The Effect of Laser Power, Traverse Velocity and Spot Size on the Peel Resistance of a Polypropylene/Adhesive Bond

• Published in: Packaging technology & science 2015-07, Vol.28 (7), p.621-632
• Main Authors: Dowding, C., Dowding, R., Franceschini, F., Griffiths, J.
• Format: Article
• Language: English
• Subjects: Adhesive bonding; bond; Bonding; Carbon dioxide lasers; laser; Lasers; non-contact; Packaging; peel-seal; Polypropylenes; scanning; Spots
• ISSN: 0894-3214; 1099-1522
• DOI: 10.1002/pts.2128

The mean peel resistance force achieved with respect to variation in the laser power, incident spot traverse velocity and incident spot diameter between linear low density polyethylene film backed by a thin commercial adhesive coating that were bonded to a polypropylene (PP) substrate via thermal activation provided by a 27W CO2 laser is discussed in this work.The results gathered for this work have been used to generate a novel empirical tool that predicts the CO2 laser power required to achieve a viable adhesive bond for this material combination. This predictive tool will enable the packaging industry to achieve markedly increased financial yield, process efficiency, reduced material waste and process flexibility.A laser spot size‐dependent linear increase in laser line energy was necessary for this material combination, suggesting the minimal impact of thermal strain rate. Moreover, a high level of repeatability around this threshold laser line energy was indicated, suggesting that laser‐activated adhesive bonding of such polymer films is viable.The adhesion between the material combination trialled here responded linearly to thermal load. In particular, when using the smallest diameter laser spot, it is proposed that the resulting high irradiance caused film or adhesive material damage, thus resulting in reduced peel resistance force.The experimental work conducted indicated that the processing window of an incident CO2 laser spot increases with respect to spot diameter, simultaneously yielding greater bond stability in the face of short‐term laser variance. © 2015 The Authors. Packaging Technology and Science published by John Wiley & Sons Ltd. This work conducts empirical analysis of the polymer packaging seal‐peel resistance response to three laser variables: power, incident traverse velocity and incident spot diameter. Analysis of these relationships has yielded an empirical relation that has been used to generate a predictive tool for users to establish operating windows given known process requirements. This work details an experimental approach that is of use for all polymer material combinations.