Self-fading magic ink

In today's diversified security and anti-counterfeiting measures, various new types of anti-counterfeiting technologies emerge in an endless stream, presenting a flourishing situation. The key to an anti-counterfeit technology is to extend the timeliness and uniqueness of anti-counterfeiting technology, which is also the goal of anti-counterfeiting technology. The anti-counterfeiting technology mainly includes: anti-counterfeiting of printing design, anti-counterfeiting of printed paper, anti-counterfeiting of printing ink, and anti-counterfeiting of printing process. Among them, the development of printing ink anti-counterfeiting technology is very good, and its application is becoming more and more extensive.

1. Anti-counterfeiting principle of achromatic ink

The so-called anti-counterfeiting ink is a special printing ink that is made by adding a special performance anti-counterfeiting material to the ink connecting material and processing it through a special process. Anti-counterfeiting inks are mainly divided into the following types according to their anti-counterfeiting functions:

1 magnetic security ink

2 Fluorescent inks and phosphorescent inks

3 reaction color change ink

4 anti-printing ink

5 Daylight Induced Color Change Ink

6 smart security ink

7 infrared ink

8 nanometer ink

Among them, reactive color-changing inks are an important part of anti-counterfeiting inks, which can be further divided into thermochromic inks, photosensitive color-changing inks, humidity-sensitive color-changing inks, and pressure-sensitive color-changing inks. Reactive color-changing ink is a variety of chemical substances added to the ink, under certain conditions (such as light, heat, humidity, pressure, etc.), can produce a variety of chemical reactions, so that the ink changes color, to achieve anti-counterfeiting purposes. Achromatic inks are a branch of reactive color-shifting inks, which are inks that readily discolor or dissolve when exposed to water or chemicals.

2. Classification of achromatic ink

1 water achromatic ink

Water decolorizing ink is also called moisture sensitive ink. The principle of anti-counterfeit is that the color material contains substances whose color changes with the change of humidity. Water or bleach can make them decolorized. Generally, they are water-soluble substances containing oxidants or reducing agents. The anti-counterfeiting feature is that the dry state is colorless, and the wet state becomes colored. Water achromatic ink is divided into reversible achromatic, irreversible achromatic, moisture-sensitive diffusion of three, with blue, green, black, red four colors.

● Reversible achromatic ink The color of the ink changes from colored to colorless. After the water droplets are volatilized, the original color is restored. The color is from white to none. It can only be screen printed and gravure printed. If screen printing is recommended with 200 mesh screen printing, the thicker the better.

● Irreversible Achromatic Ink: It is an oil-based ink. It changes from colored to colorless after dripping. After the droplet evaporates, the color no longer returns to its original color. The color is black → none, red → none, blue → none, and green → none. Only screen printing, gravure printing, requiring a thin print, bright colors, good fade effect, such as screen printing recommended 350-420 mesh screen printing.

● Humidity-sensitive diffusion is irreversible, and the colors are red, yellow, blue, green, etc. Only water-based screen printing can be used.

2 organic solvent achromatic ink

For example, alcohol, gasoline, benzene, etc. The principle of organic solvent discoloration and water discoloration is fundamentally the same, and they are discolored according to the interaction of the corresponding chemical substances.

3 composite achromatic ink

The combination of water-reduced inks and organic solvent-based achromatic inks can be called composite achromatic inks. Composite achromatic inks can react with aqueous solvents, bleaches and organic solvents to achieve the purpose of achromatism. In general, a weak bleach can remove the stamp and water-soluble pen ink on the passport. In order to remove all or part of the ballpoint pen ink, organic solvents can be used. However, these solvents are also not likely to have an effect on all printing and pen inks. Among them, black ink is based on carbon. General solvents do not eliminate them. The composite achromatic ink is a manifestation of the development trend of the anti-counterfeiting ink, because the composite anti-counterfeiting ink can not only prolong the service life of the anti-counterfeiting ink, but also can improve the anti-counterfeiting effect.

4 binary security ink

Dual anti-counterfeiting ink, which means that the achromatic ink contains fluorescent components, it can easily be resolved into the use of solvents under the irradiation of ultraviolet rays. Correspondingly, some of the faded inks contain a visible fade component and have a permanent fluorescent component. Under visible light irradiation, these inks do not seem to exist at all, but when exposed to ultraviolet light, they can be observed by the human eye. Many printing inks lose their fluorescence when they are bleached. Therefore, we can use fluorescent ink as a feature to check whether it has been bleached or not, and use a machine for inspection.

3. Application of achromatic ink

At present, water-reducing inks are the more commonly used inks, often used as the background for document signatures, and are used below the easily-correctable numbers that are filled in. In addition to the bleaching ink as the background color, when the substrate is bleached, chemical reactions may occur to cause brown spots. In documents that need to be identified, such as photographs on a passport, the laminate is laminated between the substrate and the foil used for the wrapping material. The water-miscolored ink is printed on the inner surface of the foil so that it can be detected whether There is the existence of water.

Many water-repellent signs are those that are printed with water-reducing ink, and are affixed to a part of the main body of the mobile phone or outside the battery. When the logo is not exposed to water soaking or moist gas, the edges of the graphic are clear and will not fade or change color. After encountering water, there will be color diffusion at the edge of the graphic and it cannot be restored. It can be used as an identifier for the transportation, preservation, and use of electronic devices and other products. At present, many mobile phone manufacturers use this high-quality waterproof logo. This kind of logo can also adjudicate some claims issues and provide corresponding scientific evidence.

In short, due to the increasing level of counterfeit and counterfeiting of tickets and product trademarks, and the large number of counterfeit goods, the new anti-counterfeiting technology has been promoted, and it is required to quickly, cheaply, and accurately reveal the authenticity of the object being protected, in which the anti-counterfeiting ink plays an important role. The role. Achromatic ink also came into being. Although the current achromatic inks have been greatly developed and applied to life, due to the problems of preparation and inspection of achromatic inks, they cannot be applied to any field as widely as other inks. However, as the technology continues to advance, many difficulties will be solved. We believe that this very easy to use anti-counterfeiting method will become an important part of anti-counterfeiting technology.