The printing inks used in aluminum foils are mainly divided into two categories: one is polyamide inks, and the printing inks have good adhesion, dispersibility, gloss, wear resistance, and solvent release properties for printing on various types of substances. Because of its softness, it is mostly used for the printing of plastic films. When it is used for the printing of aluminum foil as the base material, the excellent performance of the ink can be expressed, and the heat resistance also meets the requirements of aluminum foil printing.

The other type is a complex aluminum foil ink whose main component is vinyl chloride-vinyl acetate copolymer resin/acrylic resin. It is characterized by its bright color, high concentration, particularly strong adhesion to aluminum foil, and good transparency. The selection of pigments does not use toxic components such as heavy metals and is widely used in the packaging of medicines and foods.

When using the following aspects should be noted: gravure printing ink drying is completed by solvent evaporation, the role of heat and wind to promote ink drying. The drying speed of the ink should be matched with the printing speed and the drying device, and they should be adjusted based on them. When the drying is too slow, the quick-drying solvent or the quick-drying balance agent should be added to the ink, and when the drying is too fast, slow-drying is added to the ink. Solvent or slow-thaw thinner. In order to ensure that the ink does not precipitate during storage, the viscosity of the ink is generally high. When printing, the ink should be diluted to achieve the required viscosity and fluidity. This depends on the machine's structure and printing speed. The No. 4 viscosity cup measures the viscosity of the ink and the machine speed is between 20-80 m/mm. Viscosity between 22-28 seconds.

The more viscous ink, when using a large amount of release agent, should be evenly stirred, so that the release agent is evenly distributed in the ink. Since the temperature and humidity in the room have an influence on the ink concentration, it is preferable to use an ink concentration detector to determine the amount of the solvent to be added, and to measure the ink concentration at regular intervals according to changes in temperature and humidity.

Source: 21st Century Fine Chemicals Network