In addition to the function of packaging containers in daily life, packaging bags also bear the effect of publicity and promotion. Since the development of packaging bags, many rich bag types have been derived, and products made with printed content, materials and bag types. As the demand for packaging bags increases, the quality requirements for packaging bags are getting higher and higher, including food safety, printing content, and preservation of the taste of packaging products. Wait, today we will focus on introducing the external aspects to you, analyzing the color difference problem in the printed content. Composite packaging bags, aluminum foil bags, plastic packaging bags Reasons 1. Printing color difference caused by poor pre-inking device When the circularity of the ink fountain iron roller is poor or there is wear and tear, the ink fountain steel plate also wears and deforms, and there is a mechanism to control the rotation of the ink fountain roller. Defects, so that the amount of ink in the printing process is not stable, it will also cause the generation of printing color difference. In addition, attention should be paid to the reasonable ink feeding device. The ink in the ink fountain should be increased or reduced in an all-round way. There are two adjustment methods. One is by adjusting the ink fountain steel sheet and the ink transfer (ink supply). It is realized by the gap between the iron rollers; the second is realized by adjusting the rotation radian of the ink transfer iron rollers. Reason 2. Printing chromatic aberration caused by poor ink roller. On the machine that prints color prints, there are generally three types of ink transfer rollers, ink distribution rollers and inking rollers. Among them, the ink transfer rubber roller and inking roller have the greatest influence on the intensity of ink color. . Therefore, the elasticity, viscosity, circularity, hardness and surface finish of the ink roller largely determine the ink quality of the printed product. If the elasticity of the inking roller is poor, the viscosity is insufficient, the roller body is eccentric, the colloid is too hard and the colloid finish is poor, etc., it is easy to cause uneven or unstable ink brushing during the printing process, so that the printing ink color of each printed sheet is inconsistent. Reason 3: Printing color difference caused by poor dampening If the lithographic printing process is not suitable for dampening, it is also prone to printing color difference. In addition, if the water roller melting sleeve is used for aging or adsorbing ink and impurities, it will affect the water absorption of the water roller and the uniform transfer of the fountain solution. Furthermore, if there is water leakage in the water hopper device, it will also affect the uniform transportation of water on the printing plate. The existence of these bad conditions will destroy the uniform and stable transfer of the ink on the layout, resulting in differences in the ink color of the printed products. Reason 4. Printing chromatic aberration caused by poor ink. The thickness and viscosity of the printing ink layer are not sufficiently reconciled, and it is easy to produce printing chromatic aberration. When printing, only a moderately uniform printing ink layer can better ensure the ink quality of the printed product, and effectively prevent the occurrence of printing sticking problems. Reason 5. Printing color difference caused by pressure discomfort The ideal printing process is based on the “three levels”, which can make the printed matter obtain a relatively uniform ink color under the action of a relatively thin ink layer through the balanced printing pressure. If the printing pressure is insufficient or uneven, and there is poor contact between the liner and the printing plate, it is also necessary to increase the amount of ink to meet the visual effect of inking on the plate, but this will not only increase the consumption of ink It is also easy to produce color difference in printing and quality problems of sticking and smearing of printed products. Reason 6. Printing color difference caused by poor substrate material In the food packaging bag printing process, we can find that the difference in the substrate material is also one of the reasons for the printing color difference, such as the difference in the gloss and hue of the substrate. Printing color difference problem. Taking this embossed aluminized paper as an example, there are differences in the hue of the aluminized paper surface, which will cause inconsistencies in the printing color rendering effect.
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