Sometimes bubbles will appear on the silicone printing ink of the substrate after printing. The main reasons for the bubbles are as follows:
①Poor pre-printing treatment of the substrate. Dust, oil stains and other substances are attached to the surface of the substrate.
②Bubbles in the silicone printing ink. When adding solvents and additives to adjust the ink and stirring, some bubbles will be mixed into the ink. If left alone, the ink with low viscosity will naturally degas, while some inks with high viscosity cannot degas naturally. Some of these bubbles will naturally disappear during printing due to the transfer of ink, while others will become larger and larger. To remove these bubbles, defoamers should be used. The amount of defoamers added to the ink is generally about 0.1-1%. If it exceeds the specified amount, it will play a foaming role.
Even if the ink bubbles after transfer, as long as the substrate is wet and the fluidity of the silicone ink is good, the bubbles on the surface of the printed ink film will gradually disappear, and the ink will form a flat printed ink film. If the bubbles in the ink are not eliminated, the ink film will form a ring-shaped uneven film surface. Generally, bubbles in the ink can be degassed due to the effect of the screen when passing through the screen. In addition, hot water or boiling water will have a better defoaming effect when mixing and stirring the ink.
Red, blue, green and other transparent inks have a small proportion of organic pigments in the microparticles, and the binders of these inks have the characteristic of easy foaming. If the corresponding diluent, thickener or detackifier is added, the ink can also be converted into a stable ink with good printing suitability.
③ The printing speed is too fast or the printing speed is uneven. Appropriately reduce the printing speed to maintain the uniformity of the printing speed.
If the above measures cannot eliminate the bubbles in the printed product, consider using other types of silicone printing inks.