Mixed ink production background

1. Adhesion of UV Varnish to Common Ink Since the 1960s, UV Varnish has become the preferred material for glazing products because of its high gloss, instant fixation, and good resistance. However, in the early applications, the UV coating on the ordinary printing ink layer is not easy, because the chemical properties of the UV varnish and common ink are very different. The incompatibility between the two causes the UV varnish layer and the common The adhesion between ink layers is poor.
2. Glossy fade phenomenon After UV polishing, the high gloss retention time of the finished product is not long. This phenomenon is called “glossiness fades out.” As a result, the glossiness of the print product is reduced by 30%, resulting in the appearance of the printed product surface. The phenomenon of uneven gloss. The degree of dry discoloration is related to factors such as ink hiding power, ink formulation, substrate and printing conditions. However, the gloss fade phenomenon is more serious in the dark color printing area, while in the light color printing area and the blank area directly covered by the coating oil (no printing ink), the UV gloss oil can still maintain a high gloss after drying.
3. Process Attempts and Improvements In practical applications, the printing plant found that if the general ink layer is sufficiently dried before UV glazing, the gloss and various resistances of the printed product will be greatly improved. In general, dusting is required to prevent back-scratching during ink drying. When UV glazing is performed, the dusting will affect the appearance quality of the printed sheets, which will make the printing surface that should be smooth and smooth and high gloss appear frosted, which affects the glazing effect of printed products.
For this reason, the printing factory came up with a way to perform off-press water-based coating of prints, and to minimize the amount of printing and dusting. Doing so can achieve the desired quality, but it requires the paper to go twice on the printing press, or it needs to be detached from the machine for glazing, which increases the equipment use time and material consumption, resulting in an increase in the printing price. This led to the new concept of double glazing, and printer manufacturers have developed a double glazing press. The basic principle is to run paper twice to polish. First, a water-based coating is applied to a common ink layer to cover the normal ink layer, followed by UV coating. The processed product has a high gloss.
However, there are still some problems that cannot be solved, namely the drying of water-based base coats. Water-based coating oils need to be completely dried, and acrylic resins need to be agglomerated into macromolecules. Therefore, the drying speed of this process is limited. If the speed is increased, it will have a negative effect. Although double-swather printing presses have been used in some printing plants, the profitability of these machines is relatively lower than that of off-machine coating, especially for large-volume printing jobs. Double-glazing technology is ineffective. Now.

Mixed ink features

While improving the printing press and installing the double coater, the varnish and ink manufacturer is also trying to develop a new technology: to achieve on-line UV coating on the common ink layer, and later the UV ink and the common The ink was mixed and the new ink was formulated. This attempt was successful. However, there are still some problems: poor ink adaptability, unstable performance during storage, uneven gloss after coating, special coating rollers, etc. In this regard, ink manufacturers have developed a new ink - mixed ink, and has matured.
1. The glazing effect is good Take Sun Chemical's Hy-Bryte blended ink as an example, it combines the components of ordinary ink and UV curing components. The curing lamps installed at the end of the printing press and before the UV coating unit can cure the mixed ink. As long as the curing mode is correct, the printing product can maintain a uniform high gloss after polishing. The gloss effect of printed products is related to the factors such as UV varnish, printing materials, and coating units. The mixed ink is used for printing and then UV glazing. The gloss can reach 90%.
After the mixed ink is printed, it can also be painted with an aqueous coating. After the mixed ink is dried, the adhesion to the aqueous coating oil is good; the gloss is not as good as the UV coating, but it is better than the coating effect of the aqueous coating oil on the ordinary ink; the flatness is also good.
2. No special equipment The use of mixed inks is not much different from ordinary inks. First of all, the glue stick and blanket used by it are exactly the same as ordinary ink, so the printing factory is very flexible to use. When mixing with UV, you can choose mixed ink printing, and you can print with ordinary ink when you do not need to polish. Of course, this does not mean that every roller and blanket is an ideal choice for mixed inks. Also, mixed ink printing does not require special fountain solution, but it can be cleaned with general cleaning agents.
3. Excellent printability The on-press printing adaptability of the mixed ink is similar to that of ordinary ink, and the performance comparison between ordinary ink, UV ink, and mixed ink is shown in Table 1 and Table 2.
(1) The ink balance of the UV ink is difficult to control, and the ink balance control is similar to the normal ink when printing with a mixed ink.
(2) The printability of UV inks, such as dot gain, overprint and print contrast, is slightly inferior to ordinary inks, and the printing performance of mixed inks is similar to or the same as ordinary inks. Compared with UV inks, hybrid inks have very good emulsification properties, low ink adhesion, better transferability, ink receptivity and workability than high-adhesion UV inks, and printability is similar to oily inks.
(3) Since the UV photosensitive components in the mixed ink will rapidly solidify under the irradiation of UV light, the drying and drying of the common ink will be significantly reduced, so the curing of the entire mixed ink layer will be accelerated, and the back coating will not appear on the on-line coating.
(4) The mixed ink itself has greater adaptability to the fountain solution, so a clearer dot can be obtained, and no oxidized skinning phenomenon occurs in the ink tank. On-board stability is very high and does not contain volatile solvents.
4. Ability to print non-absorbent materials Mixed inks are increasingly used in the packaging and printing of folding cartons, where high gloss and abrasion resistance are required. Mixed inks exhibit good printability on non-absorbent substrates such as plastic films, aluminum foils, and gold and silver cardboards, and they can be printed with superior quality. The use of mixed inks also solves the problem of slow oxidation drying when printing common inks with non-absorbent materials.
Due to the sharp and clear printing dots of the mixed ink, the adaptability of the offset printing is continuously improved and perfected. Therefore, besides being applied to a sheet-fed offset printing, it has also been applied to a narrow-width web printing press.