Flexible flexo printing ink

Flexographic Printing Water-Based Inks for pH and Viscosity Control Today, most flexible flexo printers understand the color matching of a color. The entire water-based ink must be used while maintaining a certain viscosity. In the laboratory, detecting the viscosity is the most common task for the operator each time using the Zahn Cup and the meter. If the viscosity of the ink is higher than the expected value, some amount of water is generally added. The problem will happen.

If water is used alone to control the viscosity of the ink, each time water is added, the pH of the ink will decrease as the viscosity becomes smaller. The pH of the water is 7, while the pH of the flexographic water-based ink is generally supplied by the supplier, usually between 8.5 and 9.5. When the PH value decreases, the effects of the ink components will begin to change, and the lower PH value will have a significant loss of color intensity. Even more, the ink components begin to separate or split and produce a muddy phenomenon. The same is true for high pH values. It will result in loss of structure and composition.

Today, the PH value is considered to be the most critical factor in controlling the mid-range of flexographic printing. Is pH more important than viscosity? The answer is correct. However, in establishing and maintaining the most suitable inks, the pH and viscosity are inseparable and the two are mutually controlled.

● Use the correct viscosity adjustment fluid
How to control PH value and viscosity? First of all, you must use the PH meter to detect the pH value, understand the pH value of all ink components, additives, and record the changes. Urban water usage may vary by more than one unit at different times of the month. In addition to adjusting the viscosity with water, another pre-mixed adjustment solution can also be used. This adjustment solution contains some amount of amines and other components. Usually the ink supplier provides adjustment solution that can increase the pH of the ink by 1 to 1.5. At this time, water can no longer be used to adjust the ink.

Both the pH and the viscosity are the key to the success of printing. In the setting up of printing, pumps, rollers, measuring systems, printing plates, staple back operations, materials, and drying, the ink has only the best viscosity/ PH value to get the best color. Many letterpress printers have found that colors in contact with each other during overprinting, in-line liners, or color overprinting occur. Therefore, the most useful way to achieve this is to increase the viscosity and decrease the pH, which helps the drying process and avoid post-printing. The color is moistened by the pre-printing color, for example: This method obviously requires more than one kind of adjustment liquid to be added to each ink machine table to adjust the required viscosity. Furthermore, these adjustment fluids must be higher than the pH of each ink by 1.0 to 1.5.

Does the automated system make sense?

In the use of printing ink, the use of automated viscosity/pH control system can effectively detect the stability of the ink on the line, thus reducing the ink film and ink consumption, and at the same time reduce the volatile organic compounds (VOC) (amines, alcohols or The use of other solvents will save the printing industry valuable time and other important tasks.

Today's newer generation of automatic control systems have excellent accuracy and reliability. They can be easily operated and maintained. Both multi-unit or single-unit control systems can be purchased at a lower price than before, and some even provide SPC/ISO report.

Finally, it must be mentioned that, whether using an automated system or manual operation, the most important thing is to adjust the use of liquid, not water.
Description of the drawings
Resilient letterpress printing machine.
BHS--Direct printing cylinder rotation axis