Phenol formaldehyde (PF) resins are normally synthesized by reacting phenol with formaldehyde. The reaction is catalyzed either by acids or bases, leading to the formation of novolacs or resoles, respectively. Phenolic resins are found in myriad industrial products ranging from circuit boards over laminates to adhesives in wood panels. Global production volume is between 2.5 and 3.0 million tonne. As the phenol price is depending on the petroleum price (currently 2400 USD or 1800 €) there is increasing interest in replacing the fossil-derived phenol by renewable phenol from biomass [see NREL and Ensyn below as well as 1-3]. Furthermore, there are numerous research projects going on. Their results can be found on the relevant project’s home page or the partners’ websites [4-6].
Phenolic components can only be obtained from pyrolysis of lignin, a major cell wall component from lignocellulosic biomass such as wood, bark, straw etc. This has been done either by:
Recently, also hydrothermally produced bio-oil has also been used [10,11].
However, the yield of highly reactive phenol is generally very small so that research has been concentrating on using mixtures of phenolic components present in pyrolysis liquids or fractions of it. As the mixed phenolics (primarily alkylated phenol and aromatic ethers) are less reactive compared to pure phenol only a certain amount of phenol can be replaced, generally in the range of 10-40%. There are numerous issues in using biomass-derived phenolics such as low reactivity, longer curing times and smoky odor.
 Himmelblau, D.A. and Grozdits, G.A., Production of wood composite adhesives with air-blown, fluidized-bed pyrolysis oil, Forest Products Society, 1999, pp. 137-148.
 Vergopoulou-Markessini, E. and Tsiantzi, S., Enigma N. V., Neth. Antilles. Bonding resins containing modified phenolic resins, Copyright (C) 2013 American Chemical Society (ACS). All Rights Reserved., (2000).
 Nakai, T., Hata, T. and Imamura, Y., Chemical components of pyrolyzed liquid of wood-based materials and their bioactive efficiency, Wood Res., 89, 33-34 (2002).
 http://www.chimarhellas.com/wp-content/uploads/2008/07/wood-adhesives-made-with-pyrolysis-oils.PDF; last visited: 28.08.2013.
 http://www.chimarhellas.com/wp-content/uploads/2010/11/resins-from-pyrolysis-oil-to-make-wood-panels.pdf; last visited: 28.08.2013.
 http://www.forestry.gov.uk/pdf/cr_existingBioresins.pdf/$file/cr_existingBioresins.pdf; last visited: 28.08.2013.
 Sukhbaatar, B., Steele, P.H. and Kim, M.G., Use of Lignin Separated from Bio-Oil in Oriented Strand Board Binder Phenol-Formaldehyde Resins, Bioresources, 4, 789-804 (2009).
 Nowakowski, D.J., Bridgwater, A.V., Elliott, D.C., Meier, D. and de Wild, P., Lignin fast pyrolysis: Results from an international collaboration, Journal of Analytical and Applied Pyrolysis, 88, 53-72 (2010).
 Meier, D., Ante, R. and Faix, O., Catalytic hydropyrolysis of lignin – Influence of reaction conditions on the formation and composition of liquid products, Bioresource Technology, 40, 171-177 (1992).
 Cheng, S., Yuan, Z., Anderson, M., Leitch, M. and Xu, C., – Synthesis of biobased phenolic resins/adhesives with methylolated wood-derived bio-oil, – 126, – E441 (2012).
 Wang, M., Leitch, M. and Xu, C.C., Synthesis of phenolic resol resins using cornstalk-derived bio-oil produced by direct liquefaction in hot-compressed phenol-water, Journal of Industrial and Engineering Chemistry, 15, 870-875 (2009).
Giroux and Freel investigated the production and use of renewable resins derived from bark and other biomass residues using fast pyrolysis. Bark was pyrolyzed and the vapour condensed in stages. The resulting phenolic-rich fractions were used for the synthesis of resole resins with a phenol substitution level of 40%.
Freel, B., Giroux, R., and Graham, R. Ensyn Technologies Inc. Natural resin formulations, 25 Oct 2000, EP 1045890 A1.
Giroux, R., Freel, B., and Graham, R. Ensyn Group Inc. Natural resin formulations (4 Dec 2001) U.S. patent 6,326,461 B1.
Giroux R, Freel B, Graham R. Natural resin formulations. US Patent 6 555 649, Ensyn Group Inc., 29 Apr 2003.
Freel, B., Graham, R.G. and Giroux, R., Ensyn Renewables, Inc., USA . Natural resin formulations, (18 Jan 2005) U.S. patent 6,844,420 B1.
A phenolic-rich (PN) component can be extracted from bio-oil and used as a low-cost replacement for petroleum-derived phenol in phenol-formaldehyde (PF) resins. NREL has developed an extraction process to recover this PN fraction, and it has demonstrated the performance of these PN oils in modified PF wood adhesives. They have investigated how PN’s chemical reactivity and molecular architecture affected the properties of the PN-PF resin. Differences in the reactivity and the functionality of the PN, relative to trifunctional, monomeric phenol was considered during the preparation of PN-PF resins. When 25 weight percent of the monomeric phenol was replaced with PN the performance properties of properly formulated PN/PF resins compared favorably with those of commercial PF resins.
Chum, H., Diebold, J., Scahill, J., Johnson, D., Black, S., Schroeder, H. and Kreibich, R.E., Biomass pyrolysis oil feedstocks for phenolic adhesives, ACS Symp. Ser., 385, 135-151 (1989).
Kelley, S. S.; Wang, X. M.; Myers, M. D.; Johnson, D. K.; Scahill, J. W. “Use of Biomass Pyrolysis Oils for Preparation of Modified Phenol Formaldehyde Resins.” in: Developments in Thermochemical Biomass Conversion. Vol. I: 557-572. Bridgwater, A. V.; Boocock, D. G. B., eds. 1997, Blackie Academic & Professional, London.
Chum, H.; Black, S. “Process for Fractionating Fast Pyrolysis Oils, and Products Derived there from.” US. Patent No. 4,942,269, 1990.
Chum, H.; Diebold, J.; Black, S.; Kreibich, R. “Resole Resin Products Derived for Fractionated Organic and Aqueous Condensates made by Fast Pyrolysis of Biomass Materials.” U.S. Patent No. 5,235,021, 1993.
Chum, H.; Diebold, J.; Black, S.; Kreibich, R. “Phenolic Compounds Containing Neutral Fractions Extract and Products Derived there from from fractionated Fast Pyrolysis Oil.” US. Patent No. 5,223,601, 1993.
BTG Biomass Technology Group studied the application of pyrolytic lignin recovered from bio-oil in resol resins. Up to 75 wt% of phenol was substituted by pyrolytic lignin and the resin formed still met the D4 (NEN-EN 204/205) standards for this type of resin.
|Lignin/phenol/||After||curing||After curing and||boiling test|
|formaldehyde resin||Shear strength||Wood failure||Shear strength||Wood failure|
|Phenol substitution (wt%)||(N/mm2)||(%)||(N/mm2)||(%)|