1 What is sweeping technology
The so-called gold sweeping is the process of realizing the metallic luster effect by attaching a special metal powder to a specified part of a commodity package or a label print through a special process. This kind of technology can get realistic metal texture and better luster. At the same time, the pattern is fine and overprinting is accurate.
2 Application of gold sweeping technology
The gold sweeping technology is widely used in the packaging of cigarettes, wine, medicines, cosmetics and high-end foods, as well as the printing of greeting cards, invitations, calendars and other products, which can greatly increase the added value of goods. In the 1990s, China's gold-sweeping technology has achieved certain development. Some areas with advanced packaging and printing (such as Guangdong) have also introduced several gold-sweeping machines, which are mainly used for the production of cigarette packets and drug packets. As China's packaging requirements increase, the gold-swamping technology will have greater development.
3 sweep gold process principle
The process of sweeping gold is actually very simple. Put the sheets of gold sweeps on a monochrome or two-color offset press. Use a special PS board to print a layer of viscous glue on the parts where you need to sweep the gold, and then press the paper into the sweeper. Machine, sweeping the powder and polishing, gilt, etc. can be completed.
At present, the Jazz brand automatic gold sweeper produced in Germany is mainly composed of 5 parts: paper feeding mechanism, coating mechanism, polishing mechanism, cleaning mechanism, and delivery mechanism. The prints can be processed from thin paper to cardboard, from four to full sheets, and the speed can reach 8000 sheets/hour. The gold sweeper usually needs a flat sheet single (double) offset press (to remove the delivery device) to connect with the sweeper. Firstly, the special PS version of the sweeper machine is well installed and adjusted on the offset printing press. The PS version is used to print a thin and uniform primer on the printed part of the print, and then the print is passed through the gold sweeper. The paper transfer device is sent to the suction rubber conveyor belt of the sweeper, and the gold powder is evenly applied to the surface of the print sheet by the coating mechanism. When the side of the applicator roll, on which the gold powder is adsorbed, goes to the top of the sheet, this part is switched from inhalation to blowing and the powder is evenly sprayed over the entire surface of the sheet. The four polishers of the polishing mechanism are rubbed and polished with the gold powder on the print sheet so that the gold powder printed with the bottom glue part on the print sheet firmly sticks. At the same time, the gold sweeper also uses four special sheet metal belts, which perform opposite reciprocal movements between each other to improve the metallic luster and adhesive fastness. The latter two are equipped with a powerful suction pipe to remove excess powder. The high-vacuum adsorption multi-channel cleaning cycle system of the cleaning organization plus the preceding suction pipe can quickly clear the excess gold powder on the printed sheets. The excess gold powder can be recycled without causing environmental pollution or waste. In the end, the paper collection organization completes the paper collection and finishing work.
Of course, if the printing plant has multi-color printing presses and UV drying devices, on-line gold scanning can be carried out. That is, printing sheets are printed on the first few colors of the printing press and fully dried by the UV drying device on the last color set. The primer is printed and then transferred to the gold sweeper via the connecting device.
4 The characteristics of sweep gold technology
The gold-sweeping technology has advantages in many aspects compared with other kinds of gold-imitation processing technology, and of course there are also deficiencies.
1) Compared with printing gold
At present, gold can be offset, gravure, flexo, and screen printing, especially offset and gravure, both of which are faster. The offset printing ink is thin and the metallic luster is not very good. The gravure printing ink layer is thicker and the gloss is better than the offset printing. However, the metal texture is not strong enough when printing on a large area. It is easy to deform when printing small prints and thin lines and the quality is not good enough to control.
2) Compared with bronzing
Hot stamping as a traditional imitation gold processing technology, metal luster and metal texture are very strong, is an indispensable processing technology for some high-end packaging, in this regard it is better than the gold scan. Although the quality of the gilding effect is good, but most of it needs to be affixed to the family and the genus. Persimmon ç° ç° åˆ‚ 刂 刂 å–½               æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž æ’¸îƒè –å—îž
3) Compared with frosted printing
Although the matte printing has a good metal texture and luster, the production efficiency is low, and the discarded packaging is not easy to recycle, which is not conducive to environmental protection.
4) The advantages of sweeping technology
The technology of sweeping gold is simple, fast, and low in cost. No matter the thickness or size of the image, the area can get good results.
After sweeping the gold, the metal sand and light diffuse reflection effects of the product are better, and the metal texture is more real, giving a visually distinct three-dimensional appearance, which is different from the printing of gold and bronzing.
The color of the sweeper is colorful, in addition to the most commonly used gold, silver, bronze, green, graphite, tan, lemon yellow, peacock blue, and the widely used imitation diamond powder recently used in Europe and North America. And laser gold powder. These gold powders have different particle sizes and can show a variety of unique effects.
 Anti-counterfeiting effect: Because the gold imitation effect obtained by gold sweeping is different from that of gold printing, hot stamping and frosted printing, it is unique, difficult to imitate, and has a certain anti-counterfeiting function.
5) The disadvantages of sweeping money
Although sweeping technology has obvious advantages, it is not perfect.
The most important feature of sweeping gold is the formation of imitation gold effects in specific areas. However, it is difficult to achieve the best metallic luster and texture in a single gold sweeping process. It is not as good as gold foiling in some respects.
 It is not as convenient as printing gold on the printed sheets that require a large area of ​​imitation gold, and there is no advantage in effect. Therefore, gold sweeping is only a mid-range gold-imitation effect processing technology. It has certain limitations, which restricts its rapid development to some extent.
The requirements of the sweeper on the environment are very high. The temperature should be controlled at 22 to 25°C and the humidity should be controlled at 50 to 55%. Otherwise, quality problems are likely to occur.
The common faults in sweeping gold are dirt and powder. The main causes are as follows: (1) The humidity of the gold sweeping workshop is too high or the moisture content of the paper is too high, which can cause the gilt-gold ribbon to get wet and dirty; 2 the imprinting of the printed matter is not dried out, resulting in the adhesion of gold powder to the parts that do not need to sweep gold; 3 The viscosity of the primer at the site where the gold is to be scanned is insufficient or the glue is insufficient to cause powder fall-off.
5 Concluding remarks
From the above analysis, although there are still certain shortcomings in sweep gold technology, its advantages are still very obvious, especially in terms of security, metal texture, and advertising effects. At the same time, the cost of sweeps is relatively low, and printers can obtain higher profits. Although there are not many manufacturers currently using sweepers in China, with the continuous maturation of gold powder processing technology and gold sweeping technology, as well as the perfect combination of gold sweeping, bronzing and silk screen printing, it will be in the domestic packaging and printing industry, especially in the It plays a unique role in cigarette packs, wine bags, and high-end medicines and food packaging.