Preparation of binders from inexpensive by-products for use in high-pressure phenolic laminates - IV. Reactive phenosolvan pitch-lignin and phenosolvan pitch resol derived products for use in impregnating varnishes and testing of 10-ply paper laminates

Equal mixtures of phenosolvan pitch and autohydrolysis bagasse lignin in th e presence of either acid or alkaline catalyst and without catalyst were su bmitted to a thermal treatment stage at 230 degrees (phenolation). Each of the phenolated products was blended with phenol resol (50:50 ratio) for imp regnation of kraft paper and assembly of 10-ply high pressure laminates. Ev aluation of their physical performance indicated that these systems possess ed high strength and stiffness. In this regard, the acid system behaved som ewhat better than the alkaline phenolated system, which in turn was better than the system without catalyst. These gains were however accompanied by a general loss in material toughness. These findings were similar to those o btained with a mixture of phenol- and pitch resol and substantiated the use of either "modified pitch" via a formaldehyde pre-polymer stage or "modifi ed pitch-lignin" via heat treatment (phenolation) as "reactive extenders" f or phenol impregnating varnish.