Abstract

Abstract
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
substrate via thermal activation provided by a 27W CO
2 laser is discussed in this work.
The results gathered for this work have been used to generate a novel empirical tool that
predicts the CO
2 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 CO
2
laser spot increases with respect to spot diameter, simultaneously yielding greater bond
stability in the face of short-term laser variance.