1. The problems caused by low grammage paper.
When low grammage paper is used as the surface paper of corrugated cardboard, it will appear that the surface of the corrugated cardboard is exposed to the corrugation marks. It is easy to cause obvious corrugation and the required text and graphic content can not 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 being printed 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
Printing on the original paper with a rough surface and loose structure, the ink permeability is large, the printed ink dries fast, and on the paper with a high degree of smoothness and dense and tough fibers, the ink dries slowly. Therefore, on the rough paper, the ink application should be increased, and on the smooth paper, the ink application should be reduced. The ink dries fast on the paper without size, but it dries slowly on the paper with size, but the reproduction of the printed pattern is good. For example, the coated whiteboard paper has a lower ink absorption than the boxboard paper, tea board paper, so the ink dries slowly, and its smoothness is higher than the boxboard paper, the newsprint, the tea board paper, so the resolution of printing the small dots on it is also high, and its pattern reproduction is also better than the newsprint, the boxboard paper, the 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 absorption energy, such as when overprinting is performed on single-sided coated whiteboard paper and kraft paper, because of the low absorption performance, the drying speed of ink is slower, so the concentration of ink in the previous color should be reduced and the viscosity of 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 over印 effect, and also 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 if it is placed in the back printing.
The different degree of coating on the surface of the original paper will also affect the amount of ink absorbed by the ink marks. The paper with less coating absorbs more ink, and the paper with more coating absorbs less ink, so the gap of 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 of each ink roller should be adjusted smaller. It can be seen that the original paper should be tested for its absorption performance when it enters the factory, and a parameter of the absorption performance of the original paper should be given to the printing creaser 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.
