The new dye, marketed as Macrolex Red A, is offered by plastics and chemicals supplier Lanxess (Leverkusen, Germany). It is foreseen as an alternative to halogen-bearing products with a color index of Solvent Red 135 (S.R. 135). Macrolex Red A is a soluble, organic dye suitable for use in many amorphous and semi-crystalline engineering plastics including polystyrene (PS), polycarbonate (PC), ABS, PMMA and polyethylene terephthalate (PET). Coloration can range from transparent to full coverage, depending on the polymer and combination of colorants.

"Many of our customers in the foodstuffs or the automotive industry, for instance, want to position themselves in the market with halogen-free products," explains Dominik Risse, head of colorants marketing at Lanxess. He notes that a "halogen-free" label refers not only to the base polymer but also to any additives included in it. Solvent Red 135 colorants often contain halogenated perinones.

Unlike those, Macrolex Red A contains no halogens in its chemical structure, yet features a similar red shade with a yellow undertone. In addition, the supplier says it is more soluble in many polymers, which helps ease processing and can also prevent colored stippling in the product. Colored masterbatches can also have higher dye concentrations. The tinting strength of Macrolex Red A is about 3.5 times greater than that of S.R. 135 containing halogen, according to Lanxess.