Analysis of Printing Failure of Toppan Gold and Silver Ink--Uneven Problem

Toppan gold and silver ink printing are common production techniques for packaging, decoration, books and magazine covers, and commodity samples. After the products are printed with gold and silver inks that are rich in metallic luster, they look magnificent and the grades of their products are greatly improved. However, if the printing process and technical process are not proper, the printing quality of gold and silver inks will be a problem, which will directly affect the overall image and use value of the product. Therefore, the author made some analysis and discussion on some of the printing quality problems encountered in the process of practice for reference by peers.

First, uneven ink and silver ink printing problems and their solutions

1. Print quality problems caused by defects in plate properties. When gold or silver inks are printed using copper or zinc plate materials, the flatness and gloss are poor because the plate surface is susceptible to oxidation. In addition, because the surface of the metallic material has the defects of poor ink-receptivity and poor ink-transmitting property, it is easy to cause the printing ink color to be false, and the imprinting is imaginary and the bottom-out phenomenon occurs. Therefore, printing a large area of ​​the field version, should use the production of resin plate for printing, because the resin plate texture is soft, flexible, and its surface has a good gloss and ink affinity, can better improve the printing ink color quality.

2. Print quality problems caused by uncomfortable printing pressure. When the gold and silver inks are printed by letterpress printing, due to improper control of the pad printing technology, insufficiently uniform pad plates, insufficient height pad, and insufficient solid plywood bottom support, it is difficult to meet the pressure required for uniform transfer and adhesion of gold and silver inks. It is easy to cause uneven printing on the printing ink layer, making the ink on the local layout false and floating. In addition, when the gold and silver powder particles are coarse, it is more difficult to smoothly and evenly adhere to the paper surface. In order to avoid this kind of unfavorable situation, when printing gold and silver inks containing field layouts, the pad plate should be flat and firm, uniform, and the pad height should be adequate. The material of the bottom pad should use small elasticity coefficient and good hardness. material. The bottom of the printing plate is preferably made of metallic materials, such as aluminum plates, cast iron magnetic plates, and the like, and its compressive strength is not easily deformed, and the printing quality of gold and silver inks can be improved.

3. Printing quality problems caused by poor ink adjustment and improper ink supply. When the gold and silver inks are discomforted and the ink is too thin and the concentration is insufficient, the ink transfer and the coating effect are poor, and the layout is liable to cause ink unevenness. For example, if the ink layer is thick in some areas, and some ink layers are over When it is thin, the ink is not true. In this regard, by adjusting the ink's fluidity, some auxiliary materials such as phenolic resins should be properly added to improve the printability of gold and silver inks. On the other hand, proper amount of ink should be adjusted, and the ink in the ink fountain is often agitated to maintain a uniform and continuous amount of ink, so as to meet the demand for the amount of ink applied on the layout, and to prevent insufficient supply of ink and abnormality. Ink flower.

4. Print quality problems caused by defective rubber rollers. The rubber roller is an important part of the ink transfer, when the rubber roller colloid deformation eccentric loss of a good degree of circle, poor contact with the ink roller; colloidal damage or gel too hard, so that poor elasticity, poor adsorption and other adverse conditions exist, It is difficult to evenly and perfectly transfer the gold and silver ink to the layout. This will result in the ink layer of the layout being not saturated.

5. Print quality problems caused by poor paper surface gloss. When the surface roughness of the paper sheet is poor, in the imprinting process, the protruding paper surface has a large amount of ink absorption, and the recessed paper surface is less likely to be stained with ink, and the amount of ink sucked is small, so that the exposed bottom defect is likely to occur. Therefore, printing gold and silver ink should use paper with good surface gloss as much as possible, such as coated paper and glass cards. However, because what kind of paper is used is often not unilaterally determined by the printing company, when printing on paper with poor paper glossiness, the background color can be printed on the paper surface first, and then at the end. The gold and silver inks are superimposed on the color, which can avoid the disadvantages of gold and silver ink blotting.

(to be continued)