If the glossy cover screen printing silicone is dried immediately after printing, bubbles will be generated. The main reasons are as follows:
1. Gas release inside the silicone
Chemical reaction produces gas: During the curing process of silicone, chemical reactions may occur, such as cross-linking reactions, which will produce gas (such as water vapor, low molecular volatiles, etc.). If high-temperature baking is performed immediately, the chemical reaction inside the silicone will be accelerated, resulting in faster gas production, and the rapid curing of the silicone surface will form a dense film to prevent gas from escaping, thereby forming bubbles inside the silicone.
Uneven mixing of silicone: During the preparation of silicone, if additives such as curing agent and diluent are not mixed evenly with the silicone base material, it may cause inconsistent local curing speed, resulting in gas aggregation and bubbles.
2. Process operation factors
Printing thickness and speed: Too thick printing thickness or too fast printing speed may cause the silicone to fail to fully level during the printing process, and there will be air or gas inside. Immediate high-temperature baking will prevent these gases from escaping in time, forming bubbles.
Environmental humidity and temperature: Too high humidity or too low temperature in the printing environment may also affect the curing process of silicone and the generation of bubbles. For example, high humidity may cause the silicone to absorb moisture, which evaporates during the baking process to form bubbles.
3. Silicone Material Characteristics
Viscosity and fluidity: The viscosity and fluidity of silicone will affect its filling and leveling performance during the printing process. If the viscosity of the silicone is too high or the fluidity is insufficient, it may cause air or gas inside the silicone after printing.
Curing characteristics: Different types and brands of silicone have different curing characteristics and curing times. If the selected silicone cures too fast or the curing temperature range is not suitable, it may also cause bubbles.
4. Solutions and preventive measures
Optimize the printing process: Adjust parameters such as printing thickness, speed and pressure to ensure that the silicone can fully level and fill every detail of the printed pattern.
Control environmental conditions: Keep the printing environment dry and at a suitable temperature to avoid the influence of high humidity or low temperature on the silicone curing process.
Choose the right silicone material: Choose the right silicone type and brand according to specific needs to ensure that its curing characteristics and curing time meet the process requirements.
Use a step-by-step curing process: After printing, let the silicone level naturally at room temperature to a dry state, and then bake at high temperature for curing. This can reduce the generation and accumulation of gas inside the silicone.