About the foaming problem of the special coated paper for the rotary machine
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
With the development and progress of society, the printing industry has also developed by leaps and bounds. The advent of commercial rotary presses has placed new demands on the temperature resistance of printing paper. Because ordinary coated paper can not meet the printing requirements of this new printing method, foaming has become a more serious and common problem in rotary printing.
First, the principle of foaming
Rotary printing presses have the characteristics of high-speed printing, generally 4 to 50,000 sheets per hour (and the average lithographic printing is only 10,000 sheets per hour), and direct folding after printing and drying, at such a fast speed In order to prevent the printing abnormality such as ink dryness and back sticking, the printing ink needs to be quickly dried, and the most effective method for quickly drying the ink is high temperature heating, so there is an oven in the structure of the rotary machine, The printed paper is heated to allow the ink to dry quickly.
The water is quantified, and the water is released to the outside when the water is dried at a high temperature (the drying temperature is generally around 140 ° C). However, if the printing is full at the same position on both sides of the paper, and the amount of ink is large, the water vapor cannot be released outward due to the ink completely covering the paper surface, thereby generating foaming.
Second, several important factors affecting the blistering of the rotary machine:
According to the above foaming principle, we can summarize three aspects that affect the printing and printing foaming: printing conditions, ink, paper, and several major factors related to printing are as follows:
1. Printing machine drying temperature and printing speed
Because the speed of the rotary printing is faster, the residence time of the paper in the oven is also shorter. To ensure the normal drying of the ink and prevent the generation of the back printing, it is necessary to increase the drying temperature and accelerate the drying of the ink, but according to the gas. Expansion theory, when the pressure is constant (P1=P2), the higher the temperature (T2>T2), the larger the volume (V2>V1), so during the printing process, the drying temperature is too high, and foaming will occur. The problem, but if the drying temperature is too low, there will be problems such as back printing due to the ink not drying.
2. the drying performance of the ink
The ink used for rotary printing is a special ink. Therefore, in terms of the fluidity and dryness of the ink, the foaming effect of the rotary paper is greatly affected, the ink is more easily dried, the lower the drying temperature of the rotary machine, the less likely to foam, but the ink that dries too fast, after printing Gloss is generally relatively low.
Third, the printing conditions in the rotation printing. The requirements for paper and ink will be higher and higher, and its main development trend: with the improvement 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. Therefore, the requirements for ink and paper will be higher and higher. On the one hand, printing ink is required to ensure the gloss after printing. Under the premise, it can be dried more quickly, and on the other hand, the printing paper is required to continuously increase its temperature resistance. By adjusting the cohesion, air permeability and coating formulation of the paper, the cohesion and ink absorption of the paper can be improved to achieve the purpose of high temperature resistance of the paper.