In the current packaging carton, in order to improve the effect of packaging and printing news, it is often necessary to increase the surface brightness of the packaging box. One of the common methods is to use special paper, such as gold and silver cardboard, to print on this type of paper, in order to obtain For higher gloss, transparent ink is often used for printing. Next, the author discusses the printing suitability of transparent ink.

Features of printing transparent ink

Transparent ink is an ink made of all or most of the colorant made of dyes. Its hiding power is very low and its transparency is extremely high.

Hue

Because the transparency of the transparent ink is very high, the aluminum coating is generally compounded after printing, so that the printing gloss of the aluminum film and the gloss of the ink are combined with each other, reflecting a more vivid color. Moreover, the products printed with transparent ink will have a more obvious change in hue when viewed from different angles, and the difference will be greater under different light sources. Therefore, when formulating this type of ink, we must understand what materials the customer compounded, in order to formulate the ink according to the same process, and observe the hue of the ink under a similar environment. For example, the hue of some inks before compounding is very close to the standard sample, but the hue after compounding may be very different; on the contrary, there are some inks that have a certain difference in hue from the standard sample, but the hue after compounding is closer to the standard sample. It is very laborious to adjust the hue of transparent ink, so it is very important to know the customer's process.

transparency

The transparency of the transparent ink is determined by the dye (pigment) and the binder (including additives), and the former plays a major role, while the latter has little effect. For inks made of several common resins such as polyurethane, polyamide, and chlorinated polypropylene, the transparency of polyurethane ink is relatively high. Generally speaking, the transparency of inks using dyes as colorants is higher than that of inks using pigments as colorants. Sometimes due to other needs, some pigments will be mixed in the dye, and the transparency of the ink will be reduced.

Residual solvents and odor

Careful operators will find that the drying speed of the transparent ink is significantly slower, because the solid content of the printed transparent ink is low (because the color density of the dye is higher than the pigment, so the amount does not need to be too much), the solvent content is high, so you need to The drying conditions should be controlled, otherwise it is easy to cause the residual solvent to exceed the standard and produce odor. In severe cases, the solvent will slowly penetrate and diffuse around after compounding, causing other colors to change color. Therefore, when using this type of transparent ink, it is necessary to pay attention to the control of the solvent ratio and printing speed. After printing, it is placed in a curing room at about 40°C for more than 10 hours.