The complete process and quality control method of bronzing
With the improvement of the national economy and the development of the printing and packaging industry, people require the packaging of products to be high-grade, exquisite, environmentally friendly and individualized. In the post-press processing of packaging products, anodized hot stamping process is favored by people because of its unique surface finishing effect, and it is used in high-grade packaging such as banknotes, cigarette labels, medicines, cosmetics and so on.
Anodized aluminum hot stamping refers to hot stamping, hot silver and other hot stamping materials hot stamping process, in order to facilitate the discussion, the following bronzing general called anodized aluminum hot stamping. Bronzing mainly has two functions, one is surface decoration, improve the added value of the product. Love festival, resplendent for our national tradition, bronzing and pressure convex technology combined to show its luxury; Two is to give the product high anti-counterfeiting performance, the use of holographic positioning hot stamping trademark logo, anti-counterfeiting, brand protection.
At the same time, bronzing is very able to show the personalized product packaging and safety and environmental protection. Therefore, many high-grade packaging have adopted the bronzing process, so how to improve the quality of bronzing? This article makes a discussion from the following aspects.
One, bronzing plate
High quality bronzing plate is the primary factor to ensure the quality of bronzing. At present, the production of bronzing plate mainly adopts photographic etching process and electronic engraving technology, materials commonly used copper or zinc. The copper plate material is fine, the surface finish, heat transfer effect is better than zinc, the use of high-quality copper plate can improve the glossiness and outline definition of bronzing text. The traditional photographic etching technology to make bronzing plate process is simple, low cost, mainly used for text, thick lines, general images; For fine, text and text thickness is not equal bronzing plate need to use two times deep or the use of electric engraving technology.
Electric engraving bronzing plate can show rich and delicate level changes, greatly expanding the performance ability of packaging, the process is conducive to environmental protection, but the investment of electric engraving equipment is large, the current depth of engraving is not ideal, easy to cause bronzing "paste version".
Holographic anti-counterfeiting bronzing plate production technology requirements are high, mainly in Taiwan or foreign production, plate making cycle is longer, only used for fixed, large batch products packaging. At present, domestic Shanxi Yuncheng, Beijing and Shanghai have a few units can be made.
Two, bronzing equipment
"If a worker wants to do a good job, he must sharpen his tools first." The selection of bronzing equipment is the key factor to determine the quality of bronzing. Sheet-fed bronzing machine has three types: flat stamping machine, circular stamping machine and circular stamping machine. At present, the most widely used type is flat stamping machine, which mainly includes: TYM series die-cutting and gilding dual-use machine of Shanghai Yahua Printing Machinery Co., Ltd., TYML020 type automatic gilding die-cutting machine of Tangshan Yuyin Group Co., Ltd., MK series automatic gilding die-cutting machine of Tianjin Youheng Machinery Industry Co., Ltd., the highest gilding speed is 5000 pieces/hour.
Steuer FOLLJET FBRL04 bronzing machine is the representative of circular stamping machine. Using the design concept of offset press, the highest hot stamping speed can reach 10,000 sheets/hour, which is the fastest equipment for single sheet bronzing in the world at present.
Rotary stamping, circular stamping, flat stamping three kinds of stamping machines have their own advantages and disadvantages: Press circle round, round flat hot stamping is the line pressure, total pressure is small, with a relatively small pressure easy to complete large area field bronzing, smooth movement, round and round pressure production efficiency is higher, especially suitable for mass live parts stamping, but due to the copper plate arc surface processing is difficult, production cost is higher, the heating roller is better than flat heating difficult. Flat pressing flexible and convenient operation, more suitable for short version of the product.
Compared with imported bronzing equipment, domestic bronzing equipment has obvious advantages in performance and price. The price of domestic bronzing equipment is only equivalent to the price of similar foreign products. However, the overprinting accuracy, stability and function of imported machines are obviously better than that of domestic machines. Therefore, the product type and batch is the key to determine the selection of bronzing equipment. Whether to have BOBST and other high-grade bronzing die-cutting equipment in the industry has become the first choice of customers.
Three, bronzing suitability
The so-called bronzing adaptability refers to the choice of anodized model and the matching between bronzing speed, temperature, pressure and other factors. The most important way to improve the quality of bronzing is to correctly grasp the bronzing adaptability under the condition of fixed equipment and other hardware. The following is an analysis of some quality problems reflected in the actual operation in order to grasp the bronzing suitability scientifically.
1 hot stamping or hot stamping is not real, which is related to the printing surface characteristics, the nature of anodized aluminum, hot stamping temperature and pressure and other factors.
(1) too much powder spraying on the surface or surface containing adhesive removal agent, light slurry and other additives, which will prevent the adsorption of anodized paper.
Solution: surface powder treatment or in the printing process to solve.
Improper selection of aluminum oxide directly affects the bronzing fastness.
According to the size of the bronzing area, the characteristics of the hot stamping material should be considered comprehensively to choose what type of anodized aluminum. Domestic aluminum oxide is mainly Peacock brand series produced by Shanghai Shenyong Bronzing Materials Co., Ltd., imported aluminum oxide is mainly German Kurz (PM and LK series), Japan's A, K, H series, South Korea's Kolon SP series.
According to our practice and testing, the selection of anodized aluminum can refer to the following categories:
● Ordinary products on the bronzing (general ink) anodized aluminum 88-L type, Kurz PM type;
● cigarette package, cosmetics and other thick ink printed matter (including gold, silver) bronzing aluminum anodized 88-2 type;
● cigarette label, cosmetics packaging and other fine handwriting hot stamping aluminum oxide 88-3, 88-4 type, PM288, etc.;
● Suitable for OPP or PET coated paper and UV ink cardboard, glazing paper and other products of hot stamping anodized aluminum 88-4, K series, LK series, and SP series.
(3) not correctly grasp the bronzing equipment and the match between hot stamping time and hot stamping temperature, affecting the hot stamping fastness and the definition of graphic outline.
Because of the equipment, hot stamping material is different, hot stamping time, hot stamping temperature are not the same. For example, high speed rotary press fast, embossing line contact, hot stamping temperature is higher than the round or flat. Under normal circumstances, circular stamping temperature at 190℃ ~ 220℃, circular flattening at about 130℃ ~ 150℃, flattening at about 100℃ ~ 120℃. Of course, hot stamping time, hot stamping temperature and production efficiency are also largely restricted by the transfer performance of aluminum oxide.
2 back pull back refers to the hot stamping after the anodized printing ink or printing parts on the oil to pull away. This is mainly due to the surface of the printing ink is not dry or printing surface UV post-processing treatment, resulting in printing surface ink, UV oil and paper surface combination is not strong.
Solution: to be printed dry and then bronzing. In addition can choose the aluminum oxide separation force is low, good heat transfer of aluminum oxide.
3 paste version and hot stamping after anodized color paste is mainly due to the bronzing plate production is not good, anodized installation of slack or anodized foil is not correct. After hot stamping anodized discoloration is mainly caused by high hot stamping temperature. In addition, anodized wrinkling is also easy to cause hot stamping overlap color uneven and discoloration, can be properly reduced temperature solution. For the circular flattening model, a fan can be installed at the foil feeding place to keep the foil fluttering and avoid the anodized aluminum touching the bronzing plate before hot stamping and scorching.
4 improper process arrangement, the destruction of anodized surface luster, image and text contour faint. The need for film processing of bronzing, people often worry that gold foil is easy to wipe off and hot stamping and then film, which is easy to cause:
The film (especially the matte film) will destroy the luster of the anodized surface, it is not suitable to use water-soluble glue laminating, otherwise it will cause the anodized surface to blacken, and it is easy to cause the gold powder sticking to the edge of the text and text to cause the phenomenon of deficiency.
② After bronzing, it is depressed due to the effect of pressure, and the glue is not easy to penetrate the anodized aluminum surface, which is easy to cause the separation of OPP and paper in the bronzing place and affect the quality of the product. The correct process is should be first covered with film and then bronzing, choose and OPP matching aluminum oxide.
In short, there are many factors that affect the quality of bronzing. To make high-quality bronzing plates, the correct grasp of bronzing suitability is the key to improve the quality of bronzing