Metallic printing ink (metallic printing ink) refers to the ink prepared with metallic pigments, which has metallic luster. Generally speaking, gold ink and silver ink are such inks. The pigments of metallic inks are mainly gold powder and silver powder (copper powder and aluminum powder), and other pigments can also be added to produce inks with special colors, called colored metallic inks. When the binder is acidic, the copper powder will react with a small amount of sulfur and it will easily turn black; after printing, it will gradually lose its luster with the sulfur in the atmosphere. Therefore, the gold ink can also use aluminum powder and dyes as pigments, but The gloss is slightly poor.
The binder of metal ink generally uses resin with extremely low acid value and amine value, so as not to affect the gloss of the ink, such as ethyl cellulose, nitrocellulose, polyvinyl acetate, ketone resin, polyphthalamide resin, and add some wax To improve the suspended state of pigments. Metallic inks can also be formulated to be solvent-based, but they are often ready for use due to their low sluggishness. The polarity of the solvent does not need to be too large, otherwise the pigment will easily precipitate due to excessive wetting. Xylene, isopropanol solvents, etc. can all be used as solvents for metallic inks.