Metallic ink It is a general term for inks made of metal pigments. It is a metal particle rather than a pigment particle to produce a silver or gold density ink in a high aggregation state. Metal pigments mainly include gold powder and silver powder, as well as pearlescent pigments, such as synthetic inorganic crystal materials, natural mother of pearl powder, etc. Metal powder can be used to make metal paint, color pigments, or transparent color ink mixture, so that it has a variety of metal colors. According to the thickness of the metal pigment particles, the metal ink is directly made of fine particles, and the ink is made of coarse particles.
In addition to making inks directly with metal pigments, metal inks can also be spliced with other color pigments to produce inks with special colors, which are called colored metal inks or polymetallic inks.
There are two main situations in the current production and application of metal ink. One is that the printing factory connects the metal powder with the material before use, and mixes the auxiliary materials for use at any time; The other is the finished metal ink prepared by professional ink manufacturers, which can be stored for a certain period of time to ensure that the metallic luster remains unchanged within the validity period. It can be directly used for printing at any time. Gold or silver inks have a long shelf life and will not lose luster even if stored in containers for one year. As the metal ink is made of small metals, when the ink is dry, a layer of molded metal foil is formed on the printing surface.
When the metal paint forms a thin layer on the printing surface, it will produce a higher gloss of the metal ink layer. If the metal sheet composition of the ink or the additives of the coloring ink change, the color range of the gold ink will change from red to gold. Metal ink needs special production process to form, and generally needs special printing process. The durability of these inks is usually worse than that of pigment particles, but they can be protected by printing coating or glazing layer. In addition, inks made of pink metallic pigments become thicker (thicker) on the press. However, inks made of wet paste pigments such as silver paste and gold paste are good.
The metal ink is prepared with soft object particles, so the metal sheet in the ink can form a thin metal foil, which can be flattened on the surface of a substrate as far as possible to obtain the maximum gloss. The metal ink has the characteristics of low viscosity, which is suitable for transmission in the middle of the ink roller to make the printing process cleaner. Coated paper has better absorption and curing characteristics of ink, so the ink on the coated paper has the brightest gloss. Smooth uncoated paper will also achieve better practical results, but the gloss will be slightly reduced. The paper with rough surface prevents fine metal ink particles from forming metal foil on the paper surface, thus reducing the actual printing effect of metal ink.
Some metal printing products, especially enamel products with polishing coating and clay coating, often only absorb the ink in the ink and leave metal pigment particles on the surface because they do not have enough adhesion to firmly grasp the ink. This phenomenon, called powdery, can cause the metal color to peel off from the metal surface. In order to prevent the occurrence of powdery phenomenon, the amount of water should be reduced as much as possible, because the ink with high saturation of water is easier to powdery. When printing on the surface of high coated paper or pond porcelain, an appropriate amount of desiccant should be added to the ink.
Before printing with gold or silver ink, the conventional oil-based transparent white ink printing surface is generally coated with glue. If powdering occurs, printing another layer of ink on the first layer of surface will often make up for this error. Adding mixed inks can also overcome powdery materials, but this usually reduces the gloss of the metal. In order to achieve the best results, it is recommended to use the metal version instead of the electrostatic version, which can avoid containing excessive glycerin or glycol, because these nonvolatile liquid media will slow the drying.
In addition, the purpose of printing with metal ink is to highlight its metal characteristics. It is generally required to put the metal ink at the end of printing, because the opacity of other inks will affect its metal effect.
The opacity of the metal ink will cause the operator to make excessive compensation for the ink and make the ink appear unbalanced. This should be avoided as far as possible, because it will bring too much burden to the lubrication system and cause plate pasting. Even experienced printers should use too much ink to achieve the most perfect metal effect.
The best way to prevent these failures is to add ink to a light colored image to cover the image. Then increase the amount of ink and adjust the water supply so that it is slightly higher than the minimum value to avoid ink in non graphic parts. The thin layer of metal will stand out during the drying process, providing a brighter luster. Metal ink is mainly used for anti-counterfeit printing in packaging printing and other fields, as well as printing of other printing materials (such as ceramics, enamel, cellophane, etc.).
