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• Time of issue:2021-06-23 11:17
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(Summary description)The thickness of the printing ink layer of kraft paper bag refers to the average thickness of the ink layer attached to the surface of the paper in the direction perpendicular to the paper. Whether the thickness of the embossing ink layer is correct is the key factor to achieve the best printing color reduction. The ink layer on the printing paper is too thin, the ink color cannot cover the paper surface evenly, the printed part is not shiny, the color tends to become lighter, and the layer is blurred; the ink layer is too thick, when the field density on the printing paper reaches the maximum field density of the ink At the density, the quality cannot be improved, but the dots are severely increased, resulting in printing errors, such as pasting or horizontal merging, as well as blurring of dots in the dark areas of the print, and the layer is matte. Due to the complexity and variability of ink, printing conditions and substrate conditions, the thickness of the ink layer is uncertain and uneven. Kraft paper bag printing usually adopts the following principles: The viscosity of the ink is from large to small, and the arrangement is that the color ink is printed first, and the viscosity is small, and the color ink is printed first. When the ink viscosity cannot meet the layout requirements, the ink viscosity can be adjusted in advance. The transparency of the ink is from large to small. Generally, the transparency of the first printing is the worst, and the transparency after printing is good. For example, four-color printing usually uses ink, cyan, magenta, and yellow in the order. Program of ink brightness from dark to light. Generally speaking, first print silently, and then print brightly. The thickness of the ink layer is arranged from small to large. For example, when using black, cyan, magenta, and yellow order in offset printing, the ink layer thickness of black ink is 0.8 μm, cyan ink is 0.9 μm, magenta ink is 1.0 μm, and yellow ink is 1.1 μm. The point coverage ranges from small to large. Generally, the dot coverage area of small dot printing, and the dot coverage area after printing. Printing and color matching on the flat screen, the flat screen is printed first, and then printed on the spot, so that the ink layers are stacked together. When printing gold ink and silver ink on a printed product, they are usually printed on the back side. How to control the thickness of the offset layer? The thickness of the ink on the substrate has a great influence on the quality of the product. How to correctly grasp the thickness of the ink depends on many objective conditions, that is, the thickness of the ink depends on the nature of the ink. The layout and distribution of graphics and text, climate, machine speed, paper surface smoothness, etc. should be considered, and then adjusted according to different situations. 1. The influence of ink thickness on product quality Generally, the thicker the ink, the greater its viscosity, and the worse the fluidity of the ink. If the ink is too thick, the ink in the ink tank is not easy to ink, and the ink on the ink roller is not easy to be uniform, resulting in uneven ink on the printing plate. This is because it is easy to accumulate on the printing plate and also cause paper rubbing. Injury and other phenomena. If the ink is too thin, the viscosity is too small, and the flow rate is too large, the print will become light, dull, deformed, deformed, and gelatinized, and it will easily cause smearing. 2. Refer to a variety of objective conditions to flexibly grasp the ink thickness From the nature of the ink, magenta ink and black ink should be thicker, followed by green ink, yellow ink, light red and light blue should be thinner. From the perspective of the layout of graphics and text distribution, in large-area field printing, the ink should be thinner, so that the field plate can be printed smoothly and not easy to roughen; but in screen printing, the ink should be thicker to prevent dots Deformation, expansion and paste. From a climate perspective, when the temperature is high, the fluidity of the ink increases. Therefore, in order to properly control the fluidity of the ink, it should be thickened. When the temperature is low, the fluidity of the ink decreases, so it should be diluted. When the climate is dry, the ink should also be diluted. From the point of view of machine running speed, when the machine is running fast, the ink roller will generate heat when running fast, and the fluidity of the ink will increase, so the ink should be thickened. On the contrary, when the machine is running slowly, the heat generated by the ink roller is lower, so the ink should be diluted appropriately. From the perspective of the smoothness of paper properties, when the paper surface is rough, soft and absorbent, the ink should be diluted. On the contrary, when the surface of the paper is smooth, dense and absorbent, the ink should be thickened because the