Temperature change printing ink

When the temperature change ink printed packaging product changes at a certain temperature, its color also changes, not only has the decorative effect of ordinary color ink, and its wonderful changes give people magic-like fun, and its regular repeated changes. Can represent the temperature of the environment, but also has anti-counterfeiting features carrying confidential information. Although the price of the temperature change ink is much higher than that of the ordinary color ink, because the actual area of ​​the printed mark is very small, in order to increase the need to protect the name brand products from counterfeiting and counterfeiting, the number of temperature change inks on the market is still increasing. In order to better play the application function of the temperature change ink, this article gives a brief discussion on the ink composition and influencing factors produced by the reversible temperature change pigment for the reader's reference.

The temperature change ink consists of four parts, including a temperature-varying pigment that provides color, a film-forming resin binder, and a solvent and additive additive. To make good use of it, we must understand the factors that affect the effect of temperature change ink printing from the beginning to the end. We have a unified and coordinated control of the temperature change ink from the composition to the production process and printing methods. It is necessary to realize that the reversible temperature-change pigment is the decisive factor of the temperature change function, which is related to the stability of the temperature change ink, the level of the discoloration temperature, the speed of the discoloration, and the degree of sensitivity (the size of the temperature difference interval during discoloration, and whether the discoloration effect is significant ), that is, to recognize the vital importance of selecting pigments, but also to see that the same pigment is affected by other factors, there will be different printing temperature effects, and control of other influencing factors. At present, it is a pity that the color intensity of reversible temperature-change pigments is usually relatively low, and the structure itself is subject to large changes in external conditions. In this way, it is not possible to look only at the surface color, but rather to select a temperature-change pigment that is better able to withstand external light, vapor erosion, and resistance to high temperature damage. Ignoring this point will often result in a dim recession or even complete fading.

When selecting the tree finger and auxiliary agent, it is necessary to adapt the packaging printing method to achieve the different design goals of color shade, and to select materials with good adhesion, color-extensible coated pigment and stable physical and chemical properties. Under normal conditions, the temperature of the warm discoloration generally increases as the number of trees increases. For a gravure temperature ink ratio, if the resin is excessive, the proportion of the pigment will naturally decrease, or the ratio of the solvent in the system will decrease, the viscosity of the system will increase, and the printing adaptability will deteriorate.

The solvent was originally chosen to dissolve the resin, immerse the surface of the substrate, regulate the evaporation speed, and the ink viscosity is suitable for the printing speed, but at this time it must be taken into account that the structure of the temperature-change pigments cannot withstand the reporting solvents such as ethanol and isopropyl. Corrosion of alcohols, ethyl esters and other solvents, so do not choose this solvent preparation and storage, otherwise, during use and storage, temperature change pigment structure and temperature change function will be destroyed, but if it is with the use, the effect will be a little better. The influence of inappropriate solvent on temperature-change pigment ink can be shown in Fig.1: A indicates that the solvent containing ester alcohol is a few days later; the temperature-changing ink shading is light; B indicates the temperature-changing ink prepared on the same day (the same pigment concentration ) Scraping bright red color.

In the degree of production, high-temperature and long-term grinding operations should be prohibited. Otherwise, the structure of the temperature-change pigments will be damaged, and the discoloration effect will be greatly impaired.

The same kind of temperature-change pigments have been used for gravure printing, and the temperature-changing property is still relatively good, but when it is replaced with offset printing, it is not so good. Although some printing processes also satisfy the printing requirements for the adhesion strength of printed products, they have neglected the effective control of the factors affecting the temperature discoloration effect. The higher the temperature, the longer the drying causes all the temperature-changing functions to be lost. These phenomena tell us that temperature change performance is also related to the influence of printing and postpress processing. For this reason, for temperature-sensitive color-changing pigments, it is advisable to use UV-curing instant curing drying techniques, such as flexographic printing with UV inks, screen printing. Screen printing is an important printing method for temperature change inks. It has a thick film layer, a prominent three-dimensional impression, bright colors, novel text changes, and full and lasting temperature change characteristics.

In order to increase the color intensity of the temperature-change ink during gravure printing, it is appropriate to make the depth of the plate-making dots deeper, 40-50 μm, 150-175 lines, and 45°-tilt. Experiments show that the addition of a small amount of other inks can make the temperature change ink more perfect, making a multi-functional anti-counterfeiting ink, and having a better anti-counterfeit use. As shown in Figure 2: A shows that the low temperature shows a reddish yellow color and changes to yellow when touched by hand; B indicates that the medium temperature color shifting ink is >5°C yellow, <50°C is golden yellow, and if illuminated with fluorescence, it will emit red light.

For the general plastic film printing is best made into a composite type, but the first printing ink temperature and then print another color ink, so that color layer can be a certain degree of protection, printing products are also bright and beautiful.

In general, the main conclusions of the temperature change ink packaging printing is that the ink has good sensitivity to temperature change, stability and print adaptability; the best printing method and process; avoid the high temperatures caused by various processes, especially long time high temperature With light damage to temperature change effects.

Reprinted from: Paper Drunk Square