Dispersibility vs distribution

The dispersion process and how to achieve optimum dispersion is the key to success in colouration for concentrate manufacturers such as Prisma Colour.

It is often the case that confusion surrounds the understanding of what dispersion actually means when referring to colour and it is a term used when distribution is really what is meant.

Basic considerations for dispersion.

Pigments (organic or inorganic) are soluble and must be dispersed using technical processes. They are made up of solid, primary particles and are crystaline in nature.

Polymer Soluble Dyes however, do not need to be dispersed as they dissolve and are soluble into the media in which they will in colour. In this case, dyes need melting and distributing effectively in the host polymer/carrier system. As a result, these are usually transparent in the application when processed correctly.

Pigments scatter light in the host substrate and therefore are not as transparent as dyes.

Undispersed / poorly dispersed pigment under a microscope.

Prisma Colour are experts in the field of dispersion and providing top quality solid and liquid dispersions for the plastics, rubber, aqueous and silicone dispersion fields.

Technically, there are four stages or steps to the dispersion process:

      1) Breaking down the particles

      2) Wetting of the particles

      3) Distribution of the particles

      4) Stabilisation of the melt or liquid to be a usable form.

Some of the effects of poor dispersion can be:

      – Streaks of colour, rather than uniform colour development

      – Surface defects on lay down of paints

      – Fluctuations in colour intensity and deviations in shade

      – Presence of visible pigment agglomerates as colour specks

      – Clogging of injection moulding gates or screen packs in the extruder

      – Tearing of the bubble during blown film extrusion

      – Filter value high: breakage of fibres, monofilaments and tapes

      – Printing problems due to surface defects

      – Reduced mechanical strength of film and fibres.

Have you seen these issues with your supply?

Contact us now to enhance your formulations and further improve your liquid dispersion requirements!