The Application of Gravure Gold and Silver Ink and Problems to Be Noted (I)

With the development of society and the improvement of living standards, people are increasingly demanding the packaging of goods. In some fine products such as cigarette packets and wine labels, gold or silver ink is often printed. Gold and silver inks can exhibit metallic luster, giving people a solemn, luxurious, splendid and colorful feeling that cannot be represented by spectral colors. Therefore, gold and silver inks have been widely used in packaging and decoration printing. The use of gold and silver inks on commodity packaging and trademark labels can not only embellish other colors, but also improve the overall product quality. The importance of improving the printing quality of silver ink is self-evident.

First, the composition of gold and silver ink

Like other inks, gold and silver inks are mainly composed of pigments and linking materials. Simply put, gold inks are made of gold powder and gold transfer oil. Silver inks are made of aluminum powder and silver oil. Blended.

1. pigment. We know that pigments are colorants in inks. They give inks a certain color. Pigments in gold and silver inks are made by grinding metal powders, mainly gold powder and silver powder.

The pigment in gold ink is gold powder, which is actually a powder made of copper and zinc alloy. The content of zinc in gold powder is generally about 8% to 30%, and the zinc content is between 8% and 12%. The color of gold ink is reddish, and it is customarily called red gold. The color of gold ink with a zinc content of between 20% and 30% is partial blue. It is generally called green gold, and is between red gold and green gold. Green gold. In gravure printing, the golden ink used in the deployment of gold ink is generally used for the 800-point gold powder, and the surface of the gold powder particles are mostly coated with a surfactant, and can be better combined with the resin binder.

Silver powder is actually aluminum powder and is composed of 65% aluminum flakes and 35% volatile hydrocarbon solvents. Aluminum pigments have a small specific gravity and are easy to float in liquids. What is used in the gravure silver ink is the floating silver powder that has floating ability in the link material. The silver ink generally uses 400 to 1000 mesh silver powder. If a silver ink is printed on a large area, a lower number of silver powders, such as 400 mesh silver powder, may be used to produce silver ink, which has a high metallic gloss after printing.

2. Link material. The binder is a liquid component in the ink. On the one hand, it is the carrier of the pigment, so that the powdered pigment particles can be uniformly dispersed therein. On the other hand, it is also used as a binder so that the pigment can be finally fixed. Substrate material surface. The binder material largely determines the viscosity, viscosity, flowability and drying performance of the ink. Therefore, the quality of the binder material directly affects the performance of the ink.

The linking material used in gold and silver inks is a special varnish, which is generally called gold transfer oil or silver regulating oil. The main components are oil, resin, and organic solvent auxiliary materials. The linking material of gravure gold and silver ink should meet the following conditions: 1 Must have enough viscosity to combine well with gold powder or silver powder. 2 The transparency must be high, and it cannot influence the hue of gold and silver ink. 3 The acidity of the transferred oil or silver oil is low, otherwise it will cause chemical reaction of the powder or silver powder. 4 gold transfer oil or silver transfer oil should also have fast-drying and quick fixability, to prevent the gold ink cartridge or silver ink print back sticky.

Second, the characteristics of gold and silver ink

1. The fineness of the ink. The better the fineness of the ink, the better the dispersibility of the pigment particles. Compared with the pigments in other inks, the pigment particles of the gold and silver inks are coarser, and it is easy to block the printing cylinders during the gravure printing process. Caverns, resulting in blockages and reduced ink transfer rates. Therefore, when deploying gold and silver inks, it is necessary to select gold powder and silver powder with high fineness and good floatability so as to facilitate uniform deployment and get a good print.

2. The gloss of the ink. The glossiness of gold and silver inks is largely related to the particle size of gold powder or silver powder. In general, the larger the particles, the better the gloss of the ink; conversely, the smaller the particles, the less the gloss of the ink. However, it is worth noting that with the increase of metal pigment particles, the printability of gold and silver inks will also decrease, the transfer performance will be relatively poor, and printing defects such as stencil printing will easily occur.

3. Heat resistance. Compared with the pigments in other inks, the gold powder and the silver powder in the gold and silver ink have the characteristics of high conductivity and high thermal conductivity, and the golden ink has poor heat resistance and is easily discolored when exposed to heat. Therefore, high temperature and heat accumulation should be avoided during use. The silver ink has good light and heat reflection properties, good heat resistance, and is not susceptible to discoloration under high temperature conditions.

4. Chemical instability. Silver ink chemical properties are relatively stable, but the silver ink is not acid-resistant, and can easily react with acidic substances, thus reducing the metallic luster of the imprint. Therefore, neutral auxiliary materials should be used for printing in the printing process. This should be paid special attention. . The chemical nature of gold ink is not stable enough. It will cause chemical changes in different degrees when it comes in contact with acids, alkalis, and sulfides. It will reduce its metallic luster and gold ink will appear black. Second, gold ink is also very easy. Discoloration occurs due to chemical reaction with air and water vapor. Therefore, be sure to seal the container tightly when storing the gold ink.

Third, the design process should pay attention to some issues

According to the type of substrate materials and printing process, reasonable layout design, not only to do a nice appearance, but also fully take into account the characteristics of gold and silver ink and printing process, as far as possible the occurrence of printing failures.

1. In general, gold and silver inks are mainly applied in the field parts or color patches, and it is better not to design them into gold or silver for very small texts of Yin, Yang and levels.

2. When printing gold and silver ink on paper, the background ink is usually laid first. For example, when printing silver ink, first lay a light layer of white ink, and then print the silver ink. This can not only improve the gloss of the silver ink layer, but also Strengthen the silver ink adhesion on paper.

3. If the substrate material is aluminum foil or vacuum aluminized paper, transparent yellow can be printed on it to achieve the golden effect; in the composite film printing process of plastic film, the transparent yellow is printed on the OPP plastic film and then the aluminum foil is compounded. It can also achieve a golden effect, which can not only save expensive metallic ink, but also achieve the desired effect.

4. In the process of plate design, the order arrangement of gold and silver inks should be taken into consideration to ensure the metallic color.

5. If it is a printed product, after printing gold ink and silver ink, UV coating or water-based coating should also be considered, or the print should be coated to prevent oxidation or discoloration of the gold ink.