Purpose The purpose of this work was to develop a new trispiperazido phosphate-based reactive diluent (diphosphate-piperazine hydroxyl acrylate [DPHA]) and used as a flame retardant with an epoxy acrylate (EA) in ultraviolet (UV)-curable wood coating. Design/methodology/approach The concentration of reactive diluent was varied from 0% to 20% in the UV-curable formulation with constant photoinitiator concentration. The effect of DPHA concentration on film properties was studied by differential scanning calorimetry and thermogravimetric analysis, gel content, water absorption and limiting oxygen index. Findings The results showed that the viscosity of the prepared formulation decreased by increasing reactive diluent (DPHA) concentration which leads to improving the coating efficiency. A high concentration of reactive diluent (DPHA) of the cured films shows good resistance against stain, mechanical and thermal properties, which results in an increased glass transition temperature (Tg) and cross-linking density of the films. Originality/value The new trispiperazido phosphate-based reactive diluent was used in wood coating formulation, which resulted in excellent flame-retardant properties with higher cross-linked density with good stain resistance. This material can provide a wide range of application for coating industries to produce a glossy finish.

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Flame retardants mitigate the threat of fire from inherently flammable wood and wood products responsible for sustaining a high standard of living. Wood is one of the aesthetically pleasing, highly sustainable as well as eco-friendly materials. It is not only an integral part of structures, but also the main source of home appliances, furniture, industrial applications, and offices all over the world. The coating provides protection to wood materials against outdoor weathering, photochemical degradation, and fire. Therefore, to minimize the degradation of wood for the increasing long life and survival ability, various coatings were synthesized and applied to enhance their performance for the wood application. This review provides a historical overview that leads to the structural properties of wood and the most promising surface treatments that will help pave the way for developing more effective and non-intrusive flame retardants in the future.

A novel melamine-phosphate tri-functional acrylate (MPTO) was successfully synthesized via cyclization reaction of hexamethylolmelamine (HMM) with phosphorous oxychloride (POCl3) followed by addition reaction of hydroxyethylmethacrylate (HEMA). The molecular structure of MPTO was identified by FTIR and 1H-NMR, 13C-NMR, and GC-MS spectra. The synthesized MPTO oligomer was impregnated with polyurethane acrylate to make various formulations and UV cured on wood and galvanized steel panels. The results of UV cured films from differential scanning calorimeter (DSC) and thermo-gravimetric analysis (TGA) exhibited increase in thermal stability and highest char yield of 18.4% at 800°C. The diffused diffraction peak appearing around 2ϴ = 16–22° corresponds to an amorphous structure which leads to irregular arrangement with formation of strong cross-linking polymer network. Furthermore, all coating films show prominent flame retardancy with UL-94 V-0 rating and maximum limiting index (LOI) values of 34.8%. The polyurethane acrylate (PU) coatings cured with MPTO that exhibited excellent mechanical properties were estimated using various tests such as adhesion, pencil hardness, solvent resistance, flexibility, and corrosion test. The coating performance revealed that MPTO can improve the mechanical, thermal, and flame retardant properties because of its unique structure identity of melamine-phosphate moiety and long aliphatic segment of an acrylate ester.

A novel melamine-phosphate trifunctional acrylate MPTO) was successfully synthesized via simple cyclization of hexamethylolmelamine (HMM) with phosphorous oxychloride (POCl3) followed by addition reaction of hydroxyethylmethacrylate (HEMA). The molecular structure of MPTO was identified by FTIR and 1H-NMR, 13C-NMR, and GC-MS spectra. The synthesized MPTO oligomer was impregnated with polyurethane acrylate to make the various formulation of UV-cured coatings. The polyurethanes-MPTO oligomers were coated on wood and galvanized steel panels. The properties of UV-cured PU-MPTO were studied by differential scanning calorimeter (DSC), while their crystallinity by X-ray diffraction analysis (XRD). The thermo-gravimetric analysis (TGA) exhibited a high char yield of 18.4% at 800 °C. Moreover, coating films show prominent flame retardancy with UL-94 V-0 rating and maximum limiting index value (LOI) values of 34.8%, which are much higher than the common polyurethane coatings. The polyurethane coatings cured with MPTO exhibited excellent mechanical properties were estimated various tests such as adhesion, pencil hardness, solvent resistance, flexibility, and corrosion test. The coating performance revealed that MPTO improves the mechanical, thermal, and flame retardant properties because their unique structure contains melamine-phosphate moiety and long aliphatic chains of an acrylate ester. These high-performance melamine-based UV-curable coatings are promising for extensive applications.