With the rapid development of the packaging business, there are more and more packaging products using offset presses to print gold (silver) inks, but printing gold (silver) inks are very different from ordinary printing inks. problem. How can I print gold (silver) ink on an offset press? According to the experience of our factory gold (silver) ink printing, we should pay attention to the following aspects.
First, the deployment of gold (silver) ink Gold ink is made of copper and zinc alloy powder and gold oil blending, the powder in the copper, zinc content is different, the color of gold ink is also different. The zinc content is low, the gold ink is reddish; the zinc content is high, and the gold ink color is partial green. At present, gold powder (ink) sold on the market alone has red gold powder (ink), green gold powder (ink), and green gold powder (ink ink).
The silver ink is made from the bank's aluminum powder and silver blended oil. Different silver powder particles have different metallic luster, and the coarse silver particles have stronger metallic luster.
Offsets should be selected with high fineness and low floatation gold powder, which is conducive to uniform printing and solvent blending and better printing quality. In the deployment of gold ink, the dilute consistency of gold ink should be determined according to the suitability of the substrate, climatic conditions, and seasonal changes.
The formula of gold ink commonly used in our factory is:
Suzhou 1000 mesh gold powder 0.4 liters Tianjin 8031 ​​gold oil 0.3 liters Shanghai gold oil 0.1 liters In addition, in the gold ink appropriate to add some light yellow, bright oil, red dry oil, dibutyl ester and other adjuvants, can enhance the gold ink The affinity, viscosity, and fluidity of the ink enhance the adhesion of the gold ink, thereby improving the print transfer performance of the gold ink.
Offset generally uses 400 mesh to 1000 mesh silver powder. The silver ink formulated with 1000-mesh silver powder has a relatively poor metallic luster effect. The silver ink formulated with the silver mesh has a better metallic luster and is suitable for a large-area silver-printing product. It is worth noting that silver powder is not acid-resistant, and it will react chemically when it encounters acidic substances, which will reduce its metallic luster. Therefore, in the deployment of silver ink and silver ink in the printing adjustment, neutral additives should be used.
The gold powder and silver powder in the gold (silver) ink are characterized by high electrical conductivity, high thermal conductivity, heavy weight, coarse particles, poor adhesion, and unstable chemical properties. Therefore, in the use of its characteristics must be correctly controlled, strict process operations, in order to make the product quality to obtain satisfactory results.
Second, on the machine printing gold (silver) ink ink ink layer is more thin than the letterpress printing ink. Therefore, when an offset printing machine is used to print gold (silver) solid plates and thick lines, a secondary continuous printing or secondary stepwise printing process is often used to enhance the saturation and metallic luster effect of gold ink and silver ink.
1. Print the gold (silver) ink first. Then print the gold (silver) ink with the offset printing machine. Generally, the background color (commonly known as the background color) is used. That is to say, the hiding power is strong and similar to that of the gold (silver) ink. The ink is based on the background color. Gold ink is printed with pale yellow ink, clear yellow ink or fake gold ink, and about 10% of gold ink is added in order to increase the metallic luster. Yinyin ink generally uses fake silver ink to make the background color. Fake silver ink can be diluted by bleaching agent, white ink, black ink, de-sticking agent, No. 6 varnish, and white dry oil. The printing ink of silver ink is better than gold ink, and it can basically meet the requirements of general package printing with only one printing. If you encounter a large area of ​​silver packaging products or the use of paper is poor, you need to take two prints to be able to show a good silver luster.
2. Undertone ink on gold (silver) Ink ink on gold (silver) refers to the printing of gold (silver) ink on a layer of ink with strong hiding power, so that both gold and silver ink can be saved. The purpose is to increase the gloss of the gold (silver) ink layer and enhance the printing effect of the gold (silver) ink.
The printing quality of the base color ink is the basis for determining the printing quality of the gold (silver) ink. Therefore, the layout of the printing base ink must be flat, the ink viscosity should be large, the drying property should be moderate, and the ink layer should be thick. The drying method of the background ink is preferably a combination of osmotic drying and conjunctival drying, and the formation of the underlying ink layer should not be allowed to proceed.
The gold color ink is best used black, blue, dark red, purple, dark green ink, the above-mentioned ink is easy to bring out the metal's vivid and three-dimensional sense. Undercoat ink layer should not be too thick, as thin as possible.
The silver ink of the background color is preferably silver-gray ink. If the transparent yellow ink is used as background ink, the silver ink can be printed on it to obtain a golden glossy printing effect.
No matter whether it is printed gold or silver, it should be superimposed under the condition that the base ink layer is not completely dry. Otherwise, the ink (silver) ink and gold (silver) ink will not come off when they are wiped off.
3, gold (silver) ink printed on the ink other gold (silver) powder in addition to its own metallic luster, the more important is the surface of the light reflection, that is, gold (silver) powder is a surface color material. If the ink of other colors is printed on the gold (silver) ink layer, the gold (silver) ink layer will have a metallic luster effect. Therefore, this should be taken into account in the design of the printing process, making full use of the opaque and strong hiding power of the gold (silver) ink, rationally arranging the printing sequence, and arranging the printing gold (silver) as far as possible in the last color sequence. If it is necessary to superimpose inks of other colors on the ink layer of gold (silver), the area of ​​its layout should be as small as possible. This will not affect the performance of gold (silver) ink, but it can also prevent bad overprints. The production of printing defects. (To be continued)