INK ODOR PROBLEM

More than 20 years ago, when people in Shanghai were burning coal stoves, they often put a small chimney nearly 1 meter high on the stoves. At this time, even if there was no fan to fan the air, the wind and fire of the stoves were flourishing. This is what happens when you use the differential pressure properly. The exhaust system should also make reasonable use of this pressure difference. Of course, the most thorough way is to replace the ink, with the solvent residue as small as possible to replace the polyamide ink.

Gravure printing process according to the printing process is composite to choose different inks. If you want to compound after printing, whether it is dry compound or extruded compound, all ink is wrapped in two layers of film and sandwiched in it, known as printing ink, or composite ink. On the contrary, the printing is not composite, and no matter which side of the ink layer in the film, are called surface printing ink. Table printing ink can be printed on the inside of the transparent film, first black, blue, red, yellow colors, and finally with a white backing, make full use of the reflective characteristics of the film, so that the printed surface is brighter. A few years ago the popular gravure plastic calendar and these years of PVC thermal shrinkable film label, are the use of this process successful examples. There will also be table printing ink printed on the opaque OPP label film, instead of paper label, such as Coca-Cola, Pepsi, rising sun beverage and other PET bottle stickers.

In addition, because the film can not be supplemented by light, surface printing ink must emphasize their luster. However, polyamide resin has a problem, that is, its residual solvent is too large. Because the plastic gravure printing process is mainly by hot air to dry, hot air to dry the ink surface, the drying mechanism is from the outside dry, from the outside in, gradually dry out. But since the outside dries first, the membrane forms first. The formation of this layer of film, although to avoid the next color group printing ink stick, but also prevent the inner layer of solvent emission. Therefore, the use of polyacyl skin ink printing, in order to make the ink thoroughly dry, the hot air should be properly opened larger, the speed can not be too fast. To remove as much residual solvent as possible. Otherwise, we often meet this situation in our daily production. A roll of finished products printed down, packaged into the box, after a period of time to open, a pungent smell on the face, this is often recruited to customer complaints of residual odor problem.

To solve this problem, we suggest that on the basis of not changing the ink, take the following measures:

1. Appropriately increase the drying temperature, slow down the speed, so that the solvent volatilization is sufficient;

2. Check the exhaust gas system of gravure printing machine, check the air inlet pressure and the air outlet pressure, refer to the data provided by the printing machine manufacturer, make the pressure difference as large as possible.

Sometimes, the heat has been opened too much, but the smell is still there, at this time, it is necessary to check the wind pressure, if only the temperature and no qualified wind pressure, the solvent is still not very good volatile. Pay attention to check whether the air duct is smooth. In the days of low pressure, the exhaust system itself can not meet the process requirements, then we should 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 the manufacturers. The installation position of the exhaust chimney and the height of the air inlet and outlet will directly affect the exhaust efficiency.