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2022-10-24

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Analysis of the current situation of anti-counterfeiting printing ink (Part 1)

ink is the main material of printing. When it comes to printing, it should always be mentioned that ink. Generally, ink for printing is a very common material. However, in recent years, with the development and growth of anti-counterfeiting printing, special ink for special printing is gradually understood and familiar by the world

types of anti-counterfeiting printing inks

anti counterfeiting printing inks are an important part of anti-counterfeiting technology. Anti counterfeiting inks refer to inks with anti-counterfeiting functions. The inks are composed of pigments, binders and ink additives, that is, special printing inks made by adding anti-counterfeiting materials with special properties into ink binders and processing by special processes. The reason why it can prevent counterfeiting is that it uses pigments and binders with special functions in ink to prevent counterfeiting. Nowadays, in many areas of anti-counterfeiting printing, anti-counterfeiting printing ink is widely used, such as in the anti-counterfeiting printing of various tickets, documents, trademarks and logos. This is mainly because the anti-counterfeiting printing ink has the characteristics of convenient implementation of anti-counterfeiting technology, low cost, good concealment, bright colors and so on. At present, there are dozens of inks used in anti-counterfeiting printing developed at home and abroad. According to the printing form, they can be divided into relief printing ink, gravure printing ink, hole printing ink, lithography (offset) ink and water-based flexographic printing ink, etc. according to the different substrates, they can also be divided into paper ink, iron printing ink, ink, plastic ink, etc

in addition, anti-counterfeiting inks can be divided into seven categories according to their anti-counterfeiting functions

the first type, UV excited fluorescent ink

the second category is photochromic ink excited by sunlight

the third category is thermal anti-counterfeiting ink (thermochromic ink)

the fourth category, chemical reaction color changing ink

the fifth category, intelligent machine readable (machine expert identification) anti-counterfeiting ink

category VI, multifunctional or comprehensive anti-counterfeiting ink (laser holography plus fluorescent anti-counterfeiting ink)

the seventh category is other special inks, such as Ovi light variable anti-counterfeiting inks

the specific implementation is mainly achieved by ink printing on tickets, product trademarks and packaging. These anti-counterfeiting technologies are characterized by the implementation of different external conditions, mainly in the form of light, heat, spectrum detection, etc., to observe the color changes of ink samples to achieve the purpose of anti-counterfeiting. Its implementation process is simple, low cost, good concealment, bright colors and convenient inspection. However, intelligent machine-readable (machine expert identification) anti-counterfeiting ink is the preferred anti-counterfeiting technology for paper money, ticket cards, tickets and trademark packaging in various countries due to its complex detection, strong reproducibility and diverse color changes. In terms of reaction characteristics and verification methods, anti-counterfeiting inks can be generally divided into fluorescent inks, ultraviolet inks, thermal (temperature) variable inks, temperature sensitive variable inks, reactive variable inks, friction variable inks, infrared anti-counterfeiting inks, anti erasure inks, invisible inks, magnetic inks, chemical encryption anti-counterfeiting inks, etc. at present, the common ones are as follows:

I Thermosensitive color changing ink:

the anti-counterfeiting principle is that the color material adopts substances whose color changes with temperature. The anti-counterfeiting feature is that the color changes when it feels or is heated. This ink now has three kinds: color reversible, color irreversible and memory. For example: Pink chlorinated diamond? Hexamethylene tetramine (coc12? 2c6h12n4? 10h20) loses crystal water (coc12? 2c6h12n4) and turns sky blue when the temperature rises to 35 ℃. When the temperature drops, it absorbs water in the air and returns to the primary color. Another example is the red cube of mercury iodide (HgI2), which turns into a cyan orthorhombic crystal when heated to 137 degrees Celsius. After cooling to room temperature, it returns to the original cyan orthorhombic crystal

II Photochromic ink:

Add photochromic or light activated compounds to the ink. The anti-counterfeiting feature is that the ink can change from colorless to colored, or from orange to black in the sun. This ink looks like changing color in the sun, which is essentially changed by ultraviolet radiation, with a wavelength of 400 ~ 800nm

III Humidity sensitive color changing ink:

the anti-counterfeiting principle is that the pigment contains substances whose color changes with humidity. The anti-counterfeiting feature is that the dry state becomes colorless and the wet state becomes colored. This ink can be reversible or irreversible, with four colors of blue, green, red and black

IV Pressure sensitive color changing ink:

the anti-counterfeiting principle is to add special chemistry to the ink. It is expected that the pig iron market will be dominated by weak wait-and-see reagents or pressure-sensitive compounds or microcapsules that cause color change in a short time. Its anti-counterfeiting feature is that the colored or invisible pictures and texts printed with this ink will undergo chemical pressure color change or color change of microcapsule rupture dye when hard objects or tools are rubbed and pressed. At present, there are colored and colorless colors. The pressure induced color includes red, green, blue, purple, yellow and other colors. You can choose the displayed color and design a secret mark according to the requirements of users

5 UV fluorescent ink:

the anti-counterfeiting principle is to add visible fluorescent (complex) compounds with UV excitation to the ink. The anti-counterfeiting feature is that it emits visible light of red, yellow, green and blue (400~800nm) under ultraviolet light (200 ~ 400nm). This ink can be colored or colorless, including long wave (365nm) and short wave (254nm)

VI Infrared fluorescent ink:

the anti-counterfeiting principle is to add visible fluorescent compounds with infrared excitation to the ink. The anti-counterfeiting feature is that it emits green visible light under the infrared light. Different infrared fluorescent substances have different requirements for infrared spectral power. Insert the test piece vertically between the cylinder and the pressure roller shaft (the coating faces the zigzag column)

VII Sunlight excited color changing ink:

the anti-counterfeiting principle is to add colorless isomer organic photosensitive material molecules into the ink, which contains two localized π bond systems that only absorb ultraviolet light in sunlight. The anti-counterfeiting feature is that when the - cy=0 in the photosensitive material molecule is decomposed by the measurement of the excitation force of ultraviolet light in the 300 ~ 360nm band, the two localized π bond systems can become an delocalized π bond system, and the delocalized π bond system can absorb some visible light and produce some color. It is a newly developed sunlight induced color changing anti-counterfeiting ink, which can detect the authenticity as long as the sunlight is used

VIII Infrared absorbing ink:

the anti-counterfeiting principle is to add infrared absorbing substances to the ink. The anti-counterfeiting feature is that under the infrared detector, invisible marks or graphics can be recognized under ordinary light. Because substances absorb infrared rays with different intensities, infrared detectors are required to have a certain sensitivity to accurately detect their authenticity

IX Perspective color changing ink:

the anti-counterfeiting principle is that the pigment adopts multi-layer interference optical film. The anti-counterfeiting feature is that the color will change when the viewing angle of the printed matter is changed. The technical requirement is to control the thickness of the film. In addition, there are many groups of color changes, such as green black, red green, gold gray, etc

ten Magnetic anti-counterfeiting ink:

the anti-counterfeiting principle is that the pigment uses magnetic substances, such as iron oxide or cobalt and other chemical substances added to iron oxide. The anti-counterfeiting feature is that the magnetic signal can be detected and decoded by the magnetic detector. The technical requirement is that the magnetic pigment is needle like crystal less than micron level, so that its size and shape can be easily and evenly arranged in the magnetic field. This magnetism is produced by the magnetic pigments contained in the ink. The best magnetic pigments are ferric oxide (Fe304) and iron oxide (Fe20). Most of these pigments are needle shaped crystals smaller than microns. Such particle size and shape make it easy for them to be evenly arranged in the magnetic field, so as to obtain relatively high residual magnetism. The symbols and numbers with this residual magnetism realize the recognition function through the friction in the automatic processing device. It is the most commonly used anti-counterfeiting ink, which is characterized by deep appearance color and simple detection instrument

Xi Anti erasure ink:

the anti-counterfeiting principle is to add chemicals used for coating or substances with color reaction to the ink. The anti-counterfeiting feature is that the anti erasure shading will fade or change color when encountering erasure liquid such as xiaoziling. When encountering erasure liquid such as xiaoziling, the printed matter has the differences of fading, color rendering and discoloration