Toppan gold and silver ink printing are common production techniques for packaging, decoration, books and magazine covers, and commodity samples. After the products were printed with gold and silver inks that were rich in metallic luster, they were magnificent and the grades of their products were greatly improved. However, if the printing process and technical process are not properly performed, the printing quality of gold and silver inks will have a problem, which will directly affect the overall image and use value of the product. Therefore, we will take some printing quality problems encountered in the process practice and take solutions. For reference by colleagues.
First, uneven ink and silver ink printing problems and their solutions
1, printing material quality defects caused by the issue of printing quality. 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 â€‹â€‹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, printing pressure does not cause print quality problems. 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 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. Problems with printing quality caused by poor 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, the paper surface gloss is not good caused by the print quality problems. 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.
Second, the reasons for the bad glossiness of gold and silver ink
1, chemical properties are not stable. When gold and silver inks are heated and absorb moisture; when they come into contact with acids, alkalis, oxygen, or carbon dioxide, chemical reactions are likely to occur, causing the color to darken and darken, and the ink will lack gloss when printed. Therefore, when gold and silver ink (or gold and silver powder) are stored and stored, care should be taken to prevent heat and moisture, and to avoid contact with the above substances. Unused gold and silver ink (or gold, silver powder) should be sealed and stored to ensure the stability of their characteristics.
2, improper deployment of gold and silver ink. If the amount of gold and silver inks is too large and the usage time exceeds 4 hours, the gold and silver inks on the machine will be prone to oxidation and darkening due to contact with air and water vapor for a long time, which will affect the gloss of the inks of the printed products. The occurrence of a bad phenomenon, printing gold, silver ink should be used with the tune. Generally, it is appropriate to print three or four hours in a row at a time.
3, paper characteristics do not apply. The coated paper, whiteboard paper and offset paper produced by the acid papermaking process will produce adverse reactions after printing gold and silver inks, which will make the gold and silver inks on the prints dark and dark and lack gloss. In addition, non-coated paper in the high-humidity environment, chemical pulp sulfides and filler bismuth lanthanum soil will also make the paper on the gold, silver ink black and lose gloss. Therefore, in order to improve the glossiness of gold and silver ink printing, paper and cardboard containing no acidity should be selected for printing.
4, printing speed is too fast. When printing gold and silver ink, if the machine speed exceeds 3,500 per hour, the friction coefficient of the ink roller on the machine is obviously increased. The heat generated by it can make gold and silver ink black and affect its glossiness. Therefore, the speed of printing gold and silver ink should be controlled as low as possible, and it can usually be controlled between 2000 and 3000 sheets per hour.
5, the machine is not often cleaned. If the machines for printing gold or silver ink continue to operate for three or four hours, the ink fountains, ink rollers and other components on the machine will be significantly heated, which will accelerate the oxidation of the gold and silver ink on the ink fountain and the ink roller to change their color. Dark and darkened. Therefore, when printing gold or silver ink, it is recommended to clean the ink fountain and ink roller every three or four hours, and replace them with new ones for printing so that the gloss of gold and silver inks can be guaranteed.
6, printing semi-finished products stacked too high. When printing gold and silver ink, if the stack of semi-finished products is too high, the heat released from the ink layer during the drying process cannot be smoothly and timely emitted, and the gold and silver inks will also be oxidized and discolored. Therefore, when printing, attention should be paid to controlling the stacking height of semi-finished products. It is best to use a paper holder to separate semi-finished products.
Third, problems such as discoloration, skeining, stencil, and other quality defects appear in printing.
1, printing gold, silver ink fade situation. Due to the improper control of the ink-adjusting process and operation technology, such as the use of gold and silver inks for ink formulation, there is no use of gold dipstick oil and dilute silver oil for diluting and blending. If non-specific thinners are used for blending, their affinity is not good, and the gold after printing is not good. Silver powder easily falls off the surface of the paper. On the other hand, when the printing pressure is slightly insufficient or non-uniform, it will also cause the ink on the printing plate to be colored and the visual effect of the ink color is poor. To overcome this drawback, if blindly increasing the amount of ink to be used to satisfy the beauty of the layout ink color, Visual requirements, this will inevitably arise because of the lack of pressure and ink floating situation, it is prone to the disadvantages of the discoloration process. Therefore, in order to adjust the printing pressure, the pad plate should be flat and uniform, and the pressure pad should be sufficient so that the embossed gold and silver ink can penetrate into the paper fiber, and the ink layer firmly adheres to the paper surface. In order to reduce or avoid the chance of discoloration, it is also necessary to apply good ink transfer technology, except that gold oil and silver ink are used to adjust gold and silver inks, but it is also appropriate to consider adding a small amount to gold and silver ink. Transparent ink and white ink to increase the adhesion of gold and silver ink.
2, printing gold, silver ink appear to pull hair and paste quality problems. When gold and silver inks are too thick and their flowability is poor, the fibrous structure on the surface of the paper is easily pulled off due to the high viscosity of the ink. At the same time, even if the ink is too thick, uniform ink transfer and ink brushing cannot be achieved, and then ink build-up occurs. The phenomenon of ink accumulation caused the paste of lines and text parts in the printing layout. Therefore, if the ink amount is too large, the contact between the rubber roller and the chain iron roller is poor, and the position of the ink roller is unsuitable for adjustment, the thickness of the ink layer on the plate may be uneven. Thus, when the ink layer is too thick, the local layout is easy. Produce ink, paste ills. This should be adjusted by adjusting the ink's fluidity so that it maintains good transfer performance, and at the same time it should accurately control the amount of ink applied to the layout. In addition, the use of low-grade copperplate paper, whiteboard paper, and offset paper, which are easy to lose powder and lose hair, should be avoided. Gold and silver inks should be used to print off good process technologies from the source of quality to prevent the occurrence of adverse conditions.
To sum up, as long as we pay attention to the good technology and operation technology, carefully analyze the various quality problems in the printing process of gold and silver ink, continuously summarize the experience of the production process, and pay attention to taking the source of quality. Corresponding preventive measures can not only improve production efficiency, but also effectively avoid the appearance of such or such quality problems and ills, and improve the printing quality of gold and silver ink.
Reprinted from: China Ink Technology Network
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