Four technical indicators should be paid attention to in the application of water-based ink-Corrugated Display Boxes Of Clothing

Four technical indicators should be paid attention to in the application of water-based ink-Corrugated Display Boxes Of Clothing

In China, since flexographic printing has only emerged in recent years, printers either use inertial thinking methods or do not know where to start when controlling ink and wash. The result is often a waste of a lot of human, material and financial resources, and heavy losses . Therefore, it is particularly important to correctly understand the technical control indicators of ink and wash. This article will discuss several main technical indicators such as viscosity, PH value, thickness and dryness of flexographic ink.

Viscosity

Viscosity is a property that prevents fluid flow, and is a measure of the ability of fluid molecules to interact with each other to hinder the relative motion of their molecules, that is, the resistance of fluid flow.

Viscosity is the most important control index in ink application, because it directly affects the transfer performance of ink and the quality of flexographic printing. The viscosity is not only related to the viscosity and density of the resin in the binder, but also to the type and particle size of the pigment. In printing, low viscosity ink transfers quickly, which will cause light color, large dot expansion, high gloss dot deformation, uneven ink transfer, etc.; high viscosity, slow ink transfer, it will affect the transfer performance of the anilox roller, resulting in ink color Unevenness, sometimes not deep color printing, dirty version, paste version and other drawbacks.

If the viscosity is low, it can be adjusted by mixing it with new ink; and if the viscosity is high, it can be diluted with water or water and ethanol (50% each), or it can be adjusted with an ink stabilizer. In addition, in the printing process, the temperature also has a great influence on the viscosity of the ink. Usually, the viscosity decreases when the temperature increases, and vice versa, the viscosity increases. So, in Corrugated Display Boxes Of Clothing

During the printing process, in order to keep the density of the printed products consistent, the temperature of the printing workshop should be kept constant.

pH value

The binder used in ink is mainly alkali-soluble acid resin, so the control of PH value is very important. Usually the PH value should be controlled between 8.5 and 9.5. At this time, the printing performance of the ink is the best, and the quality of the printed product is the most stable.

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During the printing process, it is constantly volatilizing, and the operator has to add new ink and various additives from time to time, so the PH value of the ink is changing at any time. When the pH value of the ink is higher than 9.5, the alkalinity is too strong, and the viscosity of the ink will decrease, resulting in slower drying speed and poorer water resistance; when the pH value is lower than 8.5, the alkalinity is too weak, and the viscosity of the ink will increase. High, resulting in faster drying speed, easy to block the printing plate and anilox roller, cause the layout to be dirty, and will generate air bubbles.

Since the effect of PH value is directly related to viscosity, it is recommended to use Corrugated Display Boxes Of Clothing in actual Corrugated Display Boxes Of Clothing

Linking the two to control in printing, especially in the process of color printing, should pay more attention to this problem. Usually in addition to the viscosity cup, a simple pH indicator should be prepared for testing at any time. When the pH value of the ink is low, a pH stabilizer or a small amount of alkaline substances can be added; when the pH value is high, a solvent or diluent can be added for dilution.

Thickness

The so-called thickness of ink refers to the degree to which solid powdery substances such as pigments and fillers mixed in the linker are dispersed.

The thickness of the ink is also a very important quality indicator, because it is not only related to the application properties of the ink (including tinting strength, hue, stability, etc.), but also to the rheological properties and economic benefits of the ink. If the ink is too thick, it will cause problems such as accumulation of ink and paste, and the tinting strength and hue of the ink will also deteriorate; if the ink is too fine, the fluidity will be great, and it will flow after printing. This flow will cause the dot to expand and affect print quality. In addition, the thickness of the ink will also affect its dispersion. When the dispersibility of the ink is not ideal, its printing performance will not be satisfactory, and the surface of the printed matter is not smooth, smooth and soft, and it will produce a "block" feeling, thus greatly reducing the printing effect.

In actual printing, inks of different thicknesses can be selected according to specific requirements. When printing the prints with finer screen lines and higher precision, the fineness of the ink is higher; when printing the prints or solid prints that do not require very high precision, the thickness of the ink can be appropriately reduced, which is also for the purpose of Reduce costs and improve economic efficiency.

Dryness

The dryness of the ink is a very important technical indicator. The drying speed of the ink is not only related to the performance of the ink itself, but also related to the printing speed, the drying capacity of the drying equipment and the performance of the printing material. This article only considers the factors of the ink itself.

The principle of selecting ink drying is usually: the ink should be able to perform the next Corrugated Display Boxes Of Clothing under the existing conditions of the printing machine.

Dry well before printing and before rewinding or stacking, but not on the plate.

Ink uses water as the solvent and alkali-soluble acid resin as the binder, which is mostly used for the printing of corrugated boxes and paper bags. Therefore, the drying form is mainly infiltration drying and a small amount of volatilization drying. Since water is used as a solvent, its volatilization speed is lower than that of other solvents, so the drying of ink is slower than that of solvent-based ink. Therefore, a small amount of alcohol is usually added to the solvent to improve the drying speed of ink. In addition, under the condition that the solvent is determined, the selection of different types of resins also affects the drying properties of the ink. Because different resins have different curing speeds on the substrate and different release characteristics of the solvent, the drying properties of the ink are also different.

In practical applications, the dryness of the ink is also related to its viscosity and PH value. The ink is dry but the viscosity may be too high, which can be solved by further dilution; the ink dries quickly, and the pH value may be lower than 8.5, which can be adjusted by adding a stabilizer. In addition, a fast-drying agent or a slow-drying agent can be added to the ink according to the actual printing speed, and the drying speed of the ink can be appropriately changed to obtain a stable printing effect. The amount of fast-drying agent or slow-drying agent is generally 1% to 2% of the total ink volume.

There are still many quality indicators that need to be controlled in ink application. In addition to the main indicators mentioned in this article, they also include: color, gloss, adhesion, and stability. In actual Corrugated Display Boxes Of Clothing

In printing, in order to comprehensively improve the printing quality, various indicators should be considered comprehensively.