Metal ink characteristics introduced

With the advancement of technology, inks are continuously being introduced as important materials for printing, not only satisfying the traditional printing needs, but also opening up new printing fields such as special printing, anti-counterfeit printing, etc. The printing quality is not only improved, but also conforms to environmental protection, Anti-counterfeit and other special needs.

Metal ink

Metal ink is a general term for inks made with metallic pigments. It is the use of metal particles instead of pigment particles, resulting in a high concentration of silver or gold density ink. Metal pigments mainly include gold powder and silver powder, and pearlescent pigments, such as synthetic inorganic crystal materials, natural pearl powder, and the like. Metallic paints can be used to make metallic paints. They can also be pigmented with colored pigments or blended with clear colored inks to give them a variety of metallic colours. The metal ink is divided into two types according to the coarse classification of the metal pigment particles, the ink is manufactured directly from the finer particles and the ink is produced using a coarser particle using a rubbing gold process. In addition to metal inks that can be used to make inks directly from metal pigments, they can also be combined with other color pigments to produce inks with special colors, such as tinted metal inks, or "multi-metal" inks.

There are mainly two situations in the current production and application of metal inks. One is that the printing manufacturer reconcile the metal powder with the linking material and auxiliary material before use, and adjusts the use with the adjustment; the other one is made by a professional ink manufacturer. The finished ink can be stored for a certain period of time, and the metallic luster will remain unchanged during the period of validity. Can be used directly for printing at any time. Gold or silver inks have a long shelf life and do not lose their luster even if they are stored in a container for a year. Since metal inks are formulated from fine metal foils, they form a layer of stamped metal foil on the surface of the print when the ink is dry.

When the metallic pigment forms a thin layer on the surface of the print, it will produce a higher gloss of the metallic ink layer. If the composition of the metallic ink of the ink or the additive of the color ink is changed, the color range of the golden ink will change from reddish gold to golden yellow. Metallic inks require special manufacturing processes to form, and generally require specialized printing processes. These inks are generally less durable than pigment particles but can be protected with a print coating or glaze layer. In addition, inks made from powdered metal pigments are generally thickened (thick) on the press. However, inks made from wet paste pigments (eg, silver paste, gold paste) are better.

Metallic inks are formulated using softer particles. Therefore, thin metal foils can be formed in the ink sheet to spread as much as possible on the surface of the sheet-printing material. Metal inks have low viscosity characteristics and are suitable for transfer between ink rollers, making the printing process cleaner. The coated paper absorbs the fixed ink better, so the ink on which the ink is printed is the brightest. Smooth non-coated paper also gives better results, but the gloss is slightly reduced. The rough surface of the paper prevents fine metal ink particles from forming metal foil on the surface of the paper, thereby reducing the printing effect of the metallic ink.

Some substrates, especially polished and clay-coated enamel products, do not hold the ink firmly on the surface of the substrate due to insufficient adhesion and tend to absorb only the varnish in the ink, while the particles of the metal pigment Stay on the surface. This phenomenon, known as "powdering", causes metal color to peel off from the surface of the substrate. To prevent "powdering", the amount of water should be set to a minimum, because inks with higher water saturation are more prone to "powdering." When printing on high coated paper or porcelain surfaces, an appropriate amount of desiccant should be added to the ink.

Before printing with gold or silver ink, the surface of the substrate is usually sealed with a conventional oil-based clear white ink coated with a glue. If "powdering" has already occurred, printing another layer of ink on the surface of the first layer will often make up for this fault. Overprinting the varnish can also overcome powdering, but this tends to reduce the metallic luster. For best results, it is recommended to use a metal plate instead of an electrostatic plate. This prevents the fountain solution from containing excessive amounts of glycerol or ethylene glycol because these non-volatile liquid media slow drying. In addition, the use of metal ink printing function is mainly to highlight its metal characteristics, due to the opacity of other inks will affect the metal effect, therefore, in the arrangement of printing color sequence, generally require the metal ink on the final printing.

The opacity of the metallic ink can cause the operator to compensate for excess ink, causing the ink to appear unbalanced. This situation should be avoided as much as possible, because it will impose excessive burden on the dampening system and lead to scumming. Even experienced printers use the excess ink to achieve the perfect metal effect. The best way to prevent these malfunctions is to add ink to a lighter color image so that it covers the image exactly. Then increase the amount of ink, and adjust the amount of water supply, making it slightly higher than the minimum, so as to avoid the non-graphic part of the ink. The thin layer of metal will protrude during the drying process, providing a brighter luster. Metal inks are now mainly used in security printing, such as packaging and decoration printing and other printing materials (such as ceramics, enamel, cellophane, etc.) printing.

Reproduced from: Fine Chemicals