Лако-красочные материалы — производство

In the wood-based panels industry a great variety of adhesives are currently is use. Condensation resins based on formaldehyde represent the biggest volume within the wood adhesives field. They are prepared by the reaction of formaldehyde with various chemicals such as urea, melamine, phenol, resorcinol, or combinations thereof. At delivery these adhesive resins are mainly liquid and consist of linear or branched oligomers and polymers in aqueous solution or dispersion. During hardening and gelling they convert to three-dimensionally crosslinked and, therefore, insoluble and nonmeltable networks. The hardening conditions used can be acidic (for aminoplastic resins), highly alkaline (for phenolic resins), or neutral to lightly alkaline (for resorcinol resins). Isocyanates [especially polymeric 4,40-diphenyl methane diisocyanate (PMDI)] are another important chemical group used for various applications in the wood industry, especially for water resistant bonds. In Table 1 are reported the main wood adhesives in use today with their main applications.