Cigarette label printing as a representative of process innovation in the printing industry. Innovations in the field of anti-counterfeiting printing are very extensive. In order to prevent counterfeiting of cigarettes, the anti-counterfeiting printing technology of cigarette labels allows ordinary consumers to use the most convenient method in the shortest time. Identify the authenticity of cigarettes. Code anti-counterfeiting technology, paper anti-counterfeiting technology and super-color multi-color overprinting are effective means of anti-counterfeiting printing of cigarette labels. At the same time, the printing of special inks such as ultraviolet fluorescent ink, sunlight color-changing ink, and heat-sensitive anti-counterfeiting ink (temperature change ink) has become the key to the anti-counterfeiting of cigarette label printing. Especially the printing of heat-sensitive anti-counterfeiting ink is rich in color and close to the ordinary printing process. 1. The relatively low printing cost and easy identification have a strong competitive advantage in powder. It has a wider application in the anti-counterfeiting printing of cigarette labels.
The principle of thermal anti-counterfeiting printing
Thermal anti-counterfeiting printing is the use of thermal anti-counterfeiting ink. Printed in a special location that is easy to identify or printed into a special text or pattern, through the method of increasing the temperature to observe the changes of the printed text or pattern is used to identify the authenticity of the product. The thermal anti-counterfeiting detection is convenient, rapid, accurate, simple and does not shake. Any special auxiliary instrument operator does not need to undergo special training before it can be actually operated. It is suitable for ordinary consumers. It has a wide range of applications in the field of cigarette label printing.
1. Classification of thermal anti-counterfeiting ink
Thermal anti-counterfeiting ink refers to the ink that can display different color effects according to different temperature regions under the temperature change. Simply speaking, it is an ink that can change color according to temperature. The color change temperature here is 34 to 1000C. Generally, according to the temperature required for discoloration, it can be divided into hand temperature discoloration anti-counterfeiting ink and high temperature discoloration anti-counterfeiting ink: according to the effect after discoloration, it can be divided into reversible and irreversible color anti-counterfeiting ink: according to the difference in color change method, it can be divided into single color change Reversible. Multi-color reversible single-color irreversible and multi-color irreversible thermosensitive anti-counterfeiting ink.
Hand temperature color-changing anti-counterfeiting ink refers to the temperature range of 34-360C. Ink that can produce the discoloration reaction of printed text or pattern: high-temperature color-changing anti-counterfeiting ink refers to 34c-1000C. Even at higher temperature, printing text or Ink where the pattern can change color.
The printed product shows a certain color at room temperature. The color of the printed text or pattern disappears and becomes colorless after heating, or changes to another specific color after increasing the temperature, and immediately returns to the original color after cooling. Because of its The change process is reversible. It 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 will not disappear after the temperature is restored. Or recovery is called irreversible color ink.
According to the discoloration difference in the process of high-temperature discoloration, it can be divided into single color-changing reversible, multi-color-changing reversible, single-color-changing irreversible and multi-color-changing irreversible thermal sensitive anti-counterfeiting inks. The main non-reversible color methods are (under 70-90C conditions): from colorless to red, colorless to black, etc. The reversible color change methods are: red to colorless, black to colorless, blue to colorless, etc. Of course, according to the design requirements of the cigarette mark. It can also be designed to be colored to become various other colors.
2. The working principle of thermal ink
Thermal sensitive anti-counterfeiting inks mainly rely on dry thermal sensitive color-changing substances. Thermochromic substances can be divided into organic compounds and inorganic compounds, and can also be subdivided into inorganic salts' coordination compounds, organic substances (dye molecules) and liquid crystal polymers.
①Reversible color mechanism: due to the temperature change, the molecular structure of the thermochromic substance changes, that is, the electron donor and the electron receiver have moved; the two spatial configurations or the two crystal structures alternate: molecules The color of the ink changes due to ring opening or the generation of free radicals. The type of discoloration can be divided into sublimation, melting, thermal decomposition, oxidation and solidification reactions, mainly due to the loss of crystal water. Crystal form conversion or discoloration due to changes in pH. Therefore, the color of the ink can be restored to its original state after the heat source is eliminated. For example: pink hexamethylene tetramine, when the temperature rises to 35 ℃, it will lose crystal water and become sky blue. When the temperature drops, it will absorb the moisture in the air and return to its original color. Another example is red cubic mercury iodide (Hg: H912) which turns to blue orthorhombic crystals when heated to 137 ° C. After cooling to room temperature, it returns to the original blue cubic crystals.
â‘¡ Non-reversible color mechanism: When the thermosensitive color-changing substance is heated, physical or chemical changes occur, changing the original physical and chemical properties to produce a color change, so the ink color cannot return to the original color after the heat source is evacuated. For example: the dichloride of diamond pentaamine complex, it changes from pink at room temperature to purple at 120C and sky blue at 170C. Black above 230C, when cooled to room temperature, it still maintains the color corresponding to the highest temperature .
3. Thermochromic material
The heat-sensitive color-changing substance that really meets the actual production of heat-sensitive anti-counterfeiting ink must meet the following three conditions:
â‘ High sensitivity to color change: 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.
â‘¡The color change temperature range is appropriate: the color change temperature should be in the range of 40 to 100`C, which is mainly for the detection of anti-counterfeiting ink.
â‘¢Good color change stability: Under different environmental conditions such as temperature, humidity, light intensity, etc., it can achieve a good color change effect and has a very high sensitivity within the effective period of the ink.
Application of thermal sensitive anti-counterfeiting on cigarette label
Sensitive anti-counterfeiting has been widely used in cigarette labels because of its simple and easy identification, especially the ability to quickly identify the authenticity of the product by heating without damaging the outer packaging.
1. Used for special characters and patterns
In order to highlight the product name, logo or icon. This is also the focus of consumers. 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 words or patterns can also pass anti-counterfeiting The recognition process enhances the consumer's impression of these proprietary words or patterns. In view of the effect of printing in thermal anti-counterfeiting oil and the high price, it is rarely used for the main text or main pattern of the product. It is usually applied to the English, Chinese pinyin of the tobacco label brand or a part of the theme pattern, so that it can not only achieve identification production. The effect can also reduce the cost of cigarette label printing. Products using this method include "new century golden leaves", "red hard scattered flowers", "special drunk flowers" and other products.
2. For specific areas
This is mainly for the same type of products. The use of thermal sensitive anti-counterfeiting technology in specific areas. Through the use of thermal sensitive anti-counterfeiting oil, consumers will actively identify the authenticity of products when purchasing similar products. In general, in the specific area of ​​the flip part, bottom or upper part of the cigarette label, these areas are not important parts of the cigarette label. Through the use of thermal anti-counterfeiting, the entire pattern can be embellished, which is also convenient for heating operation, and it is also convenient to be unified with the same type of product. Products that use this method include "Red Hard Gold Xuchang" and "Hua Hong Hard Red Flag Canal".
3. Pay attention to the coordination with the overall pattern when designing
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 lighter. When designing, you should pay attention to the coordination of the overall and local patterns and colors. The ultimate goal is not only to facilitate consumers to identify, but also to promote the improvement of the entire cigarette standard.
Problems with thermal anti-counterfeiting
1. Thermal anti-counterfeit ink has large particle size and shallow color depth
The thermal anti-counterfeiting inks currently on the market also have the problems of large particle size and light color depth. This not only causes rough printing effect, but also is not conducive to coordination with other color patterns. In general, the effect of screen printing will be very ideal. The problems of thick ink layer and color depth have also been solved. But the slow screen printing speed is the biggest problem. Gravure printing can also obtain good results and completely solve the speed problem. The engraving depth of the gravure printing plate needs to be more than 55Nm. In this way, the printing of thermal anti-counterfeiting ink will have a certain thickness of the ink layer. At the same time, it is also necessary to pay attention to it. In the printing process, it is necessary to ensure that the thermal anti-counterfeiting ink cannot use strong stirring and the circulation of the large ink tank and ink tank can not be less than 30 seconds. As offset and flexographic printing, the difficulty of printing is increased due to the large particle size of the ink. The main reason is that there are relatively few types of this ink, and the color is very light after printing. The solution is generally to increase the proportion of the color paddle, or to be able to repeat the printing twice. This poses a great restriction on the printing of thermal anti-counterfeiting inks for offset printing and flexographic printing.
2. Easy to settle and agglomerate
The biggest problem of thermal anti-counterfeit ink in use is that it is easy to settle and agglomerate. It causes a lot of inconvenience to use. Especially for water-soluble ink, if it circulates or stands still in the ink tank, the ink will quickly form a deposit. If it is old ink that is used overnight, the problem of agglomeration will be quite serious. At this time, it is necessary to re-mix and add a certain proportion of pure water. To ensure the viscosity of the ink, use it after filtering. Solvent-based ones are relatively better than water-soluble ones, but precipitation and agglomeration are also quite serious after long-term storage.
3. Market management still needs to be regulated
As thermal anti-counterfeiting printing, it mainly plays the role of anti-counterfeiting of products, but as the source of thermal anti-counterfeiting ink, market management is still not standardized, especially for a cigarette label anti-counterfeiting ink, many printing companies can easily buy it to give heat Sensitive anti-counterfeiting has left a considerable amount of hidden information and can be standardized at the market source of thermal anti-counterfeiting ink, which 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, more thermal sensitive anti-counterfeiting inks are still water-soluble. Although they have become the mainstream, they have not yet met the requirements for ink development, especially the current detection of the environmental performance and odor residue of cigarette label products. Solvent-based inks are difficult To meet the requirements for the use of cigarette label printing, as a more expensive thermal anti-counterfeiting ink should take the development path of water-based ink.
2. Increase the color type of thermal anti-counterfeiting ink
The color types of thermal anti-counterfeiting inks are still relatively simple and limited to ordinary red, blue, black and other colors. The types of ink colors are not rich enough: the color density of the ink is lighter than the ordinary ink and it can not be reached once. The printing requirements are not black enough. It looks more like gray, and it is not red enough. Red looks more like magenta; the particle size of the ink is still too large. The printing effect is relatively rough; these factors are still largely restricted In order to use thermal anti-counterfeiting inks, it is necessary to develop anti-counterfeiting inks that can provide more colors, so that thermal anti-counterfeiting can truly reflect the grade of products.
3. Further enhance the ink market management
In order to further regulate 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, the market management of thermal anti-counterfeiting ink should be further regulated from the source. Especially ink manufacturers should reflect Its anti-counterfeiting social function as a manufacturer of anti-counterfeiting products in the market makes it possible to play the role of anti-counterfeiting from the ink market.
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