Thin film breakthrough

Citation

(1998), "Thin film breakthrough", Pigment & Resin Technology, Vol. 27 No. 2. https://doi.org/10.1108/prt.1998.12927baf.001

Thin film breakthrough

Thin film breakthrough

A Malvern Instruments' Mastersizer particle characterization system has played a crucial role in thin film powder coating research undertaken by the Courtaulds Coatings' Particle Management Technology Group. The recently launched Courtaulds Interpon XTR ­ the first of a new generation of thin films ­ was developed using the group's patented "particle management technology", which depends on the Mastersizer system for its success.

The Particle Management Technology Group focuses its research on thin film powder coatings which match the appearance and durability of thicker films, but at a significantly reduced cost. Market demand for thinner films is a key driver within the coatings industry, but achieving a commercially acceptable thin film has proved to be a complex technological challenge.

The main barrier to success lies not within the coating formulation nor the manufacturing process, but in the behaviour of individual particles themselves. Using thick film formulations for thinner applications can give an unsatisfactory finish of poor opacity due to the large average size of the particles. However, when average particle size is reduced increased cohesion results, causing surging and spitting during application.

In order to meet this challenge, the Courtaulds Group intensively studied the physical properties of powders, with the aim of influencing and managing small particles and their electrostatic behaviour within the powder flow. A crucial development was the installation of the Malvern Mastersizer system, which enabled the team to measure particles of 10 microns and below quickly, accurately and repeatedly.

Using laser diffraction technology, the Mastersizer measures over a wide scattering angle enabling it to measure the smallest particles. The use of Mie theory, accepted as the most accurate analysis across all size ranges, wavelengths and scattering angles, is essential at these small sizes (< 25µm). Full Mie solution is needed if samples contain transparent or small particles, and is absolutely essential when a significant proportion of material is below 25 microns.

The first fruit of the group's research, Interpon XTR, has been heralded as a breakthrough in thin film development, offering a reduction of up to 30 per cent in final film weight, and applied coating cost reductions of 10 to 20 per cent. The formulation also meets exacting standards for flow, transportation and sprayability. As a result, Malvern Mastersizer systems are in operation in Courtaulds' plants worldwide to ensure international production quality is both consistent and directly comparable. In a further development, an agreement between the two companies ensures stocks of spares are held specifically for Courtaulds.

Further details are available from Malvern Instruments Ltd. Tel: +44 (0) 1684 892465; Fax: +44 (0) 1684 892789; janr@malvern.co.uk