UV-Curing of Novel Tri-functional Melamine-phosphate Oligomer: An Effect of Coating With Polyurethane Acrylate Towards Mechanical, Thermal And Flame Retardant Properties

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.

Preparation and Characterisation of Polyurethane Acrylate-Based Titanium Dioxide Pigment for Blue Light-Curable Ink

Herein, a polyurethane acrylate-based TiO2 (PU-TiO2) was fabricated using a two-step method. First, a polyurethane prepolymer was prepared. Second, PU-TiO2 was prepared using amino-modified TiO2 (A-TiO2). The best synthesis process of the polyurethane prepolymer was when the reaction temperature was 80 °C, the reaction time was 3 h and the R-value of the polyurethane acrylate was 2. Next, the influence of the A-TiO2 content on the structure and performance of PU-TiO2 was examined. The analysis of the rheological properties of the PU-TiO2 ink indicated that its viscosity gradually increased as the A-TiO2 content increased. The tensile performance of film improved because of the presence of A-TiO2. The photo-polymerisation and photo-rheological performance indicated that the PU-TiO2 structure changed from a hyperbranched structure with TiO2 as the core to a segmented structure, as the A-TiO2 content was 3%.