A substantially non-infrared absorbing black colourant

摘要

The present invention relates to a colourant for darkening the colour tone of a target polymer or of a colourant for addition to a polymer. The invention enables the production in a target polymer or polymer colourant of a substantially black colour tone so that polymers can be sorted for recycling using IR identification techniques. The present invention comprises a black colourant being a mixture comprising a carrier material, a first pigment comprising a green shade iron chrome oxide pigment and a second pigment comprising a brown shade iron chrome oxide pigment, wherein the first and second pigments are selected such that in combination with a carrier material they produce a substantially black colour tone.