The greening of the hottest paper packaging II

2022-07-27
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Green paper packaging (II)

3.2 flexo printing technology

the development and application of new flexible plate and thin plate technology, sleeve printing plate and computer direct plate making technology, environmental friendly UV ink, high-speed ceramic roller laser engraving technology, closed doctor blade system, gearless transmission technology, non-stop roll changing device and automatic control technology have promoted the rapid development of flexo printing

(1) the improvement of the quality of photosensitive resin plates and the emergence of thin plate technology based on thin plate printing and CDI technology have laid a good foundation for improving the quality of printing plates. The application of CTP technology and the emergence of digital flexo plate making technology (CDI) can effectively overcome the phenomenon of point expansion, ensure the quality of printing products, shorten the production cycle and reduce the cost consumption

the digital thin sleeve printing plate has good stability, can effectively control the expansion of control points, reduce photosensitive polymers, and improve image quality and registration accuracy. It can not only improve the printing quality of paper packaging, but also make the flexo printing quality reach the quality level of offset printing and gravure printing. It can also reduce the printing pressure, reduce the times of plate cleaning, extend the service life of the printing plate (the time limit can be increased by%), further shorten the preparation time for machine adjustment, reduce the times of downtime and it during downtime (10- 20%)

the CDI system jointly developed by DuPont and DuPont Saili can directly transfer the digital information to the laser photosensitive printing plate. The CDI plate making machine spark XT developed by Esko graphics is mainly aimed at the packaging and printing market, especially small and medium-sized label and folding carton flexographic printing enterprises. With the continuous progress of technology and the introduction of various systems, the cost of flexographic digital imaging plate making system is also declining, and its proportion in the printing of paper products such as cartons, paper bags, multi-layer packaging bags is becoming higher and higher

(2) sleeve type high-speed ceramic roller

laser engraving ceramic roller is to spray alloy on the surface of the treated base roller as the base layer, then spray ceramic powder with plasma at high temperature, after diamond grinding and polishing, accurately carve sharp and steep holes with high-energy laser beam, and finally finish polishing. The number of lines and the amount of ink are the most important parameters for making laser engraving ceramic patterns. The roller with high number of lines can form a thinner and more uniform ink layer, which can meet the requirements of printing products with rich layers, especially the needs of its highlight part. It can reduce the expansion of points during printing and maintain a constant and uniform ink transfer

sleeve type high-speed ceramic urn roller. It adopts ultra-high energy laser beam engraving technology and sleeve type roller structure composed of mandrel, air support roller and sleeve, which not only ensures the quality of high-precision roller, but also realizes the rapid replacement of plate roller. The roller adopts sleeve type structure and direct drive technology (that is, the rotation of roller is directly driven by plate roller), The problem that the repeat length of flexographic printing products is limited by the gear pitch is solved. Therefore, when replacing printing products with different perimeter, it is not necessary to replace the mandrel and gear of the plate cylinder and the embossing roller, which greatly shortens the time spent in replacing the plate cylinder and the embossing roller

the number of carbon dioxide laser engraving ceramic roller lines can reach 1000lpi. The price rise of various raw materials using special ceramics since September 2016 is causing a fatal impact on the ceramic layer or super hard ceramic layer in the export industries such as home appliances, furniture, textiles and clothing, which can improve the service life of the ceramic roller and reduce the use cost

the ceramic roller processed by YAG laser engraving technology has smooth hole wall, neat wall, high finish, accurate ink transfer and small scraper loss. It can not only prolong the service life of the ceramic roller, but also extend the service life of the printing plate. The high-power and high-precision YAG laser engraving machine can engrave 16001pi corrugated rollers

(3) closed double scraper cavity inking system

although the two roll, forward scraper and reverse scraper structures can realize quantitative ink supply, the ink is often exposed to the atmosphere directly in a large area, which makes the solvent of the solvent ink volatilize into the surrounding air, causing ink characteristic changes and environmental pollution problems: if the water-based ink is used, bubbles will be generated, which will affect the printing quality

the closed double scraper cavity inking system consists of ceramic rollers, two scrapers, sealing strips, ink storage containers, ink pumps, ink hoses and other components. In the fully enclosed system, the scraper, seal strip, gasket and pressing plate are all installed on a cavity type support. They are pushed to the ceramic roller mechanically (or pneumatically or hydraulically) and a certain pressure is applied. Then the ink delivery pipe and return pipe are connected to the ink pump and the ink storage container respectively to realize the quantitative ink supply. The reverse scraper structure is adopted, which is suitable for high-speed operation and reduces the volatilization of the solvent in the solvent based ink and environmental pollution. The system can also be quickly connected with the automatic cleaning system to facilitate rapid cleaning and reduce ink change time and downtime

(4) environmental friendly flexographic ink

today, people pay more and more attention to environmental protection. Water-based ink and UV ink meet the market demand and promote the application of flexographic printing in the field of packaging printing. It can not only be used for printing various coated paper, offset paper and whiteboard, but also can be printed on printing carriers such as gold silver card, synthetic paper, self-adhesive paper and corrugated box

water based (or water-based) inks take water as the main solvent. They are non-toxic, pollution-free and have no residual odor. They completely eliminate the harm of some toxic substances in solvent inks to human body and the pollution to packaged goods, effectively reduce air pollution, improve environmental quality and printing environment, and are especially suitable for drugs, food, beverages, tea The packaging and printing of tobacco, alcohol and daily necessities in contact with human body, which have strict requirements on sanitary conditions

under UV irradiation, the photoinitiator in the UV ink is stimulated to decompose into free radicals, which make the cross-linking reaction take place rapidly and make the colloidal components become solid instantly. UV inks are mainly composed of pigments, photosensitive resins, active diluents, photoinitiators and additives. They do not contain volatile organic solvents, which can greatly reduce VOC emissions, and consume less energy. The samples should be cut from the test pieces with uniform thickness. They cover a small area, are easy to dry, and have high production efficiency. As the UV ink has no volatilization problem of water or solvent, the whole experimental process of dot is controlled by computer program, and the transfer and reduction are good, and "this is also important for subsequent recovery, and the color is more bright, which plays a great role in improving the quality of flexo printing. Although the drying cost of UV ink is significantly higher than that of water-based ink, UV ink has good UV curing efficiency and ink layer properties, which can well protect the surface of prints

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