Gravure Blocking Analysis

In gravure printing, the transfer rate of the ink is generally 60% to 80%, and 2/5 to 1/5 of the ink will remain in the cells. When the ink transfer rate decreases, the printed image will be blurred and the writing will be blurred. The lines are unclear, especially in the shallow part. When the blockage is severe, normal production will also be affected. The main reasons for blockage are as follows:

(a) Causes of Ink

1. High ink viscosity, uneven distribution of ink in ink, poor leveling.

2. The solvent volatilizes too fast, or the solvent used is not very soluble to the pigment.

3. The depth of the printing plate immersed in the ink tank is not enough and the ink is bad.

To solve this problem, we need to properly reduce the viscosity of the ink, or use a slow-drying mixed solvent to reduce the solvent evaporation rate. Increase the ink tank position.

(B) The cause of the scraper and its solution

1. The squeegee is in an improper position and the squeegee is too far away from the embossing point.

2. The blade angle is too large or the blade pressure is too high.

To solve this type of blockage problem, it is necessary to properly adjust the pressure of the blade and the angle of the blade, so that the blade is closer to the embossing point, and prevent the hot air in the drying box from leaking out of the platen.

(3) Reasons and Solutions for Printing Plates

1. When the printing plate is used, the down time is too long or the plate hole of the printing plate is not cleaned after the last printing. The plate hole of the printing plate is dried by the ink, resulting in blocking the plate.

2. The depth of the plate is too deep, and the net cleaning is not clean, resulting in blockage.

3. The printed version is of poor quality and the cyberspace is inverted.

With this type of problem, the plate should be rechromed.

(d) Other causes and solutions

When the pressure is too light or the printing speed is fast and the imprinting time is short, resulting in blockage, the pressure should be increased appropriately.

Higher ambient temperature or lower relative humidity, more dust in the air, due to electrostatic dust and other reasons can also lead to blockage, so to maintain a clean working environment can also reduce the generation of blockage phenomenon.