There are many reasons for bubbles to be generated during screen printing of silicone rubber. Here are some of the main factors:
Ink problems:
Ink viscosity that is too high or too low may cause bubbles to be generated. If the viscosity is too high, the ink will have poor fluidity, be difficult to spread, and easily generate bubbles; if the viscosity is too low, the ink may evaporate easily during the printing process, generating bubbles.
The ink contains impurities or bubbles, which may remain on the surface of the substrate during the printing process.
Substrate problems:
The surface of the substrate is uneven, and there are oil stains, dust or moisture, which will affect the adhesion and spreadability of the ink, thereby generating bubbles.
The poor compatibility of the substrate material and the ink may also cause bubbles to be generated.
Printing process problems:
If the printing speed is too fast and the ink fails to fully wet the surface of the substrate, bubbles may appear.
Uneven printing pressure or too large a gap between the squeegee, screen and substrate may also cause bubbles to be generated.
Improper stirring or shaking of the ink during printing may also cause bubbles to be mixed into the ink.
Environmental factors:
The temperature and humidity of the printing environment have a great influence on the drying speed and fluidity of the ink. If the temperature is too high or the humidity is too high, the solvent in the ink may evaporate too quickly, causing the ink surface to conjunct too quickly and the internal bubbles cannot be discharged.
Equipment problems:
The lack of precision and stability of the printing equipment may cause the ink to not spread evenly during the printing process, resulting in bubbles.
Insufficient cleaning and maintenance of the equipment may also cause impurities or bubbles to be mixed into the ink.
In order to reduce or eliminate the bubble problem during screen printing silicone printing, you can start from the above aspects, such as adjusting the viscosity of the ink, cleaning the surface of the substrate, optimizing the printing process, controlling the printing environment, inspecting and maintaining the printing equipment, etc. At the same time, you can also consider using a defoamer to reduce bubbles in the ink.