In the gravure printing process, different inks are selected according to whether the post-printing process is compounded
If it needs to be compounded after printing, whether it is dry compounding or extruding compounding, all the ink is wrapped by two layers of film and sandwiched in it, called Liyin ink, or compound ink. On the contrary, it does not compound after printing, and no matter which side of the film the ink layer is on, it is called surface printing ink. The surface printing ink can be printed on the inside of the transparent film, and the black, blue, red, and yellow colors are printed first, and then the white plate is used as the backing, making full use of the reflective characteristics of the film to make the printed surface brighter.
The gravure plastic calendar that was popular in the past few years and the PVC heat shrinkable film labels in recent years are successful examples of using this process. There are also printing inks printed on opaque OPP label films to replace paper labels, such as bottle stickers for PET bottles such as Coca-Cola, Pepsi, and Rising Sun.
To solve this problem, we recommend taking the following measures without changing the ink:
1. Properly increase the drying temperature and slow down the vehicle speed to make the solvent volatilize fully;
2. Check the exhaust system of the gravure printing machine, check the inlet pressure and outlet pressure, and refer to the data provided by the printer manufacturer to make the pressure difference as large as possible.
Sometimes, the heat has been turned on a lot, but the smell is still there. At this time, it is necessary to check the wind pressure. If there is only temperature and no qualified wind pressure, the solvent is still not volatile. Pay attention to check whether the air duct is smooth. On days when the air pressure is relatively low, the exhaust system itself does not meet the process requirements. At this time, it is necessary to check the rationality of the exhaust system.
Because the exhaust system of the machine is designed by the manufacturer, but the equipment is installed in the factory, it depends on the technical strength of each manufacturer. The installation position of the exhaust chimney, the height of the air inlet and the air outlet will directly affect the level of the exhaust efficiency.
The exhaust system should also make reasonable use of this pressure difference. Of course, the most thorough way is to replace the ink and replace the polyamide ink with the smallest amount of solvent residue.
Recommend several inks from Dalian Schmidt Ink Company (DSPI) based on experience. DSPI's PA-C ink is alcohol-soluble ink, and the connecting material is polyvinyl butyral resin, which can be used for gravure printing and flexographic printing. The solvent is a mixture of alcohols, and the ink contains no ethyl ester.
When the ink is used for surface printing, a special wax compound needs to be added to the ink, which can withstand a high temperature of 110 ℃, and is suitable for paper, plastic and aluminum. The heat-sealed OPP and pearlescent film mentioned in Ms. Zhang's letter can be used completely.
DSPI's MV-F-KA series inks, the connecting material is nitrocellulose, alcohol-soluble, surface printing, high temperature resistance up to 160 ℃.
