Bronzing process steps mainly include two steps: plate loading and hot stamping. Next, Hongsen packaging Xiaobian will tell you about it.
(1) Plate loading: copper plate is generally used for electrochemical aluminum hot printing plate, and its plate making process is the same as that of copper zinc plate for general relief plate. It adopts photographic plate making method, turns it into film, and then makes copper plate through corrosion and other processes, but it is required to be corroded deeper than general relief plate. The biggest difference between the plate loading of anodized hot stamping and relief printing is that the hot stamping plate should be installed on the electric heating plate, which is equipped with electric heating wire and heated during the hot stamping process.
(2) Printing and ironing: the first step in bronzing is to reasonably select electrochemical aluminum foil, which is one of the important factors to ensure the quality of hot stamping. In addition to the characteristics of electrochemical aluminum foil itself, the realization of the ideal transfer of electrochemical aluminum is also directly related to the three elements of electrochemical aluminum hot stamping. Therefore, we should reasonably determine the hot stamping temperature, hot stamping pressure and hot stamping time, that is, the three elements of hot stamping.
Bronzing processing temperature is too low will produce hot stamping or hot stamping is not firm. This is due to the insufficient melting of the isolation layer and adhesive layer of anodized aluminum. The hot stamping temperature must not be lower than the temperature resistance range of anodized aluminum. The lower limit of this range is to ensure the melting temperature of anodized aluminum adhesive layer. If the hot stamping temperature is too high, the hot-melt film will melt beyond the range, causing anodized aluminum to be attached around the imprint to produce paste, High temperature will also make the synthetic resin and dye in the anodized aluminum dyeing layer oxidized and polymerized. After hot stamping, the anodized imprint blisters or appears cloud like; In addition, high temperature will also lead to anodized aluminum layer and color layer surface oxidation, so that hot stamping products lose metallic luster, reduce brightness and dim color.
The factors to be considered in determining the hot stamping temperature are the model and performance of anodized aluminum, hot stamping pressure, hot stamping speed, hot stamping area, structure of hot stamping pictures and texts, color, thickness and surface area of the bottom color ink layer of printed matter, and the room temperature of the hot stamping workshop. When the hot stamping pressure is small, the machine speed is fast, the bottom color ink layer of printed matter is thick and the room temperature in the workshop is low, the hot stamping temperature should be appropriately increased. The range of hot stamping temperature is 70 ~ 180 ℃. After the temperature is completed, it should be able to remain constant from beginning to end, and the temperature difference should not exceed & plusmn as far as possible; 2 ℃ to ensure the stable quality of a batch of products.
The purpose of applying pressure on anodized hot stamping is to ensure that anodized can adhere to the substrate, and then shear the anodized hot stamping part. This process itself is a process of rapidly stripping anodized aluminum from the base film and transferring it to the substrate by using temperature and pressure. There are three forces in the whole hot stamping process: one is the stripping force of anodized aluminum from the base film layer; The second is the adhesive force between anodized and substrate; The third is the adhesion of the substrate surface. The pressure of hot stamping anodized aluminum is about 2.5 ~ 3.5Mpa.
When the hot stamping pressure is too small, the electrochemical aluminum cannot adhere to the substrate at the same time, and the edge of the hot stamping cannot be fully cut, resulting in the failure of hot stamping or the blotting of the hot stamping part. When the hot stamping pressure is too large, the compression deformation of the pad and substrate increases, resulting in thick paste imprinting.
The main factors affecting the hot stamping pressure are: hot stamping temperature, machine speed, the nature of anodized aluminum itself and the surface of the hot stamping object. Therefore, the above factors should be comprehensively considered when setting and adjusting the hot stamping pressure& mdash; Generally speaking, when the hot stamping temperature is low, the hot stamping speed is fast, the ink layer on the surface of the printed matter processed by hot stamping is thick and the smoothness of the paper is low. To increase the hot stamping pressure, on the contrary. The contact time between anodized and the substrate is determined by the hot stamping speed. The contact time is directly proportional to the hot stamping fastness under certain conditions. The bronzing processing speed is a little slower, which can make the anodized and the substrate bond firmly, which is conducive to hot stamping; When the machine speed increases and the hot stamping speed is too fast, the hot-melt film and falling off layer of anodized aluminum have not melted or melted sufficiently in an instant, resulting in no hot stamping or blotting. The hot stamping speed must adapt to the pressure and temperature. There are disadvantages from too fast to too slow. In actual operation, the operators usually regard the hot stamping speed as a constant and do not change it easily. After fixing the hot stamping speed, adjusting the hot stamping temperature and pressure will reduce the variables, simplify the operation and easy to control the quality. Generally, changing the hot stamping speed is considered only under special conditions.