Gold and silver ink printing

We know that gold and silver inks are developed from copper, zinc, and aluminum metal powders. Metal powders are the main component of inks. Because of their granular nature, gold and silver inks are more adhesive, more viscous, and more fluid. Ink is poor, so if you can not grasp the printing process, it is easy to produce dark color, uneven ink, imprinted crystal, paste, fade and other undesirable conditions.
1. The gold and silver inks are dull and lacking in metallic luster. The chemical properties of gold and silver powders in gold and silver inks are generally not stable enough. When acid, alkali, water vapor, sulfide gas and carbonic acid gas are encountered, chemical reactions will occur. , The lack of metallic luster in inks. Among them, the color shift of golden ink is changed from golden yellow to reddish brown, and then turns blackish. Because copper can produce red cuprous oxide during initial oxidation. After further oxidation, it turns black copper oxide. In addition, the gold powder is easily converted to basic copper carbonate under the conditions of relatively concentrated carbon dioxide gas and high humidity, and the gold ink on the printed product gradually becomes dark. After the silver ink is discolored, it is grayish and lacks a silver metallic texture.
In order to prevent the occurrence of the above-mentioned unfavorable conditions, gold powder and silver powder for gold and silver inks shall be formulated to avoid heat, moisture and contact with acid-alkali substances during use and storage. Unused gold and silver powders should be sealed to ensure Quality stability. In addition, if the amount of gold and silver ink is too large, the use of time is too long, the speed of the printing press is too fast, too many rubber rollers passed, and the contact pressure between the ink rollers is too large, the ink may easily oxidize and become dark. The pH of the paper is in a slightly acidic state, such as offset paper, whiteboard paper, and paperboard, which are generally acidic. After the printing, chemical reactions are likely to occur, causing the metallic and silver ink layers on the paper machine to lose their metallic luster and brightness.
The gold and silver inks should be used with adjustments. Normally, it is suitable to print three or four hours continuously at a time; the speed of the printer is controlled at 2500 to 3,000 sheets per hour; the ink roller has two sticks, and the gum is softer, higher and lower That is, the contact position with the iron roller should be adjusted so that the contact pressure is too heavy to aggravate the frictional heat and cause the ink to darken. The gold and silver ink printing paper is preferably made of glossy paper such as coated paper and glass cards, and has a strong sense of ink color after printing.
Second, after the printing of gold, silver ink hair color, color saturation is not good 1, the package lined with real or uneven. When the liner is soft, the printing pressure will inevitably lag behind. Therefore, it is impossible to maintain a full and proper contact between the ink and the paper at each graphic point in the imprinting process, so that the partial printing plate will be spurted. In addition, after the lining is used for a period of time, foreign matter such as sand, paper scraps, pulp agglomerates, and printing plates of different web sizes (relief type) will cause the lining to have a certain degree of unevenness, which is also a result of imprinting. The reason is that the printed gold and silver ink pad lining should use the neutral hard pad material, and the deformed uneven padding material should be replaced to improve the ink color quality.
2. The roller is too hard and not sticky, and the colloid is broken or not round. The roller is too hard and its adhesiveness is poor, and it is easy to make the ink transfer uneven. The lack of a good degree of circle of the rubber roller and the damage of the colloidal surface will inevitably lead to uneven ink transfer and the difference in thickness of the printing ink layer. Therefore, the gum of the printing gold and silver ink rollers should be soft and the colloid should be intact and have The more accurate center of the circle makes the surface of the entire rubber roller uniform, which is also an important condition for realizing the evenness and fullness of the printing ink of gold and silver ink.
3, gold, silver ink is too thin, poor mobility, viscosity.
4, the bottom bracket is not solid, the pressure of printing is not uniform.
5, the paper used for printing paper fiber gap, surface roughness, ink absorption.
Third, the gold and silver ink blot roughening and paste the reasons 1, improper transfer of ink. The fluidity of the ink determines the ink transfer effect and print quality. If the gold and silver inks are too thin or too thick, the edges of the layout or the overlying images may accumulate ink, making the prints thicker or appear stenciled. So, to what extent is the consistency and viscosity of printing gold and silver inks suitable? This is hard to say. There is no unified standard to regulate. Because of the different performance of printers and the different printing environment temperatures, there are differences in the printing ink concentration requirements. In general, the printer has many ink rollers, fast speeds, and high printing temperatures. The gold and silver inks are thickened appropriately so that the ink will be relatively thin after being exposed to heat, which is exactly in line with the printing requirements.
2, too much ink.
3, lining virtual loose.
4, printing pressure biased. When the pad is not flat, the bottom plate is not square enough to make the plate bow or pad pressure too heavy, it will also cause the printed text to become paste, thick, this should be a good pad technology, the plate should be pad Flat, solid, high and low pads are suitable.
Fourth, the underlying ink layer crystallization so that gold, silver ink does not adhere to 1, the underlying ink layer caused by excessive drying of crystallization.
2. The crystallization caused by over-printing of the undercoat ink layer.
3. The crystallization of the ink layer caused by the overprinting time interval is too long. After the crystallization of the underlying color ink layer, remedial measures should be taken to ensure product quality. First, a cloth can be used to wipe the underlying ink layer and damage the crystalline film to increase the adhesion of gold and silver ink. Second, you can add alkaline liquid or 389 type resin oil, industrial soap tablets in gold and silver ink. In addition, the printing pressure of the gold-silver ink layout is appropriately increased so that the gold-silver ink adheres firmly to the ink.
In summary, the factors influencing the printing quality of gold and silver ink are various, and the existence of a bad factor or the presence of several undesirable factors all constrain the printing quality of gold and silver ink to some extent. Therefore, it is necessary to seriously summarize and analyze the advantages and disadvantages of gold and silver ink printing technology. This will have a positive effect on better printing technology of gold and silver ink and improve product printing quality. Putian County, Fujian Province, printing plant Kang Qilai (extract)