In China, one of the top grades of cigarettes is reflected in the packaging of cigarettes. This article intends to make an analysis of the current status of the domestic cigarette pack printing process, and do some research on its development trend. First, the commonly used materials and processes of cigarette pack printing When low-grade cigarette packs are adjusted to mid-to-high grade, the printing paper will generally turn from ordinary fibers to non-absorbent composite paper. There are two types of composite paper for cigarette packaging: aluminum foil composite paper (aluminum foil combined with cardboard), bright film (laser film) composite paper (bright film, laser film and glass cardboard composite).
When printing on laser card paper, UV ink is often used to increase the ink adhesion. The following are the issues to be noted in laser jam printing:
(1) In the production process of laser film, due to static electricity, black dots and dirty spots will inevitably appear. In order to cover up these defects and reflect the laser effect, it is usually necessary to add 20 when designing the cigarette printing process. % to 40% of white nets.
(2) The laser film has 12 μm PET film and 23 μm BOPP film. In order to ensure the molding effect and the smoke speed, a 12 μm PET film is usually used.
(3) In order to improve the gloss of cigarette packs, laser paperboards with aluminized layers facing outwards are often used, ie, laser paperboards composed of PET film and paper, but the aluminized layer is easily scratched when facing outwards. Be sure to pay attention.
(4) In die-cutting, in order to prevent burrs from appearing, a pattern peak knife may be used. Because PET film and paper are not bonded together, delamination often occurs during die cutting. Therefore, before the official production, it is necessary to carry out a small batch of packages on the package machine. In order to ensure the viscose effect, the height of the viscose gluing line at the life should be 23.7mm, and the density of the viscose gluing line should be increased. Second, the status of various printing process analysis Offset offset printing process should be said to be a more mature printing process. In particular, there is a set of standardized and data-based methods for printing on the level of printing.
However, cigarette pack printing is not only a reproduction of product gradation, it also involves a large number of spot color reproduction, such as a large area of ​​red field, gold and silver, pearlescent effects. Because spot colors, especially spot colors, have high requirements for saturation and brightness, offset printing is limited by the thickness of the ink layer when it is printed on the ground. In order to achieve the goal, the method of “deep first and then lightly†printing twice is usually adopted (design should be considered as possible to avoid emptying the text on the ground edition so as to avoid increasing the difficulty of overprinting). In addition, cigarette pack printing has higher requirements on the stability (consistency) of color. Offset printing ink is also relatively long due to the presence of ink emulsification. There are many factors affecting the stability of ink, and it is difficult to achieve the above requirements.
In order to meet the demand for high-grade cigarette pack printing, most printing manufacturers implemented UV process transformation on the offset printing press. The emergence of UV technology has fundamentally solved the problem of ink adhesion, friction resistance, and drying of composite paper printing products. The photosensitizers in the UV inks are exposed to UV light, the unsaturated bonds in the resin are opened, and cross-linking forms a network structure, which greatly improves the physical properties of the ink layer surface. As a result, some cigarette pack manufacturers have begun to use offset UV inks to print fine sand, gold, silver and other common offset printing processes that are difficult to achieve.
The PS plates, rubber rollers, and rubber blankets used in UV offset printing are different from normal offset printing. At the same time, the number of UV lamps, power, UV photosensitizer and other factors can affect the UV ink drying effect. In the arrangement of the color sequence, considering the different absorption of UV light by various colors, a printing sequence of white→black→cyan→yellow→red is often used. In addition, UV inks from different ink factories should not be mixed with each other. This should be paid special attention.
2. The development of flexo flexo printing abroad is in full swing, and the proportion in the printing market has also increased year by year. However, there are some domestic “acclaimedâ€. On the one hand, the reason is that the domestic market needs to strengthen the acceptance of flexographic printing; on the other hand, foreign packaging design has always been to enhance the visual effects with simple and neat color blocks and lines, while in China, packaging products have a large area. Spot colors and image design see more. At the same time, domestic flexo printing technology also has a big gap with foreign countries in terms of its supporting raw and auxiliary materials.
However, flexo printing is still very promising for cigarette packs with color patches, lines or medium-dusty notes. First, the narrow-format flexo presses introduced in China are mostly 6+1 color sets. The last color set is used for coating, which can exert the advantages of flexo printing on spot color printing; secondly, the current domestic flexographic platemaking plants have been exploring. A set of effective flexo platemaking process methods is basically available to meet the requirements of hierarchical printing. In addition, flexo printing with on-line indentation, hot stamping, die cutting and other workstations, high production efficiency. In addition, the use of water-based inks for flexographic printing can be a big issue in “environmental protectionâ€. The key now is to guide the market in identifying the flexographic products.
In the formulation process of the cigarette pack flexo printing process, the plate making process is determined according to specific process conditions such as paper smoothness, anilox roller parameters, ink gray balance data, etc.; in the printing process, due to the viscosity of aqueous ink, Dryness is affected by the pH value, so the pH value of the ink must be strictly controlled; considering that the flexographic printing dot enlargement is more severe than the offset printing, like the offset printing, the printing pressure must be adjusted to the minimum.
Some hints: (1) Since the ink is transmitted through the anilox roller, the amount of ink required for printing in the field and the gradation printing is not the same. Therefore, the same color in the field and the cable should be separately plated. (2) Since the angle of the anilox roller is mostly 60°, the screen angle of the gradation plate should avoid 60° to prevent moire. (3) Considering that the ink drying method is evaporation drying, in order to enhance the contrast, it is recommended to use the printing color sequence of K→C→M→Y, and then print spot colors. (4) As an anilox roller for flexo printing "heart", it must be able to meet the needs of cigarette pack printing.
3. Gravure gravure printing accounted for nearly 30% of the market in cigarette pack printing because of its high saturation, high contrast, high brightness, strong consistency, and high printing plate resistance.
Gravure cigarette pack printing process is relatively mature. The reason why “relative†is more mature is because: First, there are various types of gravure inks and papers, and the plate-making manufacturers do not and cannot develop a complete set of gray balance parameters and printing characteristics for each printing manufacturer; The plate-making factory mostly uses the sample proofs to evaluate the plate-making quality, but the actual printing conditions and the proofing process conditions are quite different. Due to the fact that the gravure cigarette packs are seen in the field, in the color blocks, and in the lines, the requirements for color management in the plate making are relatively unrestricted. Gravure printing process control is easier than offset printing and flexo printing.
The in-depth understanding of the gravure platemaking process by the cigarette pack printing plant helps to increase the success rate of the smoke plate. Specifically: (1) gravure is to express the level through the size and depth of the network, in order to improve the ink transfer rate, the field version is commonly used 37 ° flattened diamond dot, engraving needle angle of 130 °, the number of screen lines It is 70 to 75 lines/cm; when engraving small text, the angle of the engraving needle is 110°, and the number of lines added is 80 lines/cm. (2) For products with the same color in the field, small (reverse) text or lighter screen, the clarity of the text will be affected when the depth of the cell site is to be ensured during the process of plate making; The outlets are also different. The angle of the scraper is large, and the text and outlets are clear, but the actual ink layer is thin and the gloss is poor. On the contrary, the scraper angle is small, the text and dot are blurred, and the solid ink layer is thick and high in gloss; For the Hierarchical Edition, in order to increase the transfer rate of inks, a greater proportion of slow-drying agents are used, and a larger proportion of fast-drying agents are used in the field. Therefore, consider separating plates. (3) After the printing plate is made, it is necessary to carefully check its concentricity, balance, increment, etc., so as not to affect the printing overlay.
The cigarette pack has the requirements of abrasion resistance and high temperature resistance for printing inks (does not fade for 0.5 seconds at 150-160°C). There are usually two solutions. First, select high-temperature resistant inks (nitrocellulose resin is the preferred linking material because it meets this requirement); Second, select high-temperature resistant varnishes, which are often used in cigarette pack printing. The oil (with respect to the solvent-based varnish, the amount of the varnish is small, and the residual ethyl alcohol has a much lighter residual taste than ethyl acetate).
At the same time, the gravure ink must have high fluidity, good squeegee characteristics, good transferability, and dryness. Solvents are used in printing to adjust the viscosity and dryness of the ink. Because of the different solvents' solvency and volatilization rate (ethyl acetate evaporation rate> toluene> ethanol> isopropanol), mixed solvents are often used. During printing, as the solvent continues to evaporate, the balance of the mixed solvent is broken. Printing problems tend to occur at this time, and new solvents need to be continuously added. In addition, the requirement for the residual amount of the solvent in the cigarette pack is usually not more than 30 mg/m 2 .
As for the failures in the gravure printing of cigarette packets, it is necessary to comprehensively consider factors such as ink, printing plates, printing machines, squeegee, printing environment, solvents, and paper.
4. Silk screen printing made silk screens shine new vitality. Especially after UV modification, the effect of screen printing such as frosting, refraction, ice and wrinkles made the decoration of cigarette packs icing on the cake, which greatly stimulated consumers' desire to purchase. In addition, because the UV (local) gloss of the screen is high and the three-dimensional effect is strong, it is often used in cigarette packs.
To effectively represent the effect of screen UV printing, in the printing process, we must choose a screen mesh, sand and ink; strictly control the thickness of the photosensitive film, printing distance; UV lamp wavelength, power, drying time, etc. It also has an important effect on the final result.
Tips: (1) In the design of cigarette packs, the matte pattern should be 2 to 3 mm away from the indentation and die cutting position to avoid damaging the sand and ink during die cutting. (2) Considering the transparency of sand ink, text should not be trapped with sand and ink, and can be directly printed on gold or silver paper. (3) When the large area of ​​the field and the small text are the same color, in order to reduce the jagged effect of the text edge, separate screens of different meshes should be used.
5. The post-press processing of cigarette packs after printing usually includes hot stamping (embossing), embossing, die cutting, and the like. Because printing manufacturers do not know much about bronzing and embossing plates, they usually output offset film when the film is exported. Here, it is necessary to emphasize: 1 bronzing version of the negative direction; 2 positive and negative version of positive and negative convex map; 3 male and female models (resin version) negative reverse, than the original size of about 0.3mm; 4 hot stamping Embossed version with the hot stamping version, due to corrosion twice, the border should be protected with lines.
In order to reduce waste products, press and embossing and die-cutting molding processes are used as much as possible. For products that require both hot stamping and embossing on hot stamping patterns, electrical engravings can be produced using hot stamping, embossing and one-shot molding process. For batches of long-term products, sandwich plate templates can be used.
Third, the trend outlook 1. The development of direct plate making technology will greatly promote the improvement of offset printing, flexo printing, and gravure printing technologies, such as offset printing, flexo-printing with computer-to-plate, and gravure printing with digital engraving rollers. As the carrier needed for mass copying in packaging and printing, the printing plate cannot be eliminated. It will continue to advance with the development of computer technology.
2. UV ink with its high adhesion, non-volatile substances, no need to spray powder and many other advantages will guide the development trend of cigarette pack offset printing. Due to its own characteristics, gravure printing will steadily increase in the cigarette package printing market. Although the cigarette pack flexo will increase due to the above reasons, it will not be too large. Screen printing UV printing will get a wide range of applications.
3. Laser jams and UV inks will inevitably increase in demand as cigarette packs are adjusted.
4. A variety of process combinations will be the ideal way for cigarette pack printing. For example, when printing products with gradation, you can choose offset printing; when printing spot colors, gold and silver ink, you can use sheet-fed gravure printing. In China Print 2001, Heidelberger introduced a flexo + screen printing (all can be UV printing, color groups can be interchangeable) presses, but also on-line indentation, bronzing (pressure convex), die-cutting, directly out of the finished product.
In short, cigarette pack printing
When printing on laser card paper, UV ink is often used to increase the ink adhesion. The following are the issues to be noted in laser jam printing:
(1) In the production process of laser film, due to static electricity, black dots and dirty spots will inevitably appear. In order to cover up these defects and reflect the laser effect, it is usually necessary to add 20 when designing the cigarette printing process. % to 40% of white nets.
(2) The laser film has 12 μm PET film and 23 μm BOPP film. In order to ensure the molding effect and the smoke speed, a 12 μm PET film is usually used.
(3) In order to improve the gloss of cigarette packs, laser paperboards with aluminized layers facing outwards are often used, ie, laser paperboards composed of PET film and paper, but the aluminized layer is easily scratched when facing outwards. Be sure to pay attention.
(4) In die-cutting, in order to prevent burrs from appearing, a pattern peak knife may be used. Because PET film and paper are not bonded together, delamination often occurs during die cutting. Therefore, before the official production, it is necessary to carry out a small batch of packages on the package machine. In order to ensure the viscose effect, the height of the viscose gluing line at the life should be 23.7mm, and the density of the viscose gluing line should be increased. Second, the status of various printing process analysis Offset offset printing process should be said to be a more mature printing process. In particular, there is a set of standardized and data-based methods for printing on the level of printing.
However, cigarette pack printing is not only a reproduction of product gradation, it also involves a large number of spot color reproduction, such as a large area of ​​red field, gold and silver, pearlescent effects. Because spot colors, especially spot colors, have high requirements for saturation and brightness, offset printing is limited by the thickness of the ink layer when it is printed on the ground. In order to achieve the goal, the method of “deep first and then lightly†printing twice is usually adopted (design should be considered as possible to avoid emptying the text on the ground edition so as to avoid increasing the difficulty of overprinting). In addition, cigarette pack printing has higher requirements on the stability (consistency) of color. Offset printing ink is also relatively long due to the presence of ink emulsification. There are many factors affecting the stability of ink, and it is difficult to achieve the above requirements.
In order to meet the demand for high-grade cigarette pack printing, most printing manufacturers implemented UV process transformation on the offset printing press. The emergence of UV technology has fundamentally solved the problem of ink adhesion, friction resistance, and drying of composite paper printing products. The photosensitizers in the UV inks are exposed to UV light, the unsaturated bonds in the resin are opened, and cross-linking forms a network structure, which greatly improves the physical properties of the ink layer surface. As a result, some cigarette pack manufacturers have begun to use offset UV inks to print fine sand, gold, silver and other common offset printing processes that are difficult to achieve.
The PS plates, rubber rollers, and rubber blankets used in UV offset printing are different from normal offset printing. At the same time, the number of UV lamps, power, UV photosensitizer and other factors can affect the UV ink drying effect. In the arrangement of the color sequence, considering the different absorption of UV light by various colors, a printing sequence of white→black→cyan→yellow→red is often used. In addition, UV inks from different ink factories should not be mixed with each other. This should be paid special attention.
2. The development of flexo flexo printing abroad is in full swing, and the proportion in the printing market has also increased year by year. However, there are some domestic “acclaimedâ€. On the one hand, the reason is that the domestic market needs to strengthen the acceptance of flexographic printing; on the other hand, foreign packaging design has always been to enhance the visual effects with simple and neat color blocks and lines, while in China, packaging products have a large area. Spot colors and image design see more. At the same time, domestic flexo printing technology also has a big gap with foreign countries in terms of its supporting raw and auxiliary materials.
However, flexo printing is still very promising for cigarette packs with color patches, lines or medium-dusty notes. First, the narrow-format flexo presses introduced in China are mostly 6+1 color sets. The last color set is used for coating, which can exert the advantages of flexo printing on spot color printing; secondly, the current domestic flexographic platemaking plants have been exploring. A set of effective flexo platemaking process methods is basically available to meet the requirements of hierarchical printing. In addition, flexo printing with on-line indentation, hot stamping, die cutting and other workstations, high production efficiency. In addition, the use of water-based inks for flexographic printing can be a big issue in “environmental protectionâ€. The key now is to guide the market in identifying the flexographic products.
In the formulation process of the cigarette pack flexo printing process, the plate making process is determined according to specific process conditions such as paper smoothness, anilox roller parameters, ink gray balance data, etc.; in the printing process, due to the viscosity of aqueous ink, Dryness is affected by the pH value, so the pH value of the ink must be strictly controlled; considering that the flexographic printing dot enlargement is more severe than the offset printing, like the offset printing, the printing pressure must be adjusted to the minimum.
Some hints: (1) Since the ink is transmitted through the anilox roller, the amount of ink required for printing in the field and the gradation printing is not the same. Therefore, the same color in the field and the cable should be separately plated. (2) Since the angle of the anilox roller is mostly 60°, the screen angle of the gradation plate should avoid 60° to prevent moire. (3) Considering that the ink drying method is evaporation drying, in order to enhance the contrast, it is recommended to use the printing color sequence of K→C→M→Y, and then print spot colors. (4) As an anilox roller for flexo printing "heart", it must be able to meet the needs of cigarette pack printing.
3. Gravure gravure printing accounted for nearly 30% of the market in cigarette pack printing because of its high saturation, high contrast, high brightness, strong consistency, and high printing plate resistance.
Gravure cigarette pack printing process is relatively mature. The reason why “relative†is more mature is because: First, there are various types of gravure inks and papers, and the plate-making manufacturers do not and cannot develop a complete set of gray balance parameters and printing characteristics for each printing manufacturer; The plate-making factory mostly uses the sample proofs to evaluate the plate-making quality, but the actual printing conditions and the proofing process conditions are quite different. Due to the fact that the gravure cigarette packs are seen in the field, in the color blocks, and in the lines, the requirements for color management in the plate making are relatively unrestricted. Gravure printing process control is easier than offset printing and flexo printing.
The in-depth understanding of the gravure platemaking process by the cigarette pack printing plant helps to increase the success rate of the smoke plate. Specifically: (1) gravure is to express the level through the size and depth of the network, in order to improve the ink transfer rate, the field version is commonly used 37 ° flattened diamond dot, engraving needle angle of 130 °, the number of screen lines It is 70 to 75 lines/cm; when engraving small text, the angle of the engraving needle is 110°, and the number of lines added is 80 lines/cm. (2) For products with the same color in the field, small (reverse) text or lighter screen, the clarity of the text will be affected when the depth of the cell site is to be ensured during the process of plate making; The outlets are also different. The angle of the scraper is large, and the text and outlets are clear, but the actual ink layer is thin and the gloss is poor. On the contrary, the scraper angle is small, the text and dot are blurred, and the solid ink layer is thick and high in gloss; For the Hierarchical Edition, in order to increase the transfer rate of inks, a greater proportion of slow-drying agents are used, and a larger proportion of fast-drying agents are used in the field. Therefore, consider separating plates. (3) After the printing plate is made, it is necessary to carefully check its concentricity, balance, increment, etc., so as not to affect the printing overlay.
The cigarette pack has the requirements of abrasion resistance and high temperature resistance for printing inks (does not fade for 0.5 seconds at 150-160°C). There are usually two solutions. First, select high-temperature resistant inks (nitrocellulose resin is the preferred linking material because it meets this requirement); Second, select high-temperature resistant varnishes, which are often used in cigarette pack printing. The oil (with respect to the solvent-based varnish, the amount of the varnish is small, and the residual ethyl alcohol has a much lighter residual taste than ethyl acetate).
At the same time, the gravure ink must have high fluidity, good squeegee characteristics, good transferability, and dryness. Solvents are used in printing to adjust the viscosity and dryness of the ink. Because of the different solvents' solvency and volatilization rate (ethyl acetate evaporation rate> toluene> ethanol> isopropanol), mixed solvents are often used. During printing, as the solvent continues to evaporate, the balance of the mixed solvent is broken. Printing problems tend to occur at this time, and new solvents need to be continuously added. In addition, the requirement for the residual amount of the solvent in the cigarette pack is usually not more than 30 mg/m 2 .
As for the failures in the gravure printing of cigarette packets, it is necessary to comprehensively consider factors such as ink, printing plates, printing machines, squeegee, printing environment, solvents, and paper.
4. Silk screen printing made silk screens shine new vitality. Especially after UV modification, the effect of screen printing such as frosting, refraction, ice and wrinkles made the decoration of cigarette packs icing on the cake, which greatly stimulated consumers' desire to purchase. In addition, because the UV (local) gloss of the screen is high and the three-dimensional effect is strong, it is often used in cigarette packs.
To effectively represent the effect of screen UV printing, in the printing process, we must choose a screen mesh, sand and ink; strictly control the thickness of the photosensitive film, printing distance; UV lamp wavelength, power, drying time, etc. It also has an important effect on the final result.
Tips: (1) In the design of cigarette packs, the matte pattern should be 2 to 3 mm away from the indentation and die cutting position to avoid damaging the sand and ink during die cutting. (2) Considering the transparency of sand ink, text should not be trapped with sand and ink, and can be directly printed on gold or silver paper. (3) When the large area of ​​the field and the small text are the same color, in order to reduce the jagged effect of the text edge, separate screens of different meshes should be used.
5. The post-press processing of cigarette packs after printing usually includes hot stamping (embossing), embossing, die cutting, and the like. Because printing manufacturers do not know much about bronzing and embossing plates, they usually output offset film when the film is exported. Here, it is necessary to emphasize: 1 bronzing version of the negative direction; 2 positive and negative version of positive and negative convex map; 3 male and female models (resin version) negative reverse, than the original size of about 0.3mm; 4 hot stamping Embossed version with the hot stamping version, due to corrosion twice, the border should be protected with lines.
In order to reduce waste products, press and embossing and die-cutting molding processes are used as much as possible. For products that require both hot stamping and embossing on hot stamping patterns, electrical engravings can be produced using hot stamping, embossing and one-shot molding process. For batches of long-term products, sandwich plate templates can be used.
Third, the trend outlook 1. The development of direct plate making technology will greatly promote the improvement of offset printing, flexo printing, and gravure printing technologies, such as offset printing, flexo-printing with computer-to-plate, and gravure printing with digital engraving rollers. As the carrier needed for mass copying in packaging and printing, the printing plate cannot be eliminated. It will continue to advance with the development of computer technology.
2. UV ink with its high adhesion, non-volatile substances, no need to spray powder and many other advantages will guide the development trend of cigarette pack offset printing. Due to its own characteristics, gravure printing will steadily increase in the cigarette package printing market. Although the cigarette pack flexo will increase due to the above reasons, it will not be too large. Screen printing UV printing will get a wide range of applications.
3. Laser jams and UV inks will inevitably increase in demand as cigarette packs are adjusted.
4. A variety of process combinations will be the ideal way for cigarette pack printing. For example, when printing products with gradation, you can choose offset printing; when printing spot colors, gold and silver ink, you can use sheet-fed gravure printing. In China Print 2001, Heidelberger introduced a flexo + screen printing (all can be UV printing, color groups can be interchangeable) presses, but also on-line indentation, bronzing (pressure convex), die-cutting, directly out of the finished product.
In short, cigarette pack printing
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