Optimization of application of natural rubber based API adhesive for the production of laminated wood

Abstract

The use of natural rubber latex (NRL) for wood adhesive has been identified since a long time ago, even though its adhesion quality is fair. Some modifications of the NRL, as well as the blending of NRL with other commercial wood adhesives, have already been reported. Another potential use of NRL in the wood adhesive formulation is a base polymer of isocyanate type adhesive, which is called aqueous polymer isocyanate (API) adhesive. This study aimed to optimize the aqueous polymer isocyanate (API) type adhesive made from natural rubber latex (NRL) using response surface methodology (RSM). Central composite design (CCD) was used for the RSM. Three factors have been optimized, namely the percentage of crosslinker (7.3-20.7% of the weight of base polymer), glue spread rate (112-298 g/m2), and pressing time (2-22 hours). Results of the study showed that the model generated from the optimization was fit and could be used to predict the relationship between the three factors and the bonding strength. Optimum conditions for the adhesive application for the production of laminated wood used 16.4% crosslinker, glue spread rate of 298 g/m2 with a pressing time of 6 hours. Using these conditions, the shear strength of the laminated wood obtained was 8.8 MPa.