Ink And Aluminum Film Printing Applicability

In the current high-end packaging cartons, in order to improve the effect of packaging printing, it is often necessary to improve the surface brightness of the packaging box. A common practice is to use special papers, such as gold and silver cardboard, to print on such papers, rubber rollers. In order to obtain higher gloss, it is often necessary to use transparent ink for printing. Next, the author discusses the printability of the transparent ink.

Characteristics of transparent ink: Transparent ink is an ink made by all or most of the colorant using a rubber roller dye, which has low hiding power and high transparency.

Hue: Due to the high transparency of the transparent ink, the aluminum alloy film is generally composited after the rubber roller is printed, so that the gloss of the aluminum film and the gloss of the ink are combined to reflect a relatively bright color. Moreover, products printed with clear inks will have a more pronounced change in hue from different angles, and the difference will be greater under different light sources. Therefore, when formulating such inks, it is important to understand what materials the customer is compounding in order to mix the inks in the same process and observe the hue of the inks in a similar environment. For example, some hue before ink compounding is very close to the standard, but the hue after compounding may be very different; on the contrary, some inks have a certain color difference after printing, but the hue is closer to the standard after compounding. The hue blending of the rubber roller transparent ink is very laborious, so it is very important to know the customer's process.
 
Transparency: The transparency of a transparent ink is determined by two parts: the dye (pigment) and the binder (including the auxiliary), and the former plays a major role, and the latter has little effect. Polyurethane inks have higher transparency in inks made from common resins such as polyurethane, polyamide, and chlorinated polypropylene. Rubber Rollers In general, inks with a dye as a colorant have a higher transparency than inks with a pigment as a colorant. Sometimes, due to other needs, some pigments are also mixed in the dye, and the transparency of the ink is lowered.

Residual solvent and odor: Careful operators will find that the drying speed of the transparent ink is obviously slower. The rubber roller is because the solid content of the transparent ink is low (because the dye has a higher color density than the pigment, the amount does not need to be too much), the solvent The content is high, so it is necessary to control the drying condition, otherwise it will easily cause the residual solvent to exceed the standard and produce odor. In severe cases, the solvent will gradually permeate and diffuse around the composite, causing discoloration of other colors. Therefore, when using such a transparent ink, it is necessary to pay attention to the control of the solvent ratio and the printing speed. After printing, it is aged in a curing chamber of about 40 ° C for more than 10 hours.

Dissolution of transparent ink by adhesive: The dye used in transparent ink is completely soluble in organic solvent, so when the printed matter comes into contact with the composite adhesive, the solvent in the adhesive will be transparent ink on the printed matter. More or less dissolved. Increasing the speed of compounding or increasing the viscosity of the adhesive can alleviate this problem to a certain extent, but it is only a temporary solution. In addition, if the transparency is allowed to be appropriately lowered, a part of the pigment may be added to the dye to produce a transparent ink, which also has a certain improvement in the problem of dissolution of the transparent ink. In addition, in response to the above problems, some ink factories have developed transparent inks that are completely insoluble in alcohol-soluble adhesives, and have been well applied in some printing materials. It is believed that insoluble ester-soluble rubbers will be developed in the future. Clear ink for adhesives.

Peel strength: A product after printing with a transparent ink often has a problem of poor peel strength in a composite aluminized film. Why is this happening? In fact, it is not only the problem of transparent ink. When printing with other inks, if the white ink substrate is not printed, the peeling strength will be poor after the composite aluminized film (especially VMCPP), but usually This process is rarely used when printing with other inks, so the phenomenon of poor peel strength is rarely found. Of course, it is not that all composite inks have this problem.