Post-printing technology
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
With the development of the packaging and printing market, the packaging process is becoming more mature and diversified. In order to pursue the grade of commodity packaging and increase the added value of goods, a new technology of imitation gold effect on the packaging of goods - the sweeping gold technology was born.
First, what is the gold sweeping technology?
Sweeping gold is a special post-press process in the production of fine prints. It is a special metal powder attached to a designated part of a product packaging or label print to achieve a gold-like glittering effect. This technology gives a realistic metal texture and a good gloss, while the pattern is fine and the overprint is accurate. After sweeping gold, the product has better metal grain and light diffuse reflection effect, and the metal texture is more realistic, giving a visually obvious three-dimensional feeling, different from gold and bronzing.
Second, the sweeping process
The process of sweeping gold is actually very simple. Put the sheet that needs to be cleaned on a single-color or two-color offset press, apply a layer of adhesive glue to the part that needs to sweep the gold with a special PS plate, and then print the sheet through the paper feeding device to enter the sweeping gold. Machine, sweep the gold powder and polish, sheet metal, etc. to complete.
The gold sweeping process is completed by a sweeping machine. The sweeping machine is mainly composed of a paper feeding mechanism, a coating mechanism, a polishing mechanism, a cleaning mechanism, and a delivery mechanism. The process flow is as follows: the sweeping machine generally needs a single single (double) color offset printing machine (to remove the delivery device) to connect with the sweeping machine when sweeping gold. The PS version dedicated to the gold sweeper is made by using the color separation film of the printed product, and is installed on the offset printing machine, and the registration work can be completed by adjusting the rules of the offset printing machine. Use the PS version to print a thin and even layer of primer on the printed matter that needs to be coated with gold powder (commonly known as “sweeping gold”). The printed matter printed with the primer is sent to the rubber conveyor belt with the suction passage through the sweeping machine paper conveying device, and the coating device consisting of the gold powder filler, the applicator with the ink fountain roller, and the coating roller start up. The coating roller rotates, and when the side of the coating roller that adsorbs the gold powder is turned over the paper, the portion is switched from inhaling to blowing, and the gold powder is evenly sprayed on the surface of the paper. Four special polishers are used to rub and polish the gold powder on the paper, and the gold powder printed on the paper with the primer is stuck on the paper.
The sweeping machine uses four special sheet metal belts to reverse the reciprocating motion between the two to improve the metallic luster and the bonding fastness. The latter two have a strong suction pipe, plus a high vacuum adsorption of the cleaning mechanism. The multi-way cleaning cycle system can clean the excess gold powder on the printed sheet quickly and quickly. The excess gold powder can be recycled without causing environmental pollution or waste. Finally, the delivery and finishing work is completed by the delivery mechanism.
If the printing manufacturer has a multi-color printing machine and a UV drying device, it can perform online sweeping, that is, the printing sheets are printed in the first few color groups of the multi-color printing machine and fully dried by the UV device, and then finally A color set is printed with a sticky base ink, and then enters the sweeping machine through the connecting device for gold sweeping. In the above situation, when the gold is not needed, the gold sweeping equipment can be separated from the printing machine within a few minutes, so that the printing press can perform ordinary printing.
Third, the characteristics of the sweeping process
When sweeping gold is compared with the processing technology of imitation gold effect in other fine printing, it has its own unique advantages. Gold and hot stamping, as a widely used process, have many advantages, but there are also some shortcomings. For example, at present, gold can be offset, gravure, flexo and silk screen, especially offset and gravure, both of which are faster. The offset ink layer is thin and the metallic luster is not so good; although the gravure ink layer is thicker and the gloss is better than the offset printing, the metal texture is not strong enough when printing in a large area, and the deformation is relatively serious when printing small characters and thin lines; A traditional process, the metal is also very strong, but the energy consumption is higher, the efficiency is relatively low, the registration is somewhat difficult, the small graphics and large area bronzing, the quality is not easy to control; the matte printing has a good metal texture And luster, but the production efficiency is low, and the discarded packaging is not easy to recycle, which is not conducive to environmental protection. The sweeping gold technology has a simple operation process and a high production speed (up to 7,500 sheets/hour), and the cost is low. No matter the thickness or size of the image, you can get better results. Gold powder also has a variety of colors, such as gold, silver, red gold, copper, green, graphite, tan, lemon yellow, peacock blue, etc., can be described as everything, and has different granularity, can present a rich color . At present, a kind of gold powder with imitation diamond effect has been popularized in North America and Europe. The gold powder has 4 kinds of particle sizes and 10 colors, which can make the decoration graphic like a diamond collection under the illumination of light, reflecting the multicolored light. Unique effect. Due to the use of metal particles as raw materials, gold-swept products have a metallic grit and light diffuse reflection effect, which is closer to the original texture of real metal. The gold-swept products visually give a distinct three-dimensional sense, feel smooth and feel unique, and the surface finish is unique, unlike gold and bronzing. The gold-sweeping process has a unique effect on the surface of the printed matter, and it also plays a certain anti-counterfeiting function because it is difficult to imitate. Based on this, the gold-sweeping process has attracted the favor of packaging users such as wine, cosmetics and medicine.
Although sweeping technology has a very obvious advantage, it is not perfect. The main feature of sweeping gold is the effect of forming a gold-like effect on a specific part. However, it is difficult to achieve the best metallic luster and texture by a single sweeping process. It is not as good as bronzing in some respects. On a sheet that requires a large area of imitation gold, it is not as convenient as printing gold, and there is no advantage in effect. Therefore, sweeping gold is only a mid-range imitation gold effect processing technology, which has certain limitations, which limits its rapid development to a certain extent. The environment of the gold sweeper is very high. The temperature should be controlled at 22~25°C, and the humidity should be controlled at 50~55%. Otherwise, quality problems are easy to occur.
Fourth, common faults in the sweeping process
The most common fault in the sweeping process is sticky (ie, the blank part of the paper is stuck with gold powder). The main reasons for the dirty gold are:
1 The humidity in the workshop is too high, causing the sheet metal to get wet and sticking to the gold powder, so that the sheet metal is not clean;
2 The humidity of the printed sheet exceeds the standard, which causes the sheet metal to be unclean;
3 The ink on the printed sheet before the gold sweep is not dry, and the ink that is not dry is inherently sticky, and the non-sweeping portion is also stuck with gold powder;
4 The gold powder on the gold-plated part of the printed sheet is not firmly adhered, resulting in powder drop.
The corresponding solution is:
1 Adjust the humidity of the workshop to keep the humidity of the workshop within a reasonable range;
2 control the humidity of the printed sheet, and dry the printed sheet before sweeping the gold;
3 using ink with suitable drying performance or after the ink on the sheet is fully dried before sweeping;
The reason why the gold powder is not firmly adhered may be caused by too much alkalinity of the dampening solution or too much pressure of the polisher, and the corresponding measures can be taken.
Fifth, the application of sweeping gold technology
In foreign countries, the application of gold sweeping is very common. Many printing factories adopt multi-shift work system and make full use of the new gold sweeper, which has achieved significant economic benefits. Today, the only company in the world that produces fully automatic sweeping machines is the German company Dreissig. Its latest model 2500 sweeping machine has passed the rigorous inspection by the official agency and obtained the CE safety certification. At present, it has been widely used all over the world. It solves the problem of dust pollution and raises the speed of sweeping gold to nearly 8,000 sheets/hour, even close to 9000 sheets/hour. The sweeping process is widely used in the packaging of cigarettes, wine, cosmetics, chocolate, etc., as well as the printing of greeting cards and invitations, so that the value of the goods can be further improved. The equipment has now been introduced to China by Jiuheng Printing and Packaging Equipment Co., a subsidiary of the Sanjiu Group, and will push China's packaging and printing to a new level. Domestic users are mainly concentrated in cigarette labels, followed by medicine boxes and food packaging, and several gold sweepers have been introduced in the South China and East China regions, which account for a considerable proportion of China's packaging and printing processing. Relative to foreign countries, the domestic application of gold sweeping manufacturers can be described as rare, this may be because the domestic generally appreciate the sparkling bronzing effect, the gold sweep closer to the color of the metal itself is not very concerned. In addition, some printing companies in China are not very familiar with the technology of sweeping gold. Many domestic manufacturers are still not fully aware of the fierce competition in the market. The pressure has not been so great that they can use the gold-sweeping process to improve their packaging. Therefore, even if the manufacturers know it, Will not consider investing in this printing fee. At the same time, the shortcomings of the sweeping gold technology itself are also an important reason. At present, in China, the competition in the gold sweeping market is not intense, and the price pressure is not large. In addition, sweeping products have unique anti-counterfeiting features and advertising effects, allowing customers to accept a range of price differences; plus the cost of sweeping gold is relatively low. Therefore, printers can obtain higher profits.
The development of modern science and technology and the development of polymer materials industry and processing equipment have driven the development of post-press processing technology. Today's post-press processing is developing in the direction of intelligence, automation and diversification. As part of post-press processing, gold-sweeping technology is in the process of development. It is believed that as China's packaging design is aligned with international standards, China's packaging design level is constantly improving and its individuality is more prominent. The sweeping gold process, with its unique superior performance, will be promoted as China's packaging level improves.