Why particle sizing matters for paints and coatings

If you’ve ever had to give a wall a fresh coat of paint, you may have noticed that brands compete by emphasizing that their high-gloss paints are made with the finest pigments. In fact, they are also referring to the particle size of their pigments: low-gloss and flat paints can include coarser particles, while high-gloss paints require very fine pigment particles. Indeed, the particle size distributions affect both the appearance and performance of colloids such as those used in ornamental and functional paints and coatings.

Why does particle size matter?

Battery electrodes, for example, are typically manufactured by coating a metal foil substrate with a multi-component slurry partly made up of electrode particles. The size distribution of these particles influences the slurry’s ease of application and determines the thickness, uniformity, packing density, and porosity of the resulting coat. This determines, in turn, key battery performance parameters such as recharge time.

Particle size also influences how light interacts with a coating, affecting its opacity and tint. However, it is also crucial in the powder coating process, as optimal size distributions reduce the heat and time needed for the curing process. This ensures a more consistent finish and reduces energy consumption, an important sustainability benefit.

Liquid spray coatings also benefit from particle size analysis, as a better understanding of spray paint droplet size helps optimize the coating process parameters. The spray plume, for instance, can be adjusted accordingly to maximize the amount of paint transferred onto the substrate.

The challenges of particle sizing

Especially in production environments, effective particle sizing faces similar challenges in all three applications:

• The analysis must be done rapidly and with a high throughput to avoid becoming a bottleneck.
•  The materials used in battery and powder coating production often vary in quality and origin – and therefore particle size – so a wide measurement range is necessary.
•  The analysis must be straightforward so that operators on the production floor or the laboratory can achieve reliable results with minimal training and effort.

To overcome these challenges, many researchers and manufacturers use laser diffraction, which is highly flexible and very well adapted to this context.

Why laser diffraction is an effective particle sizing technique

Traditional methods for particle sizing in battery manufacturing include sieving, sedimentation, and microscopy. These techniques can be slow. Instead, laser diffraction provides considerably faster and more reproducible particle size measurements.

Laser diffraction measures the angular variation in light intensity as a laser beam passes through a particulate sample, using the Mie theory of light scattering to calculate particle sizes. Unlike sieving, it measures the entire distribution of particle sizes, enabling much more accurate control and monitoring of pigment particles, spray droplets, powder coating particles, and electrode slurry particles.

Modern laser diffraction systems are also highly automated, offer high throughput with minimal manual input, and provide a very wide measurement range that runs from 0.01 to 3,500μm. In addition to laboratory-based laser diffraction systems, Malvern Panalytical provides online process systems that deliver real-time monitoring of particle size for automated process control.

Our laser diffraction solutions

Whether it’s analyzing dry samples such as cathode precursor and electrode materials, or wet samples like electrode slurries and spray droplets, Malvern Panalytical can provide a laser diffraction solution for many applications:

• The Mastersizer 3000+ enables you to measure the size distributions of particles in suspensions, emulsions, and powders in the wide range of 0.01-3,500 µm. Its user-friendly design and artificial intelligence-powered software ensure every user can obtain rapid and accurate particle size distributions.  
• The Spraytec system enables size distribution measurements of spray particles and droplets in the 0.1-2,000 µm range. Measurements are carried out in real-time and in situ to assess the evolution of spray plumes, and its analysis software makes it easy to recognize any inconsistencies or changes.
• The Insitec system enables size distribution measurements of powders, emulsions, sprays, and slurries in the 0.1-2,500 µm range. Its online measurement capabilities allow for cost-effective process control in real time, and it delivers analysis every few seconds for quantities ranging from milligrams to hundreds of tons of material per hour.

Our particle solutions can also be boosted to provide complementary particle insights. For example, the Hydro Insight accessory for the Mastersizer 3000+ provides particle shape characterization alongside the Mastersizer’s size analysis. With instruments available for multiple applications, we provide valuable materials insights in a variety of production processes – bringing more value to your business through better data.

If you’d like to find out more about laser diffraction and whether it’s the solution to your particle-sizing challenges, contact our experts today.