UV is the abbreviation of Ultraviolet Rays. Ultraviolet rays (UV) are invisible to the naked eye. They are a section of electromagnetic radiation other than visible purple light, with a wavelength in the range of 10-400nm.
What is UV ink? What are the ingredients of UV ink?
UV ink refers to ink that is instantly cured by UV light. The main ingredients of UV ink include pigments, oligomers, monomers (active diluents), photoinitiators, and various additives. Among them, resins and active diluents play the role of fixing pigments and providing film-forming properties; pigments give inks appropriate color and covering power for substrates; photoinitiators are required to absorb photons and initiate polymerization under the interference of pigments.
Application market of UV printing:
From the perspective of printing technology, UV ink has fast speed, good film-forming properties, good adhesion to various substrates, and better scratch resistance, wear resistance, and acid and alkali resistance than ordinary inks. Therefore, although its price is much higher than that of ordinary inks, it is still widely used.
Currently, there are several fields where UV inks are used for printing.
1. Printing of non-absorbent materials
Such as polyethylene (PE) film, polyvinyl chloride (PVC) film, polypropylene (PP) film, metal foil, and non-absorbent special materials. If these printing materials are printed with ordinary solvent-based inks, a certain drying time is required, and usually powder spraying, drying rack devices, or other additives are added to the ink. However, UV inks do not have such problems at all.
2. Printing of metal materials
When UV inks are used to print on the surface of metal materials, the curing process can be shortened, and the original curing device can be simplified. At the same time, the good curing and conjunctival properties of the UV ink surface can not only improve the post-printing processing characteristics but also improve the appearance quality of the product.
3. Commercial bill printing
The printing materials and inks used in commercial bill printing are relatively special, such as carbonless copy paper, thermal paper, magnetic ink, anti-counterfeiting ink, etc., and the ink is required to have a certain resistance to discoloration, heat resistance, and stability. Therefore, it is best to use UV ink or UV varnish. At the same time, due to the fast speed of the bill printing equipment and the small amount of ink used, it also has favorable conditions for printing with UV ink.
Problems faced by UV printing
1. Price of UV printing ink
Although UV ink has the advantages of instant curing and good conjunctival performance, it is relatively expensive, which greatly increases the product cost.
2. Adhesion of UV printing ink
During the curing process of UV ink, the internal components undergo cross-linking polymerization, and the volume changes instantly to produce large internal stress, which affects the adhesion of the ink to the substrate. Although this problem can be improved by surface treatment or modification of the substrate, the fundamental solution is to seek and develop UV inks with good adsorption, small shrinkage stress, and low price. Inks with better adhesion have appeared on the market, but the price is not low.
3. Suitable fountain solution for UV printing ink
UV ink is mainly used for non-absorbent substrates, and the formulation of the ink is different for different substrates. Therefore, the fountain solution is required to have a wide adaptability to ensure the required printing quality.
Although UV printing has the above problems, with the maturity of related technologies and the expansion of application fields, its rapid development is inevitable. In the near future, UV printing will definitely be more widely used and popularized.