Introduction of UV glazing technology basic knowledge (1)

First, the application of UV coating technology

After the UV coating treatment of paper packaging products, the appearance effect can be improved, the printing quality is thick and full, the luster is full and nourishing, the decorating effect of the paper products is improved, and the folding resistance and chemical resistance are significantly improved, and the use performance thereof is improved. , To reduce the loss of products during transportation and storage. For products with high moisture-proof requirements (such as electrical appliances, etc.), their paper-based packaging products are treated with UV coating to increase the moisture resistance of the package.

UV glazing has developed rapidly in recent years, and its proportion in the packaging and printing industry is gradually increasing, but at the same time there are still many problems to be solved. The first is security issues. At present, reactive diluents used in UV varnish have certain volatility or irritation and are still polluted to the environment. The water-based UV varnish currently being developed is an ideal environment-friendly product because it replaces the active diluent with a thickener, which solves the problems of volatility and irritation.

Followed by the odor problem. Now it is gradually developing towards low odor. At present, UV-glazed packaging products have not been fully recognized by the international food and drug companies and cannot be directly contacted with food. Therefore, it is necessary to improve the working conditions and environment, improve the drying effect, and obtain a complete cure, thereby reducing the odor.

Again, there is a problem of adhesion on oxidative polymerization inks. There is not only the problem of odor, low gloss, but also difficulty in adhesive attachment. Double glossing is often used to improve the quality of UV coatings, but it also increases costs. Therefore, the adaptability of UV light oil and ink needs to be improved.

The last is to reduce the cost, although the current cost has dropped a lot, compared with the cost of BOPP composite film composite cheaper. However, in China, there are many types of UV coatings and their properties are different. So the price difference is greater. In general, the cost is still too high, and it is necessary to further reduce the cost of lacquer, coating costs, and equipment operating costs.

Second, the advantages of UV coating

1. No environmental pollution, no solvent evaporation, safe and environmentally friendly.

2. Drying speed, high production efficiency. Because the photo-curing reaction can be completed in an instant, the UV varnish can be directly stacked or entered into the next process after the printing is cured, which accelerates the production process and improves the production efficiency.

3. Not limited by the type of substrate, not only on the surface of paper, aluminum, plastic materials, etc., but also can be used for surface coating of polymer panels, furniture, metal materials, wireless materials.

4. Save space and energy, due to the UV varnish curing process, do not need auxiliary drying equipment, such as drying drying tunnel of ordinary varnish, and the UV curing machine is small in size, and the effective utilization rate is high, thereby greatly saving space and energy. , reduce early stage equipment investment.

5.Good quality, UV print surface smooth after printing, no warping, wrinkling, blistering and other phenomena, and high surface hardness, abrasion resistance, scratches, chemical corrosion resistance, and the past Compared with lamination, the cost is only about 1/4-1/3 of the lamination.

Three, double coating system introduced

Previously, for those printers who wish to continue to use standard inks and are unwilling to use UV gloss for certain printing jobs, double-glazing is undoubtedly their most suitable choice. Two coating units are usually located at the end of the press. To eliminate or reduce the possibility of loss of light (glazing oils or substrates), an aqueous coating must be applied between the wet offset ink and the final coating to isolate the offset ink and use infrared light Or heat radiation drying, can be used as the basis for UV coating adhesion. At the same time, every coating machine must have an integrated drying device, which increases the printing machine's external dimensions and equipment costs. However, the range of gloss that such devices can achieve is greater than that of a pure UV printer. In addition to the use of waterborne varnish plus UV varnish, these devices can also be used to apply the same waterborne varnish twice (eg, to increase the final gloss, apply two coats of varnish to the substrate), Or apply two different coatings (eg, applying the standard coating to the first coating unit and applying special effects to the coating through the second coating unit). There is another model of the double coater: a flexographic printing unit and a drying device are installed before the first offset printing unit to apply opaque white or a special effect primer.