocculation tendency & viscosity, and its properties which are exploited for niche applications.

A partial list of properties affected by particle size includes:

  • Hue/tint strength
  • Hiding/transparency
  • Gloss/flatting and film appearance
  • Flocculation
  • Viscosity
  • Stability
  • Weather resistance
  • Photocatalytic activity
  • Air/liquid remediation
Titanium dioxide is a key component of paints and primers
Titanium dioxide is a key component of paints and primers

Importance of Monitoring and Controlling Particle Size

The importance of monitoring and controlling particle size is not theoretical; the world’s largest TiO2 manufacturers specify their products by particle size results including the D50 median and geometric standard deviation. Up and down the supply chain, particle size is monitored; most often by laser diffraction technology.

Example particle size result from TiO2 manufacturer
Example particle size result from TiO2 manufacturer

Measurement Considerations

Most uses of titanium dioxide present a tougher dispersion challenge than other common applications. If you wish to measure a wet dispersion, it's recommended to explore the aid of surfactants, admixtures, and ultrasonic energy. If the measurement will be dry, then configure the particle size analyzer for maximum dispersive energy, e.g. small nozzles, high air pressure, feedback control.

DuPont has published a procedure to measure their Ti-Pure product which includes the following:

  • Water dispersant with pyrophosphate anion
  • Kodak Photo-Flo 200 surfactant
  • Significant time to disperse (30+ minutes)

The importance of sample preparation to the measured particle size of TiO2 is apparent in the graph below.

Comparison of titanium dioxide size measurements after 0, 5, and 10 minutes of ultrasonic dispersion
Comparison of titanium dioxide size measurements after 0, 5, and 10 minutes of ultrasonic dispersion

Titanium Dioxide Webinar

This 45 minute webinar covers how the particle size distribution of TiO2 is measured and controlled to change its properties for different applications.

Webinar AP033: Titanium Dioxide and the Importance of Particle Size (Login required).


Dry Particle Size Analysis of Titanium Dioxide

The LA-960 PowderJet accessory provides extremely powerful dry dispersion, enabling the accurate and reproducible measurement of titanium dioxide powders. The graph below shows the PowderJet's ability to reproducibly distinguish a 12 nanometer difference two different TiO2 powders.

LA-960 PowderJet distinguishes a 12 nanometer difference in the median sizes of two titanium dioxide powders
LA-960 PowderJet distinguishes a 12 nanometer difference in the median sizes of two titanium dioxide powders

The PowderJet achieves this remarkable resolution because it has been designed for maximum dispersion. It accelerates compressed air to subsonic speeds using a venturi nozzle. For more information, visit the PowderJet page.


Nanoparticle Dispersion Stability

Certain TiO2 applications require stability analysis via zeta potential measurement. The SZ-100 Nanoparticle Analyzer can measure both the size and zeta potential for nanoparticle dispersions.


Upstream Titanium Dioxide Processing

Roughly 50% of all titanium dioxide is produced from ilmenite ore. The size and shape of the ore impacts processing efficiency, i.e. yield, re-work rate. The CAMSIZER Dynamic Image Analyzer is used to measure the particle size and shape of ilmenite and provide intelligent sieve matching to maintain historic specifications.

Overlay of multiple CAMSIZER measurements and sieve specification for ilmenite ore
Overlay of multiple CAMSIZER measurements and sieve specification for ilmenite ore

How Laser Diffraction Works

The LA-Series of analyzers uses laser diffraction technology to provide the fastest, easiest to use particle size results for paper applications. The results are extremely reproducible across multiple operators, multiple units, and multiple locations. 

Webinar TE010: Introduction to Laser Diffraction (Login required).


Summary of Benefits

The particle size of titanium dioxide plays a crucial role in nearly all of its applications. Particle size analysis is a highly valued measurement all the way from upstream processing of titanium ore chunks to nanoparticle dispersions. HORIBA's array of measurement technologies and decades of application expertise ensure a solution to even the most demanding titanium dioxide applications.


Particle Analyzers for Titanium Dioxide Applications

LA-960

The LA-960 uses Mie Scattering (laser diffraction) to measure particle size of suspensions or dry powders. The speed and ease-of-use of this technique makes it the popular choice for most applications.

LA 300

The LA-300 uses Mie Scattering (laser diffraction) to measure particle size of suspensions. The speed and ease-of-use of this technique makes it the most popular for many applications.

CAMSIZER Dynamic Image Analyzer

HORIBA's CAMSIZER features dynamic image analysis to provide rapid and precise particle size and particle shape distributions for dry powders and bulk material in the size range from 20µm to 30mm.

SZ-100 Nanopartica Series Instruments

Industry's widest range and highest precision measurement instrument for Nanoparticle characterization.