Application of heat sensitive anti-counterfeiting

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Application of heat sensitive anti-counterfeiting in cigarette label printing

cigarette label printing is a representative of process innovation in the printing industry Innovation in the field of anti - counterfeiting printing covers a wide range of fields In order to prevent the counterfeiting of cigarettes, the anti-counterfeiting printing technology of cigarette labels can enable ordinary consumers to quickly identify the authenticity of cigarettes with the simplest method in the shortest time. Code anti-counterfeiting technology, paper anti-counterfeiting technology and super line multi-color overprint are effective means of cigarette label anti-counterfeiting printing. At the same time, the printing of special inks such as UV fluorescent ink, sunlight color changing ink, thermal anti-counterfeiting ink (temperature variable ink) has become the key to the anti-counterfeiting of cigarette label printing In particular, thermal anti-counterfeiting ink has strong competitive advantages in terms of rich color, close to the effect of ordinary printing process, relatively low printing cost and easy identification, and is more widely used in anti-counterfeiting printing of cigarette labels

principle of thermal anti-counterfeiting printing

thermal anti-counterfeiting printing is to use thermal anti-counterfeiting ink It is printed in a special position that is easy to identify or printed into special words or patterns. The change of the printed words or patterns is observed by raising the temperature to identify the authenticity of the product. The heat sensitive anti-counterfeiting detection is convenient, rapid, accurate and simple. It does not shake any special auxiliary instruments, and the operators can actually operate without special training. It is suitable for ordinary consumers It is widely used in the field of cigarette label printing

1. Classification of heat sensitive anti-counterfeiting inks Ink that shows different color effects. Simply speaking, it is an ink that can change color according to temperature. Here, the color change temperature is 34-1000c. Generally, according to the temperature required for color change, it can be divided into hand temperature color change anti-counterfeiting ink and high-temperature color change anti-counterfeiting ink; according to the effect of color change, it can be divided into reversible and irreversible color change anti-counterfeiting ink; according to the difference of color change mode, it can be divided into single color change reversible Multi color reversible single color irreversible and multi color irreversible heat sensitive anti-counterfeiting ink

hand temperature color changing anti-counterfeiting ink refers to the temperature range of 34-360c Ink capable of color change reaction of printed words or patterns: high temperature color change anti-counterfeiting ink is at 34c-100c Even at higher temperatures, printing words or patterns can change color

the finished printed product displays a certain color at room temperature After heating, the color of printed words or patterns disappears and becomes colorless Or change to another specific color after increasing the temperature, and immediately return to the original color after cooling Because its change process is reversible And it can be repeated many times, so it is called reversible color changing ink; After the temperature is raised, it changes from colorless or from a specific color to another specific color, and the displayed color will not disappear or recover after the temperature is restored, so it is called irreversible color changing ink

according to the color change difference in the process of high temperature color change, it can be divided into single color change reversible, multi color change reversible, single color change irreversible and multi color change irreversible thermal anti-counterfeiting inks. Irreversible color change modes mainly include (at 70-90c): from colorless to red, colorless to black, etc. Reversible color change modes are: Red becomes colorless, black becomes colorless, blue becomes colorless, etc Of course, according to the design requirements of cigarette labels It can also be designed to be colored into other colors

2. Working principle of thermal ink

thermal anti-counterfeiting ink mainly relies on dry thermal discoloration substances. Thermochromic substances can be divided into organic compounds and inorganic compounds, and can also be subdivided into inorganic salts' coordination compounds, organic compounds (dye molecules) and liquid crystal polymers

① reversible discoloration mechanism: with the change of temperature, the thermosensitive extruder can be divided into single screw extruder, twin screw extruder and multi screw extruder according to the number of screws. The molecular structure of color substance changes, that is, the electron donor and electron receiver move; Two spatial configurations or two crystal structures change each other: the ring opening of molecules by heating or the generation of free radicals cause the color change of ink. Its color change can be divided into sublimation, melting, thermal decomposition, oxidation and curing reactions, mainly due to the loss of crystal water Crystal transformation or discoloration due to pH change. Therefore, when the heat source is eliminated, the color of the ink can be restored to the original state. For example, the pink halogenated diamond hexamethylene tetramine loses crystal water when the temperature rises to 35 ℃ and turns into sky blue. When the temperature drops, it absorbs the water in the air and returns to the primary color. Another example is the red cube of mercuric iodide (hg:h912) which becomes a cyan orthorhombic crystal when heated to 137 ℃ After cooling to room temperature, it returns to the original cyan square crystal

② irreversible discoloration mechanism: when the heat sensitive discoloration material is heated, physical or chemical changes occur, which changes the original physical and chemical properties, resulting in color changes. Therefore, when the heat source is removed, the ink color cannot return to the original color. For example, the diazonium compound of the pentamine complex of nitriding diamond changes from pink at room temperature to purple at 120c and sky blue at 170C Black above 230C, when cooled to room temperature, still retains the color corresponding to the maximum temperature

3. Thermochromic substances

thermochromic substances that really meet the requirements for the actual production of thermochromic anti-counterfeiting inks must meet the following three conditions:

① high thermochromic sensitivity: the color printed in a short time during the detection process can change significantly, and the color contrast before and after color change should be high

② the color change temperature range is appropriate: the color change temperature should be within the range of 40-100`c, which is mainly to facilitate the detection of anti-counterfeiting ink

③ good discoloration stability: under different environmental conditions such as temperature, humidity and light intensity, the ink can achieve good discoloration effect and has quite high sensitivity within the validity period of the ink

application of heat sensitive anti-counterfeiting in cigarette labels

sensitive anti-counterfeiting is widely used in cigarette labels because it is simple and easy to identify, especially it can quickly identify the authenticity of products by heating without damaging the outer packaging

1. Used for special words and patterns

to highlight the name, logo or icon of the product This is also the focus of consumers Using heat sensitive anti-counterfeiting in these areas is also the most effective way to reduce dependence on foreign key technologies Printing thermal anti-counterfeiting ink can not only enhance the color effect of these words or patterns, but also enhance consumers' impression of these proprietary words or patterns through the anti-counterfeiting identification process. In view of the printing effect and high price in the thermal anti-counterfeiting oil, it is rarely used in the main text or main pattern of the product. Usually, it is used in the English, Chinese pinyin or part of the theme pattern of the cigarette label brand, which can not only achieve the effect of identifying the product It can also reduce the cost of cigarette label printing. The products adopting this method include "New Century Golden Leaf", "red hard scattered flower", "special drunk scattered flower" and other products

2. Used in specific areas

this is mainly for the same type of products We should use heat sensitive anti-counterfeiting technology in a specific area, a bundle of onions and a bag Through the use of heat sensitive anti-counterfeiting oil, consumers will actively and consciously identify the authenticity of products when purchasing similar products. In general, the specific areas at the flip part, bottom or upper part of the cigarette label are not important parts of the cigarette label. The use of thermal anti-counterfeiting can embellish the whole pattern, facilitate heating operation, and facilitate the unification with the same type of products. The "red hard golden Xuchang" and "Huahong hard red flag canal" have adopted this method "And other products.

3. pay attention to the coordination with the overall pattern in the design.

due to the large particle size of the thermal anti-counterfeiting ink and the insufficient color depth of the ink, the thermal anti-counterfeiting printing effect is rough and the color is light. In the design, we should pay attention to the coordination with the overall and local patterns and colors. In the end, we can not only make it easy for consumers to identify, but also promote the improvement of the grade of the whole cigarette label.

problems existing in the thermal anti-counterfeiting

1 Thermal anti-counterfeiting inks have large particle size and light color depth.

the thermal anti-counterfeiting inks in the current market still have the problems of large particle size and light color depth, which not only causes rough printing effect, but also is not conducive to the coordination with other color patterns. Generally, the effect of silk printing is very ideal The problems of ink layer thickness and color depth have also been solved. But the slow speed of silk printing is the biggest problem. The gravure printing can also achieve good results. To completely solve the problem of speed, the Gravure Engraving depth should be more than 55 nm In this way, the printing heat sensitive anti-counterfeiting ink will have a certain ink layer thickness It should also be noted that During the printing process, it is required to ensure that the thermal anti-counterfeiting ink can not use strong stirring and large ink tank and ink cylinder circulation, and the ink penetration can not be less than 30 seconds As offset printing and flexographic printing, the printing difficulty is increased due to the large particle size of the ink. The main reason is that there are relatively few types of this ink. At the same time, the color is very light after one printing, which is difficult to meet the design requirements of the cigarette label. The solution is generally to increase the proportion of the color paddle, or to repeat printing twice. This poses a great restriction on the printing of heat sensitive anti-counterfeiting ink by offset printing and flexographic printing.

2. it is easy to sink Dianhe caking

the biggest problem in the use of heat sensitive anti-counterfeiting ink is that it is easy to precipitate and caking It causes a lot of inconvenience to use. Especially for water-soluble inks, if they circulate or stand still in the ink tank, the ink will soon form sediment. If they are old inks reused overnight; The caking problem can be quite serious. At this time, it is necessary to stir again and add a certain proportion of pure water Ensure that the viscosity of the ink on the line after the use of filtration. Solvent - based is better than water - soluble However, sedimentation and caking are also serious after long-term storage

3. Market management has yet to be standardized

as a heat sensitive anti-counterfeiting printing, it mainly plays the role of product anti-counterfeiting. However, as a source of heat sensitive anti-counterfeiting ink, market management is not standardized enough, especially for a cigarette label anti-counterfeiting ink, which can be easily purchased by many printing enterprises. This has left a considerable amount of hidden benefits for heat sensitive anti-counterfeiting. As a result, it can be standardized at the market source of heat sensitive anti-counterfeiting ink, The anti-counterfeiting efficiency of thermal anti-counterfeiting can be improved to a greater extent

development direction of thermal anti-counterfeiting

1 Development direction of water-soluble heat sensitive inks at present, the heat sensitive anti-counterfeiting inks used more are still water-soluble. Although they have become the mainstream, they have not met the requirements of ink development, especially the current detection of environmental protection performance and odor residue of cigarette label products Solvent based ink is difficult to meet the requirements of cigarette label printing. As a high price thermal anti-counterfeiting ink, it should take the development path of water-based ink

2. Add color types of thermal anti-counterfeiting inks

the color types of thermal anti-counterfeiting inks are still relatively simple and limited to common red, blue, black and other colors. The types of ink colors are not rich enough: the color concentration of the ink is lighter than that of the common ink, which can not meet the requirements of one-time printing, and the black ink is not black enough Looks more like gray, red is not enough red, looks more like magenta; The granularity of the ink is still too large, and the printing effect is rough; These factors also restrict the use of heat sensitive anti-counterfeiting inks to a large extent, which requires the development of anti-counterfeiting inks that can provide more colors, so that heat sensitive anti-counterfeiting really reflects the grade of products

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