Two Problems Solved by Gravure Printing Machine in Flexo Printing Machine

People in the printing industry are relatively clear that the ink used in flexo printing machines is water-based ink, and the environmental pollution is relatively small. The packaging prints are bright and beautiful. In particular, the names of food and pharmaceutical industries must use flexo printing to print their packaging. As flexo presses have the advantages of the above two aspects, they are squeezing a share of the offset printing market, and they are also quick to compete with gravure printing with their plate making. However, the printing method used by the flexo printer determines that its ink loading is lower than that of gravure printing and screen printing. Although the quality of the large field pattern printing blocks is significantly better than that of offset printing, when printing gold and silver ink, the amount of ink is limited. Insufficient, dull printed products, can not be compared with gravure.

1 Solve the quality requirements when printing gold and silver ink

The Yixiang company in Dali, Yunnan has imported flexographic printing presses from Jacob Canada to print the cigarette tipping paper. Due to the need to print continuous single gold or double gold lines with gold ink on cigarette tipping paper, and gold lettering beside the gold thread, flexo printing has long been unable to emboss gravure printing with gold. ratio. Due to the thinness of the ink layer, the gold color of the printed gold ink is not strong and it is black. In the case of failing to meet product quality requirements, a gravure printing machine had to be added to the flexo press to print gold.

Our company has undertaken this research and manufacturing task. It is not very complicated to add a gravure printing machine to a flexo press. However, due to the domestic enterprises adding gravure printing units to imported equipment, there are several technical problems that need to be resolved: they cannot be disassembled to change the structure and relative position of the original machine, only in the unit. Space between the increase in the unit; increase the unit power can not take the original machine power, can only use AC servo motor to achieve non-synchronous rotation; the gravure printing group in addition to the original unit with the printing synchronization, it should also be attached to the automatic version function.

Because the flexo printing machine is shut down during normal operation, the host computer is not driven after the pressure is released, and only the ceramic transfer roller performs uniform ink; when the secondary pressurizing work is performed, the phase of each plate is not changed, so that the printing job can be performed. When the gravure printing machine is under pressure from the entire system, the gravure plate must be rotated slowly. The multi-color gravure printing machine is synchronized when the multi-color gravure press is pressed away. Therefore, when the printing is started again, the phase of each plate can remain unchanged. Registration. In the combination printing of a flexo printer and a gravure printer, a procedure must be set, that is, no matter how long the job is paused, the gravure group must be returned to the phase before the machine stops after the gravure is transferred to the printing. This ensures that the register state is not destroyed by dampening.

After careful planning and design, the company has installed and processed the product, which has been used by Yixiang company. The company also made the same technological transformation for Kunming Color Printing Factory, Baoji Cigarette Factory and Huzhou Tianwai Printing Company.

2 Resolved the need for matte foaming process and dark flower transfer glazing process

The practice of adding a gravure printing machine to a domestic customer's flexographic printing machine has proved that gravure printing is a supplement to flexo printing and is necessary for the printing of thicker ink layers. Therefore, it is used in flexographic printing machines produced by our company. Added gravure printing unit. In addition to the gravure printing process, the need for sanding and foaming processes and the need for glazing of dark flowers have been solved.

From the current domestic packaging printing development point of view, there are many packaging and printing on the use of the scrub and foaming process, the latest there has been UV Varnish laser dark flower transfer process, these processes require higher flexographic printing press requirements. Therefore, our company's technical staff believes that modern flexo printers should not only have flexo functions, but should become a packaging and printing processing center integrating anti-printing, gravure printing, floral transfer, sanding, foaming, and in-line bronzing functions. Among the functions discussed above, the gravure printing process not only satisfies the printing requirements of thick ink layers, but also completes several functions of sanding and foaming and dark flower transfer printing, and is an indispensable workstation for flexographic printing machines.

Scraping and foaming processes for packaging prints were first completed in the flat screen printing process. Since the UV foaming ink can produce a raised effect under the irradiation of ultraviolet rays, it will produce many strange effects, so it is used in a large amount on the packaging printing, especially in 1997-1998. However, because the screen is working under intermittent operation, its production efficiency is far from compared with flexographic and gravure printing. Then, a circular screen was introduced abroad. It can be used on screen presses on flexo presses, for example, in Stoke, the Netherlands. In addition to the need for 120,000 euros, the crew has a high manufacturing cost due to the round screen version and it is not widely used in China. The screen printing rate is unlikely to exceed 30,000 rpm and the flexo version is 1 million rpm. India's 10 million revolutions can't match, it will also reduce the efficiency and increase the cost. So we think that although the silkscreen version is successful in the process, it is limited to the experimental stage of technology, and large-scale and high-efficiency popularization in the printing industry. Farther away.

Our company has made bold explorations on the use of gravure scrubs and foaming inks. The gravure foaming operations used in Huzhou Tianwai's enterprises have been successful. The company has also used the gravure printing medium with high ink capacity in the company to achieve a moderate degree. The matte foam test has also been successful. Through experiments, we believe that micro-foaming and moderate foaming are feasible with a gravure printing machine for frosted foam printing operations. The UV intensity can be adjusted properly to match the flexographic speed. The long service life of gravure makes it match with other printing plate groups. It does not affect the printing efficiency, but also greatly simplifies the foaming process and greatly reduces the cost. Therefore, in addition to the gravure printing machine, the gravure printing group can be used normally. In addition to the printing of large amounts of ink, the replacement heater can also be used for frosting and foaming operations. This method has better applicability than the round screen technology and is worthy of promotion.

Shenzhen Weicheng Industrial Co., Ltd. has taken the lead in introducing the dark flower transfer process in China. When this process is used for glazing printing, the PET web imprinted with the laser pattern is directly coated on the non-dried UV varnish. Because the PET film is transparent and has little influence on the penetration of ultraviolet rays, After the UV drying, the PET film was peeled off, and the surface of the dried printed material was subjected to a transfer effect of laser indentation to form a dark flower, which had a landscaping package and an effective anti-counterfeiting function in a certain period of time. If the laser film unwinding and rewinding function is added before and after the gravure printing machine's gravure printing machine, an appropriate intensity of the UV drying device can be added to increase this function.

In summary, the addition of a gravure printing unit in a modern flexographic printing unit allows the product to meet different process requirements and achieve the desired quality effect of the product. Our company will launch a newly designed flexo press in mid-2004. The machine adopts a two-stage closed-loop tension control system to make the registration more accurate, and the lifting speed is quickly returned. Each workstation can be changed quickly, enabling flexo printing, gravure printing, dark flower transfer, matte, foaming, reverse printing, round Various methods for modern printing jobs such as circular hot stamping are freely implemented in new flexo presses. The whole machine adopts modular design and wireless remote control, making it a processing center for packaging printing. Gravure bears several of these functions and is one of the necessary stations in the flexo group.