Study On Preparation And Capability Of Two-component Polyurethane Sealant

In this paper, a renewable castor oil (CO) and PAPI were used as material to synthesized of two-components polyurethane solventless sealant. The structure of polyurethane sealants were characterized through infrared spectroscopy (FTIR), and thermal stability of polyurethane sealant was studied by thermogravimetry (TG) analysis and differential scanning calorimetry (DSC).Before reaction, castor oil was dehydrated. Reaction time of prepolymer A was ascertained through content of -OH in polyester polyol by acetylating method.Reaction time of prepolymer B was ascertained through content of -NCO by di-n-Butylamine-Acetone method. And then, A and B were mixed to make out two-components polyurethane solventless sealant with suitable proportion. The effects of temperature, isocyanate index, catalysts and salt spray were discussed systemically, and the most suitable reaction condition of the every reaction was acquired. In salt spray test, an artificial salt spray environment was made to examine anticorrosion performance of polyurethane sealants. Different salt spray time at same reaction condition and different reaction condition in same time of reaction were compared by groups of tests. The mechanical properties change of the tensile shear strength and shear impact strength were determined.The results show that polyurethane sealant has excellent properties when reaction time of prepolymer A between 2.5 h and 3 h, reaction time of prepolymer B between 0.5h and 1h, reaction temperature 40℃, isocyanate index 1.6, catalyst 0.005~0.01%. At the situation, it is the shortest surface try time at 75 min, and the shortest setting time at 2 days, the strongest of strength properties in shear about 2.63 MPa and the strongest of shear impact about 15.9 MPa. It was different mechanical properties of polyurethane sealant different salt spray time. Change of mechanical properties was not very observable after 10 hours spray time. Ability of resistance salt spray corrosion was better when isocyanate index 1.6 and catalysts 0.01~0.02%.