Method for printing thermoplastic materials using a laser

摘要

A method for thermally printing on a dark thermoplastic material (16) with a color that is sufficiently contrasting to the color of the underlying material to make the printing clearly legible and thus be able to replace labels on products such as batteries, includes placing a layer (18) of similar thermoplastic coating material on top of the material prior to printing. A beam (26) of focused energy melts the surface of the underlying material (16) and the coating material (18) so that the coating material adheres to the underlying material to form a contrasting color layer. The excess coating material that is not adhered is then removed. Alternatively, rather than placing contrasting color coating plastic material over the material that is to be printed on, the material can first be coated with a substance which alters its characteristics when melted so that the color of the material when melted is sufficiently different from its normal color to provide the necessary contrast.