Significance of ink concentration control during printing

The so-called ink concentration is also the coloring power of the ink, which is a common name that reflects the degree of ink dispersion and the size of the pigment in the ink. That is, the higher the degree of pigment dispersion, the higher the ink concentration; the higher the pigment content in the ink, the greater its concentration. In addition to pigments that determine the concentration of ink, binders, fillers, additives, etc., to a certain extent, also affect the concentration of ink. The production process shows that the ink concentration is one of the important indicators affecting the printing quality. Therefore, it is very important to correctly understand and understand the conditions related to the ink, to control the production process of the printing process, and to improve the printing quality of the product. .

Ink is a hydrophobic colloid, which is a homogeneous mixture of pigments, binders, fillers and additives. Pigments are coloring substances that play a role of coloration in the ink. It is a colored substance that is insoluble in water and is not dissolved in the binder but can be uniformly dispersed in the binder. It is a powdery solid. The size of the pigment in the ink determines the durability and concentration of the ink and also affects the drying performance of the ink. As the main material for color development, pigment plays a decisive role in the quality and suitability of the ink. Therefore, for printing, only pigment particles are fine, oil absorption is large, specific gravity is small, hiding power is large, coloring power is strong, stability is good, color is small, color is bright, and has heat resistance, light resistance, alkali resistance, etc. The performance of the printed ink can achieve better quality results. According to the pigment's properties and chemical composition, pigments are classified into inorganic pigments and organic pigments. Inorganic pigments include various metal oxides, chromates, carbonates, sulphates, and sulphides, etc., such as aluminum powder, copper powder, carbon black, zinc white and titanium white, which belong to the category of inorganic pigments. Inorganic pigments have good light and heat resistance, and have a large specific gravity and strong hiding power, but do not adapt to multi-color and high-speed printing requirements. Common organic pigments include chromogenic pigments and lake pigments. Chromatic pigments mainly include phthalocyanine pigments, nitroso pigments, azo pigments, and reducing pigments. The lake pigments include basic dye lakes, azo lake dyes, acid dye lakes, and the like. The vast majority of organic pigments have good coloring power, small particles, light weight, soft texture, bright color and high concentration, and are the main raw materials for color inks. The binder is also the main component of the ink. It is a raw material that makes the ink a fluid and has a certain viscosity. It plays a role in mixing and mixing solid particles such as powdery pigments, and causes the attached pigments to transfer and adhere. On the print, at the same time make the print with a certain degree of gloss. Its color, tensile strength, viscosity, water resistance, and drying properties are important factors that affect the performance of the ink. The amount of it is also an important condition for changing the flowability and concentration of the ink. The filler is a fine, white, powdered solid material that can be uniformly and well dispersed in the binder. Potassium sulfate, magnesium carbonate, calcium carbonate, and aluminum hydroxide all belong to the fillers, and they play a role in adjusting the ink's ink, consistency, and concentration in the ink. After the pigments, binders, and fillers in the ink are processed into finished inks with a certain amount of ratio, the thick, light, and dryness of the original ink may not always be able to adapt to various conditions because of different printing conditions. , Generally through the use of some additives to adjust, such as anti-adhesives, detackifiers, dry oil, bright light and light oil, etc., these additives added to the ink will change the ink concentration.

The density of the ink is large and its consistency is also large. Therefore, the size of the ink concentration determines the depth of the hue of the ink. When the ink concentration is large, the printing hue is deep; on the contrary, the printing hue is shallow. The ink with high concentration consumes a relatively small amount of ink in printing, and the quality of the ink is also better. On the contrary, the ink with a small concentration has a relatively large amount of ink used for printing, and the ink is relatively light. The concentration of ink The printing effect is particularly prominent when printing large-area plate products. It can be seen that the ink concentration will directly affect the printing quality of the product. Therefore, when printing fine mesh or thin lines of products, it is generally necessary to use high density ink to print, while printing the product on the ground is appropriate to use a slightly lower concentration. The ink is printed. Because the ink has a "thixotropic" side, when the printing environment temperature is high, the speed of the machine is fast, the ink is heated and thinned, and the concentration of the ink is reduced. This requires printing with a slightly higher concentration of ink, which can better ensure the ink color of the product. quality. Conversely, ink with a slightly lower concentration can be used for printing. If a small concentration of ink is used to print a background color or a stacked color plate, the required printing hue may be obtained by increasing the amount of ink applied to the plate, but this may easily cause the product to suffer from a defect. Based on this situation, the ink used in color printing products generally adopts a proper darkening of its hue, the concentration is also appropriate, the printing effect is better, and it is beneficial to the anti-adhesion of printed products.

Process practice and analysis show that when the original ink is not used, its concentration is constant, but in the course of use, the concentration also changes with the variation of consistency and fluidity. Changes in conditions such as printing speed, temperature, and amount of fountain solution can all affect the depth of the ink. If the printing surface water is too large, the ink concentration will be diluted, making the ink appear pale. It can be seen that the ink concentration is a variability factor that affects the quality of the product's ink color. Therefore, correctly understanding and understanding certain conditions related to the ink density and adopting corresponding technological measures for printing have very important guiding significance for ensuring the printing quality. (Author: Kang Kai)