INFLUENCE OF HOT-PRESSING TEMPERATURE ON PROPERTIES OF ECO-FRIENDLY DRY-PROCESS FIBREBORDS WITH LIGNOSULFONATE ADHESIVE

Abstract

A major challenge for the producers of wood-based panels is to achieve formaldehyde emissions at wood levels. For that purpose, various types of lignin have emerged as particularly promising substitutes for the traditionally used urea-formaldehyde resins. Lignosulfonates are a by-product of the production of cellulose by the sulphite method. They are practically harmless to human health. The main functional groups of lignosulfonates are the hydroxyl groups and the connection with fibres is mainly through hydrogen bonds. To form these bonds, in addition to the surface with active hydroxyl groups, the temperature of hot-pressing is also essential.

This paper presents a study on the effect of hot-pressing temperature on the properties of eco-friendly dry-process fibreboards. As an adhesive was used calcium lignosulfonate in a content of 10% to absolutely dry fibres. In the experiment, the hot-pressing temperature varied from 150 to 200° C, with increments of 10° C. The main physical and mechanical properties of the panels were determined. On this basis, an analysis was made. It was found that the properties of dry-process fibreboards with only lignosulfonate as a binder are significantly affected by the temperature of hot-pressing, because of which the hot-pressing temperature should be at least 190°C.