Stability of Lines with Zero Receding Contact Angle Produced by Inkjet Printing at Small Drop Volume

Area of Science:

• Physics of Fluids
• Materials Science
• Inkjet Printing Technology

Background:

• Inkjet printing enables precise deposition of liquids for various applications.
• Controlling line stability is crucial for achieving desired patterns and functionalities.
• Existing models predict stable line formation based on drop spacing and substrate properties.

Purpose of the Study:

• To experimentally determine the maximum and minimum drop spacing for stable parallel-sided liquid lines.
• To validate existing models for bounding drop spacing in inkjet printing.
• To investigate the influence of printing parameters and substrate properties on line stability.

Main Methods:

• Experimental inkjet printing with varying drop volumes (1.5 and 8.5 pL).
• Utilizing substrates with different advancing contact angles (46° and 54°) and zero receding contact angle.
• Comparing experimental results with theoretical models for drop spacing and line formation.

Main Results:

• The model for maximum drop spacing (minimum line width) generally agreed with experimental data.
• Printing speed influenced stable line width, a factor not fully captured by current models.
• A bulging instability limits the minimum drop spacing (maximum stable line width).
• A delayed bulging mechanism, possibly triggered by substrate imperfections, was observed at low temperatures with large drop volumes.

Conclusions:

• Existing models provide a good foundation for predicting inkjet-printed line stability.
• Further model refinement is needed to account for the interplay between drop volume, ejection velocity, and printing speed.
• Substrate imperfections can introduce novel instability mechanisms affecting line formation.