Adhesives and coatings from phenol-formaldehyde/resorcinol-formaldehyde resins

Resale phenal-formaldehyde resins were prepared and modified with the prepared resorcinol-formaldehyde resins. The optimum conditions of formulation and curing processes were studied to obtain modified wood adhesives characterized by high-tensile shear strength values. This study indicated that the more suitable conditions are equal weight ratios of phenol-formaldehyde to resorcinol-formaldehyde resins in the presence of paraformaldehyde (20 or 15wt%) of the resin content as a curing agent at 80 or 25 degrees C for 40 min or 100-110 days, respectively. The activation energies of the curing reactions for phenol-formaldehyde/resorcinol-formaldehyde resin samples were determined. Metallic and glass coatings from the previous pure resins and their formulated cured mixtures were prepared and evaluated as varnishes or paints. (C) 1998 John Wiley & Sons, Ltd.