| 摘要 |
<p>Thin, flexible plastic films, of the type used for the packaging of foodstuffs, may be printed using a laser marking technique by printing a layer or layers comprising a laser sensitive material and an ink so that heating of the laser sensitive material by absorption of laser radiation burns the ink selectively, so causing markings to appear. A further process for marking a flexible plastic material using a laser is disclosed, whereby to a surface of a substrate comprising said flexible plastic material a laser sensitive material which is or is associated with a material that generates gas on heating is applied, this is coated with a gas impermeable layer, then exposed to laser radiation such that raised markings appear on the exposed portions.</p> |
