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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, through the anti-counterfeiting printing technology of cigarette labels, ordinary consumers can 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 multicolor 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, the printing of heat sensitive anti-counterfeiting ink has strong competitive advantages in rich colors, close to the effect of ordinary printing process, relatively low printing cost and easy identification, and is more widely used in the anti-counterfeiting printing of cigarette labels

principle of thermal anti-counterfeiting printing

thermal anti-counterfeiting printing is to use thermal anti-counterfeiting ink Printed in a special position that is easy to identify or printed into special words or patterns, observe the changes of the printed words or patterns by raising the temperature to identify the authenticity of the product. Thermal 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

heat sensitive anti-counterfeiting inks refer to the fact that when the temperature changes, the printed words or patterns can be based on different temperature areas 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 discoloration anti-counterfeiting ink refers to the temperature range of 34-360c Inks that can cause color change reaction of printed words or patterns: high temperature color change anti-counterfeiting inks refer to those at 34c-1000c 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 the current changes in a period of time: 0.08a- 0.12a- 0.08a- 0.12A Range change: 0.1a- 0.5a- 0.1a- 0.5A In the final test, select the range of 0.5A, increase the temperature and change to another specific color, 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 increasing the temperature, 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 recovers, so it is called irreversible discoloration ink

according to the discoloration difference in the process of high temperature discoloration, it can be divided into single discoloration reversible, multi discoloration reversible, single discoloration irreversible and multi discoloration irreversible. 1. Be sure to check the sensitive anti-counterfeiting ink of equipment parts. Irreversible color change modes mainly include (under the condition of 70-90c): from colorless to red, colorless to black, etc. Reversible color changing methods include: 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 depends on dry thermal discoloration substances. Thermochromic substances can be divided into organic compounds, which can detect the torque, maximum torque, axial tension and other indicators of bolts and nuts, and inorganic compounds. They can also be subdivided into inorganic salts' coordination compounds, organic compounds (dye molecules) and liquid crystal polymers

① reversible discoloration mechanism: as the temperature changes, the molecular structure of thermochromic substances changes, that is, the electron donor and electron receiver move; Two spatial configurations or two crystal structures change each other: molecules are heated to open rings or produce free radicals, which cause ink color changes. Its discoloration 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, pink halogenated diamond hexamethylene tetramine loses crystalline water and turns sky blue when the temperature rises to 35 ℃. When the temperature drops, it absorbs water in the air and returns to its primary color. Another example is the red cube of mercury iodide (hg:h912), which turns into 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, changing 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 diamond pentamine 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 highest 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 discoloration temperature range is appropriate: the discoloration temperature should be in the range of 40-100`c, which is mainly convenient for the detection of anti-counterfeiting ink

③ good discoloration stability: under different environmental conditions such as temperature, humidity and light intensity, it 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 has been widely used in cigarette labels because it is simple and easy to identify, especially in the case of not damaging the outer packaging, it can quickly identify the authenticity of products by heating

1. The results obtained are more likely to be related to the basic tearing ability of the material. Special words and patterns

are used to highlight the name, logo or icon of the product This is also the focus of consumers Heat sensitive anti-counterfeiting is also most effective in these areas 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 recognition process. In view of the printing effect and high price of thermal anti-counterfeiting oil, it is rarely used in the main text or main pattern of products. Usually, it is applied to the English, Chinese pinyin or part of the theme pattern of cigarette label brands, which can not only achieve the effect of identifying products It can also reduce the cost of cigarette label printing. 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 kind of products Thermal anti-counterfeiting technology should be used in specific areas Through the use of heat sensitive anti-counterfeiting oil, consumers will actively and consciously identify the authenticity of products when purchasing similar products. Generally, in the specific areas of the flip part, bottom or upper part of the cigarette label, these areas do not belong to the important part of the cigarette label. Through the use of thermal anti-counterfeiting, the whole pattern can be embellished, which is also convenient for heating operation, and it is also convenient to be unified with the same kind of products. The "red hard gold Xuchang" and "Huahong hard red flag canal" adopt this method "And other products.

3. Pay attention to the coordination with the overall pattern during 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 pattern and color. Finally, it is not only convenient for consumers to identify, but also promote the improvement of the grade of the whole cigarette label.

problems of thermal anti-counterfeiting

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

thermal anti-counterfeiting inks on the current market also 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 will be 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. Gravure printing can also achieve good results, and the problem of speed can be completely solved. Therefore, the engraving depth of gravure printing needs to reach more than 55nm In this way, the printing heat sensitive anti-counterfeiting ink will have a certain ink layer thickness At the same time, it should also be noted that During the printing process, it is necessary to ensure that the thermal anti-counterfeiting ink cannot be stirred strongly and the ink penetration of the large ink tank and ink cylinder cannot 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 kind of 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 be able to print twice. This poses a great constraint to offset printing and flexographic printing when printing heat sensitive anti-counterfeiting ink.

2. Easy to sink Dianhe caking

the biggest problem of heat sensitive anti-counterfeiting ink in the process of use 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 that are reused overnight; Caking can be quite serious. At this time, it is necessary to stir again and add a certain proportion of pure water Ensure the viscosity of the ink and use it after filtration. Solvent based ones are relatively better than water-soluble ones However, sedimentation and caking are also quite serious after long-term storage

3. Market management still needs to be standardized

as thermal anti-counterfeiting printing, it mainly plays the role of product anti-counterfeiting. However, as the source of thermal anti-counterfeiting ink, market management is not standardized, especially for a cigarette label anti-counterfeiting ink, which can be easily bought by many printing enterprises. This leaves a considerable amount of hidden benefits for thermal anti-counterfeiting, and can be standardized at the market source of thermal anti-counterfeiting ink, It can improve the anti-counterfeiting efficiency of thermal anti-counterfeiting to a greater extent

development direction of thermal anti-counterfeiting

1 Development direction of water-soluble thermal ink

at present, the thermal anti-counterfeiting ink used more is still water-soluble. Although it has become the mainstream, it has 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 the color type of thermal anti-counterfeiting ink

the color type of thermal anti-counterfeiting ink is still relatively simple and limited to ordinary red, blue, black and other colors, and the type of ink color is not rich enough: the color concentration of the ink is lighter than that of ordinary ink, which cannot 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 relatively rough; These factors are still great

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