Carton and printing quality
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As we all know, the key factors affecting product quality are equipment, raw materials, personnel, and the environment. The carton packaging industry is no different. In order to build a high-quality brand, many companies spare no effort to upgrade their equipment, make technological advances, strictly control the entry of raw paper into the factory, invite talents from the world, and improve the working environment. These are commendable, but good at research, good at creation, good at doing. Those who have a heart will also benefit a lot. Here, we will briefly describe the experience of improving the quality of the carton from the perspective of ink printing.
First, to ensure the clarity of printing
Firstly, the printing plate should be made of wear-resistant, moderately elastic and high-quality materials. The thickness of the same plate should be the same. The thickness of the resin plate should be no less than 4mm, and the rubber plate should be 6-7mm. Whether it is made with negative film or by hand, the layout must be neat, the handwriting pattern, the line depth is not less than 3mm, the arrangement of the text pattern should not be overcrowded, the arc should be smooth, the thickness should be uniform, and the straight line should be straight and smooth. . The ink should be properly lightened during printing, the ink layer of the ink-coated roller should not be too thick, and the pressure of the roller should be moderate, so that the printing ink is uniform, and the surface of the box is not obviously dent. It is forbidden to increase the ink concentration and increase the pressure of the applicator roller to improve the printing effect. This will not achieve the desired purpose, but will lead to the layout of the paste ink, the printing quality is even worse, especially the text is small, the pattern is complex, the lines are delicate. Overprinting requires a high-precision layout, the disadvantage is more obvious; the speed of the printing machine can not be lower than 800 rev / min, too low, the surface of the box is uneven, and there is a bottom phenomenon. Too fast, the ink is too thick, the layout is easy to blur, and at the same time, it is necessary to prevent the paper hair, paper scraps, etc. from entering the printing machine and sticking to the printing plate. If it is found that there is paper scraping, stop it immediately, wipe it with a rag and alcohol.
Second, the printing color should be pure, no color difference in batch
The advantages and disadvantages of water-based inks are related to the purity and brightness of carton printing. Therefore, pay attention to the selection. There is no obvious difference between high-quality ink and color standard. The hand feel is fine and viscous. The concentration is suitable for adding water or alcohol solvent to dilute without precipitation and agglomeration. It is stirred with wood stick and no foam is produced. It is mixed with other inks, and the affinity is good. The phenomenon of dissolution, the color of the ink is pure, and there is no abnormal reaction. On the contrary, it cannot be used.
It is best to print in batches at the time of printing. Otherwise, the same barrel of ink will be used, and color difference will also occur. The reason is that after the original ink is diluted with water or an alcohol solvent, it is not sealed, and is exposed to the air for a long time, and the chemical components in the ink react with oxygen in the air, that is, the pigment is lowered, and the strong light also decomposes on the ink.
Third, to prevent overprinting and ghosting when printing whiteboard carton
When the coated whiteboard paper is manufactured, the coating liquid used for coating the whiteboard contains glue, and the surface of the high-grade whiteboard paper is coated with a small amount of polishing wax, so when the whiteboard is used as a paper box for printing, the printing plate and the whiteboard paper are printed. There is slippage at the moment of contact. In addition, the pressure of the printing plate is too heavy, the water-based ink is not easy to permeate, the printing of the carton ink is slow, the printing is continuous, the printing products are stacked on top of each other, and the surface of the box is scratched to form an overprinting ghost.
To solve this problem, the ink should be diluted with ethanol, do not use water, because it is not volatile, it is not suitable for drying the ink; the printing pressure is appropriately reduced, the printing speed should not be too fast, and it is not suitable for 600 rpm. Add the exhaust fan or the hot air drying box ink before the stacking of the printing machine.
Fourth, to ensure overprint accuracy
The accuracy of overprinting depends first on the precision of the equipment and whether the adjustment of the paperboard pushing paper is parallel, and the other is the layout, assembly and calibration. Let's talk about the overprint accuracy in terms of layout collage.
After the printing plate is completed, take a 0.5mm thick transparent polypropylene base, draw a vertical line at the center of its length, and then press the size of the carton to be printed, draw the long and wide high-side lines with a small stroke, and then press the sample or sample box. Production notices specify imposition. After positioning the layout position, draw a line with the water pen according to the edge of the printing plate, and then prepare the same size base in advance, over the base of the drawn line, and accurately trace all the edges (such as overprinting three colors can draw a plate base) ), and finally press the color of the overprint, and the corresponding printing plate is firmly glued to the painted position with neoprene. Then, the printing plate is attached to the roller of the printing machine by double-sided tape, and the center line of the plate is aligned with the center line of the printing plate of the printing machine. As long as the position of the imposition is accurate, other objective conditions are satisfied, and the overprinting is accurate.
Fifth, the impact of full-page printing on the strength of the carton
We know that when carton printing, corrugated cardboard is formed by the paper guide rollers and printing rollers of the printing press and transferred to the grooved part. After the paperboard is subjected to the pressure of the roller during the transfer process, the physical properties of the paper are changed to different degrees. Affects the strength of the carton. The full-page printing is particularly prominent. The strength of the carton of the same material is reduced by about 30% compared with the non-printing. Therefore, the production process should be very careful, and the following measures can be taken to alleviate:
First, properly adjust the gap between the paper guide rollers of the printing machine, so that the paperboard should pass smoothly without deformation (slightly smaller than the thickness of the cardboard 0.1-0.15mm); second, the pressure of the printing plate can be adjusted to meet the printing clarity. The handle of the box is not recessed and flat. Thirdly, the speed of the printing press (1000 rpm or more) is appropriately increased, so that the cardboard passes through the printing machine as soon as possible, thereby reducing the pressing time of the cardboard.
Sixth, the carton leaked in time to print
In the actual production of a printing machine without a computer calibration device, due to the operator's negligence, the phenomenon of missing words is difficult to avoid. Remedial measures should be taken in a timely manner after similar incidents occur. If the slotting angle is not nailed, the slotting knife can be removed, the missing layout can be subsidized to the corresponding position, and then the other nozzle plates can be removed to restart the printing, but the speed is too fast, otherwise it will cause The printing effect is not good or the layout is running. If the printed carton has been stapled, in addition to the layout of the above-mentioned method, it is also necessary to adjust the gap of each guide roller until the carton passes smoothly without deformation, and the pressure of the printing roller should be properly adjusted, and then transferred to the paper. Part of the board, determine the layout position, a single delivery when printing.
Seventh, printing notes on thin cardboard
The so-called thin cardboard, namely D, E fine corrugated cardboard, which is stamped and formed by the flat die-cutting machine after printing. Because the batch is small or the customer only does it once, and the cost of the die-cutting die is high, so the production is Switch to slotting. In actual operation, because the cardboard is too thin, the printing speed must be slowed down, but the paper feeder is not difficult to push the paper, that is, the multiple sheets of paper are simultaneously pushed into the printing machine, causing a lot of waste. To solve this problem, you can use a single machine to slot, after binding and then printing, just according to the two positive sides of the carton different editions, two times to print a complete layout of the carton.
Eighth, warped cardboard to prevent running, slotting
For the warped cardboard printing, a single sheet feeding is adopted, and the operation is performed at a low speed. At the same time, the suction amount is appropriately adjusted, and the plate slotting phase correction is performed in time according to the layout and the groove. The paperboard with severe warpage is selected, and each 3-5 positive and negative stacking weights are flattened with the weight again, or folded along the indentation line in the opposite direction of the warp.
In short, the actual situation encountered in the actual production must be treated flexibly according to objective conditions. The above is for reference only. Because of the limitations of the author's level, there are definitely some shortcomings. I would like to discuss it with my peers.