The hottest mixed ink realizes efficient online UV

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Mixed ink realizes efficient online UV glazing

background of mixed ink

poor adhesion between varnish and ordinary ink

since the 1960s, UV varnish has gradually become the preferred material for printing glazing because of its high gloss, instant fixation and good resistance. However, in the early application, UV glazing on the ordinary printing ink layer is not easy, because the chemical properties between UV varnish and ordinary ink are very different, and the incompatibility between them leads to poor adhesion between UV varnish layer and ordinary ink layer

2. Gloss dry fading phenomenon

after UV glazing, the high gloss of the finished product does not last long. This phenomenon is called "gloss dry fading". As a result, the gloss of the printed product decreases by 30%, resulting in uneven gloss on the surface of the printed product. The degree of dryness and fading is related to factors such as ink coverage, ink formula, substrate and printing conditions. However, the phenomenon of gloss drying and fading is more serious in the dark color printing area, while in the light color printing area and the blank area directly covered by the varnish (without printing ink), the UV varnish can still maintain a high gloss after drying

3. Process attempt and improvement

in practical application, the printing factory found that if the ordinary ink layer is fully dried before UV glazing, the gloss and various resistance of the printed product will be greatly improved. Usually, in order to prevent the back of the ink from rubbing dirty during the drying process, it is necessary to spray powder. When UV glazing is carried out, powder spraying will affect the appearance quality of the printing sheet, making the printing surface that should be smooth, flat and high gloss appear frosted, which affects the glazing effect of the finished printing product

for this reason, the printing factory came up with a method, that is, to polish the printed matter off the machine, so as to reduce the amount of printing powder to a minimum. In this way, the expected quality can be obtained, but the paper needs to be walked on the printing machine twice, or it needs to be polished off the machine, which increases the use time of equipment and material consumption, resulting in an increase in printing wages. This led to the new concept of double glazing, and a printing machine manufacturer developed a printing machine with double glazing structure when using thermoplastic grade B1 materials. Its fundamental principle is to realize twice glazing by one paper feeding. First, water-based glazing is carried out on the ordinary ink layer to cover the ordinary ink layer, and then UV glazing is carried out. The sculpture products processed by this process are no longer traditional sculpture products with high gloss

however, there are still some problems that cannot be solved, that is, the drying of water-based primer varnish. In order to dry the water-based varnish thoroughly, the acrylic resin in it needs to polymerize into macromolecules. Therefore, the drying speed of this process is limited. As long as the speed is increased, it will bring negative effects. Although the double glazing unit printing machine has been applied in some printing plants, the operating profit of these machines is relatively low compared with that of off machine glazing, especially in the face of large quantities of printing live parts, the double glazing process is powerless

characteristics of mixed ink

while improving the printing machine and installing the double glazing unit, the glazing oil and ink manufacturers are also trying to develop a new technology: realize online UV glazing on the ordinary ink layer, and then mix the components of UV ink and ordinary ink to prepare a new ink. This attempt has been successful. However, there are still some problems: poor adaptability of the ink on the machine, unstable performance during storage, uneven gloss after polishing, the need for special coating rollers, etc. In this regard, ink manufacturers have developed a new ink - hybrid ink, and has become mature

1. Good glazing effect

take the hy bryte hybrid ink of Sun Chemical Company as an example, which has both common ink components and UV curing components. The curing lamp installed at the end of the printing machine and before the UV glazing unit can cure the mixed ink. As long as the curing method is correct, the printed matter can maintain a uniform high gloss after glazing. The gloss effect obtained by printing is related to UV glazing oil, printing materials, glazing unit and other factors. Using mixed ink printing and UV glazing, the gloss can reach 90%

after printing with mixed ink, it can also be polished with water-based polish. The adhesion between the mixed ink and water-based varnish after drying is very good; Although the gloss is not as good as UV glazing, it is better than that of water-based glazing oil on ordinary ink, and the oil delivery valve has a noise light effect; The flatness is also good

2. No special equipment

the use of mixed ink is not much different from ordinary ink. First of all, the rubber stick and blanket used in it are exactly the same as those used in ordinary ink printing, so the printing factory is very flexible to use. When online UV glazing, you can choose to print with mixed ink, and when you don't need glazing, you can print with ordinary ink. Of course, this does not mean that every kind of cot and blanket is an ideal choice for mixing ink. It is used for product testing and mass testing. Similarly, mixed ink printing does not need special fountain solution, but it can be cleaned with general detergent

reprinted from: Longjiang printing

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