Water-based gravure ink and the resolution of common printing problems (below)

2) Solution

a Water-based inks have a slow drying speed. Therefore, when setting drying conditions, common hot-air type and hot-roller type temperatures should be 20 to 30°C higher than when using solvent-based inks.

b When drying with high-frequency dielectric heating, the electromagnetic wave frequency of high-frequency dielectric heating in the past was 10 to 150 MHz, and a microwave heating drying method using 300 to 30000 MHz is now being developed. This is a better drying method for drying water-based inks without reducing the moisture content of the paper. It also helps to solve the problem of drying when using water-based inks for non-absorbing plastic films.

c The use of preheating to increase the surface temperature of printing paper can also increase the drying speed.

2 levels of poor reproducibility

(1) Cause of failure

Water-based inks are less viscous than solvent inks. Due to the slow drying, the ink in the gravure cells is hardly dry, so that the viscosity of the ink does not increase from after the scraping of the blade to the transfer, and the transfer of the high-profile portion is good. Because the viscosity is low and the dark-tone transfer is poor, the contrast of the levels tends to decrease. Water-based inks also have a certain degree of selectivity for paper. In coating paper printing, the printing effect is good and the gloss of the printed matter is good. However, when printing on gravure paper, the ink penetrated excessively in the dark portion and the ink film density was poor, so the gloss of the printed matter was poor.

(2) Solution

a The tone ratio of gravure is made different from that of solvent type, so that the depth of the center of the plate adjusted to the high light is shallower than that of the solvent type.

b The transferability and permeability of the aqueous ink are close to that of the solvent type ink, that is, the drying speed and fluidity of the aqueous ink are changed to reduce the permeability of the dark tone portion.

3 paste version

(1) Failure reason:

When the water-based ink is printed at a high speed (above 150 m/min), it is prone to stencil printing. Paste plate is a problem often encountered in the use of water-based gravure inks. The main reasons for stencil printing are: a. The water-based ink evaporates and dries slowly. The ink film adhering to the surface of the gravure cylinder is easy to transfer to the paper; b. The ventilation is not good; c. The water-based ink easily affects the surface of the paper, making the paper powder mixed into the ink. The resistance tends to become larger; the re-solubility of the d ink is poor, and the dry ink on the plate will increase the resistance of the blade;

(2) Solution

a improved grinding accuracy;

bInstall the ventilation device

c Increase the squeegee pressure (with it, the life of the squeegee and layout will decrease).

4 dirty

(1) Cause of failure

Ink drying speed is slow, printing speed is fast, ventilation is not suitable for heat.

(2) Solution

Increase the amount of ethanol, slow down the printing speed, increase ventilation to heat

5 bubbles

(1) Cause of failure

Ink replenishment over ink ambassadors

(2) Solution

Appropriately add some alcohol and defoamer, ink should not be adjusted too thin

6 Print folds

(1) Cause of failure

a. Solvent-based inks have a rapid evaporation and drying speed, and have little effect on paper fibers. However, water-based inks have a slow evaporation rate and have a very high permeability to paper. Therefore, the quality of paper has a great influence on the drying speed and the gloss of prints. .

b When the paper absorbs water, the fiber absorbs moisture and expands; when it is dry, it shrinks due to moisture release. The expansion and contraction of the paper caused misprints, sometimes curling, and sometimes wrinkling in dark areas.

(2) Solution

a When selecting the paper, try to select paper with more filler and smaller pulping. Consider synthetic paper.

b add some water properly;

c The quality of water-based inks should be continuously improved, the permeability should be small, and drying should be quick.

Fourth, summary

At present, in gravure printing, there are many aspects of water-based ink that are not as good as solvent-based inks. This is mainly because water-based ink technology is not fully mature. Among them, the drying time is still the most important issue in the application of ink, unless the printer is equipped with enough drying equipment, otherwise the printing speed will be affected. This is also the most important factor affecting the speed of the ink-washing process to replace solvent inks. In addition, the use of inks in alkaline solutions limits the use of inks in highly magnetic environments, and the use of inks in frozen food packaging does not have the durability of solvent inks. Despite the rapid decrease in distance, inks are difficult to apply on many substrates. Very good wetting and printing.

However, gravure water-based ink technology is rapidly developing, I believe some of the current problems will be resolved soon. Nowadays, more and more water-based inks are used in gravure printing, which also makes gravure printing have double advantages in environmental protection and printing quality. With the development of water-based ink technology, gravure printing will be more competitive.