Measuring particle size and shape in print toners

Malvern Instruments has developed Sysmex FPIA-3000, an automated particle size and shape analyser for the wet chemistry method of producing print toners.

With the development of wet chemistry methods for the production of print toners, information about particle shape as well as particle size is becoming increasingly important.

The Sysmex FPIA-3000 automated particle size and shape analyser from Malvern Instruments is widely used in the industry to provide valuable data essential for optimising both production and the products themselves.

Conventionally toners have been produced using a pulverization process.

Particle size can be controlled to within +/- 0.3 - 0.5 mm for material with an average size of 8 mm: size distribution can also be controlled.

Newer processes based on suspension or emulsion polymerization have introduced a requirement for much closer control of particle shape and material properties, as well as particle size.

The fully automated Sysmex FPIA-3000 can measure particles in the range 0.8 to 300 microns and delivers both particle size and shape information.

Using a CCD camera, the system produces images of each particle and provides a scattergram of shape index versus particle size in just 2.5 minutes.

Samples pass through a sheath flow cell that transforms the particle suspension into a narrow or flat flow, ensuring that the largest area of the particle is oriented towards the camera and that all particles are in focus.

The CCD camera captures 60 images every second and these are analysed in real time.

Numerical evaluation of particle shape is derived from measurement of the area of the particle.

A number of shape factors are calculated including circularity, aspect ratio and circle equivalent diameter.

All measurements are stored, as are the particle images, and the system provides comprehensive data analysis and display parameters, together with a variety of options for data output.

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