Philippou process

Economically the Philippou process appears to be somewhat more expensive than phenol-formaldehyde. In December 1981, the cost of binder raw material for 1000 ft of HNO3 board was estimated to run 22.60, vs. 28.30 for HgOg board, and 21.00 for phenol-formaldehyde board. Further work, particularly on alternative ingredients, can change the situation (103),... 

Procedures bearing some similarity to the Philippou process were patented by Emerson in 1953 and 1963 104, 105). The first patent consisted of pretreatment of lignocellulosic particulate material with urea (0.7-11%), followed by addition of furfural (0.8-16%) and an acid or acid salt catalyst (1.0-16%), and pressing at elevated temperatures. The second involved a mixture of urea, furfural, lignin, petroleum resin, drying oil, wax, and an oxidation catalyst as a cross-linking mixture. 

The situation is simpler with wood preactivated in a separate step (S3, S5), although in this case a question might be raised whether changes on the wood surface (e.g., formation of carboxyls) merely catalyze cross-linking of the polymer or whether covalent bonds form involving surface. Not much experimentation has been done so far aimed at elucidation of the mechanisms of nonconventional bonding methods involving intermediacy of a polymer. Most of the available evidence is restricted to the Philippou process. 

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