First, hot stamping is the primary factor to ensure the quality of hot stamping
At present, bronzing plates are mainly produced by photographic etching techniques and electronic engraving techniques. The materials are often used for copper plates or zinc plates. Copper plate material is delicate, surface finish, heat transfer effect are better than zinc plate, the use of high-quality copper plate can increase the bronzing graphic gloss and outline definition. The traditional photographic corrosion technology makes the bronzing plate process simple and low cost, mainly used for text, thick lines, general images; for the finer, uneven thickness of text and graphics, etc. need to use the second rotten or electric carving technology. Electric carving production bronzing version can express rich and delicate level changes, greatly expanding the performance of the packaging, the process is conducive to environmental protection, but the electric carving equipment investment is relatively large, the depth of the current sculpture is not ideal, easy to cause hot stamping "glue". Holographic anti-counterfeit stamping production technology requirements are relatively high. Previously, they were mainly produced in Taiwan or abroad, and the plate making cycle was long. It was only used for the packaging of fixed and large-volume products. At present, there are several units that can be produced in Shanxi Yuncheng, Beijing and Shanghai. gF7 China Design Online China Creative Design Portal
Second, bronzing equipment "workers want to do good, must first sharpen its device"
The selection of bronzing equipment is a key factor in determining the quality of bronzing. Sheetfoil hot stamping machine has flat pressing, round flat pressing and round pressing. There are three types of flat pressing machines at present. The main applications are: Shanghai Yahua Printing Machinery Co., Ltd. TYM series die cutting hot stamping two Machine, Tangshan Yuyin Group's TYMl020 automatic bronzing die-cutting machine, Tianjin Hengheng Machinery Industry's MK series automatic gilding die-cutting machine, the maximum bronzing speed of 5000 hours. The German Stoll FOLLJETFBRl04 hot stamping machine is represented by a round press circle. Using the design concept of an offset press, the maximum hot stamping speed can reach 10,000 hours. At present, it is the fastest equipment for the international single sheet hot stamping. Round press, round press and flat press Three types of embossing hot stamping machines have their own advantages and disadvantages: Round press round and round press Hot press implementation is line pressure, total pressure is small, easy to complete with relatively small pressure A large area of gilding in the field, smooth movement, and high round-round production efficiency, especially for large quantities of live stamping, but due to the difficulty of copper circular surface processing, higher production costs, heating roller than flat heating is difficult. Flat press operation is flexible and convenient, and it is more suitable for short version products. Compared with imported bronzing equipment, domestic bronzing equipment has obvious advantages in terms of performance and price. The price of domestic machines is only equivalent to the price of similar foreign products in the l5~14 range, but the accuracy, stability and function of imported machines are obviously better than that of domestic ones. Machines are also more durable than domestic ones and are more suitable for the processing of fixed high-end packaging products. Therefore, the product type and lot size are the key factors that determine the selection of bronzing equipment. Whether it has high-end stamping equipment such as BOBST has become the preferred condition for customers in the industry.
Third, bronzing suitability
The so-called bronzing suitability refers to the model selection of galvanized aluminum and the matching between bronzing speed, temperature and pressure. In the case of fixed hardware such as equipment, proper control of bronzing suitability is the most important means to improve bronzing quality. The following analysis of some of the quality issues reflected in the actual operation, in order to scientifically grasp the bronzing nature.
1. This is not related to hot stamping or hot stamping, which is related to the surface characteristics of the printed parts, the nature of the electrochemical aluminum, the hot stamping temperature and pressure, and other factors.
Too much dust on the surface of the print or the surface contains additives such as release agents, bright sizing, which will hinder the adsorption of aluminum and paper. The solution: surface powder removal or solution in the printing process. Improper use of anodized aluminum directly affects the fastness of hot stamping. According to the size of the bronzing area, the characteristics of the stamped material should be considered in consideration of what type of galvanized aluminum is selected. Domestic aluminum products are mainly peacock brand series produced by Shanghai Shenyong Hot Stamping Material Co., Ltd. The imported galvanized aluminum is mainly PM and LK series from Germany Kurtz, Japan's A, K and H series and KOLON's SP series from South Korea. According to our practice and testing, the matching of the galvanized aluminum can mainly refer to the following classifications: The bronzing type of electro-aluminum on common products is type 88-l, KURZ PM; the printed materials such as cigarette packs, cosmetics, etc. (including gold and silver) ) The gold-clad anodized aluminum is available in type 88-2; the finely-printed electro-aluminums used in cigarette markings, cosmetic packaging, etc. are 88-3, 88-4, PM288, etc.; suitable for OPP or PET laminating paper and UV inks The paperboard, glossy paper and other products stamped with electro-aluminum are 88-4 type, K series, LK series, and SP series. The correct match between the hot stamping equipment and the hot stamping time and the hot stamping temperature does not affect the hot stamping fastness and sharpness of the graphic outline. Due to the different equipment and hot stamping materials, the hot pressing time and hot stamping temperature are not the same. For example, a high-speed circular press has a fast speed and the embossing line contacts. The hot stamping temperature is higher than that of a round press or a flat press. Under normal circumstances, the round stamping hot stamping temperature is between 190°C and 220°C, the rounding pressure is approximately between 130°C and 150°C, and the flattening is approximately between 100°C and 120°C. Of course, hot pressing time, hot stamping temperature and production efficiency are also largely constrained by the transferability of the electro-aluminum.
2. Anti-pulling and pulling means that after the hot stamping, the electro-aluminum will pull off the printing ink or the varnishes on the printings. The main reason is that the ink on the surface of the printed product is not dry or the post-processing of the surface of the printed product is improperly processed, which results in the ink on the surface of the printed product, the UV oil and the surface of the paper are not firmly bonded together. Solution: After the prints are dried and then hot gold. In addition, it is possible to use electro-aluminum with low electro-aluminum separation and excellent heat transfer.
3. Paste-printing and hot stamping of electro-aluminum discoloration pastes are mainly caused by poor bronzing production, looseness of the installation of anodized aluminum, or improper foiling of anodized aluminum. After the stamping, the discoloration of the electro-aluminum is mainly due to the high stamping temperature. In addition, the wrinkling of the aluminum foil is also likely to cause discoloration due to uneven color stamping, which can be solved by appropriately lowering the temperature. For the round-flattening model, fans can be installed at the foil feeding place to keep the foils from floating, avoiding the aluminum foil touching the hot stamping and scorching before the stamping.
4. The improper arrangement of the process destroys the luster of the surface of the electro-aluminum, and the outline of the graphic is confusing. In the bronzing process that requires lamination, people often worry that the gold foil will be easily wiped off and then hot stamped and then laminated. This can easily lead to:
1 The film (especially the matt film) will destroy the luster of the surface of the electrodeposited aluminum. It is not appropriate to use water-soluble glue to cover the film. Otherwise, the surface of the electrodeposited aluminum will be blackened, and the powder will easily stick to the edges of the picture and cause the phenomenon of hair crazing. gF7 China Design Online China Creative Design Portal
2 After the bronzing, the dent is caused by the pressure, and the glue is not easy to penetrate the surface of the galvanized aluminum, which can easily cause separation of the OPP from the bronzing office and affect the product quality. The correct process is to apply foil and then hot stamping, choose the matching of aluminum and OPP.
In short, there are many factors that affect the quality of bronzing. Making high-quality bronzing plates and correctly grasping bronzing suitability are the key to improving the quality of bronzing.
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