UV printing is a drying by ultraviolet light, a curable ink printing process, required to contain a photosensitizer compatible ink and UV curing lamps, UV ink has covered offset, screen, inkjet, printing and other fields.
UV-curable inks
UV curable ink occurred under UV (UltraViolet) light irradiation crosslinking reaction, can instantly from liquid to solid ink, so called "UV" ink. Its main ingredients include photopolymerizable prepolymers, a photosensitive monomer, organic pigments, light polymerization initiator, and other additives. Wherein the light polymerization initiator is a UV ink is the most important part is to start light polymerization. Commonly used photo-polymerization initiator with aromatic ketones. UV curable ink after UV curing / drying principle UV ink curing mainly due to ultraviolet light, under UV irradiation, UV inks in the photo-polymerization initiator absorb a certain wavelength of photons into the free state molecules become free radicals, then through intermolecular energy transfer, the polymerizable prepolymer and a photosensitive monomer into an excited state, resulting in a charge transfer complex body, the body constantly between complex cross-linked polymer cured film.
UV ink curing process is a process of photochemical reaction, i.e., under the action of ultraviolet energy, the prepolymer in a very short time curing film, in addition to causing the surface of the ultraviolet curable ink, the better the penetration depth of the ultraviolet curable liquid-state ink, and stimulate further cure the deep ink film. Traditional ink to oil as the main basis of the ink is solidified in oxidation, and a solvent or water-based inks mainly by evaporation of water or solvent cured, part of the ink can penetrate paper. Therefore, as compared with conventional inks, polymerizable ultraviolet curable inks to a more thorough drying, solvent evaporation or no contaminants, ink film 100% cure.
The main features of UV-curable oil
1. Excellent drying properties. Since the UV ink only in the ultraviolet light irradiation will be dry, even if the ink in the fountain and long-term storage, and its performance can remain stable and will not appear on the ink roller crust phenomenon. And one by ultraviolet irradiation, the ink can achieve instant drying and thorough, it's curing time is very short, usually only 1 / 10S to thoroughly dry fixation surface of the substrate, for conventional heatset and sheetfed inks Offset Inks, drying time can take several minutes or even a few days to dry thoroughly, so with UV curable ink printing jobs, short delivery times, to work with flexo, gravure comparable, and greatly improve the efficiency of print production .
2. conducive to post-processing step. UV ink printing with UV coating even after machining, print gloss obtained, and the surface smooth uniform. Even after machine polishing, you can make cutting, creasing, gluing and other packaging bronzing process can be completed immediately, so very conducive to the development of high-speed printing needs.
3. Good durability. UV UV curable ink addition to providing vivid, bright colors, but also has a strong anti-friction properties. UV ink chemical cross-linking reaction by forming a three-dimensional polymer network polymer, the use of UV inks enable printing ink solid, quick-drying and crosslinking, this ink has high abrasion performance and chemical resistance. Many used direct mail by uv ink printing on coated paper printed materials can withstand multiple folded, and can withstand intense radiation laser printing again, and therefore need to wear UV inks can be used for packaging printing.
4. Good environmental performance. Another important feature of UV curable ink is its environmental performance, because UV ink curing after the solid content close to 100%, almost no VOC (volatile organic compounds), namely the curing process emit little or no volatile organic compounds will not cause harmful strong environmental pollution, and waste less, and save energy, do not have to worry about handling hazardous flammable material, it is part of an environmentally friendly inks.
5. Printing adaptability, to meet needs of a variety of substrates in. Of course, the UV curable ink also has some drawbacks: some require NBR rubber roller or EPDM rubber roller, and sometimes may also need special blanket, blanket may need special cleaning agent, in order to prevent excessive shrinkage blanket, expansion or reduce quality . Second, it's cheaper than traditional ink is higher. However, the high cost and ultimately print performance is well worth.
UV printing and coating can be a variety of value-added printing techniques on a variety of materials including metal foils and plastic, including. The growing demand for the continuous development of UV UV market has been going on for many years, the annual growth rate higher than the world average growth rate of printing products industry nearly tripled, an increase in sheetfed flexo applications and many more It is strong.