The screen used for plastisol cannot be directly used to print silk screen silicone due to significant differences in material properties and printing process requirements.
Key Reasons:
Material Properties:
Plastisol is a PVC-based ink with a relatively low viscosity, suitable for coarse mesh screens (e.g., 60-120 mesh).
Silicone ink (silk screen silicone) is a high-viscosity, high-elasticity liquid silicone that requires a higher mesh count (e.g., 150-300 mesh) to ensure uniform ink passage and fine pattern reproduction.
Screen Parameters:
Mesh Count: Silicone ink demands a higher mesh count to prevent clogging and ensure precise ink transfer.
Screen Tension: Silicone ink requires higher screen tension (20-30 N/cm) to maintain printing accuracy and uniformity.
Mesh Material: Silicone ink may require corrosion-resistant mesh materials (e.g., polyester or stainless steel) to withstand its chemical properties.
Printing Process Differences:
Scraper Pressure: Silicone ink requires higher scraper pressure to fully fill the screen and transfer evenly to the substrate.
Curing Conditions: Silicone ink requires high-temperature curing (e.g., 150-180°C), while plastisol typically cures at lower temperatures.
Solutions:
Use a Dedicated Screen:
Fabricate a screen specifically for silicone ink, selecting appropriate mesh count, material, and tension.
Screen Pre-treatment:
If reusing an existing screen, consider pre-treating it (e.g., applying a corrosion-resistant coating), though effectiveness may be limited.
Testing:
Conduct small-batch testing before mass production to verify screen compatibility and printing quality.
Potential Issues with Direct Use:
Screen Blockage: The coarse mesh and material of a plastisol screen may not handle the high viscosity of silicone ink, leading to blockages and uneven printing.
Screen Damage: Silicone ink's chemical properties may corrode the plastisol screen, reducing its lifespan or causing damage.
Print Quality Issues:
Clogging of screen meshes due to high viscosity of silicone ink.
Poor adhesion or uneven transfer of ink, resulting in blurred or inconsistent patterns.
Recommended Solutions:
Use Dedicated Screens:
Fabricate screens specifically for silicone ink, selecting appropriate mesh counts, materials, and tensions.
Screen Pre-treatment:
If existing screens must be reused, consider applying a corrosion-resistant coating (though effectiveness may be limited).
Testing Validation:
Conduct small-batch trials to verify screen compatibility and printing quality before mass production.
By addressing these differences, the screen can be adapted to meet the requirements of silicone ink printing, ensuring optimal results.