Pigment pastes

Pigment masterbatches are polymer-based additives in the form of pellets, which are mixed into the raw polymer to colour it. In comparison to powdered pigments, pastes and liquid additives, these special compounds increase process stability and are readily processed.

Pigment masterbatches are produced by mixing coloured pigments and/or chemicals with raw polymers such as FPM, VMQ or FVMQ. The mixtures are then strained in an extruder with a filtration unit and optionally pelletised, using a strand pelletiser for example. Finally, the desired pellet size is selected using a grading screen.

The finished masterbatch is packed into plastic sacks or foil-lined drums and then delivered to the rubber-processing industry.

Pigment masterbatches are the ideal way of colouring silicone and fluorosilicone mixes or fluorocarbon compounds. For most rubber processing methods in-plant colouring is possible, which is more economical. Standard RAL colours are cost-effective and ensure consistency of colour in the final product. UV stabilisers, antioxidants, flame retardants, antistatics, lubricants and many other substances can also be added to pigment masterbatches if required.

Pigment masterbatches bring the world of rubber to life

Without colour, the world would be a dull and monotonous place. The same is true of products in the rubber-processing industry, since in their unmodified state the colour spectrum of the compounds that are used is somewhat limited. However, much more important than an attractive appearance is the fact that in many cases products are coloured for technical reasons. For instance, colouring can help to identify the finished item, while adding selected pigments can improve the hot-air resistance of the vulcanisates in the range above 200°C. Both of these possibilities can be achieved with Radosil pigment masterbatches for silicone and fluorosilicone mixes or with the masterbatches that are available for EPDM, NBR or FPM compounds. In principle, pigment masterbatches are suitable for all polymer classes.

RADO pigment masterbatches are polymer-based additives with a high pigment concentration in the form of pellets or pastes. They offer a clean and simple way of introducing an almost infinite variety of colours into silicone and fluorosilicone mixes as well as mixes based on other polymers.

Pigment masterbatch production – creating a multitude of colours

By the 1960s the rubber and rubber-processing industry was already producing many popular products, but there were limits to the choice of colours available. White, black, grey and a standard blue, red, green and yellow were the only real options. That all changed at the start of the 1970s. Vivid orange telephones, pastel-coloured toys, bright kitchen utensils – without pigment masterbatches, these would probably still not exist even now.

Masterbatches are often produced using internal mixers or single- or twin-screw extruders, which homogenise rubber, fillers, additives and the necessary pigments to form compounds for onward processing. All pigment batches are subsequently filtered using special screens to obtain the desired physical form. This gives RADO pigment masterbatches their unique purity. The polymer that the processor wishes to colour – FPM, VMQ or FVMQ, as well as EPDM, NBR and others – is generally used as the carrier polymer. Custom colours can be specified and sampled in close consultation with the user. The colour settings are recorded in the quality assurance lab using a sophisticated colorimetry system, so they can be reproduced at any time.

Advantages of colouring with a pigment masterbatch

Pigment masterbatches consist of concentrated, very finely ground pigments, which are dissolved in a polymer carrier. They are the most cost-effective means of colouring rubber compounds and can be used even with small production quantities. Depending on the chosen carrier, the same masterbatch can be used to colour different mixes.

The biggest advantage of coloured pellets over powdered pigments, pastes and liquid colours is that they allow for precision processing. They produce absolutely true-colour, homogeneous results, even in long-running production processes. State-of-the-art mixing methods enable a masterbatch to be reproduced exactly, ensuring there are no colour deviations in the finished products. Another advantage is that the masterbatch pellets do not spill or create dust and require no complex storage arrangements or health and safety provisions. The work involved in cleaning the mixers is dramatically reduced.

Applications for pigment masterbatches

Pigment masterbatch preparations can be used to colour almost any type of rubber compound. By incorporating additives into the pigment masterbatch, compounds and the products made from them can not only be made to look attractive but can also be given useful functional properties. The following can be added, for example:

  • Plasticisers
  • Flame retardants
  • UV stabilisers
  • Lubricants
  • Antistatics
  • Mould release agents
  • Nucleating agents
  • Heat stabilisers
  • Processing aids

You can use our contact form to request a selection of the available pigment masterbatches at any time.

Rolf Müller
How can we help you?


Tab 1
Tab 2
Tab 3