Causes and solutions of powder sticking to PET film
1. Air humidity (reference value 40%-70%)
Air humidity mainly affects the powder sticking to the film during storage, printing, and powder shaking. There is no feedback that it has an impact on the pressing process.
a) The high humidity of the storage environment will cause the PET film and hot melt powder to be damp. The absorption of moisture will cause excess hot melt powder to stick during the process of dusting and shaking, which will affect the effect of the finished product.
Solution: When storing the film and powder, it should be stored in a cool and dry place, and a desiccant can be placed if necessary. Turn on the air conditioner during the use of film and powder to ensure the stability of indoor temperature and humidity.
b) If the air humidity in the printing environment is low and the air is dry, static electricity will be caused during the printing process, and ink will be splashed during printing (mainly in the process of white ink jetting). In the process of shaking powder, the splashed ink will stick to Powder, which remains on the film, affects the look and feel of the finished product.
Troubleshooting method: print two copies of a picture, one in normal white color, and one in color only. Then dust and dry for comparison. If the sticky powder with white ink is serious, it proves that it is caused by electrostatic splashing.
Solution: The problem of static electricity can be effectively solved by humidifiers, static removal rods, etc. Or adjust the printing speed to reduce the white ink output.
3) The powder is damp during the shaking process
Troubleshooting method: After eliminating the reasons for storage and static electricity, you can check whether too much powder is sprinkled, which causes the remaining powder to be damp during the powder shaking process. In the process of shaking powder, hot melt powder mainly relies on absorbing water to stick to the film. In the end, only a portion of the powder can be absorbed into the ink and stick to the pattern, and the excess powder is shaken off. During this process, the excess powder is absorbed by the ink moisture and the moisture evaporated during the pre-heating and drying of the film, which may cause it to stick to the film and not shake off.
Solution: replace this part of the powder and dry it. Dust with new powder. At the same time, control the amount of dusting during the dusting process, not too much.
2. Coating density of film and fineness of powder
The coating density of the film is small and the powder is fine, which will cause the powder to get stuck in the coating hole of the film and cannot be shaken off. If the coating density of the film is high, the powder is not too fine, the powder will not get stuck in the coating holes, and the shaking of the powder shaker will not shake it clean.
Solution: Increase the shaking force of the powder shaker, or tap the back of the film hard when shaking the powder manually. Looking for suppliers of stable PET films and powders. This question is not simply to compare the density of the coating and the fineness of the powder, but it mainly depends on the compatibility of the powder and the film. After many screenings and comparisons, TODOjet has selected the most suitable film and powder for TODOjet DTF printer, which are suitable for various application scenarios and fabrics. Welcome to consult and purchase.
3. Printing speed and front and rear heating
When printing, many customers will turn on the high-speed printing mode. When the film has not completely absorbed the ink, it has already reached the process of dusting and shaking, resulting in excessive moisture. When the film is not dry, the remaining powder absorbs water and finally sticks to the film.
Solution: Wait for the front and back heating to the rated level, and print at a speed of 6pass-8pass, which can ensure that the film is not damp and absorb ink stably.