Anti-counterfeiting ink is one of the most important technical branches of anti-counterfeiting technology, involving many subject areas, such as optics, chemistry, electromagnetics, computer technology, spectroscopy technology, printing technology, etc., belonging to a cross-edge discipline. Among them, chemical anti-counterfeiting materials and technologies are the basic technologies of anti-counterfeiting inks, and occupy a very important position in research and application. Ink anti-counterfeiting technology is a highly practical technology in the field of bill anti-counterfeiting, marketable securities and trademark packaging, which can not only meet the requirements of the public's first-line anti-counterfeiting identification, but also meet the identification and supervision of second- and third-line senior experts and management departments Requirements.
1. The concept and type of anti-counterfeiting ink
Anti-counterfeiting ink refers to the ink with anti-counterfeiting effect, that is, special anti-counterfeiting material added to the ink connecting material, and the special ink processed by a special process, which is also composed of three parts: color material, connecting material and ink additives. Anti-counterfeiting ink depends on the special functions of the color material and connecting material in the ink to play the anti-counterfeiting function.
Anti-counterfeiting inks can be divided into relief printing, gravure printing, screen printing, offset printing and water-based flexo printing inks according to the printing form. Anti-counterfeiting ink can be divided into paper ink, iron printing ink, newsprint ink, plastic ink, etc. according to the substrate.
Anti-counterfeiting inks are divided into the following types according to their anti-counterfeiting functions:
â‘ Thermosensitive color-changing anti-counterfeiting ink, the principle is that the color material adopts the substance whose color changes with temperature;
â‘¡Photosensitive color-changing anti-counterfeiting ink, its principle is to add photochromic or photo-activated compounds to the ink;
â‘¢Moisture-sensitive color-changing anti-counterfeiting ink, the principle is to add substances whose color changes with humidity to the color material;
â‘£Pressure-sensitive color-changing anti-counterfeiting ink, the principle is to add pressure-induced color-changing compounds or microcapsules to the ink;
⑤Ultraviolet fluorescent anti-counterfeiting ink, the principle is to add visible fluorescent compound with ultraviolet excitation to the ink;
â‘¥ Infrared fluorescent anti-counterfeiting ink, the principle is to add visible fluorescent compounds excited by infrared light to the ink;
⑦ Anti-tampering and anti-counterfeiting inks, adding substances that have color-changing chemical reactions to the chemical substances used for alteration;
⑧ Anti-counterfeiting ink for visual discoloration, the color material adopts multi-layer interference optical broken film;
⑨ Magnetic anti-counterfeiting ink, the color material of which uses magnetic substances, such as iron oxide and cobalt doped in iron oxide. The characteristics of these anti-counterfeiting inks are to implement different external conditions, mainly in the form of light, heat, spectrum detection, etc., to observe the color changes of ink prints to achieve the purpose of anti-counterfeiting.
2. Types of anti-counterfeiting ink
1. UV fluorescent anti-counterfeiting ink
Special ink that emits visible light (wavelength 400-800μm) under ultraviolet light (wavelength 200-400μm). According to the different wavelengths of the excitation light source, it can be divided into short-wave ultraviolet light excitation fluorescent anti-counterfeiting ink and long-wave ultraviolet light excitation fluorescent anti-counterfeiting ink. Generally, short-wave ultraviolet light excites visible violet anti-counterfeiting printing ink with an excitation wavelength of 254 μm, and long-wave ultraviolet light excites visible fluorescent anti-counterfeiting printing ink with an excitation wavelength of 365 μm.
According to the color of printing ink, it can be divided into two types: colored fluorescent ink and colorless fluorescent ink. The former is to add a compound with fluorescence to the colored ink, the latter is to add to the colorless ink, the graphics printed by the former are visible to the naked eye, the latter are not visible.
The composition of ultraviolet fluorescent ink is mainly phosphor, and there are three main types of commonly used fluorescent materials according to their composition. â‘ Organic fluorescent materials are unsaturated molecules with large conjugates, mostly excited by sunlight, which has poor fluorescence stability and easy oxidative decomposition; â‘¡Inorganic fluorescent materials synthesized by high temperature have good radiation resistance and high stability, but in oily media It is difficult to disperse in medium, the synthesis is difficult, and the water resistance is poor; â‘¢ The chemically synthesized rare earth organic complex is a fluorescent material and is the main material of anti-counterfeiting ink. Commonly used organic rare earth complexes are simple to prepare, easy to disperse, dissolve, and refine in oily media. They are colorless under visible light and exhibit strong fluorescence under ultraviolet light excitation.
In recent years, China's UV fluorescent inks have developed rapidly, and colored (visible) UV fluorescent inks and colorless (invisible) UV fluorescent inks have been successfully developed. These fluorescent inks can emit red fluorescence and blue fluorescence under specific ultraviolet light irradiation. , Yellow fluorescence and green fluorescence.
The tax seal on the invoice is printed with colored ultraviolet fluorescent ink. During the day, the tax seal on the invoice is the same as the general unit seal. When the invoice is irradiated with purple light in a dark and dark place, the tax seal appears bright red. The chapter of the unit is black.
2. Thermal anti-counterfeit ink
Thermal anti-counterfeit ink is an ink that can produce a color change effect under the action of temperature. It is usually divided into reversible and irreversible thermal discoloration anti-counterfeiting inks. The discoloration temperature is usually 34 ℃ ～ 100 ℃. According to the different temperature required for discoloration, it can be divided into hand temperature discoloration anti-counterfeiting ink and high temperature discoloration anti-counterfeiting ink. Hand temperature color-changing anti-counterfeiting ink refers to the ink that can produce color-changing effect at the temperature of 34 ℃ ～ 36 ℃; high-temperature color-changing anti-counterfeiting ink refers to the ink that can produce the color changing effect at 40 ℃ ～ 100 ℃ or even higher temperature. To truly meet the requirements for the production of thermal anti-counterfeiting inks, the following conditions must be met: high sensitivity to color change, showing a bright color change in a short time; appropriate color change temperature, the color change temperature should be controlled at 40 ℃ ~ 100 ℃; good stability, Under different climatic conditions, it should be sensitive and effective during the period of use.
â‘ Reversible thermochromic anti-counterfeiting ink. Reversible colors can be produced either by organic compounds or inorganic compounds.
Mechanism of reversible color of organic compounds: The reversible color of organic compounds is due to the change of temperature, the molecular structure changes, that is, the electron donor and electron receiver have moved; two spatial configurations or two The crystal structure changes mutually; the molecules open the ring when heated or generate free radicals, etc., causing the ink color to change.
② Irreversible thermochromic compound. An irreversible color compound refers to a compound whose color cannot be restored when cooled after heating. For example: the dichloride of cobalt chloride pentaamine complex, it changes from pink at room temperature to purple at 120 ℃, sky blue at 170 ℃, black above 230 ℃, when cooled to room temperature, it still remains corresponding to The color of the highest temperature, the ink made with the thermochromic compound as the color material is called the thermal sensitive anti-counterfeiting ink, and it can also be called the thermochromic ink. Thermochromic inks have begun to be widely used in China. Testing temperature with thermochromic inks is quick, accurate, and simple, without any special auxiliary equipment, and the operator can operate without special training.
The thermal sensitive anti-counterfeit ink is easy to detect and suitable for public identification. It is widely used in the packaging of famous brand products, especially cigarette packaging. The disadvantage is the poor color rendering effect of offset printing and embossing, and the good effect of screen printing and gravure printing.
3. Photosensitive anti-counterfeiting ink
Under sunlight, the ink changes from colorless to colored, but after removing the light source, it can be restored to colorless anti-counterfeiting ink. The surface of this ink is discolored due to sunlight, but it is also discolored by ultraviolet light. At present, several domestic solar-induced anti-counterfeiting anti-counterfeiting inks have been successfully developed in China. Their anti-counterfeiting feature is that under the sunlight, the color-changing effect occurs, which can change from colorless to purple, blue, yellow and other colors, and can also be designed to change from colored to colorless .
The advantages of photosensitive color-changing inks are easy identification and good anti-counterfeiting performance, which have been widely used. The disadvantage is poor offset printing and relief printing.
4. Magnetic anti-counterfeiting ink
Magnetic anti-counterfeiting inks are anti-counterfeiting printing inks made with magnetic powder materials (iron oxide and cobalt doped with iron oxide, etc.) as a functional component. It is the most commonly used anti-counterfeiting ink, and its outstanding features are the appearance of deep color, simple detection instrument, and it is mostly used in anti-counterfeiting such as bills and certificates. There are two types of magnetic inks: characteristic and non-characteristic. The so-called characteristic magnetic ink means that the magnetic powder in the ink contains a specific magnetic signal, while the non-characteristic magnetic ink means that the magnetic powder in the ink does not contain a specific magnetic signal, but only magnetic.
In addition to the magnetic ink letter recognition method used by banks and post offices, magnetic ink also has a reader, also known as an optical scanner, which is a device that uses optical principles to recognize letter symbols. Another main use is to print tape strips on credit cards, shopping cards, magnetic cards for meal tickets, IC cards and visit cards. Magnetic ink is used for anti-counterfeiting packaging, which is mainly printed with magnetic ink at a certain position of the packaging and detected by special means to achieve the purpose of anti-counterfeiting. The printing methods are generally flat printing and embossing.
5. Visual discoloration security ink
The anti-counterfeiting ink is a high-tech security anti-counterfeiting ink. It can be printed using traditional engraving gravure. It does not require complex or additional testing equipment to distinguish authenticity. It is suitable for banknotes, trademarks, securities, packaging and printing. Visual discoloration anti-counterfeiting ink has good concealment and is difficult to decipher. It is a security ink developed for the rapid development of color reproduction technology, such as laser scanning color separation machine and color copier.
The principle of visual discoloration anti-counterfeiting ink is: when the viewing angle changes by 60 °, two distinct colors will be produced. The first color is what you see when you are totally reflecting, that is, the color you see at a viewing angle of 90 °. When twisted 60 ° to a viewing angle of 30 °, the first color is cancelled and the second color is enhanced.
6. Pressure sensitive anti-counterfeiting ink
Pressure sensitive anti-counterfeiting ink refers to ink that can appear color under the action of pressure or friction. It is made by adding special chemical reagents or color-changing substances to the ink. Colored or invisible graphics printed with this ink, when rubbed or pressed with a hard object or tool, chemical pressure discoloration or microcapsule rupture dye leaks and colors (red, blue, black, Green, purple, yellow, etc.). According to the user's requirements, select the color of the display and design the dark memory.
7. Anti-tampering and anti-counterfeiting ink
Anti-tampering and anti-counterfeiting inks refer to inks that have a color-developing chemical reaction to chemical substances used for alteration. Print the shading of invoices and all securities with anti-tampering inks. When encountering the correction fluid such as Xiaoziling, these shadings disappear or change color to find traces of alteration.
Anti-counterfeiting ink anti-counterfeiting principle: â‘ Use pigments that can fade when encountering Xiaoziling or other correction fluids, such as some salt-based dyes, to print the shading of the securities amount column. â‘¡ Make anti-tampering inks with binders that can change color when encountering Xiaoziling or some other chemical substances, such as biphenol. The cheque uppercase column printed with this ink, etc., will change color or display the words "obsolete" once it encounters Xiaoziling or other correction fluids.
3. Problems that should be paid attention to in the printing of anti-counterfeiting ink
1. Many anti-counterfeiting inks are colorless inks, that is, they are colorless or white on the printed matter. Therefore, before printing such inks, the ink roller, ink fountain, and ink knife must be cleaned to avoid imprinting on the printed matter. Anti-counterfeiting effect.
2. Many anti-counterfeiting inks have poor alcohol resistance, such as fluorescent and thermal inks. Therefore, when using such inks, it is best not to use alcohol dampening.
3. Restricted by the characteristics of raw materials, many anti-counterfeiting inks are inferior to ordinary inks in offset printing. Therefore, less work is required in printing and product inspection is strengthened to prevent differences in ink color from affecting product quality and anti-counterfeiting effects.
4. Because the direct irradiation of 254nm ultraviolet light will hurt people's skin and eyes, therefore, when using short-wave fluorescence, the product must be tested with a protective device to avoid affecting the health of the product.
25Mm Lashes,3D Mink Eyelashes,Thick Fluffy Mink Lashes,Natural Long Mink Lashes
Zhengzhou Cuka Electronic Commerce Co., Ltd. , https://www.cukalashes.com