Binary Printing: Analysis and Elimination of Paste Blanket

When printing off-site or large-area graphic products with poor quality offset paper, the phenomenon of paste blanketing is likely to occur, which is a headache for operators. Paste blankets not only affect the production speed, increase the labor intensity, and waste raw materials, but also pay little attention to quality accidents. Below, the author analyzes the phenomenon of paste blanket caused by various reasons encountered in the work.

1. Printing pressure is too small

The printing process is a process in which the printing plate selectively adsorbs the ink and transfers the ink to the printing material through the blanket. However, due to the addition of paper and paper powder, the transfer of ink is hindered, so that the ink cannot be smoothly transferred to the substrate but remains on the blanket. By appropriately increasing the pressure between the three rollers, forcing the ink to be transferred to the substrate unconditionally, the problem of the paste blanket can be solved. However, while increasing the pressure between the rollers, it is also necessary to consider the printing plate's resistance to printing. When printing large quantities of products, baking can be done to increase the printing plate's resistance to printing.

2. Eraser layout uneven

If the blankets and pads are used for too long, irregularities will appear. It is easy to pile up paper and paper powder in the sunken place, causing a partial paste blanket. In the sunken place, wipe the reducing agent or use 1 or 2 layers of transparent plastic tape to stick to the back of the blanket to restore it to a flat surface. If you can't solve the problem of the local paste blanket, you can only replace the blanket and pad.

3. Poor flow of ink

If the fluidity of the ink is not good or too viscous, the peeling force on the surface of the paper will increase, and the paper surface and the paper powder on the surface of the paper can be easily peeled off and transferred to the printing plate, ink roller or ink through the blanket. Slots create a vicious circle. When printing large quantities of products, timely cleaning should be performed according to the amount of paper and paper powder in the ink roller, ink tank, and so on, which can also guarantee the printing plate's resistance to printing forces.

Adding an appropriate amount of auxiliary material (No. 6 oil or thinner) in the ink can increase the fluidity of the ink, and then add an appropriate amount of the diluting agent, which in turn increases the ink's activity, so that the ink can be transferred to the printing well. On the object, reduce the phenomenon of paste blanket.

Encountered above, some operators will mistakenly believe that adding an appropriate amount of sizing agent can increase the fluidity of the ink, but at the same time, adding the sizing agent also reduces the motility of the ink and makes it stick on the plate and eraser. The ink on the cloth is difficult to clean, and the phenomenon of sticking blankets will not be reduced.

4. The arrangement of printing color sequence is unreasonable

If it is a four-color machine, you can use a small amount of text and a small amount of ink on the front to keep paper and paper powder on the previous print.

The reasons for sticking blankets are various. The above points are some of the experiences that the author has summarized in practice and are for reference only by peers.

Source: Ke Yin Network