Why the last printing no need baking dry before coating high glossy silicone?
1. Avoiding Poor Adhesion Between Silicone and Ink Layers
Silicone curing depends on surface cleanliness: Silicone, especially liquid silicone rubber (LSR), requires a clean and receptive surface for proper curing and adhesion. If the final printed layer is baked, the ink surface may form an overly smooth or dense film, which can reduce silicone adhesion.
Residual solvent issues: Some inks may retain trace amounts of solvent after baking. These volatile compounds can slowly release after silicone is applied, leading to bubbles or delamination in the silicone layer.
2. Impact of Silicone Curing Temperature
Secondary high-temperature conflict: Silicone requires high-temperature curing (e.g., 120°C–180°C). If the printed layer has already been baked, the second exposure to high heat during silicone curing may cause the ink to discolor, become brittle, or peel off.
Differences in thermal expansion coefficients: Multiple baking steps can exacerbate the mismatch in thermal expansion between the ink and the substrate (such as PC or PET), leading to warping or cracking.
3. Process Efficiency Optimization
Reducing process time: Omitting the final baking step can shorten the production cycle, especially in assembly line operations. The overall curing process after silicone application can simultaneously stabilize both the ink and the silicone layer.
4. Adaptability of Special Inks
Non-curing inks: Certain inks designed for silicone applications (such as elastic inks or UV inks) are formulated to cure concurrently with the heat or UV exposure used for silicone, eliminating the need for separate baking.
Summary
The core purpose of skipping the final baking step is to maintain surface activity of the printed layer, ensuring strong silicone adhesion while avoiding thermal stress or chemical residue issues. In actual production, adjustments should be made based on the type of ink, silicone material, and process flow (refer to the technical data provided by suppliers).