Exterior-grade particleboard adhesives

Wattle tannin resins are also used to manufacture other resins, such as foams comparable to phenolics, as waterproofing additives, and binders for corrugated cardboard or charcoal briquettes. This discussion, however, deals only with particleboard, plywood, glulam, and finger-jointing exterior-grade wood adhesives. Formulations of the adhesives will be mentioned ad hoc, if at all necessary, as they have already been extensively discussed in articles and reviews in the relevant literature.(7)... 

Table 1 Unfortified Tannin-Formaldehyde Adhesives Obtained by Acid-Alkali Treatment for Exterior-Grade Particleboard Example of Industrial Board Results...

Unfortified tannin-formaldehyde adhesives obtained by acid-alkaU treatment, for exterior-grade particleboard Example of indnstrial board results [11, 77, 78]... 

Pizzi A 1978 Wattle-base adhesives for exterior grade particleboards. For Prod J 28(12) 42-47... 

Structural composites can range widely in performance from high-performance materials used in the aerospace industry down to wood-based composites, which have lower performance requirements. Within the wood-based composites, performance varies from multilayered plywood and laminated lumber to low-cost particleboard. Structural wood-based composites intended for indoor use are usually made with a low-cost adhesive, which is not stable to moisture, while exterior-grade composites use a thermosetting resin that is higher in cost but stable to moisture. Performance can be improved in wood-based as well as jute and kenaf composites by using chemical modification techniques, fire retardant, and decay control chemicals, etc. 

A considerable amount of effort has gone into overcoming the sticking problems. One approach has been to manufacture a three-ply board in which the two outside layers utilize a conventional wood binder, such as a phenol-formaldehyde resin, and the internal layer is bound with an isocyanate adhesive.Deutsch Novopan GmbH of West Germany has commercialized such a process to manufacture exterior structural grade particleboard. A board prepared in this manner does not completely circumvent the potential problem of formaldehyde emissions, although they may be reduced relative to a board made solely with a formaldehyde adhesive. 

In this chapter, the development of a thermosetting adhesive from soda bagasse lignin is described. The research has concentrated on the development of interior-grade adhesives for particleboard. The local market for exterior boards is smaller than that for the interior panels, and adhesives for exterior boards are already covered by an excellent range of tannin-based adhesives. 

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