1. Introduction
Urea–formaldehyde (UF) resin is the primary binder of interior-grade wood composite boards, such as particleboard, medium-density fiberboard, and plywood due to its short press time, low cost, excellent adhesion, intrinsic cohesion, high reactivity and water solubility, and lack of color in the finished product. One current challenge is to reduce or eliminate the relatively high formaldehyde emission levels of boards that arise due to the UF resin [1] and [2]. Formaldehyde is considered a priority pollutant by the United States Environmental Protection Agency [3]. Researches have been focused in reducing the emissions or exposure to formaldehyde by adding scavengers, using alternate fossil fuel based-resins without formaldehyde or by using binders based on renewable materials like those based on soy flour [4] and [5].