It is usually not recommended to use the same screen for printing with silicone and glue (such as plastisol) because there are significant differences between the two in material properties, printing process requirements and performance. The specific analysis is as follows:
1. Differences in material properties lead to incompatible printing parameters
Silicone
Viscosity and curing method: Silicone has a high viscosity and needs to be cured by heating (such as 150-200℃) or vulcanization at room temperature to form an elastomer after curing.
Control of glue output: A low-mesh screen (such as 80-120 mesh) is required to control the glue output to avoid blurring the pattern or clogging the mesh.
Difficulty of cleaning: Residues after curing are easy to clog the screen, requiring special cleaning agents and frequent maintenance.
Glue (plastic sol)
Fluidity and drying method: The glue has low viscosity and strong fluidity. It is cured by natural drying or low-temperature drying, and the residue is easier to clean.
Fineness requirements: A high-mesh screen (such as 150-200 mesh) is required to achieve fine patterns. A low-mesh screen may cause bleeding or unclear edges.
Chemical stability: The requirements for screen material are relatively low, but it is necessary to avoid mixing with silicone residues to cause pollution.
2. Printing process conflicts affect effects and efficiency
Screen mesh conflict
Silicone requires a low-mesh screen to control the amount of glue, while glue requires a high-mesh screen to ensure fineness. The same screen cannot meet the needs of both at the same time, which is easy to cause printing defects (such as silicone blocking high-mesh screens and glue bleeding through low-mesh screens).
Curing process differences
Silicone needs to be heated or vulcanized for curing, and heat or chemicals may be released during the process, and residues are easy to clog the screen; glue is cured by natural drying or low-temperature drying, and the residue is easier to clean. Sharing screens may cause cross-contamination and affect printing quality.
Different printing effect requirements
Silicone printing pursues three-dimensionality, thickness and elasticity, and requires thick printing or multiple superposition; glue printing focuses on color reproduction, fineness and coverage, and requires stable screen tension and uniform opening. It is difficult to optimize both effects at the same time with the same screen.
3. Temporary solutions in special circumstances
If the requirements for pattern accuracy and three-dimensional sense are not high, and certain defects (such as edge burrs and uneven thickness) can be accepted, the following measures can be tried:
Use a universal screen: such as medium mesh (120-150 mesh), high-tension polyester screen, and adjust the viscosity of silicone and glue (such as diluting glue and thickening silicone) to adapt to the same screen parameters.
Strict cleaning process: use scrapers and cleaning tanks of different colors to avoid material mixing; regularly check the screen status (such as tension and opening rate).
Step-by-step printing process: print different materials on the same screen in stages (such as printing silicone first, printing glue after cleaning), but ensure that the screen material is resistant to the cleaning agents of the two materials (such as solvent resistance, acid and alkali resistance).