| 摘要 |
To form a durable marking in the top layer of paper substrates, at least one of the lower layers is treated with laser energy before the top layer is applied. The top layer is opaque using a printing and/or at least a varnish and/or at least a metallizing or combinations of them. A coating is directly under the top paper layer, which has no pigments or contains white or colored pigments. The coating is calendered and can also be varnished. The same process can be used with layers of thicker fiber webs, of natural fibers, to give a cardboard product. The laser energy metallizes the surface to take printing and/or a varnish. The lower layer surface is treated with a carbon dioxide laser. The metallizing process uses copper, aluminum, gold or silver. The marking is a logo, name, trade mark, an image, or a security marking. The paper substrate is in a weight of 40-400 g/m<2>.
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