Flexo printing of the hottest composite hose 0

2022-08-25
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Flexible printing processing of composite hose

compared with aluminum toothpaste tube, composite hose is cheap and sanitary, and the processing process is more convenient and fast. At present, almost all toothpaste manufacturers choose composite hoses to package their toothpaste products. As a green and environment-friendly process, flexographic printing is more flexible in the printing process of composite hoses. Advantages of flexographic printing flexographic printing process has been familiar with the printing industry in China, and its advantages in printing quality, printing cost and production cycle have been fully affirmed in the hose printing industry. For example, the production of composite hoses has sufficient business sources. The printing speed and line processing capacity of flexographic printing machine can ensure that users receive the required hose products in time. In addition, flexographic printing is favored by users because of its environmental friendly characteristics. For example, the flexible version uses UV ink in hose printing, which makes the user's products completely green, safe and reliable. So that products can easily open foreign markets and create greater profit space for customers. Before printing, the feasibility analysis of the prepress process should be done well. When getting the toothpaste tube sample provided by the customer, it is necessary to carefully analyze the design focus of the designer, determine the main picture (such as the brand logo of the product, the background level of the product, etc.) and the auxiliary picture (such as the text introduction of the product, the marking of the product composition, weight, etc.), determine the color number and color sequence of the product color, and appropriately zoom two or more colors with buckle butt joint, Add tube making cursor and filling cursor on the sample according to the customer's requirements. After completing the above preparatory work, submit the revised sample to the plate making company for plate making. Then, for the defects of castings that do not affect the application quality, the corrugation rollers of each color unit are configured according to the printing plate pattern of each color (truthfully, lines, eye tones, gradients, etc.) and the color concentration of each color, and finally adjusted during proofing to restore the color to the best state. Our factory has equipped more than ten corrugated rollers for hose printing. The number of wires is 250 ~ 800 Wires/inch, and the BCM value is within the range of 3.0 ~ 12.0. When printing the field version, 250 ~ 400 lines/inch corrugation rollers are selected, 400 ~ 600 lines/inch corrugation rollers are selected when printing text and line version, and 550 ~ 800 lines/inch corrugation rollers are selected when printing eye tone and gradient version. After selecting the number of lines of the corrugation roller, the BCM value of the same line number of corrugation rollers should be compared to make the final selected configuration of the corrugation roller more reasonable and the color restoration closer to the original color. Then, the printing operation can be carried out. Our factory introduces the gelas em410 unit flexographic printing machine, which is equipped with 8 color groups of all UV printing units and 2 groups of die cutting and slitting units. The main procedures during printing production are: loading the composite sheet coil → feeding → adjusting the deviation correction device → installing each color deck wrinkle roller → installing the plate roller → adjusting the pressure between the wrinkle roller, plate roller and embossing roller → embossing → adjusting the tension → registering the plate → UV ink curing → cutting the composite sheet → winding. The process of printing hose of unit type flexographic printing machine for printing parameters is basically the same as that of coated paper, offset paper and self-adhesive paper, but the total thickness is 300 due to the thick composite sheet μ M, and the quantity is large. For most of the utilization of high molecular polymers, the inner and outer surface is PE film, so compared with general paper or self-adhesive, cardboard, etc., the control of printing tension and printing pressure is particularly critical. 1. Control of printing tension the tension system of the unit flexographic printing machine is divided into three parts: release thousands of rongxingfu bags and rich and exquisite awards! Rolling part, printing part and winding part. The gelas em410 unit flexographic printing machine of our factory is equipped with a set of swing roll unwinding tension control system, 2 sets of printing tension control system and 1 set of winding tension control system to ensure the stability of tension. The function of the tension control system of the unwinding part (also known as the pre leveling tension system) is mainly to straighten and tighten the composite sheet in advance, so as to improve the phenomena of uneven tightness, surface wrinkle, unevenness and "Ruffle edge" on both sides of the composite sheet during the manufacturing process. The tension control system of the printing part refers to the rubber roller that passes through the constant tension value in the printing process from the second leveling tension system to the completion of printing. These two groups of tension control devices are collectively referred to as the printing tension control system. Their function is to balance the printing pressure of each plate roller on the composite sheet during the printing process and the tension and resistance between the composite sheet and the paper feeding roller, UV cooling roller and other rollers, and keep the tension constant during the printing process. The printing tension should depend on the bending stiffness of the composite sheet. The higher the bending stiffness of the composite sheet, the greater the tension value should be; On the contrary, the tension of the composite sheet should be smaller. In actual production, because the surface friction coefficient of the composite sheet is relatively small, and there is "aluminum foil" as the skeleton in the middle, we should set the tension as much as possible, but also ensure that the composite sheet will not be stretched and deformed after printing. With a width of 400mm and a total thickness of 275 μ Taking the composite sheet of m as an example, the printing tension is usually set to about 320n at the front end and 360n at the rear end. The suitable point of printing tension control is based on the standard that all "chromatic points" in multicolor printing are registered and do not move back and forth. In addition, it should be noted that the speed of printing will also affect the stability of printing. Our approach is to first set the printing tension within the common range of the sheet specification used, then basically register the printing plates of various color groups, gradually increase the speed to the normal production speed, and then make appropriate fine adjustments to the printing tension according to the "moving" trend of "color registration point". The tension system of the winding part refers to the constant winding force and torsion of the back-end winding of the flexographic press during the roll to roll production. Its function is to roll the printed materials neatly and keep the rolling force of the whole roll of sheet from the inside of the roll core to the outside of the roll core consistent. When printing composite sheets, in order to make both sides of the toothpaste sheets that have been cut into small rolls smoother and the rolling force and torsion of each roll more stable, we set relatively fixed rolling force and torsion values according to the data obtained in actual operation. The set value is: coil force 60%, torque 50%, which ensures the stability of the quality of each coil of sheet during pipe making and processing. The accuracy of tension control determines the overprint quality and the overall quality of finished products when printing hose sheets with a unit flexographic press. There are many factors that determine the tension value, including the change of the production environment of each batch of composite sheets, different sheet manufacturers, different equipment for manufacturing sheets, and different composite sheet widths and printing equipment during printing. We need to master the performance and structure of various sheets and equipment, find out the range of tension value, and then adjust the best tension value during normal production. 2. Control of printing pressure. The adjustment of printing pressure is another key factor to ensure product quality. The plastic machine industry will increase by more than 12% on average every year. Before each printing, the pressure between the embossing roller, plate roller and embossing roller must be readjusted. The adjustment of printing pressure mainly includes two aspects: one is the pressure between the wrinkle roller and the plate roller; The second is the pressure between the plate roller and the impression roller. First, adjust the spacing between the three rollers. During printing (the unit is in the pressed state), the spacing between the wrinkle roller and the plate roller is basically the same as that between the plate roller and the embossing roller. Namely: 0.38mm (thickness of double-sided tape) + 1.70mm (thickness of printing plate) =2.08mm. When the old-fashioned unit is pressed, place the kraft paperboard at both ends of the roll gap, and manually adjust the spacing between the embossing roll and the plate roll, and between the plate roll and the embossing roll, taking the same resistance of pulling the kraft paperboard at both ends as the standard. At this time, the spacing is the ideal pressure value in printing, but it is slightly different from the printing pressure used in actual production, which requires operators to make fine adjustments in normal production. The gelas flexographic printing machine introduced by our factory has changed this series of cumbersome steps in design. It uses a special pressure positioning hole to position the positioning hole, which can more accurately ensure the printing pressure between the three rollers. However, the pressure value of this positioning also needs to be adjusted appropriately in actual production. Before starting production, we first carry out pressure positioning for each color deck, and relax the pressure between the plate roller and the impression roller (pay attention to the synchronization of the operating surface and the transmission surface). When the flexographic printing machine is running at a slow speed, start pressing from the printing unit of the first color group, first observe whether the ink transfer of the inking roller to the embossing roller is uniform, and then observe whether the ink transfer of the embossing roller to the plate roller is good, and then gradually increase the pressure between the plate roller and the embossing roller until pictures and texts are printed on the composite sheet (pay attention to maintain the synchronization of the operating surface and the driving surface, and ensure that the pressure is increased at both ends at the same time and evenly). Check whether the printed points on the sheet are clear, whether the pattern and text are complete, and whether there are problems such as whiteness and emptiness on the ground. In view of these problems, slightly adjust the pressure between the plate roller and the embossing roller. Flexographic printing is a light pressure printing process, and its printing pressure is far less than that of offset printing and gravure printing. When setting the flexographic printing pressure at ordinary times, it is mainly required to be small. However, in the case of hose printing, the printing pressure should be deliberately increased slightly because the substrate is a composite sheet. Taking the field version as an example, we adjust the printing pressure to vaguely see the pressure frame on the edge of the field, so as to avoid the white leakage of printed graphics and texts caused by the uneven thickness of the composite sheet per unit area. Requirements for printing equipment and consumables 1 Requirements for flexographic printing machine hose printing uses composite sheet, a high-cost material, as the substrate, so the performance requirements of flexographic printing equipment are higher than those of ordinary flexographic printing. The printing equipment must be equipped with corona treatment device, and the printing unit is equipped with a UV curing system. What's more, the equipment needs to have an accurate tension control system and the overall stability of the whole machine, and the printing quality control is convenient, The printing speed is fast, and the product variety change flexibility is high. According to the author, although many domestic equipment manufacturers such as Ziguang, Heiniu, beiren Fuji, Xinmin Taiyang, Taihang, etc. produce narrow width flexographic printing machines, hose printing is still dominated by imported equipment. 2. Requirements for ink flexographic printing belongs to relief printing. Although it has a history of nearly 100 years, the popularity of UV ink in domestic flexographic printing is only a few years. Compared with water-based inks and solvent based inks, UV inks have high viscosity and poor leveling in eye adjusted hose printing, resulting in poor ink uniformity of the wrinkle roller. During operation, it is necessary to increase the pressure between the wrinkle roller and the plate roller to show the hierarchical effect of the print. However, such operation often causes problems such as paste, reduction of printing plate printing resistance, and insufficient color saturation of printed matter. At present, water-borne UV ink has been developed abroad, which greatly improves the above situation, but the price is relatively expensive. In use, waste is often caused by improper operation. From the perspective of economic benefits, employees need to have a strong heart and pay attention to daily saving. 3. Requirements for printing materials. Printing materials account for the largest proportion of hose printing costs. But in

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