What are the inks used in the screen printing of cosmetic glass bottles?
Due to the difference in printing materials and printing processes, screen glass printing has different requirements for the inks used. First of all, the most important thing for glass printing is to strengthen the bonding force between the ink and the glass surface, so that the ink does not fall off or dissolve during the use of glass products. Secondly, screen glass printing is dried at high temperature, so the ink used is high temperature resistant ink. The main inks used for glass screen printing are as follows
1. Glass glaze
According to the firing temperature, colored glaze can be divided into high temperature, medium temperature and low temperature. Low temperature (550℃) colored glaze is mainly used for the decoration of thin glass bottles. Medium temperature (580℃) colored glaze is widely used in cosmetic bottles, glass cups, etc. The high-temperature (600°C) printing color glaze of glass products is mainly used for the printing of beverage bottles. Because colored glaze contains heavy metal lead, we must pay attention to choosing high-quality colored glaze, especially for food packaging.
2. UV glass ink
The emergence of UV glass ink has largely solved the drying problem of glass screen printing, but it should be noted that excessive curing will cause the ink film to become brittle and reduce the adhesion of the ink layer.
3. Two-liquid reactive glass ink
This kind of ink is mainly used for the printing of some small glass containers such as cosmetic bottles. It is prepared on-site during use, and the storage time should not be too long to prevent the ink from hardening the conjunctiva and causing waste.
4. Thermosetting special glass ink
This kind of ink is a volatile drying ink, and it can be dried after being placed at room temperature for 10-15 minutes. In addition, in order to improve the strength of the ink film and its adhesion, it is necessary to bake at a temperature of 180°C for 10 minutes.
5. Glass pigment ink
Glass pigments contain low-melting glass powder, and binders (synthetic resins and organic solvents) are used to adjust the printability of the ink, but this ink has no intermediate colors. After this kind of ink is printed, it must be sintered in a heating furnace to make the binder in the ink evaporate and burn, and the glass powder will be softened and fixed on the glass surface.
The binder of the ink is mainly synthetic resin and organic solvent. The basic requirement for the binder is that it can complete the evaporation, sublimation and combustion process at low temperature, and avoid the residue of the binder when the glass powder is melted. Otherwise, the printing surface will be damaged. Will foam and lose smoothness.
6. Gold liquid, silver liquid and gold paste
A glass ink composed of various metal organic compounds as the main components added to the binder of the ink. The metal organic compounds used mainly include metal-sulfurized turpentine, metal-thiol and so on. Silver liquid also contains the same organic compounds. In the gold paste, because the content of gold and silver is very small, it is feasible to use it as a printing ink.