Scraping Paper's Ink Absorption and Product Quality

The ink absorption of paper is a manifestation of the physical properties of the paper. It refers to the ability of the paper to absorb ink. Conversely, it is the ability of ink to penetrate paper. The penetration of ink into paper needs to be achieved under specific process conditions. Therefore, the basic conditions for contact and printing pressure between them are the minimum, and this condition is the basis for ink penetration and ink absorption on the paper surface. Obviously, the gloss of the paper is good, and the ink absorption is poor, the drying speed of the print is slow, and the unfavorable conditions such as the bottoming of the imprint are likely to occur. The paper with strong ink absorbency must have looser fiber structure on its surface, poor gloss, and it is easy to print flowers.

Knowing and mastering the relationship between the paper's ink absorption and the quality of the product's printing is of great practical significance for the correct handling of process technology and avoidance of blindness in the process. We know that when the ink is transferred from the surface of the printing plate or blanket to the surface of the paper, part of the ink, especially the binder in the ink, will penetrate into the fibrous tissue of the paper. At the same time, the solvent of the binder v began to evaporate. In addition, the main part of the linking material produces a chemical reaction and a physical reaction, so that the ink film on the surface of the print gradually increases the viscous hardness, and a solid film layer is formed. This is the general drying process after ink transfer. This drying principle shows that the paper's ink absorption capacity and absorption speed are essentially the ink's ability to penetrate the paper. The speed of penetration will inevitably reflect the degree of ink drying, but also affects the physical properties of the structure of the ink and the conjunctiva after being absorbed by the paper. It can be seen that the ink absorption of the paper directly affects the quality of the product.

The size of the gap between the fiber and the fiber of the paper and the gap between the fiber and the filler is a condition. In addition, the ink is composed of pigment particles and a binder. Then, under the above conditions, if the mean value of the pigment particles in the ink is much larger than the increase in the size of the gap between the fine fibers of the paper, the ink is transferred to the paper, and the ink is absorbed by the capillary action between the fibers, some of which are fine fibers. The gap absorbs only the binder and forms a filter. If the ink absorption of the paper is too strong, the link material is excessively drawn into the interior of the paper, so that the oil content in the ink layer is reduced excessively, so that the pigment particles are bound to be suspended on the surface of the paper. After the ink layer conjunctiva is dried, the print product lacks a glossy feeling. Even if some of the blots are slightly rubbed, the pigment will fall off. This is the phenomenon of imprinting powder. If the fibrous tissue of the paper is too loose and the oil absorption is too strong, the viscosity of the printing ink is low, and the printing pressure is too high. This makes it easy for the ink layer to penetrate the back of the paper. From the back of the print, it can clearly see through to the front. Print through phenomenon. If the ink absorption is too strong and the mean value of the capillary aperture of the paper is large, part of the pigment particles will be infiltrated into the paper together with the linking material, affecting the thickness of the conjunctiva of the ink layer, so that the imprinting cannot exhibit the desired color on paper. Degree will also affect the quality of printed products.

The ink absorption ability of the paper has a great influence on the drying speed of the printing ink layer. For example, when the paper with too low ink absorption is used for printing, the ink layer is fixed and dried slowly, and the back surface is likely to be dirty. Therefore, the printed paper, newspaper products, the ink used in the ink is generally the main type of osmotic drying, due to the machine printing speed, require paper should have strong ink absorption performance. The good ink absorption performance of the paper helps to enhance the adhesion of the ink film to the paper, and enhances the adhesion of the ink film to the paper. The principle of printing ink adhered to paper or other substrates is more complex, and its adhesion can be roughly divided into two types. One is the molecular force between the substrate and the ink film (also known as secondary binding force or van der Waals); The other is that after the ink is absorbed into the paper and solidified, it is equivalent to the mechanical anchoring effect. Therefore, paper or other substrates have a certain degree of ink absorption, which is conducive to improving the fastness of the printing ink film and its adhesion, and avoiding the occurrence of color printing quality defects.

To sum up, to accurately understand and understand the ink absorption of paper, to master the relationship between the paper's ink absorption and printing quality, and to scientifically and reasonably formulate appropriate and appropriate printing process measures, in order to effectively avoid and reduce operational process defects, Improve the printing efficiency and product quality has a positive guiding significance.

Reprinted from: Ink Information