The ink is composed of a colorant, a binder, an adjustability adjuster, a desiccant adjuster, and a print effect modifier.
The role of pigments:
1, to the ink with color, and according to the amount of use to determine the color of the ink, and according to the amount of use to determine the ink concentration.
2, to the ink with a certain thickness and Other physical properties.
3, to maximize the ink has a strong durability.
4, to a certain extent, affect the drying of the ink, the most obvious oxidative conjunctiva drying.
The role of the binder:
1, to the ink with a certain viscosity, viscosity, flow properties, thixotropic properties.
2, determine the ink drying type and drying speed.
3, determine the ink gloss, abrasion resistance, firmness and so on.
In the offset printing process, the ink ink layer thickness and the quality of the printed product are inextricably linked. The relationship between the size of the ink, the thickness of the ink layer, the smoothness of the paper, the strength of the surface, the absorptivity of the paper to the ink, the size of the printing dot lines, the number of graphic parts, the speed of the offset printing press, and the like. Under different printing conditions, the thickness of the ink layer and the amount of ink are not the same. To treat it differently, it is beneficial to increase the thickness of the ink layer and the amount of ink when printing.
The delivery of ink in the printing process is related to the viscosity of the ink. Because ink is a fluid substance, it has fluid properties. The viscosity of offset inks and letterpress inks is not only plastic viscosity but also structural viscosity. Ink transmission conditions in printing 1 and the viscosity of the link material; 2 temperature-related; 3 and the size of the pigment, filler; 4 and pigment and filler in the distribution of the link material has; 5 and the ink yield value.
Paper absorption of ink and what factors: 1 with the press pressure and imprint the length of time; 2 and the viscosity of the ink; 3 and the structure of the paper itself; 4 paper containing more lignin absorb ink. Such as: newsprint, with filler, plastic material less paper, that is to say the paper surface strength difference ink absorption is large.
Several factors that determine the amount of ink used When printing offsets, the amount of ink used in each batch of printed products is different. Therefore, the amount of ink used should be determined based on the classification of printed products or the nature of the materials. The general rule is:
1, full version of the field of printing products to increase the use of ink, so that the ink layer a little thicker. The ink can be diluted to make the print plain and full.
2. The screen version of offset four-color electricity points, the higher the number of outlets, the greater the amount of lines to avoid, the less the expansion of outlets, the number of electric four-color screens is 150-175 lines/inch, and the number of camera screens At 60-90 lines/inch, the more network cables, the less ink is used.
3, paper is relatively rough, poor integrity, poor surface strength of paper, ink absorption performance is relatively large. However, the surface of the paper is smooth and smooth, and the ink absorption performance is poor, and the amount of ink used can be appropriately reduced.
4. The ink speed of the offset printing machine should be slightly thicker than the speed of the vehicle when it is fast. Under normal circumstances, adjust the ink should have a certain degree of fluidity (ink printing performance is better), the viscosity of the ink should be appropriate, and there must be a certain body bone, such ink, can guarantee the normal printing product quality.
Improper adjustment of the amount of ink produced during the ills 1, the ink too much ills 1 In the role of printing pressure, the ink layer is easy to spread, but the level is not clear enough.
2 9-98% of dark spots in the graphic part of the printed product are easily caused by stencils, and dot gain is more serious.
3 printing process paper surface ink is too thick, it is easy to cause the ink layer thickness, causing the back of the printed material sticky fault.
If the ink layer is too thick, the drying speed of the ink will be slowed down, and it will also affect the matting of the print.
2. Insufficiency of ink volume 1 Because the ink layer is too thin during printing and the ink volume is too small, it is easy to cause unclear outlines of graphic elements in printed products, and the colors are not bright enough and the gloss is poor.
2 Ink is too small The printed product print is not "thick".
3 Because the ink volume is too small, the layout ink is insufficient, and the offset printing is a printing method using water dampening. The acidic solution in the offset printing fountain solution will erode the basics of the graphic and the failure of the printing plate will occur. (Wang Xincheng) (From "China Packaging News")