A new methodology to evaluate the cure of resin-impregnated papers for HPL

Abstract

High-pressure laminates (HPL) are a multipurpose, high strength and value-added surface material foruse on construction (facades, walls and flooring) and furniture sector. Standard HPL is obtained by thehot-pressing of an assembly of paper sheets impregnated with thermosetting resins (usually melamineformaldehydeand phenol-formaldehyde) and normally is used for surfacing wood based panels (WBP).In the last years the production of HPL has increased and new products are being launch, such as: HPLproduced with new resins, HPL with new functionalities (chemical resistance, wear resistance, UVresistance, etc.), compact HPL (high thickness).The introduction of new resins and the incorporation of additives increase the interest on thedevelopment of a novel methodology to evaluate the cure of the resin-impregnated paper makingpossible to optimise both the impregnation (resin content, speed, temperature) and the hot-pressing(time, temperature, pressure schedule) stages.Using ABES (Automated Bonding Evaluation System) equipment, a study on the curing conditions ofseveral resin-impregnated papers and its impact on the performance of HPL, has been carried out. Anew methodology is presented and applied to several different combinations of kraft, decorative andoverlay papers and wood, selected to ensure higher fidelity to a real HPL under hot-pressing conditions.A kinetic model for the cure of impregnated papers was developed and its relation with currentaccepted curing mechanism is presented.