In the process of printing on the aluminum foil film, the main problem is whether the printing is clear and accurate without falling off, so the requirements for the ink used are particularly high, whether it is a traditional solvent ink or a new environmentally friendly water-based ink. , adhesion, gloss, drying and printability are key considerations. Composite packaging bags, aluminum foil bags, special inks for plastic packaging bags Printing suitability analysis The main component of aluminum foil film is metal, with high molecular density and poor adsorption, so it cannot fully absorb ink and moisture like paper, and can only increase the pressure to make The surface of the printing plate and the aluminum foil are in contact with the largest area to improve the adhesion of the ink, and then the water is evaporated through the drying system of the printing equipment, and the oxide conjunctiva is dried. This requires strong ink adhesion and fast drying. Due to high temperature drying, not only the ink binder and pigment are required to have high heat resistance, but also the ink is required not to fall off and not change color during printing and heat sealing. Gravure ink is a liquid ink, and viscosity is one of the important indicators to measure the rheology. The viscosity is usually expressed by measuring the outflow time of the ink by a viscosity cup. Ink viscosity is closely related to transfer rate, adhesion, and color. Under normal viscosity, the ink in the cells is transferred well, and the dots of the printed product are not exposed or smeared. When the viscosity is low, the resin and pigment components in the ink are relatively small, and the gloss of the printed product is poor; Quality problems such as flying ink; when the viscosity is too large, the ink is in a supersaturated state, the pigment is unevenly dispersed, agglomerated and accumulated, and the fluidity is deteriorated, causing scratches, white spots, loss of small dots, blockage, and color phase change of printed products. Shallow problems. Solvent-based ink performance analysis Most of the solvent-based ink binders are commonly used chloric acid resins and acrylic resins. These resins can provide good adhesion and good heat resistance, and have bright color, high concentration, strong adhesion and transparency. good. The disadvantage is: in the printing process, the amount of solvent volatilization is large, which is not environmentally friendly, which endangers the health of the relevant staff, and it is easy to cause the ink to deposit and dry in the gravure cells, causing paste printing. Therefore, it is necessary to stir the ink or increase the temperature of the ink in a warm water bath. Necessary pretreatment is required for deposition and freezing, and the ink viscosity is usually controlled in the range of 17~26s (25 ℃, 4# viscosity cup). Performance analysis of water-based ink The environmentally friendly liquid ink made of water as solvent has the characteristics of non-toxic, non-irritating odor, non-flammable, stable, bright color, non-corrosive printing plate, and good adhesion after printing. Water-based ink pigments are required to have strong alkali resistance, good dispersion, high saturation, good wettability, and no discoloration and fading. The comparison of printability shows that the performance of water-based inks basically reaches the level of solvent-based inks, and even some properties exceed solvent-based inks. For example, water-based inks of polymer emulsions replace 30%~70% of traditional solvent-based inks. It is an organic solvent, so it is not easy to volatilize during the printing process, has no adverse effect on the health of the relevant staff, and will not cause pollution to the atmospheric environment. However, there are also disadvantages such as high drying energy consumption, low drying efficiency and poor drying performance of ink.
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