Monitoring of the application of laminating adhesives to polyurethane foam by near infrared chemical imaging

Abstract

Near infrared chemical imaging was used for the quantitative determination of the application weight of hot-melt adhesive layers laminated to polyetherbased polyurethane (PUR) foam as well as for monitoring of its spatial distribution across the surface of the foam. Adhesive layers were applied as melt-spun fibrous webs of a thermoplastic polyester with application weights between about 20 g m -2 and 130 g m -2 . In spite of the coarsely porous surface structure of the foam, RMSEP was found to be 3.8 g m -2 only. Chemical images of the adhesive layers revealed that a minimum of two adhesive webs corresponding to an application weight of about 40 g m -2 are required for the formation of a continuous layer without holes. Average application weights derived from the chemical images have shown an excellent correlation with gravimetric reference values.