Overview of the printing process of the hottest da

2022-07-31
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Overview of the printing process of dairy packaging boxes

boxed milk is a major variety of fresh milk packaging. Almost all kinds of liquid milk with different preservation methods have boxed milk. What is the manufacturing process of this package? What are the requirements for this kind of packaging for liquid milk? This article will give a brief introduction from four aspects: packaging materials, current sanitary requirements, preservation, printing and packaging recycling. Packaging material: the packaging box of liquid milk is made of composite materials. Typical composite materials are composed of the following four materials or several of them

polyethylene (hereinafter referred to as PE) - sealing layer, which can block moisture and bacteria; Paperboard - used to improve the hardness and strength of the box, and has the function of avoiding light; Aluminum foil - excellent performance of oxygen isolation and light protection; EVOH high-efficiency barrier layer - a substitute for aluminum foil, is also used to block oxygen and avoid light

according to the different preservation period of fresh milk, the box making materials are also different. The structure of the short-term fresh milk packaging box that needs to be refrigerated is relatively simple, and pe/paperboard/pe composite materials are usually used; The aseptic filling milk packaging box used for long-term storage in normal temperature environment is made of pe/paperboard/bonding layer/aluminum foil/bonding layer/pe, or pe/paperboard/evoh/bonding layer/pe composite material. Figure 1 shows the material structure of a fresh milk packaging box

printing forming 1 Advantages of flexographic printing the printing methods of dairy packaging boxes include offset printing, gravure printing and flexographic printing. In the past, offset printing accounted for a high proportion. In recent years, with the progress of flexo printing technology and the improvement of flexo printing quality, the proportion of flexo printing in packaging has been increasing. Compared with gravure printing and offset printing, flexo printing has many characteristics. 1) Short time for product replacement: for example, for a BHS unit flexographic press, you must provide a material type printing plate for less than 2 minutes, the preparation time for changing the printing color on a unit is 8-10 minutes, and the time for replacing a wrinkle roller (or sleeve) is less than 3 minutes. 2) Strong drying ability: the drying ability is very important for water-based ink, especially for field printing. The drying device of each unit can be controlled independently by frequency conversion. The heating medium can be gas, hot oil or electric heating. Flexo printing machines are generally equipped with UV curing devices to facilitate the application of UV ink. 3) Gearless transmission: gearless transmission technology has many advantages. First, the diameter of the plate roll can be changed arbitrarily and continuously without changing the gears as in the past; Second, you can use the same diameter of the plate roller to print different specifications; Third, it is convenient to compensate the paperboard or printing plate with different thickness. 4) Easy to monitor: the control and display system of advanced flexo printing machines, such as BHS flexo printing machine, can detect and display various data required for production, and can store the production process data of live parts, which is easy to reuse. The system can monitor the machine in real time, display the fault point, and the operator can handle the fault according to the instructions. For complex faults, remote diagnosis can also be implemented by the manufacturer through the network. 5) Convenient paper change: for example, the paper change of BHS flexo press adopts the docking method, which does not need to be overlapped, which can reduce the waste of paper; Because the paper is received at zero speed without stopping the machine, the operation is simple and the efficiency is high. And before stopping the machine, all the corrugated rollers will be automatically disengaged to avoid damaging the roller parts of each version. 6) Easy on-line processing: flexo printing machines are generally multi unit, and the last unit can be used for (water-based or UV) glazing. When on-line die-cutting and indentation are required, either round die-cutting or flat die-cutting can be selected. In order to facilitate collection after die cutting, the transfer arrangement can be changed, for example, from two rows to four rows during die cutting, so as to reduce the speed of collection. 2. characteristics of dairy packaging box printing and post press processing there are some differences in the printing process of packaging for different purposes. The packing box used for short-term preservation is made of pe/cardboard/pe, and UV printing is directly carried out on the PE material during printing; For packaging boxes with long shelf life, due to the need for high-temperature treatment, they are printed on the cardboard first, and then PE is compounded on the cardboard by extrusion compounding method. There are two ways to form the packaging box. One is to configure an online die cutting and indentation unit behind the printing machine to complete printing, indentation and die cutting at the same time, and then send it to the box pasting machine for processing; The other is roll to roll printing, which is used by the filling line after being cut into narrow rolls. Shanghai International Paper Co., Ltd. is a large-scale enterprise producing fresh milk packaging boxes. They use two BHS 9-color flexographic printing machines, which are online produced with rotary die cutting machine and indentation unit. They use UV ink to print the classic introduction of mold size and plastic shrinkage! The printing width of pe/paperboard/pe packing box is 820mm, and the production speed is 250m/min

recycling of packaging boxes recycling and reuse of packaging is related to the living environment of human beings. Therefore, how to recycle and reuse dairy packaging boxes must be considered while producing and consuming dairy packaging boxes. About 75% of the ingredients of dairy packaging boxes are fiber. Therefore, in developed countries, 98% of dairy or beverage boxes are recycled by paper mills for remanufacturing pulp. The recycled pulp can be used to produce a variety of paper products, such as paper bags, cartons, egg packaging molds, and even product sample paper. For the residues of papermaking (PE or aluminum-plastic mixture), further treatment is required. 1. Because the mixed composite materials contain all carbon materials, carbon fibers are processed in incinerators, industrial boilers and cement kilns to generate energy; Or used to make barrel containers, outdoor furniture and roof materials. The burying method is no longer an option. In China, the die-cutting waste in the printing factory has been recycled by special personnel, but the problem of packaging recycling after consumption remains to be solved

reprinted from: Printing Technology

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