The cigarette package is hot and the printing process is "unique" operation experience sharing!
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The so-called hot stamping is a process of first stamping and then printing on the surface of hot stamping. The hot stamping in the hot stamping process is generally a partial hot stamping. The electro-aluminized aluminum used generally has a large contrast with the paper base color, so that the hot stamping portion and the other portions have a sharp contrast. For example: usually in white cardboard, glass cardboard hot stamping gold, silver, laser anodized aluminum, hot stamping laser aluminum on gold, silver cardboard, hot stamping gold, silver anodized aluminum on laser cardboard; printing UV offset printing is generally used.
Hot stamping is a high-tech emerging process that faces more and more complex problems than traditional processes. Especially in the absence of more practical experience for learning, most of the cigarette printing companies that have used the hot stamping process have experienced a tortuous process, and then gradually formed some uniqueness in the continuous exploration and summary. Experience and experience. Here, the author talks about his experience based on his practice of hot stamping and printing.
Large area hot stamping
Due to the need to print on the hot stamping surface, the hot stamping part of the hot stamping process mostly uses large-area hot stamping. Therefore, in the hot stamping equipment, the first hot stamping process is the round round and round flat automatic hot stamping machine. These two devices are better able to meet the large-area hot stamping requirements because of the line pressure. The pressure is relatively balanced and the total pressure is small, which is very suitable for the hot stamping process. However, the limitations of the two types of bronzing equipment are also obvious: the cost of round stamping is higher, and the efficiency of round stamping is relatively low. Therefore, most domestic cigarette pack printing enterprises use flat-press automatic hot stamping machines.
It is worth noting that in the process of hot stamping large-area field products, it is difficult to discharge the air in time, and it is difficult to adjust the same hot stamping plate when the pressure is uneven. In response to this problem, we must improve from the following aspects: First, the hot stamping version can best make the appropriate arc according to the "middle height, low ambient temperature", so that the air can be discharged in time during the hot pressing process; secondly, it should be selected Degree and tightness are suitable for large-area hot stamping and easy transfer of anodized aluminum; finally, in the adjustment of the plate according to the hot stamping version of "middle height, low ambient" characteristics of pressure compensation, commonly known as "Pagoda style bottom", Avoid obvious pressure "faults" at the junction of hot stamping and non-hot stamping, affecting ink transfer and adhesion. Generally, after the first hot stamping and printing, the edge of the hot stamping image needs to be pressed, bumped, or stamped. If the concave and convex pressure fault is formed, it will directly cause the pressure unevenness and hot stamping. Equal quality issues that are extremely difficult to handle.
Hot stamping
In the hot stamping process, especially large-area hot stamping often requires higher temperature and pressure. It is easy to wrinkle and break the paper during production, and there is a hot stamping phenomenon. In order to achieve the desired hot stamping effect, firstly, the actual production situation should be fully considered in the development and design of the cigarette pack, and the hot stamping area should be avoided as much as possible; secondly, the paper with higher surface strength and the easy-to-peel enamel should be selected, otherwise it should be treated. It will get twice the result.
Bad printing
In the process of hot stamping, many times the hot stamping process is carried out very smoothly, but in the printing process, problems such as back-drawing, ink loss, and poor adhesion are frequently encountered.
There are two reasons for the printing reverse pulling: First, the adhesion of the electro-aluminized aluminum in the hot stamping process is insufficient, which can be solved by appropriately increasing the pressure, increasing the temperature or replacing the electrochemical aluminum; secondly, the offset viscosity or the embossing pressure of the offset printing ink is too large. The process should be adjusted accordingly from the perspective of offset printing. It is unscientific to find that the printing reverse pulling requires the hot stamping process to increase the hot stamping pressure without restriction, because the hot stamping pressure will inevitably lead to the hot stamping position. The deformation of the depression causes problems such as imaginary printing ink layer, inaccurate printing, and defective printing and printing. It does not meet the printing quality requirements, and it also has an adverse effect on the post-press processing. Under normal circumstances, the setting of hot stamping pressure should be based on the paper without obvious dents and indentations.
In the first hot stamping process, there are two reasons for the phenomenon that the adhesion of the printing ink is not strong, the printing of the graphic part is lightly wiped, or even the ink is dropped into pieces. There are two main points: one is the electrochemical aluminum and the printing ink. There is a problem with matching. "There is no best, only the best match." Before the production application, we should actively look for matching inks and anodized aluminum. Second, because the electrochemical aluminum is not as strong as the paper to the offset ink, in the aluminum Printing, once the ink layer is too thick or the UV lamp power is not enough, the ink will be extremely difficult to completely cure, resulting in poor adhesion of the printed offset ink layer, which is easy to scratch, stick, or even fall off. For the latter reason, the solution is: in addition to the fine-grained UV ink with strong adhesion and good curability, it is also advisable to adopt the method of “deep ink thin printing”, which is to appropriately adjust the hue of the printing ink and reduce the ink layer. . This can achieve the desired printing effect and ensure the rapid curing of the ink layer. If the cigarette pack has already been printed, the only way is to extend the placement time so that it will dry naturally before proceeding to the next step.
Hot stamping positioning check
There are two kinds of hot stamping processes: one is to directly stamp on unprinted paper, and then to offset and other post-processing, such as the world show (gold) cigarette pack. The other is to first print the color of the main body of the cigarette pack, perform hot stamping according to the printing color position, and then perform UV offset printing and other post-processing on the surface of the hot stamping pattern, such as a small panda (Red Century Wind) cigarette pack. Since the latter process has printed graphics as a reference, it is easy to find out if the hot stamping process is in place. However, there is no obvious and fixed set of requirements for the hot stamping process in the first hot stamping process. How to check whether the hot stamping position is deviated during the hot stamping process? How to judge whether the invisible "hot stamping rule line" has a slight beat? Generally, when the hot stamping process starts normal production, we can use a blank film to jog a hot stamping, transfer the hot stamping image to the film completely, and then fix the hot stamped film on the sample stand. , paste the positioning block in its front gauge and side gauge position. During the inspection, the large-sized cigarette packets that have been stamped are positioned with three positioning blocks, and then compared with the film. Whether there is a hot stamping position or a standard beating will be clear at a glance, in order to avoid hot stamping After the secondary friction, it can be protected by sticking a large piece of transparent tape on the hot stamping on the film.
Hot stamping
Due to the particularity of the process itself, the steps and methods of the common process signature cannot be completely copied when the hot pack is printed after the hot stamping.
First of all, before the hot stamping sample, in addition to referring to the regular signing procedure, the hot stamped product must be overprinted once to confirm whether it will cause a reverse pull, and then the hot stamping pressure is signed. Secondly, since most of the hot stamping and printing cigarette packs have very high requirements on the registration accuracy, if there are conditions, the offset printing equipment is best to carry out the loading work simultaneously, and test printing is performed before the hot stamping sample production, confirming the printing and ironing. Whether the printed position meets the requirements. If there is overprint deviation in the position of the individual bronzing plate, the bronzing plate of the deviation position should be properly adjusted before the batch production, and try to avoid changing the position of the bronzing plate in the middle.
The hot stamping process has been widely used in many cigarette brands in many tobacco companies across the country. Different cigarette pack printing companies have different or even opposite views on some of the problems in the hot stamping process. This aspect is due to the fact that each cigarette pack printing company has its own different software and hardware environment and focus, and the operation methods are not the same. On the other hand, there are certain contradictions in many aspects of the hot stamping process. Contradiction between ink curing and paper deformation. Personally think that there is no difference between right and wrong here, lost in the east, and received the mulberry. The key lies in the right medicine and the "degree".