Application Of Organosilicon Compound In Polyurethane Sealant

One-component polyurethane(PU) sealant is widely used as adhesives and elastic sealing material, because of its excellent properties such as good mechanical properties, excellent flexibility, high abrasive resistance and and chemical resistance.In this paper organosilicon compound were used into one-component PU sealant to modify its bonding properties, low temperature durability and thermal stability etc. It mainly includes two aspects, silicone modified PU sealant by polysiloxane(DHPDMS) and primer for PU sealant by silane coupling agents The main content and the results are as follows:In chapter2, The isocyanate-based siloxane primer for one-component PU sealant was prepared base on silane coupling agent and isocyanate compounds in order to improve the bonding property. Taking glass and concrete respectively as the substrate material, the optimal process conditions were determined first, and then the effect of isocyanate-based siloxane primer on bonding properties of sealant is studied. The results show that the isocyanate-based siloxane primer could significantly enhance bonding properties of PU sealant adhered on glass or concrete substrate. When the solid content of isocyanate-based siloxane primer is15%and the intervals is15min,galss substrate for PU sealant has bettter bonding performance,the resultant peel strength reached to9.5N/mm, The joint failure was cohesive failure by external force,only decreased32%from the original after7days water soakage, and still kept4.1N/mm after4times of temperature cycle.In chapter3, one-component polysiloxane/polyether Polyurethane sealant prepolymer were synthesized by the addition reaction of dihydroxybutyl-terminated polydimethylsiloxane (DHPDMS) with isocyanate-terminated polyether PU prepolymer,which was prepared by polymerization of2,4-tolylene diisocyanate (TDI) and polyether(PPG). The effects of content of HDPDMS on the properties of modified PU sealant prepolymer were studied and discussed.The results shows that with increasing the content of DHPDMS, the degree of micro-phase separation increases, the tensile strength decreased, aslo the low temperature durability and thermal stability is obviously improved.When the content of DHPDMS is15%, the modified PU sealant prepolymer has a proper degree of micro-phase separation and the mechanical properties is better,the glass transition temperature (Tg) decreased from-58.6℃ to-79.8℃,with a decrease about21.2℃compared to polyether PU prepolymer.Meanwhile, the initial decomposition temperature is higher than polyether PU prepolymer and hot weightlessness is only85%when temperature is417℃...