With the improvement of national economy and the development of printing and packaging industry, people require high-grade, exquisite, environmentally friendly and personalized packaging. In the post-press processing of packaging products, anodized hot stamping technology is loved by people because of its unique surface finishing effect, and is applied to high-end packaging such as banknotes, cigarette labels, medicines and cosmetics. Anodized aluminum hot stamping refers to the hot stamping process of hot stamping materials such as hot stamping and silver stamping. In order to facilitate discussion, we will use bronzing as a general term for anodized hot stamping. There are two main functions of bronzing, one is surface decoration to improve the added value of products. It is our national tradition to love happiness and glory, and the combination of bronzing and embossing technology shows its luxury; The second is to endow the product with high anti-counterfeiting performance, and adopt holographic positioning hot stamping trademark logo to prevent counterfeiting and protect famous brands. At the same time, bronzing can reflect the personalization of product packaging, safety and environmental protection. So many high-end packages adopt bronzing technology, so how to improve the bronzing quality? This paper discusses it from the following aspects. First, the bronzing version of high-quality bronzing version is the primary factor to ensure the quality of bronzing. At present, photographic etching process and electronic engraving technology are mainly used to make bronzing plates, and copper plates or zinc plates are often used as materials. Copper plate is fine in material, and its surface smoothness and heat transfer effect are better than zinc plate. The use of high-quality copper plate can improve the gloss and outline clarity of bronzing graphics and texts. The traditional photo etching technology is simple and low cost, and is mainly used for characters, thick lines and general images. For the fine bronzing plate with uneven graphic thickness, it is necessary to use the secondary rotten depth or electric engraving technology. The bronzing plate made by electric carving can show rich and delicate level changes, which greatly expands the packaging performance. This process is beneficial to environmental protection, but the investment in electric engraving equipment is large, and the current engraving depth is not ideal, which is easy to cause bronzing "paste board". Holographic anti-counterfeiting bronzing plate has high technical requirements. Previously, it was mainly made in Taiwan Province Province or abroad, with a long plate-making cycle, and it was only used for the packaging of fixed and mass products. At present, there are several units in Yuncheng, Shanxi, Beijing and Shanghai. Second, bronzing equipment "If you want to do a good job, you must sharpen your tools first". The selection of bronzing equipment is the key factor to determine the quality of bronzing. There are three kinds of sheet-fed bronzing machines: flat bronzing machine, round bronzing machine and round bronzing machine. At present, the most widely used flat stamping machines are: TYM series die-cutting and stamping dual-purpose machines of Shanghai Yahua Printing Machinery Co., Ltd., TYMl020 automatic stamping die-cutting machine of Tangshan Yuyin Group Co., Ltd. and MK series automatic stamping die-cutting machine of Tianjin Youheng Machinery Industry Co., Ltd., with the highest stamping speed of 5000 sheets/hour. STEUER) FOLLJET FBRl04 bronzing machine of Steuer, Germany is the representative of round pressing. Adopting the design concept of offset press, the highest hot stamping speed can reach 65,438+00,000 sheets/hour, which is the fastest sheet stamping equipment in the world at present. Three hot stamping methods, namely, rotary stamping, rotary stamping and flat stamping, have their own advantages and disadvantages: rotary stamping and rotary stamping implement linear pressure, and the total pressure is small, so it is easy to complete large-area hot stamping with relatively small pressure, and the movement is stable. Moreover, the rotary press has high production efficiency and is especially suitable for stamping large quantities of live parts. However, due to the difficulty in processing the round surface of copper plate, the production cost is high, and the heating roller is also more difficult than the plane heating. The flattening operation is flexible and convenient, which is more suitable for short version products. Compared with imported bronzing equipment, domestic bronzing equipment has obvious advantages in performance and price. The price of domestic bronzing equipment is only 1/5 ~ 1/4 of the price of foreign similar products, but the overprinter accuracy, stability and function of imported machines are obviously better than those of domestic machines, and they are also more durable than domestic machines, which is more suitable for processing high-grade packaging products with fixed batches. Therefore, the product type and batch number are the key to determine the selection of bronzing equipment. Whether it has high-grade stamping die-cutting equipment such as BOBST has become the first choice for customers in the industry. Third, bronzing adaptability The so-called bronzing adaptability refers to the selection of anodized models and the matching of bronzing speed, temperature and pressure. Under the condition of fixed equipment and other hardware, mastering the bronzing adaptability correctly is the most important means to improve the bronzing quality. The following is an analysis of some quality problems reflected from the actual operation, so as to scientifically grasp the bronzing suitability. 1. Whether hot stamping can't go up or down is related to the surface characteristics of printed parts, the performance of anodized, hot stamping temperature and pressure. ① Excessive powder spraying on the surface of printed parts or additives such as adhesive remover and gloss paste on the surface will hinder the adsorption of anodized aluminum and paper. Solution: the solution in the process of surface powder removal or printing. ② Improper selection of anodized directly affects the bronzing fastness. We should consider what type of anodized to choose according to the size of bronzing area and the characteristics of hot stamping materials. Domestic anodized aluminum is mainly Peacock brand series produced by Shanghai Shen Yong Hot Stamping Materials Co., Ltd., while imported anodized aluminum is mainly PM and LK series in Kurtz, Germany, A, K and H series in Japan and SP series in KOLON, South Korea. According to our practice and test, the selection of anodized aluminum can mainly refer to the following categories: bronzing (general ink color) anodized aluminum on ordinary products has 88-L type and KURZ PM type; There are 88-2 kinds of thick ink printed matter (including gold and silver) such as cigarette packs and cosmetics. There are also 88-3, 88-4, PM288 and so on. Fine handwritten hot stamping for cigarette labels and cosmetic packaging. Suitable for paper covered with OPP or PET, cardboard with UV ink, glazing paper and other products. There are 88-4 anodized aluminum, K series, LK series and SP series. ⑧ The matching of hot stamping equipment and hot stamping time with hot stamping temperature is incorrect, which affects the fastness of hot stamping and the clarity of graphic outline. Due to the different equipment and hot stamping materials, the hot stamping time and temperature are also different. For example, the high-speed rotary printing machine is fast, the nip contact, and the hot stamping temperature will be higher than that of circular flattening or flattening. In general, the temperature of circular pressing is 190℃ ~ 220℃, the temperature of circular flattening is about 130℃ ~ 150℃, and the flattening temperature is about 100℃ ~ 120℃. Of course, hot stamping time, hot stamping temperature and production efficiency are also largely restricted by the transfer performance of anodized. 2. Reverse pulling refers to pulling away ink or varnish after anodized hot stamping. The main reason is that the ink on the surface of the printed matter is not dry or the UV post-treatment on the surface of the printed matter is improper, which leads to the poor combination of the ink and UV oil on the surface of the printed matter and the paper surface. Solution: Wait until the printed matter is dry before bronzing. In addition, anodized aluminum with low separation force and good thermal transfer performance can also be selected. 3. After hot stamping, the paste plate and anodized color-changing paste plate are mainly caused by poor production of hot stamping plate, loose installation of anodized or incorrect anodized film. The discoloration of anodized aluminum after hot stamping is mainly caused by high hot stamping temperature. In addition, the wrinkling of anodized aluminum is easy to cause uneven stacking and discoloration of hot stamping, which can be solved by lowering the temperature appropriately. For the circular flattening machine, a fan can be installed at the foil feeding place to keep the foil floating, so as to prevent anodized from contacting the bronzing plate and burning before hot stamping. 4. Improper process arrangement destroys the luster of anodic oxidation surface, and the graphic outline is weak. People are often worried that the gold foil is easy to be worn off and then covered with film, which is easy to cause: ① The film covering (especially the matte film) will destroy the luster of the anodized surface, so it is not suitable to cover it with water-soluble glue, otherwise it will cause the anodized surface to be black, and it is also easy to cause the gold powder to stick to the edge of the picture and text, resulting in weakness. ② After bronzing, it is sunken due to pressure, and the glue is not easy to penetrate into the anodized surface, which is easy to cause the separation of OPP and paper at the bronzing place and affect the product quality. The correct process is to cover the film before bronzing, and choose anodized matching OPP.