**1. Introduction**

Engineered wood products are building materials that are made by laminating layers of wood together or by binding wood fibers together into a composite material, typically with an adhesive usually involving heat and/or pressure [1]. Engineered wood products offer consistency of structural performance and dimensional stability, making it possible to integrate them successfully with other construction materials on large and complex projects [2]. Engineered wood products are making it conceivable to build taller and bigger wood structures, which is highly asked by the building market [3]. There are many different types of engineered wood products, which can be categorized according to the type of feedstock used in their manufacture. The engineered wood association offer guidance on the properties and applications of engineered wood products being classified in three primary categories, as shown in **Figure 1**. Advantages of using engineered wood products compared to alternative

**Figure 1.** *The classification of engineered wood products, according to APA.*

building materials are: (i) natural, renewable, sustainable and reduced carbon footprint; (ii) lighter-weight and greater flexibility in design and construction; (iii) faster and quitter construction; (iv) cheaper construction, warmth and esthetically pleasing with health benefits. Engineered wood products are considered to be renewable construction materials due to their composition [2].

A major factor supporting growth in the use of engineered wood products in construction is the increased environmental and sustainability concern [3, 4], which is influencing construction techniques and the choice of building materials. As such, wood is a renewable and sustainable building material used for modern engineering solutions and functional and decorative applications [5]. Wood has better insulating properties and a positive carbon balance compared to other building materials. Wood has much smaller carbon footprint than other construction materials, and increased use may reduce CO2 emissions by 14% [6]. Moreover, the greenhouse gas emissions have been shown to be as the same level as of concrete and lower than steel [7]. If properly maintained, wood can storage carbon for long lifespan. The engineered wood products used in exterior applications are maintained in time due to the use of preservatives such as creosote, halogenated carbamates, benzothiazoles, pentachlorophenol, (alkyl) imidazoles, bis(tributyltin) oxide, or salt-based impregnates [8, 9]. In addition, fire retardancy is an important behavior if the engineered wood products that are used in construction applications. Currently, the halogenated products are used as fire retardant additives for wood applications [10–13].

Both the currently used preservatives and halogenated fire-retardant additives used today are considered toxic, both for humans and environment. Preservative leaching problem when wood is encountering water and recyclability of wood materials when preservatives are used have been discussed by several authors [14–16]. As such, these concerns contribute to the necessity of developing non-toxic bio-based alternatives. Issues of sustainability and carbon sequestration opens the possibility for new green

#### *Biopolymers as Coating Additives for Engineered Wood Products DOI: http://dx.doi.org/10.5772/intechopen.113049*

technologies which can improve durability, stability, and performance of wood, especially in exterior applications [17]. The wood preservative industry is interested in finding low-cost, environmentally friendly methods for the treatment of the wood [18]. Engineered wood products (EWP) producers recognize the potential to greatly expand their market-share if more optimal and affordable wood protection options can be found [1].

Extending the service life of wood and wood-derived products by using environmentally friendly biopolymers represents an attractive approach for wood protection from the perspectives of human health and environmental protection [19, 20]. The modern coating market is dominated by acrylic, polyurethane, and polyester polymer resins produced from unsustainable fossil resources. These coating additives are still used on the market due to their properties and low price. In the recent years, sustainable solutions such as vegetable-oil based coatings such as tall linseed, coconut, soybean, and castor-oil have been introduced on the market [21, 22] These oils are often used in different coating combinations to improve their properties. Usually, most of the additives used in coating applications requires chemical modification [21–24].

An environmentally friendly solution for wood preservation could be the use of biopolymers [25]. Biopolymers, due to the compatibility with the main wood components are considered as interesting alternatives to be used in coating applications [20]. Biopolymers not only that can enhance the performance of adhesives derived from petroleum in different ways [26], but also they can be used to develop environmental friendly and sustainable bio-based alternatives. Biopolymers are categorized as a function of their monomer unit in polysaccharides (cellulose, hemicellulose, glucans, starch), proteins (gelatin, casein), derived polypeptides (collagen, peptides) and polyphenols (tannins, lignin) [25, 27]. Biopolymer-based coatings can be directly deposited onto the substrate surface or by chemical reactions between the biopolymer and the substrate. The chosen coating technique is decided by a specific application, thus depending on several factors, described by Song et al. [28]. Biopolymers, due to the superior compatibility with the main components of wood, have a positive effect on the penetrability of biopolymer into the wooden mass and can enhance the biopolymer biocidal activity. Many other benefits, such as wood recyclability have been pointed out in the work of Patachia and Croitoru [29]. As such, this book chapter is important as it gives an overview on the use of biopolymers in coatings formulations and how these formulations can protect the wood against fire, insects, mold and water. Using natural biopolymers to replace the conventional preservatives and fire-retardant additives in wood protection is highly recommended, as the engineered wood product will be completely renewable and recyclable.
