Ultrasonic welding of folding boxboards

Abstract

Today’s environmental concerns are pressuring industries to substitute paper-based materials in place of plastics in many sectors including packaging. However, assembling papers and paperboards using environmentally friendly solutions remains a technological challenge. In this context, ultrasonic (US) welding is an alternative to adhesives. In this work, the potential of US welding to assemble folding boxboards was investigated. Folding boxboards are commonly coated to enhance printability. This coating is generally composed of mineral pigments (85 to 90%) and polymer binders (10 to 12%). This study evaluated whether the presence of the coating layer allows the assembly of paperboards by US welding. Results indicated that welding coated folding boxboards is possible provided that coating weight and binder content are high enough. The mechanical performances of the welded boards met the requirements of most packaging applications. Adhesion in the welded joint resulted from a combination of thermoplastic (melting and flowing of the binder) and thermoset (degradation reactions) effects. However, it was not possible to assemble coated folding boxboards without degrading the welding zone. While the materials and process need to be optimized, this work represents a big step forward toward the adhesive-free assembling of paper-based materials.

Ultrasonic welding of poly(vinyl alcohol) coated-papers hydrophobized by chromatogeny grafting

“…In this context, the main concern of the present study is to investigate on the ultrasonic (US) welding as a potential processing method to assemble papers coated with PVOH and grafted by chromatogeny. US welding has recently emerged as a possible solution to manufacture bio-based materials (Regazzi et al 2019a;Teil et al 2021) and to assemble papers and paperboards (Regazzi et al 2019b;Monot et al 2021;Charlier et al 2021). US welding is a processing method which consist in applying high-frequency acoustic vibrations (20 to 40 kHz) under pressure (Tolunay et al 1983;Benatar et al 1989).…”

“…More recently, Teil et al and Regazzi et al manufactured and characterized biocomposites made of native starch granules and wood fibers and obtained by ultrasonic compression molding (Regazzi et al 2019a;Teil et al 2021). Only a few recent studies, done by the same team of authors, discuss the use US welding to assemble paper-like materials (Regazzi et al 2019b;Monot et al 2021;Charlier et al 2021). While working with 100% lignocellulosic papers, Regazzi et al showed that papers can be welded only for high lignin and hemicelluloses contents in the paper pulp (Regazzi et al 2019b).…”

“…Thus, it seems that the coating layer is the main component involved in the development of adhesion at the welding interface. Based on these findings, Monot et al also investigated on the US welding of folding boxboards (FBB) (Monot et al 2021). The authors studied the influence of the composition of the coating formulation (deposited for printability purposes) on the weldability.…”