Paints and coatings

Characterization is important across the whole paints and coatings supply chain, whether for developing, manufacturing, and qualifying raw materials for use in a coating formulation, or formulating components together to create a robust product with the correct performance characteristics and quality attributes. Examples include developing novel polymeric binders to enhance surface protection, optimizing the particle size distribution for the application of interest, and ensuring coating dispersions are stable under the appropriate conditions.

Particle size

Particle size  analysis is critical to the performance of any product containing particulate material, whether in a dispersion, suspension, powder, or spray. The primary particle sizing tool is laser diffraction , with the Mastersizer considered the industry standard for a range of applications, with dry and wet dispersion capabilities and a wide dynamic range. It can be used to monitor powder milling processes, check particle size distribution in a final product, or as a formulation tool for developing and researching new products. Malvern Panalytical also offers a laser diffraction product called Spraytec specifically for the analysis of sprays, and an on-line analyzer called Insitec , which can be integrated into a process for real-time particle sizing and automated control. For the accurate analysis of nanoparticle dispersions (< 1 µm), the Zetasizer Advance range may be more appropriate. This uses dynamic light scattering to measure dispersed particles to below 1nm in diameter and can also be used to look at surfactant aggregation and smaller latex particles.

Dispersion stability

As well as measuring the particle size distribution of dispersion, the Zetasizer Advance range can measure the zeta potential of a dispersion, which can influence product stability. Zeta potential can also be used to probe interactions within a formulation and can also be measured on a surface.

Particle shape

In addition to particle size, Malvern Panalytical provides solutions for particle shape analysis. The Morphologi 4 automated imaging system determines the size and shape of irregular particles by analyzing tens of thousands of particles in the sample and classifying them accordingly. Morphologi 4-ID also combines automated imaging and Raman spectroscopy to provide particle-specific chemical information.

Elemental analysis

Malvern Panalytical’s primary tool for elemental analysis is X-ray fluorescence (XRF), which is used in the analysis and manufacture of pigments and additives for paints and coatings. It can also be used to determine the concentration of a given element or compound in a coating such as titanium dioxide or lead. XRF solutions include Zetium and Epsilon 4. 

Polymer analysis

Many coatings have a polymeric component that functions as a film former or binder in a formulation. The polymer’s macromolecular structure directly affects the film properties, performance, and rheological behavior. Gel permeation chromatography (GPC) is a common tool for determining the molecular weight of macromolecules and, when combined with advanced detection, can provide additional information related to molecular size and structure, such as branching. The OMNISEC GPC system combines GPC and advanced detection and can be used to analyze low-molecular-weight materials such as oligomers, photo-curable resins, and epoxy resins as well as high-molecular-weight polymer systems.

Bulk and surface microstructure

Many pigments used in coatings are multi-phase crystalline or semi-crystalline materials, and it can be important when manufacturing such materials that these powders have the correct structure and phase. For example, TiO₂ can have different properties depending on the relative amounts of rutile and anatase and their crystallite sizes. X-ray diffraction (XRD) systems such as Aeris and Empyrean can be used to determine key microstructural characteristics such as the phase composition and crystallite size of metals and inorganic materials commonly used in paints. The Empyrean multipurpose diffractometer can also be used to study the structure and residual stresses of thin films, making it ideal for looking at the properties of the coating itself.