Particle Analysers for Pigment Sizing

An industrial pigment is an organic or synthetic mineral used to tint a material and alter its spectral absorption characteristics. Essentially, they change the colour of a product via selective wavelength absorption or transmittance. These desirable chromatic properties are ideal for use in manufacturing, visual arts, and engineering commercial products such as inks, paints, cosmetics, and food colorants. Organic ochre and iron oxides have been used for pigmentation since the prehistoric era, but modern pigments are subject to stringent measuring requirements to ensure they are suitable for distinct applications.

This blog post will explore the use of particle analysers for pigment sizing, and the importance of particle size and distribution for industrial and commercial colorants.

The Importance of Pigment Size

Particle size and distribution are fundamental properties to the performance of industrial pigments in liquid, solid, and amorphous states. They determine the depth of colour achieved via pigmentation due to a property known as tinctorial strength. Tint strength refers to a pigment’s ability to impart colour to a solid surface or to another liquid media such as a dye. Pigments of decreased particle diameters are usually associated with increased tinctorial strengths up to a maximum point at which particles become translucent to incident light. Narrowing the particle distribution can also improve the absorptive properties of the pigment.

Laser diffraction particle analysers are among the most common instruments used to measure the particle size and distribution of pigments. This is achieved by introducing an incident laser light to a pigment sample and electronically analysing the scattered light to determine the arrangement of particles. The primary drawback of this technology is that it is limited by reduced sensitivity at sub-micron levels.

PIDS Particle Analysers for Pigment Sizing

Polarisation Intensity Differential Scattering (PIDS) is a patented detection system for reliably measuring particles down to nanometers. It achieves this by sequentially illuminating the pigment with three distinct wavelengths of light that are first vertically, then horizontally polarised. The system then measures variations in the intensity and the vector of scattered signals at different angles and compares them against data acquired by the primary laser. This displays a precise, continuous size distribution at sub-micron levels.

PIDS particle analysers represent the most robust pigment measurement technology currently available, with multi-frequency wavelength analysis and full implementation of the Mie theory for accurate characterisation of pigments with particles as small as 10 nanometers. The LS 13320 XR is uniquely suited for analysis of the real refractive indices and the imaginary components of small particles. It is also prepared to measure individual particle dimensions for non-spherical pigments and determine the aspect ratios of colorants with complex morphologies.

Each of these properties is critical for ensuring the optimal optical properties of pigment products and to ensure that they are mechanically-suited for specific delivery systems. PIDS particle analysers are routinely used to assess the tinctorial strength of pigments and ensure their applicability for distinct printing techniques.

Particle Analysers from Meritics

Meritics supplies cutting-edge particle analysers with innovative solutions to meet established and emerging industry challenges. The LS 13320 XR is one of our highest resolution particle analysers and is conceived as a comprehensive tool for a wide range of research and development applications.

If you would like any more information about our particle analysers, please do not hesitate to contact us.