Application of Thermal Anti-counterfeiting in Tobacco Printing
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Tobacco label printing is the representative of process innovation in the printing industry. The innovation in the field of anti-counterfeiting printing is very extensive. In order to prevent the counterfeiting of cigarettes, the anti-counterfeiting printing technology of cigarette labels can make ordinary consumers use the easiest method in the shortest time. Identify the authenticity of cigarettes. Electric code anti-counterfeiting technology, paper anti-counterfeiting technology and super-line multi-color overprinting are effective means of anti-counterfeiting printing. At the same time, the printing of special inks such as UV fluorescent ink, daylight color changing ink and thermal anti-counterfeiting ink (temperature change ink) has become the key to the anti-counterfeiting of cigarette printing. Especially the printing of thermal anti-counterfeiting ink is rich in color and close to the ordinary printing process. The printing cost is relatively low and the identification is easy to identify. There is a strong competitive advantage in the printing of cigarettes.
Principle of thermal anti-counterfeiting printing
Thermal anti-counterfeiting printing is the use of thermal anti-counterfeiting ink. It is printed in a special position that is easy to identify or printed into special characters or patterns. The change of the printed text or pattern is observed by the method of increasing the temperature to identify the authenticity of the product. The thermal anti-counterfeiting detection is convenient, rapid, accurate and simple. It does not need any special auxiliary instrument operators. It does not need special training to be practical and suitable for ordinary consumers. It has a wide range of applications in the field of cigarette printing.
1. Classification of thermal anti-counterfeiting inks
The thermal anti-counterfeiting ink refers to an ink which can print different characters or patterns according to different temperature regions in the case of temperature change. Simply speaking, it is an ink that can change color according to temperature. The color change temperature referred to here is 34 to 1000C. Generally, according to the temperature required for discoloration, it can be divided into hand-color discoloration anti-counterfeiting ink and high-temperature discoloration anti-counterfeiting ink: according to the effect after discoloration, it can be further divided into reversible and non-reversible color anti-counterfeiting ink: according to the difference of discoloration mode, it can be divided into single discoloration Reversible. Multi-color reversible single color discoloration irreversible and multi-color irreversible thermal anti-counterfeiting ink.
Hand temperature-changing anti-counterfeiting ink refers to an ink that can produce a text or pattern color change reaction in the temperature range of 34-360C: high-temperature color-changing anti-counterfeiting ink means printing text at 34c-1000C. even at higher temperatures. An ink in which a pattern can undergo a color change reaction.
The printed finished product displays a certain color at normal temperature. After heating, the printed text or pattern color disappears into no color. After the temperature is raised, it becomes another specific color, and immediately returns to the original color after cooling. The change process is reversible and can be repeated many times, so it is called reversible color ink; after increasing the temperature, it changes from colorless or from a specific color to another specific color, and the color displayed after temperature recovery does not disappear. Or recovery is called non-invertible color ink.
According to the difference in discoloration during high-temperature discoloration, it can be divided into single-color reversible, multi-color reversible, single-discolor irreversible and multi-discolor irreversible thermal anti-counterfeiting ink. The non-invertible color mode mainly has (in the case of 70-90C): from colorless to red, colorless to black, and the like. Reversible color change methods are: red becomes colorless, black becomes colorless, blue becomes colorless, etc. Of course, according to the design requirements of the cigarette mark, it can also be designed to become colored and other various colors.
2. The working principle of thermal ink
Thermal anti-counterfeiting inks rely primarily on dry thermochromic materials. Thermochromic substances can be classified into organic compounds and inorganic compounds, and can be subdivided into inorganic salts such as "coordination compounds, organic substances (dye molecules), and liquid crystal polymers.
1 Invertible color mechanism: As the temperature changes, the molecular structure of the thermochromic substance changes, that is, the electron donor and the electron acceptor move; the two spatial configurations or the two crystal structures change each other: the molecule The ink color changes due to thermal ring opening or free radical generation. The type of 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 changes. Therefore, when the heat source is removed, the color of the ink can be restored to its original state. For example, the pink liquefied diamond hexamethylenetetramine loses crystal water when the temperature rises to 35 ° C and turns into a sky blue. When the temperature drops, it absorbs the moisture in the air and returns to the original color. Another example is a red cube of mercury iodide (Hg:H912) which turns into a cyan orthorhombic crystal when heated to 137 ° C. After cooling to room temperature, it returns to the original cyan crystal.
2 Non-invertible color mechanism: When the thermochromic substance is heated, physical or chemical changes occur, and the original physicochemical properties are changed to produce a color change, so the ink color cannot be restored to the original color when the heat source is evacuated. For example: a distillate of nitriding penta-ammonia, which changes from room temperature pink to 120C purple 170C sky blue. Higher than 230C black, when cooled to room temperature, it still maintains the color corresponding to the highest temperature .
3. Thermochromic substances
The thermochromic substances that are truly compatible with the actual production of thermal anti-counterfeiting inks must meet the following three conditions:
1 High color sensitivity: The color printed in a short time during the detection process can change significantly, and the color contrast is high before and after color change.
2 The temperature range of the color change is appropriate: the color change temperature should be in the range of 40 to 100 ° C, which is mainly for the detection of the security ink.
3 good color stability: under different environmental conditions such as temperature, humidity, light intensity, etc., can achieve better color change effect and have relatively high sensitivity during the effective period of ink.
Application of thermal anti-counterfeiting on cigarette labels
Sensitive anti-counterfeiting is widely used on cigarette labels because it is easy to identify and can quickly identify the authenticity of the product by heating without destroying the outer packaging.
1. For special texts and patterns
In order to highlight the product's name, logo or icon. This is also the consumer's focus. The use of thermal anti-counterfeiting in these areas is also the most effective. By printing thermal anti-counterfeiting ink, not only can enhance the color effect of these characters or patterns but also pass the anti-counterfeiting. The recognition process enhances the consumer's impression of these proprietary text or graphics. In view of the effect of printing in the thermal anti-counterfeiting oil and the expensive price, the main text or the main body pattern of the product is usually applied to the English, Chinese pinyin or the theme pattern of the cigarette brand, so that not only the identification product can be achieved. The effect can also reduce the cost of cigarette label printing. Products using this method include "New Century Gold Leaf", "Red Hard Flower", "Special Drunk Flower" and other products.
2. For a specific area
This is mainly for the same type of products. Thermal anti-counterfeiting technology should be adopted in specific areas. The use of thermal anti-counterfeiting oil enables consumers to consciously and consciously identify the authenticity of products when purchasing similar products. Under normal circumstances, in the specific part of the clamshell part, the bottom part or the upper part of the cigarette label, these areas are not an important part of the cigarette label. By using the thermal anti-counterfeiting, the entire pattern can be dotted to facilitate the heating operation, and the uniformity of the same type of product is also convenient. The use of this method is "red hard gold Xuchang", "flower red hard red flag channel" and other products.
3. 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. At the time of design, attention should be paid to the coordination of the overall and partial patterns and colors. Ultimately, it will not only be easy for consumers to identify, but also promote the improvement of the entire cigarette standard.
Thermal anti-counterfeiting problems
1. Thermal anti-counterfeiting ink has large particle size and light color depth
The thermal anti-counterfeiting inks currently on the market also have the problems of large ink particle size and light color depth, which not only causes a rough printing effect, but also is not conducive to coordination with other color patterns. In general, the effect of screen printing is very good. The problem of thick layer and color depth is also solved. But the slow speed of screen printing is the biggest problem. Gravure printing can also get better results. The problem of speed is solved completely. The engraving depth of the gravure printing plate needs to be more than 55Nm. This will print a thermal anti-counterfeiting ink with a certain thickness of the ink layer. At the same time, it should be noted. In the printing process, it is necessary to ensure that the thermal anti-counterfeiting ink can not be used with strong agitation and a large ink tank and ink cylinder circulation ink drilling degree can not be less than 30 seconds "Coating No. 4 cup". As offset printing and flexographic printing, the printing difficulty is increased due to the large particle size of the ink, mainly because the type of the ink is relatively small, and the color is very shallow after printing, it 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 repeat the printing twice. This imposes significant constraints on offset printing and flexographic printing when printing thermal anti-counterfeiting inks.
2. Easy to precipitate and agglomerate
The biggest problem in the use of thermal anti-counterfeiting inks is that they are easy to precipitate and agglomerate. It causes a lot of inconvenience to the use. In particular, the water-soluble ink circulates or stands in the ink tank, and the ink quickly forms a precipitate. If it is an old ink that is used overnight, the agglomeration problem can be quite serious. At this time, it is necessary to re-mix and add a certain proportion of pure water. Ensure that the viscosity of the ink is filtered and used. Solvent-based is relatively better than water-soluble. However, long-term storage of precipitates and agglomeration is also quite serious.
3. Market management remains to be regulated
As a heat-sensitive anti-counterfeiting printing, it mainly serves as an anti-counterfeiting effect of products. However, as a source of thermal anti-counterfeiting inks, market management is not standardized enough, especially for a cigarette anti-counterfeiting ink. Many printing companies can easily buy such heat. Sensitive anti-counterfeiting leaves a lot of hidden benefits and can be standardized in the market of thermal anti-counterfeiting inks, which can improve the anti-counterfeiting performance of thermal anti-counterfeiting to a greater extent.
The development direction of thermal anti-counterfeiting
1. The development direction of water-soluble thermal ink
At present, more sensitive anti-counterfeiting inks are still water-soluble. Although they have become the mainstream, they have not yet met the requirements of ink development, especially the current detection of environmental performance and odor residue of cigarette labels. Solvent-based inks are difficult. To meet the requirements of the use of cigarette printing, as a more expensive thermal anti-counterfeiting ink, it should take the development path of water-based ink.
2. Increase the color type of thermal anti-counterfeiting ink
The color type of the thermal anti-counterfeiting ink is still relatively simple and is limited to ordinary red, blue, black and other colors of ink. The type of ink color is not rich enough: the color density of the ink is shallower than the ordinary ink color. The requirements of printing, black is not black enough. It looks more like gray, red is not red enough to look more like magenta; the graininess of the ink is still too large, the printing effect is still rough; these factors are still largely restricted With the use of thermal anti-counterfeiting inks, it is necessary to develop anti-counterfeiting inks that can provide more colors, so that thermal anti-counterfeiting truly reflects the grade of the products.
3. Further enhance the market management of inks
In order to further standardize the market of thermal anti-counterfeiting. To further consolidate its position in the anti-counterfeiting market and give full play to its backbone role in anti-counterfeiting printing, it should further regulate the market management of thermal anti-counterfeiting ink from the source. Especially the ink manufacturer should reflect Its anti-counterfeiting social function as a manufacturer of anti-counterfeiting products in the market makes it possible to play an anti-counterfeiting role from the ink market.