Synthesis And Performance Research Of High Solid Polyurethane Coatings

Polyurethane coating has similar characteristics to acylamino group, such as intensity, wear resistance and oil resistance, also it has heat resistance and solvent resistance of polyester, water resistance and compliance of polyether, these outstanding characteristics make it be widely used. High solid polyurethane coating has other advantages besides the above mentioned, for example, high solid content, low pollution to environmental, high efficiency of construction, excellent decorativeness and protectiveness and so on, so it is more and more welcome.Taking MDI and diverse polyether as raw materials, by using of pre-polymer method, is synthesized curing agent. namely component A of polyurethane coating. Some influencing factors are discussed in detail, including reaction temperature, reaction time, mole ratio of (-NCO) and (-OH), moisture content, reactive diluents and inhibitive substance etc. By mensurating the pre-polymer's isocyanate value and viscosity, and Fourier transform infrared spectroscopy (FTIR) characterization of its structure, the optimal reaction conditions is determined: temperature at 80±2℃, reaction time is 2.5 hour,0.3% phosphoric acid is added in the pre-polymer, The pre-polymer synthesized is of low viscosity and high storage stability.Mixing the pre-polymer (component A) with component B composed of highly active polyether, chain-extender, catalyst, dispersant etc. Preparing high solid polyurethane coatings under high-speed stirring, selecting proper substrates to coated on, studying the coating's solid content, film coating's adhesion, hardness, water absorption rate, salt water resistance and ac impedance, to determine the coating's mechanical and physical property, infiltration resistance, corrosion resistance, and electrochemical protectiveness, and the result indicates that this coating is of over 80% solid content, hardness of film is 1 grade, adhesion of film is the best at 30μm thickness, the more thick of film the better adhesion of film. Though saline immersion experiment and A.C.impedanc experiment indecated that film has good permeability resistance, corrosion resistance, and electrochemical protectiveness.