Laser imprint transfer process and its application on cigarette packets

The laser imprinting transfer process has the advantages of environmental protection, low cost and good visual effect. In recent years, it has been widely used in the field of cigarette packet printing, mainly in two aspects: First, it partially replaces the process of using laser paper. The production cost is reduced, and the second is to use the process to develop new cigarette packages and increase the added value of the products.

Process development

If the print does not need hot stamping, the laser imprint transfer process can be completed once after printing. Otherwise, the process sequence between the hot stamping process and the laser imprinting process should be considered.

1. First hot stamping, post laser imprinting transfer

The hot stamping process is prone to produce galvanized aluminum burrs and chips. If the flexographic glazing process is adopted, the electrochemical aluminum burrs, chips and the like are easily adhered to the resin glazing plate and the laser transfer film. When the laser transfer film is repeatedly used, the galvanized burrs and chips adhering to the surface thereof will be Attached to the printed product, which affects the laser imprint transfer effect, causing flaws or quality defects; if a sheet-fed gravure press is used as the coating unit, the coarser electrochemical aluminum scrap may also cause "stretching", resulting in holography The pattern is incomplete.

Bumping hot stamping can make the image appear concave and convex, but if the hot stamping plate making parameters are unreasonable, it will lead to improper bump height, which will easily cause two problems when laser imprinting is transferred: First, it is easy to be dense in text strokes. Stacking UV varnish, and second, it is easy to damage the integrity of the laser transfer film holographic pattern cell, affecting the number of times the laser transfer film is used.

In general, if you want to first hot stamping, then laser embossing transfer, you need to adjust the appropriate hot stamping plate making parameters, such as hot stamping height, concave and convex arc, etc.; select the appropriate thermal adhesive for the electrochemical aluminum, so that It maintains proper shearing force and adhesion to the anodized aluminum during the hot stamping process, thereby solving the influence of burrs and debris on the quality of laser imprint transfer.

2. First laser imprint transfer, post hot stamping

In the case of laser embossing transfer, if ordinary varnish is used, a bright film layer is formed after the holographic pattern is transferred to the surface of the printed product. Because of its low surface tension, it is difficult to achieve hot stamping on the surface, which is easy to cause hot stamping. Printed text is incomplete, leaving quality problems. Although it is possible to improve the smoothness of the surface of the film and reduce the resistance by adding certain additives (such as silicone slip agents) to the UV varnish, it also causes poor adaptability of the UV varnish. Therefore, if this process sequence is selected, it must be carefully tested to obtain accurate process parameters before mass production. In fact, from the perspective of formula, the hot-printable UV varnish is not a pure UV system material, but mainly a monomer. When UV curing, only some materials undergo cross-linking reaction, and the rest are mostly plastic materials. After curing, a certain amount of microporous structure can be formed on the surface of the printed product, thereby ensuring that the electrochemical aluminum can adhere well, but at the same time, the adjustable range of the formulation is limited.

As an emerging environmentally-friendly post-press processing technology, the laser imprint transfer process can achieve anti-counterfeiting and environmental protection effects to a certain extent, improve the grade of cigarette packs, and reduce production costs. If the characteristics of the process can be fully considered in the design of the cigarette package, it is believed that the laser imprint transfer process will be more and more widely used in the cigarette package printing industry.

　　 The above content is selected from the 4th issue of 2011, Printing and Printing , Packaging and Decoration, and more journal content, please pay attention to the journal channel.