A, printing bronzing paste on the surface to be bronzed; B, drying; C, covering the surface of the slurry with anodic aluminum oxide; D, heating and pressurizing the finished product with a roller bronzing machine; It uses modern means such as screen printing or computer inkjet printing to subvert the traditional plane layout process of packaging bronzing by heating and pressurizing the heat transfer metal plate for a hundred years.
In recent years, with the improvement of people's requirements for the appearance and quality of commodity packaging, printing technology and packaging technology have made great progress, and post-press processing technology has developed vigorously. As a part of post-press processing, anodized hot stamping has changed a lot in recent years. With the continuous emergence of new technologies and new processes and the combination of various technologies, packaging printed matter has achieved good results in gloss, three-dimensional, metallic and anti-counterfeiting performance after hot stamping, especially the three-dimensional hot stamping technology widely used at present, which makes the packaging of goods look high-grade, exquisite, gorgeous and full of personality.
At present, this technology is mainly used in greeting cards, bookmarks, trademarks, tobacco and alcohol packaging and various high-end packaging boxes.
Bronzing and three-dimensional bronzing
1. bronzing bronzing is a processing technology that presses printed matter and hot stamping plate together in a short time with the help of certain pressure and temperature, and transfers metal foil or color pigment foil to the surface of hot stamping material according to the graphic requirements of hot stamping template. Because hot stamping is mainly gold and silver, it is often called hot stamping. This technology is an important process to increase the visual effect and grade of labels, trademarks, cigarette packets, wine packets and various high-end packaging boxes. Technically, it can be divided into ironing before printing and printing before ironing. Hot stamping before printing is to hot stamp a layer of electrochemical aluminum foil on a blank substrate, and then print pictures and texts on the surface of the aluminum foil layer, which is mostly used for packaging printed matter that needs large-area hot stamping. Printing first and then hot stamping, that is, hot stamping the required pattern in the place where hot stamping is needed on printed matter, is a widely used process at present. From the way of hot stamping, it can be divided into hot stamping technology and cold stamping technology. Hot stamping technology is the above-mentioned hot stamping process that requires a certain temperature and pressure to complete the transfer of electrochemical aluminum foil. Cold stamping technology is a process of transferring electrochemical aluminum foil to the surface of packaging printed matter by coating UV glue on the part of printed matter that needs hot stamping. These two methods have their own characteristics and meet the requirements of different products. 2. Three-dimensional bronzing Three-dimensional bronzing technology is a composite technology combining bronzing technology and concave-convex embossing technology. It is a technological process that bronzing and embossing graphics and texts are made into female die intaglio and male mold relief with matching up and down by using corrosion or engraving technology, so that the bronzing and concave-convex embossing processes can be completed at one time. This process completes bronzing and embossing at the same time, which reduces the waste products caused by processing procedures and overprinting and improves productivity and product quality. Because three-dimensional bronzing is a combination of bronzing and embossing technology, the product effect is a relief-like three-dimensional pattern, which cannot be printed on it. Therefore, the process of printing first and then ironing must be adopted. At the same time, because of its high precision and high quality requirements, it is not suitable for cold stamping technology, but for hot stamping technology.
Three-dimensional bronzing technology and its characteristics
Three-dimensional bronzing technology is very different from ordinary bronzing, except that it can form embossed three-dimensional patterns, and it is different in plate making, temperature control and pressure control. 1. Plate-making (1) Ordinary hot stamping plates adopt high-quality hot stamping plates to ensure the quality of hot stamping. The production of ordinary hot stamping plate is relatively simple, mainly using photographic corrosion plate-making process and electronic engraving plate-making process. Commonly used plates are copper plate or zinc plate. Copper plate has become the mainstream hot stamping plate because of its fine texture, smooth surface, good heat transfer performance, wear resistance and pressure resistance, and difficult deformation. Using high-quality copper plate can improve the gloss and clarity of hot stamping pictures and texts. Zinc plate can also be used for some packaging printed matter with less hot stamping and low quality requirements. Photoetching plate making is a traditional manufacturing method with simple process, low cost and low precision, which is mainly suitable for characters, thick lines and images with low quality requirements. However, the hot stamping plate made by electronic engraving can enrich and refine the image level, and can reproduce fine lines and uneven pictures and texts well, but the relative cost is high. ⑵ The production principle of three-dimensional hot stamping plate is the same as that of ordinary hot stamping plate, but it is more complicated than ordinary hot stamping plate, because it needs to form three-dimensional relief pattern, and hot stamping plate is generally concave, and there are many shades, the depth is deeper than ordinary hot stamping plate and the accuracy is higher. At present, the photo etching method of copper plate is mainly used in China. This method has low cost and simple process, but it is only suitable for plane bronzing. Because of its poor stereoscopic impression, short service life and printing resistance of only about 65438+ 10,000 sheets, it is often used in some packaging products that do not require high relief effect. At present, it has been widely used to carve brass plates abroad. The pattern to be hot stamped is scanned by a scanner, and the data is stored in a computer. Then, under the control of computer and software, three-dimensional carving is carried out to form female die intaglio with rich three-dimensional patterns. Because it is controlled by computer, it can form very fine patterns, and the performance of fine parts is more ideal. The printing resistance can reach more than 6,543.8+0,000 prints, which is very suitable for making high-quality, large-print three-dimensional bronzing female die intaglio. Of course, due to the need to equip high-end electronic engraving machines, scanners, computers and software, engineers and technicians, etc. Its production cost is higher than that of photo etching method. It is precisely because of its complex production and technical difficulty that it can better prevent some illegal manufacturers from counterfeiting and has certain anti-counterfeiting function. Therefore, it is very suitable for some high-quality long-version products that need anti-counterfeiting function, such as cigarette packets, wine packets, health care products packaging, greeting cards and so on. In the past, this kind of hot stamping plate needed to be processed abroad, with high cost, untimely delivery and unsatisfactory design effect. At present, a few domestic manufacturers can process this kind of hot stamping plate, which effectively reduces the cost, especially the direct communication between the processing factory and the designer, which can correctly understand the design intention and obtain satisfactory results. ⑶ The three-dimensional stamping of bottom die relief is different from ordinary stamping. The bottom plate of ordinary hot stamping is flat and does not need to be specially made, but the bottom plate of three-dimensional hot stamping must be a convex relief corresponding to the hot stamping plate, that is, the concave part of the hot stamping plate should be convex on the bottom plate, and the convex height should correspond to the concave depth of the hot stamping plate. The method of making bottom die relief is the same as that of making male die relief by concave-convex embossing. Commonly used materials are gypsum and glass fiber. If gypsum is used, it must be made on a machine, so the process is complicated and it is troublesome to replace the bottom plate, but the cost is low, so it is widely used in China now. If glass fiber is used, it can be made in advance according to the model of bronzing plate, and the positioning hole can be made of processed copper plate, which is convenient for replacement and positioning. The bottom die relief is used to match the hot stamping intaglio to form a three-dimensional relief pattern, which must completely correspond to the hot stamping plate. However, three-dimensional stamping is different from concave-convex stamping. Most concave-convex bronzing does not need heating, while three-dimensional bronzing must be heated at high temperature. During hot stamping, with the increase of temperature, the hot stamping plate will expand, but the temperature of the bottom die relief is basically unchanged, which will cause the mismatch between the hot stamping plate and the bottom die relief, resulting in the phenomenon that the bottom die is crushed or cannot be hot stamped. Therefore, when making bottom die relief, we should fully consider the expansion rate of hot stamping plate in order to make accurate bottom die relief. 2. Technological requirements for three-dimensional bronzing (1) Electrochemical aluminum foil Electrochemical aluminum foil is generally composed of 4-5 layers of different materials, such as: base film layer (polyester film), peeling layer, colored layer (silver anodic aluminum oxide without colored layer), aluminum plating layer and adhesive layer. The main functions of each layer are as follows: ① The basement membrane layer mainly supports other layers. ② The function of the stripping layer is to separate the anodized aluminum foil layer from the base layer, which determines the transferability of the anodized aluminum layer. ③ The main function of the coloring layer is to display the color of anodized aluminum and protect the bottom layer. Common colors are: gold, silver, brownish red, light blue, black, red, green and so on. Among them, gold and silver are the two most commonly used. ④ The function of aluminized layer is to present metallic luster. ⑤ The function of adhesive layer is to bond hot stamping materials. Different adhesive materials make up the adhesive layer, and their adhesiveness is also different. In order to adapt to the different surface properties of different hot stamping materials, anodized will use different adhesive layers, thus forming different types of anodized. The speed and quality of hot stamping are mainly affected by peeling layer and adhesive layer. If these coatings are not sensitive to heat, the hot stamping speed will decrease accordingly.
In the past, due to the limitation of thermal transfer speed, the speed of flat hot stamping was low, reaching less than 5000 sheets/hour. But at present, some of the world's leading anodized suppliers have made their anodized products meet the requirements of the industry for hot stamping speed, and bost bronzing machine has achieved a hot stamping speed of 7,500 sheets/hour. Because three-dimensional bronzing forms a relief pattern, the control of temperature, speed and pressure is different from ordinary bronzing, so the requirements for bronzing gold foil are also different from ordinary bronzing. When choosing hot stamping foil, we should choose special hot stamping foil for three-dimensional stamping, instead of using ordinary hot stamping foil as three-dimensional stamping, otherwise the hot stamping quality will be poor or other unexpected phenomena will occur. ⑵ Temperature, pressure, speed, temperature, pressure and speed are the three elements of hot stamping technology. Only by controlling the relationship between them can we control the quality of bronzing, and so can three-dimensional bronzing. Because three-dimensional bronzing is to complete bronzing and embossing at one time, it requires higher temperature. Ordinary bronzing temperature is only 70℃ ~ 90℃, while three-dimensional bronzing can be completed at about 150℃. If the temperature is too low, the adhesive layer and peeling layer of anodized aluminum may not be completely melted, and the anodized aluminum foil cannot be completely transferred during hot stamping, resulting in hot stamping failure or exposure. However, if the temperature is too high, the paper will be excessively deformed, the pictures and texts will stick together, the handwriting will be unclear, and even the anodic oxidation will change color. At the same time, the hot stamping plate may expand too much because of the high temperature, and it cannot be accurately matched with the bottom die, resulting in poor hot stamping. So temperature control is the first of the three elements. Hot stamping pressure refers to the pressure on the layout of hot stamping plate at the moment of hot stamping. In the process of hot stamping, the melted anodized adhesive layer is transferred by pressure, so the pressure and uniformity directly affect the quality of hot stamping. Three-dimensional bronzing requires electrochemical aluminum foil to be transferred to the surface of printed matter, and the three-dimensional relief pattern should be pressed on the hot stamping part, which is very stressful, so the pressure is greater than that of ordinary bronzing, which requires that the strength of hot gold foil should be better and it can withstand the extrusion of strong pressure. Of course, this does not mean that the greater the pressure, the better, and it must be moderate. Too much pressure and too little pressure can't get beautiful patterns. Excessive pressure may crush the gold foil, even the bottom die and the printed matter to be ironed; However, if the pressure is too small, the transfer of hot gold foil is not complete or hot stamping can not be done, so that the three-dimensional relief of concave-convex pressure can not meet the quality requirements. Therefore, pressure control is also critical. Hot stamping speed is actually the contact time between hot stamping materials and anodized, that is, the heating time of anodized. The hot stamping speed is fast, the heating time is short, and the hot stamping temperature drops rapidly, which leads to the low temperature and the hot stamping fastness will be affected; Hot stamping speed is slow, heating time is long, hot stamping temperature drops slowly, and hot stamping fastness is good, but if it is not controlled well, hot stamping temperature will be too high. Therefore, the appropriate hot stamping speed is also the guarantee to obtain high-quality hot stamping effect. 3. Three-dimensional bronzing equipment Three-dimensional bronzing equipment usually has two types: flat pressing and round pressing, and round pressing is not suitable for three-dimensional bronzing. The flat and flat three-dimensional hot stamping equipment represented by Swiss bost equipment is developing in the direction of high speed, high precision and convenient use, and it is the main type of three-dimensional hot stamping.
Bost bronzing machine has reached the bronzing speed of 7500 sheets/hour, and its accuracy can be kept within 0. 1mm, making it one of the most advanced bronzing machines in the world. Rotary hot stamping is usually used for online processing of web. Because the circular pressing is in line contact, the bubble phenomenon that may exist in flat pressing can be completely avoided, with high speed and good quality. However, because the hot stamping plate and the bottom die relief plate are round, the processing is difficult and the cost is high, and the heat transfer effect of the round hot stamping plate is not very ideal, so it is not used much, and it is mostly used for some long editions with large output and high quality, such as cigarette packs, wine packs and health care products. Hot stamping and embossing are both traditional post-press processing technologies, which are indispensable processes in packaging and decoration. Now, the combination of them not only reduces the production process and improves the production efficiency, but also greatly improves the quality, decorative effect and anti-counterfeiting function of commodity packaging. Therefore, this technology now shows a strong development momentum. With the maturity of various conditions, it will gradually replace the original process of bronzing and embossing to form a three-dimensional gold pattern. Three-dimensional bronzing technology will become a very promising decoration technology in the field of post-press packaging and decoration.