Types of security printing inks
Anti-counterfeiting printing ink is an important part of anti-counterfeiting technology. Anti-counterfeiting ink is an ink with anti-counterfeiting function. The ink is composed of color material, linking material and ink additives, that is, adding special performance anti-counterfeiting materials to the ink connecting material. Special printing ink processed by special process. Its anti-counterfeiting ability is based on the use of colorants and linking materials that have special functions in ink to prevent falsification. Today, in many fields of security printing, the use of anti-counterfeiting printing inks is very widespread. For example, anti-counterfeiting printing inks are used in various security printings such as documents, documents, trademarks, and signs. This is mainly due to the fact that anti-counterfeiting printing inks have the features of easy implementation of anti-counterfeiting technology, low cost, better concealment, and vivid colors. At present, there are dozens of inks used for security printing developed at home and abroad, which can be divided into letterpress printing inks, gravure printing inks, stencil printing inks, lithographic printing (offset printing) inks, and waterborne flexo printing inks. Different things can be divided into paper ink, printing ink, news ink, plastic ink and so on.
In addition, security ink can be divided into seven major categories according to its anti-counterfeiting function.
The first type, ultraviolet excitation fluorescent ink;
The second type, sunlight-induced color change inks;
The third category, thermal security ink (thermochromic ink);
The fourth category, chemical reaction color ink;
The fifth category, intelligent machine reading (machine expert identification) security ink;
Sixth, multi-functional or integrated security ink (laser hologram plus fluorescent security ink);
The seventh category, other special inks, such as OVI light variable security ink.
The specific implementation is mainly realized in the form of ink printing on tickets, product trademarks and packaging. These anti-counterfeiting technologies are characterized by the implementation of different external conditions, the main use of light, heat, spectral detection and other forms, to observe the color change of ink samples to achieve anti-counterfeiting purposes. Its implementation process is simple, low cost, good concealment, colorful, and easy inspection. However, smart machine reading (machine expert identification) anti-counterfeiting ink is the first choice for anti-counterfeiting technology for banknotes, tickets, tickets, and trademark packaging because of its complex detection, strong reproducibility, and diverse color changes. From the point of view of reaction characteristics and verification methods, security inks can be broadly divided into fluorescent inks, ultraviolet inks, thermal (warm) variable inks, temperature-sensitive color-changing inks, reaction color-changing inks, friction-chromic inks, and infrared anti-counterfeiting inks. Modified inks, invisible inks, magnetic inks, chemically-encrypted anti-counterfeiting inks, etc. are currently common as follows:
A. Thermochromic ink:
The principle of anti-counterfeiting is that the color material uses a substance whose color changes with temperature. Anti-counterfeiting features are changes in the color of the hand or when heated. This ink is now available in colors that are reversible, irreversible, and memory. For example, a pink chloride drill, hexamethylenetetramine (CoC12?2C6H12N4?10H20), loses crystal water (CoC12?2C6H12N4) when it rises to 35 degrees Celsius and turns sky blue when the temperature drops It absorbs moisture from the air and returns to its original color. Another example is the red cube of mercury iodide (HgI2), when heated to 137 degrees Celsius turns into blue orthorhombic crystals, cooled to room temperature, then returned to the original cyan square crystal.
Second, photosensitive color ink:
A photochromic or photoactive compound is added to the ink. Anti-counterfeiting feature is that the ink can change from colorless to colored, or from orange to black under sunlight. This ink looks like it is discolored under the sun, and it is essentially a change in ultraviolet radiation, with a wavelength of 400 to 800 nm.
Three. Humidity-sensitive color ink:
The principle of anti-counterfeiting is that the color material contains substances that change with humidity. The anti-counterfeiting feature is that the dry state is colorless, and the wet state becomes colored. This ink is reversible and irreversible, with blue, green, red and black colors.
Four. Pressure sensitive color ink:
The principle of anti-counterfeiting is to add special chemical reagents or pressure-sensitive, color-changing compounds or microcapsules to the ink. Its security features are colored or invisible graphics printed with this type of ink. When the hard object or tool is rubbed or pressed, chemical pressure change or discoloration of the dye of the micro-limb capsule breaks. The existing color and colorless points, pressure-induced color red, green, blue, purple, yellow and other colors, according to the user's request to select the display color and design notes. V. UV fluorescent ink:
The anti-counterfeiting principle is the addition of a visible fluorescing compound with ultraviolet excitation in the ink. The anti-counterfeiting feature emits red, yellow, green, and blue (400 to 800 nm) visible light under ultraviolet light (200 to 400 nm). This ink has a color and colorless distinction, there are two kinds of long wave (365nm) and short wave (254nm).
6. Infrared fluorescent ink:
The anti-counterfeit principle is to add visible fluorescent compounds with infrared excitation to the ink. Security features emit green visible light under infrared lamps. Different infrared fluorescent substances have different requirements on the infrared spectrum power.
7. Sunlight-induced color change inks:
The principle of anti-counterfeiting is to add a colorless, isomeric, organic photosensitive material molecule to the ink, which contains two localized pi-bond systems that absorb only ultraviolet light in sunlight. The anti-counterfeit feature is that when -CY=0 in the photosensitive material molecule is decomposed by the ultraviolet light in the wavelength band of 300-360 nm, these two localized π-bond systems can become a delocalized π-bond system, and this delocalized domain The π bond system absorbs some visible light and produces a certain color. It is a newly-developed daylight-inspired color-changing anti-counterfeiting ink that can detect authenticity as long as sunlight is used. Eight infrared absorption ink:
Anti-counterfeit principle is to add infrared absorption material in the ink. Anti-counterfeiting features are under the infrared detector to identify invisible marks or graphics under normal light. Due to the different intensity of infrared absorption by the substance, it is required that the infrared detector should have a certain sensitivity to accurately detect its authenticity.
9. Perspective color ink:
The principle of anti-counterfeiting is that the colorant uses multilayer interference optical debris. Anti-counterfeiting features change the color of the print when it is viewed. The technical requirement is to control the film thickness. In addition, there are many groups of colors such as green-black, red-green, and gold-gray.
X. magnetic security ink:
Anti-counterfeit principle is that the color material uses magnetic substances, such as iron oxide or iron oxide to add cobalt and other chemical substances. Anti-counterfeiting feature is the use of magnetic detector can detect the magnetic signal and decode. The technical requirement is that the magnetic colorant is needle-shaped crystals smaller than micrometers, so that its size and shape can be easily and uniformly arranged in the magnetic field. This magnetic property is produced by the magnetic pigment contained in the ink. The best magnetic pigments are Fe3O4 and Fe2O3. Most of these pigments are needle-shaped crystals smaller than micrometers, and the size and shape of these particles make them extremely easy to align in a magnetic field, resulting in a relatively high residual magnetism. The symbols and numerals with this residual magnetism realize the discrimination function by the friction in the automatic processing device. It is the most commonly used anti-counterfeit ink, its outstanding feature is the appearance of deep color, simple detection equipment.
Eleven. Anti-printing ink:
The principle of anti-counterfeiting is to add chemical substances for altering or substances with a color-developing chemical reaction to the ink. The anti-counterfeiting feature is that when the correction fluid such as the eraser is encountered, the anti-printing shading will appear discolored or discolored. When encountering correction fluid such as erasing spirit, the printed matter has the differences of fading, coloration and discoloration.
X. Chemical Encryption Ink:
The anti-counterfeiting principle is the addition of specific compounds to the ink. Its anti-counterfeiting feature applies a demystifying chemical test within a predetermined range and immediately reveals concealed images or produces fluorescence. Different temperatures and pressures have different combinations of encoding and decoding.
XIII. Stealth security ink:
The anti-counterfeit principle is to add invisible marks such as Isotag, Coircode, etc. to the general ink. Its anti-counterfeiting feature is due to the fact that these marks are invisible, and only when professionals and certain instruments and light of a specific wavelength irradiate the specific marks appear, and thus the authenticity thereof can be identified. Its technical content is higher and its anti-counterfeiting performance is better.
XIV. Intelligent Machine Read Security Ink:
The principle of anti-counterfeiting is to use the variability of intelligent anti-counterfeit materials, that is, the anti-counterfeiting material consists of a variety of variable chemical substances, including the nature, type, quantity, content, and existing forms of the characteristic compounds to constitute the particularity and individuality of the security materials. Then, according to these special characteristics and the production of anti-counterfeiting materials and manufactured detection equipment (can be processed by the calculator, the results obtained, the authenticity of the test) to achieve anti-counterfeiting purposes. Its security features include: (1) Uniqueness and complexity. The technology used in the technology has many components, many production equipments, large investment, and complicated processing technology. (2) High technology content. The technology spans multiple disciplines and integrates multidisciplinary science and technology. (3) Intuitive and quick. The results can be seen directly from the calculator screen in 5 to 30 seconds. (4) Dedicated. Due to the use of calculator identification, the variability is extremely strong. Each authentication terminal has anti-counterfeit products and machine encryption. Only when it knows the identity of the seized mark or the seal code at the same time can it be identified with a dedicated detection instrument.
15. Multifunctional or integrated security inks:
Anti-counterfeit principle is to add other anti-counterfeiting technology in the general anti-counterfeit ink, so as to achieve multiple anti-counterfeiting functions. For example, a laser holographic logo combined with a fluorescent encryption security ink. Its anti-counterfeiting features, such as laser hologram identification combined with fluorescence encryption anti-counterfeiting ink, add new anti-counterfeiting measures to perform secondary encryption without increasing the integrity of the laser holographic identity, thereby improving its anti-counterfeiting function. Currently, a secondary encryption comprehensive anti-counterfeiting technology for laser hologram identification has been adopted on the market, ie, a special fluorescent material that can be detected through a certain process after being added to the laser hologram logo, is invisible to the naked eye under sunlight, and displays special features in the detection of special instruments. Colored fluorescent graphic. The technology has the characteristics of friction resistance, heat resistance, convenient and accurate detection, and strong anti-counterfeiting, and the production cost is less increased. 16. Light Variable Ink (OVI):
The principle of anti-counterfeiting is to add special materials to the ink, which will cause discoloration of the seal under different lighting angles. This is a kind of anti-counterfeiting ink with high technological content. Due to the complicated raw material production process, high technical difficulty, and large investment in equipment, the cost is relatively high and it is very difficult to prevent it. This kind of ink is mainly used for the printing of important documents such as banknotes, evidence, identity cards, passports, and securities. The inks that can only be adapted to the printing are gravure printing and screen printing. However, at present, there is also a dioptric ink which also has a refractive color effect. Due to its simple processing of raw materials, although the color change effect is far less than OVI, it can also play a security effect, and the cost is relatively low.
Seventeen nano ink:
Nanomaterials and nanotechnology are emerging high-tech products. Now they have developed rapidly. They have begun to penetrate into various fields and have successfully obtained a lot of high-performance and special-performance materials. This is a new material in the history of material development. Milestones. Nanometers are a unit of length, meaning that the material itself is in an ultra-small, ultra-fine state. Based on the various properties of nanomaterials, applying it to the ink system will bring a huge boost to the ink industry. Actually, there are many ways to obtain nanomaterials, such as high-temperature sintering (such as sintering of carbon nanotubes), precipitation, high-temperature water dissolution, chemical vapor condensation, or modern plasma energy polymerization. By means of the above methods, various components in the ink, such as resins, pigments, fillers, etc., can be made into nanoscale raw materials. In this way, because of their high degree of fineness, they have good flow and lubricity, they can achieve better dispersion, suspension, and stability. The amount of pigment used is less, but the hiding power is high, the gloss is good, the resin particle size is fine, and the film formation is continuous, uniform and smooth. The layer is thin, but the image is clear. If used in a UV ink, it may result in a faster curing rate while eliminating shrinkage wrinkling of the film due to the fine and uniform dispersion of the filler. In the glass-ceramic ink, if the inorganic material constitutes nano-scale fineness, it will save a lot of raw materials and print