In plastic printing, the viscosity of the ink has a great influence on the printing quality. By adjusting the viscosity of the ink, the printing effect can be effectively improved.
1. Hue
Reducing the viscosity of the ink to lighten the color, and vice versa. But you can't just adjust the viscosity to change the color, otherwise there will be other problems, such as water lines, color no gloss and so on. In the color adjustment, it is necessary to grasp the variation of the viscosity of the different colors in order to make better use of the viscosity. For example, when the primary yellow color has a large viscosity, there is a side that is biased toward red, and when the viscosity is small, green color appears; the green viscosity is large and the blue phase is small, and the viscosity shows a yellow phase.
2. Watermark
This problem is also generally closely related to the printing speed. The lower the printing speed, the greater the required ink viscosity, and vice versa. If the speed and viscosity do not match well, watermarks are likely to occur. Usually the printing speed is basically fixed, so the water lines are solved by increasing the ink viscosity. Another phenomenon is very similar to the water pattern. If you do not carefully observe and analyze it, it is easy to solve it like a water mark. To solve it with increasing viscosity, the result is not effective (or the opposite effect). This is something that many people will Ignored. I have personally contacted many printers and they often make mistakes. The difference between the water pattern and this phenomenon (temporarily called "flower") is that the watermark shows a very short and short line, while the "flower" shows a round dot. The solution is to reduce the viscosity of the ink, if it is too serious, it may be a problem with the quality of the printing plate or the ink. By adjusting the viscosity, the effect is only improved.
3. Cutting line
Smaller ink viscosities can prevent knife lines from appearing to the maximum. Especially when printing in gradation printing, these cutting lines are not printed, or are very small. There is also a case where the cut lines appear in the meshed position and they are all at the starting point.
4. Squeegee effect
The viscosity is large and the effect of squeegeeing is not good (it means that the squeegee is not clean), especially for the black ink, generally a smaller viscosity is used to prevent the squeegee from being clean.
5. Overprint fault
Including two cases: one refers to the latter color of the ink dissolved in the previously printed color, so that discoloration or smearing, ghosting, at this time should increase the ink viscosity of the latter color; the other case is the latter color Ink printing is not on the previous color ink. At this time, the viscosity of the ink of the latter color should be adjusted.
6. Ink transfer
When printing shallow webs, smaller viscosities are beneficial to improve ink transfer and avoid undesirable "white spots". As can be seen from the above, viscosity has a close relationship with many printing problems, and mastering the adjustment of viscosity can solve many problems. (Author: Wear Spring Unit: Mika Ink Co.)
Source: "Guangdong Printing" No. 1 2005