Peel resistance characterization of localized polymer film bonding via thin film adhesive thermally activated by scanned CO2 laser

Thermal laser polymer bonding is a non-contact process for the joining of polymer laminates using thermally activated adhesives. Conventional, contact based bonding techniques suffer from mechanical wear, geometric inflexibility and poor energy efficiency. The application of lasers offers the potential for highly localized delivery of energy and increased process flexibility whilst achieving controlled and repeatable bonding of polymer laminates in a contact free process. Unlike previously reported techniques, here it is reported that laser based non-contact bonding is both viable and highly desirable due to the increased levels of control it affords the user.In this work, laser polymer bonding of 75 μm thick linear low density polyethylene (LLDPE) film backed with a thermally activated adhesive to a 640 μm thick polypropylene (PP) substrate was conducted using continuous wave 10.6 μm laser radiation and scanning galvanometric optics. The effect of laser power and scanning traverse speed on the peel resistance properties of the bonded polymer laminates is presented, with a threshold specific energy density for successful adhesive activation determined.

► Incident energy density of 0.075 J/mm2 is required for peel–seal response.
► Above this the adhesive bond strength achieved was proportional to laser power.
► A second threshold of 0.094 J/mm2 instigates a polymer welding response.
► Polymer welding yields a permanent tear seal bond between polymer layers.
► Demonstrates viability and desirability of the novel process to a valuable industry.