Performance of pyrolysis oil-based wood adhesives in OSB

Wood adhesives derived from softwood bark residues pyrolysis oil have been developed for oriented strandboard. (OSB), an exterior grade wood composite product. The phenolic-rich oil produced by the vacuum pyrolysis Pyrocycling(TM) process was used to replace part (25% and 35% by weight) of the phenol in phenol-formaldehyde (PF) resin formulations. Some parameters, e.g., F/P and NaOH/P molar ratios) have been investigated in the development of the new type of adhesive. These preliminary results showed that under commercial board manufacturing conditions (e.g., 2.5 wt.% resin content, ovendry wood basis; 3.0 min. pressing time for 11.1-mm-thick board), the mechanical properties (modulus of rupture, modulus of elasticity, and internal bond) and thickness swelling of homogeneous and 3-layer boards bonded with these types of resin (25% and 35% phenol replacement) exceeded the minimum requirements set by CSA0437 Series 93, both in dry and wet (2-hr. boil) tests. It is concluded with the present work, that pyrolysis oil can replace up to 35 percent of phenol in PF surface resin formulation for OSB (11.1-mm-thick, 3-layer boards). Higher replacement of phenol with the oil is being worked on. Post-treatment (2 hr. at 150degreesC in the oven) significantly improved the internal bond strength and thickness swelling of the boards.