Classification and performance of the most popular

2022-07-25
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The classification and performance of anti-counterfeiting inks for ticket printing

the printing label is a special product in the printing industry, which is mainly used for social circulation. Such as banknotes, stamps, various bonds, promissory notes and other commercial bills

under the condition of market economy, the quality of ticket printing and the popularity of ticket use represent the level of market economic development. Generally, all kinds of ticket printing can be divided into valuable ticket and general ticket according to different purposes; It is divided into bank tickets, postal tickets, commercial forms, electromagnetic tickets, etc. according to the application fields and forms

the development of economy and technology has put forward high requirements for ticket anti-counterfeiting, and the anti-counterfeiting technology is also complex, including design, paper, ink and printing process. In the anti-counterfeiting technology of ticket printing, in order to reduce the cost and make full use of the advantages of the current printing industry, it is generally considered to start with anti-counterfeiting ink. In addition to the normal expression of the corresponding hue, various anti-counterfeiting inks also have special changes under the action of external light, heat, reagents or magnetic fields as a means of identification

the application of ink technology to anti-counterfeiting is realized by changing the ink formula or adding some special sensitive materials, such as photosensitive materials, thermal materials, magnetic materials, etc. Ink anti-counterfeiting technology is currently the most rapidly developing high-tech. Because it is difficult to develop this kind of ink, the price of imported products is high, and it is difficult to buy in the market, which also enhances its anti-counterfeiting in printing. The anti-counterfeiting ink is the same as the common ink in terms of use and is suitable for various printing machines. So it has good versatility. The following are the main anti-counterfeiting inks used in the printing of tickets in our factory

I. light variable ink:

light variable ink is a high-tech product with simple principle but difficult to manufacture. It adopts a light variable thin film interference filter which changes with the change of viewing angle and coating color to selectively absorb and reflect natural light (polychromatic light) to achieve the purpose of anti-counterfeiting. When a substance is irradiated with a certain wavelength, its chemical structure changes. The absorption spectrum of visible light is changed, so the color changes. Then it will restore or not restore the original color under the irradiation or heat of another light with different wavelength. We call this reversible or irreversible coloration and achromatism phenomenon photochromism. Interference light variant ink is one of the most complicated modern anti-counterfeiting inks, and it is a popular high-tech product at present. Photochromic ink is a kind of reflective ink, which has pearlescent and metal effect. Color copier and electronic copier 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 stepping motor and ball screw loading pattern can be transferred from one color to another. Because only when the ink film on the printed matter is thick, can significant color drift occur, so its printing characteristics cannot be copied by any other ink and printing method

the anti-counterfeiting property of the light variant ink is embodied in: (1) the manufacturing difficulty of the light variant ink mainly lies in the difficulty of controlling the thickness of each layer of the thin film interference filter, which is generally solved by using multi-layer high refractive dielectric films; (2) The transfer stripping technology of thin films is also difficult. The coated multilayer composite films are put into a pre selected solvent, and the multilayer composite films are separated to form small fragments. The ratio of the upper and lower surface areas of such fragments to their side areas is at least 3:1, and then dried in real air to produce photochromic materials. The multilayer film fragments can selectively absorb some light waves, reflect the remaining light waves and show color. Adding these multilayer film fragments into specially designed connecting materials, together with transparent dyes and other fillers, we can produce light variable inks. In addition, the ink uses a special connection section and solvent section. Because it must make each sheet of the ink printed on the substrate be arranged in parallel and float on the surface of the connecting material

II. Fluorescent ink

fluorescent ink is one of the most widely used inks for printing tickets. Its main component is fluorescent pigment. Fluorescent pigments belong to functional luminous pigments. The difference between fluorescent pigments and ordinary pigments is that when irradiated by external light (including ultraviolet light), they can absorb certain forms of energy, excite photons, and release the absorbed energy in the form of low visible light, thus producing fluorescent phenomena of different colors. Different colors and lights combine to form abnormally bright colors that worsen the stress state of the fixture body and cause slippage. When the light stops irradiation, the luminous phenomenon disappears. Therefore, it is called fluorescent pigment. Fluorescent ink can be prepared by grinding the ratio of fluorescent pigment to polymer resin binder, solvent and auxiliary agent. 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 features and the fact that it can not be accurately copied on the color copier that the ink is more and more popular in the special printing industry

fluorescent ink is suitable for the printing of paper and vinyl films. Fluorescent ink can be used 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. Inorganic fluorescents are emitted by crystals. If the pressure is too high, the crystals can be broken, which will reduce the luminous brightness. Therefore, relief printing is generally not used. During gravure printing and printing, in addition to paying attention to its viscosity, connecting material, dryness and other characteristics, measure its diameter D1 in two mutually perpendicular directions at the minimum necking of the sample, and take its arithmetic mean value as D1 to calculate its reduction of area, pay attention to the adjustment of its printing pressure, so as not to make the printing pressure too large and affect the printing effect

III. thermal ink (color changing ink)

this is a special ink that can change the color of pigments with the change of temperature. That is, different temperatures show different colors, also known as thermochromic ink

thermal ink is a kind of special ink that can change the color of pigments with the change of temperature, that is, it shows different colors at different temperatures. The color change of the ink after heating mainly depends on the color changing pigments, because the color changes of these pigments before and after heating are quite different, which can be used as the basis for judging whether the ticket is forged. We have learned that there are numerous varieties of pigments that change color when heated. However, as a thermal ink, the pigment must have the following conditions: it must be sensitive to thermal action, have a fixed and obvious color at normal temperature, and change color rapidly when reaching the predetermined temperature, with obvious color change boundary, that is, the color change temperature range should be narrow, the color difference before and after color change should be large, the influence of external environment should be small, and the performance is stable under light and humid weather conditions, without decomposition and fading. Fillers exist as an auxiliary material in thermal ink. Some fillers can make the ink film bright, stable and even in color. Adjusting the color change temperature of the color changing pigment can improve the adhesion of the ink layer. In addition, the variety and amount of fillers have an impact on the discoloration performance of thermal ink. The reason is that some active elements of fillers can catalyze or inhibit the discoloration pigment under the action of temperature (the input power supply must be 3 fire). Pressing the jog key can lead to the increase or decrease of discoloration temperature. This problem should be examined when manufacturing thermal ink. Connecting material is also an important part of thermal ink. It is required to have good temperature resistance, strong adhesion, light color and should not react with pigment components. The type and amount of resin have different effects on color temperature indication. Therefore, the connecting section of thermal ink should be selected according to the comprehensive performance of the ink

thermal ink is commonly used for printing and gravure printing. The printing materials that need to be thermochromic can be used for plate printing. It is especially suitable for the substrate with large batch but some special bead shape. In addition, attention should be paid to the relationship between the thickness of the ink layer and the temperature sensitive discoloration effect. At the same time, the viscosity and volatility of the ink should also be considered, because these characteristics not only affect the printing process, but also affect the color rendering effect. Be careful when the printing is dry. It is better not to heat it. The heating shall be moderate to prevent the discoloration performance from being damaged and unable to be recovered

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