Flexible packaging is one of the main branches of packaging, and it is the industry with the greatest difference in the development of flexographic printing and gravure printing. In this field, the United States uses about 70% to 80% of flexographic printing, 35% to 40% in Europe, and 5% to 8% in Asia, while the proportion in China is even lower.
In recent years, with the rapid development of China's economy and the continuous improvement of people's living standards, the requirements of product packaging in the entire market are getting higher and higher. Gravure and offset printing Solvent inks used in printing in large quantities contain chemical components such as esters, ketones and benzene. These are harmful to the human body. Only flexo printing uses a wide range of water-based inks. It is non-toxic and non-polluting, and is good for human health. Protecting the environment is beneficial. Therefore, in China, flexographic printing has become the fastest growing printing method in the printing process. From the perspective of foreign use, most of the flexographic printing machines are satellite flexo printing machines. The unit type and the cascading type account for only a small proportion, and the proportion of the three is roughly 75%, 25% and 5% respectively. Compared with the satellite flexo printing machine, the unit type flexographic printing machine has a narrower format, a long route between the units, and the tension is difficult to control, so the overprinting precision is low and the printing speed is low, so the printing of the flexible packaging is very good. Use less. Flexible packaging printing uses flexographic printing, basically using a satellite flexo press
Printing flexible packaging products with a satellite flexo press has the following advantages:
1. Low plate making cost and short cycle.
The satellite flexo printing machine uses soft polymer resin sheet, the plate making cost is about 2600 yuan per square meter, the printing durability is about 1 million times, the plate making is only a few hours, and the plate making fee has room to fall. Although the imprinting plate has a high printing durability, it takes about one week for the gravure printing plate, and the space for the plate-making fee is small. With the improvement of domestic plate manufacturing level and plate making technology, the network cable version can now reach 175 line level. The flexible packaging industry adopts satellite wide-format flexo printing machine and generally prints up to 120~133 lines, which can meet the requirements of general packaging printing.
2. Stable quality and reduce pollution.
Flexo printing uses the anilox roller to transfer ink. Since the anilox roller is both the transfer roller of the ink and the metering roller of the ink, the same short ink path as the gravure printing is realized, and the ink can be accurately supplied according to the process requirements. At present, laser-engraved ceramic anilox rolls have reached the level of 1600 lines, far higher than the highest 900 lines used daily. Due to the use of a closed doctor blade, most of the area where the aqueous ink is located in the ink chamber is sealed, and only a small portion of the contact with the anilox roll is exposed, thereby greatly reducing the amount of solvent evaporation, improving the working environment and reducing Air pollution. The closed scraper has good adaptability to printing speed. Regardless of the printing speed, the amount of ink transferred is fixed, and the closed scraper provides a powerful guarantee for precise control of ink color and ink layer thickness. Therefore, the printing quality of flexo printing is stable.
3. Zero pressure printing.
Plate and embossing rolls, plate rolls and anilox rolls use very light pressure to transfer ink, reducing vibration and wear on the machine, reducing sheet consumption, and expanding the range of print media, especially Conducive to the printing of flexible materials.
4, the ink color is consistent.
The flexographic ink layer is thinner than gravure but absolutely thicker than offset printing, which is very advantageous for large-area color blocks common in printed packaging products. Due to the use of anilox roller to transfer ink, if the printing raw materials are unchanged and the ink formulation is unchanged, the ink color between different batches of products can be consistent.
5. High speed and high efficiency.
Because the satellite flexo printing machine is light pressure printing, and the embossing roller is a large roller, the diameter of the large roller is about 1600mm in the 6-color machine, and the diameter of the large roller in the 8-color machine is about 2000mm, so even when the machine is running at high speed, it is large. The rotation speed of the drum is not very high, so the vibration and jitter of the printing frame and the large drum are small, so the satellite flexo printing machine can generally print at speeds of up to 300 m/min.
6, overprinting is accurate.
The printed substrate (film or paper) of the satellite flexo press is placed against the surface of a large metal impression cylinder and runs synchronously with the impression cylinder. The impression cylinder serves both as a printing function for transferring the ink onto the printing substrate and as a support roller for the printing substrate. Therefore, even if the film becomes soft after being heated, the driving of the film is driven by the center impression cylinder, rather than being pulled by the material itself as in the unit flexo printer. The printing color group of the satellite flexo printing machine is surrounded by the center impression cylinder, and the distance is relatively close. The film has zero tension between the color groups, so the film is easy to be overprinted, and it is difficult to face longitudinally and laterally. Run version.
7, green, environmental protection.
The satellite flexo printing machine widely uses water-based environmentally friendly inks, which are non-toxic and non-polluting, which is beneficial to human health and protect the environment.
8. The substrate is extensive.
Due to its light pressure and the fact that the substrate is wrapped on a large drum, the satellite flexo press can print on paper up to 350g/m2 or thinner to 0.018mm. Due to its stable tension, it can print both non-stretched materials and highly stretchable materials such as PE. The satellite flexo printing machine is suitable for all kinds of plastic film, vacuum aluminized film, pure aluminum foil packaging products, black and white milk film, women's sanitary napkins, daily cleaning products and medical packaging.
9. Low production cost and high economic efficiency.
Compared with gravure, flexo printing consumes about 30% less ink and saves about 40% in power. The gravure printing uses a large embossing force, so it requires a large motor power, and the oven of each color group is about 2 m, and the temperature is about 150 ° C, so a large heating power is required. The heating box between the color sets of the satellite flexo printing machine is very short, except that after the printing is completed, there is an oven of about 2 m to carry out the final drying of the film. Xi'an Aerospace Huayang Printing and Packaging Equipment Co., Ltd. began to cooperate with Italian FLAXU company in 2005 to introduce and develop a wide-format satellite flexo printing machine, which filled the domestic gap. At present, more than a dozen satellite flexo presses have been sold, which are applied to carton preprinting, tote bag printing, liquid aseptic base paper printing, and the like.
At present, our company is manufacturing a satellite flexo printing machine for plastic printing for a Shanghai user. The printing parameters of this machine are as follows:
The machine is mainly used for printing polycrystalline microporous gas permeable membranes. The membrane is characterized by its ability to penetrate air, moisture and other gases, but it cannot penetrate water under certain pressure. Therefore, the film is suitable for use in a disposable diaper, a sanitary napkin, a drying dehumidifying agent, a deoxidizing agent, a packaging material for a preservative, a film for mushroom cultivation, a composite film for agricultural use, and the like. The thinnest product of this kind of polyethylene is only 0.015mm thick, and the polyethylene is characterized by heat and easy to stretch. Like this product, printing is impossible on any other type of printing machine, and there is no printing equipment factory in China. Can make such machines, Aerospace Huayang's satellite flexo press has been successfully tested at a printing speed of 250m/min. The equipment uses many advanced technologies and has achieved the following breakthroughs:
1. The device successfully solves the wrinkle and deviation of the PE film when running on the guide roller when the tension is small and the speed is high.
2. The device successfully solves the tensile deformation of the film under tension under high temperature.
3, completed a number of slitting after high-speed printing, and received on a gas rise axis, and can be easily separated and removed from this gas rise axis. This machine is equivalent to a combination of a printing press and a slitter.
4. The machine adopts the most advanced full servo control system in China. The key parts such as the rotation of the large roller, the rotation of the plate roller, the lateral movement of the plate roller, the rotation of the wire roller, the plate roller and the feed of the wire roller are adopted. Servo motor drive. Through the PLC control, the plate cylinder and the anilox roller can quickly reach the pre-printing and pre-registration position, which greatly shortens the time for adjusting the printing pressure and printing registration, and also saves raw materials. Quick-to-plate positioning is used to achieve color registration accuracy in the first print format.
5. The micro-imprinting force adjustment is realized, and the dot reduction rate reaches 98%.
6. Due to the use of gearless transmission, there is no need to change gears when replacing printed products of different circumferences. For the gearless transmission satellite flexo press, it takes only a dozen minutes to replace the plate cylinder and the anilox roller on one unit, which greatly shortens the replacement time.
7. The imported central impression cylinder is a double-layer structure of inner and outer walls. By circulating and cooling the water in the cylinder sandwich, the temperature of the outer surface of the roller is kept constant, the thermal expansion is prevented, and the heated PE film is not softened and deformed.
8. Ink circulation system consists of two-way scraper aluminum alloy ink cartridge, ink viscosity controller and ink circulation ink supply system. It not only ensures the stability of the printing ink color, but also realizes the automatic cleaning of the wire roller on the machine, which reduces the labor intensity of the machine operator and keeps the production environment clean.
9. Rewinding adopts the first non-tape non-stop winding in China, which makes the rewinding paper tube reusable and saves costs.
With the extensive use of PE film in flexible packaging, this satellite flexo press will be welcomed by the printing and packaging industry. In addition to Xi'an Aerospace Huayang Company, which can manufacture satellite flexo printing presses, the narrow-width satellite flexo printing machine produced by Xi'an Black Cattle Co., Ltd. is an ink-jet printing machine developed for elastic materials such as napkins. Shaanxi Northwest Company and Guangdong Zhongshan Sunde Company are also developing satellite flexo presses. At present, the main reasons for the small number of satellite flexo presses for domestic applications in flexible packaging are:
1. The printed ink obtained by gravure printing is full of color, has a three-dimensional sense, and has good quality. Due to the current consumption habits, domestic soft packaging consumers pursue high printing quality, and flexible packaging printing mainly uses gravure printing machines.
2. At present, in the domestic, satellite-type flexographic printing machines are relatively expensive compared to domestic gravure printing machines and unit-type flexographic printing machines. The supporting supply chain for flexographic printing has just been formed. For example, plate and ceramic anilox roll making equipment are imported from abroad, resulting in high cost of auxiliary equipment.
3. Gravure printing is very mature in China, from printing equipment manufacturers, printing consumables, printing houses and gravure printing processes. Flexographic printing has its own craftsmanship. From pattern design to color selection, the advantages of flexo printing should be highlighted to avoid the weakness of flexo printing. At present, there is still a shortage of talents in this area in China.
4. From the perspective of quality control, gravure printing is a relatively simple process, with fewer variable factors, so quality control is simple. However, there are many factors affecting flexo printing, and the possibility of problems is also large. Because there are few domestic flexo printing machines, there are fewer people who know flexo printing machines, and fewer people have rich operational experience.
The factors that cause these causes are only temporary. With the further improvement of flexographic printing technology and related supporting chains, the above situation will change with the development of flexographic printing in China. Although the satellite flexo printing machine is still not much in the flexible packaging market, it has many advantages. According to the development trend of various factors in the industry, it can be confirmed that the number of satellite flexo printing machines in the field of flexible packaging printing There will be a substantial increase.