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Adhesives for wood composites G.A Ormondroyd 3.1 Introduction – A brief history of wood composites resins The development of resins and adhesives for the wood composite industry was initially driven by the need to produce composites economically and quickly and to conform to the use standards as laid down by various standards bodies Early composites such as early plywood (Muller, 1992) were produced by hand and therefore the speed of the setting of the resin was not paramount so casein resins could be used in their manufacture, whereas in today’s factories for the manufacture of medium density fibreboard, the curing time and therefore the speed at which the panels can be made is the critical point for the industry The selection of the resins will also depend on the end use of panel products Urea formaldehyde, developed in the 1930s, is a good cheap commodity resin and was suited for the development of particleboard and MDF However, as the performance criteria for the panels was increased and a requirement for panels that are suitable for moist conditions introduced, melamine was added to the resins and a more moisture resistant board was produced Phenol formaldehyde (PF) resin was originally developed in the late nineteenth century; however, it was not until the 1930s it was commercially developed and then used in the wood panel industry PF resin is used in the manufacture of plywood and engineered wood products The use of PF resins is due to its high resistance to moisture and comparative cheapness As with UF resin, the formulations have been developed to speed up production and to keep costs down; however, the basics of the resins have remained the same In recent years, the drivers for resin development have changed In the 1980s, some European countries began to regulate against the emission of formaldehyde in panel products In 1985 E1 (