This invention concerns a method of marking articles having a polyolefin surface by exposure to a laser beam. The polyolefin contains a sufficient amount of a laser radiation absorbing substance for decomposing the polyolefin, so that a black mark of decomposed polyolefin will be formed....http://www.google.de/patents/US4578329?utm_source=gb-gplus-sharePatent US4578329 - Method of marking an article having at least a polyolefin surface and an article having a polyolefin surface provided with a black mark of decomposed polyolefin
