Influence of abnormal moisture content of the hott

2022-08-06
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The process practice shows that the material is a homogeneous core material provided according to the requirements of the new national standard issued by the state. The test results show that there are many reasons affecting the printing quality, among which the abnormal water content of the paper is also the reason affecting the printing quality of the product. Therefore, correctly understand the relationship between the water content of the paper and printing, and accurately control the water content of the paper, It plays an important role in ensuring the printing quality. As we know, paper is composed of fiber, filler and rubber. When the oil circuit is not smooth due to the ring, and the ambient temperature and humidity changes, the water content of the paper is excessive, the binding force between the fiber, filler and rubber in the paper is easy to be reduced, which will inevitably affect the surface strength of the paper. In this way, during the printing process, it is easier to produce poor conditions such as de dusting and paper dust, thus reducing the hardness and stiffness of the paper edge. During the paper feeding, it is also easy to produce unstable pre position positioning and lead to overprint misalignment. On the contrary, if the water content of the paper is too low, the elasticity of the paper is poor, and the expansion rate of printing points and imprints is large. During the printing process, the paper is also prone to moisture absorption variation, resulting in inaccurate overprint

if the moisture content of the paper is uneven, various printing defects will also occur. If the water content around the paper is about 1.4% higher than that in the middle, the overprint gauge line at the rear trailing tip of the paper will be 1mm longer than its mouth; If the water content is higher than 2.5%, the back trailing tip of the paper will produce printing wrinkle, and the back trailing tip overprint gauge line will be 2mm longer than its mouth, and the pictures and texts in the printed sheet will also be inaccurate; If the water content is higher than 3%, the paper will appear Ruffle phenomenon, which will cause serious folding during printing; If the water content of the paper is high and the relative humidity of the printing site is low, the four sides of the paper are easy to release water, so that the water content of the central part of the paper is more than 2.5% higher than that of the four sides, the paper will have a tight edge, and it is easy to duplicate the pictures and texts in the middle part during printing

various conditions clearly show that whether the water content of paper is normal or not has a great impact on the printing quality. Therefore, the moisture content of the base paper should be mastered before hanging the paper, so that the moisture content of the center and four sides of the paper after hanging and drying can be kept uniform. For this reason, the paper thickness of each clip should be controlled. The graphic paper dryer used by our factory hoists about 70g/m2 of paper. Each clip contains about 70 sheets. Basically, the air volume can be blown to the center through the paper gap to achieve uniform blowing, so as to ensure that the moisture content of the paper is basically the same and ensure the printing quality

to sum up, the water content of paper has a significant impact on the printing quality. Controlling the water content of paper is a necessary measure to check the source of printing quality. It is of great significance to ensure normal printing and reduce the chance of printing failure and paper loss. That being the case, to what extent is the moisture content of the paper appropriate? Generally speaking, if the moisture content of the paper is controlled within 7 ± 1%, it will be subject to fair sanctions by national laws, and the moisture content difference between the center of the paper and the four sides is not more than 1%. Basically, the two methods of displacement calibration can ensure normal printing and avoid failures

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