Almost all production processes involve the application of identification marks to the goods manufactured. In addition to the conventionally employed processes of hot embossing, printing, stamping and engraving, laser inscription of different materials has become increasingly established over the past few years. When it comes to marking plastics, a quality equivalent to printing is required. Many polymers are difficult, if not impossible, to inscribe with lasers. In further developing and optimising its “Iriodin” pearl gloss pigment series, Merck KGaA (Frankfurter Str. 250, D-64293 Darmstadt) is endeavouring to make standard plastics laser-inscribable in different colour variants.

By adding “Iriodin LS” pigments (LS = Laser Sensitive), the company claims that polymers which were previously impossible to mark can now be inscribed in a tamper-proof manner to give a high contrast. Laser beams can produce contrasting colour reactions through chemical reactions in both the additives (colour changes in the pigments) and the polymer matrix (darkening through carbonisation). The crucial factor is that the colour reaction must be sufficiently pronounced and irreversible. As journalists were told, adding pigment to existing formulations will only affect their colour and properties slightly, if indeed at all. Apart from its primary use in the electronics industry and for marking engineering components in the automotive industry, the packaging field is also displaying increasing interest in laser coding. Since the pigments do not migrate, the marking can also come into direct contact with the contents of food packaging.

READER SERVICE: Merck brochure “Iriodin LS for the laser inscription of plastics” with detailed information on laser inscription and technical datasheets: PIE-No. 43024.