Additives in Wood Products—Today and Future Development

Abstract

Most wood products include additives. They may be preservatives to protect the wood against biological degradation or against fire, coatings for protection or to give the wood a more favourable aesthetic appearance, non-wood materials to improve the performance of the product and overcome weaknesses in the wood material, or plastics in combinations with wood residues to create new types of wood-plastic combinations. The global wood industry is, for example the largest user of adhesives; about 80 % of all wood and wood-based products involve some form of bonding and 70 % of the total volume of adhesives produced is consumed in the woodworking industry. Wood can thus be regarded as a composite consisting of wood-based materials combined with other materials to form an aggregate material. An example is plywood, in which veneers are joined with adhesive to form a flat panel. Other types of wood composites include various board products, structural composite timber and, furniture and joinery components, all including some form of bonding with adhesive. This situation obviously influences the way in which we should relate to wood products and their environmental impacts. This chapter gives a state-of-the-art presentation of different additives currently being used in wood products. This information is necessary for further studies on the influence that these additives have on the service life and on environmental aspects, and the limitations which they may impose on the reuse, recycling and upgrading of wood products.

Innovative Wood Surface Treatments Based on Nanotechnology

“…With this approach, a thin homogeneous film of water is created, which can run off the surface and dry. This is advantageous, since no residual contamination is left on the surface [6].…”

“…This means that they can protect the substrate as well as the surface of the treated material, and should possess an attractive color and retains a natural appearance. The basic properties of a coating are determined by its main components, namely binders, pigments, solvents, fillers, and additives [6]. The binder sticks pigment particles to the wood surface and to each other, creating a protective layer.…”

“…Additives prevent mold and decay, make the color drip-free, help the drying procedure, improve the adhesion characteristics, and control finishing. Coatings which are currently applied to wood surfaces can be categorized as air-drying, reaction-curing, water-soluble, stains, and oils and waxes [6][7][8].…”

Advances in Wood Composites

“…The majority of wood composites in their final use, contain additives. These may include protective coatings, coatings to improve its aesthetic appearance, preservatives for protection against fire or biological factors like fungi and insects, and even plastics to successfully create new types of products [29]. When wood is used in outdoor applications, its surface is very much exposed to many agents and its protection is an imperative need.…”

“…Its protection therefore can be achieved with an efficient manner, which includes coating, this can be done with surface or bulk treatment. Coatings, which are currently applied to wood surface can be categorized as air-drying coatings, reaction-curing coatings, water-soluble coatings, stains, and oils and waxes [16,29]. A fast water-based ultraviolet light (UV) curing polyurethane-acrylate (PUA) wood coating was prepared and applied on oak (Quercus alba L.) at different coating amounts [30].…”