| Because of the good tensibility and tensile-strength, excellent endurance of water, low temperature, grind, acid and alkali, polyurethane (PU) waterproof coating has been widely used in architecture, water conservancy and public service in America, Japan and other developed countries since 1980s.With the rapid development of the architecture and water conservancy and the constantly elevation of project quality in China, more and more advanced waterproof coating is needed. But because of the high price of PU waterproof coating, it has difficulties to use it widely. So tar PU waterproof coating is widely used in the past .It is washed out because it pollutes the environment. Now, bitumen PU waterproof coating is widely used, but it also has many problems such as too long solidified time and the impossibility of being brushed for more than one time. So its applied prospect has been doubted.Now petroleum resin is overstocked and very vile interiorly. It is harmless for environment and has an excellent ornamental performance and it can be compatible with prepolymer of PU. So petroleum resin PU waterproof coating has an excellent applied prospect.Material engineering college of Zhengzhou university cooperated with Water conservancy institute of Henan Province since 2002.The prepolymer of PU is synthesized with polyether and toluol diisocyanate and NCO% is controlled .The factors which influence reactive velocity are discussed. Petroleum resin PU waterproof coating is synthesized with the prepolymer of PU which is group A and petroleum resin, extender, stuffing and other material which are group B. The factors influencing mechanical performance are discussed. The factors influencing waterproof performance are also discussed. The coating is attributed by IR, SEM, TG, DSC and its rheological behavior is also attributed. The result is shown as following.1. The degree of polymerization of the reaction between TDI and polyether willbe raised with the reactive time. Reactive velocity will be raised with the increase of reactive temperature in a certain reactive time. On the condition of the same functionality, the reactive velocity will be debased with increase of molecular weight of the polyether because the density of functionality will be debased with the increase of molecular weight. The reaction is a second-order one and it is decided by the density of — NCO and —OH. It is deviated from second-order reaction because of the side reaction. NCO/OH is adjusted to get proper NCO%. And NCO% is controlled at 3%-5% to get better elongation at break and tensile-strength. Contrasted with organic amine, organic metal catalyzer has better effect on the reaction.2. Petroleum resin PU waterproof coating is synthesized for the first time with the prepolymer of PU and petroleum resin, extender, stuffing and other material. Petroleum resin waterproof coating has a good mechanical performance. Elongation at break is 660% and tensile-strength is 2.21 Mpa. Its performance can ultimately accord with the points of product I of The Country Criteria of PU Waterproof Coating (GB/T19250-2003).3. Molecular weight of the polyether, extender and NCO% have effect on the waterproof performance. Proper polyether, extender and NCO% are selected. The conservation rate of elongation at break is 117% and conservation rate of tensile-strength is 91%. So petroleum resin PU waterproof coating has a better waterproof performance.4. According to IR and SEM, the structure of petroleum resin PU waterproof coating is studied. The result is shown that petroleum resin is used as a nonreactive component. Petroleum resin can be compatible with prepolymer of PU and the performance of the coating can be elevated more.5. According to TG and DSC, the thermal properties of petroleum resin PU waterproof coating is studied. The result is shown that petroleum resin debases Tgof the coating. The thermal degradation process follows 2 steps. The starting equilibrium thermal degradation temperature is 231.04°C. And the mechanism of the thermal degradation accords with the hypothesis of Freeman-Carroll. The increase of the content of petroleum resin corresponds to the decrease of the thermal stability.6. The coating is pseudoplastic fluid and its apparent viscosity will be debased with the increase of shear rate. The non-newtonian exponent is no more than 1 and will be debased with the increase of temperature. Its flow activation energy is... |
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