With the development and progress of society, the printing industry has also developed by leaps and bounds. The advent of commercial rotary presses has put forward new requirements for printing paper in terms of temperature resistance. Because ordinary coated paper cannot meet the printing requirements of this emerging printing method, blistering has become a more serious and common problem in rotary printing. 1. The principle of foaming The rotary printing machine has the characteristics of high-speed printing, generally up to 40,000 to 50,000 sheets per hour (and the general lithographic printing is only over 10,000 sheets / hour at the fastest), and direct folding is performed after the printing is dried, at such a fast speed Next, in order to prevent printing abnormalities such as ink drying and back sticking, rapid drying of printing ink is required, and the most effective method for rapid drying of ink is high temperature heating, so there is an oven in the structure of the rotary machine. The printed paper is heated to make the ink dry quickly. A certain amount of water, and the water becomes steam when the high temperature drying (drying temperature is generally around 140 ℃) is released. However, if full-page printing is performed at the same position on both sides of the paper, and the amount of ink is large, the water vapor cannot be released outwardly due to the ink completely covering the paper surface, thereby causing blistering. (See Figure 2). 2. Several important factors affecting the foaming of the rotary machine: According to the above foaming principle, we can summarize three aspects that affect the foaming of rotary printing: printing conditions, inks, and paper. Among them, the main factors related to printing are as follows: 1. Drying temperature and printing speed of printing press Because the speed of rotary printing is faster, the residence time of the paper in the oven is also shorter. In order to ensure the normal drying of the ink and prevent the occurrence of back printing, it is necessary to increase the drying temperature and accelerate the drying of the ink, but according to the gas Expansion theory, under certain pressure (P1 = P2), the higher the temperature (T2> T2), the larger the volume (V2> V1), so during the printing process, if the drying temperature is too high, blistering will occur Problem, but if the drying temperature is too low, it will cause problems such as back printing due to the ink not drying. 2. Drying performance of ink The ink used for rotary printing is special ink. Therefore, due to the characteristics of the ink's fluidity and dryness, it has a greater influence on the foaming of the rotary paper. The easier the ink is to dry, the lower the drying temperature of the rotary machine is, and the less likely it is to foam. The gloss will generally be relatively low. 3. Printing conditions in rotary printing. The requirements of paper and ink will be higher and higher, and its main development trend: with the increase of printing efficiency requirements. The printing speed of the rotary machine will be faster and faster, and the drying temperature will be higher and higher, so the requirements for ink and paper will be higher and higher. On the one hand, the printing ink is required to ensure the gloss after printing. Under the premise, it can be dried faster, on the other hand, it requires printing paper to continuously improve its temperature resistance. According to the needs of market development, Jindong Paper has researched and developed rotary coated paper as early as a few years ago, and it is constantly improving the process conditions. Its main advantages: Jindong Paper Co., Ltd. has adopted aspects such as paper cohesion, air permeability and coating formulations. The adjustment of the paper improves the cohesion of the paper and the absorption of ink to achieve the purpose of high temperature resistance of the paper product. At present, the special paper for rotary machine produced by Jindong Paper can ensure that no foaming problem will occur under high-speed printing conditions, thereby enabling customers to improve production efficiency and post-print quality. At the same time, Jindong Paper will always rely on advanced technology and equipment. Walking in front of the market, by continuously improving the quality of paper, to meet customers' increasing demand for printing speed. Sketching Chair Set,Sketching Chair,Sketching Chair With Tablet,Training Chair With Tablet AU-PINY FURNITURE CO., LTD , https://www.au-piny.com
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On the foaming problem of special coated paper for rotary machine