Analysis of the process requirements for three-dimensional bronzing in the post-press packaging field
In recent years, with the improvement of the appearance and quality requirements of commodity packaging, printing technology and packaging technology have made great progress, and the post-press processing technology has achieved vigorous development, while the electro-aluminized hot stamping
is used as a post-press. Part of the processing, the changes in the past few years are even greater. The continuous emergence of new technologies, new processes and a combination of various technologies has enabled the printed printed matter to achieve good results in gloss, three-dimensional, metallic and anti-counterfeiting properties after hot stamping
, especially at present. A wide range of three-dimensional hot stamping
technology makes the packaging of the goods look high-grade, exquisite and full of personality. At present, the technology is mainly used for greeting cards, bookmarks, trademarks, tobacco and alcohol packaging and various high-end packaging boxes.
Three-dimensional bronzing process requirements:
(1) Electrochemical aluminum foil
The electrochemical aluminum foil is generally composed of 4 to 5 layers of different materials, such as a base film layer (polyester film), a release layer, a colored layer (silver anodized aluminum has no colored layer), an aluminum plating layer, and an adhesive layer.
The main functions of each layer are:
The 1 base film layer mainly functions to support the other layers.
The function of the 2 peeling layer is to separate the electrochemical aluminum foil layer from the base layer, which determines the transferability of the electrochemical aluminum layer.
3 The main role of the colored layer is to display the color of the anodized aluminum and protect the underlayer. Common colors are: gold, silver, brown, light blue, black, red, green, etc., among which gold and silver are the two most commonly used.
4 The role of the aluminized layer is to present a metallic luster.
5 The role of the adhesive layer is to bond the hot stamping material.
The adhesive materials constituting the adhesive layer are different, and the adhesiveness is also different. In order to adapt to the different surface properties of different hot stamping materials, the electrochemical aluminum will use different bonding layers to form different types of anodized aluminum.
The hot stamping speed and quality are mainly affected by the peeling layer and the adhesive layer. If these coatings are not sensitive to heat, the hot stamping speed will be reduced accordingly. In the past, due to the limitation of heat transfer speed, the flat stamping speed was lower, which was less than 5,000 sheets per hour. However, some of the world's leading suppliers of anodized aluminum have made the production of anodized aluminum sufficient for the industry. Printing speed requirements, Swiss Bobst hot stamping machine has achieved a hot stamping speed of 7,500 sheets / hour. Since the three-dimensional bronzing forms an embossed pattern, the control of temperature, speed and pressure is different from that of ordinary bronzing. Therefore, the requirements for hot stamping foil are also different from ordinary bronzing. When using hot stamping foil, it should be used for stereo hot stamping. Hot stamping foil, but can not use ordinary hot stamping foil as a three-dimensional hot stamping, otherwise it will produce poor quality or other unexpected phenomenon.
(2) temperature, pressure, speed
Temperature, pressure and speed are the three major elements of hot stamping technology. Only by controlling the relationship between the three can control the quality of hot stamping. Since the three-dimensional bronzing is a gilding and embossing at one time, the temperature requirement is higher, the ordinary bronzing temperature is only 70 ° C ~ 90 ° C, and the three-dimensional bronzing can be completed at about 150 ° C. If the temperature is too low, the electrochemical aluminum adhesive layer and the peeling layer may not be fully melted, and the electroformed aluminum foil may not be completely transferred during hot stamping, resulting in hot stamping or exposure. If the temperature is too high, the paper will be over-deformed, the image will be confusing, the writing will be unclear, and even the phenomenon of discoloration of the electrochemical aluminum will occur. At the same time, the hot stamping plate may expand too much due to the high temperature, but it cannot be accurately and bottomed. The mold is combined to produce a bad stamping phenomenon. Therefore, temperature control is the first of the three major factors.
Hot stamping pressure refers to the pressure on the hot stamping plate. In the hot stamping process, the melted anodized aluminum adhesive layer is pressed to complete the transfer of anodized aluminum, so the magnitude and uniformity of the pressure directly affects the quality of the hot stamping. In addition to the requirement that the electro-aluminized foil is transferred to the surface of the printed matter, the three-dimensional gilding also uses a large pressure to press the three-dimensional embossed pattern on the hot stamping part, so the pressure is greater than that of ordinary hot stamping, which requires the strength of the hot stamping foil to be better. With a crush that can withstand strong pressure. Of course, this is not to say that the bigger the pressure, the better. It must be appropriate. If the pressure is too large or too small, you can't get a beautiful pattern. Excessive pressure may crush the hot foil and even crush the bottom mold and the printed matter to be burned; if the pressure is too small, the transfer of the hot foil may be incomplete or hot stamping, so that the three-dimensional relief of the concave and convex is not achieved. Quality requirements. Therefore, pressure control is also critical.
The hot stamping speed is actually the contact time between the hot stamping and the electrochemical aluminum, that is, the heating time of the electrochemical aluminum. The hot stamping speed is fast, the heating time is short, the hot stamping temperature drops rapidly, the temperature is too low, the hot stamping fastness is affected; the hot stamping speed is slow, the heating time is long, the hot stamping temperature is slow, and the hot stamping fastness is good. However, if the control is not good, the hot stamping temperature will be too high. Therefore, a suitable hot stamping speed is also a guarantee for obtaining a high quality hot stamping effect.
Bronzing and embossing technology are traditional post-press processing technologies, which are indispensable processes in packaging and decoration. Now the two are used together, which not only reduces the production process, but also improves the production efficiency. The decoration effect and anti-counterfeiting function have been greatly improved. Therefore, this technology now shows a strong development momentum. As various conditions mature, it will gradually replace the process of forming a three-dimensional gold pattern by two processes of bronzing and bump imprinting. The three-dimensional bronzing process will become a very promising decoration technology in the field of post-press packaging and decoration.