Causes of paper pleating in the printing process

With the rapid development of the modern society's commodity economy and the continuous improvement of living standards, people are increasingly demanding products such as packaging effect, printing quality, and beauty. As a result, gravure printing with features such as full color, thick imprinted ink layers, and a wide range of applications has been rapidly developed in the packaging and printing industry, and has occupied a greater proportion in the printing market in its unique manner.

At present, in domestic gravure paper printing, almost two-thirds of the printed products are printed on thin paper. Among them, the typical soft packs of cigarette packs used mostly 80 to 90 g/m2 single-sided coated paper. Another is the use of 30 ~ 50g/m2 tipping paper printed paper cigarette tipping paper and 70-80g/m2 single-sided coated paper printed beer label. In the process of gravure printing of such thin paper, there are more printing defects than thick paper, such as the high scrap rate caused by the pleating and curling of thin paper, and the large consumption of raw materials, etc., all of which bring large economic losses to printing enterprises. The printing operator has a lot of headaches. In order to improve the quality of product packaging, to create a higher social value and economic benefits.

Paper pleating refers to the "folding" phenomenon that occurs in the direction of web travel in the printing process. The wrinkles of the thin paper are related to the width of the gravure printer and the thickness of the paper. The larger the width, the higher the chance of wrinkling. The thinner the paper, the smaller the amount, the higher the chance of creases.

In the process of tissue gravure printing, once this failure is discovered, the printing pressure at both ends of each printing unit should first be considered to be uniform. Check the impression roller carefully to see if there is a problem that the pressure at one end is high and the pressure at the other end is small. For the problem of pleating caused by printing pressure, it is necessary to prevent it in advance and do a good job in the basic work before printing. Before each official start-up printing or overprinting, it is necessary to carefully adjust the embossing rollers of each unit, and on the basis of achieving the printing requirements of the product, the pressure at both ends of the roller is uniform, and the pressure of the front and rear units is constant. The size should not be too different.

In addition, the paper change roll operation is also likely to cause the paper to wrinkle. Regardless of whether the paper is automatically fed or manually fed, if the newly replaced paper roll is not aligned with the paper roll being printed and the deviation is large, wrinkles are likely to occur. This is mainly due to the interface between the front and rear paper rolls. Paper tension and printing pressure caused by the joint action. It is advisable to reduce the printing speed appropriately and adapt it for a certain period of time without affecting overprinting each time the paper is received.

Another factor is that after the web is removed from the cowhide packaging, the paper on the paper roll will expand and wrinkle due to the absorption of moisture from the air. When these outer wrinkled papers enter the printing, there will be problems. In order to avoid such problems, it is recommended that the paper roll strictly guarantees the integrity of the package during transportation and storage. When used in a production shop, the print operator should not prematurely remove the overwrap of cowhide overwrap. Because each thin paper roll has more than 10,000 meters, the printing time is about 50 to 60 minutes, and it takes only 5 minutes to prepare the next roll, so there is enough time to prepare the next paper to be printed. The volume will be removed immediately after printing, and the time it takes for the paper roll to absorb moisture in the air will be minimized to avoid unnecessary trouble.