Loop Tack Failure in PET Labels: Prevention Tips for Long-Term Adhesion

Introduction

Labeling failures often begin with a simple issue: PET film not sticking as expected. Over time, this minor annoyance can become a major production bottleneck or even lead to costly product recalls. Many of these issues trace back to loop tack failure causes, including improper handling, poor adhesive design, and environmental exposure. This final article provides proactive strategies to prevent tack failures before they start—based on expert adhesive PET troubleshooting techniques.

1. Start with a Comprehensive Adhesive Design Process

Not all adhesives are created equal. The success of loop tack depends on careful consideration of:

• Substrate type
• Environmental exposure (temperature, humidity, chemicals)
• Label shape and application speed

A robust formulation prevents many loop tack failure causes.

✅ Best Practice: Partner with chemical engineers or suppliers early in the design phase to create a tailored PET adhesive formula.

2. Conduct Loop Tack Testing on All Incoming Rolls

Inconsistent batches are a hidden threat. Visual inspection alone won’t catch adhesive degradation.

✅ Use ASTM D6195 or similar loop tack testing equipment to validate adhesion before using new material.

• Log all results to establish performance benchmarks.
• Reject rolls that fall below minimum tack force.

3. Train Operators on Surface Cleanliness and Pressure Application

Human error can be a hidden reason your PET film is not sticking.

• Labels applied without enough pressure may lift later.
• Dust or oil from handling contaminates critical bonding areas.

✅ Provide standardized training and visual work instructions.

4. Store Labels in a Controlled Environment

Humidity and heat are leading contributors to adhesive PET troubleshooting challenges.

• Softening, oxidation, and hardening of adhesive are all possible under poor storage conditions.

✅ Store labels in:

• 15°C–25°C temperature range
• 40%–60% relative humidity
• Original packaging until ready to use

5. Use High-Energy Surfaces or Surface Treatment Methods

Low-energy substrates often result in PET film not sticking well on contact.

✅ Solutions include:

• Pre-treatment using corona, flame, or plasma
• Applying a bonding primer
• Switching to rubber-based or hybrid adhesives

6. Use Release Liners Compatible with Long-Term Tack

Incorrect liners can reduce the adhesive’s surface availability or leach chemicals into the adhesive layer.

✅ Use liners tested for chemical inertness and compatibility with the PSA layer over extended storage.