Common problems and solutions of water-based ink printing

The printing industry is also gradually transforming to green and sustainable development, and green printing has become the main direction of the development of the printing industry.

Water-based ink uses water as the main solvent, and does not emit volatile organic compounds (VOCs) during the printing process. It is a relatively environmentally friendly printing ink. It is often used in the packaging and printing of products with strict national requirements such as food packaging.

However, because water-based inks use water as the main solvent, they also bring some problems to their application during the printing process.

Today, the editor will take you to understand the problems that may occur in the printing process of water-based inks and the corresponding solutions.

01 gelation

Phenomenon: Due to improper storage or improper use of ink additives and solvents, the ink loses its fluidity and solidifies into a gel.

Solution: Keep the ink tightly closed in a cool and ventilated environment, and use special auxiliary additives and solvents. In addition, it is also necessary to check whether other inks are leaked, and different inks must be strictly confirmed before use.

02 Outline blur

Phenomenon: The high-profile part of the printed product is blurred, the dots are blurred and the tone is lost. The quality of the printing plate is not high, the contact between the printing plate and the ink roller is too tight, the viscosity of the ink is large and the ink is thickened, the ink dries too fast and the stirring is poor.

Solution: The pad should be adjusted evenly and evenly to adjust the printing pressure. When adjusting the viscosity of the ink, the water and alcohol should be mixed reasonably and stirred evenly, and the ventilation device should be adjusted. Do not blow on the ink roller. And increase the machine speed to scrub with water containing monoethanolamine or add 0.2% dimethyl silicone oil or increase the proportion of coupling agent.

03 light ink color

Phenomenon: The ink color is light and cannot reach the ideal color concentration. It is mainly manifested that the ink color concentration of the printed graphics and text on the cardboard is lighter, the tone is dim and not bright, which is mainly caused by the unsatisfactory viscosity of the ink. If the viscosity is too low, the original ink should be replaced or remixed.

Solution: The ink should be fully stirred before use. If the ink quality is found to be poor, the good ink should be replaced, and the ink transfer effect should be checked. wax like polyamide for good adhesion of ink If the transfer is not good, check the roller, printing plate and cardboard and other factors.

04 Ink foaming

Phenomenon: Too many water-based ink bubbles will cause white spots, sand holes, water marks and other phenomena on the surface of the printed product. Mainly due to insufficient ink circulation, too much water, too much pump circulation, and too little air leakage in the tube.

Solution: Appropriately add defoamer (0.2% or mix both internal and external plasticizers and defoamers) to reduce the circulating volume of the pump and replenish new ink, so that it does not dilute the inspection tube excessively and prevent air leakage.

05 Poor drying

Phenomenon: The graphics and texts of the printed matter are poorly dried, too fast or too slow. The viscosity of the main water-based ink is too high, the edge of the edge is enlarged, the drying of the water-based ink is poor, and the paper absorption is poor.

Solution: first check whether the drying of the ink is suitable, it is best to use fast-drying ink; check whether the viscosity of the ink is too high, if the viscosity is too high, further dilute the ink; check the absorption performance of the cardboard, if the absorption performance is too high If it is poor, it is necessary to replace the cardboard with good absorption; check whether the edge of the imprint is enlarged. If the expansion is caused by improper printing pressure, the printing plate pressure should be adjusted or a new printing plate should be replaced.

Although there may be some problems in the printing process of water-based ink, it is the product of the development of green printing and is a relatively environmentally friendly green printing ink.