Six common problems and solutions in water-based gravure ink printing

Water based intaglio ink is one of the environmental friendly printing inks in Z today, and it is also the only printing ink recommended and approved by FDA, which can be used in direct contact with food. In China, although the water-based ink for paper printing has been commercialized, it is still in the initial stage of research because of the non absorption disadvantage of the film, which is widely used in the printing of plastic film for food packaging.

On the basis of maintaining the same printing quality as solvent based inks, a good water-based intaglio printing ink must achieve zero VOC emission; Must have good printability; Be able to print on the surface of various substrate materials; At the same time, we also hope that the cost of this kind of printing ink is relatively low. Using water-based gravure printing ink will cause problems such as changing the engraving of gravure printing roller, changing the operation of printing machine, maintenance of printing machine, replacement of dryer and so on. Similarly, the substrate material will also strongly affect the printing effect of ink, especially for the substrate with low surface tension, such as plastic film material and coated paper surface printing.

For uncoated paper, ink may even lead to paper deformation and curl. These problems do not exist for solvent based gravure printing ink. Importance of pH value of water-based gravure printing ink: compare water-based and solvent based gravure printing ink. In the process of scraping excess ink from the gravure printing ink hole by the doctor blade, the gravure printing process using solvent based ink should minimize the evaporation of solvent. After the stamping process is completed, the ink is transferred to the substrate material, and then slowly form an ink film, In this process, the solvent in the ink must complete the evaporation process before the ink film adheres, so as to quickly dry the ink film.

In water-based ink, the organic solvent is replaced by a certain percentage of water, cosolvent and volatile amine, which is necessary to neutralize the acidic resin. Due to the slow volatility of water, there is no problem of evaporation and drying of ink in the inking hole of the printing plate, but there is a problem of drying after printing. Therefore, the selection of amines in ink and the adjustment of pH value are as important as the control of ink viscosity.

Because the premature release of amine solvent before the completion of the embossing process will lead to the decline of pH value, causing the resin to dry in the inking hole of the gravure printing roller. In addition, water and cosolvent systems cannot re dissolve the resin, which is different from solvent based inks. Therefore, it is impossible to re dissolve any possibility of pH decline. In gravure printing, we should be very careful to control the pH value, because the decline of the pH value of the ink causes the inking hole to be slowly blocked until it is completely blocked, which is a very serious problem, which will lead to the inability of the printing operation to continue.