Case Study: Water-Based Flexographic Ink for Diaper BOPP Film Printing

In the baby care industry, packaging safety, odor control, and environmental compliance are critical evaluation criteria for both brand owners and packaging converters. Printed BOPP films are widely used for diaper outer packaging and decorative layers, making ink performance a key factor in overall product quality.

This case study presents the application of Starcolor water-based flexographic ink in diaper BOPP film printing, focusing on measurable improvements in safety, adhesion performance, and production stability.

Industry Background: Quantifiable Requirements for Diaper Packaging Inks

BOPP (Biaxially Oriented Polypropylene) film is the preferred substrate for diaper packaging due to its mechanical strength, moisture resistance, and printability. However, its relatively low surface energy presents challenges for water-based ink systems.

For diaper packaging, printing inks are typically required to meet the following benchmarks:

• Low odor after drying, suitable for enclosed baby care products
• Reduced VOC emissions compared with conventional systems
• Stable adhesion on corona-treated BOPP film (≥38 dyn/cm)
• Consistent performance at flexographic printing speeds of 150–200 m/min

As sustainability standards increase globally, water-based flexographic inks have become a practical solution rather than an experimental alternative.

Customer Challenges: Measurable Issues in Previous Production

A diaper packaging printing partner experienced several production-level challenges during earlier ink trials:

• Inconsistent adhesion results in cross-hatch tape tests on BOPP film
• Noticeable residual odor in finished rolls after printing and rewinding
• Frequent plate cleaning required during long print runs
• Increased waste during start-up and color stabilization stages

These issues directly affected production efficiency, quality consistency, and approval from brand quality control teams.

Starcolor Solution: Data-Oriented Water-Based Flexographic Ink System

Starcolor supplied a high-adhesion water-based flexographic ink engineered specifically for BOPP film used in diaper packaging. The solution was evaluated under real production conditions.

Low Odor and Environmental Performance

Compared with the customer’s previous ink system, Starcolor water-based ink delivered clear environmental benefits:

• Noticeable odor reduction after drying and rewinding
• VOC emissions significantly lower than conventional solvent-based references
• Improved working environment on the pressroom floor

These improvements supported smoother brand audits and internal safety assessments.

Adhesion Performance on BOPP Film

On corona-treated BOPP film, Starcolor water-based ink demonstrated:

• Stable adhesion results in standard cross-hatch and tape tests
• No visible flaking or ink transfer during rewinding
• Reliable resistance during bag-making and downstream converting

This level of adhesion consistency reduced rework and quality-related complaints.

Production Stability at Industrial Printing Speeds

During continuous production, the ink system was operated at printing speeds between 150 and 200 m/min:

• Balanced drying behavior reduced plate contamination
• Plate cleaning frequency decreased during long runs
• Color density and image sharpness remained consistent

Overall press uptime improved, contributing to more predictable production planning.

Results: Practical Improvements Observed in Production

After full implementation, the printer reported the following operational benefits:

• Lower odor perception in finished diaper packaging
• More consistent adhesion across different print batches
• Reduced start-up waste and fewer unplanned stoppages
• Successful approval by brand owners and end customers

The solution proved scalable and suitable for long-term diaper packaging production.

Conclusion: Data-Supported Water-Based Ink for Diaper Packaging

For diaper BOPP film printing, ink performance must be evaluated not only on sustainability claims, but also on measurable production results.

Starcolor water-based flexographic ink demonstrates that environmental responsibility, strong adhesion, and high-speed printability can be achieved simultaneously, making it a reliable choice for modern baby care packaging.