Method for coloring gravure printing machine ink
Any color has three characteristics of hue, lightness and saturation. Therefore, the above three factors must be considered in the toning process. Although black is theoretically the complete absorption of light, black still has luster. The ink is "submerged by pigment (toner) and resin binder", and the pigment particles are surrounded by a layer of nearly transparent resin oil, which refracts and reflects light. Therefore, we can feel that black ink is printed on the substrate and still has a certain luster. Pigments often account for 8% to 35% of the ink composition. The amount of the pigment determines the concentration of the ink and has a great effect on the ink. Such as: relative density of ink, transparency, heat resistance, light resistance and resistance to chemicals. In the ink coloring process, the ink used is determined according to the actual printing process, the thickness of the ink layer, the printing substrate, and the like. When selecting inks, the gloss, hue, tinting strength, hiding power, etc. of the ink itself should be considered. Gloss - Gloss can be measured either by instrument or by the naked eye. Usually in the toning process, it is only observed by the naked eye. Of course, for special situations, it is necessary to measure with an instrument, such as a chromatograph. Gloss is actually the extent to which an ink print reflects light in the same direction after being exposed to light. It directly affects the appearance of printing and is a very important indicator. At the same time, when selecting the ink, it is necessary to distinguish whether the ink itself is a bright, semi-light or matte ink, and whether the same type of ink should be used. If the printing ink is a printing ink (chlorinated polypropylene resin type) or a surface printing (polyamide resin) ink, it must be formulated for the same ink to avoid mixing errors and cause unnecessary loss. Hue - the basic characteristics of color, due to the difference in quality, when grading, first consider whether the hue is consistent, and the detection method is usually observed and compared by scraping. The specific practice of observing hue is:
1 On a flat glass coloring platform, the standard sample is separated from the color tone by a distance of 1 to 2 cm.
2 Take the scraping paper and tiling the glass stand, then take the coloring ink, and scrape the sample with a glass shovel and compare the results.
Contrast results are compared to two important factors:
1 opacity - the degree to which the ink covers the background color. The better the opacity, the worse the transparency. The level of transparency affects the efficiency of ink color registration and the extent to which it is affected by the printed substrate. Such as blue is lighter yellow, and the ink hiding power is good, and it is closely related to the ink itself. Such as the thickness factor, under normal circumstances, the hiding power of white ink is related to the thickness of titanium dioxide particles, the coarse covering power of the particles is not good, the printing is easy to agglomerate; the particles are fine, the hiding power is good, the surface is uniform, smooth and delicate. White inks generally require a diameter of no more than 15 μm, and other color inks may not exceed 12 μm.