Special pigments for the coloring of plastics

Colortherm® fulfills all requirements for sustainable and high quality coloring

Today numerous commodity articles are made from plastic. The pigments used for coloring plastics must satisfy a number of exacting technical and quality requirements. Given the usually short dwell times and relatively low shear forces in the processing equipment, the pigments must have good dispersibility. They must be easy to break down and distribute to reach their final tinting strength quickly. They must also have high thermal stability, and their light fastness and weather stability must be adequate for the intended application. They should not migrate.

The Colortherm® product range has been particularly developed for plastic coloring and fulfills these high requirements. Most of the Colortherm grades are available in a micronized form which contains reduced agglomerates. Colortherm® iron oxide pigments include Yellows, Reds, Browns, and Blacks with a wide variety of additional shades in between.

Normal iron oxide yellow pigments possess limited heat stability. Colortherm® Yellow 10 and Colortherm® Yellow 20 are subjected to an inorganic after treatment, the latter with hydrophobic properties, to increase their heat stability. Both grades are stable up to 260 °C and are therefore suitable for HDPE (High Density Polyethylene) and PS (Polystyrene) formulations.
Colortherm® Yellow 30, a stabilized zinc ferrite, is stable up to 300 °C and can be used in all engineering plastics.

Compared to the limited heat stability of normal iron oxide yellows, the Colortherm® pigments can be used without restrictions.

The coloring of PVC requires good stabilization and careful pre-testing should be undertaken for demanding applications. 

Apart from special yellow pigments, LANXESS has also developed exceptionally heat-stable brown and black pigments. The products Colortherm® 645 T (brown pigment) and Colortherm® 303 T (black pigment) are both manganese ferrites with outstanding heat stability of over 500 °C.

Colortherm® Green pigments, which are based on chromium oxide pigments, have excellent resistance properties – heat stability, migration resistance, light fastness and weather stability. They are suitable for coloring almost any type of plastic. When dispersing these pigments, their relatively high inherent hardness should be borne in mind. This can be significant if high-speed mixers are used, for example when mixing PVC powders or working with a high-speed extruder. In these cases, metal elements may be subject to more abrasion due to the hardness of the pigment.

Chromium Oxide Green pigments can be mixed with stable brilliant yellow pigments to produce the saturated greens required by, for example, the household appliance industry. Chromium Oxide Green pigments are also used in the technical sector, e.g. for coloring engineering plastics for machine components.

Colortherm® Green GN-M is often used in PVC pastes, as used for coating truck tarpaulins or floor coverings, because the colored paste can be produced in a dissolver.

Colortherm® Green pigments contain nearly no chrome (VI) and can also be used for the coloring of food packaging.

All Colortherm® pigments are specially pre-tested in PVC to meet the high demands of the plastics industry with regard to product conformity.

The Global Competence Center Specialties will gladly answer individual customer inquiries with respect to this field of application or provide further information about LANXESS pigments.