How to increase humidity when printing kraft paper tape!

The kraft paper tape manufacturer introduced that the deformation problem of kraft paper tape can be eliminated after humidification and conditioning during printing, which is of great significance to the flatness and dimensional stability of kraft paper tape, as well as the calendering finishing, printing, cutting and packaging of subsequent processes. What are the common methods of humidifying and adjusting kraft paper tape?

 

Moisture control, the moisture content of paper is expressed by the weight of water in the paper and the weight of paper. When the moisture content of the paper changes by 0.1%, overprint will be affected. Generally speaking, the moisture content of kraft paper tape should be controlled at 7% ± 1%, and the moisture content error between the paper center and the paper periphery should not be greater than 1%.

 

Generally, when printing kraft paper tape, it is necessary to air the paper to make the humidity and temperature of kraft paper tape suitable for printing. The specific method is to transport the paper to the printing workshop 24 hours in advance or put it in a workshop with similar temperature and humidity to the printing workshop for use.

 

The best way is to humidify the paper drying room which is 6% - 8% higher than the relative humidity of the printing workshop, or put it in the wet place first, and then carry out the moisture balance in the printing workshop, so as to make the moisture content of kraft paper tape uniform and stable, so as to achieve the best printing effect.

 

One of the methods to control the humidity of kraft paper tape is active humidification. According to the principle of water ink separation in offset printing, the kraft paper tape is deformed due to moisture absorption. According to the lag effect of moisture change of kraft paper tape, the kraft paper tape is printed with water once before formal printing, and the moisture content of kraft paper tape is increased actively, so that the kraft paper tape has a pre moisture absorption In this way, the deformation of kraft paper tape will be much smaller in the formal printing.

 

After offset printing, especially UV printing, kraft paper tape is in the process of dehumidification due to the influence of drying temperature, and its size is usually smaller.

 

After laminating or off-line glazing, the size deformation of kraft paper tape is larger due to the influence of high strength heat.

 

The above is to improve the stability of kraft paper tape by adjusting the state of kraft paper tape. In addition, it is also necessary to properly handle the printing setting to compensate the deformation of kraft paper tape to ensure the printing quality.