New metachromatic spectrum ink

Every anti-counterfeit technology, along with the popularity of its application, will increase the possibility of forgeries being forged, and the function of anti-counterfeiting will gradually decrease. Therefore, extending the timeliness and uniqueness of anti-counterfeiting technology has always been the goal of anti-counterfeiting technology. And metamerism ink is a new type of ink with a unique anti-counterfeiting function.

Metamerism: We know that each object has its own fixed optical properties. Under the irradiation of sunlight, the color is fixed, and the inherent spectral parameters of the material are certain, it will not change with changes in external conditions. . Therefore, the spectral data is the only and most realistic description of the object's color.

In the evaluation and description of the color system, the characteristics of the color are often expressed in a three-dimensional coordinate system. That is, the color is described by the three basic parameters of hue, lightness, and saturation. In addition, there is a certain relationship between the reproduction of a color and the characteristics of the light source that observes the color. Some two substances show the same color under one light source, but under another light source, they show different colors. It is called metamerism. For the purpose of standard assessment of this phenomenon, the International Commission on Illumination has introduced a metamerism evaluation index to evaluate the phenomenon of color tube heterotraops.

Metameric overprinting inks: Metameric overprinting inks are developed based on the principle of metamerism of substances. Under the irradiation of sunlight, the two metachromic inks have the same color visual effect, ie, they have the same expression of color characteristics, but the two inks have different spectral properties. Same-color different-spectrum ink is the use of two colors with the same color, different spectral characteristics of the two pigments, to produce two colors with the same effect, and different spectral characteristics of the ink, a pair of metachromatic spectrum of ink. The anti-counterfeiting function of the metachromatic spectrum ink is mainly determined by the different absorption and reflection ability of the pigments in the ink that play a role of coloration.

The same-color different spectrum ink has obvious anti-counterfeiting effect and is easy to observe; because it needs special pigment series to produce, it has better anti-counterfeit security; the same-color different spectrum ink has good durability and stable performance, unlike the fluorescent ink, which has a problem of the decay cycle. After a certain period of time, the color rendering characteristics will not change.

There are two methods for observing and discriminating metachromatic inks that are suitable for use as security inks. One method is that, according to a pair of metameric spectrum inks having different spectral characteristics, that is, having different spectral characteristics, the spectra of the two inks can be measured by the instrument and compared. The second method is simple and easy. It is based on the principle of selective absorption and reflection of light by ink, so that a pair of inks passes through a specific color filter, and one of the inks causes a change in the reflected light due to the role of the color filter. At the same time, the ink still absorbs and reflects the original light after passing through the color filter, and the displayed color does not change. In this way, we can identify the true and false of the subject matter through two fixed, different colors.

application

The use of the same-color different-spectrum inks is mostly offset printing, which can be used to print or normal printing. The two inks should be printed on the adjacent parts of the substrate to facilitate observation and comparison. And different-color different-spectrum inks can be combined with infrared inks to achieve better anti-counterfeiting effect. The combined anti-counterfeit feature is that, under the illumination with a spectral wavelength of 600 to 1000 mm, the visual effects of the two are consistent, an ink is colored under infrared irradiation, and an ink absorbs infrared light to show a colorless state, and the spectral characteristics of the two are also not In the same way, this can achieve double anti-counterfeiting effect.

In foreign countries, the same-color different spectrum ink has been used for printing money. At present, there is no practical application in China. It needs to further understand it and exert its anti-counterfeiting effect.

Source: China Ink Technology Network