| 摘要 |
Thin, flexible plastic films, of the type used for the packaging of foodstuffs, may be printed using a laser marking technique by printing a lay er or layers comprising a laser sensitive material and an ink so that heating o f 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 o f 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 expose d to laser radiation such that raised markings appear on the exposed portions.
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