How to control the quality of Cigarette Box packaging combination process?
Feb 24, 2022
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How to control the quality of Cigarette Box packaging combination process?
In recent years, with the intensification of competition in the tobacco industry, the increase of external pressure on tobacco control and the improvement of people's aesthetics, people have become more and more demanding on the quality of Cigarette Box, which also promotes the continuous improvement of the design level of Cigarette Box. In order to highlight the brand personality and achieve special design and decoration effects, the combination process is increasingly applied to the field of Cigarette Box printing.
The "Septwolves" (blue) Cigarette Box printed by a company adopts the combination process of "ordinary offset printing + gravure printing + hot stamping + UV offset printing + embossing + embossing hot stamping + die cutting". The specific production process is: ordinary offset printing (three-color blue) → single-sheet gravure printing (silver text) → hot stamping (bottom silver) → UV offset printing (two-color gradient blue) + water-based varnish → embossing → embossing hot stamping (outer frame of Septwolves Logo) → mold cut.
Below, the author will take the 7 processes in the above combination process as an example, and discuss the key points of the quality control of the combination process of Cigarette Boxs with colleagues.
1. Ordinary offset printing (three-color blue)
The three-color blue that needs to be printed in this process are shading blue, gradient blue and dark blue. The ink color of the three-color blue superimposed part is difficult to control, and the different shades can easily cause color difference. In the process of offset printing, it is required to control the ink color within the upper and lower limits of the standard sample, and △E≤1.5, and always pay attention to the occurrence of quality problems such as ink skin, water rejection, ink rejection, scratches, back dirty, and powder drop. Considering that there is no glazing on the surface of the printed product during the first offset printing, and the tri-color blue ink will turn red after drying, so this process needs to use a spectrophotometer to measure the L, a, and b values of the tri-color blue. And use this as the basis for investigating the change of its ink color. In addition, allow enough time for the ink to dry to avoid quality hazards (such as nozzle marks) in the next gravure printing process.
2. Sheet-fed gravure (silver text)
Gravure printing has two main disadvantages: first, the plate-making process is complicated and the price is high; second, most of the gravure inks currently contain toluene-based solvents, and toluene-based solvents not only pollute the environment, but also are harmful to the human body, so a large number of packaging is required. Printing companies are under control. In the gravure printing process, in order to obtain better printability of the gravure ink, it is usually necessary to add some solvents, such as slow drying agents, additives for adjusting the performance of the ink, etc. The addition of these solvents will affect the VOC of the Cigarette Box. Residues have a certain impact. Therefore, in the gravure printing process, it is forbidden to add isopropanol, n-butanol and other solvents with poor volatility to the gravure ink. Even if the solvent within the allowable range is added, it must be strictly implemented in accordance with the process regulations. In addition, matching ventilation equipment must be installed in the printing workshop.
In this process, the operator also needs to pay special attention to controlling the viscosity of the ink, otherwise it is prone to text tailing, mottled, etc.; pay attention to the thickness of the text, burrs, etc.; Add small amount of ink many times to maintain the stability of the ink layer of the printed product.
3. Hot stamping (bottom silver)
In this process, the registration accuracy of the hot stamping pattern (compared with the film), hot stamping fastness and color are mainly checked (pay attention to control the temperature, if the temperature is high, the surface color of the printed product is easy to darken, and also pay attention to the bottom silver There should be no defects and burns). In addition, the hot stamping pressure should be moderate, and the pressure will affect the quality of the subsequent UV offset printing.
Among them, the hot stamping fastness is one of the most important parameters. Once the control is not good, the bottom silver will be pulled down by the UV offset printing ink during the subsequent UV offset printing, which will not only affect the quality of the Cigarette Box, but also the bottom of the reversely pulled down. Silver will also quickly accumulate on the blanket, causing the image dots to be lost in light, and in severe cases, partial images cannot be printed. And with the continuous operation of the equipment, the bottom silver powder will also be transferred to the ink roller ink transfer system to accelerate the wear of the ink roller. Therefore, in this process, according to the characteristics of the printing paper, the appropriate anodized aluminum should be selected to ensure that the bottom silver of the hot stamping can be firmly attached to the surface of the paper.
4. UV offset printing + water-based varnish
In the process of UV offset printing, pay attention to the phenomenon of pulling ink, incomplete graphics, scratches, and false printing. In addition, when glazing, the amount of varnish should be moderate, and care should be taken to avoid scratches, nozzle marks, and patterns. It should be noted that after glazing, the ink color printed in the first ordinary offset printing process tends to change to blue and yellow. Therefore, it is necessary to strictly control the ink color of the first ordinary offset printing process to avoid large color fluctuations after glazing.
5. Press the bump
When the shading of the Septwolves Logo is embossed, the pressure should be moderate, the line burst phenomenon should not occur, and the embossed plate and the bottom mold should not be dislocated.
6. Embossed hot stamping (outer border of Septwolves Logo)
The quality control of this process is a difficult point of the combined process, which belongs to "hot after printing, and then hot after printing". The following defects are prone to occur during processing.
(1) The burr sawtooth phenomenon. This phenomenon is a defect of the embossing process itself. Concave and convex hot stamping is the two processes of hot stamping and embossing at the same time, so the contact surface of the edge part is usually not very smooth, and it is difficult to keep the pressure uniform during the whole processing process. One of the quality problems, so such defects are prone to occur. The main control measures are: adjust the temperature and pressure of the hot stamping plate appropriately during the production process and reduce fluctuations; place the anodized aluminum for a period of time before hot stamping.
(2) The phenomenon of pulling ink. The main reason for this phenomenon is that the bonding force between the UV offset printing ink printed on the bottom silver and the anodized aluminum after hot stamping is poor, and the hot stamping process itself has a certain temperature and pressure, so the hot stamping is completed. When the anodized aluminum is peeled off the printed product, the ink will stick to the anodized aluminum instead, resulting in the phenomenon of ink pulling. Therefore, the key to controlling this process is to ensure that the bottom silver hot stamping must be firm.
7. Die cutting
During the die-cutting process of Cigarette Boxs, attention should be paid to checking whether there are problems such as rough cutting edges, improper indentation line pressure, inaccurate die-cutting specifications, and poor die-cutting registration accuracy.
The combination process of Cigarette Boxs should be based on the characteristics of various printing and processing techniques, develop strengths and avoid weaknesses, continuously accumulate experience, establish a suitable quality control model, stabilize the quality of Cigarette Boxs through process control, quality control, and standardization of operating procedures, and make good use of quality management tools , to improve the quality management level to adapt to the future development trend of the Cigarette Box printing industry.