The hottest new anti-counterfeiting inks

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Several new anti-counterfeiting inks

release date: Source: China paper

there are a wide variety of inks, including oily, water-based, synthetic resin type, powder, etc. with the development of printing technology, materials science, computer science can not open the refrigerator and a variety of interdisciplinary disciplines, new high-tech inks are also being used more and more, and their uses are mostly some special products, such as banknotes, stamps, various bonds, invoices Promissory note, etc. New inks are mainly used in ticket printing to improve its anti-counterfeiting performance. In addition to expressing the corresponding hue normally, various new inks can also produce special changes under the action of external light, heat, reagents or magnetic fields as a means of identification. This type of ink achieves its anti-counterfeiting performance by changing the formula of the ink or adding some special sensitive materials, such as photosensitive materials, thermal materials, magnetic materials, etc. Because it is difficult to develop this kind of ink and the price of imported products is high, it is difficult to buy in the market, which also increases its anti-counterfeiting in printing. Anti counterfeiting ink is the same as ordinary ink in terms of use. It is suitable for all kinds of printing machines, so it has good versatility. Today, China paper industry takes you into the anti-counterfeiting ink in packaging and printing. Make an introduction to these inks

light variable inks

light variable materials are widely used in the field of printing inks, including sleep based inks, ink based inks, plastic inks, interference inks, etc. according to their different uses. The manufacturing method of this kind of ink is generally to dissolve the photochromic pigment with solvent to make micro pigment capsules, and add adhesives to the dissolved pigment according to different uses. A better manufacturing method is to dissolve the photochromic pigment into coincident monomers, crush the ultrafine particles of this kind of polymer, and make them into powder for use as pigment. Compared with microcapsule ink, the light resistance of the ink made by this method is increased by 10 times. These powders can be used as pigments in water-based inks, oil-based inks, plastic inks and all adhesives

(1) photochromic water-based printing ink

water-based printing ink ranks first in the fiber products industry because of its safe use and convenient operation. Using this water-based ink, printed with 80-120 mesh silk, dried at 100 ℃ for 1min (preferably overnight), and then heated for bridging reaction at 130 ℃ for 3min, you can get products with excellent fiber adhesion. The characteristics of this water-based ink are as follows:

● it can develop color quickly in the sun, and it can return to colorless state in a short time after shading (different colors vary, yellow lasts for 2-3 minutes, and cyan can be completed in an instant)

● dispersion performance, and uniform color printing products can be obtained

● good color rendering and friction firmness

● this water-based ink belongs to liquid ink

● good storage stability and convenient operation

(2) photochromic oil-based ink

oil-based ink is mainly used for surface printing of plastic film, metal plate, etc. This kind of ink is printed with 100-200 mesh silk plate. There are many resins used for adhesives: propylene, epoxy resin, urethane, silicone modified resin, etc. As solvents, there are esters, ketones, etc., and other minerals such as turpentine and petroleum. By adding photochromic materials to these adhesives composed of resins and solvents, the viscosity of printing ink can be properly adjusted to make oil-based printing ink

(3) photochromic plastic ink

according to the survey, there are few printing manufacturers of plastic offset printing ink used in Japan at present. However, in some countries such as the United States, especially in the T-shirt production industry, this printing ink is often used

plastic ink, as a kind of ink that is not easy to dry, often does not need to clean the printing plate, and the ink remaining on the plate can also be used the next day. This kind of plastic ink is made of vinyl acetate copolymer ultrafine powder and DOP plasticizer to expand the particles to make printing ink

photochromatin can also be added to this plastic polymerization agent to make printing ink. However, when the characteristics of the photochromic material itself are suppressed, the photochromic pigment itself is completely decomposed. This phenomenon can only be shown after several days. Therefore, it is difficult to use it as a commodity. However, if the plastic resin does not use vinyl acetate copolymer, but uses an ultra-fine powder material with the same characteristics and can control the denaturation of photochromic pigments, it will be an ideal powder photochromic plastic ink

(4) interference ink

this kind of ink is the most complex of modern anti-counterfeiting inks and is a popular high-tech product at present. Photochromic ink is a kind of reflective ink, which has pearlescent and metal effects. Color copiers and electronic copiers cannot be copied. For products printed with light variable ink, the ink color block presents a pair of colors. Such as magenta blue, green blue, green green, etc. If the pattern is tilted to 60 °, the pattern can be transferred from one color to another. Because only when the ink film on the print is thick, can significant color drift occur, so its printing characteristics cannot be copied by any other ink and printing method

fluorescent ink

fluorescent ink is one of the most widely used inks in ticket printing, and its main component is fluorescent pigment. Fluorescent pigments are functional luminous pigments, which are different from ordinary pigments in that when irradiated by external light (including ultraviolet light), they can absorb a certain form of energy, excite photons, and release the absorbed energy in the form of low visible light, thus producing fluorescent phenomena of different hues. Different colors combine to form unusually bright colors, and when the light stops irradiating, the luminescence phenomenon disappears, so it is called fluorescent pigment. Fluorescent ink can be made by grinding the ratio of fluorescent pigment to polymer resin binder, solvent and additives. This kind of ink, which is invisible to the naked eye, only emits light under ultraviolet or infrared light. It is precisely because of its convertible and hidden characteristics and the characteristics that it cannot be accurately copied on the color copier that the ink is widely used in the special printing industry

fluorescent inks are suitable for printing paper and vinyl films. Because the inorganic fluorescent material is emitted by the crystal, if the pressure is too high, the crystal can be broken, thus reducing the brightness of the luminescence. Therefore, relief printing is generally not used, which is very suitable for plate printing and gravure printing. The rheological properties of most fluorescent inks are plastic like flow and low viscosity, which determines that their printing process is very different from that of ordinary inks. In gravure printing and printing, in addition to paying attention to its viscosity, connecting material, dryness and other characteristics, we should also pay attention to the adjustment of its printing pressure, so as not to make the printing pressure too large and affect the printing effect. When printing, pay attention to the following points:

(1) fluorescent ink is suitable for silk with less than 200 mesh

(3) when the substrate is a transparent object, white ink should be printed first, which can improve the fluorescence effect

thermal ink

thermal ink is a kind of special ink that can change the color of pigments with the change of temperature. Thermal materials can be divided into inorganic, organic, liquid crystal, etc. according to the category, and those used for printing belong to liquid crystal ink. Liquid crystal thermal ink printing is a technology that people are interested in and difficult to master at present. In terms of production method, it also belongs to the type of microcapsule structure ink, but in terms of the characteristics of liquid crystal ink, it mainly uses the characteristics of liquid crystal temperature sensitive discoloration. When making, the liquid crystal and additives enclosed in the micro capsule are dispersed in the connecting material, and its main components are as follows:

● water soluble resin, acrylic copolymer lotion, etc

● micro capsule liquid crystal, cholesterol benzoate, etc

● defoamer, glycerol, etc

this kind of ink does not use pigments. It has good thixotropy, leveling property and viscosity of 4-6pa · s

it is more suitable to adopt the plate printing process, and the following matters need to be paid attention to in the process of use

(1) plate making

generally, nylon or polyester can be used for silk plate. If the printing plate needs a large amount of ink, it can be made of stainless steel. The number of wire mesh is generally 100-175 mesh, which is selected according to the requirements of the diameter of the ink micro capsule and the thickness of the ink layer. The diameter of microcapsules is generally 10-30 μ M. Photosensitive emulsion with strong water resistance should be used in plate making

(2) printing

● the printing plate should be filled with enough ink at one time, and the fixture should be kept clean at any time during the process. It is best not to replenish ink to prevent foaming

● because the microcapsule ink is easy to block the plate, when blocking and foaming are found in the printing, stop the machine immediately to eliminate it and thoroughly wash it with alcohol water

● the printing pressure should not be too high to prevent crushing the liquid crystal capsule

● in order to make the hair color of the printing part obvious, the printing background color should be black or dark tone. The background color can be water-soluble ink or organic solvent ink. Printing methods include printing, offset printing and gravure printing. When using organic solvent ink, it must be fully dried after printing, and the ink film must not remain organic solvent, otherwise it will react with liquid crystal and affect the color development effect

● the printing ink layer should be smooth and bright, and the thickness of the ink layer should be controlled to 20-30 μ m. Uneven or too thin ink layer will reduce the color effect

● the printing sequence can first use black (or dark color) ink to print the background color, and then use liquid crystal ink to print the required pattern; You can also print the base with liquid crystal ink first, and then print the required negative pattern with water-soluble black (or dark color) ink to cover it

(3) drying

● the best drying method is natural drying, which can also be dried with warm wind at about 40 ℃. Do not heat sharply at high temperature

● try not to overlap and stack after drying, and do not add pressure during cutting

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