The Role of Surface Tension in Inkjet Printing
Surface tension is a key physical property of ink that directly influences droplet formation, print consistency, and adhesion to various materials. Whether you’re using CIJ, TIJ, DOD, or high-resolution piezo systems, understanding and managing surface tension helps ensure sharp codes and minimal waste.
What Is Surface Tension?
Surface tension is the force that acts on the surface of a liquid, causing it to contract and form spherical shapes. It is measured in milliNewtons per meter (mN/m). In inkjet printing, surface tension determines how easily an ink forms droplets and how those droplets behave when they contact a substrate.
How Surface Tension Affects Inkjet Printing
1. Droplet Formation and Stability
Ink with the right surface tension forms clean, uniform droplets. If tension is too high, the ink may not jet properly or may form large, uncontrollable drops. If too low, the ink may mist or break into satellites.
2. Adhesion to Substrate
When a droplet hits the substrate, surface tension competes with the substrate’s surface energy. This determines how much the ink spreads. Proper balance is needed to avoid either poor adhesion (high tension) or bleeding (low tension).
3. Print Resolution and Sharpness
Surface tension affects how tightly a droplet holds together. High tension = sharper edges but poorer spreading; low tension = better coverage but risk of blur.
4. Wetting Behavior and Contact Angle
Contact angle is the angle between the droplet edge and the surface. A lower contact angle = better wetting. For non-porous surfaces like plastic or metal, surface tension must match the material to avoid “beading” (droplets not spreading).
Typical Surface Tension Values in Inkjet Printing
| Ink Type | Typical Surface Tension (mN/m) |
|---|---|
| CIJ Solvent-Based Inks | 24–32 |
| TIJ Water-Based Inks | 35–45 |
| UV Inks | 20–30 |
| Pigmented Inks | 28–38 |
Matching Ink to Substrate
- Plastic (PE, PP): Use low-tension solvent or UV inks with adhesion promoters
- Glass: Needs medium-low tension with high surface energy adjustment
- Paper: High surface tension inks work well due to absorption
- Foils or coated films: Require fine tuning to prevent ink lift or smudge
How to Adjust Surface Tension
- Add surfactants to reduce surface tension (done at ink formulation stage)
- Use substrate pre-treatment (e.g. corona or plasma) to increase surface energy
- Select ink type designed for your material and printer technology
FAQs
- Can I measure surface tension in-house? Yes. Use a tensiometer or contact angle goniometer, or test ink pens for surface energy matching.
- What happens if surface tension is wrong? You may get splashes, gaps, misalignment, or unreadable codes. Always test before large runs.
Conclusion
Surface tension plays a central role in inkjet performance—from drop formation to substrate interaction. Managing it through ink formulation and substrate selection ensures clear, durable, and consistent codes. For help matching surface tension to your printing needs, contact Cheef Inkjet at sales@cheef.cn.
