COATING TECHNOLOGY
The new technique enables colour to be added within the printing process
TRUE COLOURS P
A new technique to coat plastic particles for 3D printing overcomes material and colour palette limitations
owder Bed Fusion (PBF) or laser sintering is one of the most common commercial 3D printing techniques,
where a layer of free-flowing polymer powder is deposited and melted into a desired shape layer- by-layer. Polyamide-12 (PA-12) is a strong plastic that is often used in during this process to print complex and detailed parts used in automotive and aerospace applications. However, designers have thus far
been limited to colour options at the printing stage, with grey or white
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powders requiring colour to be added afterwards in an additional step. Until now, that is, as a team of researchers from the University of Nottingham’s School of Chemistry and Faculty of Engineering have recently developed a method to coat plastic polymer particles to add colour and anti- mould and fungal properties to the printing process.
COATING PARTICLES Eduards Krumins, PhD Student in the School of Chemistry, explains how the technique works: “The coating process was designed in such a way that it
would be one-step, sustainable, and scalable. The key to the process is the use of supercritical CO2 as a solvent. This solvent has unique properties which allows us to coat each PA- 12 particle in a uniform manner by adding a monomer and an initiator along with the PA-12 particles into our reaction vessel. Then, we achieve reaction conditions which are 3,000psi and 65ºC, at this point the polymer starts to form and simultaneously coats each particle. After the reaction is finished, we simply remove the supercritical CO2 and collect the polymeric particulate powder.”
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