Using ink made of magnetizable materials, the characters can be printed on some kind of substrate, such as new bank checks, credit cards, etc., which can be read by electronic reading equipment.
Chinese name: magnetic ink mbth: magic printing ink printing method: printing technology Ink raw materials: introduction of magnetizable pigment, composition of magnetic ink, characteristics of magnetic ink, research progress, application, printing method and technical category. Introduction to the composition of magnetic ink The basic composition of magnetic ink is the same as that of ordinary ink, that is, it is composed of pigments, binders, fillers and additives, but the pigments used in magnetic ink are not pigments, but ferromagnetic materials. Pigment of magnetic ink Magnetic ink is magnetic because the magnetic pigment in the ink can remain magnetic after magnetization. As one of the most important components of magnetic ink, it determines the final printing effect of ink. The main components of magnetic ink are magnetic pigments, and the best magnetic pigments are iron oxide black (Fe 3 O 4) and iron oxide brown (Fe 2 O 3). Most of these pigments are needle-like crystals smaller than 1μm, and their particle size and shape make them easy to be evenly arranged in the magnetic field, thus obtaining relatively high remanence. The fluidity, adhesion, dryness and printability of magnetic ink are mainly determined by the binder. Binder is the fluid component of ink, and the binder of magnetic ink is also the basis of ink quality. The binding material of magnetic ink is similar to ordinary ink. Vegetable oil, animal oil and mineral oil can be selected, but synthetic resin is more used as its binding material. Representative synthetic resins include alkyd resin, polyurethane vinegar, epoxy resin, acrylamide, polyvinyl acetate, vinyl chloride-acetic acid copolymer, polyvinyl butyral, polyvinylether, nitrocellulose and polyurethane vinegar resin. Generally, long oil (65%) alkyd resin is used as paste ink. This resin has good color retention, good luster and excellent anvil adhesion in iron ink. In addition, because of its good solubility, it is also widely used in screen printing ink. Filler of magnetic ink In magnetic ink, the function of filler is mainly to adjust the properties of ink, such as dilution and fluidity. In addition, the amount of pigment can be reduced, which can reduce the cost of ink. According to the different characteristics and requirements of products, environmental protection filler can be an additional part of pigment or adhesive, and can also be used as an additional part of finished ink. Additives for magnetic ink There are many kinds of additives in magnetic ink, which can be divided into stabilizers, desiccants, plasticizers, coupling agents, lubricants and solvents according to their different functions. The function of stabilizer is to prevent the aging and deterioration of connecting materials. Commonly used are metal organic acid salts, such as barium stearate. The role of coupling agent is to make the magnetic pigment better dispersed in the binder, and at the same time increase the bonding strength. Commonly used coupling agents are silane and ferrite. It is pointed out that bonded magnets with silane coupling agent can obtain higher mechanical properties, while bonded magnets with citric acid-vinegar coupling agent can obtain higher magnetic properties. When the amount of ferrite vinegar coupling agent is 1% (mass fraction) and xylene is used as solvent, the magnet can obtain good comprehensive properties. Lubricant has many functions: it can not only improve the dispersibility of magnetic powder, the plasticity of magnetic layer and prevent brittleness caused by aging, but also play a lubricating role around the adhesive, thus overcoming the agglomeration of magnetic powder. Solvent can dissolve the used adhesive and make the magnetic paddle have advection. When choosing, we should pay attention to the appropriate boiling point, and the boiling point should not be too low, which will cause the evaporation loss to be too fast and make it difficult to keep the viscosity of magnetic slurry constant. The boiling point should not be too high, otherwise the magnetosphere will be difficult to dry. Commonly used solvents for magnetic ink are: methyl ethyl ketone, acetone, cyclic ethyl ketone, toluene, xylene, diacetone alcohol, isopropanol, butanol, etc. The rheological properties of magnetic ink are basically similar to those of ordinary ink, but the ink properties are a little short and its fluidity is relatively poor. The conjunctival fastness of printed matter is based on the friction in the automatic processing device. Magnetic ink is magnetic because the pigment used in the ink formula has the ability to retain magnetism after being treated by magnetic field. Of course, the ink itself is not magnetic before magnetization. There are many factors that affect magnetism, such as the magnetism of pigment, the content of magnetic pigment in ink, the thickness of ink film after printing and so on. Characteristics of magnetic ink The disadvantages of these pigments are relatively large oil absorption and unsatisfactory transfer performance. Therefore, some granular or cubic iron oxides are sometimes used to improve their printing performance. Because the remanence of these iron oxides is poor, the dosage should not be too much. Another advantage of it is that it can be used as a pigment in the formula (because of its small oil absorption), thus improving the transfer characteristics of ink. Binder is a fluid component of ink, and the fluidity, viscosity, dryness and printability of ink mainly depend on binder. The connecting material of magnetic ink is also the basis of ink quality. The binder of magnetic ink is similar to ordinary ink, and vegetable oil, animal oil and mineral oil can be selected, but synthetic resin is more used as the binder of magnetic ink. The filler in magnetic ink can also reduce the amount and cost of pigment, adjust the properties of ink, such as density and fluidity, and improve the flexibility of formula design. In addition, the additive in magnetic ink can be an additional part of pigment, adhesive or finished ink, mainly depending on the characteristics and requirements of the product. For different printing methods, magnetic ink may be different, but no matter what printing method, the characteristics of magnetic pigments in magnetic ink are basically the same, and the difference is mainly the binder, which may be the proportion of ingredients in the ink formula. Research Progress Magnetic ink has been used for more than 40 years, and dozens of anti-counterfeiting magnetic inks have been developed at home and abroad. The main advantages of these inks are convenient implementation of anti-counterfeiting technology, good concealment and low cost. However, as a kind of anti-counterfeiting ink, its outstanding feature is its strong technical blockade, which makes it difficult to develop high-quality magnetic ink successfully. At present, many domestic manufacturers produce magnetic ink, but they can't compete with foreign products in quality. Users who need high-performance and high-quality magnetic ink still need to import a large number from the United States and Japan. In the research of anti-counterfeiting magnetic ink, a very urgent problem is how to break the foreign technical monopoly and develop high-performance and high-quality products. Magic lnk Printing, as a printing technology of special ink, refers to the method of printing with magnetic ink mixed with iron oxide powder. Magnetic ink printing belongs to the technical field of magnetic recording. The magnetic recording body is made by magnetic printing, which makes it have the required special properties. Magnetic printing has applications in many fields, such as tickets, monthly tickets, printing, bank passbooks, ID cards and so on. The price description card is made of magnetic film; Data registration forms and checks can also be printed with magnetic ink and other items. In a word, magnetic printing is widely used.