1. The problems caused by low grammage paper.
When low grammage paper is used as the surface paper of corrugated cardboard, it will cause the surface of the corrugated cardboard to show the corrugation marks. It is easy to cause the corrugation to be obvious and the required text and graphic content cannot be printed in the low depression of the corrugation. For the uneven surface of the corrugated cardboard caused by the exposed corrugation, it is necessary to select a flexible resin plate with good elasticity as the printing plate to overcome the defects of unclear printing and exposed bottom. Especially for the A-type corrugated cardboard produced by low grammage paper, the flat pressure strength of the corrugated cardboard will be greatly damaged after printing by the printing machine. In addition, the edge pressure strength of the corrugated cardboard will also be greatly damaged after passing through the printing roller and the pressure roller.
If the surface roughness of the corrugated cardboard is too different, it is also easy to cause the corrugated cardboard produced by the corrugated cardboard line to curl. Curved paperboard can cause misregistration and printing slotting regulations, so curved paperboard should be pressed flat before printing. If the corrugated cardboard is printed forcibly, it is easy to cause regulations. It will also cause a decrease in the thickness of the corrugated cardboard.
2. The problems caused by different surface roughness of the original paper
In printing on the original paper with a rough surface and loose structure, the ink permeates well and the printed ink dries quickly, while on paper with a smooth surface and dense and tough fibers, the ink dries slowly. Therefore, on rougher paper, the ink application should be increased, and on paper with a smooth surface, the ink application should be reduced. Ink dries quickly on paper without size, but it dries slowly on paper with size, but the reproduction of printed patterns is good. For example, coated whiteboard paper dries slowly because its ink absorption is smaller than that of boxboard paper and tea board paper, and it is also smoother than boxboard paper, coated paper and tea board paper, so the resolution of printing small dots on it is also high, and the reproduction of its patterns is also better than that of coated paper, boxboard paper and tea board paper.
Three, problems caused by the difference in absorption of the original paper
Due to the difference in raw materials for paper making and the difference in coating, calendering and coating of the original paper, there is a difference in the absorption energy, for example, when the single-sided coated whiteboard paper and the kraft paper are printed on the same machine, because of the low absorption performance, the drying speed of the ink is slower, so the concentration of the ink in the previous color should be reduced and the viscosity of the ink in the later color should be improved. And place the lines, text, small patterns in the first color printing, and place the full-page solid color in the last color printing, so as to improve the overprint effect. In addition, place the dark color in the front printing, and place the light color in the back printing, so as to cover the registration error, because the dark color has strong coverage, which is conducive to the registration standard, and the light color has weak coverage, and even if there is a deviation in the back printing, it is not easy to observe.
The different degree of coating on the surface of the original paper will also affect the amount of ink absorbed. The paper with less coating absorbs more ink, and the paper with more coating absorbs less ink, so the gap between each ink roller should be adjusted according to the coating state of the paper, that is, to control the amount of ink on the plate, the gap between each ink roller should be adjusted smaller. It can be seen that the absorption performance of the original paper should be tested when it enters the factory, and the absorption performance parameter of the original paper should be given to the printing slurry machine and the ink matching personnel, so that they can match the ink and adjust the equipment. And adjust the viscosity and PH value of the ink according to the absorption state of different original papers.
