Particle Shape Analysis of Toner Powder for Laser Printers
Toner powder, essential for laser printers and photocopiers, is a composite of carbon and various polymers. The specific polymer used varies by manufacturer, leading to diverse toner formulations tailored for different devices. A critical characteristic in these formulations is the granule size, which directly influences print quality and efficiency.
Evolution of Toner Particle Size
Historically, toner particles averaged 14–16 micrometers in size. To enhance image resolution, manufacturers reduced particle sizes to approximately 8–10 micrometers, achieving 600 dots per inch (dpi) resolution. Maintaining a consistent particle size distribution is vital for optimal printer performance and high-quality output.
Importance of Particle Shape and Size Analysis
While particle size is crucial, the shape of toner particles also significantly impacts printing performance. Spherical particles ensure smooth flow and uniform application, reducing wear on printer components and enhancing print clarity. Therefore, analyzing both particle size and shape is essential for quality control in toner production.
Advanced Imaging Techniques for Toner Analysis
Utilizing advanced imaging techniques, such as those provided by the Pi Sentinel PRO instrument, allows for precise measurement of particle size and shape. In a recent analysis, approximately 150,000 toner particles were examined, revealing a near-normal distribution centered around 10 micrometers. The smallest particles measured were about 2 micrometers. This high-resolution analysis ensures that both the primary toner grains and any larger beads are accurately characterized, contributing to improved toner formulation and printer performance.
According to Wikipedia, “Originally, the particle size of toners averaged 14–16 micrometers or greater. To improve image resolution, particle size was reduced, eventually reaching about 8–10 micrometers for 600 dots per inch resolution. Toner manufacturers maintain a quality control standard for particle size distribution in order to produce a powder suitable for use in their printers.”
Toner grains are small, with a low quantity of larger beads in occurrence, and are almost spherical. As it is legitimately possible to presuppose universal sphericity, it is enough to implement Equivalent Circular Area as the predominant size measure, alongside Circularity and Smoothness, which yield further characterization.
Results
A particle count of 150,000 using a Particle Insight instrument, generates extremely smooth distribution graphs. The ECA histogram is remarkably close to normal, with low skewness. The smallest size observed was 2 microns, while the center measured around 10 microns.
Both a Number Weighted as well as a Volume Weighted histogram are shown below. The Volume weighted histogram would be the closes to what a size-only analyzer would report such as laser diffraction. Volume weighted data important to view because the agglomerates can be identified easily. Also Smoothness and Circularity are monitored to monitor and identify outlier particles.
Additional analysis was done of numerous toner particles. The goal was to identify agglomerates. Below are results of the various toner particles analyzed.
Conclusion
Comprehensive particle shape and size analysis of toner powder is imperative for the advancement of laser printing technology. Employing sophisticated imaging methods enables manufacturers to maintain stringent quality control, ensuring consistent and high-quality print outputs across various devices.