Laser lettering on pigmented systems

Claim 1

A method for the visible inscription of high molecular weight organic material which is processed to give mouldings or surface-coating and printing ink films and which contains at least one radiation-sensitive additive which effects a change in colour, where the high molecular weight organic material is a natural resin, drying oil, rubber, chlorine rubber, oil-modified alkyd resin, cellulose derivative, polyethylene, polypropylene, polyisobutylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetal, polyacrylonitrile, polyacrylate, polymethacrylate or polybutadiene or a copolymer thereof, a polyester, polyimide, polycarbonate, polyurethane, polyether, polyacetal, a condensation product of formaldehyde with a phenol, a so-called phenolic resin, a condensation product of formaldehyde with urea, thiourea or melamine, a so-called amino resin, or one of the polyaddition or polycondensation products of epichlorohydrin with diols or polyphenols which are known as epoxy resins, and where the radiated energy is directed on to the surface of the material to be labelled in accordance with the form of the inscription to be applied and a change in colour occurs at the irradiated areas, wherein the radiated energy which is used is laser light having a wavelength in the UV range between 0.25 and 0.38 µm and/or in the visible range and/or in the IR range between 0.78 and 2 µm and the additive which effects a change in colour which is used is at least one inorganic and/or organic pigment and/or a polymer-soluble dye, without the surface of the inscribed material being visibly damaged.