Precautions for the most popular transparent ink p

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Precautions for transparent ink printing

transparent ink refers to the ink made of dyes with all or most of the colorants, which has low coverage and high transparency. This article talks about some matters that should be paid attention to in the use of transparent ink

1. Hue Jinan experimental machine factory hardness tester definition

due to the high transparency of transparent ink, aluminum coating is generally compounded after printing, so that the gloss of aluminum film and the gloss of ink are combined, reflecting bright colors. Moreover, for products printed with transparent ink, the color phase will change significantly from different angles, and the difference will be greater when observed under different light sources. Therefore, when preparing this kind of ink, we must understand what materials the customer compounded, so as to prepare the ink according to the same process, and observe the hue of the ink in 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, although there is a certain gap between the hue of some inks after printing and the standard sample, the hue after compounding is closer to the standard sample. The hue allocation of transparent ink is very laborious, so it is very important to know the process of customers

2. Transparency

the transparency of transparent inks is determined by dyes (pigments) and binders (including additives), and the former plays a major role, while the latter has little influence. For the inks made of polyurethane, polyamide and chlorinated polypropylene, the transparency of polyurethane inks is high. Generally speaking, the transparency of inks with dyes as colorants is higher than that of inks with 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

3. Residual solvent and odor

careful operators will find that the drying speed of transparent ink is significantly slower, because the size of the change angle of transparent ink is abetted by the scale line on the movable chuck. The solid content is low (because the dye has a higher color concentration than the pigment, so the dosage does not need to be too much), and the solvent content is high, so the drying condition needs to be controlled, otherwise it is easy to cause the residual solvent to exceed the standard and produce odor. In serious cases, the compound solvent will slowly penetrate and diffuse around, causing other colors to change color. Therefore, when printing this kind of transparent ink, we must pay attention to the control of solvent ratio and printing speed, and then put it into a curing room at about 40 ℃ for more than 10 hours after printing

4. The dissolving of the adhesive to the transparent ink

the dye used in the transparent ink is completely soluble in organic solvents, so when the print comes into contact with the composite adhesive, the solvent in the adhesive will dissolve the transparent ink on the print more or less. Increasing the compounding speed or increasing the viscosity of the adhesive can alleviate this problem to a certain extent, but it is only a symptom rather than a root cause. In addition, if the transparency is allowed to be reduced appropriately, some pigments can be added to the dye to produce transparent ink, which also improves the dissolution of transparent ink. In addition, in view of the above problems, some ink factories have developed transparent inks that are completely insoluble in alcohol soluble adhesives and cannot have slippage, and have been well applied to some printing materials. It is believed that transparent inks that are insoluble in ester soluble adhesives will also be developed in the future

5. Peel strength

penetration is a normal life experience. The problem of poor peel strength often occurs in the composite aluminum coating of products printed with bright ink. Why is this? In fact, it is not just the transparent ink that has this problem. When printing with other inks, if the white ink substrate is not printed, the phenomenon of poor peel strength will also appear after the composite aluminum coating (especially VMCPP), but this process is rarely used when printing with other inks, so the phenomenon of poor peel strength is rarely found. Of course, not all composite inks have this problem

in addition to the above characteristics, the leveling property of transparent inks is generally very good, and there is almost no knife line problem during printing.

source of information/Greater China Printing

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