Study On The Synthesis & Modification Of Waterborne Polyurethane And Its Application In Flame Retarded Coating

Some chemical reaction conditions on the physical and chemical properties of waterborae polyurethane were discussed, and the resulted waterborne polyurethane (WPU) was also modified chemically by epoxy and acrylic acid resins. The chemical and mechanical properties of waterborne polyurethane were characterized by infrared spectroscopy and other test methods.Results showed that the appropriate reaction temperature is 70℃, and the suitable molar ratio of -NCO to -OH is 2.4~3.5 when tolylene diisocyanate (TDI) reacted with polyoxypropylene glycol (PPG). While isophorone diisocyanate (IPDI) reacted with PPG, the appropriate temperature is 79~80℃, and the suitable molar ratio of -NCO to -OH is 2.6~4. WPU with excellent mechanical and water-resistant properties can be obtained by crosslinking when diethylene triamine substituted for ethylenediamine as chain extender. During the reactions between TDI and PPG, the solvent effectiveness can be overcome greatly when a suitable amount of dibutyl tin laurate (DBTDL) and triethylamine compound catalysts were added to the reactants. Furthermore, the environment has little influence on the reaction systems, and the reaction results obtained preserve better reappearance.The film of aromatic WPU preserves better mechanical properties than that of the film of aliphatic WPU. The film of WPU modified by epoxy resin preserves better mechanical and water-resistant properties, but worse latex stability. The film of WPU modified by acrylic acid has the best water-resistant property, but a flaw of crisp. The particle size of aromatic WPU latex is bigger, and the size distribution is wider than those of aliphatic WPU latex, especially in the high solid percentage of WPU latex.As for WPU flame retardant coatings, the inorganic flame retardant systems can't achieve the demand for excellent flame retardant, ornamental and water-resistant properties. The chemical intumescent flame retardant (CIFR) systems show littleimprovement on the ornamental and water-resistant property, but its flame retardant property is excellent. The physical intumescent flame retardant (PIFR) systems have worse ornamental property, but its water-resistant property is excellent.