Temperature Control for Flexographic Inks

In recent years printers have found that temperature control of their process is crucial in contributing to consistent print quality and ink and solvent cost savings. Temperature control is critically important for flexographic inks due to its significant impact on ink viscosity, drying speed, print quality, and press performance. Here is a breakdown of why controlling temperature matters in flexographic printing:

Ink Viscosity and Temperature Relationship

Ink Viscosity is temperature-dependent: As temperature increases, ink becomes less viscous (thinner); as it decreases, ink thickens. However, as ink temperature increases, solvents and amines will evaporate at a faster rate resulting in ink viscosity to increase despite the high ink temperature.

Impact of Poor Ink Viscosity

If ink is too thin, it can cause ink slinging, poor ink transfer, dot gain, and smudging. If ink is too thick, it can lead to poor coverage, skipping, or clogging anilox cells. Both high and low viscosity will cause print quality issues.

Constant process temperature and viscosity control = consistent process viscosity, which is key to repeatable, high-quality prints.

Drying Time and Evaporation Rate Control

Solvent-based and water-based inks are sensitive to temperature changes, which affect evaporation rates.

Elevated temperatures speed up drying but can cause:

• Premature drying on the press (especially in the anilox or plate), leading to downtime for cleaning
• Increased solvent loss and emissions

Low temperatures slow ink drying, risk smearing, blocking, or setoff.

Maintaining Color Consistency

Temperature fluctuations can cause color shifts due to:

• Viscosity changes affect pigment dispersion
• Ink layer thickness variations

This is especially critical for process color (CMYK) printing, where slight inconsistencies can disrupt color balance.

Press Performance and Efficiency 

Stable ink temperature ensures fewer press and ink viscosity adjustments, reduced solvent/amine evaporation, less downtime due to cleaning or print quality related issues, and more efficient runs.

Reduces the need for frequent viscosity checks and corrections.

Ink Stability and Shelf Life

Prolonged exposure to hot temperatures can degrade certain ink components, including resins and pigments.

Controlled temperatures during storage and on-press maintain the integrity and performance of the ink.

Best Practices for Temperature Control

• Use inline ink viscosity and temperature control systems which include Temperature control units (TCU), plant chilled water and a process viscosity control system to control solvent/amine evaporation
• Store all inks in temperature-controlled environments
• Monitor ink and pressroom temperatures regularly

Maintaining proper temperature control is an essential aspect of process control in flexographic printing, directly influencing print quality, waste reduction, and operational efficiency.

Conclusion

For more information, please contact INKSPEC.  Sales@inkspec.com  +14504415005  www.inkspec.com